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Journal Articles

Feasibility study on tritium recoil barrier for neutron reflectors of research and test reactors

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

Fusion Engineering and Design, 164, p.112181_1 - 112181_5, 2021/03

Tritium release into the primary coolant during operation of the JMTR (Japan Materials Testing Reactor) and the JRR-3M (Japan Research Reactor-3M) had been studied. It is found that the recoil release by $$^{6}$$Li(n$$_{t}$$,$$alpha$$)$$^{3}$$H reaction, which comes from a chain reaction of beryllium neutron reflectors, is dominant. To prevent tritium recoil release, the surface area of beryllium neutron reflectors needs to be minimum in the core design and/or be shielded with other material. In this paper, as the feasibility study of the tritium recoil barrier for the beryllium neutron reflectors, various materials such as Al, Ti, V, Ni, and Zr were evaluated from the viewpoint of the thickness of barriers, activities after long-term operations, and effects on the reactivities. From the results of evaluations, Al would be a suitable candidate as the tritium recoil barrier for the beryllium neutron reflectors.

Journal Articles

Evaluation of tritium release into primary coolant for research and testing reactors

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

Journal of Nuclear Science and Technology, 58(1), p.1 - 8, 2021/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The sources and mechanisms for the tritium release into the primary coolant in the JMTR and the JRR-3M containing beryllium reflectors are evaluated. It is found that the recoil release from chain reaction of $$^{9}$$Be is dominant and its calculation results agree well with trends derived from the measured variation of tritium concentration in the primary coolant. It also indicates that the simple calculation method used in this study for the tritium recoil release from the beryllium reflectors can be utilized for an estimation of the tritium release into the primary coolant for a research and testing reactors containing beryllium reflectors.

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

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 20$$sim$$40 $$mu$$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

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

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,$$alpha$$) 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 2$$times$$10$$^{4}$$ (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

A Modelling study on water radiolysis for primary coolant in PWR

Mukai, Satoru*; Umehara, Ryuji*; Hanawa, Satoshi; Kasahara, Shigeki; Nishiyama, Yutaka

Proceedings of 20th International Conference on Water Chemistry of Nuclear Reactor Systems (NPC 2016) (USB Flash Drive), 9 Pages, 2016/10

In Japanese PWR, the concentration of dissolved hydrogen in the primary coolant is controlled in the range from 25 cc/kg-H$$_{2}$$O to 35 cc/kg-H$$_{2}$$O for suppression of water decomposition. However this concentration is desired to reduce for the purpose of radiation source reduction in Japan. So, the concentration due to water radiolysis in primary coolant was evaluated at lower hydrogen concentration by the water radiolysis model in consideration of $$gamma$$ ray, fast neutron and alpha ray due to the reaction $$^{10}$$B(n,$$alpha$$)$$^{7}$$Li. The results of evaluation showed that the water radiolysis was suppressed even if the hydrogen concentration was decreased to 5 cc/kg-H$$_{2}$$O. The effects of the different G-value and the rate constants of major reaction on the concentration of H$$_{2}$$O$$_{2}$$ and O$$_{2}$$ were studied under hydrogen addition. We also focused on the effect of the alpha radiolysis in boron acid water.

JAEA Reports

An Investigation of fuel and fission product behavior in rise-to-power test of HTTR, 2; Results up to 30 MW operation

Ueta, Shohei; Emori, Koichi; Tobita, Tsutomu*; Takahashi, Masashi*; Kuroha, Misao; Ishii, Taro*; Sawa, Kazuhiro

JAERI-Research 2003-025, 59 Pages, 2003/11

JAERI-Research-2003-025.pdf:2.53MB

In the safety design requirements for the High Temperature Engineering Test Reactor (HTTR) fuel, it is determined that "the as-fabricated failure fraction shall be less than 0.2%" and "the additional failure fraction shall be small through the full service period". Therefore the failure fraction should be quantitatively evaluated during the HTTR operation. In order to measure the primary coolant activity, primary coolant radioactivity signals the in safety protection system, the fuel failure detection (FFD) system and the primary coolant sampling system are provided in the HTTR. The fuel and fission product behavior was evaluated based on measured data in the rise-to-power tests (1) to (4). The measured fractional releases are constant at 2$$times$$10$$^{-9}$$ up to 60% of the reactor power, and then increase to 7$$times$$10$$^{-9}$$ at full power operation. The prediction shows good agreement with the measured value. These results showed that the release mechanism varied from recoil to diffusion of the generated fission gas from the contaminated uranium in the fuel compact matrix.

Journal Articles

Fuel and fission gas behavior during rise-to-power test of the High Temperature engineering Test Reactor (HTTR)

Ueta, Shohei; Sumita, Junya; Emori, Koichi; Takahashi, Masashi*; Sawa, Kazuhiro

Journal of Nuclear Science and Technology, 40(9), p.679 - 686, 2003/09

 Times Cited Count:12 Percentile:64.02(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Calibration test of $$gamma$$-energy analysis system for fuel and fission gas behavior during High Temperature Engineering Test Reactor operation

Ueta, Shohei; Tobita, Tsutomu*; Takahashi, Masashi*; Sawa, Kazuhiro

JAERI-Tech 2002-055, 24 Pages, 2002/07

JAERI-Tech-2002-055.pdf:1.04MB

no abstracts in English

JAEA Reports

An Investigation of fuel and fission product behavior in start-up test of HTTR, 1; Result up to 15MW operation

Sawa, Kazuhiro; Tobita, Tsutomu*; Ueta, Shohei; Suzuki, Shuichi*; Sumita, Junya; Sekita, Kenji; Aoki, Kazunori*; Ouchi, Hiroshi

JAERI-Research 2001-002, 33 Pages, 2001/02

JAERI-Research-2001-002.pdf:1.42MB

no abstracts in English

Journal Articles

Evaluation method of performance of siphon break value as core covering system for water-cooled test and research reactors

; Kumada, Hiroaki; Kaminaga, Fumito*

Nihon Genshiryoku Gakkai-Shi, 42(4), p.325 - 333, 2000/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Impurity measurement test of HTTR; At the commissioning tests

Sakaba, Nariaki; Emori, Koichi; Saruta, Toru

JAERI-Tech 99-072, p.125 - 0, 1999/10

JAERI-Tech-99-072.pdf:5.85MB

no abstracts in English

JAEA Reports

Fuel failure and fission gas release analysis code in HTGR

Sawa, Kazuhiro; Sumita, Junya; Watanabe, Takashi*

JAERI-Data/Code 99-034, 115 Pages, 1999/06

JAERI-Data-Code-99-034.pdf:3.65MB

no abstracts in English

JAEA Reports

The Heavy water accountancy for research reactors in JAERI

; ;

JAERI-Tech 98-052, 69 Pages, 1998/11

JAERI-Tech-98-052.pdf:3.28MB

no abstracts in English

JAEA Reports

Counter-measure to prevent temperature rise of stand pipe and primary upper shielding in HTTR

Kunitomi, Kazuhiko; Tachibana, Yukio; *; Nakano, Masaaki*; Saikusa, Akio; Takeda, Takeshi; Iyoku, Tatsuo; ; Sawahata, Hiroaki; Okubo, Minoru; et al.

JAERI-Tech 97-040, 91 Pages, 1997/09

JAERI-Tech-97-040.pdf:2.51MB

no abstracts in English

JAEA Reports

Chemistry and radiochemistry tests of N.S.MUTSU; Reports on N.S.MUTSU power-up tests

; *; *; ;

JAERI-M 92-002, 56 Pages, 1992/02

JAERI-M-92-002.pdf:1.92MB

no abstracts in English

Journal Articles

Journal Articles

Present state of decontamination technology for nuclear rectors

;

Boshoku Gijutsu, 32, p.721 - 729, 1983/00

no abstracts in English

23 (Records 1-20 displayed on this page)