Japan’s Nuclear Regulation Authority (NRA) has said that it is “unlikely” that equipment forged at the Japan Casting and Forging Corporation (JCFC) and in use at Japan’s NPPs contains carbon concentrations higher than prescribed limits for safety-related systems. According to industry group, the Japan Atomic Industrial Forum (Jaif), NRA decided at a meeting on 22 November that there is no possibility of weaknesses in components made from JCFC steel at any domestic nuclear plant.

In 2014, an examination by France’s nuclear regulator, the Autorité de Sûreté Nucléaire (ASN), showed that steel used at the Flamanville-3 EPR under construction in northern France and manufactured at Areva’s Le Creusot forge facility was weaker than expected. Subsequent analysis by ASN indicated that steel from Le Creusot and JCFC might have had significant carbon concentrations that could cause weaknesses. Jaif said NRA had accepted assurances from Japan’s 11 nuclear utilities that all steel forged at JCFC and in use at their nuclear stations met required standards.

The NRA found that JCFC had sliced off those parts of its steel ingots containing high concentrations of carbon before using them to manufacture products. It therefore determined the products in question were sufficiently strong, Jaif said. NRA also came to the same conclusion for nuclear plant safety-related systems produced by other domestic manufacturers, including Japan Steel Works. The power companies said JCFC manufactured vessel heads for 11 nuclear reactors at seven Japanese sites. No problems had been found at any of those reactors, Jaif said.