nuclear-news

Bolt failure found in 3 Salem reactor pumps Delawareonline Jeff Montgomery, The News Journal PSEG Nuclear workers have found there is a complete failure of all bolts securing water-pushing impellers in three of four Salem Unit 2 reactor coolant pumps, with investigations continuing inside the last unit.

The findings, released Monday, emerged after the discovery of broken parts in one of the big, water-moving units forced the company to delay a post-refueling restart last month.

Nuclear Regulatory Commission officials said Monday all retaining bolts were found to be “sheared or failed” in three of four 30-foot-tall reactor coolant pumps in Salem 2 in New Jersey. The pumps force water back into the reactor core after it circulates through systems that make non-radioactive, pressurized steam used to turn generators.

The 1,158-megawatt Unit 2 went offline and began a refueling outage April 13, with the shutdown extended when broken bolt-heads were found on eight of 20 fasteners that secure a bladed “turning vane” part inside one of the pumps. Subsequent examinations found all 20 bolts to be “sheared or failed” in three of the four pumps, which had to be shipped off-site for examination.

“Because the pumps are part of the reactor coolant system, they are part of a barrier against release of radioactive water, though that water would be captured inside the reactor containment building during an accident,” said Neil Sheehan, spokesman for the NRC’s regional office in King of Prussia, Pennsylvania…….

David Lochbaum, a nuclear power engineer and specialist for the Union of Concerned Scientists, said Monday that the pumps play a part in plant cooling but are not considered part of the plant’s safety system. Loss of bolts could become a safety problem if turbine blades, which spin at thousands of revolutions per minute, or other parts broke loose and penetrated the pump housing or moved into other parts of the cooling system.

“It sounds like they caught it early enough,” Lochbaum said, noting that severe problems would likely have created vibrations or wobbling that would have been detected by plant sensors. http://www.delawareonline.com/story/news/local/2014/06/09/bolt-failure-found-three-salem-unit-reactor-coolant-pumps/10245099/