Past Nuclear Weapons Tests

Am-241 is a manmade metal that is produced from plutonium. Am-241 found in the environment is the result of past nuclear weapons testing. 

Exposure of the general population to 241 Am via air, water, soil, and food are generally very low these background levels are a result of fallout from past atmospheric nuclear weapons tests. Since 1973, 241Am air concentrations have been less than 1 aCi/m3 (0.037 pBq/m3) and are continuing to decline (Bennett 1979). Levels around nuclear power plants are indistinguishable from fallout background (EPRI 1981). 

We have attempted to follow Urey s suggestion and maintained two research projects side by side in our laboratories during the past decade (a) studies on the debris from the nuclear weapons tests, and (b) studies on the origin of the earth and the solar system. 

From the 137Cs profile of the core (Fig. 3 A), three time markers can be derived The beginning of the nuclear weapon tests (1952) in the depth interval from 92-96 cm, the culmination of the nuclear weapon tests (1963-64) in the depth interval from 52-56 cm and the Tschemobyl reactor accident (1986) in the top four cm. This implies, however, that the last 16 years are missing in the core. This may be due to either partial erosion of the sediment or infrequent occurrence or absence of flooding events during the past decade. From the three time markers a mean sedimentation... 

Before natural tritium could be fully exploited for studies of natural water systems, tritium from anthropogenic sources (mainly nuclear weapon tests) was added to the atmosphere in considerable amounts. By the mid 1960s the natural background of tritium in precipitation was practically masked by so-called bomb tritium (e.g., Weiss et al. 1979 Fig. 1). For the past 4 to 5 decades, bomb tritium severely limited the use of natural tritium as a tracer because only few uncontaminated tritium data are available from the pre-bomb era. However, bomb tritium offered a new tool for studies of water movement in natural system. It is equivalent to a dye that was introduced into the environment on a global scale at a relatively well-known rate. Most of the bomb tritium was added to the environment in three pulses during 1954, 1958-1959 and, predominantly, 1963. 

In conclusion, such relatively short-term studies only hint at the likely scale of effects possible following such incidents if fast, remediative action is not taken, and harmful levels of are transported through the atmosphere prior to deposition back on the land and incorporation into the food chain. No further major reactor accidents have taken place since Chernobyl, and nuclear weapon tests are much less common than 40—50 years ago. However, in the fight of the current build-up of such weapons in places such as North Korea, Pakistan, and the Middle East, and serious consideration, at least in the UK, of recommencing a program of nuclear reactor construction as a means of combating reliance on fossil fuel burning, lessons from the recent past must be kept in mind. 

In the past, radioanalytical chemistry laboratories processed samples resulting from monitoring nuclear weapons development facilities, fallout from nuclear weapon tests in the atmosphere, and nuclear power stations. At present, monitoring cleanup of former nuclear facilities is a major source of samples, and efforts are... 

Finally, a study is underway to determine the suitability of the Nevada Test Site in southern Nevada which has been used in the past for both surface and underground testing of nuclear weapons, to see if it may possibly be suitable as a potential permanent radioactive waste repository site. 

The primary source of radionuclides produced in the fission process and found in the environment is atmospheric testing of nuclear weapons. The public has been exposed to these and other radionuclides for five decades, but there has been a substantial decline in atmospheric testing in the past two decades. Therefore the major source of fission product radionuclides in recent years has been from nuclear accidents. A nuclear reactor meltdown could release a spectrum of radionuclides similar to that of a nuclear bomb explosion, but the ratios of nuclides would greatly differ for the two cases. The reason for the differences in ratios of radionuclides is that during the reactor operation the long-lived radionuclides tend to build up progressively, whereas the... 

As part of the biogeochemical cycle, the injection of iodine-containing gases into the atmosphere, and their subsequent chemical transformation therein, play a crucial role in environmental and health aspects associated with iodine - most importandy, in determining the quantity of the element available to the mammalian diet. This chapter focuses on these processes and the variety of gas- and aerosol-phase species that constitute the terrestrial iodine cycle, through discussion of the origin and measurement of atmospheric iodine in its various forms ( Sources and Measurements of Atmospheric Iodine ), the principal photo-chemical pathways in the gas phase ( Photolysis and Gas-Phase Iodine Chemistry ), and the role of aerosol uptake and chemistry and new particle production ( Aerosol Chemistry and Particle Formation ). Potential health and environmental issues related to atmospheric iodine are also reviewed ( Health and Environment Impacts ), along with discussion of the consequences of the release of radioactive iodine (1-131) into the air from nuclear reactor accidents and weapons tests that have occurred over the past half-century or so ( Radioactive Iodine Atmospheric Sources and Consequences ). 

Radioactive iodine can be inlialed as a gas or ingested in food or water. It dissolves in water so it moves easily from the atmosphere into humans and other living organisms. People are exposed to 1-129 from the past testing of nuclear weapons, and 1-131 from nuclear power plant emission.. ... 

On Sept. 19, 1958 there was published in Science a paper by Dr. Miriam P. Finkel of Argonne National Laboratory in which she communicated her observations on the effects of strontium-90 injected into mice on life expectancy and on incidence of tumors of bone and blood-forming tissues. She discussed the question of whether or not the effects are proportional to the amount of injected strontium-90 at low doses, and reached the conclusion that it is likely that there is a threshold with value for man between 5 and 15 /ic. (as compared with the present average value from fallout, about 0.0002 y-o,., and the predicted steady-state value from fallout for testing of nuclear weapons at the average rate for the past five years, about 0.02 yc.). Her paper ends with the sentence In any case, the present contamination with strontium-90 from fallout is so very much lower than any of these levels that it is extr nely unlikely to induce even one bone tumor or one case of leukemia. ... 

Since the advent of nuclear weapons hundreds of tons of man-made Pu have accumulated. Large amounts of fission products and heavy radionuclides have been released to the environment from nuclear weapons production, testing, and recovery, from nuclear fuel fabrication and reprocessing of spent nuclear fuel, or from past poor disposal and interim storage practices. About 6.4 billion m of contami-naled soil and groundwater are estimated to exist within the U.S. Department of En-ci gy complex (U.S. Department of Energy, 1998). Testing of nuclear weapons released approximately 3.5 t of Pu into the atmosphere and 95 kg of Am built up... 

The production of nuclear weq)ons in the United States has required a vast array of facilities, including mines, laboratories, nuclear reactors, chemical plants, machine shops, and test sites. Our weapons production conq)lex has manufactured tens of thousands of warheads over the past 50 years, resulting in radioactive contamination in thousands of buildings, soils, surface water and groundwater. The production complex, including sites in 33 of our states and Puerto Rico, totals 10.8 million square meters of buildings and 9,360 square kilometers of land (or 936,000 hectares)- a total area about one-third the size of Belgium. 

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