Susquehanna Spent Fuel Pool Concerns, and How I Ended Up at UCS

April 21, 2011 | 4:41 pm
Dave Lochbaum
Former Contributor

In November 1992, Don Prevatte and I submitted a report to the NRC regarding our concerns with spent fuel pools at boiling water reactors (BWRs), of which 35 are operating in the US. We had been consultants working on a team to evaluate the proposed increase in the maximum power level of the two BWRs at the Susquehanna nuclear plant in Pennsylvania. My assignments included the spent fuel pool cooling and cleanup system while Don’s assignments included the reactor building ventilation system. While reviewing each other’s work, we uncovered a problem.

The spent fuel pool for nearly all US BWRs is located inside the reactor building, which also fully encloses the reactor containment building. The reactor building ventilation system was designed to cool rooms and areas in event of an accident to protect emergency equipment from damage caused by high air temperatures.

The design calculation for the reactor building ventilation system considered heat emitted by operating motors, heat emanating from piping filled with hot water, and heat given off by incandescent light bulbs. Collectively, these heat sources amounted to 5.2 million BTUs per hour (a British Thermal Unit, or BTU, is defined as the amount of heat needed to increase the temperature of one pound of water by one degree Fahrenheit).

The cooling system for the reactor building ventilation system was sized to accommodate this amount of heat removal, thus ensuring that emergency equipment would not overheat and fail.

But the design heat load from irradiated fuel stored in the spent fuel pool was 12.6 million BTUs per hour, meaning the spent fuel could emit up to that much heat. Under normal operation, that heat would be carried out of the building by the cooling system. However, safety analyses assume the spent fuel pool cooling system will not be operating during a reactor accident. In that case there would be no heat added to the reactor building from the spent fuel pool pump motors and piping, but without cooling the spent fuel pool water would heat up, boil, and release heat into the reactor building air. A lot of heat—considerably more heat than that present in the reactor building from all other sources, and far more than the cooling system could handle.

The water boiling off the spent fuel pool would condense and drain down into the basement of the building where it would submerge and disable emergency equipment—at least the emergency equipment that had not already been disabled by excessive temperatures in the building. In addition, as water boiled out of the pool and exposed the fuel, the radiation levels inside the reactor building during an accident would prevent workers from entering to open the manual valves that supply makeup water to the spent fuel pool.

Hence, a reactor accident would lead to a spent fuel pool accident. And the boiling spent fuel pool would create conditions inside the reactor building that would disable the emergency equipment needed to cool the reactor core.

As Don and I investigated further, more problems surfaced. Susquehanna’s owner initially justified the situation by saying that the non-safety-related spent fuel pool cooling system would remove the heat, even though it was not credited as doing so in the safety studies. Indeed, we found that emergency procedures directed the operators to open two electrical breakers within an hour of an accident to shut down all non-emergency systems inside the reactor building.

We also found that the standby gas-treatment system—a ventilation system located inside the reactor building that processes air discharged to the atmosphere to reduce its radiation levels by a factor of 100—would shut down if the spent fuel pool water approached boiling because the warm vapor evaporating from the pool would trick sensors into thinking there was a fire, causing inlet dampers to close. And we found that if the spent fuel pool cooling system was not operating, the operators would have no indications of the level or temperature of the water in the spent fuel pool.

The NRC failed to take our report seriously. They didn’t even read it. We had attached all the relevant correspondence between us and the plant’s owner to the report. I made two-sided copies of many of the 35 attachments to save postage costs. But when I took the original report to a copy shop, they mistakenly made single-sided copies and left out every other page. The NRC dismissed our concerns at Susquehanna and every other similarly designed nuclear plant without even noticing that roughly half of the report was missing.

Don and I wrote letters summarizing the spent fuel pool problems to the governors and US senators in the states with BWRs like Susquehanna. We also sent letters to the three congressional committees that oversee the NRC. Congressmen Phil Sharp wrote several letters to the NRC about our concerns, as did several governors and US senators. The NRC granted our request for a public meeting for us to communicate our concerns to the agency. About 15 minutes into that meeting on October 1, 1993, the NRC project manager for Susquehanna was sound asleep and snoring in the first row.

The issues were resolved at Susquehanna by the owners’ commitment to always operate with the spent fuel pools connected to each other. In case of an accident involving the Unit 1 reactor core, the systems on Unit 2 could be used to cool both spent fuel pools without adversely affecting conditions inside the Unit 1 reactor building, and vice-versa. The owner also took steps to install additional instrumentation to enable operators to monitor spent fuel pool water levels and temperatures and resolve the standby gas treatment system design issues.

However, little to nothing has been done to address the spent fuel pool vulnerabilities at other BWRs in this country.

Following this incident, I authored Nuclear Waste Disposal Crisis, a book about spent fuel storage issues. It was released by PennWell Publishing in January 1996. Chapter 8 outlined spent fuel pool safety issues. Chapter 9 detailed our spent fuel pool concerns at Susquehanna. And Appendix A summarized actual spent fuel pool problems that occurred at U.S. nuclear power reactors.

The tragedy at Fukushima Dai-Ichi involved many of the same concerns Don and I raised at Susquehanna. It appears that irradiated fuel in at least two of the site’s seven spent fuel pools has been damaged due to overheating.

The media attention to our efforts to get the NRC to resolve the spent fuel safety issue made nuclear workers across the country aware of our concerns. I started getting calls from both colleagues and strangers asking if I’d champion their safety concerns. I distinctly recall one man telling me, “I don’t want to raise this safety concern and put my job on the line, but since your career is already toast, I thought you’d raise it for me.” I still had a job in the industry at the time, but I appreciated his point. Raising safety concerns in the nuclear industry invokes the gangplank more often than it involves the corporate ladder.

Fortunately for me, Bob Pollard retired from the Union of Concerned Scientists in January 1996. Jim Riccio and Paul Gunter, who I’d met in 1994 during the campaign to call attention to the spent fuel pool problems, suggested I apply for the job. I did, and was hired by UCS. I’ve been working to get the NRC to resolve specific safety issues since then.