Japanese steel components sufficiently strong, NRA says

Friday, 25 November 2016

 Japan's Nuclear Regulation Authority (NRA) has concluded that domestically produced nuclear power plant components are sufficiently strong for their intended purpose.

The country's 11 nuclear generating companies conducted investigations after anomalies were discovered in equipment manufactured at France's Le Creusot forge. That discovery raised concerns that forged steel components made by the Japan Casting & Forging Corporation (JCFC) for use at the Flamanville 3 EPR could contain similar anomalies.

According to the Japan Atomic Industrial Forum (JAIF), the NRA decided this week to accept the companies' findings that the JCFC-manufactured equipment in place at their plants was sufficiently strong. It said it was "unlikely that any of the products" used by the 11 companies in their plants "contained carbon concentrations higher than prescribed limits" for safety-related systems. The NRA thus concluded there was no possibility of "weaker-than-expected performance" of such products in any Japanese nuclear power plant.

The NRA found JCFC 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, the JAIF said. Increased levels of carbon in the steel used in large forged components, such as reactor pressure vessels and steam generators, can result in lower mechanical strength.

The regulator also came to the same conclusion for nuclear plant safety-related systems produced by other domestic manufacturers, including Japan Steel Works.

According to the power companies, JCFC manufactured vessel heads for 11 nuclear reactors at seven Japanese sites. No problems had been found at any of those reactors, JAIF said.

In June, French nuclear safety authority the ASN (Autorité de Sûreté Nucléaire) said it had identified 18 French nuclear power reactors whose steam generators could contain high carbon concentrations, including 12 equipped with channel heads manufactured by JCFC.

Researched and written
by World Nuclear News