General Electric Co. has defended its Mark 1 reactor—the design at the crippled Japanese complex—as a reliable industry workhorse. Tom Cochran, a nuclear physicist and senior scientist with the Natural Resources Defense Council calls the design "demonstrably deficient." He says "the diesel generators are in the basement and spent fuel is in the attic. It should have been the other way around."
Pietrangelo said the inspections would go beyond the scope of regular safety checks at the plant. The companies will verify that plant operators could safely shut down reactors if there were a total loss of electric power; that crucial emergency equipment and systems could survive earthquakes, fires or floods, and that emergency personnel were properly qualified and trained, said Pietrangelo, speaking on behalf the industry's chief nuclear officers.
NRC requires nuclear plant operators to show that if hit with a single, or series of "worst case" scenarios, such as an earthquake and simultaneous rupture of the pipe delivering cooling water to the reactor, that the plant can be shut down safely without core damage. That is the standard, day-to-day requirement, he said. "We're going beyond that in this initial look," Pietrangelo said.
He said he did not think companies will report results of the inspections separately to NRC but, like all operational information, the findings will be available to NRC inspectors.
A power loss at a U.S. reactor
The UCS report focuses on the effectiveness of the resident NRC inspectors stationed at the U.S. plants. The cases included in the report show both diligent attention by NRC, and complacency that allowed operators to sweep problems under the rug.
One of the incidents covered in the UCS report was an electrical fire at Progress Energy's H.B. Robinson nuclear plant near Hartsville, S.C., on March 28 last year.
The incident began with a short-circuit on a major electrical cable, which caused a drop in power supplied to a large pump circulating water through the reactor. The reactor shut down automatically, but the incident damaged the main power transformer connecting the plant to the outside electrical grid, and other events left about half of the plant's equipment without power.
That power loss caused a sequence of problems with valves affecting the control of the reactor's temperature, but operators failed to notice the problems for nearly an hour, the report said.
After four hours, operators tried to restore power to the circuit where the short had occurred but did not check first to see that that problem had been solved. It had not been, and when the line was re-energized, another fire resulted. The failed cable, installed in 1986, did not meet design parameters, the report said.
Six months later, another series of equipment failures and operator errors caused another reactor shutdown at the plant. One of the equipment issues had been known to the operators since 2003 but had not been fixed, the report said. In this case, the operators relied on an auxiliary water supply system to provide cooling to the reactor by first disabling safety controls. The goal was to avoid a critical NRC review, the report said.
NRC issued a notice yesterday saying that while it concluded the plant had operated safely last year, commission staff will be stepping up inspections and oversight based on problems surrounding the reactor shutdowns.
Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500