True coincidence summing correction for cylindrical volume samples in -ray spectrometry

Yamada, Takashi*; Asai, Masato; Yonezawa, Chushiro*; Kakita, Kazutoshi*; Hirai, Shoji*

Radioisotopes, 69(9), p.287 - 297, 2020/09

https://doi.org/10.3769/radioisotopes.69.287

We have confirmed that the commercially available Japanese "standard" gamma-ray analysis programs do not consider the effect of sample volume in calculating true coincidence summing (TCS) corrections, which results in underestimation of Cs radioactivity in cylindrical volume samples. In this work, we have developed and examined a practical TCS correction method for general Ge detectors which consider the effect of sample volume properly, and have confirmed that this method can reduce the Cs radioactivity underestimation to less than 1%.

Cross-section-induced uncertainty evaluation of MA sample irradiation test calculations with consideration of dosimeter data

Sugino, Kazuteru; Numata, Kazuyuki*; Ishikawa, Makoto; Takeda, Toshikazu*

Annals of Nuclear Energy, 130, p.118 - 123, 2019/08

https://doi.org/10.1016/j.anucene.2019.02.035

In MA sample irradiation test data calculations, the neutron fluence during irradiation period is generally scaled by using dosimetry data in order to improve calculation accuracy. In such a case, appropriate correction is required to burnup sensitivity coefficients obtained by the conventional generalized perturbation theory because some cancellations occur in the burnup sensitivity coefficients. Therefore, a new formula for the burnup sensitivity coefficient has been derived with the consideration of the neutron fluence scaling effect (NFS). In addition, the cross-section-induced uncertainty is evaluated by using the obtained burnup sensitivity coefficients and the covariance data based on the JENDL-4.0.

Results and progress of fundamental research on fission product chemistry; Progress report in 2015

Osaka, Masahiko; Miwa, Shuhei; Nakajima, Kunihisa; Di Lemma, F. G.*; Suzuki, Chikashi; Miyahara, Naoya; Kobata, Masaaki; Okane, Tetsuo; Suzuki, Eriko

JAEA-Review 2016-026, 32 Pages, 2016/12

JAEA-Review-2016-026.pdf:6.18MB

A fundamental research program on fission product (FP) chemistry has started since 2012 for the purpose of establishment of a FP chemistry database in each region of LWR under severe accident and improvement of FP chemical models based on the database. Research outputs are reflected as fundamental knowledge to both the research and development of decommissioning of Fukushima Daiichi Nuclear Power Station (1F) and enhancement of LWR safety. Four research items have thus been established considering the specific issues of 1F and the priority in the source term research area, as follows: effects of boron (B) release kinetics and thermal-hydraulic conditions on FP behavior, cesium (Cs) chemisorption and reactions with structural materials, enlargement of a thermodynamic and thermophysical properties database for FP compounds and development of experimental and analytical techniques for the reproduction of FP behavior and for direct measurement methods of chemical form of FP compounds. In this report, the research results and progress for the year 2015 are described. The main accomplishment was the installation of a reproductive test facility for FP release and transport behavior. Moreover, basic knowledge about the Cs chemisorption behavior was also obtained. In addition to the four research items, a further research item is being considered for deeper interpretation of FP behavior by the analysis of samples outside of the 1F units.

Challenge to ultra-trace analytical techniques of nuclear materials in environmental samples for safeguards at JAERI; Methodologies for physical and chemical form estimation

Usuda, Shigekazu; Yasuda, Kenichiro; Kokubu, Yoko; Esaka, Fumitaka; Lee, C. G.; Magara, Masaaki; Sakurai, Satoshi; Watanabe, Kazuo; Hirayama, Fumio; Fukuyama, Hiroyasu; et al.

International Journal of Environmental Analytical Chemistry, 86(9), p.663 - 675, 2006/08

https://doi.org/10.1080/03067310600583733

The IAEA introduced the environmental sample analysis method, as a powerful tool to detect undeclared nuclear activities, into strengthened safeguards system. The principle of the method is that nuclear signatures can be evidenced if trace amount of nuclear materials in environmental samples taken from inside and outside of nuclear facilities are accurately analyzed. Currently, isotope ratios of uranium and plutonium in "swipe" samples are measured, which are collected in nuclear facilities. In future, the subject of environmental sample analysis will expand to soil, sediment, vegetation, water and airborne dust taken from outside of the nuclear facilities. If physical and chemical form of the nuclear materials is identified, we may estimate their origin, treatment process and migration behavior. This paper deals with the developed analytical techniques for the safeguards environmental samples, the current R&D on techniques related to estimation of the physical and chemical form, and possible analytical methodologies applicable to ultra-trace amounts of nuclear materials.

Report of Examination of the Samples from Core Shroud (2F3-H6a) at Fukushima Dai-ni Nuclear Power Station Unit-3 (Contract Research)

The Working Team for Examination Operation of Samples From Core Shroud at Fukushima Dai-ni Unit-3

JAERI-Tech 2004-044, 92 Pages, 2004/05

JAERI-Tech-2004-044.pdf:15.18MB

The present examination has been performed with the objective to ensure the transparency of the examination as the third-party organization by providing technical basis for identifying the causes of cracking through examination of the sample taken from the cracked region of outer H6a welding portion of the core shroud at Fukushima Dai-ni Nuclear Power Station Unit-3, which was a part of sample stored in the Nippon Nuclear Fuel Development Co., Ltd. in the examination of Tokyo Electric Power Company in 2001. The present examination of the sample was conducted at the post irradiation examination facilities of JAERI. The following findings were obtained from the result of the present examination. (1)Three cracks were observed at the portion 3 to 9mm apart from the weld metal and the maximum depth was about 8mm. (2)Intergranular cracking was observed in almost whole fracture surface. The transgranular cracking was partially observed within the depth of about 300m from the surface. (3)Hardening layer over Hv400 at its maximum was found from the surface to the depth of about 500m. Based on the examination results concerning presence of tensile residual stress by welding and relatively high dissolved oxygen contents in core coolant, it is concluded that the cracks were mainly initiated in the hardening layer by transgranular stress corrosion cracking and propagated along the grain boundaries.

Report of Examination of the Sample from Core Shroud (1F4-H4) at Fukushima Dai-ichi Nuclear Power Station Unit-4 (Contract research)

The Working Team for Examination of the Sample from Core Shrouds and Primary Loop Recirculation Pipi

JAERI-Tech 2004-004, 74 Pages, 2004/02

JAERI-Tech-2004-004.pdf:31.62MB

During the 12th periodical inspection in Fukushima Dai-ichi Nuclear Power Station Unit-4 (BWR, 784MW) of Tokyo Electric Power Company (TEPCO), which has been held from September 1993 to February 1994, cracks were found at welded joints No.H4 in the core shroud middle shell. TEPCO has conducted a material examination with Nippon Nuclear Fuel Development Co. Ltd. (NFD) on the SUS304L specimen including cracks sampled from the inner surface of welded joints (H4) of the middle shell of the core shroud. The present examination has been performed with the objective to independently investigate and evaluate the materials by jointly attending the examination with NFD, receiving the final data given by the examination and providing a JAERI's own evaluation report as a third-party organization for assuring the transparency. Based on the research results described above, presence of tensile residual stress by welding and relatively high dissolved oxygen contents in core coolant, it is concluded that the cracks observed were caused by the stress corrosion cracking (SCC).

Establishment of a clean chemistry laboratory at JAERI; Clean Laboratory for Environmental Analysis and Research (CLEAR)

Hanzawa, Yukiko; Magara, Masaaki; Watanabe, Kazuo; Esaka, Fumitaka; Miyamoto, Yutaka; Yasuda, Kenichiro; Gunji, Katsubumi*; Yamamoto, Yoichi; Takahashi, Tsukasa; Sakurai, Satoshi; et al.

JAERI-Tech 2002-103, 141 Pages, 2003/02

JAERI-Tech-2002-103.pdf:10.38MB

The JAERI has established a facility with a cleanroom: the Clean Laboratory for Environmental Analysis and Research (CLEAR). This report is an overview of the design, construction and performance evaluation of the CLEAR in the initial stage of the laboratory operation in June 2001. The CLEAR is a facility to be used for ultra trace analyses of nuclear materials in environmental samples for the safeguards, for the CTBT verification and for researches on environmental sciences. The CLEAR meets double requirements of a cleanroom and for handling of nuclear materials. Much attention was paid to the construction materials of the cleanroom for trace analysis of metal elements using corrosive acids. The air conditioning and purification system, experimental equipment, utilities and safety systems are also demonstrated. The potential contamination from the completed cleanroom atmosphere during the analytical procedure was evaluated. It can be concluded that the CLEAR has provided a suitable condition for reliable analysis of ultra trace amounts of nuclear materials in environmental samples.

Analysis of axial distribution of BC and Pu sample worths in FCA assembly XVII-1

Nagaya, Yasunobu; Ono, Akio; Osugi, Toshitaka

JAERI-Research 95-003, 40 Pages, 1995/01

JAERI-Research-95-003.pdf:1.37MB

no abstracts in English

Gibbs free energies of formation of molybdenum carbide and tungsten carbide from 1173 to 1573K

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Metall.Trans.,A, 17, p.2031 - 2034, 1986/00

no abstracts in English

Light absorption spectrum of radioactive methyl iodide in air

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Nihon Genshiryoku Gakkai-Shi, 25(8), p.658 - 663, 1983/00

https://doi.org/10.3327/jaesj.25.658

no abstracts in English