Reactor Start-Up to Be OKd Despite Discovery of Broken Bolts

A spokesman for the Nuclear Regulatory Commission said Wednesday that there is no danger in restarting a reactor at the San Onofre nuclear power plant, despite the discovery of three broken bolts in the supports that hold up its “thermal shield.”

Greg Cook, public affairs officer for the NRC’s Western office, said the NRC is prepared to allow the start-up of reactor unit No. 1 if Southern California Edison submits written documents agreeing to conditions worked out in a meeting between the utility and the NRC Monday.

“With those conditions in place, staff is confident that the reactor will be safe to operate,” Cook said.

However, Cook characterized statements by an Edison spokesman that the NRC already has approved the start-up as “slightly premature.” Edison spokesman Lew Phelps said Tuesday that “all safety issues have been resolved, and we would not consider restarting the plant if that were not the case.”

The San Diego City Council, reacting to news accounts of the damaged bolts, approved an emergency resolution Tuesday urging the NRC not to permit the start-up of the reactor “until all questions regarding its safety have been been resolved.”

‘Worst-Case Scenario’

The council sent telegrams to Edison and San Diego Gas & Electric, co-owners of the San Onofre plant, and urged Rep. Jim Bates (D-San Diego) to intervene with the NRC to prevent the start-up of the reactor.

The resolution, written by Mayor Maureen O’Connor’s staff, asserts that “in a worst-case scenario (envisioned by NRC staff)” the broken bolts “could cause the shield to drop to the bottom of the reactor, affecting the flow of cooling water around the reactor core itself.”

Cook said, however, that, in a “worst conceivable scenario,” the thermal shield could drop just 11 inches, causing “an extremely minor difference in the way water enters the core. It wouldn’t be a major enough difference to be detectable.”

Three broken bolts have been discovered among the 36 that are connected to six supports that hold up the thermal shield, Cook said. The shield protects the pressure vessel surrounding the reactor core from radiation that, over time, makes the vessel more brittle.

Cook said it is “almost certain” that some of the other 22-year-old bolts in the reactor are “degraded” and “cracked.” But, if Edison submits written acceptance of the three conditions, the NRC is prepared to allow start-up of the reactor, he said. The reactor is capable of producing enough electricity to serve 400,000 homes.

Edison must agree to increased monitoring of the vibrations affecting the thermal shield and a special June, 1990, inspection of the supports and bolts, Cook said. It also must negotiate how the special inspection will be conducted, he said.