239+240Pu and 137Cs in Sediments from Tokyo Bay: Distribution and Inventory

Four sediment cores were collected from Tokyo Bay and analyzed for their ^239+240Pu and ¹³⁷Cs concentrations. Shallow nearshore sediments from Tokyo Bay have ^239+240Pu inventories which average 214±14 MBq/km². They are five times greater than the supply expected from the atmospheric global fallout at the same latitude of 42 MBq/km². The measured mean ¹³⁷Cs inventory of 433±93 MBq/km² is approximately one fifth the value expected from global fallout. Furthermore, the ^239+240Pu/¹³⁷Cs activity ratios, with a mean ratio of 0.50±0.14, are significantly greater than the ratio expected from the global fallout of 0.021. Excess ^239+240Pu inventories can be considered to have been introduced into Tokyo Bay as weathering products by soil erosion, transported via rivers and winds, and to be much more efficiently scavenged from seawater by particles resuspended at the sediment-water interface.     

239+240Pu and137Cs distributions in seawater from the Yamato Basin and the Tsushima Basin in the Japan Sea

Comparative studies between column and batch liquid emulsion membrane techniques based on HDEHP/HCl system were carried out to develop a system for isolation of²³⁴Th from natural uranium. For column investigations a spray column was constructed and used with two different modes. In the first mode the feed solution was circulated through the membrane while in the second mode the membrane phase was circulated through the feed solution. The results showed that, kinetically, the equilibrium for thorium separation using batch technique is faster than the continous column system. Quantitative permeation of thorium was achieved within one minute of mixing whereby the permeation of uranium reached equilibrium after 3 minutes with a permeation percentage less than 6%. A procedure was developed to separate²³⁴Th from natural uranium with high radiochemical purity of more than 98%.     

Simultaneous analysis of 137Cs, 90Sr, 238Pu and 239+240Pu in Brazilian seawater

Methodologies for simultaneous analysis of ¹³⁷Cs, ⁹⁰Sr, ²³⁸Pu and ^239+240Pu were developed and applied to seawater samples. ¹³⁷Cs levels in Brazilian coastal seawater ranged from 0.12 to 4.7 Bq·m^-3, for ⁹⁰Sr from 2.0 to 8.6 Bq·m^-3, for ^239+240Pu from 0.8 to 4.5 mBq·m^-3 and for ²³⁸Pu it was of 1.9 mBq·m^-3. The artificial radioactivity levels in Brazilian seawater are typical values due to fallout deposition.     

Evaluation of 239+240Pu, 137Cs and natural 210Pb fallout in agricultural upland fields in Rokkasho, Japan

The background distributions of ^239+240Pu and ¹³⁷Cs fallout in agricultural soil were investigated in Rokkasho where Japan's first commercial nuclear fuel reprocessing plant is now being constructed. The mean inventories of ^239+240Pu and ¹³⁷Cs in three fields with non-yam-cultivation history were 116 Bq·m⁻² and 3.4 kBq·m⁻², respectively. The mean atomic ratio of ²⁴⁰Pu/²³⁹Pu for all studied fields was 0.18±0.04, and was similar to that of global fallout. The ^239+240Pu concentrations correlated very well with ¹³⁷Cs (r = 0.97) in spite of heavy disturbance of the soil, and the activity ratio of ^239+240Pu/¹³⁷Cs was 0.037±0.007, which is a typical value for global fallout. These results showed that the nuclides had similar behavior in agricultural upland fields in Rokkasho. Since ²¹⁰Pb is steadily deposited from the atmosphere to the land, this nuclide could be an index for the degree of disturbance of a field and of soil lost from the field. The ratio of excess ²¹⁰Pb inventory in the soil to the equivalent inventory of atmospheric ²¹⁰Pb deposition was 96%, and indicated that soil was not lost from the cultivated fields. This revised version was published online in July 2006 with corrections to the Cover Date.     

Radionuclide ratios of90Sr/137Cs and239(240)Pu/137Cs in contaminated surface air after the Chernobyl accident in Asutria

Energy straggling in pulse height distributions of plastic scintillation counters of 4 and 10 cm in thickness was measured for 1 GeV/c pions and studied by Monte Carlo simulations. Calculated energy loss distributions are in good agreement with the experimental data and also with the prediction by the Landau straggling function.     

238Pu, 239+240Pu, 241Am, 90Sr and 137Cs in mountain soil samples from the Tatra National Park (Poland)

Activity concentrations and inventory for ²³⁸Pu, ^239+240Pu, ²⁴¹Am, ⁹⁰Sr, and ¹³⁷Cs in soil from Tatra Mountains of Poland are presented. Soil samples were collected using 10 cm diameter cores down to 10 cm and sliced into 3 slices. Details of the applied procedure are described with the quality assurance program. The maximum activity concentrations found for various samples were: 1782±13 Bq/kg, 17.4±0.9 Bq/kg, 3.4±0.3 Bq/kg and 84±7 Bq/kg for ¹³⁷Cs, ^239+240Pu, ²⁴¹Am and ⁹⁰Sr, respectively. The maximum cumulated deposition of ^239+240Pu is 201±8 Bq/m². The origin of radionuclides is discussed, based mostly on the observed isotopic ratio of Pu. Significant correlations were found between ^239+240Pu, ²⁴¹Am and ¹³⁷Cs. The effective vertical migration rate seems to be in the order of: ⁹⁰Sr≫Pu>Am>Cs.     

Vertical Profiles, Inventories, and Activity Ratios of 239+240Pu and 137Cs in Sediments from Sagami Bay, Western Northwest Pacific Margin

Marine sediment cores were taken from Sagami Bay of the western Northwest Pacific and analyzed for ^239+240Pu and ¹³⁷Cs activities. A significant correlation was observed between ^239+240Pu and ¹³⁷Cs activities in sediment cores, i.e., their vertical profiles. The measured activities which were used to obtain the inventories of ^239+240Pu and ¹³⁷Cs in the sediment column, showed large variations, ranging from 36 to 474 MBq/km² for ^239+240Pu and 49 to 652 MBq/km² for ¹³⁷Cs. ^239+240Pu inventories in the sediment from one region in the Bay, Sagami Nada were 5–10 times greater than those predicted from atmospheric global fallout 42 MBq/km² at the same latitude. On the other hand, ¹³⁷Cs inventories, with a mean value of 297±168 MBq/km², were much less than predicted, 2040 MBq/km². The activity ratios of ^239+240Pu/¹³⁷Cs obtained, with a mean of 0.65±0.17, were significantly greater than the ratio predicted from fallout, 0.021. Furthermore, there was a clear relationship between both ^239+240Pu and ¹³⁷Cs inventories and the water content, indicating that higher inventories may be attributed principally to concentration in, and scavenging by, fine-grained particles.     

Inventories of 239+240Pu, 137Cs, and excess 210Pb in sediment cores from brackish Lake Obuchi, Rokkasho Village, Japan

The aim of this study was to measure the distribution and inventories of ^239+240Pu, ¹³⁷Cs, and excess ²¹⁰Pb (²¹⁰Pb_excess) in sediment core samples from brackish Lake Obuchi, which is in the vicinity of nuclear fuel facilities in Rokkasho Village, Japan. The inventory of the ^239+240Pu activity in the sediment samples from the estuary of a freshwater river, the central point of the lake, and the deepest point in the lake were 0.18, 0.29, and 0.24 kBq·m^–2, respectively. The inventories of ¹³⁷Cs and ²¹⁰Pb_excess in sediments were 0.83–1.2 kBq·m^–2 and 25–30 kBq·m^–2, respectively. The mean ^239+240Pu/¹³⁷Cs and ²¹⁰Pb_excess/¹³⁷Cs activity ratios were 0.23 and 28, respectively. The^239+240Pu/¹³⁷Cs activity ratios were approximately 13–24 times the ratio expected from global fallout. The inventories of ^239+240Pu and ²¹⁰Pb in sediments were higher than the inventory expected from atmospheric fallout, but the ¹³⁷Cs inventory was significantly lower than expected.This revised version was published online in November 2005 with corrections to the Cover Date.     

239Pu, 240Pu, 241Pu, 241Am, 137Cs,and 210Pb in seafloor sediments in the western North Pacific Ocean and the Sea of Japan: distributions,sources and budgets

Journal of Radioanalytical and Nuclear Chemistry - Vertical distributions of 239Pu, 240Pu, 241Pu, 241Am, 137Cs, and 210Pb concentrations, and 240Pu/239Pu ratios were determined in seafloor...     

239+240Pu concentrations of sediments and seawater in the coastal sea of Korea

Summary The ^239+240Pu content of the marine sediments and seawater of the costal sea of Korea was measured. In marine sediments the ^239+240Pu concentrations were in the range of 0.11-1.91 Bq/kg dry weight and in the coastal sea of Korea the ratio of ^239+240Pu/¹³⁷Cs was 0.27. The correlations between ^239+240Pu and ¹³⁷Cs concentrations and the content of organic matter (C, O, H, N, S) as well as the grain size of marine sediment were investigated by regression analysis. The distribution coefficient of ^239+240Pu was 1.22^. 10⁵. The ^239+240Pu concentration in seawater increased with seawater depth. However, the ¹³⁷Cs concentration in seawater did not change considerably with depth.     

90Sr, 137Cs, 238Pu, 239+240Pu and 241Am levels in terrestrial and marine ecosystems around the Italian base in Antarctica

During the last 14 years the Radioecology Laboratory of Parma University and the General Chemistry Institute of Urbino University collaborated on a radioecological programme having the aim to observe the evolution of antropogenic radioactivity in Antarctica in the period 1987-2001. The artificial radionuclides considered were ⁹⁰Sr, ¹³⁷Cs, ^239+240Pu,²³⁸Pu and ²⁴¹Am. The contamination seems to be higher in the continental environment rather than in the marine one. Mosses, algae and lichens showed the highest values for all radionuclides analyzed. The results prove that the Antarctic continent is interested by radioactive pollution. As far as ¹³⁷Cs is concerned, a progressive decrease was observed.     

240Pu/239Pu atom ratios in the bottom sediments of the NW Pacific Ocean

^239+240Pu concentrations and ²⁴⁰Pu/²³⁹Pu atom ratios in bottom sediments of the Yellow Sea, Korea Strait, East Sea (Sea of Japan), Sea of Okhotsk, and Northwest Pacific Ocean were determined. In coastal sediments near the Korean Peninsula, ^239+240Pu concentrations varied from 0.02 to 1.72 Bq^.kg^-1, and their ²⁴⁰Pu/²³⁹Pu atom ratios from 0.15 to 0.24, with an average of 0.20±0.03. ²⁴⁰Pu/²³⁹Pu atom ratios of bottom sediments in the deep NW Pacific Ocean and its marginal seas (East, Okhotsk seas) were in the range of 0.15-0.23. A little elevated ²⁴⁰Pu/²³⁹Pu atom ratios in the bottom layer sediment may be due to Pu released into the environment during the pre-moratorium period, having high ²⁴⁰Pu/²³⁹Pu atom ratios and low ²³⁸Pu/^239+240Pu activity ratios.     

Studies of the vertical distribution of134Cs,137Cs,238Pu,239, 240Pu,241Pu,241Am and210Pb in ombrogenous mires at mid-latitudes

Six peat cores taken from three unmodified blanket and raised bogs in Ireland were sectioned and analyzed for a range of radionuclides including¹³⁴Cs,¹³⁷Cs,²³⁸Pu,²³⁹Pu,²⁴¹Am, and²¹⁰Pb.¹³⁴Cs and¹³⁷Cs were measured by high resolution gamma-spectrometry, while the transuranium nuclides were determined after chemical separation by alpha-spectrometry.²⁴¹Pu, present on the electroplated discs together with Pu(), was measured directly by low-level liquid scintillation counting. Core chronologies were established by measuring the unsupported²¹⁰Pb component using low energy photon spectrometry (LEPS). From the resulting profiles, relaxation depths and migration rates for the above mentioned radionuclides have been determined and differences in the values of these parameters interpreted.²³⁸Pu/^239,240Pu and²⁴¹Pu/^239,240Pu ratios have been examined carefully and are discussed in some detail. Finally, the contribution from Chernobyl to the total radiocaesium inventory in each core has been established using the¹³⁴Cs/¹³⁷Cs ratio observed in the initial fallout from Chernobyl.     

Determination of 238Pu, 239+240Pu and 241Am in air filters

The aim of this work is to present the method for sequential plutonium and americium activity determination in air filters using chromatographic radionuclide separation and alpha spectrometry measurement. The developed method may be employed for the purposes of workplace monitoring and as an indicator of the need of introducing the individual monitoring as well as a useful complementation of individual monitoring. Basic parameters describing the developed method such as values of chemical recoveries and minimum detectable activities for plutonium and americium isotopes have been determined. Applied counting efficiency was obtained using Monte Carlo calculation method.

     

Fallout 137Cs, 90Sr and 239+240Pu in soils polluted by heavy metals: Vertical distribution, residence half-times, and external gamma-dose rates

The industrial pollution of an ecosystem, e.g., by heavy metals, might also affect the behavior of fallout radionuclides in the soils of these areas. To study such effects, we determined at various distances from the huge copper-nickel smelters at Monchegorsk on the Kola Peninsula (Russia) and at a reference site: (1) the vertical distribution of fallout ¹³⁷Cs,⁹⁰Sr and^239+240Pu in the soil, (2) the corresponding residence half-times in different soil horizons, and (3) the resulting external gamma-dose rates at these sites in 1 m height due to ¹³⁷Cs in the soil. The data show that the residence half-times and the partitioning of the fallout radionuclides among the various soil horizons depend significantly on the extent of the heavy metal pollution at the sites. The resulting external gamma-dose rate in 1 m height due to ¹³⁷Cs in the soil is, however, rather similar at the various sites.     

Interlaboratory comparison of actinides in human tissue239Pu and240Pu

An international laboratory intercomparison of actinides in human tissues was organized by the United States Transuranium Registry and the National Institute of Standards and Technology. Five laboratories from the United States, United Kingdom, and Japan participated in the intercomparison. The laboratories were requested to analyze Standard Reference Materials 4351 (Human Lung) and 4352 (Human Liver) for²³⁹Pu and²⁴⁰Pu concentration. Approximately equivalent measurement capabilities were generally found among the participants. The results of this intercomparison were statistically comparable to those used for the original certification of the SRM's and were combined for a re-evaluation of the certified values. The combined data sets provide a better characterization of the inhomogeneity of these reference materials and result in a better basis for certification.Deceased.     

Radioanalytical approach to determine 238Pu, 239+240Pu, 241Pu and 241Am in soils

The simultaneous determination of multiple actinide isotopes in samples where total quantity is limited can sometimes present a unique challenge for radioanalytical chemists. In this study, re-determination of ²³⁸Pu, ^239+240Pu, and ²⁴¹Am for soils collected and analyzed approximately three decades ago was the goal, along with direct determination of ²⁴¹Pu. The soils had been collected in the early 1970’s from a shallow land burial site for radioactive wastes called the Subsurface Disposal Area (SDA) at the Idaho National Lab (INL), analyzed for ²³⁸Pu, ^239+240Pu, and ²⁴¹Am, and any remaining soils after analysis had been archived and stored. We designed an approach to reanalyze the ²³⁸Pu, ^239+240Pu, and ²⁴¹Am and determine for the first time ²⁴¹Pu using a combination of traditional and new radioanalytical methodologies. The methods used are described, along with estimates of the limits of detection for gamma-and alpha-spectrometry, and liquid scintillation counting. Comparison of our results to the earlier work documents the ingrowth of ²⁴¹Am from ²⁴¹Pu, and demonstrates that the total amount of ²⁴¹Am activity in these soil samples is greater than would be expected due to ingrowth from ²⁴¹Pu decay.     

Temporal variations of137Cs concentrations in the surface seawater and marine organisms collected from the Japanese coast during the 1980's

The surface seawater and marine organisms were collected on the Japanese coast and analyzed for their¹³⁷Cs concentrations during the 1980's. The¹³⁷Cs concentrations in surface seawater decreased almost exponentially with time and the¹³⁷Cs removal rate constant was estimated to be 0.0445 y⁻¹. The¹³⁷Cs concentrations in marine organisms also decreased almost exponentially with time. The environmental half-lives of¹³⁷Cs in muscle and viscera of fish, crustacea, and seaweed were estimated from the measured decreases of¹³⁷Cs concentrations.     

Vertical profiles of 239+240Pu in seawater from the East China Sea

Seawater samples were collected from the East China Sea continental shelf and analyzed for ^239+240Pu activities. The vertical profiles of ^239+240Pu had a similarity for all three stations in the East China Sea. ^239+240Pu concentrations were low in the surface layer (3-4 mBq/m³) and increased gradually with depth to become high in the near-bottom layer (7-10 mBq/m³). ^239+240Pu concentrations in seawater and the concentrations of suspended particles showed almost the same vertical profiles in the East China Sea continental shelf. The maximum value of ^239+240Pu found in the near-bottom layer may be due to the contribution of Pu-rich suspended particles.