Before continuining on with this post, I wish to express my very honest and sincere hope for the Japanese people who were afflicted from both the March 11 earthquake and tsunami. I pray for all aspects of their welfare, for their families, for their survival, and for their recovery. I desire for them the quickest humanitarian aid, the speediest access to supplies, and as much comfort as is possible.
Having said this, in my study of the disaster, I'm amazed at the monstrous butchering by the press of the Japanese nuclear situation. If I didn't know better, I'd site inside my US-home with a face mask. The diabolical nature of the current situation seems to be escalating, literally, out of control. Such emotionalization and panoramic fear is not only unfounded, it is detrimental to relief and recovery efforts.
This links you to an aritlce written by Dr. Josef Oehmen of MIT, discussing with appropriate technical accuracy the Japanese reactor situation. If you have time, check it out. I started working on a similar composition until I found this. It has my full endorsement. Below is my assessment.
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Amidst the passionate discussions hovering around the recent Japanese nuclear situation, it is difficult to remove the torrid emotional biases associated with nuclear safety from the actual safety performance. How well have the Japanese Fukushima Daiichi and Daini Nuclear Power Stations actually responded, and what does that philosophically mean for the future of nuclear safety regulation?
In the United States, the Department of Energy (DOE) sets a safety standard for each component of a nuclear facility which pertains to safety, called a Performance Category (PC). One example of a safety component integral to nuclear operability would be the coolant pumping system; another could be the pressure vessel containment room. An upper PC limit is specified (by the DOE) for the amount of natural phenomena activity (i.e., seismic, tsunami) a specific component can handle. DOE non-reacting nuclear facilities comparable to the reacting Daiichi and Daini facilities have been built to withstand the worst seismic activity expected in 10,000 years (the “10,000 year event”), and the worst tsunami expected in 100,000 years (the “100,000 year event”) per regulation (DOE-STD-1020-2002). This means all the structures, systems, and components pertinent to maintaining safety in a nuclear facility would withstand and dissipate the affects of the worst possible estimated seismic activity and tsunami.
The estimates of the seismic and tsunami events are generated by considering a variety of factors. Seismic analyses include considerations of ground acceleration or velocity, natural ground and structural frequency movement and amplification, and the inelastic energy absorption capacity of structures (toughness, ductility, and redundancy). Tsunami analyses include factors such as tidal wave height effects, storm surges, and tides (DOE-STD-1023-1995). The Daiichi and Daini Nuclear Power Stations were build and regulated to withstand and mitigate the effects of a magnitude 8.2 earthquake.
Each nuclear facility is built, regulated, reviewed, and re-assessed at least every 10 years to ensure that the facility is capable of handling effects from the 10,000-year and 100,000-year seismic and tsunami events. If it becomes know that the facility standards or performance are not up to par, corrective actions are immediately taken.
Knowing that nuclear facilities are designed and maintained to meet certain performance criteria under the event of an accident, consider a statement given by the Federation of Electric Power Companies of Japan (FEPC) Washington DC Office as of 4:30pm (EST), March 13, 2011,
“Japanese nuclear facilities are built to exacting safety standards. They are designed to withstand powerful seismic events, such as earthquakes. In this earthquake—the strongest recorded over the past 100 years in Japan—the containment structures of Fukushima Daiichi maintained their structural integrity. These facilities were designed to withstand tsunamis within a range of assumed strength. In this event, however, the force of the tsunami exceeded the assumed range and flooded diesel generators at Fukushima Daiichi power station, thus precipitating the loss of power for the reactor cooling systems.”
The Fukushima Daiichi nuclear facilities met their design standards. The above reference also states that the Fukushima Daiichi and Daini Stations “shut down automatically in response to the earthquake.” The power stations were designed to shut down in the event of an earthquake, and indeed, this is what they did. The nuclear facilities were designed to withstand the effects of the 8.2 magnitude design basis earthquake, meaning the mitigation of an 8.9 earthquake was five times greater than performance standards. However, the safety design range was insufficient to mitigate the effects of the tsunami. Had the nuclear facility been designed to safely consider a larger tsunami, it is reasonable to believe one wouldn’t see the presently-emerging ancillary effects (loss of electrical power, interaction of hydrogen and oxygen vapor). Where then, was the safety performance problem?
There was no safety performance problem. The problem lies in the safety performance design range. Again, in the Japanese situation, structures withstood the affects of the 8.9 magnitude earthquake: they performed as intended. This is an actual triumph for the nuclear safety industry: facilities are standing up to the hazards they were designed to withstand.
Can we expect a similar triumph of hazard mitigation in a US DOE facility? Of course. If the accident falls within the basis of safety design, it is legitimate to assume it will be mitigated, exactly as just witnessed at Daiichi. What about the potential of a natural phenomena accident was more hazardous than the facility was designed to withstand (consider how improbable it would be to have the actual occurrence of the worse-case-scenario tsunami predicted in 100,000 years)? Mother Nature will have to tell.
The reason for concern at the Daiichi station was not the safe design of the reactor, but the initial standards on which the design was based. The concern was the safety performance design range. This lends the very legitimate question, how is the safety range determined? It is a compromise negotiated between the perceived or calculated cost, and the commensurate safety risks or benefits. A simple cost-benefit analysis. Theoretically, a nuclear power plant could be built to withstand the worst perceivable earthquake or tsunami in a million years. However, implementing such stringent safety procedures could be financially irrational and even irresponsible. Finally, the question,
Where does one draw the line between the cost of implementing safety, and the benefits of implemented safety?
This is the true question the media and public should be asking. The Fukushima Daiichi and Daini Nuclear Power Stations responded in the ways they were designed to respond. Greater tsunami affects could potentially have been predicted and even compensated for. If sufficient funds and time were spent in designing and implementing safety processes, we wouldn’t be witnessing white plumes of steam ascending from Daiichi Reactors 1 and 3. The current Japanese state of emergency is not an issue of technological adeptness. The state of emergency, and our future nuclear performance, is more about choosing the appropriate safety performance design range. The real future of nuclear energy should target finding the compromise between cost and safety, and then living with the conscience and consequences of that decision.
1 comment:
Good read. Thanks for the research.
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