Event report of JHPS Symposium 2022

Yasuoka, Yumi*; Fujita, Hiroki; Tsuji, Tomoya; Tsujiguchi, Takakiyo*; Sasaki, Michiya*; Miyazaki, Tomoyuki*; Hashima, Shun*; Yasuda, Hiroshi*; Shimada, Kazumasa; Hirota, Seiko*

Hoken Butsuri (Internet), 57(3), p.146 - 155, 2022/12

https://doi.org/10.5453/jhps.57.146

no abstracts in English

Decommissioning of research facilities

Tsuji, Tomoyuki

Genshiryoku Nenkan 2020, p.169 - 171, 2019/10

no abstracts in English

Development of the reasonable confirmation methods concerning radioactive wastes from research facilities

Hayashi, Hirokazu; Okada, Shota; Izumo, Sari; Hoshino, Yuzuru; Tsuji, Tomoyuki; Nakata, Hisakazu; Sakai, Akihiro; Amazawa, Hiroya; Sakamoto, Yoshiaki

Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 7 Pages, 2017/04

A near surface disposal for low-level radioactive waste (LLW) generated from commercial nuclear power plants (NPP) is operating in Japan. However, the disposal of LLW from other nuclear facilities and radioisotope utilization facilities has not yet been implemented. Japan Atomic Energy Agency (JAEA) plans to implement the near surface disposal. In order to be disposed of these wastes, it must be confirmed by the regulator that each waste package (radioactive waste solidified with filling materials, such as cement, in a container by a regulated method is termed a waste package) conforms to technical standards that aim for safe disposal. JAEA has studied reasonable confirmation methods to demonstrate the conformity of the waste package to the technical standard as NPP operators have studied it. This report describes the outline of our activities focused on development of the confirmation method applicable to radioactive wastes from research facilities.

Waste acceptance criteria for waste packages destined for near surface disposal containing radioactive waste from research, industrial and medical facilities

Nakata, Hisakazu; Sakai, Akihiro; Okada, Shota; Izumo, Sari; Tsuji, Tomoyuki; Kurosawa, Ryohei; Amazawa, Hiroya

JAEA-Technology 2016-001, 112 Pages, 2016/03

JAEA-Technology-2016-001.pdf:16.71MB

The waste packages must meet the technical requirements that radioactive waste shall be solidified in a container by a method determined by the Nuclear Regulation Authority to prevent from radiation hazards. JAEA has been preparing operating procedure manual on quality control for radioactive waste disposal in order to promote the manufacturing the waste package. This report presents that simulant waste packages were produced by placing wastes in a 200 liter drum, which was then filled with mortar of a novel mix proportion, followed by curing in a controlled manner. Determination of the presence of harmful voidage and raw waste immobility were performed by direct measurement and visual inspection of a vertical cross section of the waste packages respectively.

Study on the evaluation methods to determine the radioactivity concentration in low-level radioactive wastes generated from JPDR facilities, 2

Tsuji, Tomoyuki; Sakai, Akihiro; Izumo, Sari; Amazawa, Hiroya

JAEA-Technology 2015-009, 46 Pages, 2015/06

JAEA-Technology-2015-009.pdf:1.45MB

It is necessary to establish practical evaluation methods to determine radioactivity concentrations of the important nuclides for safety assessment on disposal of radioactive wastes in order to dispose of low-level radioactive wastes generated from various nuclear facilities in JAEA. In this report, it has been studied that the practical evaluation methods are applied for the important nuclides (H-3, C-14, Cl-36, Ni-59, Co-60, Ni-63, Sr-90, Mo-93, Nb-94, Tc-99, Ag-108m, Cs-137, Eu-152, Eu-154, Ho-166m, nuclides) of radioactive wastes generated from JPDR facilities. As a result, it has been found that the appropriate methods to determine radioactivity concentrations such as the scaling factor method (Ni-63, Nb-94), the mean activity concentration method (H-3, C-14, Cl-36 and so on) and the theoretical method (Ni-59) can be applied and Co-60, Ag-108m and Cs-137 will be evaluated by measurements from outside of the waste package.

Development of the assessment tool for has migration scenario concerning sub-surface disposal

Sakatani, Keiichi; Nakamura, Yasuo; Tsuji, Tomoyuki; Nakatani, Takayoshi

JAEA-Data/Code 2014-020, 38 Pages, 2014/11

JAEA-Data-Code-2014-020.pdf:30.04MB

The safety assessment for sub-surface disposal of radioactive wastes should ensure that calculated dose will be lower than the dose assigned to the scenario in question over the whole evaluation period of hundreds of thousands years. We have developed several assessment tools for the safe disposal of radioactive wastes on the GoldSim platform, and calculated doses since JFY 2008. These assessment tools have been improved reflecting the last view of assessment. In addition, we have developed an assessment tool for the gas migration scenario. This report describes concept of assessment model and structure of tool for the gas migration scenario.

Analysis of the radioactivity concentrations in low-level radioactive waste generated from JPDR facilities, 2

Tanaka, Kiwamu; Yasuda, Mari; Watanabe, Koichi; Hoshi, Akiko; Tsuji, Tomoyuki; Higuchi, Hidekazu

JAEA-Data/Code 2013-008, 16 Pages, 2013/11

JAEA-Data-Code-2013-008.pdf:2.41MB

Simple and rapid methods to evaluate the radioactivity concentrations are required to be established for the near surface disposal of radioactive wastes generated from research facilities at Japan Atomic Energy Agency. In order to establish the methods to evaluate the radioactivity concentrations of miscellaneous solid wastes generated from research and testing reactors, we collected and analyzed samples from miscellaneous solid wastes generated by the decommissioning of JPDR (Japan Power Demonstration Reactor). In the present paper, we summarized data about the radioactivity concentrations which accumulated by the analysis.

Study on the evaluation method to determine the radioactivity concentration in the bituminized products generated from research facilities

Tsuji, Tomoyuki; Kameo, Yutaka; Sakai, Akihiro; Amazawa, Hiroya; Takahashi, Kuniaki

JAEA-Technology 2011-028, 66 Pages, 2011/11

JAEA-Technology-2011-028.pdf:3.16MB

In order to dispose of low-level radioactive wastes generated from various nuclear facilities in JAEA, we need to establish practical evaluation methods to determine radioactivity concentrations of the important nuclides for safety assessment on disposal of radioactive wastes. In this report, we have studied on establishing the practical evaluation methods such as the scaling factor method for bituminized products generated at Nuclear Science Research Institute and also summarized subjects for establishment of the practical evaluation methods for the bituminized products.

Analysis of the radioactivity concentrations in asphalt- or cement-solidified products generated from research facilities

Hoshi, Akiko; Kameo, Yutaka; Katayama, Atsushi; Sakai, Akihiro; Tsuji, Tomoyuki; Nakashima, Mikio; Kihara, Shinji; Takahashi, Kuniaki

JAEA-Data/Code 2009-023, 84 Pages, 2010/03

JAEA-Data-Code-2009-023.pdf:12.81MB

In order to establish the practical evaluation methods such as scaling factor method to determine the radioactivity concentrations of the important nuclides for safety assessment of disposal of radioactive wastes, we analyzed low-level radioactive liquid waste (56 samples), which is generated from various research facilities at Nuclear Science Research Institute from FY1998 to FY2007 and accumulated the radioactivity concentrations data (563 data) of the 17 important nuclides. We investigated the correlation of the radioactivity concentrations of the important nuclides with the "Key nuclides (Co or Cs)". In present paper, the radioactivity concentrations data of the 17 important nuclides and the results of the correlation of the radioactivity concentrations are summarized for the data to establish the practical evaluation methods to determine the radioactivity concentrations in asphalt-solidified or cement-solidified products.

Verification on reliability of diaphragm seal

Ide, Hiroshi; Sakuta, Yoshiyuki; Hanawa, Yoshio; Tsuji, Tomoyuki; Tsuboi, Kazuaki; Nagao, Yoshiharu; Miyazawa, Masataka

JAEA-Technology 2009-019, 28 Pages, 2009/06

JAEA-Technology-2009-019.pdf:41.1MB

The main body of the JMTR is composed of reactor pressure vessel, core and reactor pool. At the bottom of the reactor pool, the Diaphragm-seal (2.6m outer diameter, 2m inner diameter, thickness 1.5mm) of the JMTR made of stainless steel is installed to prevent the water leak of the reactor pool and to absorb the expansion of the reactor pressure vessel due to pressure and temperature changes. Prior to the refurbishment of the JMTR, the inspection device which is a deposition-collection apparatus with underwater-camera was developed, and the visual inspection was carried out to confirm the soundness of the diaphragm-seal. As a result, harmful flaws and/or corrosions were not inspected in the visual inspection, and the soundness of the diaphragm seal was confirmed. In future, the long-term integrity of the diaphragm-seal will could be achieved by conducting the periodic inspection.