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The 141st meeting of the Advisory Committee for Biology and Medicine was held January 7-8, 1972, at AEC Headquarters and the “H” St. Office. John B. Storer (Scientific Secretary), and Miss Rosemary Elmo (Executive Secretary). Dr. Clarence Larson was present representing the Commission. A very large number of Headquarters personnel from the Division of Biology and Medicine and also from other Divisions, as well as representatives from other agencies, were also in attendance. (Dr. Richard Fred, Bureau of Radiological Health, PHS; Dr. Neal Nelson, Radiological Toxicological Branch, EPA; Dr. Charles Liddle, EPA; Dr. Wayne Hanson, Technology Assessment Division, EPA) . Dr. Moseley called the meeting to order and asked Dr. Totter for any Anderson, Sanders, Watters, and Marks, and Mr. Kondulis.) He then asked Dr. Larson if he had any comments. Dr. Larson indicated an intense interest on the part of the Commission in the biological effects of plutonium, especially in view of the anticipated large number of fast breeder reactors. Dr. Totter introduced the scientific program which had been organized by Dr. William Bair. The initial portion of the program was presented by representatives from divisions other than DBM. Following this, DBM representatives summarized the current status of its studies on plutonium The first presentation was by Dr. McVey from the Division of Reactor Development. His presentation was concerned with the future requirements of plutonium as a reactor fuel. By going to fast breeder reactors it will be possible to use about 807. of the naturally occurring uranium in the world. The fast breeders will utilize depleted uranium as a source of energy and it is expected that the breeding ratio will be 1.27. By the year 2000 it is expected that the total inventory of plutonium-239, principally in reactors, will be between 1000 and 2000 metric tons. Even by 1980, there will be about 50 tons of plutonium inventory in power reactors in the United States. Even at the present time and increasingly so in the future, waste disposal and the decommissioning of facilities is concerned mainly with the hazard from plutonium rather than from fission products. In, the light water reactors there is an appreciable amount of energy released from the fission of plutonium. The Division of Reactor Development and Technology is now focusing its effort on the liquid metal fast breeder reactors. Dr. McVey considered potential sources of release of plutonium. The first of these is in the fabrication of reactor components (fuel elements). This work is now done in glove boxes but the hope is that it will be possible to go increasingly to automation. He went into a general
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discussion of how much plutonlum waste is generated and how it can be reclaimed or di.sposeci of. He also poin~ed out that ~n zddition to the hazard from inhalation or ingestion of pl!itonium, there is an associated penetrating radiation from large qtiantities of plutonium. The amount of x- and gamma-rays released increases with time as impurities such as ammicium grow in. There is also some associated neutron exposure. A second possible point of exposure or release of plutonium is in fuel reprocessing, Here agai~, the principal hazard in the reprocessing of fuel elements is plutonlum rather than the fission products. The Oak Ridge National Laboratory has undertaken & study of how a “zero release” reprocessing plant might operate. A third possibl~ source of release IS in the shippl.ng of materials containing plutonium The research in ~his area is concerned with how plutonium might be shipped In a form that is not respirable. The fourth and fifth possible sources of release are in the decommissioning of obsolete facilities and in the refuellng of reactors. Following Dr. Mc\ley’s presentation, Dr. Stoiic raised the question of cost per kilowatt hour from reactors. He pointed out that the projected costs now are very much higher than were estimated a few years ago. Dr, Larson responded, pointing out that the Increase in cost is largely because of a tripling of construction costs and an increased interest on money that is borrowed to finance construction. Mr. George Pleat., from the Division of Production and Materials Management, described some of the activities of his Division with respect to plutonium-238 and plutonium-239. The anticipated requirement for plutonium-238 by 1980 will be about 450 kilograms. Medical requirements for plutonium-238 which are now very small may increase significantly. With respect to prod~]ction of plutonium-239, there were 6500 kilograms of non-weapons grade plutonium available as of last summer. This material is suitable for reactors but no~ for weapons. Future production of plutonium-239 will depend principally on the Savannah River Plant, which has three reactors. Weapons grade plutonium will come from this facility for the next ten years. The N reactor at Richland, Washington, will be operated until 1974, Production there is for reactor grade plutonium. The materials managemen~ program was initiated because the storage problem, particularly that associated with scrap materials, became serious. At the present time, ~here are about 500 kilograms of plutonium-239 associated with various scrap materials. The people in Materials Management are trying to reduce this inventory and to reduce the rate of production of new scrap. At present, about 300 kilograms a year of plutonium In scrap material is being generated,
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Mr. G. Dix, of the Division of Space Nuclear Systems, discussed past and projected requirements for nuclear devices in connection with the space program. To date, 324,000 curies of plutonium-238 have been launched in connection with the space program. Three of the thirteen devices containing plutonium-238 were aborted. About 100,000 curies of plutonium-238 was involved in these aborted missions. It is expected that in 1972 approximately 200,000 curies will be launched. The Division of Biology and Medicine is actively involved in the safety evaluation of each device. There is an additional interface in that the aerial radiological monitoring survey systev. developed by the Civil Effects Branch under Mr. Joe Deal is available to assist in the recovery of sources from aborted missions. At present there are four plutonium-238 packages on the moon and three of these are operating at a capacity of 70 watts. Mr. Dix then discussed projected launches and the requirements for plutonium-238. He reviewed the conceptual design of future spacecraft. The design for the SNAP devices is now for containment of the radioactivity rather than for burn-up in the atmosphere. He closed by emphasizing the cooperation with DBM and their dependency on DBM for help with safety problems. Mr. Robert Catlin, of the Division of Operational 5afety, discussed problem areas with respect to plutonium from the point of view of his Division. The first area concerned the question of radiation standards with respect to plutonium. With the abolishment of the Federal Radiation Council, there is presently no interface between the AEC and other agencies. The Environmental Protection Agency has the responsibility for standards but it will be some time, apparently, before guidance is provided by EPA. He identified two areas specifically that make it difficult to establish standards. One is that the rate and extent of translocation of plutonium in the body is poorly understood. The second is that the environmental pathways by which plutonium can reach human beings are poorly defined. Another difficult area for the Division of Operational Safety concerns the question of cleaning up and releasing to the public previously contaminated areas. Such areas are typified by the Bikini Atoll, the area ar~und the Rocky Flats plant and the Nevada test site. He pointed out that at present there is a lack of emergency guidelines which specify action levels for certain.. levels of plutonium contamination. In the medical area there is presently an insufficiently sensitive method for detection of plutonium body burdens in the human body. Improved methods of therapy for removal of plutonium would also be very helpful. A final point which he considered a problem area was the question of public acceptance of plutonium as a fuel for energy generation in the future. Dr. Moseley asked whether the National Council on Radiation Protection is preparing a report on plutonium. Mr. Catlin thought that they were. Dr. Haagen-Smit asked about EPA’s relation to the Division of Operational
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Safety. Mr. Catlin pointed out that EPA took over the Federal Radiation Council’s function and they are charged with providing guidance with respect to radiation problems. The mechanism for discussions between agencies which was provided by the FRC no longer exists . As an interim procedure the AEC may necessarily have to set some of its own guidelines since the reorganization setting up EPA has caused a serious delay in providing this information. Dr. Stout asked about the problem of determining degree of exposure to plutonium and asked whether there might be exposures that we simply don’t know about. Mr. Catlin thought there might be such exposures but that it would be relatively unlikely. Detection methods are not sensitive enough to detect very low levels of exposure. He pointed out that if plutonium facilities are not controlled by the AEC and if they continue to proliferate, the problem of plutonium exposure could become acute. Dr. Stout asked where the necessary instrumentation for detection of low levels would come from. Dr. Totter felt that tl~e Division of Biology and Medicine’s instrument development program wol]ld probably be able to meet the requirement. Mr. Facer, from the Division of Military Application, discussed the problem of plutonium ctmtamination of soil. Among the areas where such contamination has occurred are Palomares in Spain, Thule, Greenland, the Nevada Test Site, the test sites in the Pacific, and the Rocky Flats operation in Colorado. Accidents, weapons tests, etc., have all contributed to spreading plutonium around. Mr. Facer felt strongly that the criteria for cleaning up an area are far too conservative in view of the biomedical evidence concerning the likelihood of a significant exposure from resuspension of plutonium from the soil or through movement up the ecosystem. In Spain they removed 5500 drums of soil where the contamination was relatively high and deep-ploughed a sq[lare mile area where any level of plutonium was Dr. Bair then introduced the biomedical portion of the briefing. The first speaker was Dr. Engelmann, who described current studies on the resuspension of radioactive materials from the ground surface. Various contractors have undertaken systematic studies of the factors involved in resuspension. Earlier attempts to estimate a single constant which represented a resuspension factor” proved not to be very helpful. One current approach that is being used is the direct one of “salting” an area with a contaminant and “ making direct measurements of how it moves down wind. These studies are being conducted at Rocky Flats. Dr. Engelmann pointed out that,plutonium may quickly gets attached to larger particles which puts many of the particles beyond the respirable range. At present, they estimate that 20-40% of the plutonium contamination at Rocky Flats is in the respirable range. Dr. Engelmann closed by outlining additional ongoing and proposed research being monitored by his branch of DBM. Mr. Jared Davis, formerly of the DBM staff, and now with the Nevada Operations Office, described the studies on plutonium contamination by alpha
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emitters unless the levels were very high, At present there are 250 square miles of the Nevada Test Site contaminated with “significant” amounts of plutonium. An applied ecology group has been formed at the test site which is supported both by the Division of Biology and Medicine and the Division of Military Application. In addition, there are representatives from a number of other agencies on the steering committee. The steering committee provides guidance on priorities of research activities. An ad hoc committee on plutonium has been [established to recommend research approaches to the plutonium problem. The plutonium problem is considered to have a high priority. Studies by this group are confined to the Nevada Test Site. The Environmental Protection Agency is looking at areas outside the boundaries of the test site. The work to date indicates that plutonium contamination is 3-7 times higher under the brush that grows on the desert floor than it is on the desert floor. The old surveys, were made between the stands of brush and therefore underestimated the extent of contamination. Mr. Davis described in some detail some of the proposed work which involves many organizations and many disciplines. Basically they will be looking at the distribution over the surface of selected areas of the test site, the distribution with soil depth, the amounts in the native animals and in the plants growing in thes{’ regions. Dr. Vaughan, from the Battelle Northwest Ecology group, discussed “reentrainment” of plutonium in ecosystems through biological factors. He suspects that chelation plays an important role in the reentrainment phenomenon. They have found that plants growing around fuel processing installations show a higher level of plutonium than they would have expected. Because of the strong discrimination against plutonium when it is ingested, he suggested that the body burdens found in animals in contaminated areas may result from respiration of the material rather than its ingestion. Dr. Lindenbaum, from the Argonne National Laboratory, discussed his experiments in small animals using plutonium and americium. The materials were given by injection rather than by the respiratory route and the measurements made were concerned primarily with distribution and excretion of these nuclides . He tried various proportions of colloidal plutonium in the injected solutions and found that the greater the percentage of colloid, the higher the retention in the liver as opposed to bone. Later, however, the material deposited in the liver moves to the bond endosteum. Like many investigators before him, he found that chelating agents are usefuly in removing either of these materials from the liver. The loss in the chelated form is through the biliary system. He is of the opinion that 20 nanograms of plutonium per gram of liver is a threshold for killing of the liver cells which then enables translocation to bone. Chelation is not useful in removing radionuclides from bone. He indicated that they plan to extend their studies to dogs. They also plan to try to utilize “glucan” to remove endothelial system. If chelation is used apparently there is significant excretion Dr. W. Jee, from the University of dogs that has been conducted there. This radionuclides from the reticuloin conjunction with glucan, then through the urinary tract. Utah, described the research in was the first laboratory established
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by DBM to study the long term toxic effects of plutonium relative to radium utilizing beagle dogs as the experimental animal. In their original experimental design, they injected six groups of dogs with plutonium at doses ranging from .016 to 2.88 microcuriesJkg body weight. An additional control group was included. At present all but one of the dogs is dead. Osteosarcumas were found in all the treated groups and no osteosarcomas were found in controls. They later set up a second phase of the study in which the radiation doses went down from .015 to .00064 microcuries/kg. None of these animals has yet died and none has yet shown an osteogenic sarcoma but …
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