Uranium-235 fallout from the nuclear-powered satellite Cosmos-1402

The presence of excess uranium-235 was detected in many of the rain samples collected at Fayetteville (36°N, 94°W), Arkansas, during the period between April 1983 and March 1984. The experimental data indicate that the uranium-235 originated from the nuclear reactor on board the Soviet satellite Cosmos-1402, which fell over the South Atlantic Ocean on 7 February 1983.This investigation was supported by the National Science Foundation under Grant ATM 82-06718 and ATM 84-07618.     

Uranium fallout from the nuclear-powered satellites and volcanic eruptions

Increasing trends of the concentrations of²³⁴U,²³⁵U and²³⁸U in rain observed during the period between April 1984 and June 1985 at Fayetteville (36°N, 94°W), Arkansas, and peak concentrations of²³⁴U and²³⁵U observed in a number of rain samples collected during the months of May and June 1985 appear to be the effects of delayed fallout from the 1982 eruption of El Chichón volcano and the 1983 fall of the nuclear-powered satellite Cosmos-1402, respectively.This investigation was supported by the National Science Foundation under Grant ATM 84-07618.     

Plutonium in lungs and livers of persons from Chernobyl fallout affected areas in Byelorussia

^239+240Pu and-when possible-also the ratio²³⁸Pu/^239+240Pu was determined in the lungs and livers of 15 residents from Chernobyl-fallout contaminated areas in Byelorussia. In several cases various sections of the lungs were analyzed separately. With the exception of one person the activity concentrations of^239+240Pu, were always within the range expected from the global fallout of weapon tests in the sixties and did not indicate any contribution of Chernobyl-derived plutonium.     

Plutonium extraction from mixed aqueous media. Plutonium—Uranium separation

A systematic study is presented on Pu IV extraction with tri-n-butyl phosphate and trilaurylamine from binary mixtures of H₂SO₄ with HCl and HBr. The addition of sulfuric acid to the mentioned mineral acid solutions, was found to affect appreciably D_Pu, which recommended some useful purification procedures. The effect of water-miscible alcohols on the extraction of plutonium from HCl and HNO₃ solutions was also investigated.     

Radioactive fallout from the chernobyl nuclear reactor accident

Following the accident at the nuclear reactor at Chernobyl, in the Soviet Union on April 26, 1986, we performed a variety of measurements to determine the level of the radioactive fallout on the western United States. We used gamma-spectroscopy to analyze air filters from the areas around Lawrence Livermore National Laboratory (LLNL), California, and Barrow and Fairbanks, Alaska. Milk from California and imported vegetables were also analyzed. The levels of the various fission products detected were far below the maximum permissable concentration levels.Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.     

89,90Sr fallout from Chernobyl in the Bucharest-Magurele area

⁸⁹Sr and⁹⁰Sr were determined in the fallout of May 1986. The maximum values of 335 Bq/(m².6 h) and 110 Bq/(m².6 h) were observed on May 2 and 5. Throughout May 1986 a quantity of 860 Bq/m² of⁹⁰Sr, deposited from the fallout in the Bucharest-Mgurele area, was estimated.     

Plutonium removal from nitric acid waste streams

Separations research at the Rocky Flats Plant /RFP/ has found ways to significantly improve plutonium secondary recovery from nitric acid waste streams generated by plutonium purifications operations. Capacity and break-through studies show anion exchange with Dowex 1×4 /50–100 mesh/ to be superior for secondary recovery of plutonium. Extraction chromatography with TOPO /tri-n-octylphosphine oxide/ on XAD-4 removes the final traces of plutonium, including hydrolytic polymer.     

A Novel Metastable Pentavalent Plutonium Solid Phase on the Pathway from Aqueous Plutonium(VI) to PuO2 Nanoparticles

Here we provide evidence that the formation of PuO₂ nanoparticles from oxidized Pu^VI under alkaline conditions proceeds through the formation of an intermediate Pu^V solid phase, similar to NH₄PuO₂CO₃, which is stable over a period of several months. For the first time, state‐of‐the‐art experiments at Pu M₄ and at L₃ absorption edges combined with theoretical calculations unambiguously allow to determine the oxidation state and the local structure of this intermediate phase.     

Comparison of radionuclides levels from the Chernobyl reactor accident and from global fallout

Studies on radioactive fallout from atmospheric nuclear weapons tests have been carried out at this laboratory since the mid-fifties. The data thus generated on the levels and composition of radioactive fallout in India has been published periodically. Consequent to the Chernobyl reactor accident in the USSR in April 1986, similar studies were carried out. A number of fairly active samples were collected from commercial aircraft which had flown over the USSR soon after the accident. Even though the levels of fallout from the Chernobyl reactor accident observed in India were not significant from a health hazard view point, the studies provided detailed information on differences in the composition of fallout from the accident and long term radiation exposures likely to accrue from the Chernobyl fallout as opposed to global fallout from atmospheric nuclear weapons tests. This paper presents the results and their interpretation on the above aspects.     

Plutonium Isotopes in Sediments from the Sudanese Coast of the Red Sea

This paper presents the activity concentrations of Pu isotopes in surface marine sediments collected from the Sudanese coast of the Red Sea. The following concentration ranges were determined: ²³⁸Pu, 4.7–28.6 mBq/kg; ^239+240Pu, 53–343 mBq/kg dry weight. The average activity ratios of ²³⁸Pu/^239+240Pu (0.075±0.045 mBqk/kg) and ^239+240Pu/¹³⁷Cs (0.026±0.025 mBq/kg) are appropriately comparable to the literature values that are characteristic of the global fallout from the atmospheric nuclear weapon tests. However, ^239+240Pu/¹³⁷Cs ratio in sediments collected from the biologically rich fringing reef is an order of magnitude higher compared to other sampling locations.     

Radiation measurements and radioecological aspects of fallout from the Fukushima nuclear accident

Fallout from the Fukushima Nuclear Accident has been monitored for about 1 month in Thessaloniki, Northern Greece. Three different radionuclides, one short-lived, one relatively long-lived and one long-lived fission product were identified in air, precipitation, soil, grass and milk samples. The ¹³¹I, ¹³⁷Cs and ¹³⁴Cs activity concentrations in air reached 497, 145 and 126 μBq m⁻³, respectively on 4 April, 2011. The external exposure dose rate to humans of the order of 14.4 pSv per day due to ¹³⁷Cs deposited on the ground was very small compared to the normal background level. The accumulated dose equivalent to the adult thyroid from inhaled ¹³¹I varied from 0.4 to 3.5 nSv per day was insignificant and there was not any problem for the Greek population and no preventive measures were needed to be provided against the nuclear accident according to the Greek Atomic Energy Commission, the official agent of the Greek Government. Some special radioecological aspects in the air-grass-cow-milk-man pathway for ¹³¹I were particularly studied.     

Plutonium hydrolysis and the double double-point

There is uncertainty about the numerical value of the first hydrolysis constant of the tetravalent plutonium ion. A new method for discriminating between the claims is illustrated. It suggests the traditional estimates of that constant are closer to its true value than a singular result based on a few solvent-extraction experiments. A previously unnoticed multiple point in aqueous Pu chemistry is illustrated.     

Separation of species of radionuclides from precipitation and fallout samples

The experience with determination of species of radionuclides using the method based on in-line separation of these species by filtration and retention on columns of cation and anion exchange resins and activated charcoal, respectively, is presented. For the combined precipitation and fallout samples from the point of view of their sampling passive and indicatively active arrangements of the method have been proved. During 1984–1986 some real samples from the locality of the Institute have been analyzed, obtained results are briefly discussed and evaluated.     

Modeling the dispersion of radionuclides released during reactor accidents aboard nuclear-powered vessels

Provenance determinations of pottery by chemical analysis is reviewed and shown to work well. Since pottery is produced from a well homogenized clay paste according to a certain recipe, sharp elemental patterns are expected for a series of products having the same origin. To obtain such patterns when forming compositional groups of pottery, a consideration of experimental errors, a correction for dilution and a choice of only stable elements is necessary. The patterns thus obtained will have low probability of overlap with groups of different origin. Examples for well defined groups of German stonewares and of Mycenaean wares from the Peloponnese are recorded.     

Separation and Recovery of Uranium and Plutonium from Oxalate Supernatant

The separation of uranium and plutonium from oxalate supernatant, obtained after precipitating plutonium oxalate, containing ~10 g/l uranium and 30–100 mg/l plutonium in 3M HNO₃ and 0.10–0.18M oxalic acid solution has been carried out. In one extraction step with 30% TBP in dodecane: ~92% of uranium and ~7% of Pu is extracted. The raffinate containing the remaining U and Pu is extracted with 0.2M CMPO+1.2 M TBP in dodecane and near complete extraction of both the metal ions is achieved. The metal ions are back extracted from organic phases using suitable stripping agents. The recovery of both the metal ions separately is >99%. The uranium species extracted into the TBP phase from the HNO₃+oxalic acid medium was identified as UO₂(NO₃)₂·2TBP.     

Distribution and circulation of radionuclides originating from fallout in a forest

Water, plant and soil samples from forested area were analyzed in order to study the behavior of radionuclides in the forest ecosystem. The concentration of ¹³⁷Cs in the soil decreased with depth, while stable Cs and ⁴⁰K were almost constant. It is suggested that most of the ¹³⁷Cs once entered in the forest ecosystem is trapped in the upper part of the soil.     

Constraints on fallout melt glass formation from a near-surface nuclear test

We present major element and actinide composition data from a population of fallout glass samples produced from a single near-surface nuclear detonation. Glass major element compositions indicate that composition of local geology is a primary control on bulk fallout chemical composition. Uranium isotope compositions indicate that vaporized, residual fuel was incorporated into the melts prior to solidification, likely within seconds, and are consistent with two-component mixing between naturally-occurring uranium and residual uranium fuel. Model ages of the residual fuel in fallout are systematically inaccurate, biased towards older ages, and are consistent with two-component mixing between naturally-occurring daughter nuclides in local sediment and decay-derived daughter nuclides from residual nuclear fuel. Multiple processes such as mixing, agglomeration of melted sediment-derived droplets, and incorporation of condensates must all occur within the timescale between sediment melting and melt solidification.     

Plutonium in seawater of the Pacific Ocean

The present plutonium levels in the Pacific Ocean are summarized. The ^239,240Pu concentrations in surface seawaters in the early 2000s were in the range of 1.5 to 9.2 mBq·m⁻³ in the North Pacific and 0.8 to 4.1 mBq·m⁻³ in the South Pacific. There is no marked difference of surface ^239,240Pu distributions between the North and South Pacific subtropical gyres. The vertical profile of ^239,240Pu in the South Pacific was the similar pattern to that in the North Pacific, which is controlled by biogeochemical processes. The ^239,240Pu inventories (down to 2300 m) in the North Pacific are generally greater than that in the South Pacific, which reflects the geographical distribution of global fallout and effect of close-in fallout in the Marshall Islands.     

Plutonium isotopes in the Sea of Japan

Plutonium isotopes in the Sea of Japan were determined to assess radioactive contamination. Concentrations of ^239,240Pu in surface water of the Sea of Japan were maintained at a constant level over the past two decades in contrast to ¹³⁷Cs. A median value of surface ^239,240Pu in the Sea of Japan in this period was 5.6 mBq/m³ with the range between 2.1 and 14.0 mBq/m³, which is slightly higher than that in the western North Pacific. The vertical distribution of ^239,240Pu showed a surface minimum, a subsurface maximum and gradual decrease with increasing depth. The ²⁴¹Pu/^239,240Pu activity ratios in water columns were almost constant except for surface water. In regard to ^239,240Pu in surface water of the Sea of Japan, these findings suggest that rapid recycling of deeper plutonium occurs in the Sea of Japan due to deep convection in winter and biogeochemical processes such as particle scavenging and remineralization.