Editors Note: The history of nuclear testing is a very large subject. Testing went on for 48 years, and over a thousand tests were done by the US alone. If you add in all other countries known to possess nuclear weapons, the number of tests would more than double. It will be necessary to set some limits regarding what this section will attempt to cover. The early years, those in the 40's and 50's that led up to the hydrogen bomb and the early improvements in it will be covered in some detail. A brief description of each test shot will be provided with as much information as possible. Only U.S. tests during the 17 years of atmospheric testing will be covered in this section.

Statistics

The United States has conducted 1,054 tests of nuclear devices between July 16, 1945 (at the Trinity site in the New Mexican desert) and September 23, 1992 (at the Nevada Test Site). During the early years, before 1962, all of the tests were atmospheric, exposed to the atmosphere either on land or in the Pacific or Atlantic oceans, but overall the majority were underground tests, 839. The vast majority of tests were conducted at the Nevada Proving Grounds now known as the Nevada Test Site, 928, but a number were conducted at various locations in the Pacific, 108. Most of the Pacific tests were done at Eniwetok - 43, Bikini Atoll - 23, Christmas Island - 24, and Johnston Island - 12. A variety of means were used to deploy the devices for testing; airdrops, tunnels, balloons, shafts, barges, towers, as well as one on the surface of the ground and some rocket launched tests. Between the years of 1951 and 1992 there were multiple tests every year except for the test ban period of 1959 and 1960. The high point was 1962, when 98 tests were conducted. Prior to 1965 the tests were done in groups known as Series or Operations, which were named, i.e.: Crossroads, Ivy, and Castle. Within these groups individual tests were also named, i.e.: Able, Dog, and Nancy. The individual tests are referred to by the name of the Operation or Series then their specific name. As an example, Operation Ivy consisted of the Mike and King tests, which are known as Ivy Mike and Ivy King. Some Operations consisted of a dozen or more individual tests. The individual bombs or devices (Not all of the tests involved bombs, many were not usable as weapons, i.e. They couldn't be dropped from a plane or fired at an enemy. They were experimental devices put together to test subsystems or entire designs proposed for weapons use) being tested were also named, many were numerical designations indicating the style of bomb as well such as Mark 6 or Mark 14, abbreviated as Mk-6 or Mk-14. After 1965 test series were divided by fiscal year rather than operation. Each test was given a name and each years tests were grouped under an Operation name corresponding to a particular fiscal year. Tests were done for several different purposes, which were divided into categories: Weapons Related, Safety Experiments, Storage-Transportation, Plowshare, Weapons Effects and Vela Uniform (designed to improve ability to detect and locate underground tests). Data was collected on the tests and analyzed by one or more of the National Laboratories, Los Alamos, Lawrence Livermore, or Sandia. Originally the results of the tests were classified but now a substantial amount of the material has been declassified and released to the public.

In The Beginning…

...there was Trinity, the worlds first atomic bomb, tested successfully on July 16, 1945. The device being tested, nicknamed Gadget, was an implosion type with plutonium fuel and it had been hoisted to the top of a 100 foot tower. A great deal depended upon the results of this first bomb test, whether or not there would be an invasion of the home islands of Japan, whether or not the $20 billion spent on the Manhattan Project had been wasted, whether or not the bomb would ignite the atmosphere and destroy the world (Fermi was jokingly taking side bets). The Scientists at Los Alamos produced two bomb designs, one using uranium 235 and another using plutonium. Little Boy, the uranium bomb was a simple gun type weapon, which the scientists were confident, would work and which did not require testing. Gadget, the plutonium cored implosion bomb, was more complex. The design worked by compressing the plutonium into a critical mass, which could sustain a chain reaction. The compression of the plutonium ball was to be accomplished by surrounding it with lens-shaped charges of conventional high explosives, which had been precision cast for the purpose. They were designed to all explode at the same instant. The force was directed inward, thus crushing the plutonium core and increasing the density of the sphere. This would have to be tested, experimental verification of the projected results was important since a number of new design principles were involved. Plans were underway to test the device and from a list of eight sites in California, Texas, New Mexico and Colorado, Trinity Site was chosen as the test site. The area already was controlled by the government because it was part of the Alamogordo Bombing and Gunnery Range, which was established in 1942. The secluded Jornada del Muerto was perfect as it provided isolation for secrecy and safety, but was still close to Los Alamos.

In the fall of 1944 preparations got underway at the site. A military police unit arrived from Los Alamos at the site on Dec. 30, 1944. The unit set up security checkpoints around the area and had plans to use horses to ride patrol. It was determined however that the distances were too great and they resorted to jeeps and trucks for transportation and the horses were used for polo games with brooms and a soccer ball. Throughout early 1945 other personnel arrived at Trinity Site to help prepare for the test. An electric supply system was built, a fire department established, water hauled from the nearest town for drinking, gasoline and diesel was purchased from the Standard bulk plant located in Socorro. A post office box, number 632, was rented in Socorro so that mail service could be established. Base camp was located 10 miles southwest of ground zero. The George McDonald ranch house was located just two miles from ground zero. McDonald ranch was used for assembly, the master bedroom had been turned into a clean room for the assembly of the bomb core. Contractors built two towers, one for Trinity and one for the 100 Ton Test. In this test 108 tons of TNT were stacked on top of a 20 foot platform at the top of a tower 800 yards south of Zero. The purpose of this test was to calibrate the equipment for the Trinity test. It was the largest conventional explosion ever detonated. The tower at Zero was prefabricated and erected atop concrete footings set 20 feet deep and spaced 35 feet apart. A platform and shelter were placed at the top as well as an electric heavy duty winch. Construction of the 100 foot tower at ground zero was completed.

As the date for the test approached a number of last minute problems had to be addressed. By May 31 there was enough plutonium from Hanford to begin experimentation to verify the critical mass. Robert Cristy had designed the core as two solid hemispheres that were less than critical until they were compressed to at least twice their original density by high explosive surrounding them. The critical mass was confirmed in experiments June 24. Very shortly before the test a problem arose. The two pieces of plutonium for the core had been cast and plated with nickel to prevent corrosion and absorb alpha particles. Three days before the test the nickel plating began to bubble up due to plating solution trapped beneath it. The resulting bumps prevented the spheres from fitting together properly and had to be ground down and the surface smoothed with gold foil. The high explosive lenses that had been cast began arriving in June, produced by George Kistiakowsky's team a number contained small air bubbles and many were rejected for this reason or due to chipped corners. Only perfectly shaped lens castings were to be used and there were not enough of these as of July 9. Kistiakowsky finally resorted to drilling into the castings with a dental drill and filling the cavities with molten explosive slurry. He was able to rehabilitate enough castings to make more than two complete spheres, each consisting of 96 blocks. The material was a mottled brown color, somewhat waxy and in total weighed nearly 5,000 pounds for each device. On July 10 a weather front moved in bringing bad weather.

On July 12 the two hemispheres of plutonium were delivered to the McDonald ranch. At the house, Brig. Gen. Thomas Farrell, deputy to Maj. Gen. Leslie Groves, was asked to sign a receipt for the plutonium. Farrell later said, "I recall that I asked them if I was going to sign for it shouldn't I take it and handle it. So I took this heavy ball in my hand and I felt it growing warm, I got a certain sense of its hidden power. It wasn't a cold piece of metal, but it was really a piece of metal that seemed to be working inside. Then maybe for the first time I began to believe some of the fantastic tales the scientists had told about this nuclear power." At one minute past midnight on Friday, July 13, the explosives assembly left Los Alamos for Trinity Site. Later in the morning, assembly of the plutonium core began. Robert Bacher was the advisor; Marshall Holloway and Philip Morrison had overall responsibility. Louis Slotin, Boyce McDaniel and Cyril Smith were responsible for the mechanical assembly in the ranch house. Assembly of the test device began at 1300 hours. The team tried to use only tools and materials from a special kit. Several of these kits existed and some were already on their way to Tinian by different routes.

The idea was to test the procedures and tools at Trinity as well as the bomb itself. On July 14 the assembled core was driven to ground zero for final assembly at the base of the tower. Holloway was responsible for the mechanical assembly at the tower. The plutonium core was inserted into the device with some difficulty. On the first try it stuck. After letting the temperatures of the plutonium and casing equalize the core slid smoothly into place. The next morning the entire bomb weighing two tons was raised to the top of the 100-foot steel tower and placed in a small shelter. A crew then attached all the detonators and by 5 p.m. it was complete. Three observation points were established at 10,000 yards from ground zero. These were wooden shelters protected by concrete and earth. The south bunker served as the control center for the test. The automatic firing device was triggered from there as key men such as Dr. Robert Oppenheimer, head of Los Alamos, watched. Many scientists and support personnel, including Gen. Leslie Groves, head of the Manhattan Project, watched the explosion from base camp. Most visiting VIPs watched from Compania Hill, 20 miles northwest of ground zero.

The test was scheduled for 4 a.m. July 16, but rain and lightning early that morning caused it to be postponed. The device could not be exploded under rainy conditions because rain and winds would increase the danger from radioactive fallout and interfere with observation of the test. At 4:45 a.m. the crucial weather report came through announcing calm to light winds with broken clouds for the following two hours. At 5:10 the countdown started and at 5:29:45 the device exploded successfully. To most observers the brilliance of the light from the explosion--watched through dark glasses--overshadowed the shock wave and sound that arrived later. Those present were largely caught up in the sense of anticipation, excitement, fear of failure…a dozen conflicting emotions. It was not till after the fireball began to rise that many of them considered what this event meant. This was a revolution, a giant leap in destructive power. Its yield was the equivalent of 21 kilotons of TNT. The crater left where the tower had been was 2.9 meters deep and 335 meters across. Residents of Santa Fe and El Paso could see the flash. The shock broke windows 120 miles away and was felt by many at least 160 miles away. Brigadier General Thomas F. Farrell recalled:

In that brief instant in the remote New Mexico desert the tremendous effort of the brains and brawn of all these people came suddenly and startlingly to the fullest fruition. Dr. Oppenheimer, on whom has rested a very heavy burden, grew tenser as the last seconds ticked off. He scarcely breathed. He held on to a post to steady himself. For the last few seconds, he stared directly ahead and then when the announcer shouted "Now!" and there came a tremendous burst of light followed shortly thereafter by the deep growling roar of the explosion, his face relaxed into an expression of tremendous relief. Several of the observers standing back of the shelter to watch the lighting effects were knocked flat by the blast....All seemed to feel that they had been present at the birth of a new age -- The Age of Atomic Energy -- and felt their profound responsibility to help in guiding into the right channels the tremendous forces which had been unlocked for the first time in history. (Photo)

The world was now a different place than it had been, how different would be demonstrated at Hiroshima and Nagasaki. Little Boy, the bomb dropped at Hiroshima was a uranium fueled, gun type device with a yield of 15 kilotons. Fat Man, the bomb used at Nagasaki was a plutonium fueled, implosion type device which yielded 21 kilotons. [ A section on the Hiroshima and Nagasaki bombs and their human toll is coming in the near future. The Webmaster] The end of World War Two signaled the beginning of the age of nuclear weapons. Development efforts for new, improved bombs began just weeks after the first use of the weapon. Investigation of the effects of the weapons used on Japan and exploration of various designs for more efficient, more powerful devices would inevitably lead to the need to test the resulting weapons and the new design principles needed to produce them. On November 10, 1945 a subcommittee of the Joint Chiefs of Staff was formed to plan for the first postwar series of test explosions. In December President Truman issued a directive to hold joint Army and Navy testing "to determine the effect of atomic bombs on American warships." A plan was conceived and Truman approved the plan January 10, 1946.

The Marshall Islands

The Marshall's consist of 29 low-lying atolls and 5 islands covering 357,000 square miles in the Pacific Ocean North of the equator and almost directly East from Guam. Divided into two chains, the Eastern or Ratak group includes the atolls Mili, Majuro, Maloelap, Wotje, and Likiep. The Western or Ralik group includes the atolls Jaluit, Kwajalein, Wotho, Bikini, and Eniwetok. The islands rise only a few feet above sea level and total only slightly over 70 square miles. The current population is 65,507 (July 1999 est.) Sighted by Spanish explorer Alvaro Saavedra in 1529 but Europeans did not land there until the eighteenth century. In 1788 British named the islands after one of their exploring naval captains. After having been independent since the original Micronesian inhabitants arrived from other islands, the Marshall Islands were claimed as a protectorate of Germany in 1886 with the permission of the Chiefs of the Marshallese and the British. An attempt was made by the Germans to colonize the islands beginning in 1885, but this was unsuccessful. The islands main product was copra produced from the abundant coconut crop from the fertile Southern islands and atolls. In 1914, during World War I, the Japanese seized the Marshalls. In 1920 the Japanese received a League of Nations mandate and took over administration of the island chain.

During World War II Japan occupied the Marshall's and had their primary installation on Kwajalein Atoll, with small outposts on a number of the outlying atolls. As the war turned against Japan the United States wrested the Marshalls from the Japanese in 1944. From that point through the remainder of the war the islands were occupied by the United States. The U.S. established the Pacific Nuclear Proving Grounds in the Marshalls in February of 1946 beginning with Bikini Atoll and then including Eniwetok in December of 1947. In 1947 the United Nations designated the United States as administrator of the Trust Territory of the Pacific Islands, which included the Marshalls, the Marianas and Carolines. Under the trust agreement the U.S. was permitted to close the Marshalls to ensure the security of the Nuclear Proving Grounds. Article 5 entitles the United States to establish naval, military, and air bases and to erect fortifications in the territory. Article 6 obliges the United States to "promote the economic advancement and self-sufficiency of the inhabitants ... regulate the use of natural resources; encourage the development of fisheries, agriculture, and industries; protect the inhabitants against the loss of their lands and resources ... [and] protect the health of the inhabitants ... ". Article 13 recognizes the authority of the administrator to close areas for security reasons. A number of test series were conducted at the Pacific Proving Grounds. In addition to Crossroads in 1946 and Sandstone in 1948 there were Greenhouse in 1951, Ivy in 1952, Castle in 1954, Wigwam in 1955, Redwing in 1956, and Hardtack I in 1958. The signing of the Limited Test Ban in August of 1963 meant the end of atmospheric testing and therefore the end of testing in the Marshall Islands.

The U.S. continued to administer the Marshall Islands under the Trust Territory until 1986 when Congress approved the Compact of Free Association, approved in a plebiscite by Marshall Islands voters in 1983. The Compact includes a Section 177 trust fund of $150 million that is to provide $270 million in compensation payments over the 15 year life of the Compact (Bikini $75 million; Eniwetok $48; Rongelap $37 million; Utrik $22 million; Nuclear Claims Tribunal $45 million; $2 million annually for medical care for the "four atolls", and $53 million for a nationwide radiological survey). The Compact includes an espousal provision, prohibiting Marshall Islanders from seeking future legal redress in U.S. courts and dismissing all current court cases in exchange for a $150 million compensation trust fund. On October 21 of 1986 the Compact took effect. The Marshall Islands are now the Republic of the Marshall Islands with a constitutional government in free association with the U.S. The Marshallese celebrate the Proclamation of the Republic of the Marshall Islands, May 1 (1979) and October 21 (1986) their date of independence from the US-administered UN trusteeship. The islands produce coconuts, cacao, taro, breadfruit, fruits; pigs, and chickens and export fish, coconut oil, fish, and trochus shells. President Imata Kabua (since January 14 1997) faces reelection November 1999 governs along with a unicameral Parliament or Nitijela (33 seats; members elected by popular vote to serve four-year terms). According to the CIA World Fact book:

US Government assistance is the mainstay of this tiny island economy. Agricultural production is concentrated on small farms, and the most important commercial crops are coconuts, tomatoes, melons, and breadfruit. Small-scale industry is limited to handicrafts, fish processing, and copra. The tourist industry, now a small source of foreign exchange employing less than 10% of the labor force, remains the best hope for future added income. The islands have few natural resources, and imports far exceed exports. Under the terms of the Compact of Free Association, the US provides roughly $65 million in annual aid, equal to about 70% of GDP. Negotiations will get underway in 1999 for an extended agreement. Government downsizing, drought, a drop in construction, and the decline in tourism and foreign investment due to the Asian financial difficulties have caused GDP to fall in 1996-98.

During the period from June 30, 1946, to August 18, 1958, the United States conducted 67 nuclear tests in the Marshall Islands, all of which were considered atmospheric. The most powerful of those tests was the "Bravo" shot, a 15 megaton device detonated on March 1, 1954, at Bikini atoll. That test alone was equivalent to 1,000 Hiroshima bombs. While the Bravo test is well known, it should be acknowledged that 17 other tests in the Marshall Islands were in the megaton range and the total yield of the 67 tests was 108 megatons, the equivalent of more than 7,000 Hiroshima bombs. For the sake of comparison, it may be noted that from 1945 to 1988, the U.S. conducted a total of 930 known nuclear tests with a combined yield estimated to be 174 megatons. Approximately 137 megatons of that total was detonated in the atmosphere. In other words, while the number of tests conducted in the Marshall Islands represents only about 14% of all U.S. tests, the yield of the tests in the Marshalls comprised nearly 80% of the atmospheric total detonated by the U.S.

Under Article IV of the Section 177 Agreement, The Governments of the United States and the Marshall Islands agreed to the establishment of a Claims Tribunal which would have jurisdiction "to render final determinations of all claims past, present and future, of the Government, citizens and nationals of the Marshall Islands which are based on, arise out of, or are in any way related to the Nuclear Testing Program, and disputes arising from distributions made under Article II and III of this agreement." The Nuclear Claims Tribunal to address personal injury and property claims resulting from the nuclear testing in the Marshall Islands and provided for in the Compact of Free Association was begun in 1988. Jurisdiction for all claims was invested in the Tribunal. It was authorized to issue regulations specifying which diseases were assumed to be caused by radiation exposure but was urged by the scientist consulted not to do so. They recommended that the Tribunal follow the precedent established by various courts in radiation-damage lawsuits by requiring proof of causation or, at a minimum, a demonstrated probability that a compensible medical condition was the result of an individual's exposure to radiation from the testing program. When the Tribunal approached the U.S. government for exposure data they found that none was forthcoming for any population other than Rongelap or Utrik. Without reliable information about the exposure level of individuals who had been living on other atolls, there could be no proof or showing of a probability that radiation had caused the medical conditions suffered by those individuals. This made it impossible to settle any of the claims until an alternate method was discovered of establishing causation.

In late 1990, the Tribunal became aware of U.S. legislation known as the "Downwinders' Act". Congress determined that fallout emitted from the atmospheric nuclear tests conducted at the Nevada Test Site had exposed American civilians "to radiation that is presumed to have generated an excess of cancers among those individuals" and based on that finding, a program had been established to provide compensation for specified diseases to U.S. civilians who were physically present in any "affected area" during the periods of atmospheric testing in Nevada (between January 1951 and October 1958 or during July 1962). The Tribunals enabling legislation had authorized this presumptive approach. It addressed the need for a straightforward means of determining which injuries could be attributed to radiation exposure during the testing period while recognizing the impossibility of an individual proving that their injuries or disease were due to exposures to ionizing radiation. A list of 25 conditions was drawn up which the Tribunal determined were compensible and the area defined as affected was determined to be the entire area of the Marshall Islands.

In 1991 the first awards were granted by the Nuclear Claims Tribunal for injuries sustained during testing but due to concerns regarding the adequacy of the $45 million allocated for the fund only 25% of the total award is issued to claimants. December 1995 it was announced that the Nuclear Claims Tribunal had awarded $43.2 million, to 1,196 claimants for 1,311 illnesses. The fund was nearly depleted and the Tribunal estimated in August of 1996 that $100 million in personal injury claims will have been filed by the end of the Compact period in 2001. This does not include land claims which are also pending before the Tribunal. As of the end of 1997, net awards of compensation totaling $63 million had been made by the Tribunal to or on behalf of 1,549 individuals who suffered from one or more of the 34 conditions then on the list. Two thirds of the awards have been for thyroid disorders. The fund to pay the claims is limited to $45 million by the terms of the Compact, however there is a clause outlined in the 177 Agreement. Article IX of the Agreement is entitled "Changed Circumstances." It provides that:

If loss or damage to property and person of the citizens of the Marshall Islands, resulting from the Nuclear Testing Program, arises or is discovered after the effective date of this Agreement, and such injuries were not and could not reasonably have been identified as of the effective date of this Agreement, and if such injuries render the provisions of this Agreement manifestly inadequate, the Government of the Marshall Islands may request that the Government of the United States provide for such injuries by submitting such a request to the Congress of the United States for its consideration. It is understood that this Article does not commit the Congress of the United States to authorize and appropriate funds.

The Changed Circumstances cited are the increased knowledge of the biological effects of radiation since the original agreement and changes in the maximum exposure level limits. In Article VIII of the Section 177 Agreement, the United States concluded, the Northern Marshall Islands Radiological Survey and related environmental studies conducted by the Government of the United States represent the best effort of that Government accurately to evaluate and describe the radiological conditions in the Marshall Islands. During 1995, a January 1955 report from the U.S. Atomic Energy Commission (AEC) entitled Radioactive Debris From Operation Castle, Islands of the Mid-Pacific was made available to the Republic of the Marshall Islands for the first time. That report, which had been classified for 40 years, includes tables listing radiation fallout doses as measured for 27 Marshall Islands atolls for each of the six tests conducted in the 1954 series. The cumulative doses contained in that report were apparently not of great concern at the time, except for Rongelap, Ailingnae and Utrik.

In 1957, the U.S. National Bureau of Standards published an addendum to its report #59 for the National Council on Radiation Protection (NCRP) in which a new public limit of 0.5 rem (500 mrem) per year was established for maximum permissible exposure. Two years later, in 1959, the International Commission on Radiological Protection set a maximum general public limit of 0.17 rem (170 mrem) per year (ICRP Publication 2). [It should be noted that in 1990 the ICRP reduced the general public limit to 1 mSv (100 mrem) per year (ICRP Publication 60).] The cumulative doses contained in the 1955 AEC report for the Castle series are external only and do not combine internal doses, as current radiation protection standards now require. Also, for various reasons discussed in the report, the external values given are, in general, underestimation's. It should also be noted that the monitoring was conducted over only a 12-week period, not an entire year. It is reasonable to assume that unmeasured radioactive debris continued to fallout, in decreasing amounts, during the weeks and months following the conclusion of the series. Nevertheless, the exposure levels in that report show that 10 of the 22 populated atolls listed exceeded the NCRP 1957 maximum limit of 500 mrem over the period of an entire year for the general public and an additional 10 populated atolls exceeded the ICRP 1959 general public limit of 170 mrem for a whole year.

Because such information was not available to those negotiating the settlement on behalf of the Marshall Islands, the U.S. assertion that the 1978 survey represented its "best effort" to describe conditions in the Marshall Islands must be disregarded. In fact, the U.S. has still not put forth its best effort to describe such conditions since fallout measurements from the last two series of tests in the Marshall Islands still remain classified nearly 40 years after the final test, despite numerous requests made by the RMI government. Those two series - - - Operation Redwing in 1956, comprising 17 tests totaling 20.8 megatons, and Operation Hardtack I in 1958, comprising 33 tests totaling 28 megatons - - - had a combined yield greater than the Operation Castle series in 1954. The fact that the exposure levels sustained by people living on nearly every atoll in the Marshall Islands in 1954 exceeded U.S. and international maximum permissible levels established shortly thereafter clearly constitutes another area of Changed Circumstances. And it can be expected that those circumstances will change again when the U.S. finally makes available exposure level data from the 1956 and 1958 series. A renegotiation of the nuclear claims settlement based on the Changed Circumstances provision contained in Article IX of the Section 177 Agreement is clearly warranted. Without an extensive and impartial review of the currently known damages caused by the nuclear testing program and a substantial increase in the funding for payment of awards, it cannot truly be said that the Agreement constitutes the full settlement of all claims, past, present and future . . . related to the Nuclear Testing Program (Article X of the Section 177 Agreement). The total money and non-monetary compensation paid by the United States to Marshallese Islanders since 1956 to redress damages from nuclear testing over $759,000,000.

Bikini Atoll

Bikini, a coral atoll in the Marshall Islands was chosen as the location for the first test series due to its location away from regular air and sea routes, accessible ports, and land for test installations. It comprises a total of 2 square miles consisting of 36 islets on a reef 25 mi. long. Bikini had held a small Japanese outpost during the war but had long been somewhat isolated. It had been inhabited for nearly 2000 years. In February of 1946 the U.S. Military Governor of the Marshall Islands, Commodore Ben Wyatt, approached the atolls residents and asked if they would be willing to leave temporarily. They were told that their land was needed for the "good of mankind and to end all world wars." The 167 people of Bikini and King Juda agreed to do so. Residents of the Atoll were packed up and moved to a nearby island, Rongerik Atoll, some 125 miles from Bikini. Rongerik was uninhabited due to lack of water, small size, poor food supply, and a native belief that evil spirits roamed there. It was one sixth the size of Bikini. Within months the Bikinians were starving and pleading to go back home.

In March of 1948, on the verge of starvation, the Bikinians were taken off Rongerik Atoll and moved to Kwajalein, where they stayed for six months until another place was selected for their relocation. The 184 Bikinians moved to Kili, an uninhabited island in the Southern Marshalls in November of 1948. They remain there today. Numerous difficulties have confronted them on Kili including typhoons, forest fires, hunger, isolation and loss of their traditional diet and culture. The hardships on Kili prompted consideration of yet another relocation in April of 1952 and a number of alternatives were studied, including moving them back to Bikini. On April 2, 1953 Bikini was officially added to the Pacific Proving Grounds and the resettlement idea was definitely dropped. In the end, several additional uninhabited southern atolls were given to the Bikinians to attempt to provide them with sufficient resources to live adequately independently. In November of 1956 Bikini Islanders living on Kili are given $25,000 cash and a $300,000 trust fund (yielding about $15 per person annually).

The original "temporary" removal lasted until the 1970s. A clean up plan was developed and implemented to remove radioactive debris from Bikini and work was completed in 1972. This work included the construction of homes and planting of coconut palms and other food plants. Some remaining radioactivity was discovered in 1972 and questions were raised regarding the safety of the atoll for permanent inhabitants. The majority of the Bikinians on Kili voted to delay returning due to the new information, however they did not preclude individuals from doing so if they so desired. In 1973 three extended families of Bikinians moved back and began living in the newly built housing development. Regular radiological surveys were conducted to monitor the remaining radiation levels. In 1975 elevated levels of radiation were detected and in October the residents filed suit against the U.S. to force a complete survey. This was agreed to by the U.S., but not begun for three years. Residents remained on the atoll during this period. Finally in September of 1978 the people were evacuated from Bikini due to alarmingly high levels of Cesium¹³⁷ detected in the bodies of the 138 Bikinians. In September of 1978 The U.S. government funds a $6 million trust for the Bikini people. A lawsuit was filed by the people of Bikini against the U.S. for $450 million in compensation. The Bikinians filed a class action law suit against the U.S. government in U.S. courts seeking $450 million in compensation in 1981. In response, the U.S. government funded a second trust fund with $20 million in 1982 and latter added an additional $90 million.

Disagreement over the best method of decontaminating Bikini has been ongoing since the 1980s. The leading council of Bikini has insisted that due to the failure of the first attempt at resettlement, they wanted the entire island of Bikini excavated and the soil removed to a depth of about 15 inches. The scientific groups involved with the Bikini project stressed that while the excavation method would rid the island of the cesium-137, the removal of the topsoil would severely damage the environment, turning it into a virtual wasteland of wind-swept sand. Instead, they favor spreading potassium fertilizer over the entire island. This method blocks the uptake of cesium by plants and prevents its concentration in foodstuffs harvested from the crops grown on the island. Development of the infrastructure to support the cleanup and resettlement programs on Bikini Atoll started early in calendar year 1991. The program was concentrated at Eneu Island, which had been declared safe for habitation, and is the main support base for the cleanup activities. The first stage of clean up began in FY 1998 and included scraping of 300 acres on the lagoon side of Bikini, which will become the housing development. The crop producing areas will be treated with potassium.

Eniwetok Atoll

In July of 1947 the Marshall Islands and the rest of Micronesia became a United Nations strategic Trust Territory administered by the United States. In December 1947, Eniwetok Atoll was chosen for the second series of nuclear tests because it is larger than Bikini, with more land to build test facilities and emplace equipment. The AEC announced the selection of Eniwetok Atoll as a site for proving grounds because it "has the fewest inhabitants to care for and is isolated." The U.S. government will transfer the Eniwetok inhabitants to sites they will select and will reimburse them for the lands utilized. The AEC explains that the establishment of these proving grounds is necessary to provide a suitable area to verify by experimentation "indicated results" of laboratory studies. Bikini is unsuitable for such testing because it lacks sufficient land surface. Eniwetok is 50 mi. in circumference and comprises about 40 islets surrounding a large lagoon. The 145 residents of Eniwetok were removed to another atoll, Ujelang. Operation Sandstone, the first test series at Eniwetok, was scheduled to begin in April. AEC Chairman David E. Lilienthal informed President Truman that to meet U.S. Obligations under the Trusteeship Agreement, the U.S. government will accord "normal constitutional rights of citizens to the Eniwetokese but will treat them as U.S. wards; will keep displacement to the minimum required for their safety; will resettle the Eniwetokese according to agreements reached with them; and will provide adequately for their well-being in their new locations." On April 28, 1948 the AEC went on record as desiring that Eniwetok Atoll be retained as a permanent proving ground for nuclear weapons after the completion of Operation Sandstone. Necessary steps are taken over the next three years to finalize this arrangement.

Authorization was given in September of 1948 for payment of $515,360 to the Eniwetokese for the land area of which they were historic owners. The AEC refused to make payments without legal proof of ownership and had made none by August of 1951. In November of 1956 U.S. officials give the Eniwetok Islanders living on Ujelang $25,000 cash and a $150,000 trust fund (earning 3 1/3 percent annually) as compensation. On October 15, 1977 Public Law 95-134 authorized $12.4 million for rehabilitation and resettlement of Eniwetok Atoll. The nuclear cleanup at Eniwetok Atoll began in May. About 700 U.S. Army personnel carried out the cleanup's first phase, which included scraping and collecting 100,000 cubic yards of radioactive soil and debris, and 125,000 cubic yards of uncontaminated debris and removing it to a bomb crater on Runit Island. The cleanup efforts continued for the next three years. Then, the U.S. Defense Nuclear Agency announced in March 1980 that the Eniwetok nuclear cleanup was completed. The estimated cost of the cleanup and rehabilitation was $218 million. Eniwetok Islanders began returning to the southern islands in the atoll at that time.

Rongelap Atoll

The people living on Rongelap were not permanently displaced during the testing like those on Eniwetok and Bikini, but they were exposed to large amounts of fallout as a result of the Castle Bravo test in 1954. There is reason to believe that those in charge of performing the test knew, or should have known that the Atoll would be subject to fallout and did nothing. According to documents now available in its preliminary radiological safety plan for the Castle series the joint task force did not expect to evacuate native populations before the Castle Series. The rationale for not conducting such evacuations is based on February 1953 discussions between cognizant headquarters sections, radiological documentation from Ivy, "apparent unrealism in the assumption of health hazards of a magnitude conjectured for Ivy" a policy of financial austerity for FY 1954, and the unavailability of task force equipment for evacuations. The plan states, However, consideration of populated islands will be one of the major factors influencing the decision to shoot. Commenting on the proposals, H. G. Hopwood, chief of staff for the CINCPACFLT, advises the CINCPACFLT that the upwind populated areas present least concern since they are situated in a potentially safe region but that the cloud tracking within the danger area will not provide information useful to CINCPACFLT in the discharge of his responsibilities for the safety of other units and populated islands of the Pacific. . . . In the remote circumstance that extreme post shot conditions develop a necessity for the temporary evacuation of any populated island in the Marshalls, units of JTF-7 would be required to accomplish this emergency measure upon the request of CINCPACFLT.

On February 28, 1954 at 6 p.m. weather reports indicated that atmospheric conditions were getting less favorable. At midnight, just seven hours from the shot, the weather report reports there were less favorable winds at 10,000 to 25,000-foot levels. Winds at 20,000 feet "were headed for Rongelap to the east." On March 1 Bikini's weather outlook downgraded to "unfavorable" and Joint Task Force 7 directed several ships to move 20 miles to the south to remove them from the expected fallout zone. Despite weather reports showing that winds were blowing in the direction of inhabited islands, the March 1 Bravo hydrogen bomb test was detonated at Bikini. Within hours a gritty, white ash was enveloping islanders on Rongelap and Ailingnae Atolls. A few hours later, American weathermen were exposed to the snowstorm of fallout on Rongerik, and still later the people of Utrik and other islands experienced the fallout "mist".

Those exposed experienced nausea, vomiting and itching skin and eyes. Estimates differ on the amount of radiation exposure received by the Marshall Islanders. A military report made shortly after the detonation suggests Rongelapese exposures of "150 R. whole body gamma." Another military memorandum reports that 64 Rongelapese may have received up to 130 roentgens over 51 hours; 17 additional Rongelapese on Ailingnae, 80 roentgens in 58 hours; 154 Utrik residents, 17 roentgens in 78 hours; and 401 Ailuk inhabitants, not evacuated, less than 20 roentgens total doses for their lifetimes. An Armed Forces Institute of Pathology study estimates point source doses at "260 R." for the Rongelapese and "20 R." for the Utrik group. Later studies by the AEC/DBM estimate that some Rongelapese may have received a whole-body gamma dose of 175 roentgens; that 20 percent incurred deep lesions; 70 percent superficial lesions; and 10 percent, no lesions; and that 55 percent lost some hair, which regrew later. According to later estimates, the thyroid glands of young Marshallese children absorbed approximately eleven micro curies of iodine (131) and from 700 to 1400 rads. On March 2, 1954, after the task force radsafe officer measures 0.200 R/hr at 500 feet in a morning flyover at Rongerik, the radsafe officer evacuates 28 U.S. weather personnel from that atoll. An afternoon flight over the populated Marshalls extrapolates 1.350 R/hr at ground level at Rongelap; 0.400 R/hr at Ailingnae, 0.001 R/hr at Wotho, 0.240 R/hr at Utrik, and 0.076 R/hr at Ailuk. The flight over the unpopulated atolls calculates ground contamination as 0.600 R/hr at Bikar Island and Taongi Island at 0.014 R/hr. Task force officials then decide to evacuate Rongelap, Ailingnae, and Utrik Islands. They sent the destroyer USS Philip 43 nautical miles southwest of Eneu Island, to evacuate Rongelap and Ailingnae the following morning and the USS Renshaw, 13 nautical miles north of Eneu Island, to evacuate Utrik on March 4, 1954.

Meanwhile, radsafe monitors flown to Rongelap measured 1.400 R/hr in the living quarters of Rongelap island. Rongelap islanders were finally evacuated 48 hours later, and Utrik was evacuated 72 hours after Bravo. Both groups are taken to Kwajalein for observation. Skin burns on the heavily exposed people began to develop, and later their hair fell out. The U.S. Atomic Energy Commission issued a statement to the press calling Bravo a routine atomic test, and stating that some Americans and Marshallese were unexpectedly exposed to some radioactivity. There were no burns. All were reported well. On March 7 Project 4.1, Study of Response of Human Beings Exposed to Significant Beta and Gamma Radiation due to Fallout from High Yield Weapons, established a secret medical group to monitor and evaluate the Rongelap and Utrik people. In April a Project 4.1 memo recommended that the exposed Rongelap people should have no exposure for (the) rest of (their) natural lives.

On April 29 a Department of Defense report states that the only other populated atoll which received fallout of any consequence at all was Ailuk...It was calculated that a dose...would reach approximately 20 roentgens. Balancing the effort required to move the 400 inhabitants against the fact that such a dose would not be a medical problem it was decided not to evacuate the atoll. In May Utrik Islanders were allowed to return home because, according to U.S. officials, Their island was only slightly contaminated and considered safe for habitation. In July of 1957 Rongelap was declared safe for rehabilitationin spite of slight lingering radiation. The Rongelap people, who had been living temporarily in Ejit Island, Majuro, returned to Rongelap. In a Brookhaven National Laboratory report scientists state about Rongelap:

Even though the radioactive contamination of Rongelap Island is considered perfectly safe for human habitation, the levels of activity are higher than those found in other inhabited locations in the world. The habitation of these people on the island will afford most valuable ecological radiation data on human beings.

The first thyroid tumors began appearing in 1963 among the Rongelap people exposed to the Bravo test in 1954. Also, a higher than normal incidence of growth retardation among young Rongelap Islanders was noted by U.S. doctors. In January of 1966 the U.S. Congress approved an exgratia payment of $950,000 (about $11,000 per capita) to the exposed Rongelap people for injuries resulting from their exposure in 1954. In addition to the Marshallese the crew of the Lucky Dragon, a Japanese fishing boat, were exposed to fallout from the test. One crewman died and all suffered from radiation burns and sickness. The amount of money paid by the State Department to Japan following fallout from the 1954 "Bravo" test: $15,300,000

Operation Crossroads

Following the use of the nuclear bombs on Japan and the end of the war which they brought about, U.S. military planners saw the future of the military at a crossroads brought about by the new technology and the tremendous changes it brought about. This was the origin of the name for Operation Crossroads. That tests of the nuclear bomb would be conducted was a foregone conclusion and had been since the Chairman of the Senate's Special Committee on Atomic Energy had proposed the use of captured Japanese ships to show the effects of nuclear weapons in August of 1945. In September of 1945 the suggestion was placed before the Joint Chiefs by the Commanding General of the Army Air Forces. On December 10, 1945 President Truman announced that the U.S. would pursue development and testing of the new weapons under the jurisdiction of the Joint Chiefs of Staff. Crossroads was the first test series conducted in the Marshall Islands and the first since Trinity. Planned operations included detonation of two devices in two separate tests code named Able and Baker. The location to be used was Bikini Atoll and its lagoon, recently vacated by the Bikinians. As a safety measure, islanders from Eniwetok, Rongelap and Wotho atolls were also relocated from their homes for the duration of Operation Crossroads.

Over 42,000 U.S. military and civilian personnel were involved in Crossroads as well as 242 naval ships, 156 aircraft, 25,000 radiation recording devices, and 5,400 experimental rats, goats and pigs. Crossroads was a huge production. 90 vessels were set up as targets in the lagoon including the following, all of which were sunk: the Sakawa a captured Japanese heavy cruiser; the Destroyers USS Anderson and USS Lamson; the Attack Transports USS Carlisle and USS Gilliam; The Battleships USS Arkansas and Nagato a captured Japanese battleship; the Aircraft Carriers USS Saratoga; the Submarines USS Apogon and USS Pilotfish; and the Landing Craft LSM-60 (Surface Zero Ship for Baker). Crossroads target fleet consisted of "older U.S. capital ships, three captured ships, surplus U.S. cruisers, destroyers and submarines, and a large number of smaller auxiliary and amphibious vessels" provided by the Navy. Military equipment and ammunition was placed on the ships to determine the effects of the nuclear explosion on them and a number of amphibious craft were landed on Bikini Island to be exposed to the explosions. A support fleet of over 150 ships was used for living quarters, work space and laboratories for the 42,000 men (more than 37,000 of whom were Navy personnel) of Joint Task Force 1 (JTF 1).

The taskforce was organized on January 11, 1946. Needs of the scientific program of the test were considered in its composition. Joint Task Force 1 comprised Army, Navy and civilian scientific personnel and liaison was maintained with the War Department, Navy Department, Manhattan Engineer District, and other governmental agencies including the Joint Chiefs of Staff, the Presidents Evaluation Commission and several national laboratories including Los Alamos. The Task Force was divided into eight Task Groups, each of which performed some specific function. Task Group 1.1 the Technical Group, was responsible for placing instrumentation on the target ships and areas. Some of the ships in this Task Group were equipped with laboratories to aid in recording data. Task Group 1.2 the Target Ship Group, was responsible for the target ships, sailing them to the test location, and anchoring them in the lagoon according to the prepared plan. Task Group 1.3, the Transport Group provided transportation to personnel and equipment between the Support Fleet and the Target Fleet, and between the Support Fleet and Bikini Atoll. Task Group 1.4, the Army Ground Group, was responsible for providing and emplacing Army equipment for the Target Fleet and Bikini Atoll, determining damages from the tests, measuring radii of effectiveness for each detonation; and loading, unloading and transport of all Army equipment. Task Group 1.5, the Army Air Group, was responsible for dropping the Able device, photography of the tests, transportation of observers, and weather reconnaissance. Task Group 1.6, the Navy Air Group, provided drone planes for monitoring of the radioactive clouds produced by the weapons, aerial photography, and transportation by seaplane. Task Group 1.7, the Destroyer Surface Patrol Group, furnished radiation safety patrols, monitored arrivals and departures from the lagoon, and deployed two destroyers to act as approach markers for the bombing run. Task Group 1.8, the Service Group, provided base facilities, food service, hospital facilities, shore patrol, recreation, construction, shuttle service, general supplies and evacuation for Rongerik Atoll population if necessary.

Crossroads was to be well covered by the media, a contingent of 131 newspaper, radio and magazine reporters from the United States and a number of other countries were invited. Australia, France, Britain, the Soviet Union, Canada and the Republic of China were all represented. The correspondents were stationed aboard the USS Appalachian. Navy and U.S. Government personnel were also involved in recording every aspect of the tests on film. Eighteen tons of cinematography equipment and more than half of the worlds supply of motion picture film was on hand to record the movement of the Bikinians from their atoll, and the Able and Baker test detonations. Scenes of the instruments being prepared for the test, navy personnel playing beach volleyball and swimming in their off hours, the target fleet floating in the calm water of the lagoon were all filmed for audiences all over the world. This was going to be a very big deal, they had carefully planned to document the entire process. No aspect of the tests would go without observation, analysis and comment by the Military, and the public was to be included in much of it.

Vice Admiral Blandy discussed the tests aim and the role of the press in his press conference May 13, 1946. In this announcement the press was told that they would have access to the general arrangement of military equipment on Bikini Atoll, both before and after the test and from the water and the air. They were told that "the basic directives require that the test provide the essential data required by the Armed Forces. The tests are primarily planned, therefore, to determine and to measure with precision what happens at various distances when an atomic bomb is used against ships and other items of military equipment such as tanks, airplanes, radio sets, etc. Much information of value to pure science will also be obtained, and , where practicable, duplication or simulation is made of typical operating conditions." It was pointed out that the ships had been arrayed in the lagoon so that the maximum damage possible could be inflicted on the ships clustered at the aiming point by one bomb dropped from one airplane. The damage would progressively decrease with distance from this central cluster. Planners intended that the damage to the most distant target ships would be negligible. Typical conditions were to be approximated by loading the ships with combat supplies in differing amounts, some would be nearly fully stocked, and others would be nearly empty, as ships would be in the case of war.

Pains were taken to emphasize to the members of the press that "there is no thought of simulating an 'attack' by atom-bomb-loaded airplanes against a disposition of ships at sea or at anchor in a harbor" since the arrangement of ships had not been designed to approximate any sort of natural conditions, but rather "to insure doing major damage to a capital ship even if the bomb does not detonate exactly over the bulls eye, and, second, to provide a positively identifiable point of aim to the bombardier from a high bombing altitude. Other steps being taken to place the bomb over the aiming point with the extreme accuracy required in this test and not normally available or essential under war conditions include: Painting the battleship NEVADA at the center a bright red-orange, installing a radar beacon on the NEVADA, providing special destroyer station ships as navigation checks for the bomber's approach, and using precise radar methods for obtaining accurate wind data at all altitudes over the target." Some restrictions were placed on press coverage of the test, photographs were to be examined by the military for the following reasons:

Photographs produce exact and measurable records; analysis of large numbers of related photographs of bomb damage can evolve much precise information. While the press representatives who write for publication and broadcast by radio will be permitted to do so without censorship of their copy, the national security requires that all photographs be reviewed for security and that the information obtainable from photographs of damage be limited. Representative pictures showing damage will be released as soon as practicable after the tests, some by radio photo from Bikini. These pictures will be selected to provide the public with a true graphic record of the general effects of the test. Only such identification of ships and viewpoints in the photographs will be released as will not prejudice the security interests of our country.

Certain other information was to be withheld as well, including: the exact point of detonation of the bomb with respect to the point of aim of the target array, the altitude at which the bomb is detonated, the exact bearings and distances at which the ships are stationed with respect to each other, the special equipment and techniques used by the airplane involved in dropping this bomb, the exact pressures, temperatures and other data obtained at various distances from the point of burst, the degree of efficiency of the explosion, large numbers of detailed photographs showing bomb damage.

Being the first postwar test series, Operation Crossroads was bound to attract a great deal of attention. This operation consisted of two tests, Able and Baker. Each was a 21-23 kiloton device and the tests were designed to demonstrate the effects of nuclear weapons on Navy vessels. Crossroads was to be the first weapons effects test series, intended to determine the effect of nuclear weapons on objects as opposed to testing a new weapon design. Both the Able and Baker bombs were nearly identical to the Fat Man implosion type devices used at Nagasaki and Trinity, so no new technology was being demonstrated. Two means of delivery were to be used, Able was to be airdropped from a B-29 and Baker was to be detonated underwater suspended from the Landing Craft LSM-60. Able was scheduled first, with Baker to follow, on June 30, 1946 and July 24, 1946 respectively.

The support fleet and all personnel were withdrawn to a safe distance and the B-29 Dave's Dream made its pass and dropped the bomb which airburst over the target fleet in the lagoon. Possibly due to crew error or to the bombs tail fin having crumpled, the drop was off the aiming point by 1,870 feet left and 980 feet short. Five of the target vessels were sunk or damaged severely including USS Gilliam, USS Carlisle, USS Anderson, USS Lamson, and the Japanese heavy cruiser Sakawa. An observer located in a Navy plane 20 nautical miles from the explosion submitted the following observations of the Able detonation:

At twenty miles [it] gave us no sound or flash or shock wave….Then, suddenly we saw it-a huge column of clouds, dense, white, boiling up through the stratocumulus, looking much like any other thunderhead but climbing as no storm cloud ever could. The evil mushrooming head soon began to blossom out. It climbed rapidly to 30,000 or 40,000 feet, growing a tawny-pink from oxides or nitrogen, and seemed to be reaching out in an expanding umbrella overhead….For minutes the cloud stood solid and impressive, like some gigantic monument, over Bikini.

Radiation contamination of the target vessels decayed rapidly and was at 0.1R 24 hours after the test. Personnel were able to reboard the ships the next day to perform examinations of the results. Damage to the superstructures of the centrally located target ships was considerable, however, there was negligible damage to the hulls of the ships even those closest to ground zero. There were about 20 ships within half a mile, all of which were badly damaged, many being put out of action and five sunk. It required up to 12 days to repair all of those ships left afloat sufficiently so that they could have steamed under their own power to a major base for repair. Instruments were recovered which revealed information regarding the radiation levels experienced during the test. Analysis of these results brought the following conclusions as described in the Preliminary Report of the Joint Chiefs of Staff Evaluation Board submitted July 30, 1946:

Measurements of radiation intensity and a study of animals exposed in ships show that the initial flash of principal lethal radiation's, which are gamma-rays and neutrons, would have killed almost all personnel normally stationed aboard the ships centered around the air burst and many others at greater distances. Personnel protected by steel, water, or other dense materials would have been relatively safe in the outlying target vessels. The effects of radiation exposure would not have incapacitated all victims immediately, even some of the most severely affected might have remained at their stations several hours. Thus it is possible that initial efforts at damage control might have kept ships operating, but it is clear that vessels within a mile of an atomic bomb air burst would eventually become inoperative due to crew casualties.

The ships were inspected, some repairs and rearrangement of the target array done, and where necessary the ships were remoored in preparation for Baker. The preliminary conclusions of the Joint Chiefs of Staff Evaluation Board of the results of the detonation were outlined in their report:

As to detonation and blast effects, where the largest bomb of the past was effective within a radius of a few hundred feet, the atomic bomb's effectiveness can be measured in thousands of feet. However, the radiological effects have no parallel in conventional weapons. It is necessary that a conventional bomb score a direct hit or a near miss of not more than a few feet to cause significant damage to a battleship. The first bomb, bursting in air, did great harm to the superstructures of major ships within a half-mile radius, but did only minor damage to their hulls. No ship within a mile of either burst could have escaped without some damage to itself and serious injury to a large number of its crew. Although lethal results might have been more or less equivalent, the radiological phenomena accompanying the two bursts were markedly different. In the case of the airburst bomb, it seems certain that unprotected personnel within one mile would have suffered high casualties by intense neutron and gamma radiation as well as by blast and heat. Those surviving immediate effects would not have been menaced by radioactivity persisting after the burst.

The bomb to be used for the Baker test was suspended 90 feet below the surface of the lagoon in a waterproof caisson under LAM-60, which had been anchored amidst the target fleet. Crews of the target ships that had reboarded following test Able were evacuated prior to Baker and taken aboard the support fleet which sailed east of the atoll to observe the test. The Evaluation Board divided themselves into two groups to observe the Baker test, one group of four watched the test from the air at an altitude of 7.500 feet and the other three were aboard the USS Haven, which was 11 miles east of the atoll. The Baker test sank eight ships, including the battleships USS Arkansas and Nagato (captured Japanese battleship), the Aircraft Carrier USS Saratoga, the Submarines USS Apogon and USS Pilotfish, the Auxiliary craft ARDC-13, the Landing Craft LSM-60 (Surface Zero Ship), and the District Craft YO-160. The underwater detonation resulted in the majority of the target ships being doused with radioactive water and debris from the bottom of the lagoon. All but 12 of the target ships were too radioactively contaminated to be boarded for several weeks after the test, threatening the success of the test. The test produced an entirely different sort of cloud than the airburst of the first test. It was described as follows in the Preliminary Report produced by the Joint Chiefs of Staff Evaluation Board:

The visible phenomena of explosion followed the predictions made by civilian and service phenomenologists attached to Joint Task Force One. At the moment of explosion, a dome, which showed the light of incandescent material within, rose upon the surface of the lagoon. The blast was followed by an opaque cloud, which rapidly enveloped about half of the target array. The cloud vanished in about two seconds to reveal, as predicted, a column of ascending water. From some of the photographs it appears that this column lifted the 26,000-ton battleship ARKANSAS for a brief interval before the vessel plunged to the bottom of the lagoon. Confirmation of this occurrence must await the analysis of high-speed photographs, which are not yet available. The diameter of the column of water was about 2200 feet, and it rose to a height of about 5500 feet. Spray rose to a much greater height. The column contained roughly ten million tons of water. For several minutes after the column reached maximum height, water fell back, forming an expanding cloud of spray, which engulfed about half of the target array. Surrounding the base of the column was a wall of foaming water several hundred feet high. Waves outside the water column, about 1000 feet from the center of explosion, were 80 to 100 feet in height. These waves rapidly diminished in size as they proceeded outward, the highest wave reaching the beach of Bikini Island being seven feet. Waves did not pass over the island, and no material damage occurred there. Measurements of the underwater shock wave are not yet available. There were no seismic phenomena of significant magnitude. The explosion produced intense radioactivity in the waters of the lagoon. Radioactivity immediately after the burst is estimated to have been the equivalent of many hundred tons of radium. A few minutes exposure to this intense radiation at its peak would, within a brief interval, have incapacitated human beings and have resulted in their death within days or weeks….the second bomb, bursting under water, sank a battleship immediately at a distance of well over 500 feet. It damaged an aircraft carrier so that it sank in a few hours, while another battleship sank after five days. In the case of the underwater explosion, the airburst wave was far less intense and there was no heat wave of significance. Moreover, because of the absorption of neutrons and gamma rays by water, the lethal quality of the first flash of radiation was not of high order. But the second bomb threw large masses of highly radioactive water onto the decks and into the hulls of vessels. These contaminated ships became radioactive stoves, and would have burned all living things aboard them with invisible and painless but deadly radiation.

Decontamination of the target fleet was begun in earnest on the first of August. Crews of sailors from the target ships, supervised by radiation monitors, washed the ships' exteriors. The work crews were divided into shifts, each of which could only spend a very short time on board the ship due to the severe contamination. The process of decontamination resulted in radioactivity being brought aboard the support fleet by accident as well as the low levels of radioactivity in the marine growth and seawater piping systems of the vessels. On August 10 it was decided to stop the work and move to uncontaminated water to continue the process. Surviving ships of the target fleet were towed to Kwajalein during August and September where the decontamination continued. Ammunition aboard the target ships was offloaded and further decontamination efforts were made into 1947. Eight of the larger ships and two submarines were towed to the U.S. and Hawaii for intensive radiological inspection. Twelve of the ships of the target fleet were unaffected enough to be sailed back to the U.S. by their crews. The remaining target ships were destroyed by sinking off Bikini Atoll, off Kwajalein Atoll, or near the Hawaiian Islands during 1946-1948. Cost of 1946 Operation Crossroads weapons tests ("Able" and "Baker") at Bikini Atoll: $1,300,000,000.

Operation Sandstone

Conducted at Eniwetok Atoll in 1948, Operation Sandstone was the second test series done in the Marshall Islands. Sandstone consisted of three tower shots, all detonated at a height of 200 feet; X-Ray April 15, 37 kilotons; Yoke May 1, 49 kilotons; Zebra May 15 18 kilotons. It differed from the first test series in several ways: it was primarily a scientific series conducted by the Atomic Energy Commission; the Armed Forces had a supporting role in Sandstone, whereas they had assumed a lead role in Crossroads; and Sandstone was a proof-test of second-generation nuclear devices. All of the devices previously tested had been nearly identical copies of the weapon tested at Trinity and used on Nagasaki. On April 3, 1947, the General Advisory Committee to the AEC recommended development and testing of new weapons. It was time to implement some of the design changes which had been planned including a change in the core from the solid plutonium core, surrounded by a close fitting natural uranium tamper developed by Cristy to a new hollow design in which the solid core was suspended within a hollow in the tamper. The new designs did not use a pure plutonium core either. Oralloy, highly enriched uranium, was being produced in substantially larger quantities than plutonium, which made it a more attractive core material. X-Ray, used a composite oralloy-plutonium core. Both Yoke and Zebra used an all oralloy core. Other tested features included: trying different tamper thicknesses, using different amounts of fissile material in the core, and testing the effect of using a "minimum strength" polonium-beryllium Urchin neutron initiator. Urchins containing the full load of 50 curies of Po-210 had been used previously. Design parameters allowed use of initiators with as little as 12 curies however, they had not been tested. Because of the 138.4 day half life of PO-210, smaller initiators would be help in keeping stockpiled weapons available. The basic system used, the Mk 3 implosion style, was the same as the previous tests. The Mk 3 bomb used for the Sandstone devices was 60 inches in diameter and weighed 10,500 lb. total; the explosive, core and firing system weighed 7,600 lb.

When the President approved the preliminary Sandstone test program on June 27 1947, the U.S. had only 13 nuclear weapons in its stockpile. One year later, despite heavy emphasis on increased production of fissionable material, the number of weapons was only about 50, far short of the number that military planners calculated would be required in a war with the Soviet Union. The great expansion in the U.S. stockpile evident by the end of 1949 was the direct result of the higher production rates of fissionable material and the more efficient weapons designs proof-tested at Sandstone. The tests of Sandstone resulted directly in the development of the Mk 4 bomb design and the replacement of the entire U.S. weapons stockpile with bombs modeled on the designs tested. The design features tested, including the "hollow" core and using oralloy rather than plutonium for the core had both been on the drawing board since Trinity, but the positive results obtained in the Sandstone tests allowed them to be implemented. The resulting increase in yield for the weapons in the stockpile was 75%. Yields of the device in the X-ray test using a composite core were the highest to that date, but was surpassed by the wholly oralloy core in the Yoke device. The Yoke test set a record for yield that lasted until 1951.

Meetings were held on July 9, 1947 at Los Alamos, New Mexico, to define test responsibilities for Sandstone. The Los Alamos National Laboratory (LANL), the organization that had developed the wartime atomic weapons and that did research and laboratory development of new nuclear weapons designs, was to provide technical leadership and the military services were to provide supplies and support. Numerous technical experiments were conducted in conjunction with each of the three detonations. These experiments measured the yield and efficiency of the devices and attempted to gauge the military effects of the events. The studies were similar at each of the shots but were carried out more precisely with Yoke and Zebra as experience grew. Peak DOD numerical strength at Sandstone was approximately 11,500 participants, 95 percent of whom were military personnel. The DOD personnel had support roles and some had duty stations at the AEC weapons design and development laboratories or were part of units performing separate experiments.

Four U.S. vessels arrived at Eniwetok on March 16, 1948, the command ship of Joint Task Force 7 USS Mt. McKinley, the USS Curtiss a converted seaplane tender used for storage and assembly of nuclear weapons, the escort carrier USS Bairoko which carried the scientists in charge of radiological safety, and the USS Albemarle which had been refitted as laboratory space for the scientists from Los Alamos. Engebi island's vegetation had been bulldozed and construct was progressing on a 200 foot steel tower set on a 600 foot asphalt pad. Half a mile from the tower stood a reinforced concrete building built to house electronic equipment to measure the phenomena produced by the detonation. Other similar buildings placed at various distances from Zero held equipment to measure blast and radiation. Five miles southwest of the first tower on Aoman Island was a second Zero tower for the second test shot and a shorter Navy radar tower modified to hold photographic equipment. Farther south on the island of Runit was a second pair of towers for the third test shot. Ten miles farther south on Parry Island the main control center for all three shots was located across from the main island of Eniwetok. General John E. Hull was the commander of JTF7, he was headquartered on the Mt. McKinley. Captain James S. Russell was the test director and Darol K Froman the scientific director of the operation were both headquartered aboard the Curtiss. The General inspected preparations for the tests and final arrangements were completed by the Army Engineers under Brigadier General David A.O. Ogden.

On April 14th the firing party went ashore on Engebi for the final check of the circuits, and the Task Force moved south across the lagoon to prepare for the shot the next day. In the early morning the firing party left the island and sped across the lagoon aboard an aircraft rescue boat to the Parry control point. B-17 drone aircraft began taking off at -30 minutes to get in position to sample the radioactive cloud produced by the blast. The blast went off as scheduled and within four minutes helicopters were heading to Engebi and technicians in protective clothing were winching in a cable holding samples from near ground Zero. A tank was being used to gather soil samples from various points on the island by remote control. The drones were landed and the filters removed with long poles. The samples were loaded aboard a C-54 for the flight to Albuquerque. Speed was essential as some of the fission products were short lived. By flying them in relays, rather like the Pony Express, the samples reached Los Alamos within 30 hours. Levels of radioactivity on Engebi were low enough in a few days for the scientists to go ashore and recover the test equipment. The second and third shots were done the same way on May 1st and 15th . It took only a few days for scientists to remove the equipment and within a week the support forces were closing down the site.