Assessment of fissionable material behaviour in fission chambers

A comprehensive study is performed in order to assess the pertinence of fission chambers coated with different fissile materials for high neutron flux detection. Three neutron scenarios are proposed to study the fast component of a high neutron flux: (i) high neutron flux with a significant thermal contribution such as BR2, (ii) DEMO magnetic fusion reactor, and (iii) IFMIF high flux test module. In this study, the inventory code ACAB is used to analyze the following questions: (i) impact of different deposits in fission chambers; (ii) effect of the irradiation time/burn-up on the concentration; (iii) impact of activation cross-section uncertainties on the composition of the deposit for all the range of burn-up/irradiation neutron fluences of interest. The complete set of nuclear data (decay, fission yield, activation cross-sections, and uncertainties) provided in the EAF2007 data library are used for this evaluation

Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus -- the "D-shuttle" project --

Twelve high schools in Japan (of which six are in Fukushima Prefecture), four in France, eight in Poland and two in Belarus cooperated in the measurement and comparison of individual external doses in 2014. In total 216 high-school students and teachers participated in the study. Each participant wore an electronic personal dosimeter "D-shuttle" for two weeks, and kept a journal of his/her whereabouts and activities. The distributions of annual external doses estimated for each region overlap with each other, demonstrating that the personal external individual doses in locations where residence is currently allowed in Fukushima Prefecture and in Belarus are well within the range of estimated annual doses due to the background radiation level of other regions/countries

LA-UR-01-5681 WASTE CRATE ASSAY SYSTEM (WCAS): ASSAY SOLUTIONS FOR VERY LARGE REMOTE HANDLED CRATES WASTE CRATE ASSAY SYSTEM (WCAS): ASSAY SOLUTIONS FOR VERY LARGE REMOTE HANDLED CRATES

ABSTRACT An advanced passive neutron counter has been designed and fabricated to measure the plutonium content in large remote handled (RH) waste crates. The waste crate assay system (WCAS) was developed under an agreement between Los Alamos National Laboratory, Japan Nuclear Fuel Limited (JNFL), and BNFL Instruments Inc. (BII) to measure the plutonium content in the waste generated in the Rokkasho reprocessing facility. The primary goal of the design was to produce an assay system for large waste containers. The system also includes 200-L drum pallet assay capability. The measurements are based on neutron-time correlation counting of the passive neutron emissions from the 240 Pu, and the plutonium isotopic ratios are used to calculate the total plutonium. The system is designed for both RH waste and low-activity plutonium waste. The system permits the measurement of the singles, doubles, and triples rates and the multiplicity mode analysis is used together with the "add-a-source" method to correct for the matrix materials in the crates. In the multiplicity analysis, the efficiency for counting the neutrons emitted from the crate is directly calculated from the three measured rates. For improved detectability limits, advanced methods have been incorporated in the WCAS-A to reduce the cosmic-ray neutron backgrounds. These methods include statistical filters and truncation of high-multiplicity events. The paper describes the WCAS-A design, performance, and calibration

WASTE CRATE ASSAY SYSTEM (WCAS) : ASSAY SOLUTIONS FOR VERY LARGE REMOTE HANDLED CRATES

An advanced passive neutron counter has been designed and fabricated to measure the plutonium content in large remote handled (RH) waste crates. The waste crate assay system (WCAS) was developed under an agreement between Los Alamos National Laboratory, Japan Nuclear Fuel Limited (JNFL), and BNFL Instruments Inc. (BII) to measure the plutonium content in the waste generated in the Rokkasho reprocessing facility. The primary goal of the design was to produce an assay system for large waste containers. The system also includes 200-L drum pallet assay capability. The measurements are based on neutron-time correlation counting of the passive neutron emissions from the 240Pu, and the plutonium isotopic ratios are used to calculate the total plutonium. The system is designed for both RH waste and low-activity plutonium waste. The system permits the measurement of the singles, doubles, and triples rates and the multiplicity mode analysis is used together with the 'add-a-source' method to correct for the matrix materials in the crates. In the multiplicity analysis, the efficiency for counting the neutrons emitted from the crate is directly calculated from the three measured rates. For improved detectability limits, advanced methods have been incorporated in the WCAS-A to reduce the cosmic-ray neutron backgrounds. These methods include statistical filters and truncation of high-multiplicity events. The paper describes the WCAS-A design, performance, and calibration

Trilobodrilus itoi sp nov., with a Re-Description of T. nipponicus (Annelida: Dinophilidae) and a MolecularPhylogeny of the Genus

The marine interstitial annelid Trilobodrilus itoi sp. nov., the sixth member of the genus, is described on the basis of specimens collected intertidally at Ishikari Beach, Hokkaido, Japan; this is the second species in the genus described from the Pacific Rim. In addition, T. nipponicus Uchida and Okuda, 1943 is re-described based on fresh topotypic material from Akkeshi, Hokkaido, Japan. From both species, we determined sequences of the nuclear 18S and 28S rRNA genes, and the mitochondrial cytochrome c oxidase subunit I (COI) gene. Molecular phylogenetic trees based on concatenated sequences of the three genes showed that T. itoi and T. nipponicus form a clade, which was the sister group to a clade containing the two European congeners T. axi Westheide, 1967 and T. heideri Remane, 1925. The Kimura two-parameter distance for COI was 22.5-22.7% between T. itoi and T. nipponicus, comparable with interspecific values in other polychaete genera. We assessed the taxonomic utility of epidermal inclusions and found that the known six species can be classified into three groups