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Journal Articles

Feasibility study of tritium recoil barrier for neutron reflectors

Ishitsuka, Etsuo; Sakamoto, Naoki*

Physical Sciences and Technology, 6(2), p.60 - 63, 2019/12

https://doi.org/10.26577/phst-2019-2-p8

Tritium release into the primary coolant of the research and test reactors during operation had been studied, and it is found that the recoil release from chain reaction of $^{9}$ Be is dominant. To reduce tritium concentration of the primary coolant, feasibility study of the tritium recoil barrier for the beryllium neutron reflectors was carried out, and the tritium recoils of various materials were calculated by PHITS. From these calculation results, it is clear that the thickness of tritium recoil barrier depends on the material and 2040 m is required for three orders reduction.

Journal Articles

Calculation of tritium release from driver fuels into primary coolant of research reactors

Ho, H. Q.; Ishitsuka, Etsuo

Physical Sciences and Technology, 5(2), p.53 - 56, 2019/00

https://doi.org/10.26577/phst-2018-2-158

Increasing of tritium concentration in the primary coolant of the research and test reactors during operation had been reported. To check the source for tritium release into the primary coolant during operation of the JMTR and the JRR-3M, the tritium release from the driver fuels was calculated by MCNP6 and PHITS. It is clear that the calculated values of tritium release from fuels are as about 10 $^{7}$ and 10 $^{6}$ Bq for the JMTR and JRR-3M, respectively, and that calculated values are about 4 order of magnitude smaller than that of the measured values. These results show that the tritium release from fuels is negligible for both the reactors.

JAEA Reports

Calculations of Tritium Recoil Release from Li and U Impurities in Neutron Reflectors (Joint research)

Ishitsuka, Etsuo; Kenzhina, I.*; Okumura, Keisuke; Ho, H. Q.; Takemoto, Noriyuki; Chikhray, Y.*

JAEA-Technology 2018-010, 33 Pages, 2018/11

JAEA-Technology-2018-010.pdf:2.58MB

As a part of study on the mechanism of tritium release to the primary coolant in research and testing reactors, tritium recoil release rate from Li and U impurities in the neutron reflector made by beryllium, aluminum and graphite were calculated by PHITS code. On the other hand, the tritium production from Li and U impurities in beryllium neutron reflectors for JMTR and JRR-3M were calculated by MCNP6 and ORIGEN2 code. By using both results, the amount of recoiled tritium from beryllium neutron reflectors were estimated. It is clear that the amount of recoiled tritium from Li and U impurities in beryllium neutron reflectors are negligible, and 2 and 5 orders smaller than that from beryllium itself, respectively.

Journal Articles

Evaluation of tritium release curve in primary coolant of research reactors

Ishitsuka, Etsuo; Kenzhina, I. E.*

Physical Sciences and Technology, 4(1), p.27 - 33, 2018/06

https://doi.org/10.26577/phst-2017-1-120

Increase of tritium concentration in the primary coolant for the research and testing reactors during reactor operation had been reported. To clarify the tritium sources, a curve of the tritium release rate into the primary coolant for the JMTR and the JRR-3M are evaluated. It is also observed that the amount of released tritium is lower in the case of new beryllium components installation, and increases with the reactor operating cycle. These results show the beryllium components in core strongly affect to the tritium release into the primary coolant. As a result, the tritium release rate is related with produced $^{6}$ Li by (n,) reaction from $^{9}$ Be, and evaluation results of tritium release curve are shown as the dominant source of tritium release into the primary coolant for the JMTR and the JRR-3M are beryllium components. Scattering of the tritium release rate with irradiation time were observed, and this phenomena in the JMTR occurred in earlier time than that of the JRR-3M.

JAEA Reports

Calculation by PHITS code for recoil tritium release rate from beryllium under neutron irradiation (Joint research)

Ishitsuka, Etsuo; Kenzhina, I. E.*; Okumura, Keisuke; Takemoto, Noriyuki; Chikhray, Y.*

JAEA-Technology 2016-022, 35 Pages, 2016/10

JAEA-Technology-2016-022.pdf:3.73MB

As a part of study on the mechanism of tritium release to the primary coolant in research and testing reactors, the calculation methods by PHITS code is studied to evaluate the recoil tritium release rate from beryllium core components. Calculations using neutron and triton sources were compared, and it is clear that the tritium release rates in both cases show similar values. However, the calculation speed for the triton source cases is two orders faster than that for the neutron source case. It is also clear that the calculation up to history number per unit volume of 210 $^{4}$ (cm $^{-3}$ ) is necessary to determine the recoil tritium release rate of two effective digits precision. Furthermore, the relationship between the beryllium shape and recoil tritium release rate using the triton sources was studied. Recoil tritium release rate showed linear relation to the surface area per volume of beryllium, and the recoil tritium release rate showed about half of the conventional equation value.

Journal Articles

Status of JRR-3 after Great East Japan Earthquake

Arai, Masaji; Wada, Shigeru; Murayama, Yoji

Proceedings of International Topical Meeting on Research Reactor Fuel Management and Meeting of the International Group on Reactor Research (RRFM/IGORR 2016) (Internet), p.403 - 408, 2016/03

In response to the accident at Fukushima Daiichi NPS, the new safety standards for research and test reactor facilities came into force on December 18, 2013. The evaluation of natural disasters and prevention of spread of accidents beyond design basis mainly were enhanced in the standards. We have completed the necessary checks and assessments, and submitted an application for reviewing if JRR-3 complies with the new standards to the Nuclear Regulation Authority on September 26, 2014.

Journal Articles

Introduction to the neutron scattering, 1

Kakurai, Kazuhisa; Endo, Yasuo

Kotai Butsuri, 40(4), p.239 - 250, 2005/04

http://ci.nii.ac.jp/naid/40006691097

no abstracts in English

Journal Articles

Multi-element determination in soil and sediment reference materials by neutron-induced prompt -ray analysis using $_{0}$ -standardization

Matsue, Hideaki; Yonezawa, Chushiro

Bunseki Kagaku, 53(7), p.749 - 751, 2004/07

https://doi.org/10.2116/bunsekikagaku.53.749

Times Cited Count：0 Percentile：0.01(Chemistry, Analytical)

Multi-element determination in reference materials of soils (JASC401, JASC411) and sediments (NMIJ CRM 7302-a, NMIJ CRM 7303-a), which were prepared at the Japan Society for Analytical Chemistry and the National Institute of Advanced Industrial Science and Technology of the National Metrology Institute of Japan, respectively, has been carried out by neutron-induced prompt -ray analysis (PGA) using standard addition and $_{0}$ -standardization methods. Firstly, absolute Ti concentrations in the samples were determined accurately by the standard addition method. Secondly, relative multi-element concentrations were determined by the $_{0}$ -standardization method. Finally, absolute multi-element concentrations were obtained by normalizing the relative multi-element concentrations with the absolute Ti concentration in the samples. The 15 elements such as H, B, Na, Si, S, Cl, K, Ca, Ti Cr, Mn, Fe, Cd, Sm and Gd were determined by the $_{0}$ -PGA. Analytical results of these reference materials agreed with the certified or reference values within about 10%.

Journal Articles

The Recommended k $_{0}$ -factors for neutron-induced prompt -ray analysis and the prompt -ray emission probabilities

Matsue, Hideaki; Yonezawa, Chushiro

Journal of Radioanalytical and Nuclear Chemistry, 262(1), p.49 - 55, 2004/07

https://doi.org/10.1023/B:JRNC.0000040853.53889.34

Times Cited Count：9 Percentile：52.68(Chemistry, Analytical)

The recommended k $_{0}$ factors for 81 -lines of 24 elements, which are useful for neutron induced prompt -ray analysis (PGA) and are not influenced by neutron spectrum difference, were obtained from the k $_{0}$ factors measured with the cold and thermal guided neutron beams of JRR-3M by statistical calculation. The prompt -ray emission probabilities were derived from the recommended k $_{0}$ -factors using atomic weight, isotopic abundance and thermal neutron cross-section of other nuclear constants consisting the k $_{0}$ factors, for which one can obtain accurate data. The derived -ray emission probabilities for the light elements (H to Ca) well agreed within 10% with those of the ENSDF, which reflect recent data, which the agreements for heavy elements (Ti to Pb) were 40% with those of the ENSDF, which are still composed of old data.

Journal Articles

High-pressure apparatus for magnetic neutron diffraction beyond 3 GPa at low temperature

Osakabe, Toyotaka; Kogi, Masafumi*; Kawana, Daichi*; Hannan, A.*; Soyama, Kazuhiko; Kitazawa, Hideaki*

Journal of Magnetism and Magnetic Materials, 272-276, p.2157 - 2158, 2004/05

https://doi.org/10.1016/j.jmmm.2003.12.873

Times Cited Count：3 Percentile：19.92(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Development of thermal neutron focusing device using supermirrors

Osakabe, Toyotaka; Soyama, Kazuhiko; Suzuki, Koji*; Miyo, Tatsuya*

Hamon, 14(1), p.84 - 87, 2004/01

https://doi.org/10.5611/hamon.14.84

The neutron-focusing is an indispensable technical element in the experments under extreme condition with tiny samples. In this article, the development of the thermal neutron focusing device is reported. The device has 18 pieces of the 3Q $_{c}$ NiC/Ti neutron supermirrors with the shape of a circle. The extension of the end of each mirror meets at a focal point (sample position). Neutrons are repeatedly reflected with the same angle by the inner side of the circle and arrive at the sample position. The test results show that the integrated intensity increases by a factor of 2 or more for the neutron wavelength of 2.36AA .

Journal Articles

Measurement and evaluation of k $_{0}$ factors for PGA at JAERI

Matsue, Hideaki; Yonezawa, Chushiro

Journal of Radioanalytical and Nuclear Chemistry, 257(3), p.565 - 571, 2003/09

https://doi.org/10.1023/A:1025492615803

Times Cited Count：7 Percentile：45.83(Chemistry, Analytical)

no abstracts in English

Journal Articles

Low temperature chemistry in research reactor

Aratono, Yasuyuki

Hamon, 13(3), p.168 - 172, 2003/07

https://doi.org/10.5611/hamon.13.168

Recent works on hydrogen abstractions by tritium atom and on recombination reactions of tritium and hydrogen atoms at low temperature(1-2K), which were carried out at JRR-3M by the authors, were introduced.

Journal Articles