SAVANNAH RIVER

The nuclear reservation, near Aiken, S.C., has three active production reactors dating from the early 1950s. All are low-pressure, heavy-water cooled and moderated, and are rated at 2,800 megawatts thermal (roughly equivalent to an 800-megawatt power plant). The K and P reactors are used to produce tritium; the L reactor produces weapons-grade plutonium.

HANFORD

The Washington state nuclear reservation has one massive production reactor, the N reactor, which began operation in 1963. It is a pressurized, light-water cooled, graphite-moderated reactor, rated at 4,000 megawatts thermal (roughly equivalent to a 1,000-megawatt power plant). The reactor produces weapons-grade plutonium and steam for electric turbines. The reactor was shut down in January for safety modifications, but fuel reportedly has been loaded in preparation for a restart.

AMONG THE REPORT'S MAIN FINDINGS:

"The level of uncertainty about how long the production reactors can be safely operated is high . . . . The production reactors all display symptoms of acute aging that could affect safety and are likely to limit the useful lives of these reactors."

The most acute aging problem at Savannah River is stress corrosion cracking of the steel piping system and reactor tanks. "Cracks may be susceptible to unstable growth that could lead to catastrophic rupture of the coolant system."

At Hanford, the 1,700-ton graphite core is expanding, placing stress on the process and cooling tubes that run through it. The tubes, embrittled by radiation, are already vulnerable to cracking. The expansion also is distorting the channels used to insert control rods to shut down the reactor and the channels that would be used to insert boron carbide balls to quench the reactor in an emergency.

The Energy Department "has not clearly articulated, documented and implemented a safety objective for the operation of its production reactors."

"Off-site planning and preparedness . . . do not appear to be on a par with those of localities surrounding a commercial reactor."