Monday Update on Japanese Nuclear plants

WHile the press has been fixated on the hydrogen explosion in Unit 3 at Fukusmima Daiichi, Unit 2 lost cooling today twice for approx 140 minutes due to issues with a pressure relief valve, which allowed reactor vessel pressure to increase, blocking the injection of saltwater. The core has been recovered. However, there has been a report of another explosion in the vicinity of the Unit 2 suppression pool. TEPCO reported that the suppression pool pressure dropped to ambient atmospheric pressure shortly following the explosion, indicating possible damage to the reactor’ pressure suppression system. This is serious. However, as long as TEPCO can keep the cores covered, any radiation releases can be minimized. The maximum measured dose rates around the reactors have risen to a peak of 330 millirem/ hr just prior to the second uncovery of the Unit 2 core. However dose rates continue to fluctuate.

At the Fukushima Daini site, offsite power has been restored to all Units and reactor water levels are stable. Normal Residual Heat Removal systems are being restored to cool the reactors to cold shutdown.