Distribution and dynamics of radionuclides and stable elements in the coastal waters off Rokkasho Village, Japan, prior to the opening of a nuclear reprocessing facility

The suspended particles floating in the seawater have the ability to biologically, as well as physically adsorb radionuclides and other elements dissolved in seawater. We have studied the distribution and composition of suspended particles, as well as the state of eluted of radionuclides in the decomposition process, in the coastal waters off Rokkasho Village, where radionuclides will be discharged from a nuclear fuel reprocessing plant in the near future.     

Distribution and dynamics of radionuclides and stable elements in the coastal waters off Rokkasho Village, Japan, prior to the opening of a nuclear reprocessing facility

A survey was conducted to determine the concentration levels of ³H, ¹³⁷Cs, ⁹⁰Sr, ^238,239+240Pu, and ^234,235,238U in seawater off Rokkasho Village, Japan, before the start-up of a nuclear-fuel reprocessing plant. The level, fluctuation range and distribution characteristics of each radionuclide was determined     

Vertical distribution of uranium concentrations and 235U/238U atom ratios in the coastal water off Aomori, Japan: A survey prior to the operation of a nuclear fuel reprocessing facility

Summary From the viewpoint of environmental radioactivity monitoring, the determination of uranium and its isotope ratio is important for identifying and assessing the environmental impact of any unexpected release from nuclear facilities. In this work, a survey was conducted to determine ²³⁸U concentrations and ²³⁵U/²³⁸U atom ratios in coastal waters off Rokkasho Village, Aomori, Japan, where several uranium-related nuclear facilities have been operating since 1992, and a newly constructed nuclear fuel reprocessing plant is scheduled to be commissioned in 2006. Seawater samples were analyzed directly after a 10-fold dilution using isotope dilution sector-field ICP-MS. Based on the results, we concluded that there is no observable uranium contamination in the investigated sites. In addition, for the first time, a correlation between uranium concentration and salinity was established in coastal waters using the SF-ICP-MS technique.     

An anion exchange technique for separation of Na and K for neutron activation analysis of W-Ti alloy

Anthropogenic radioactivity is being measured in near-real time by an international monitoring system designed to verify the Comprehensive Nuclear Test Ban Treaty. Airborne radioactivity measurements are conducted in-situ by stations that are linked to a central data processing and analysis facility. Aerosols are separated by high-volume air sampling with high-efficiency particulate filters. Radio-xenon is separated from other gases through cryogenic methods. Gamma-spectrometry is performed by high purity germanium detectors and the raw spectral data is immediately transmitted to the central facility via Internet, satellite, or modem. These highly sensitive sensors, combined with the automated data processing at the central facility, result in a system capable of measuring environmental radioactivity on the microbeequerel scale where the data is available to scientists within minutes of the field measurement. During the past year, anthropogenic radioactivity has been measured at approximately half of the stations in the current network. Sources of these measured radionuclides include nuclear power plant emissions, Chernobyl resuspension, and isotope production facilities. The ability to thoroughly characterize site-specific radionuclides, which contribute to the radioactivity of the ambient environment, will be necessary to reduce the number of false positive events. This is especially true of anthropogenic radionuclides that could lead to ambiguous analysis.     

Temporal and spatial variations of <Superscript>137</Superscript>Cs in the waters off a nuclear fuel reprocessing facility in Rokkasho,Aomori, Japan

Five survey cruises were carried out from 2004 to 2007 to determine ¹³⁷Cs concentrations in the water columns off Rokkasho Village, Aomori Prefecture, Japan, where the spent nuclear fuel reprocessing plant of Japan Nuclear Fuel Ltd has been undergoing test operation since March 2006. Seawater samples were collected with a large volume in situ filtration and concentration system at different depths in the water column. ¹³⁷Cs in particulate form could not be detected in the survey area. Dissolved ¹³⁷Cs showed temporal variation, especially in the surface water. Based on the results, it was concluded that no observable ¹³⁷Cs contamination was present in the investigated area. The distribution of ¹³⁷Cs concentrations was influenced by the mixing between the Tsugaru and Oyashio Currents.     

Mechanism of 7Be scavenging from the atmosphere through precipitation in relation to seasonal variations in Rokkasho Village, Aomori Prefecture, Japan

⁷Be deposition fluxes and atmospheric concentrations were measured at Rokkasho Village, Aomori Prefecture, Japan, from 2000 to 2005. It was confirmed that the ⁷Be deposition fluxes were minimum in summer, and the fallout maximizes in winter. The atmospheric concentration of ⁷Be was especially low in summer, and high in the other three seasons. A positive correlation was observed between the amount of precipitation and ⁷Be deposition. Clear seasonal differences were evident among the ratios of ⁷Be deposition flux to precipitation amounts in the four seasons. The ratios were especially high in winter, higher than those in the other three seasons. ⁷Be deposition flux was estimated by a simple simulation model using atmospheric ⁷Be concentrations and local meteorological data. As a result, the estimated deposition value was relatively lower than the measured value in winter.     

Air mass origins by back trajectory analysis for evaluating atmospheric 210Pb concentrations at Rokkasho, Aomori, Japan

Atmospheric concentrations of ²¹⁰Pb change with various factors such as meso-scale meteorological conditions. We have already reported the biweekly atmospheric ²¹⁰Pb concentrations in Rokkasho, Japan for 5 years and found that they had clear seasonal variations: low concentrations in summer and high values in winter to spring. To study the reasons for the seasonal variations, the origins of the air mass flowing to Rokkasho were analyzed by 3-D backward air mass trajectory analysis. Routes of the calculated trajectories were classified into four regions: northeastern and southeastern Asian Continent, sea and other regions. The atmospheric ²¹⁰Pb concentrations were well correlated with the frequency of the routes through the northeastern Asian Continent. A non-linear multiple regression analysis of the ²¹⁰Pb concentrations and the relative frequencies of the four routes showed good fitting of the predicted values to the observed ones, and indicated that the atmospheric ²¹⁰Pb concentrations in Rokkasho depended on the frequency of the air mass from the northeastern Asian Continent.     

Preparation of radio-Sm by neutron activation for accelerator mass spectrometry

Field measurement of isotopic ratios may be used to fingerprint an element’s origin, be it from commercial power, industrial, medical or historical weapons fallout. Samples of samarium radionuclides were prepared by neutron activation for subsequent analysis using accelerator mass spectrometry (AMS). High purity samarium (III) oxide powder was irradiated in the University of Texas at Austin TRIGA reactor to a total neutron fluence of 5 × 10¹⁵ cm^?2. An initial determination of the isotopic ratios was made using activation calculations with a BURN card in an MCNPX-based model of the TRIGA core. Experimental validation of the MCNP results was achieved by analyzing gamma spectra of the irradiated oxide powers after irradiation. Subsequent measurement of ¹⁵¹Sm will be conducted at the CAMS facility at LLNL demonstrating the first measurement of this isotope at this facility.     

The NAA system at the reactor BER II clinical analysis of fluorine,calcium, phosphorus and aluminium in bone biopsies,comparison with photon activation analysis and ion sensitive electrode

Over the past few years an irradiation and measuring system has been developed for the reactor BER II at the Hahn-Meitner-Institut. It was to be suited in particular to the neutron activation analysis of biological material via short lived radionuclides. The general characteristics of this equipment and some experimental details as the recycling facility and the device used for measuring the irradiation time, the waiting time and the neutron fluence are described. This equipment was used to determine physiological concentrations of the elements sodium, chlorine, aluminium, phosphorus, fluorine, calcium, copper and selenium in biological material. The results have been compared with those obtained by photon activation analysis or ion sensitive electrode. We report on the clinical analysis of Ca, F, P and Al in the control of the treatment of osteoporosis patients and of patients undergoing haemodialysis over long periods as an example of the application of the apparatus. Arbeitsgruppe Spurenelemente in der Biomedizin     

Total deposition velocities and scavenging ratios of 7Be and 210Pb at Rokkasho, Japan

The atmospheric concentrations and deposition fluxes of ⁷Be and ²¹⁰Pb were observed biweekly in Rokkasho, Japan on the Pacific Ocean coast at the northern end of Honshu Island, from March 2000 to March 2006, to clarify their regional features. Seasonal variation pattern of atmospheric ⁷Be concentrations had double peaks, and that of ²¹⁰Pb had a single peak. Deposition fluxes of ⁷Be and ²¹⁰Pb showed the same patterns. The total deposition pattern of ⁷Be was similar to that commonly seen on the Pacific Ocean side of northern Honshu Island, while the pattern of ²¹⁰Pb was similar to that commonly seen on the Japan Sea side. The lack of high spine mountains windward in Rokkasho may be the cause of this ambiguity in the winter monsoon season. Total deposition velocities and scavenging ratios of ²¹⁰Pb were similar to those of ⁷Be from spring to fall, and showed that both nuclides had a similar removal process from the atmosphere. However, the scavenging ratios of ²¹⁰Pb were slightly larger than those of ⁷Be in winter, indicating different behaviors for both nuclides in the scavenging process. The scavenging ratios of both nuclides inversely correlated with precipitation rate, and the ratios in winter were larger than in the other seasons.     

Automation and Quality Assurance in the NAA Facilities in Delft

The facilities for instrumental neutron activation analysis in Delft are described. Technical details of the fast rabbit systems, the normal pneumatic rabbit system, the large sample facility and the various coaxial and well-type Ge-detector spectrometers and sample changers are given. The capacity of the facilities is in the order of 15,000 samples per annum for full multi-element analysis. The capacity of the fast rabbit systems for INAA for use with short half-life radionuclides is even larger. The facilities are accessible for use by scientists from other establishments and countries as well.     

Multielement content of coal by neutron activation analysis techniques

Due to the interaction with components present in natural waters, radionuclides may be present in different physico-chemical forms, varying in size, charge and density. The distribution pattern will influence the transport, mobility and biological uptake of the radionuclides. Size fractionation based on hollow fiber is useful for the determination of the size distribution pattern of radionuclides in natural waters. Furthermore, a continuous mixing and separation system has been developed for the investigation of the association of radionuclides with naturally occurring colloids. Results based on radionuclides in waste water from the Forsmark nuclear power plant, Sweden, will illustrate the potential usefulness of the technique.     

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.     

Distribution and speciation of cesium,strontium, and europium in the aqueous two-phase system milk-pectin

Partition of radionuclides in aqueous liquid-liquid systems allows speciation of bioinorganic forms under nondenaturing conditions. From the fresh pasteurized skim bovine milk spiked with respective radionuclides and agitated with 4% w/w water solution of apple pectin, about 80% of cesium, 22% of strontium and less than 1.5% of europium is recovered with the pectin, phase at an initial milk — pectin volume ratio of 73. This recovery fraction is proportional to the abundance of radionuclides in milk serum. No protein bound fraction of strontium extractable by Aerosol OT in isooctane was obtained. More than 3-fold preconcentration of strontium and europium radionuclides in milk is achieved after 10–15 min membraneless osmosis with pectin phase.     

Comparison studies adsorption of thorium and uranium on pure clay minerals and local Malaysian soil sediments

Adsorption studies of thorium and uranium radionuclides on 9 different pure clay minerals and 4 local Malaysian soil sediments were conducted. Solution containing dissolved thorium and uranium at pH 4.90 was prepared from concentrate sludges from a long term storage facility at a local mineral processing plant. The sludges are considered as low level radioactive wastes. The results indicated that the 9 clay minerals adsorbed more uranium than thorium at pH ranges from 3.74 to 5.74. Two local Malaysian soils were observed to adsorb relatively high concentration of both radionuclides at pH 3.79 to 3.91. The adsorption value 23.27 to 27.04 ppm for uranium and 33.1 to 50.18 ppm for thorium indicated that both soil sediments can be considered as potential enhanced barrier material for sites disposing conditioned wastes containing uranium and thorium.     

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.     

用人工神经网络预测催化精馏塔开工过程的研究

催化精馏是使化学反应过程和精馏分离过程结合在一起,是伴有化学反应的新型特殊精馏过程.“反应精馏”概念自20年代提出以来,从30年代到60年代初,研究都是对特定体系的工艺探索;70年代后,研究扩展到非均相催化反应体系,出现了非均相催化精馏过程,成为了反应精馏的一个重要分支;     

From measurement to dose: Philosophy and practice

The aim of the work is to describe briefly the methodology for establishing and operating an internal dosimetry program in a complex waste processing facility, with special emphasis to the complexity of activities and problems and to the uncertainties in attributing doses from bioassay data. The purpose is not to make a fundamental study of the dosimetric models as such, but to give the viewpoint of the practical health physicist who is confronted with interpretation problems as the consequence of an intake of radionuclides. Some model parameters are discussed in relation to acute or chronic intakes. A practical contamination case is elaborated.     

Reference materials for the radionuclide program – performance evaluation samples

 The U.S. Food and Drug Administration's (FDA) Radionuclides in Food Program was reinstituted in 1973, expanded in 1975 and again in 1990, to its present status. The need for reference materials for radionuclides in food samples was recognized as early as 1962. There were no available reference materials for these types of samples at that time. The materials developed to assure that the results being obtained were acceptable were primarily milk, water and food. The radionuclides of interest were iodine-131, cesium-137 and other short-lived radionuclides found in fission products. These were first issued through the then Health, Education and Welfare Department's Analytical Quality Control Program and, later, in 1970 through the Environmental Protection Agency (EPA). In November 1998, the EPA discontinued this program. The FDA is proposing to reinstitute part of this program, as a primary laboratory, traceable to the National Institute of Technology (NIST) and included in this, the FDA proposes to supply the States and/or their contractors with low-level standards and with milk- and water intercomparison samples. It will also use these results where possible as collaborative studies to validate some of the more recent methods adopted by the American Society for Testing and Materials (ASTM), American Public Health Association (APHA) and Association of Official Analytical Chemists International (AOAC, Int'l.) The FDA will also supply low-level standards to compliment these programs as did the EPA. It is expected that these samples will serve as performance evaluation samples for the States programs.     

Application of the nuclide identification system SHAMAN in monitoring the Comprehensive Test Ban Treaty

SHAMAN is an expert system for qualitative and quantitative radionuclide identification in gamma spectrometry. SHAMAN requires as input the calibrations, peak search, and fitting results from reliable spectral analysis software, such as SAMPO. SHAMAN uses a comprehensive reference library with 2600 radionuclides and 80 000 gamma-lines, as well as a rule base consisting of sixty inference rules. Identification results are presented both via an interactive graphical interface and in the form of configurable text reports. An organization has been established for monitoring the recent Comprehensive Test Ban Treaty. For radionuclide monitoring, 80 stations will be set up around the world. Air-filter gammaspectra will be collected from these stations on a daily basis and they will need to be reliably analyzed with minimum turnaround time. SHAMAN is currently being evaluated within the prototype monitoring system as an automated radionuclide identifier, in parallel with existing radionuclide identification software. In air-filter monitoring, very low concentrations of radionuclides are measured from bulky sources in close geometry and with long counting time. In this case true coincidence summing and self-absorption become important factors. SHAMAN is able to take into account these complicated phenomena, and the results it produces have been found to be very reliable and accurate.