$70-Million Overhaul of Nuclear Reactor Nearly Done

WASHINGTON —  A $70-million program of safety improvements prompted by the Chernobyl accident in the Soviet Union is nearly complete at the United States’ largest plutonium production reactor for nuclear weapons, and the White House is expected to decide shortly whether the reactor facility should be reopened, federal officials said Friday.

Congressional sources said the Department of Energy, which operates the 25-year-old N reactor at the Hanford Nuclear Reservation in Washington state, favors mothballing it for budgetary reasons. That would affect about 3,300 of the 14,000 jobs at the weapons production complex and cut $150 million in operating costs from the Department of Energy budget next year.

Energy officials who asked not to be identified said the issue of whether to restart the reactor or mothball it is now before the Office of Management and Budget, which is expected to make a final decision before Feb. 18, the day President Reagan is to announce his proposed budget for fiscal 1989.

Need for Plutonium

Both congressional and Administration officials said the fate of the aging reactor will turn partly on the Defense Department’s current need for additional plutonium, the heavy fissionable metal that forms the explosive core of most nuclear weapons.

Although details of the plutonium stockpile are classified, two officials said the government has substantial reserves and that recycling of warheads that must be removed under the Intermediate Nuclear Forces treaty signed with the Soviet Union in December could further reduce the need for new plutonium production. The treaty allows both sides to keep the explosive parts of warheads, called the “physics package,” intact or to salvage the components for use in other weapons.

Sen. Mark O. Hatfield (R-Ore.) believes the Administration will shut the N reactor down, according to a staff assistant who said the senator called the facility a “memory.”

‘Decision Not Made’

However, Gretchen White, administrative assistant to Rep. Sid Morrison (R-Wash.), whose district includes the Hanford complex, insisted that a “decision has not been made,” although she said Secretary of Energy John S. Herrington has indicated he wants to close the facility. With the reactor’s overhaul nearly completed, White said, it would be reasonable to finish the job and restart the reactor for tests.

“Every scenario says the N reactor is to be available” for future plutonium production even if it is not reopened now, White said. “If it is to be available, it makes sense that you have a plant that is safe and reliable.”

A Department of Energy spokesman refused to comment on Herrington’s views.

The federal government has alternative sources of weapons-grade plutonium, chiefly the L reactor at its Savannah River production facility in South Carolina. But White noted that some experts remain concerned about safety problems at that reactor, too.

Controversy over the safety of the N reactor arose in 1986 because its design resembles that of the Chernobyl plant, which exploded during an unauthorized test that April, spewing radioactive fallout that was detected around the world. Both reactors were built of graphite, a form of carbon that moderates, or slows, the neutrons released by fissioning uranium fuel to sustain a chain reaction.

Chernobyl Explosion

At Chernobyl, a loss of cooling water in part of the reactor led to what engineers call a “positive void effect,” which allowed the fission chain reaction to race out of control and trigger a steam or hydrogen-gas explosion that shattered the reactor. Although U.S. experts said the N reactor is much less vulnerable to the void effect, its general similarity to the Chernobyl unit led the Department of Energy to shut it down in December, 1986, and begin a safety overhaul.

Karen Wheeless, a spokeswoman in the Department of Energy’s Richland, Wash., office, said the work is within two months of completion.

The overhaul has included installation of a system for purging explosive hydrogen gas that might result if cooling water leaked into contact with hot graphite. Emergency cooling and waste treatment systems have been upgraded and the pressure tubes carrying cooling water through the graphite have been examined and tested, Wheeless said.

However, the reactor still suffers a major problem that can be fixed only by rebuilding it. Over the years since President John F. Kennedy inaugurated the reactor in 1963, intense radiation has caused the graphite blocks that make up the reactor to swell. Although the swelling is thought to pose no immediate safety problem, with continued operation the slowly ballooning reactor will hit the top of its enclosure by the mid-1990s.

“When that happens, it means the end of the reactor’s usable life,” Wheeless said. “It can only be fixed by replacing the graphite, and there are no plans to do so now.”

Staff writer Larry Stammer contributed to this story from Los Angeles.