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NEI Shares Lessons Learned From CNOs’ Japan Visit

Oct. 31, 2013—One of the major lessons learned from a historic visit to Japan by U.S. chief nuclear officers last month is from Tokyo Electric Power Co.’s response to the tsunami at Fukushima Daini, which survived intact: Leadership is paramount during an extreme event, together with the training and skills of the staff needed to mitigate the event.

Two other critical insights the CNOs came away with, as outlined in an Oct. 30 letter from NEI Senior Vice President and Chief Nuclear Officer Tony Pietrangelo to the Nuclear Regulatory Commission, are:

  • TEPCO’s response to the tsunami at Fukushima Daini demonstrates that the diverse and flexible coping strategy (FLEX) concept is effective. The Daini facility is about 7.5 miles from Daiichi, the site of the 2011 accident.
  • The spent fuel storage pools at Fukushima Daiichi survived the earthquake, tsunami and hydrogen explosions without significant damage to the fuel or significant radiological release.


In September, CNOs representing companies that operate U.S. commercial nuclear energy facilities spent a week in Japan, where they engaged in dialogue with their Japanese colleagues and toured Tokyo Electric Power Co.’s Fukushima Daiichi and Daini sites. Twenty-three CNOs toured the facilities, met with the Japan Nuclear Safety Institute and held a day-long exchange with CNOs representing all the nuclear electric utilities in Japan.

Fukushima Daini experienced the same earthquake and tsunami as Daiichi and also lost power and its emergency diesel generators, but operators there were able to retain or restore core cooling capability and bring all four reactors to cold shutdown within three days of the event.

“Key factors in the stabilization of the Daini reactors were the strong and active leadership during the crisis, in-depth knowledge of the station that was applied to the situation, and motivated personnel who took extraordinary actions to maintain safety at the plant,” Pietrangelo’s letter said.

The letter describes the efforts of Fukushima Daini’s staff, under the leadership of site superintendent Naohiro Masuda, to shut down the reactors.

“Masuda assessed the situation and articulated a clear and compelling vision to plant personnel to return the plant to a safe condition,” the letter said. “In a period of 30 hours, plant staff replaced residual heat removal pump motors and laid and energized 5.5 miles of heavy-duty electric cables.”

This demonstrated to the U.S. CNOs the importance of training and leadership in responding to extreme events.

“The primary lesson learned is that leadership and training matter just as much as having the right equipment,” the NEI letter said. “Our industry’s CNOs believe that our plant leaders and staff are rigorously trained and qualified, exhibit the necessary attributes to succeed in such events, and they will work closely with NEI and the Institute of Nuclear Power Operations to ensure this capability remains in place.”

The response at Fukushima Daini also underlined the importance of the industry’s FLEX strategy in responding to extreme events. While the staff at Daini had no pre-planned procedures, training or portable staged equipment at the site as called for under FLEX, elements of their response mirrored the FLEX procedures and objectives.

“There are several elements of TEPCO’s response at Fukushima Daini that match the U.S. FLEX approach … including steps taken by control room operators, use of equipment from other nearby sites or suppliers, and the use of government assets to assist with transportation or other logistics,” Pietrangelo said.  

“If the personnel at Fukushima Daini were successful in preventing core damage in the units lacking AC power without pre-planning, pre-staging, off-site support and training—all facets included in the FLEX strategy—then the U.S. industry has great confidence we will be able to respond successfully to similar extreme natural events,” the NEI letter said.

The third lesson learned by the CNOs was confirmation that spent fuel pools are robust structures that can withstand extreme events.

“Even after the force of the earthquake and explosion rocked the Daiichi facility, the fuel racks and fuel assemblies were intact and did not pose a threat to public safety,” the letter said.

This corroborates recent NRC findings on the robustness of fuel pools and against the need for the expedited removal of fuel from the pools (see Nuclear Energy Overview, Oct. 10).

“Evidence gained from water sampling and videos of the Fukushima Daiichi spent fuel pools bolsters recent NRC staff comprehensive evaluations that conclude there is no need for additional regulatory action to require the expedited removal of spent fuel from the storage pools,” the letter said.

For more coverage on the CNOs visit to Japan, see the NEI Nuclear Notes blog.