Stabilization of post-experiment nuclear materials in Plutonium Fuel Research Facility

Sato, Takumi; Otobe, Haruyoshi; Morishita, Kazuki; Marufuji, Takato; Ishikawa, Takashi; Fujishima, Tadatsune; Nakano, Tomoyuki

JAEA-Technology 2023-016, 41 Pages, 2023/09

JAEA-Technology-2023-016.pdf:2.74MB

This report summarizes the results of the stabilization treatments of post-experiment nuclear materials in Plutonium Fuel Research Facility (PFRF) from August 2018 to March 2021. Based on the management standards for nuclear materials enacted after the contamination accident that occurred at PFRF on June 6, 2017, the post-experiment nuclear materials containing plutonium (Pu): samples mixed with organic substances that cause an increase in internal pressure due to radiolysis (including X-ray diffraction samples mixed with epoxy resin and plutonium powder which caused contamination accidents), carbides and nitrides samples which is reactive in air, and chloride samples which may cause corrosion of storage containers, were selected as targets of the stabilization. The samples containing organic materials, carbides and nitrides were heated in an air flow at 650 C and 950 C for 2 hours respectively to remove organic materials and convert uranium (U) and Pu into oxides. U and Pu chlorides in LiCl-KCl eutectic melt were reduced and extracted into liquid Cd metal by a reaction with lithium (Li) -cadmium (Cd) alloy and converted to U-Pu-Cd alloy at 500 C or higher. All of the samples were stabilized and stored at PFRF. We hope that the contents of this report will be utilized to consider methods for stabilizing post experiment nuclear materials at other nuclear fuel material usage facilities.

Technical design of the pressure-resistant chamber for open inspections of the storage containers of nuclear fuel materials

Marufuji, Takato; Sato, Takumi; Ito, Hideaki; Suzuki, Hisashi; Fujishima, Tadatsune; Nakano, Tomoyuki

JAEA-Technology 2019-006, 22 Pages, 2019/05

JAEA-Technology-2019-006.pdf:2.84MB

Radioactive contamination incident occurred at Plutonium Fuel Research Facility (PFRF) in Oarai Research and Development Institute, Japan Atomic Energy Agency on June 6, 2017. During inspection work of storage container containing nuclear fuel materials, the PVC bag packaging in the storage container ruptured when a worker opened the lid in the hood, and a part of contents was spattered over the room. The cause of the increase of internal pressure of the storage container was gas generation by alpha radiolysis of the epoxy resin mixed with nuclear fuel materials. Opening inspection of about 70 similar containers stored in PFRF has been planned to confirm the condition of the contents and to stabilize the stored materials containing organic compounds. For safe and reliable open inspection of the storage containers with high internal pressure in the glove box, it is necessary to develop a pressure-resistant chamber in which the storage containers are opened and the contents are inspected under gastight condition. This report summarizes the concerns and countermeasures of the chamber design and the design results of the chamber.

Development of safety review method to cope with an aging degradation for the facilities using nuclear material

Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki; Omori, Tsuyoshi

Hozengaku, 13(2), p.115 - 125, 2014/07

http://ci.nii.ac.jp/naid/40020160893

In order to develop fuels and materials for fast reactors, five hot laboratories as a facility using nuclear materials for post irradiation examination (PIE) are now in operation at the Oarai Research and Development Centre of Japan Atomic Energy Agency. More than 30 years have passed since the first hot run of these facilities was started, and it has been indispensable to maintain the principal equipment for continuous safe operation. For application to preventive maintenance and the safe operation, a new safety review method that could be applied for these facilities was developed by modification of periodic safety review tools using for Japanese commercialized power reactors. Effective repair or replacement of equipment before malfunction have been performed and the priority for preventive maintenance could be appropriately determined for stable management of hot facility operations by the developed method.

Evaluation of fuel pin internal pressure by the 7 spectrum measurement

Katsuyama, Kozo; Fujishima, Tadatsune; Nagamine, Tsuyoshi; Matsumoto, Shinichiro

JNC TN9410 2003-006, 40 Pages, 2003/08

JNC-TN9410-2003-006.pdf:1.04MB

85Kr, which is one of gaseous nuclides generated in nuclear fissions, can be detected by gamma spectrum measurement. It is possible to calculate the fission gas amount discharged into the gas plenum of fuel pin and the inner pressure, based on the measurement data. In this study, the measurement and calculation were applied to the fuel pins irradiated in the experimental fast reactor JOY0. Then puncture testing was carried out for the applied fuel pins to measure fission gas amount and real inner pressure. As a result, it was confirmed that that calculated data were appropriate in general, compared with those gained by puncture testing. (1)The error of inner pressure calculated on the basis of gamma spectrum measurement is less than 25%, compared with the puncture test results. (2)As the result of this method applied to the fuels irradiation test rig (No.PFB090), the highest pressure was calculated in one of fuel pins loaded into N0.5 compartment, which burn-up was over 110 GWd/t. The pressure was about 50 Kg/cm2. This value was sufficiently less than that used in the fuel design.

Development of safety review method for hot laboratories, 2; Operation experiences and safety review of hot laboratories

Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki; Amagai, Tomio; Omori, Tsuyoshi

no journal, , 

no abstracts in English

Activity of safety review for the facilities using nuclear material, 2; Safety review results and maintenance experiences for hot laboratories

Amagai, Tomio; Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki; Omori, Tsuyoshi

no journal, , 

In the site of O-arai research and development center of Japan Atomic Energy Agency (JAEA), five hot laboratories for post-irradiation examination and development of plutonium fuels are operated more than 30 years. A safety review method for preventive maintenance on these hot laboratories includes test facilities and devices are established in 2003. After that, the safety review of these facilities and devices are done and taken the necessary maintenance based on the results in each year. In 2008, 372 test facilities and devices in these hot laboratories were checked and reviewed by this method. As a results of the safety review, repair issues of 38 facilities of above 372 facilities were resolved. This report shows the review results and maintenance experiences based on the results.

Activity of safety review for the facilities using nuclear material and improvement in the future

Fujishima, Tadatsune; Omori, Tsuyoshi

no journal, , 

no abstracts in English

Development of safety review method to cope with an aging degradation for the facilities using nuclear material, 2; Risk assessment flow of equipments

Tamaoki, Yuichi; Isozaki, Ryosuke; Suzuki, Ryuta; Akada, Masataka; Sawahata, Satoshi; Yonezawa, Ryoma; Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki

no journal, , 

no abstracts in English

Development of risk assessment method to cope with an aging degradation for the facilities using nuclear material, 2; Examination of risk assessment method in aging risk assessment

Sawahata, Satoshi; Tamaoki, Yuichi; Isozaki, Ryosuke; Suzuki, Ryuta; Akada, Masataka; Suzuki, Hisashi; Yonezawa, Ryoma; Fujishima, Tadatsune; Mizukoshi, Yasutaka; Sakamoto, Naoki

no journal, , 

no abstracts in English