Troubles Plague U.S. Nuclear Plant Akin to Chernobyl

An aging nuclear power plant near here that is strikingly similar to the failed Soviet Chernobyl facility has been troubled for years by equipment failures, poor workmanship and human errors that have compromised vital safety systems, according to official documents.

Department of Energy records on the Hanford nuclear plant filed here report that nuts, bolts, pieces of broken equipment and even old flashlight parts have been flushed through the reactor cooling system, damaging internal parts. Valves and doors that are integral to the safety system have failed, either through human error or equipment malfunction.

Unscheduled Shutdowns

Since October of 1982, there have been 42 unscheduled shutdowns of the reactor--each lasting from one to two days and almost all of them for safety reasons. This year alone, the reactor has been shut down six times because the cooling water was contaminated by leaking radioactive fuel.

Plant officials blame the recent shutdowns on leaks from tiny punctures in the protective zirconium that encases the plant’s uranium fuel. They believe that the punctures may be caused by broken parts rattling through the reactor.

Now, the graphite core that is at the heart of the reactor is warping and the metal tubes that pass through the core are becoming bowed and brittle, making it increasingly difficult to insert and retrieve uranium fuel rods as well as the control rods that are essential in shutting down the nuclear reaction.

Department of Energy officials say that unless the tubes are replaced and the graphite core restored within the next few years, the production life of the reactor cannot be expected to last beyond the mid-1990s.

Despite such problems, the reactor here never has had a major accident and there never has been a significant release of radioactivity into the atmosphere, according to records and DOE officials.

Under New Scrutiny

Nonetheless, because of its similarity to the Chernobyl plant, the Hanford plant is under new scrutiny. The Energy Department, which owns the plant, has ordered two safety investigations of the reactor and invited the National Academy of Sciences to conduct a third. A hearing on the Hanford plant is scheduled Monday in Portland, Ore., by a House Interior Committee subcommittee chaired by Rep. James Weaver (D-Ore.)

Environmentalists in the Northwest have focused their energy on closing the plant, rallying under the cry of “shut down before a meltdown.”

The Hanford plant, designated by the Department of Energy as the N reactor, is one of the nation’s oldest operating plutonium production reactors. Commissioned on Dec. 31, 1963, it accounts for an estimated 20% of the nation’s plutonium production for nuclear weapons. In 1966, it was modified to also generate 860 megawatts of electricity for the Washington Public Power Supply System, which wholesales the power to other distributors.

Like the Chernobyl plant, the reactor here has a graphite core and no containment dome, despite early warnings in then-secret government documents that the accidental release of the reactor’s fission products would be “so catastrophic that adequate containment must be provided.”

Operators of the plant say that a repeat of the Chernobyl disaster could not happen here because of the plant’s numerous and redundant safety systems.

Indeed, one official called the reactor “meltdown proof.”

Meltdown Unlikely

“We have yet to identify any mechanism, credible or incredible, which would allow a (graphite fire) to occur . . . or result in a full core meltdown,” said Michael J. Lawrence, DOE operations manager at Hanford.

Engineers who run the plant today blame many of the past problems on an attitude that placed production values above safety. That attitude changed after the near-disaster at Three Mile Island in Pennsylvania in 1979, they said.

“During the early ‘70s, the mission was to produce plutonium; very little money was provided for the reactor in terms of maintenance of systems,” said Thomas E. Dabrowski, director of reactor engineering for UNC Nuclear Industries, which operates the plant under contract to the DOE.

Today, things are different, officials said. “It is better, safer and operated more efficiently than the day it started up,” Lawrence said.

Government records show that safety issues here have been a concern for decades, beginning with the decision not to build a containment dome that could withstand the kind of explosion that ripped open the Chernobyl reactor building.

Result ‘Catastrophic’

Secret government reports from the 1950s and 1960s, since declassified, warned that the accidental release of the Hanford reactor’s fission products would be “catastrophic.”

Those reports repeatedly questioned whether anything short of full containment would be adequate, but conceded at one point that the decision to build the plant without it would result in “lower cost.”

“Escape from the building of a large fraction of the fission products accumulated in a reactor of this power level would be so catastrophic that adequate containment must be provided,” said one secret report in 1958.

The reports were prepared by the Advisory Committee on Reactor Safeguards, which was set up by federal law to advise the government on plant safety. The committee, formerly an advisory committee to the defunct Atomic Energy Commission and now an adviser to the Nuclear Regulatory Commission, stopped examining government-owned reactors in the early 1970s and now reviews safety only at commercial plants.

In 1960, the committee reversed itself and, with some caveats, agreed that the Hanford plant would not require a containment building. Committee members concluded that the sheer size of the 570-square-mile Hanford reservation provided an adequate safety margin for the general public. The nearest town to the plant is Richland, 35 miles away.

‘Inherent Safety’

The advisory committee also said that the Hanford reactor’s “inherent safety” was an improvement on older plants and thus would “not greatly change the overall safety picture at Hanford.”

However, the committee also urged that the Hanford plant be required to meet the same standards the federal government required of commercial plants--a recommendation that would be repeated in the years ahead by the General Accounting Office and two internal Department of Energy investigations.

To this day, DOE reactors are not licensed by the Nuclear Regulatory Commission, are not subject to its regulations, and do not always meet the same standards that commercial reactors are required to meet.

The government’s continued insistence that there is no danger of a Chernobyl-type accident at Hanford is perplexing to one highly respected expert on nuclear safety, who agreed to discuss Hanford only on the grounds that his name not be used.

He noted that both Hanford and Chernobyl encase their uranium fuel in zirconium cladding, and both use graphite as a moderator to sustain the chain reaction.

Can Generate Gases

“In either case, they have a fuel cladding that can interact with water and form hydrogen,” said the expert, who is a nuclear engineer and a member of the Advisory Committee on Reactor Safeguards. “Both have a graphite core that when heated can make water gas (a combination of hydrogen and carbon monoxide.) Both have characteristics that can generate combustable gases.”

Soviet leader Mikhail S. Gorbachev confirmed last Wednesday what many U.S. experts had already concluded, that the explosion that ripped open the building that housed Chernobyl was caused by hydrogen that was not supposed to have been there.

During such an explosion, other components of the plant’s safety system were undoubtedly damaged, according to American engineers.

The worldwide consequences of the Chernobyl accident might have been reduced had the Soviets built a containment dome over the reactor. Instead, like the Hanford reactor, the Soviet plant was enclosed in a “confinement” building.

Unlike the familiar reinforced concrete containment domes at commercial nuclear power plants such as the one at San Onofre, confinement buildings are not designed to withstand high internal pressures or an explosion.

No Radioactivity Leak

In the event of a break in the reactor’s primary cooling system, the first surge of steam would be released directly into the air through six-foot vents on the roof to avoid a buildup of pressure inside the building. Officials said that first release of steam would not include radioactive materials.

Experts calculate that highly dangerous fission products would not escape the damaged reactor for at least 150 seconds. By that time, automatic valves in the roof vents are supposed to have closed, sealing the building. Any further increase in pressure from escaping steam and other gases would be vented into the air through carbon filters, which are supposed to trap radioactive particles.

From the beginning, however, there have been serious concerns about this safety system.

In a 1960 letter to the Atomic Energy Commission, Leslie Silverman, chairman of the Advisory Committee on Reactor Safeguards, suggested that a valve malfunction in one or more of the steam vents in the reactor building would leave “the building open to the atmosphere during evolution of fission products.”

That concern was to prove disturbingly near the mark 22 years later.

Improper Repairs

On Aug. 4, 1982, workers discovered that a key valve intended to prevent the escape of radioactivity into the environment had been improperly repaired. A part had been installed backwards. Had there been a reactor accident, the valve could have closed too slowly to seal a six-foot-diameter vent directly above the reactor to prevent the escape of highly radioactive particles into the atmosphere.

Officials said a second, backup valve in the same vent would have closed in time, however, and that the faulty repair job would not have had “nuclear safety implications.”

There have been other momentary breaches of confinement, according to DOE reports.

In September of 1984, two engineers were trapped briefly inside the reactor building because both doors jammed on an air lock designed to permit workers to enter the building while the plant is running without breaching the “confinement integrity.”

The men got out, but the confinement was breached twice during the process, for 30 seconds and 45 seconds, when both doors were left open.

Investigators determined that the latch had malfunctioned on the inner door, but no one was sure what caused the outer door to jam, according to the report.

Workers’ Reliability

Problems with valves, doors and vents worry nuclear engineers because a nuclear power plant depends on the reliable performance of scores of mundane parts. Thus in the end it is the plumbers and welders and electricians and various laborers as much as the nuclear engineers who determine whether the system will work.

Hanford, like all nuclear plants, consists largely of a complex webbing of pipes that remove heat from the reactor. The heat turns water into steam to run turbines and generate electricity. In nearly all nuclear plants, the heat is removed from the reactor by water, which also serves to cool the reactor core.

Yet the Hanford reactor has experienced repeated problems with a series of valves designed to allow a special coolant to flow through the reactor during an emergency.

If enough of the valves fail, emergency cooling water cannot be pumped through the fuel core to quench the chain reaction and keep the reactor from overheating. That is the last ditch means of preventing a meltdown.

Although there are redundancies in the safety systems, many of those parts, which must be kept in near-perfect working condition, must sit idle for months and yet function immediately during an emergency.

Not Close to Chernobyl

Hanford has never reported a malfunction that came even close to rivaling the problems at Chernobyl, but over the years the plant has experienced nagging problems that could have proved serious during an emergency.

While the plant was shut down for routine maintenance in 1980, workers discovered a wide range of problems over a four-month period with valves that would be essential during an emergency cooling operation. In some cases the valves were not working at all, and in other cases their performance was questionable.

The reactor has eight valves, called V-4 valves, designed to open so that boron and water can be pumped through the reactor during an emergency cooling operation. The boron absorbs neutrons emitted by splitting atoms. That stops the neutrons from splitting other atoms, thus ending the chain reaction.

At least four of the valves--two on each side of the reactor--must work to ensure emergency cooling, according to one official report.

Significant problems were found with seven of the eight valves, including electrical grounding that could have left some of them inoperable. The report concluded that the grounding was caused by a design flaw that allowed moisture to accumulate in electrical solenoids that operate the valves.

Faulty Installation

Other problems resulted from leaking high-pressure air lines, damaged and worn-out parts and defective electrical connections. In some cases, workers had installed the valves incorrectly. They also had trouble reinstalling some of the valves because electrical wiring removed for repair had not been labeled for reconnection and the chart showing which wires went where was inaccurate, the report said.

Late last year, an equipment maintenance test made during a reactor shutdown uncovered part of an 18-inch valve from the primary cooling system lying in the bottom of a pipe. Studs, nuts and nut retainers that normally secure the valve hinge plate to the valve body were missing and apparently had been flushed through the reactor’s primary cooling system.

One of the steam generators--which lowers the temperature of the primary cooling water after it passes through the reactor core--had been badly damaged, apparently by constant battering by broken parts. In addition, old flashlight parts were found in the cooling system, apparently dropped by workers much earlier.

A review of the incident by the Department of Energy applauded UNC Nuclear Industries for the “exemplary” manner in which it discovered and solved the problems and concluded that the broken valve did not pose a safety hazard.

‘Considerable Doubt’

But, the department added, “The valve problem casts considerable doubt upon the quality of past performance in these areas at N reactor.”

In an interview, Dabrowski, UNC’s director of reactor engineering, said, “I would say the past performance is not up to our standards today.”

Dabrowski said that instructions provided by the valve manufacturer for tightening the valve bolts were inadequate. The bolts were not tightened enough and eventually fell off and were carried through the primary cooling system.

A worsening problem at the plant is the warping and occasional fracturing of the reactor’s 1,800-ton graphite core, which has resulted in the bowing of tubes or channels that run through it. As the tubes bend, it becomes increasingly difficult to slide in both fuel rods and control rods.

The graphite is used to moderate the nuclear reaction by slowing neutrons emitted by atom-splitting actions so that they will be more likely to split other atoms, thus sustaining the chain reaction. The bombardment is causing the graphite to expand, thus forcing it to deform, sag and, in some cases, break.

Graphite Block Breaks

The distortion was great enough in 1974 to result in a failure of a cooling tube when a graphite block broke, according to a safety analysis report prepared by the DOE.

DOE spokesman Tom Bauman said precise costs for replacing the graphite core have not been developed. But, he said, it would run “several hundred million dollars.” He said he did not anticipate any replacement work before 1990.

Despite such problems, those responsible for running the Hanford plant insist that it poses no threat to public safety.

Dabrowski said: “We can’t leave any legacy for failure in the future. . . . I know those check valves will never fail again in the future. In addition, I know that all of the other components in the primary and connecting cooling systems . . . aren’t going to fail.”

UNC Nuclear Industries President Nicholas C. Kaufman added: “I think the risks are minuscule in terms of people in the surrounding area. I live and work in this town and raise my family here.

“This gets real personal when you’re talking about safety.”

NUCLEAR PLANTS WITH NO CONTAINMENT

(1) HANFORD NUCLEAR RESERVATION

No. of Reactors: 1

First Operated: 1963

Reactor Type: Graphite moderated, light-water cooled

Purpose: Electricity and plutonium production

Capacity in Megawatts Thermal: 4,000

Plant Operator*: UNC Nuclear Industries, a UNC Resources Company

Nearest Town: Richland, Wash, pop. 30,000, 35 miles away

(2) IDAHO NATIONAL ENGINEERING LAB

No. of Reactors: 1

First Operated: 1968

Reactor Type: Low pressure, light-water cooled and moderated

Purpose: Research

Capacity in Megawatts Thermal: 250

Plant Operator*: EG&G; Idaho

Nearest Town: Atomic City, Idaho, pop. 31, 12 miles away

(3) OAK RIDGE NATIONAL LABORATORY

No. of Reactors: 2 (Oak Ridge Research Reactor and the High Flux Isotope Reactor)

RESEARCH REACTOR

First Operated: 1958

Reactor Type: Low-pressure, light- water cooled and moderated

Purpose: Research

Capacity in Megawatts Thermal: 30

Plant Operator*: Martin-Marietta Energy Systems Inc.

Nearest Town: Oak Ridge, Tenn., pop. 28,000, 4 miles away

HIGH FLUX ISOTOPE REACTOR:

First Operated: 1966

Reactor Type: Beryllium-reflected, light-water-cooled, light-water moderated

Purpose: Production of manmade elements for research

Capacity in Megawatts Thermal: 100

Plant Operator*: Martin Marietta Energy Systems Inc.

Nearest Town: Oak Ridge, Tenn., pop. 28,000, 4 miles away

(4) SAVANNAH RIVER PLANT

No. of Reactors: 4--three operating currently.

First Operated: 1953-1955

Reactor Type: heavy-water cooled and moderated, low pressure, low temperature

Purpose: Production of plutonium and tritium for nuclear weapons

Capacity in Megawatts Thermal: 2,500

Plant Operator*: E.I. du Pont de Nemours and Co.

Nearest Town: Jackson, S.C., pop. 2,000, 9 miles away

* Under contract to the U.S. Department of Energy .

SAFETY WOES AT HANFORD Officials at the aging N reactor power plant at Hanford, Wash., which like Chernobyl has a graphite core and no containment dome, anticipate safety problems in the reactor and now plan repairs.

The graphite is warping which could make it difficult to quickly insert control rods to stop a nuclear reaction. and the tubes through which control rods pass are becoming brittle.

Warping of the graphite could also hinder a redundant safety feature, dropping boron balls into the core from above to stop a nuclear reaction.

Among other safety worries: Valves in the critical cooling system have malfunctioned and other equipment has failed. Human errors and poor workmanship have compromised safety systems, including those intended to keep radioactivity from leaking into the air. Worn equipment is breaking, and pieces have been found floating loose in the reactor’s cooling system, where they have dammaged reactor equipment. MICHAEL HALL / Los Angeles Times