A RECENT series of small leaks in a spent-fuel pool at a nuclear power plant near San Clemente, Calif., poses a potential safety hazard, claims a staff engineer at the plant.
The leaks, over time, may have generated a plume of radioactive water that could seep toward a popular surfers beach 170 feet away, according to the engineer and We the People, Inc., a whistleblower-protection organization based in Rowley, Mass.
Or, says the engineer, a 30-year-old rubber liner around of the spent-fuel containment pool may be allowing sea water in. The salt water could then seep through the concrete walls and corrode the pool's stainless-steel inner liner.
Southern California Edison's San Onofre Nuclear Generating Station consists of three reactors. The pool in question is part of Unit 1, which was shut down permanently in 1992 after nearly 25 years in operation. The pool has a history of leaks dating back to 1986.
Unit 1 was closed after the state Public Utilities Commission denied the utility a rate increase to cover $125 million in repairs.
Southern California Edison and Nuclear Regulatory Commission (NRC) inspectors say leakage from the pool at San Onofre 1 poses no immediate safety threat.
''We've alerted the NRC's Inspector General to what we have learned,'' says Stephen Comley, director of We the People, Inc.
The uncertainty over the origin of the water appearing in the pool's leak detection system is also found in the results of a December 1994 NRC report as well as in the utility's written response to the NRC inspection, submitted to the agency last month.
Not the first leaks
These leaks are not the first detected at a nuclear plant and they highlight concerns at other nuclear facilities surrounding spent-fuel pools, which were never designed for long-term storage of high-level radioactive waste.
The federal government's inability to move quickly on building either an interim or permanent high-level waste repository has left utilities with the prospect of holding onto the hot fuel far longer than anticipated.
In November of 1992, for example, two nuclear engineers working at Pennsylvania Power and Light Company's Susquehanna plant complained to the NRC that flaws in the design of the pools, which sit inside the reactor containment buildings, and inadequate safety procedures could lead to a meltdown under certain accident scenarios that the plant was designed to handle.
Since then, the plant has modified the spent-fuel pool system, ''significantly reducing the risk,'' says David Lochbaum, one of the two engineers who filed the complaint. But, he adds, ''We see the problem as applicable to most, if not all, boiling-water reactors.'' Some 35 such reactors are in use in the US, he says.
Safety concerns also extend to units that have been permanently shut down.
In January 1994, workers at Commonwealth Edison's Dresden 1 plant in Morris, Ill., discovered 55,000 gallons of water in the containment building's basement. Dresden 1, a boiling-water reactor, had been shut down since October 1978.
After investigating the incident, the NRC issued a ''generic letter'' last April to utilities holding licenses for eight closed units, including San Onofre 1. According to the NRC's letter, the water in Dresden 1's basement came from a pipe that had burst in freezing weather; the containment building was unheated. Although the water feed system to the fuel pool had not been damaged, the letter added that ''the lack of heating inside the containment under more severe weather conditions could potentially have resulted in the freezing and rupture'' of a tube that would have ''drained the SFP to several feet below the top of the stored fuel assemblies.'' If that were to occur, it concluded, employees would have been exposed to intense radiation. In addition, the letter noted the lack of a leak detection system and cracks in the unlined spent-fuel pool, which ''indicate the potential for pool leakage.''
The letter also cited interviews with workers at the Dresden site, which also includes two operating reactors, ''that showed, in part, the weaknesses identified were based on an incorrect belief that Dresden 1 could not cause a serious safety problem because it was permanently shut down.''
The letter required all the utilities receiving it to take several actions, including inspections to verify the adequacy of spent-fuel pool containment and other systems.
Last October, the NRC conducted a follow-up inspection at San Onofre 1. It found the plant's efforts to monitor conditions in Unit 1's pool were '''reasonable.''
But the report also noted the pool's history of leaks, dating back to 1986, when water from the pool seeped to the ground outside. According to the information supplied by the staff engineer, the utility had to remove contaminated soil at a depth of from 5 to 10 feet that came to within 85 feet of the sea wall separating the power plant from the beach.
Eyedrop worth of water
Last March, according to the NRC, detectors at the facility began to show a slow increase in leaks. Paul Klein, a utility spokesman, says that the 450,000 gallon pool is leaking at a rate equivalent to an eyedrop's worth of water a minute.
''None of it is leaking to the ground,'' he adds. In addition, the utility notes that the systems designed to handle leaks and to maintain the pool's water level are more than adequate to handle the current water-loss rates.
Yet both the NRC and utility concede that chemical analyses have failed to solve the riddle of the water's origin, although the utility maintains it is coming from inside the pool through a pinhole leak in the steel liner.
''No one really knows,'' the engineer said in an interview. He also is concerned about the waterproof membrane outside the pool, which never underwent environmental qualification tests. ''There was no quality assurance program when it was installed,'' he says.