Naval Radiological Defense Laboratory (NRDL) Briefing Book

by Kevin Chen, Research Assistant


            Located at the Hunters Point Naval Shipyard from 1946 to 1969, the Naval Radiological Defense Laboratory (NRDL) was a research facility that studied the effects of radiation. The military initially established NRDL to address the problem of radioactive ships returning from Operation Crossroads, a pair of nuclear tests conducted in the Pacific. The tests not only underscored the destructive physical power of the bomb, but also demonstrated the threat to nuclear security posed by long-lasting radioactive contamination.

            In this new era of warfare, the military tasked the laboratory with devising methods for decontaminating the ships. With increased funding and sponsorship secured by the urgency of its mission, NRDL’s scope expanded to encompass basic and applied biological, chemical, and physical studies of radiation. The research conducted by the laboratory supported national security objectives by producing basic knowledge of radiation as well as practical measures to mitigate its effects on and off the battlefield.

Figure 1: Naval Radiological Defense Laboratory Building 815, 1955. Source: San Francisco Public Library,

            In 1969, the Navy shuttered the laboratory, closing a chapter of Cold War history. While public memory of NRDL has been shrouded by government secrecy and historical amnesia, it continues to make itself known through its toxic legacy. Radioactive substances from the laboratory were poured down drains, released into the air, and discarded into landfills. Thousands of barrels of radioactive waste from experiments were dumped off the Farallon Islands, located 30 miles from the California coast. With the redevelopment of Hunters Point underway, the toxic soils where NRDL once stood comprise the material residues of nuclear insecurity in the Bay Area and beyond.

Operation Crossroads and the Birth of Radiological Warfare

            In July 1946, the United States Army and Navy jointly conducted Operation Crossroads, the first nuclear tests performed after the bombings of Hiroshima and Nagasaki.[1] Marshalling massive amounts of military and scientific resources, Operation Crossroads became a defining moment in global nuclear history, invigorating debates over international control of atomic energy and the scientific value of nuclear tests. The tests precipitated a radiological crisis that not only led to a greater awareness of radiation hazards, but also revealed the military’s lack of preparedness for addressing those hazards.

Figure 2: Bikinians leaving Bikini Atoll in preparation for Operation Crossroads, 1946. Source: NARA, Still Pictures Unit, Record Group 374-G, box 7, folder 60 “Tests: Operation Crossroads.” Retrieved at

            After the bombings of Hiroshima and Nagasaki, debates heated up over the relative importance of naval versus air power in the military. The destructive capabilities of the bomb ushered in a new era of warfare, one that naval commanders feared could make the navy obsolete. If the bomb could wipe out cities, then ships stood little chance of survival. Additionally, if the bomb could be delivered by plane, then the military would stand to gain a competitive advantage by strengthening its air force. Underlying these debates was a deep sense of national insecurity: a profound feeling of vulnerability provoked by the awesome power of the bomb.[2]

            In this context, American military planners proposed Operation Crossroads to assess the effects of the bomb on existing military assets and operations. The tests would determine the changes that the military needed to make in training, strategy, and equipment to prepare for nuclear war. The tests would also settle the debates between the Navy and the Armed Air Forces over whether a naval fleet could survive a nuclear explosion. After President Truman approved Operation Crossroads, the Army and Navy convened Joint Task Force One, with Rear Admiral William H. P. Blandy leading as the director. The task force selected Bikini Atoll in the Marshall Islands as the test site because of its relative isolation from population centers, reassuring the 167 Bikinians that they would be able to return home after the tests.[3]

            Widespread concern over the safety and utility of Operation Crossroads, however, animated public opposition from civilians, scientists, and politicians from the start. At the time, the United Nations was attempting to formulate a system of international control of atomic energy. Disagreements between the United States and the Soviet Union over verification and disarmament measures heightened tensions between the two former wartime allies. Critics argued that Operation Crossroads signaled that the United States was not seriously interested in controlling nuclear proliferation. Others worried that the explosions could have unintended catastrophic consequences on the magnitude of massive earthquakes and tidal waves. Some civilian scientists, including those who formerly worked on the Manhattan Project, argued that the tests had little scientific value, lending support to the notion that the tests were a wasteful military exercise rather than a legitimate experiment.[4]

Figure 3: Goats on ship deck prior to Shot Able. Source: NARA, Still Pictures Unit, Record Group 374-G, box 7, folder 60 “Tests: Operation Crossroads.” Retrieved at

            The task force developed an extensive public relations campaign to counter these criticisms. It emphasized the tests’ scientific aspects and asserted that the tests were completely unrelated to current negotiations over the control of atomic energy. Indeed, it argued that in the absence of such control, the military had a responsibility to study the effects of nuclear weapons to maintain national security. Although the United States government kept much of Operation Crossroads secret, it invited members of the press and foreign observers from the United Nations Atomic Energy Commission (UNAEC) to the tests. As a mass-mediated event, Crossroads became a large-scale exercise in managing public opinion.[5]

            The practical organization of the tests was a massive logistical undertaking, involving over 40,000 military and civilian personnel divided into eight task groups, covering photography, instrumentation, and more. Researchers spanning the disciplines of botany, seismology, and radiology contributed to the effort. Over 10,000 instruments were placed on ships, islands, and aircraft surrounding Bikini, calibrated to produce radiometric, oceanographic, and electromagnetic data from the explosions. Nearly 100 battleships, aircraft carriers, and other vessels declared as obsolete by the Navy were prepared at Hunters Point and other naval shipyards as test targets. Over 5,600 goats, pigs, guinea pigs, mice, and rats were placed in compartments and strapped onto ship decks to evaluate the biological effects of the bomb.[6] Led by Stafford Warren, the former medical director of the Manhattan Project’s medical section, the Radiological Safety (“radsafe”) Section was a corps of 300 monitors that was responsible for protecting personnel from radiation hazards. Warren set the permissible dose of radiation at 0.1 roentgen per day, equivalent to the limit for manufacturing plants in the United States at the time.

Figure 4: Shot Baker nuclear test, 1946. Source: Galerie Bilderwelt/Getty Images. Retrieved at

            On July 1, 1946, the first bomb, Shot Able, was dropped, exploding nearly half a mile off target and inadvertently destroying much of the instrumentation intended to gather data from the detonation. The test disappointed members of the press, who expected a visceral experience of the shock wave. Notwithstanding these perceptions, the explosion still demonstrated the overwhelming power of the bomb by leaving the superstructure of the aircraft carrier USS Independence mangled and unrecognizable.[7] On July 25, the second bomb, Shot Baker, was detonated 90 feet underwater, generating a massive dome of condensation and an iconic cauliflower-shaped water column. Nearly half a mile across, the column rose for 8,000 feet before collapsing back into the lagoon, spawning a wave of mist and debris that came to be known as a “base surge.” In addition to the phenomenal damage inflicted by the physical force of the explosion, the base surge drenched the target ships with extraordinary amounts of radiation. Unlike previous explosions conducted in the air or over land, most of the fallout released by Shot Baker did not dissipate into the atmosphere. Rather, it spread throughout the air in highly radioactive water droplets.[8]

Figure 5: Group of sailors wash down the deck of the USS Prinz Eugene after the Shot Able test, 1946. Source: NARA, Still Pictures Unit, Record Group 80-G, box 2228, folder 627483-627519. Retrieved at

            Shot Baker thus precipitated one of the worst radiological crises in American history. One hour after detonation, radiation levels at the explosion site were equivalent to the amount emitted by 5,000 tons of radium. When Admiral Blandy attempted to board a target ship the following day, he was forced to leave after less than 30 minutes because of high radiation levels. Despite the significant resources devoted to Operation Crossroads, Joint Task Force One had not prepared for contamination of this magnitude. Ship crews were responsible for decontaminating their respective vessels back to operational use. The problems of the decontamination effort, however, were legion. Naval personnel tried washing the ships with water, detergent, ground coffee, sand, and more, none of which worked to significantly reduce radioactivity. Technical difficulties worsened the situation. The radsafe section’s primary instrument for measuring radiation, the X-263 Geiger counter, malfunctioned in the hot and humid climate. Moreover, the device only measured beta and gamma radiation, leaving lethal alpha radiation in the form of plutonium undetected.[9]

            Conflicting priorities between the radsafe personnel and the ship crews exacerbated radiation hazards. Warren was preoccupied with ensuring that the ships were safe enough to board, which, given the ineffectiveness of decontamination efforts, meant waiting for radioactivity to decay with time. But the crews wanted to board the ships as soon as possible to return them to use. As a result, crew members, most of whom received minimal or no radiological safety training, failed to follow the radsafe guidelines. Men slept and ate aboard contaminated ships, exposing them to internal radiation. Though radsafe personnel wore protective clothing and gear, crew members did not. The radiation also spread to support ships that were not directly exposed to fallout from the tests. Upon entering the still-radioactive waters of the lagoon, the ships crews turned on evaporators, which contaminated the internal pipes of the ships with radioactive seawater. The radsafe personnel found that marine life attached to ship hulls, such as barnacles and algae, concentrated radioactivity.[10]

            Recognizing that the decontamination effort at Bikini could not continue without placing personnel in serious danger, Warren convinced Blandy to halt the decontamination work. The contaminated ships were transported to the naval base at Kwajalein Atoll. Of these, twenty of the most damaged ships were towed to naval shipyards for further inspection and decontamination. Mangled but still floating, the Independence was among the six transported back to Hunters Point Naval Shipyard, where they became experimental specimens for developing decontamination methods.

Crossroads at Hunters Point, 1946-1948

Figure 6: Navy workman sandblasting side of submarine, 1947. Source: Fritz Goro/The LIFE Picture Collection via Getty Images. Retrieved at

            In response to these crises in knowledge and authority, the military established a scientific research program at Hunters Point that later became NRDL. After Operation Crossroads, the Navy’s Bureau of Ships established the Radiological Safety Section (RSS) at Hunters Point Naval Shipyard in 1946. Originally consisting of a dozen radsafe personnel returning from Bikini, the RSS was responsible for continuing the work of decontaminating the ships.[11] The Bikini tests demonstrated that long-lasting radioactivity from the bomb could incapacitate entire crews, even if the explosion left ships intact. Radioactive contamination from fallout thus became a new object of concern for the military, signaling a changing conception of security in the Nuclear Age. In the shadow of this new threat, the RSS produced knowledge that would allow the military to maintain permanent readiness and continue operating through the radiological hazards of atomic war.

            Out of these investigations, the Navy established a laboratory for radiological studies, commonly referred to as the “Rad Lab,” at Hunters Point.[12] As the predecessor to NRDL, the laboratory’s early studies and experiments focused on the immediate problems presented by the contaminated ships returning from the Pacific. On a trial-and-error basis, personnel tested methods of decontaminating ships using detergents, acid solutions, and scrubbing, with varying degrees of success. They settled on using wet sandblasting to decontaminate ship hulls and acid solutions to clean internal pipe systems. The laboratory also investigated other problems of radiological contamination presented by the ships. 610,000 gallons of contaminated fuel from target ships were burned in the shipyard power plant to measure the alpha radiation in the fumes.[13] Researchers converted the Independence into a floating laboratory at the shipyard, where they continued to experiment with decontamination methods and techniques.[14] Because of the knowledge and expertise developed at the shipyard, Hunters Point became the Navy’s hub for monitoring and clearing ships returning from Bikini. In the months following Operation Crossroads, an additional 18 target ships and 61 support ships were decontaminated at the shipyard.[15]The laboratory was also tasked with developing instruments that could detect radiation with greater accuracy and precision, especially in field conditions.

Figure 7: USS Independence docked at Hunters Point Shipyard after Operation Crossroads. Source: NARA. Retrieved from “Post-Crossroads History of the Ex-USS Independence: Recently Declassified Documents and Images,” Journal of Maritime Archaeology 11 (April 2016): 35–126,

            The purpose of the laboratory was elaborated in its first official mission in 1947, which emphasized the “opportunities for technical investigations offered by the vessels participating in Operation Crossroads” in the “research and development of radiological problems of atomic warfare.”[16] The Navy sited the laboratory at Hunters Point for three reasons. First, the shipyard already berthed contaminated vessels from Operation Crossroads. Second, San Francisco’s strategic location would serve as a launching point for future nuclear tests.[17] Third, Hunters Point was conveniently located near two premier research institutions: University of California, Berkeley and Stanford University. In particular, Ernest O. Lawrence’s Radiation Laboratory at Berkeley served as an existing hub of radiological expertise that the Navy sought to emulate. In the early years of the Hunters Point Rad Lab, the Navy frequently consulted the Berkeley laboratory for technical support.[18] In November 1946, military officials consulted Dr. Joseph Hamilton, a biomedical expert in radiation, on safety procedures for decontaminating ships returning from Crossroads. Hamilton, who later became infamous for human plutonium injection experiments, stated that waste from the decontamination efforts could be dumped into San Francisco Bay without harm to human health.[19]

            The Rad Lab initially faced significant technical and administrative challenges. To carry out its mission, the laboratory needed to secure space, equipment, funding, and personnel. From its beginnings in a “rented room” at the shipyard, the laboratory moved into the former shipyard dispensary, which came to house chemistry laboratories, an instrument repair room, storage rooms, and administrative offices.[20] The rapidly expanding laboratory swallowed up barracks and storage rooms, crowding up against ship maintenance and repair facilities. Furthermore, the Navy quickly realized that it needed academic experts in physics, chemistry, and biology to carry out its studies. The first organizational chart, published in 1947, separated administrative functions, led by Navy officers, and the technical program, led by civilian scientists. Hiring began in March 1947 and a year later, the laboratory had 142 employees, including 56 professional civilians.[21]

Expanding NRDL, 1948-1958

            On April 21, 1948, the laboratory was officially christened as the Naval Radiological Defense Laboratory. That year, the laboratory revised its mission statement: “To conduct investigations and develop information concerning effects and consequences of dispersed fissionable materials, fission products or other radioactive substances.”[22] In 1950, NRDL was separated as a distinct activity from Hunters Point Naval Shipyard, though it remained under the direction of the shipyard commander. The mission was further adjusted: “To conduct basic and applied research and development concerned with the radiological safety program of the Armed Forces; investigate the effects and consequences of dispersed fission products, fissionable materials, and other radioactive substances present and resulting from nuclear processes on ships at sea, in harbors and anchorages, and in shore establishments; and determine and develop corrective measures for the foregoing.”[23] In 1955, NRDL was detached entirely from the shipyard and placed under its own independent command. Reflecting external recognition of its expertise, the mission stated that the laboratory would “act as a primary consultant and adviser in the field of defense against nuclear weapons and protection to all branches of the Defense Department, and as occasional consultant to the Atomic Energy Commission, U.S. Public Health Service, civil defense organizations, and others.”[24]

            Accompanying NRDL’s growing mandate was a simultaneous expansion of space, resources, equipment, and funding. During this period, the laboratory received increasing amounts of sponsorship from government agencies ranging from the Armed Forces Special Weapons Project to the Army Corps of Engineers. In 1951, the core structure of NRDL was cemented with the establishment of four departments: Scientific, Administrative, Management Engineering, and Medical Services. The Scientific Department was further subdivided into four divisions: biological and medical, chemical technology, nucleonics, and military evaluations.[25] This basic structure remained intact until 1966, when the divisions were split into basic and applied research sections. Boosted by increases in Cold War defense funding, the size of the staff more than doubled to over 600 members between 1950 and 1952.[26] In 1955, the laboratory completed construction of a new six-story building, costing $8 million. The building, which still stands today, contains 282,000 square feet of space and centralized much of the laboratory’s activities.[27]

            The Biological and Medical Sciences Division conducted animal experimentation to assess, evaluate, and prevent radiation injury in humans.[28] Scientists measured the biological effects of exposure from different sources of radiation, such as gamma rays, neutron radiation, and beta particles, at varying dosages, rates, and exposure pathways. The effects examined included skin burns, gastrointestinal damage, and effects on the central nervous system. Biologists also studied the variables that affected recovery from radiation, such as shielding provided by physical barriers and the age of specimens at time of exposure. To devise potential treatments for radiation injury, researchers studied the factors that determined acceptance or rejection of skin grafts and bone marrow transplants.

            The Chemical Technology Division investigated the physical and chemical characteristics of fallout and developed techniques for reducing contamination. Chemists studied the size,  shape, and composition of fallout particles, which were crucial factors in the dispersal and distribution of contamination from a nuclear detonation. On a fundamental level, researchers sought to clarify the sequence of chemical reactions that occurred during nuclear explosions to better understand the decay chain of fission products. These data informed radiological countermeasures devised by the military by specifying the most effective method of decontamination with a given type of detonation and its associated pattern of fallout.

Figure 8:. Men preparing fallout collector tray at Operation Castle, 1954. Source: NARA,

            The Nucleonics Division studied the characteristics of nuclear reactions and developed radiation detection instrumentation for use in the combat settings. Scientists tested the suitability of different materials in constructing more precise instrumentation. Physicists also conducted shielding studies to evaluate the effects of both thermal and nuclear radiation on different materials, with the aim of quantifying the amount of protection offered by structures during a nuclear explosion. In 1966, the Nucleonics Division was separated into the Radiation Physics and Physical Sciences divisions. The latter conducted basic research into the nuclear and radiological physics, whereas the former conducted applied research, continuing to develop radiation detection instruments.

            The Military Evaluations Division synthesized scientific knowledge for military applications, bridging the gap between experimental results and military operations in the form of tactical doctrine and manuals. The Military Evaluations Division thus performed NRDL’s primary function within the broader project of Cold War military science: to align technical and military knowledge of radiation. The division published manuals like Radiological Recovery of Fixed Military Installations, which summarized information on reclaiming military sites contaminated by fallout, and Principles of Radiation and Contamination Control, which covered techniques for measuring and minimizing radiation exposure to personnel.

Figure 9: Man collecting samples aboard research vessel for Operation Redwing, 1956. Source: NARA,

            Paralleling its production of both basic and applied knowledge, NRDL conducted its research in both laboratory and field settings. Indeed, much of its work relied on moving between the laboratory and the field as distinct yet interconnected sites for producing and validating knowledge.[29] Whereas the laboratory provided a controlled setting for isolating experimental variables, the field served as a proving ground for testing the validity and applicability of laboratory models in a real-world setting. From 1950 to 1958, NRDL conducted field studies at the nuclear tests at the Pacific and Nevada test sites.[30] Many of these studies involved collecting samples of fallout for laboratory analysis at Hunters Point. The data they collected were used to generate models of radiological contamination resulting from a nuclear detonation, to predict the effects of fallout on military and civilian installations, and to devise effective decontamination methods in the event of an attack.[31] At the same time, the laboratory’s original expertise in ship decontamination continued to prove useful in nuclear tests; ships that participated in the tests returned to the shipyard for decontamination.[32] In this way, the material circulation of radioactive fallout and scientific knowledge incorporated Hunters Point and the Marshall Islands into transpacific nuclear geographies.[33]

Figure 10: Dr. Robert Conard examining Marshallese boy for beta burns from radioactive fallout from Castle Bravo, 1954. Source: NARA,

            A watershed moment in NRDL’s history was Operation Castle in 1954, which, as the Navy notes, “gave a new dimension to the fallout problem, and the tremendous area of hazards made a profound impression.”[34] Castle Bravo was the most powerful bomb ever exploded by the United States, releasing 15 megatons of energy, more than double the predicted yield. Because of wind conditions and the unexpectedly high yield, Castle Bravo produced massive amounts of white, snow-like fallout that contaminated inhabited atolls to the east, as well as the Lucky Dragon, a nearby Japanese fishing boat.[35] As a result, hundreds of Marshall Islanders were exposed to high levels of radiation, causing skin burns, radiation sickness, and chronic health problems. In the immediate aftermath, researchers from NRDL and the Naval Medical Research Institute (NMRI) conducted health surveys of the exposed Marshallese population. Blurring the distinction between military exercise and scientific experimentation, the United States government took advantage of the disaster to initiate Project 4.1, a long-term study of the health effects of radiation on the exposed Marshall Islanders.[36] In this way, the collateral damages of Castle Bravo, much like the unintended catastrophe of Operation Crossroads, reiterated the urgency of NRDL’s mission and opened new avenues of research into the radioactive aftermaths of nuclear war. Against assertions that the United States has never experienced nuclear war, these two disasters served as templates for imagining and managing the ruins of a radioactive America.[37]

             In this way, NRDL’s scientific program aligned divergent categories of knowledge, expertise, and experimentation. The enactment of this expertise took place in similarly diverse settings. In the realm of military operations, NRDL’s expertise took the form of technical reports, memoranda, plans, trainings, doctrines, and manuals. At the Damage Control School on Treasure Island, NRDL’s Radiological Safety Officer provided lectures to students enrolled in radiological safety courses.[38] NRDL thus translated between scientific and military knowledge, mediating different forms and practices of knowledge production. Its expertise also influenced scientific and academic circles beyond the military. NRDL researchers published in peer-reviewed journals such as Radiation Research and attended conferences with scientists from universities and other government laboratories. NRDL was thus one example of the entanglement of scientific research and the national security apparatus during the Cold War.[39]

Beyond the Nuclear Testing Regime, 1958-1969

            In 1958, the United States and Soviet Union announced a moratorium on nuclear testing that lasted until 1961. During this time, American and Soviet diplomats attempted to negotiate a treaty to limit nuclear testing, though disagreements over verification measures and other terms of a test ban eventually caused the moratorium to collapse. Afterwards, the United States and Soviet Union conducted a flurry of tests, with the latter detonating Tsar Bomba, the most powerful bomb ever built. On the American side, scientists from NRDL participated in Operation Sunbeam at Nevada and Operation Dominic in the Pacific, the last two atmospheric nuclear tests conducted by the United States. In 1963, the two countries signed the Partial Test Ban Treaty, spurred in part by public outcry over the harmful effects of fallout. As a result, nuclear testing in the United States moved underground at the Nevada Test Site, curtailing NRDL’s access to its primary field test sites. Rather than merely shifting their research toward more laboratory-based experiments, however, scientists at NRDL developed sophisticated techniques for simulating nuclear explosions and fallout. In this way, the laboratory actively sought to blur the boundary between real and simulated nuclear war.[40]

            To implement this new regime of experimentation, the laboratory began conducting large-scale studies at Camp Stoneman and Camp Parks in rural Contra Costa County, which provided ample open space for field tests. In 1956 and 1958, NRDL researchers spread sand laced with radioactive tracers across Camp Stoneman, located in Pittsburg, to test methods of reclaiming land contaminated with fallout.[41] Recognizing the need for a site that could accommodate other large-scale field studies, the laboratory built a field station at Camp Parks in 1958, approximately 13 miles west of Livermore. The field station at Camp Parks came to occupy a pivotal role in the laboratory’s operations, supplementing the laboratory’s facilities at the shipyard. In 1959 and 1960, NRDL personnel followed up on the earlier Camp Stoneman studies, dispersing tons of sand tagged with lanthanum-140 across four acres of a simulated American neighborhood, complete with streets, lawns, and shrubbery. The sand was left in place for ten days to allow researchers to track the movement of contaminants over time. Using hoses, bulldozers, plows, and other tools, decontamination crews tested methods of removing radioactivity from surfaces.[42]

            Camp Parks also became home to a colony of large animals, such as sheep, cows, and goats, used in biological experiments on the effects of radiation on large animals. In 1963, the laboratory constructed an animal testing facility, built by inmates from the neighboring Santa Rita Jail, that used 15,000-curie cobalt-60 sources in biological experiments and shielding studies. The field station also contained a range area for testing radiation detection instruments. The laboratory built a test facility to disperse water droplets tagged with radioisotopes on different construction materials, simulating radioactive seawater fallout from an underwater detonation.[43]

            During the moratorium, NRDL initiated the HYDRA program, a series of experiments that used explosives and radioactive tracers to track the radiological effects of underwater detonations.[44] Initially, the tests were conducted at an 18-foot test pond constructed at the Camp Parks field station. The laboratory later followed up on these pilot tests with large-scale experiments at San Clemente Island using 10,000-pound explosives. Using high-speed motion cameras, laboratory scientists tracked the shock wave and bubble structure created by the explosions. They developed gamma probes to measure and map the radiation that was released into the air and absorbed into the water. By quantifying the physical, chemical, and radiological qualities of underwater nuclear explosions in exacting detail, researchers sought to specify the precise mechanisms by which underwater detonations dispersed radiation.[45]

Figure 11: A copy of a December 1959 photograph of a Naval Radiology Defense Laboratory fallout shelter experiment copied at the Alameda County Sheriff’s office archives in Dublin, on Aug. 22. This photo shows everybody outside of the shelter. Source: Dan Honda/Bay Area News Group. Retrieved from

            During the same period, NRDL also began conducting civil defense studies. In 1956, NRDL scientists provided expert testimony to Congress in support of a national fallout shelter system. The Office of Civil Defense Mobilization (OCDM) later sponsored studies that led to the development of a model fallout shelter. In December 1959, NRDL conducted an occupancy test of the shelter at Camp Parks with 92 male prisoners from the neighboring Santa Rita Jail. Over the course of two weeks, NRDL researchers observed life within the shelter, examining the prisoners’ reactions to confinement and studying the suitability of the food rations supplied by the Department of Agriculture. The following year, NRDL conducted a follow-up 48-hour long occupancy test involving 100 civilian volunteers.[46]

            In 1960, NRDL expanded its mission to include the study of “nuclear and thermal radiation from nuclear explosions, natural and controlled processes, and nuclear accidents and incidents.”[47] Importantly, the revised mission included radiation exposure from both nuclear weapons and from non-weapon sources. This revision signaled the broadening horizons of NRDL’s scientific program as the nation’s nuclear capabilities and priorities shifted in the post-atmospheric testing era. The laboratory embarked on field tests and trips that, like nuclear tests at the Pacific and Nevada test sites, took it far beyond the Bay Area. In 1964, researchers traveled to Costa Rica to test the effectiveness of filters in preventing ash from a volcanic eruption from entering buildings. The same year, an engineer traveled to Alaska to evaluate the recovery efforts after the 9.2 magnitude Good Friday earthquake, the results of which informed reclamation procedures in the aftermath of a nuclear attack.[48] In the following years, NRDL initiated a series of studies of the potential radiological hazards resulting from an accidental release of fissile material from nuclear-propelled vehicles as part of the Systems of Auxiliary Nuclear Power (SNAP) program.[49] In 1965, NRDL established a field station at San Clemente Island, located off the coast of southern California, where researchers measured the corrosion rate of SNAP systems exposed to seawater.[50]

            In response to changing defense priorities and funding sources in the latter half of the 1960s, the laboratory sought to redefine its scientific program toward a broader mission of applied research. By 1965, the laboratory saw that “solution to many radiological defense problems is in sight,” foreshadowing a decline in interest and funding in what had been the laboratory’s primary object of study.[51] Two years later, a study group convened to propose an alternative mission: “To prosecute a fundamental and applied science program in nuclear, biological, and chemical warfare, and in non-weapon nuclear energy applications.”[52]

Shutting Down NRDL

            In April 1969, the Department of Defense ordered the closure of the laboratory by the end of the year. The Navy argued that it would save an estimated $7.6 million a year from closing the lab.[53] The announcement galvanized a campaign among NRDL staff to save the laboratory. They argued that the closure would not actually save money for the Navy because most of the laboratory’s government-sponsored research funding would be transferred to other facilities. Indeed, the scientists suggested that the closure could increase costs by wasting investments in laboratory equipment, assets, and facilities, such as the recently completed 14,800 square foot Animal Research Facility. At the same time, the scientists were concerned that the laboratory’s closure would permanently disrupt research networks anchored at NRDL. Though the Navy arranged for the transfer of high-ranking scientists to other laboratories, some were concerned existing research teams and projects would be displaced, causing irrevocable damage to both institutional networks and individual reputations.

            The laboratory’s scientists proposed converting NRDL into a federal environmental research facility, shifting its focus to civilian research. In an interview with the San Francisco Chronicle, Dr. William E. Kreger, head of the Physical Sciences Division, listed a range of potential research projects that the laboratory could undertake, such as the health effects of air pollution.[54] Not only would these projects draw on the expertise and knowledge that scientists already cultivated through previous research, but they would also neatly fit into the existing work of civilian agencies. The scientists gained the support of Bay Area congressional representatives and successfully lobbied the Department of Health, Education and Welfare to look into taking over the laboratory.[55] In the end, however, the Navy moved ahead with the closure of the laboratory, closing a chapter of Cold War military science.

Radioactive Legacies of the Cold War

Figure 12: Map of Farallon Islands Nuclear Waste Site. Source: U.S. Geological Survey. Retrieved from “Measurement of seafloor radioactivity at the Farallon Islands radioactive waste dump site, California,” (2001),

            Many of the buildings that NRDL occupied still stand in the shipyard today. As monuments of a vast scientific enterprise sustained by Cold War national security imperatives, they comprise the physical remnants of a laboratory that once led the nation in cutting-edge radiation research. The air, water, and soil of the shipyard, however, also serve as material archives of less visible, yet equally durable legacies of the lab. NRDL left behind untold amounts of radioactive contamination at the shipyard, currently designated as the only Superfund site within San Francisco.[56]

            Throughout the laboratory’s existence, the Health Physics Division was responsible for implementing radiological safety protocols. The division monitored personnel exposure and routinely surveyed areas where radioactive materials were used. The division also handled the disposal of radioactive waste from the laboratory until 1959, after which waste disposal was contracted out to a private company. Between 1946 and 1965, the Hunters Point Naval Shipyard served as a hub for radioactive waste disposal from NRDL, Lawrence Livermore National Laboratory, the Lawrence Radiation Laboratory at University of California, Berkeley, and other facilities that produced radioactive waste in the Bay Area. Waste from these facilities was transported to the shipyard, sealed in 55-gallon steel barrels, loaded onto barges, and dumped off the Farallon Islands, located 30 miles off the coast in the Pacific Ocean.[57]

Figure 13: USS Independence being used as a naval gunfire target and sunk in the Pacific Ocean, 1951. Source: NavSource Naval History,

            The waste site, estimated to cover 1,400 square kilometers of the seabed, lies within the boundaries of the Greater Farallones National Marine Sanctuary (GFNMS), home to diverse marine wildlife.[58] The government estimates that 47,500 barrels of waste containing 14,500 Ci of radioactive material were sunk there.[59] The waste site is also the final resting place of the Independence, which was loaded with barrels of waste and sunk in an explosives test in 1951.[60] The exact amounts and types of radioactive substances dumped at the site remain unknown. According to the EPA, the barrels most likely contained low-level radioactive waste, such as clothing, paper towels, and lab equipment that came into contact with short-lived radioisotopes during experiments.[61] The use of highly toxic radioactive isotopes at NRDL, such as plutonium, has raised concerns, however, that these materials might have also been dumped.[62] In the 1970s, the Environmental Protection Agency (EPA) and NOAA began conducting surveys to measure the amount of radioactivity being released into the environment and to assess the risk posed to human health. From these studies, these agencies have stated that the waste poses no risk to human health or the environment, despite alternative interpretations of the data.[63] One study conducted by scientists from the University of Washington in 1977 found elevated levels of cesium and plutonium in sediment and fish samples, but not in the edible muscle tissue that is usually consumed.[64] A decade later, researchers from the University of California, Davis found extremely high levels of plutonium and americium in bottom-feeding fish, many times over the levels measured in the 1977 and other previous studies.[65]

            In 1990, the U.S. Geological Survey and NOAA conducted the most comprehensive survey of the site to date, using underwater submersibles and sonar to map the locations of barrels across 200 square kilometers, or 15 percent, of the site.[66] A subsequent gamma-ray scan of the seabed was conducted in 1998 to obtain a regional overview of radioactivity at the site.[67] The scan found slightly elevated levels of cesium, americium, and plutonium in the sediment around barrels, substantiating previous findings that radioactivity could be leaking into the marine environment. According to the researchers, however, the radioisotope concentrations were well below the threshold for concern and posed no health risk to humans. At the same time, the survey only covered the shallower portions of the waste site, even though over 90 percent of the barrels are estimated to have been dumped in deeper waters.

Figure 14: Comparison of historical photo of USS Independence with low-resolution sonar image of shipwreck. Source: National Oceanic and Atmospheric Administration,

            In 2015, marine archaeologists from NOAA rediscovered the wreck of the Independence near the Farallon Islands.[68] Though the government had been aware of its general location since scuttling it in 1951, its precise resting place had remained unknown. Measurements of radioactivity conducted in conjunction with the archaeological survey did not find significant amounts of radioactivity in samples collected from the shipwreck.[69] Nevertheless, the rediscovery of the Independence nearly 70 years after Operation Crossroads is a reminder of the material legacies of the Nuclear Age as they unfold in the present.

[1] For a comprehensive history of Operation Crossroads, see Jonathan M. Weisgall, Operation Crossroads: The Atomic Tests at Bikini Atoll (Annapolis, MD: Naval Institute Press, 1994).

[2] Ibid., 11–17.

[3] Ibid., 31–33, 106–114. The islands had been occupied by the U.S. military since World War II when the United States captured them from Japan.

[4] Ibid., 64, 73–74, 98–99, 153–162.

[5] Ibid., 117, 159–162.

[6] Ibid., 116–123.

[7] Ibid., 185–191, 195.

[8] Ibid., 221–225, 227.

[9] Ibid., 209–214, 227, 228, 230.

[10] Ibid., 229–232, 235–237.

[11] United States Naval Radiological Defense Laboratory, “History of the U.S. Naval Radiological Defense Laboratory, 1946–1958,” (1959), 1.

[12] Ibid., 2.

[13] U.S. Navy, “Hunters Point Shipyard Final Historical Radiological Assessment,” 6-18.

[14] Ibid., 6-24. The Independence left Kwajalein on May 15, 1947 and arrived at Hunters Point on June 16, 1947.

[15] To receive final clearance by the Navy, the ships were required to measure no more than 0.005 roentgen per day overall and 0.001 roentgen per day in saltwater piping systems. Ibid., 242, 274-275; United States Navy, “Hunters Point Shipyard Final Historical Radiological Assessment: History of the Use of General Radioactive Materials 1939–2003” (2004), 6-17,

[16] USNRDL, “History, 1946–1958,” 3.

[17] USNRDL, “History, 1946–1958,” 2.

[18] Dillon, “Crossroads in San Francisco,” 81.

[19] Weisgall, Operation Crossroads, 273. On plutonium injection studies and other human radiation experiments in the United States, see Eileen Welsome, The Plutonium Files: America’s Secret Medical Experiments in the Cold War (New York: Dial Press, 1999).

[20] Ibid., 19.

[21] Ibid., 16.

[22] Ibid., 3–4.

[23] Ibid., 4.

[24] Ibid., 3–5.

[25] Ibid., 8.

[26] Ibid., 16.

[27] Ibid., 20.

[28] Ibid., 28–30. On animal experiments involving radiation conducted at the University of California, Davis, see Brad Bolman, “Strontium,” Theorizing the Contemporary, Fieldsights (June 27, 2019), On the history of radioisotopes in biological research and medical applications, see Angela N. H. Creager, Life Atomic: A History of Radioisotopes in Science and Medicine (Chicago: University of Chicago Press, 2013). On the history of radiation exposure research in other contexts, see Soraya Boudia, “From Threshold to Risk: Exposure to Low Doses of Radiation and its Effects on Toxicants Regulation,” in Toxicants, Health and Regulation since 1945, eds. Boudia and Nathalie Jas (London, Pickering & Chatto, 2013), 71–88; Donna M. Goldstein and Magdalena Stawkowski, “James V. Neel and Yuri E. Dubrova: Cold War Debates and the Genetic Effects of Low-Dose Radiation,” Journal of the History of Biology 48, no. 1 (July 2014): 67–98,; Susan Lindee, Suffering Made Real: American Science and the Survivors at Hiroshima (Chicago: University of Chicago Press, 1994).

[29] See Jeremy Vetter, ed., Knowing Global Environments: New Historical Perspectives on the Field Sciences (New Brunswick, NJ: Rutgers University Press, 2010).

[30] For a first-person account of NRDL’s participation in nuclear tests, see Rod Buntzen, The Armageddon Experience: A Nuclear Weapons Test Memoir (Bloomington, IN: Xlibris, 2019).

[31] On how US nuclear testing in the Marshall Islands created opportunities for other forms of scientific knowledge production, specifically in the field of ecology, see Elizabeth DeLoughrey, “The Myth of Isolates: Ecosystem Ecologies in the Nuclear Pacific,” Cultural Geographies 20, no. 2 (October 2012): 167–184,; Laura J. Martin, “Proving Grounds: Ecological Fieldwork in the Pacific and the Materialization of Ecosystems,” Environmental History 23, no. 3 (July 2018): 567–592,

[32] U.S. Navy, “Hunters Point Shipyard Final Historical Radiological Assessment,” 6-25, 6-26.

[33] These geographies included other sites of nuclear production and contamination, such as the Nevada Test Site. On the contamination of the Marshall Islands, see Ruth Levy Guyer, “Radioactivity and Rights: Clashes at Bikini Atoll,” American Journal of Public Health 91, no. 9 (September 2001): 1371–1376,; Johnston and Baker, Consequential Damages. On contamination at Hunters Point, see Lindsey Dillon, “Race, Waste, and Space: Brownfield Redevelopment and Environmental Justice at the Hunters Point Shipyard,” Antipode 46, no. 5 (November 2014): 1205–1221, On contamination from the Nevada Test Site, see Valerie Kuletz, The Tainted Desert: Environmental Ruin in the American West (New York: Routledge, 1998).

[34] USNRDL, “History, 1946–1958,” 34.

[35] For a first-person account from a crewmember of the Lucky Dragon, see Oishi Matashichi, The Day the Sun Rose in the West: Bikini, the Lucky Dragon, and I (Honolulu, HI: University of Hawaii Press, 2011).

[36] For a detailed account of the damages of Castle Bravo to Marshall Islanders, including medical experimentation, see Barbara Rose Johnston and Holly M. Baker, Consequential Damages of Nuclear War: The Rongelap Report (Walnut Creek, CA: Left Coast Press, 2008). On the use of environmental legislation by the Marshallese to seek compensation, see Mary Mitchell, “Offshoring American Environmental Law: Land, Culture, and Marshall Islanders’ Struggles for Self-Determination During the 1970s,” Environmental History 22, no. 2 (April 2017): 209–234,

[37] See Joseph Masco, “‘Survival Is Your Business’: Engineering Ruins and Affect in Nuclear America,” Cultural Anthropology 23, no. 2 (May 2008): 361–398,

[38] United States Navy, “Treasure Island Naval Station Final Historical Radiological Assessment” (2006), 6-5,

[39] On the geopolitics of science during the Cold War, see Audra J. Wolfe, Freedom’s Laboratory: The Cold War Struggle for the Soul of Science (Baltimore, MD: Johns Hopkins University Press, 2018).

[40] For a related account of how weapons scientists managed “technoaesthetic” shifts in the US nuclear testing regime, see Joseph Masco, The Nuclear Borderlands: The Manhattan Project in Post-Cold War New Mexico (Princeton, NJ: Princeton University Press, 2006), 43–95.

[41] USNRDL, “History, 1946–1958,” 34.

[42] USNRDL, “History of the U.S. Naval Radiological Defense Laboratory, 1959,” 2–3.

[43] USNRDL, ”History of the U.S. Naval Radiological Defense Laboratory, 1960,” 27; USNRDL, “History of the U.S. Naval Radiological Defense Laboratory, 1962,” 14–15; USNRDL, “History of the U.S. Naval Radiological Defense Laboratory, 1963,” 11.

[44] USNRDL, “History, 1959,” 1–2.

[45] Walter W. Perkins, “HYDRA IIA – Comparison of High Explosive and Nuclear Underwater Explosions: A Summary, Analysis, and Evaluation of the HYDRA IIA Tests,” (San Diego: Naval Undersea Center, 1973).

[46] USNRDL, “History, 1959,” 3–4; USNRDL, “History, 1960,” 31–33.

[47] USNRDL, “History, 1960,” 8–9.

[48] USNRDL, “History of the U.S. Naval Radiological Defense Laboratory, 1964,” 363, 371.

[49] USNRDL, “History of the U.S. Naval Radiological Defense Laboratory, 1965,” 15.

[50] USNRDL, “History of the U.S. Naval Radiological Defense Laboratory, 1966,” 16.

[51] USNRDL, “History, 1965,” 43.

[52] USNRDL, “History of the U.S. Naval Radiological Defense Laboratory, 1968,” 3.

[53] David Perlman, “Scientists’ Drive to Save Radiation Lab,” San Francisco Chronicle, May 12, 1969.

[54] David Perlman, “Plan to Save Navy Lab,” San Francisco Chronicle, May 19, 1969.

[55] “Lawmakers Join Fight For Navy Lab,” San Francisco Chronicle, May 20, 1969; David Perlman, “HEW Looks Into Navy Lab’s Fate,” San Francisco Chronicle, June 28, 1969.

[56] United States Environmental Protection Agency, “Superfund Site: Hunters Point Naval Shipyard, San Francisco, CA,”

[57] U.S. Navy, “Hunters Point Shipyard Final Historical Radiological Assessment,” 6-30, 6-31. All ocean dumping of radioactive waste by the United States ended by 1970. Regulation of ocean dumping of radioactive waste transferred from the AEC to the EPA and NOAA after the creation of the latter agencies in the 1970s. The EPA and NOAA continue to manage and monitor the Farallon Islands waste site. On ocean dumping of radioactive waste, see Jacob Hamblin, Poison in the Well: Radioactive Waste in the Oceans at the Dawn of the Nuclear Age (New Brunswick, NJ: Rutgers University Press 2008).

[58] See National Oceanic and Atmospheric Administration (NOAA), “Greater Farallones National Marine Sanctuary,”

[59] U.S. Geological Survey, “Measurement of Seafloor Radioactivity at the Farallon Islands Radioactive Waste Dump Site, California” (Reston, VA: 2001). The estimates of the number of barrels and amount of radioactivity dumped come from a 1971 report on radioactivity in marine environments created by the National Academy of Sciences in response to a request by the AEC: Arnold Joseph et al., “Sources of Radioactivity and their Characteristics,” in Radioactivity in the Marine Environment (Washington, D.C.: National Academy of Sciences, 1971), 6-42.

[60] James Delgado, “After Crossroads: The Fate of the Atomic Bomb Target Fleet,” Journal of Maritime Archaeology 11, no. 1 (April 2016), 25-31, After Operation Crossroads, 61 target vessels were scuttled at Bikini, Kwajalein, or off the California coast. The Gasconade and Crittenden, which had also been towed to Hunters Point, were sunk off the coast of southern California in 1948. Only 9 vessels escaped scuttling and were instead sold as scrap metal.

[61] U.S. Environmental Protection Agency, “Radioactive Waste Dumping Off the Coast of California: Fact Sheet,” (Washington, D.C.: 1980).

[62] Davis, “Fallout.”

[63] Many of these surveys found elevated levels of radioisotopes in sediment samples, indicating that the barrels may be leaking radioactivity into the environment. Nevertheless, the EPA has asserted that this contamination remains localized because of the waste site’s isolation and depth, which prevent the uptake of radiation in marine food chains and other pathways to human and environmental exposure. The EPA has also claimed that radioactive decay has reduced radiation levels at the site over time, further diminishing risk levels. Some scientists and members of the public have contested these pronouncements of safety: see Lisa Davis, “Fallout,” SF Weekly, May 9, 2001,

[64] W. R. Schell and S. Sugai, “Radionuclides at the U.S. Radioactive Waste Disposal Site Near the Farallon Islands,” Health Physics 39, no. 3 (September 1980): 475-496,

[65] Thomas H. Suchanek et al., “Radionuclides in Fishes and Mussels from the Farallon Islands Nuclear Waste Dump Site, California,” Health Physics 71, no. 2 (August 1996): 167-178,

[66] The EPA conducted the first survey of the Farallon Islands waste site in 1974, finding corroded barrels but no elevated levels of radioactivity in sediment and biological samples beyond global fallout levels. In 1977, the EPA retrieved a barrel from the site that did not demonstrate any radioactivity when analyzed by scientists at Brookhaven National Laboratory.

[67] USGS, “Measurement of Seafloor Radioactivity.” Previous surveys relied on limited sampling at specific locations, which may have led to divergent findings and results.

[68] James Delgado et al., “Assessment of the Deep Sea Wreck USS Independence,” Frontiers in Marine Science 3, no. 80 (July 2016), 1–6,

[69] Researchers from the Berkeley RadWatch Project, a radiation monitoring program of the Department of Nuclear Engineering at the University of California, Berkeley, analyzed sponge samples collected during the 2015 NOAA survey of the Independence: