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JAEA Reports

Analysis of the radioactivity concentrations in radioactive waste generated from JRR-3, JRR-4 and JRTF facilities

Tobita, Minoru*; Konda, Miki; Omori, Takeshi*; Nabatame, Tsutomu*; Onizawa, Takashi*; Kurosawa, Katsuaki*; Haraga, Tomoko; Aono, Ryuji; Mitsukai, Akina; Tsuchida, Daiki; et al.

JAEA-Data/Code 2022-007, 40 Pages, 2022/11

JAEA-Data-Code-2022-007.pdf:1.99MB

Radioactive wastes generated from nuclear research facilities in Japan Atomic Energy Agency are planning to be buried in the near surface disposal field. Therefore, it is required to establish the method to evaluate the radioactivity concentrations of radioactive wastes until the beginning of disposal. In order to contribute to this work, we collected and analyzed concrete, ash, ceramic and brick samples generated from JRR-3, JRR4 and JRTF facilities. In this report, we summarized the radioactivity concentrations of 24 radionuclides ($$^{3}$$H, $$^{14}$$C, $$^{36}$$Cl, $$^{41}$$Ca, $$^{60}$$Co, $$^{63}$$Ni, $$^{90}$$Sr, $$^{94}$$Nb, $$^{99}$$Tc, $$^{rm 108m}$$Ag, $$^{129}$$I, $$^{137}$$Cs, $$^{133}$$Ba, $$^{152}$$Eu, $$^{154}$$Eu, $$^{rm 166m}$$Ho, $$^{234}$$U, $$^{238}$$U, $$^{238}$$Pu, $$^{239}$$Pu, $$^{240}$$Pu, $$^{241}$$Am, $$^{243}$$Am, $$^{244}$$Cm) which were obtained from radiochemical analysis of the samples in fiscal years 2020-2021.

JAEA Reports

Radiation monitoring using manned helicopter around the Nuclear Power Station in the fiscal year 2015 (Contract research)

Sanada, Yukihisa; Munakata, Masahiro; Mori, Airi; Ishizaki, Azusa; Shimada, Kazumasa; Hirouchi, Jun; Nishizawa, Yukiyasu; Urabe, Yoshimi; Nakanishi, Chika*; Yamada, Tsutomu*; et al.

JAEA-Research 2016-016, 131 Pages, 2016/10

JAEA-Research-2016-016.pdf:20.59MB

By the nuclear disaster of Fukushima Daiichi Nuclear Power Station (FDNPS), Tokyo Electric Power Company (TEPCO), caused by the East Japan earthquake and the following tsunami occurred on March 11, 2011, a large amount of radioactive materials was released from the NPS. After the nuclear disaster, airborne radiation monitoring using manned helicopter was conducted around FDNPS. In addition, background dose rate monitoring was conducted around Sendai Nuclear Power Station. These results of the aerial radiation monitoring using the manned helicopter in the fiscal 2015 were summarized in the report.

Journal Articles

Demonstration result of sample assay system equipped alternative He-3 detectors

Tanigawa, Masafumi; Mukai, Yasunobu; Tobita, Hiroshi; Kurata, Noritaka*; Kobayashi, Nozomi*; Takase, Misao*; Makino, Risa; Ozu, Akira; Nakamura, Hironobu; Kurita, Tsutomu; et al.

56th Annual Meeting of the Institute of Nuclear Materials Management (INMM 2015), Vol.1, p.693 - 701, 2016/00

no abstracts in English

Journal Articles

Development of sample assay system equipped with $$^{3}$$He Alternative Neutron Detectors (ASAS), 1; Design and fabrication of ASAS detector

Ozu, Akira; Tobita, Hiroshi; Kureta, Masatoshi; Tanigawa, Masafumi; Mukai, Yasunobu; Nakamichi, Hideo; Nakamura, Hironobu; Kurita, Tsutomu; Seya, Michio

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-36-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/12

Against the background of the serious shortage of $$^{3}$$He gas, the Japan Atomic Energy Agency (JAEA) has newly developed an alternative ZnS ceramic scintillation neutron detector for the safeguards, with the support of the government (MEXT). A demonstrator of plutonium inventory sample assay system (ASAS) has been also developed as an alternative HLNCC (High Level Neutron Coincidence Counter). The results from numerical simulations using Monte-Carlo code MCNPX showed that the fundamental performances of ASAS equipped with the 24 alternative neutron detectors, such as neutron detection efficiency and die-away time, equal to or higher than those of conventional HLNCC could be obtained. Here we present the inner mechanical structure of ASAS, together with the results of the simulating design.

Journal Articles

Development of sample assay system equipped with $$^{3}$$He Alternative Neutron Detectors (ASAS), 2; Results of ASAS measurement test

Tanigawa, Masafumi; Mukai, Yasunobu; Kurita, Tsutomu; Makino, Risa; Nakamura, Hironobu; Tobita, Hiroshi; Ozu, Akira; Kureta, Masatoshi; Seya, Michio

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-36-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2015/12

Against the background of the serious shortage of $$^{3}$$He gas, design and development of a new detector equipped ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillation neutron detectors in JAEA, with the support of the government (the Ministry of Education, Culture, Sports, Science & Technology). The design of the alternative $$^{3}$$He detector is referred from INVS (INVentory Sample assay system (HLNCC (High Level Neutron Coincidence Counter) type)) which is being used for the verification of MOX powder etc. and is named it as ASAS (Alternative Sample Assay System). In order to prove the Pu quantitative performance as an alternative technology, several measurement tests and comparison test with INVS were conducted using ASAS. In these tests, evaluation of fundamental performance (counting efficiency and die-away time) and uncertainty evaluations were implemented. As a result, although fundamental performance of ASAS was not achieved to the one of INVS, we could confirm that ASAS has almost the same Pu quantitative performance including measurement uncertainty as that of INVS.

Journal Articles

Demonstration result of sample assay system equipped alternative He-3 detectors

Nakamura, Hironobu; Mukai, Yasunobu; Tobita, Hiroshi; Nakamichi, Hideo; Ozu, Akira; Kureta, Masatoshi; Kurita, Tsutomu; Seya, Michio

Proceedings of 37th ESARDA Annual Meeting (Internet), p.45 - 53, 2015/08

JAEA conducted an R&D project to develop a new type of neutron detector using ZnS/$$^{10}$$B$$_{2}$$O$$_{3}$$ ceramic scintillator (as an alternative neutron detector to He-3) with support of Japanese government. The design of the JAEAs alternative system (ASAS: Alternative Sample Assay System using ceramic scintillator tubes) refers basically to the INVS (INVentory Sample assay system) which is the passive type of neutron assay system equipped total 18 He-3 tubes and capable of measuring the small amount of Pu in the MOX powder or Pu nitrate solution in a vial for nuclear material accountancy and safeguards verification. In order to prove the alternative technology and the performance instead of He-3 detector, and to establish Pu measurement capability, JAEA developed and fabricated ASAS equipped 24 alternative ceramic scintillator tubes (which is equivalent to the same counting efficiency of INVS) and demonstrated. The demonstration activity implemented the confirmation of reproducibility about sample positioning, optimization of detector parameters, counting statistical uncertainty, stability check and figure of merit (FOM) using Cf check source and actual MOX powder in PCDF (Plutonium Conversion Development Facility). In addition, performance comparison between the current INVS and the ASAS was also implemented. In this paper, we present demonstration results with design information with Monte-Carlo simulation code (MCNP).

JAEA Reports

Irradiation performance test of the temperature monitor for the HTGR fuel

Ueta, Shohei; Tobita, Tsutomu*; Sawa, Kazuhiro; Tomimoto, Hiroshi; Kozawa, Takayuki; Inoi, Hiroyuki; Umeda, Masayuki

JAEA-Research 2008-096, 34 Pages, 2009/01

JAEA-Research-2008-096.pdf:10.12MB

The temperature monitors for fuel blocks in high temperature gas reactors during operation are being developed. The temperature monitors consist of alloy wires, with various melting points, sealed in quarts capsules. The temperature can be evaluated in the range from 600 to 1400 $$^{circ}$$C with 22 types of the temperature monitors. The temperature monitors have been irradiated by the capsule in JMTR, and then, PIEs such as X-ray radiograph and EPMA have been carried out. As the results of the PIE, it was estimated that the temperature monitors can be used up to 90 days at 1100 $$^{circ}$$C, or up to 50 days at 1300$$sim$$1350 $$^{circ}$$C.

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

Investigation of irradiation behavior of SiC-coated fuel particle at extended burnup

Sawa, Kazuhiro; Tobita, Tsutomu*

Nuclear Technology, 142(3), p.250 - 259, 2003/06

 Times Cited Count:12 Percentile:64.72(Nuclear Science & Technology)

The maximum burnup of the first-loading fuel of the HTTR is limited to 3.6%FIMA to certify its integrity during the operation. In order to investigate fuel behavior under extended burnup condition, irradiation tests were performed. The thickness of buffer and SiC layers of the irradiated fuel particles were increased to keep their integrity up to over 5%FIMA. The fuel compacts were irradiated in independent capsules at the HFIR of ORNL, and at the JMTR of JAERI, respectively. The comparison of measured and calculated (R/B)s showed that additional failures occurred in both irradiation tests. A pressure vessel failure model analysis showed that no tensile stresses acted on the SiC layers even at the end of irradiation and no pressure vessel failure occurred in the intact particles. The presumed failure mechanisms are additional through-coatings failure of as-fabricated SiC-failed particles or an excessive increase of internal pressure by the accelerated irradiation. The further study is needed to clarify the failure mechanism.

JAEA Reports

Plan to development of ZrC-TRISO coated fuel particle and construction of ZrC coater

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

JAERI-Tech 2002-085, 41 Pages, 2002/11

JAERI-Tech-2002-085.pdf:2.66MB

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

Acceleration irradiation test of first-loading fuel of High Temperature Engineering Test Reactor (HTTR) up to high burnup (Joint research)

Sawa, Kazuhiro; Sumita, Junya; Ueta, Shohei; Takahashi, Masashi; Tobita, Tsutomu*; Hayashi, Kimio; Saito, Takashi; Suzuki, Shuichi*; Yoshimuta, Shigeharu*; Kato, Shigeru*

JAERI-Research 2002-012, 39 Pages, 2002/06

JAERI-Research-2002-012.pdf:3.12MB

no abstracts in English

JAEA Reports

Design of high temperature irradiation materials inspection cells (spent fuel inspection cells) in the High Temperature engineering Test Reactor

Ino, Hiroichi*; Ueta, Shohei; Suzuki, Hiroshi; Tobita, Tsutomu*; Sawa, Kazuhiro

JAERI-Tech 2001-083, 46 Pages, 2002/01

JAERI-Tech-2001-083.pdf:6.31MB

no abstracts in English

JAEA Reports

Irradiation test of high burnup coated fuel particles for High Temperature Gas-cooled Reactor; 91F-1A Sweap gas capsule irradiation test

Sawa, Kazuhiro; Tobita, Tsutomu*; Takahashi, Masashi; Saito, Takashi; Iimura, Katsumichi; Yokouchi, Iichiro; Serizawa, Hiroyuki; Sekino, Hajime; Ishikawa, Akiyoshi

JAERI-Research 2001-043, 52 Pages, 2001/09

JAERI-Research-2001-043.pdf:14.92MB

no abstracts in English

Journal Articles

Integrity confirmation tests and post-irradiation test plan of the HTTR first-loading fuel

Sawa, Kazuhiro; Sumita, Junya; Ueta, Shohei; Suzuki, Shuichi*; Tobita, Tsutomu*; Saito, Takashi; Minato, Kazuo; Koya, Toshio; Sekino, Hajime

Journal of Nuclear Science and Technology, 38(6), p.403 - 410, 2001/06

 Times Cited Count:7 Percentile:48.69(Nuclear Science & Technology)

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

A Study of mechanical integrity of coated particle fuel under high burnup irradiation

Sawa, Kazuhiro; Ueta, Shohei; Sumita, Junya; Tobita, Tsutomu*; Minato, Kazuo

Transactions of 16th International Conference on Structural Mechanics in Reactor Technology (SMiRT-16) (CD-ROM), 11 Pages, 2001/00

no abstracts in English

JAEA Reports

A Conceptual study of oxidization resistant fuel compact for High Temperature Gas-cooled Reactors

Sawa, Kazuhiro; Tobita, Tsutomu*; Suzuki, Shuichi*; Yoshimuta, Shigeharu*; Oda, Takefumi*; Watarumi, Kazutoshi*

JAERI-Tech 99-077, p.41 - 0, 1999/11

JAERI-Tech-99-077.pdf:5.23MB

no abstracts in English

Journal Articles

Fabrication of the first-loading-fuel of the High Temperature engineering Test Reactor

Sawa, Kazuhiro; Tobita, Tsutomu*; Mogi, Haruyoshi; Shiozawa, Shusaku; Yoshimuta, Shigeharu*; Suzuki, Shuichi*; *

Journal of Nuclear Science and Technology, 36(8), p.683 - 690, 1999/08

 Times Cited Count:32 Percentile:88.99(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Establishment of handling technique for permanent neutron startup sources of the high temperature engineering test reactor

Takeda, Takeshi; Tobita, Tsutomu*; Mogi, Haruyoshi; *

JAERI-Tech 99-053, 57 Pages, 1999/07

JAERI-Tech-99-053.pdf:2.91MB

no abstracts in English

54 (Records 1-20 displayed on this page)