By Jeff Postelwait
Online Editor, POWERGRID International and Electric Light & Power magazines
April 21, 2011 — As I write this feature, more than a month has passed since the March 11 earthquake and tsunami that touched off the planet’s worst nuclear crisis since Chernobyl. Workers and officials in Japan are still struggling to devise a long-term plan on how to deal with the stricken reactors at Fukushima Daiichi nuclear power plant.
International experts have estimated that the clean up process could take years or decades, but the future of the plant, its fuel, the surrounding area, the people living nearby and the nuclear power industry at large is uncertain to say the least. So I arranged a question and answer session with Nathan Ives, Senior Manager at Ernst & Young, in hopes of gaining some insight on what the future will hold for these and other problems raised by the disaster.
Prior to joining Ernst & Young, Ives was senior plant operations evaluator at the Institute of Nuclear Power Operations where he led the nuclear industry’s effort to redefine performance standards in the areas of operational risk management, high-risk decision management, organizational alignment, and plant operations. Ives authored the guidelines and evaluation methods for these areas.
Jeff Postelwait: On April 12, Japan‘s Nuclear and Industrial Safety Agency raised the rating of the Fukushima event to a level 7 event on the International Nuclear and Radiological Event Scale, which puts the disaster in the same category as Chernobyl. Tell me about this change in ranking. How are these rankings determined? What could change it?
Nathan Ives: INES index rankings are based on the significance of event conditions in three general categories: people and environment, radiological barriers and control, and defense-in-depth.
Recent surveys taken around the Fukushima site revealed a higher release of radioactivity; resulting in the ranking change from 5 to 7. Keep in mind that this ranking is provisional. The event is ongoing and the current ranking may be re-assessed — even downgraded — as more data is collected and analyzed.
JP: Do you believe it’s fair to place Fukushima in the same category as Chernobyl? How was Chernobyl different?
NI: Yes, it is fair, because the criteria for assessing both incidents are the same.
1. Fukushima is a low level 7 event. Chernobyl was significantly over the level 7 threshold. There is no level 8 to further differentiate the two events.
2. The Fukushima accident was initiated by an unpredicted and unprecedented act of nature and was responded to by a well-trained, highly professional operations staff. The Chernobyl accident resulted from errors made by the operating staff and test engineers, some of whom were inadequately trained to manage the facility.
3. Fukushima involves damage to several reactors, collectively compounding the event’s impact. Chernobyl involved massive damage to one reactor.
These differences should be considered to “fairly” compare the two accidents.
JP: The plant operator, Tokyo Electric Power Co., has been criticized for not being forthcoming with the public on the radiation dangers and on the evolving situation on the ground in general. According to North American standards and protocols, how would it have been done differently here?
NI: American emergency response regulations necessitate:
1. An off-site emergency response center that is staffed with both technical and communications personnel. Thus, U.S. nuclear utilities have people dedicated to keeping local officials, law enforcement and the public informed of the situation. Persons holding these positions are well trained and execution of the entire process is periodically tested.
2. An evacuation zone of 50 miles versus the Japanese standard of 12 miles. This difference became important when the Japanese began to find radioactive contamination more than 12 miles from the Fukushima plant.
JP: Early reports from Fukushima claimed that radioactive vapors were released by plant operators to relieve building pressure. Is this standard procedure during an emergency?
NI: A “controlled release” during emergency conditions like those experienced by Fukushima Daiichi is performed per procedural guidelines. In this case, some radioactive vapor was released to relieve pressure inside the reactor’s containment building to maintain its structural integrity.
The released vapor is filtered to retain radioactive particulates within the containment building. While there is a risk of some radioactive release into the environment, a controlled release is preferable to the uncontrolled release that would occur should the building rupture. This action by the Japanese operators potentially averted a much larger problem.
JP: How can Japan begin to contain and clean up the radiation? How can a disaster like this be prevented in the future?
NI: It depends on the type of cleanup the Japanese government ultimately requires. They could demand a green-field cleanup, which would return the site to its natural state before the nuclear reactor was built, or the government may ask for the effected plants to be encased in a “sarcophagus” — an action now being pursued at Chernobyl.
Similarly, the off-site level of contamination deemed acceptable by the Japanese government will determine the extent of environmental and structural decontamination to occur.
It is impossible to anticipate and unreasonable to design a plant for all conceivable conditions. However, it is possible to put in place protocols for responding to and mitigating the adverse impacts of unpredictable events. The industry always is learning, growing and improving on both its operating processes and reactor designs.
The new Westinghouse AP 1000 reactor, for instance, is a design recently approved by the Nuclear Regulatory Commission that employs a passive cooling system using gravity, not electric power, to cool the reactor following a catastrophic event. This design feature will mitigate the impact of a Fukushima-like event where emergency reactor cooling systems lose all power.