3 Violations at San Onofre Cited by NRC

Three violations of federal regulations apparently led to a November accident that threatened the stability of a safety-related water coolant system at the San Onofre nuclear power plant, a Nuclear Regulatory Commission investigation has found.

If confirmed by high-ranking commission officials, the violations could lead to fines against Southern California Edison Co., the utility that operates the seaside plant in North San Diego County.

The report, completed May 16, also will form the basis for any commission decision on Edison’s request to restart San Onofre’s unit 1, which was shut down after the Nov. 21 accident and cannot be restarted without the NRC’s permission.

The “apparent violations” cited in the NRC report involved the lack of an adequate program for detecting problems in safety-related equipment, an inadequate response when one key safety problem was detected and the failure to provide proper procedures for trouble-shooting electrical problems at the plant.

A top-ranking Edison official said Wednesday that the company would not dispute two of the report’s three findings. Ken Baskin, vice president for nuclear engineering, safety and licensing, said he differed with the NRC’s conclusions on the electrical problems that led to the accident.

Still, Baskin conceded that a key decision by plant operators to postpone visual inspection of a faulty valve was “a bad one.” But Baskin said the utility employees who made the decision did their best with the information they had at the time.

“Knowing what they knew at the time, the judgment wasn’t that bad,” Baskin said. “If I was making that decision, I don’t know if I would have made it any different.”

As it turned out, the suspect valve and four others like it all failed in November, creating conditions that made possible what is known as a “water hammer”--the over-pressurization of a 10-inch pipe and a resultant shock wave that cracked the pipe, damaged several pipe supports and released non-radioactive steam into the atmosphere.

The incident ended with no injuries, no release of radioactivity and no danger to the public.

The utility’s response to the valve problem in June, 1985--five months before the accident--was the basis for one of the apparent violations cited in the report.

During normal operation on June 24, plant employees heard a “loud rapping or metal tapping noise” in a valve in the auxiliary feedwater system, the report said. The feedwater system sends cool water to the steam generators, where it combines with hot water from the reactor core to produce the steam that turns the electricity-producing turbines.

The cause of the strange noise was investigated, and a plant committee concluded that the reactor could be safely operated. The internal probe also determined that a second valve could have failed, and a visual inspection of the valves was scheduled to be performed the next time the plant was shut down.

But by the time of the next outage, in August, the noises in the pipe had disappeared, and “no additional attention was paid to the valve,” according to the report.

The NRC now believes that the noises stopped because the valve had fallen apart and stopped working.

Baskin agrees, and he said plant operators put off the inspection because they believed that even if the one valve failed, the reactor could be operated safely. He said they never considered that all five valves might fail at the same time.

“In hindsight, that was obviously a bad call,” Baskin said.

Since then, the utility has installed three new valves and redesigned the ones that failed. Baskin said Edison has also checked the design of all other valves in the plant and reviewed reports of valve failures at other plants around the country.

Edison spokesman David Barron said Unit 1 could be restarted within a month if the NRC approves.