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Friday, March 18, 2011
Japan a Study in Managing Risks
By John J. Schinkle
Los Lunas resident
Lessons can be learned from disasters experienced by others. From the earthquake and tsunami catastrophe in Japan one lesson is already apparent.
Several of Japan's nuclear power plants experienced loss of coolant following the intentional automatic shutdown of the reactors as the earthquake hit. The reactors each have four redundant cooling pumps powered by redundant electrical generators that protect the reactor fuel elements from overheating as a result of the inherent decay heat produced by fission products following shutdown.
It seems likely that a common mode failure negated the redundancy in the emergency cooling system. Common mode failure is a risk management term that connotes a single failure that nullifies redundant safety features.
During my engineering career I spent a dozen years evaluating designs and analyzing risks for Department of Energy nuclear facilities. I also served an eight-year sentence as safety director in the DOE Albuquerque field office. A source of considerable frustration involved risk management.
The frustration stemmed from a lack of interest in risk management on the part of DOE policymakers. DOE philosophy generally consisted of mimicking the Nuclear Regulatory Commission approach to nuclear safety.
To oversimplify the NRC process, the staff writes tons of regulations, and then inspectors and lawyers argue whether any given plant is in compliance at any given time. Not that the NRC is unaware of common mode failures. For example, in 1991 the Salem Nuclear Generating Station Unit 2 in New Jersey experienced a simultaneous failure of three independent solenoid valves in an overspeed safety system. The safety system failure allowed a massive turbine generator to spin up to an excessive speed until it self-destructed, also destroying the building that housed it.
A former NRC branch chief responsible for nuclear safety standards told me that risk management techniques such as failure mode analysis have no merit. He said that the NRC approach was to wait until an incident occurred and then write a new safety regulation to deal with the incident.
Considering that a semi-infinite number of things can go wrong, this inevitably results in a mountain of regulations combined with a convoluted design. Indeed, an overwhelmingly complex design and operation was an underlying cause of the Three Mile Island nuclear power plant fiasco.
The consequences of the Japan earthquake and tsunami calamity far exceed the risk of exposure to radionuclides. Nonetheless, the reactor difficulties provide an opportunity for safety authorities to learn a valuable lesson regarding the benefits of risk management techniques.
As an aside, there is a touch of irony in the fact that immediately following the earthquake, America provided aid to Japan via the USS Ronald Reagan aircraft carrier.
This huge ship is powered by two nuclear reactors.
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