Manufacture of substitutive assemblies for MONJU reactor decommissioning

Sakakibara, Hiroshi; Aoki, Nobuhiro; Muto, Masahiro; Otabe, Jun; Takahashi, Kenji*; Fujita, Naoyuki*; Hiyama, Kazuhiko*; Suzuki, Hirokazu*; Kamogawa, Toshiyuki*; Yokosuka, Toru*; et al.

JAEA-Technology 2020-020, 73 Pages, 2021/03

JAEA-Technology-2020-020.pdf:8.26MB

The decommissioning is currently in progress at the prototype fast breeder reactor Monju. Fuel assemblies will be taken out of its core for the first step of the great task. Fuel assemblies stand on their own spike plugged into a socket on the core support plate and support with adjacent assemblies through their housing pads each other, resulting in steady core structure. For this reason, some substitutive assemblies are necessary for the purpose of discharging the fuel assemblies of the core. Monju side commissioned, therefore, Plutonium Fuel Development Center to manufacture the substitutive assemblies and the Center accepted it. This report gives descriptions of design, manufacture, and shipment in regard to the substitutive assemblies.

Study on thermal influence of MA-containing MOX fuel characteristics on fuel performance

Kamei, Miho; Ozawa, Takayuki

no journal, , 

The future fast reactor (FR) cycle system to reduce radioactive waste volume by recycling Pu and minor actinides (MA), and it is important to evaluate the influence of high Pu content and MA content on oxide fuel performance. In this study, we investigated the influence of fuel characteristics on power-to-melt (PTM) from a viewpoint to prevent fuel melting. As a result, PTM of FR oxide fuel with high Pu content and MA content would be affected by fuel properties due to fuel composition, but it revealed that a correlation between fuel specifications and PTM in MA-containing MOX fuel would be similar to that in MOX fuel, and it can be mentioned that thermal performance of MA-containing MOX fuel would be secured to be equal to that of conventional MOX fuels by providing suitable fuel specifications up to MA content of 5 wt.%.

Study on forming condition of rim structure and the effect on integrity in a fast reactor fuel

Naganuma, Masayuki; Kamei, Miho; Maeda, Koji

no journal, , 

In the LWR fuel irradiated up to high burn-up, the obscure structure called "rim structure" is known to be formed and affect the integrity. The structure has been observed in the high burn-up fuel irradiated in the experimental fast reactor "Joyo", too. Thus, the fuel behavior analyses were conducted for the post irradiation examinations results by using the analysis code, and the forming conditions in the FR fuel were evaluated. As a result, it was found that there was difference in the forming condition between LWR and FR fuels according to the difference of irradiation behaviors between the two. Then, the effects of forming rim structure on FR fuel integrity were investigated and confirmed to be benign.