nuclear-news

A series of defective products at a French MOX fuel plant Abnormal nuclear reaction at a nuclear power plant

September 3, 2022

A series of defective products have been found at the Mellox plant in southeastern France, which manufactures fuel for plutonium thermal power generation, in which plutonium is burned in nuclear power plants. In addition, an abnormal increase in nuclear reactions has also been observed at some nuclear power plants that are conducting plu-thermal power generation. What in the world is going on?

　The plant also manufactures fuel for the Japanese market. No problems have been found so far with the fuel for the Japanese market, but production has been delayed, and future product deliveries are now unpredictable.

　Plutonium is extracted from spent nuclear fuel from nuclear power plants through chemical processing (reprocessing). Plutonium is mixed with uranium in the case of pressurized-water nuclear power plants that conduct plutonium thermal power generation, and baked into pellets, cylindrical grains about 8 mm in diameter. This is called mixed uranium-plutonium oxide fuel (MOX fuel). In the case of a pressurized-water nuclear power plant that conducts plutonium thermal power generation, approximately 320 pellets are stacked inside fuel rods, and another 260 fuel rods are bundled together to form a fuel assembly (approximately 4.1 meters in height).

Highly Difficult Homogenization

　It is difficult to uniformly mix plutonium and uranium. According to ASN data and other sources, “plutonium spots,” dense clumps of plutonium, were found in the fuel pellets produced at the MELOX plant. Plutonium spots were found in the fuel pellets manufactured at the MELOX plant.

　On the other hand, a phenomenon in which the amount of neutrons, which indicate a nuclear reaction, increases more than expected near the upper and lower ends of MOX fuel rods was confirmed at a French nuclear power plant conducting a plutonium thermal operation.

　According to ASN, the combination of this plutonium mass problem and the two anomalies of partially elevated nuclear reactions was predicted to “raise questions about the integrity of the fuel, depending on the circumstances of the accident.

　According to Chihiro Uesawa, 56, an engineering specialist at the NPO Nuclear Information and Data Center (Nakano Ward, Tokyo), concerns are that the fuel could melt or the tubes covering the fuel could break. When plutonium is used as fuel, it has been pointed out that there is a possibility of a localized increase in nuclear reactions. This has become apparent,” Uesawa said.

https://mainichi.jp/articles/20220831/k00/00m/040/238000c?fbclid=IwAR1mQYYAbxefVEt_eDl-y8N9DfIOlvhN-MSVKCbbWsgR7rmvCRI6gu8ZyEE

September 4, 2022 Posted by dunrenard | Japan | Defective products, France, Mox Fuel, Takahama NPP | Leave a comment