Stabilization treatment of nuclear fuel material contained with organic matter

Senzaki, Tatsuya; Arai, Yoichi; Yano, Kimihiko; Sato, Daisuke; Tada, Kohei; Ogi, Hiromichi*; Kawanobe, Takayuki*; Ono, Shimpei; Nakamura, Masahiro; Kitawaki, Shinichi; et al.

JAEA-Testing 2022-001, 28 Pages, 2022/05

JAEA-Testing-2022-001.pdf:2.33MB

In preparation for the decommissioning of Laboratory B of the Nuclear Fuel Cycle Engineering Laboratory, the nuclear fuel material that had been stored in the glove box for a long time was moved to the Chemical Processing Facility (CPF). This nuclear fuel material was stored with sealed by a polyvinyl chloride (PVC) bag in the storage. Since it was confirmed that the PVC bag swelled during storage, it seems that any gas was generated by radiolysis of the some components contained in the nuclear fuel material. In order to avoid breakage of the PVC bag and keep it safety for long time, we began the study on the stabilization treatment of the nuclear fuel material. First, in order to clarify the properties of nuclear fuel material, radioactivity analysis, component analysis, and thermal analysis were carried out. From the results of thermal analysis, the existence of organic matter was clarified. Then, ion exchange resin with similar thermal characteristics was selected and the thermal decomposition conditions were investigated. From the results of these analyzes and examinations, the conditions for thermal decomposition of the nuclear fuel material contained with organic matter was established. Performing a heat treatment of a small amount of nuclear fuel material in order to confirm the safety, after which the treatment amount was scaled up. It was confirmed by the weight change after the heat treatment that the nuclear fuel material contained with organic matter was completely decomposed.

Development of gamma camera for survey of contamination distribution; Performance demonstration of gamma camera based on survey of contamination on operating floor of the Fukushima Daiichi Nuclear Power Plant Unit 2 reactor building by -eyeII

Kanayama, Fumihiko; Okada, Takashi; Fukushima, Mineo; Yoshimoto, Katsunobu*; Hanyu, Toshinori; Kawanobe, Takayuki

JAEA-Technology 2013-049, 60 Pages, 2014/03

JAEA-Technology-2013-049.pdf:25.84MB

For planning of removing fuels and debris from the Unit 2 reactor building, TEPCO has already started to measure dose rate over the floor by remotely operated vehicle. Because the measured data were widely distributed in the range of several decades to one thousand mSv/h, it is necessary for TEPCO to survey of contamination distribution on operation floor 2 for more detail planning. JAEA estimated sensitivity of developed gamma camera system named "-eye II" in consistency with actual radiation condition, and carried a demonstration experiment at Fukushima Daiichi N.P.P. to confirm a strength of jamming by back ground dose. Then, JAEA surveyed contamination distribution of operating floor using -eye II. At the result of survey, it was found that, - main radiation source in survey area was located on upper reactor well, - western floor in survey area was lower the margin of capacity of -eye II, -there was a highly contaminated spot on the floor near the opened BOP.

Measurement of contamination distribution for operating floor of the Fukushima Daiichi Unit 2 reactor building by camera, 3; Measurement and analysis

Fukushima, Mineo; Okada, Takashi; Kanayama, Fumihiko; Yoshimoto, Katsunobu; Hanyu, Toshinori; Kawanobe, Takayuki; Takahashi, Yoshiaki*; Oikawa, Kageharu*; Matsumoto, Yasuhiro*; Kishi, Kazuyoshi*; et al.

no journal, , 

Contamination distribution for operating floor of the Fukushima Daiichi Nuclear Power Plant was measured from opened blow out panel using viewer "-eyeII" developed by JAEA. It is obtained that one of the main contaminated area is on the reactor well and contamination level of the surface of west side floor is lower than lower limit level of detector.