Cooling Accident at Rancho Seco Chills Nuclear Power Industry

An accident that seemed typical for the Rancho Seco nuclear power plant has become one of the worst headaches in the industry, leaving the plant’s restart uncertain, forcing rate hikes, and raising safety concerns elsewhere.

In the pre-dawn hours the day after Christmas, operators futilely fought to halt a rapid temperature drop in the nuclear reactor vessel amid a chorus of alarms that also warned--falsely--of both a fire and an earthquake. An operator collapsed from the stress.

Federal investigators said a power outage to control room instruments and employee errors allowed the steel vessel to cool 180 degrees in 24 minutes--well beyond the 100-degrees-per-hour limit designed to prevent cracking of a vessel, which could drain water that acts as a coolant and trigger a reactor meltdown.

The episode did not last long enough to fracture the vessel, but before it was over, two workers had been exposed to an apparently safe level of radiation and the plant had vented a reportedly harmless amount of radioactive steam into the air over Sacramento Valley pastures, about 25 miles southeast of the California capital.

One of Worst

The Nuclear Regulatory Commission has said the overcooling was one of the dozen worst problems suffered by U.S. plants last year and the most serious of the many woes that have plagued the 913-megawatt Rancho Seco plant since it was built 12 years ago at a cost of about $375 million.

Seven months after the overcooling, the Sacramento Municipal Utility District (SMUD) remains locked in a struggle to upgrade safety and employee training enough that the federal government will allow a restart by perhaps February, 14 months after the overcooling. The effort, together with lost electric revenue, is expected to cost the district about $100 million.

SMUD, the owner and operator of Rancho Seco, faces a federal fine of $300,000 to $1 million due to the accident.

Meanwhile, the deficit-ridden utility--one of the largest customer-owned utilities in the nation--must buy much of its electricity from outside agencies. As a result, the utility hiked rates nearly 10% in July, on the heels of two rate increases of about 30% last year. Other increases may follow.

The utility, which serves more than 380,000 customers, suffered a decrease in its bond rating due to the financial woes, which made borrowing money more expensive; and another utility, Pacific, Gas & Electric, is fighting to break a power-sharing agreement with SMUD because Rancho Seco isn’t producing any electricity to share.

Closure Effort

A citizens’ group has formed to place an initiative on a future ballot to permanently shut down the plant.

Dewey Lowe, a retired Air Force major general who was appointed general manager in September, quit in July, blasting the elected board of directors for “divisive actions” that devastated employee morale and undermined recovery efforts.

And a special state legislative subcommittee recently began investigating the adequacy of safety plans at Rancho Seco and other California nuclear power plants following the nuclear disaster at Chernobyl in the Soviet Union.

The Nuclear Regulatory Commission has named Rancho Seco as among 10 U.S. “problem plants,” according to documents released earlier this month by a House of Representatives subcommittee. It says the plant has one of the worst efficiency ratings of any in the nation.

Federal investigations have found a history of mismanagement, poor or non-existent maintenance, poor operator training, inattention to detail, failure to learn from past mistakes and manipulation of radioactive measurements to allow discharge of contaminated waste water.

Similar Systems

A NRC report says the December, 1985, overcooling incident “should have been expected” because there have been several failures of similar control systems at other plants built by Babcock & Wilcox Inc. The company also designed the Three Mile Island reactor No. 2 that had the nation’s most serious nuclear accident in March, 1979.

The NRC is conducting an extensive safety review at the eight plants in the United States designed by the firm, but has allowed them to continue operating.

The other seven plants are Arkansas 9 near Russelville, Ark.; Crystal River near Crystal River, Fla.; Davis-Besse near Toledo, Ohio; Oconee 1, 2 and 3 near Greenville, S.C.; and Three Mile Island No. 1, near Harrisburg, Pa.

SMUD officials, while pointing out that the overcooling at Rancho Seco caused no damage to major components, decline to comment on critics’ charges that the NRC and the utility knew the plant was vulnerable to such an accident and failed to take preventive steps. Instead, SMUD officials point out how they are working closely with the federal government to resolve concerns.

Utility officials say the recovery effort involves several improvements in the plant, maintenance on equipment, development of new emergency procedures, and additional employee training, all guided by outside consultants.

Management Changes

“We’re not happy with the capacity factor of the plant and we’re doing everything we can to change that. We’ve made management changes and hired consultants ... We’re very, very hopeful that when it restarts, it will remain on line for some time,” said spokesman Kerry Shearer.

Although Rancho Seco has cost SMUD $1.1 billion since it opened, the electricity it has generated would have cost $1.9 billion if purchased from outside sources, says Shearer. Despite problems, he says, the plant has generated about 70% of Sacramento’s total needs since startup in April, 1975, helping keep rates lower than those of many other utilities.

But because the plant produces more than half of SMUD’s electrical demand, the continuous shutdown has forced the utility to buy considerable amounts of power from outside sources.

Faced with a potential $16-million deficit due to the plant outage, the SMUD board of directors--despite loud protests from customers--approved nearly a 10% rate increase beginning July 1.

The utility posted a $9.2-million 1985 deficit--the first in SMUD’s 39-year history--despite two separate rate hikes of 14% during the year. SMUD officials attributed the loss to poor performance at Rancho Seco, which was shut down five times last year for a total of 248 days.

View of Credit Falls

SMUD’s financial woes worsened when two firms, which rate the credit of institutions that issue bonds to finance their activities, downgraded their confidence in the utility’s credit.

SMUD officials say the drop in the district’s bond rating will drive up the cost of borrowing money for construction projects and probably ultimately force even more rate hikes.

Rancho Seco has proven so troubled in recent months that another utility, sensitive to nuclear power woes, has taken actions branding the plant as unreliable and compounding SMUD’s financial plight.

Pacific Gas & Electric has launched a legal battle to break an agreement that allowed it to use excess power from Rancho Seco. PG&E; is withholding millions of dollars in payments to SMUD, saying it was paying for electricity it had no chance of receiving.

In response, SMUD began withholding millions of dollars in power payments to PG&E;, a private utility that serves the surrounding Northern California area.

PG&E; Lawsuit

PG&E; says in a lawsuit that Rancho Seco outages were “due to SMUD’s mismanagement and neglect, and to . . . failure to exercise due diligence and reasonable care or to follow prudent industry operating practices.”

The plant’s history has been a troubled one.

On dedication day, Oct. 19, 1974, it suffered a valve problem in a steam turbine, which forced a shutdown. A gush of steam left the crowd wondering, but the utility skipped informing the public.

Since the plant became commercially operational in 1975, it has run less than 50% of the time.

Continual shutdowns created more radioactive cooling water--drained from plant systems after the incidents--than Rancho Seco’s storage facilities could hold.

SMUD had to dump more than 13 million gallons into a creek the first nine years of the plant’s operation. NRC investigators found the utility had manipulated radioactive measures to allow discharge of the contaminated waste water.

Area residents have filed a civil lawsuit against SMUD that seeks $1 billion, but the utility and the NRC says the public has not been endangered.

Used Fuel Stored

Rancho Seco also has been forced to store large quantities of low-level waste and highly radioactive used fuel at the site due to a lack of dumps elsewhere.

SMUD says the public is safe, while critics insist the plant now holds enough radioactive material to heavily contaminate Sacramento County many times over.

Some members of the SMUD governing board have acknowledged that plant workers and contractors were not always supervised to assure they were doing their jobs and weren’t always held accountable when they made mistakes.

The directors said they didn’t pay enough attention to the troubled plant, were too trusting of managers, and after realizing there were serious management, staffing, training and maintenance problems, were too slow to demand reform.