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NRC delivers quake lessons
By RUSTY DENNEN
The earthquake and tsunami that devastated Japan’s Fukushima Dai–ichi nuclear power plant in 2011 is still reverberating on this side of the globe.
The Nuclear Regulatory Commission on Friday released staff guidance to the nation’s 104 nuclear power plants—including North Anna Power Station in Mineral—in implementing three Fukushima lessons-learned orders first issued in March.
The orders require a three-pronged approach in preventing a similar disaster: through design and construction improvements; by adding features to prevent radioactive releases; and by beefing up emergency preparation programs, such as sheltering and evacuation.
Forty minutes after the magnitude-9 earthquake, a 45-foot-high wall of water hit the plant on Japan’s northern coast, knocking out power to five of the six reactors. That led to a loss of coolant and explosions at several reactors as hydrogen gas built up inside the containment structures.
The NRC concluded that the sequence of events in Japan is not likely to occur here, but that enhancements to protect against future natural disasters—which the industry calls “beyond design basis” events—should be implemented.
North Anna, located on Lake Anna, is an example of what that means. The plant’s two reactors shut down when a magnitude-5.8 quake struck on Aug. 23, 2011. The ground motion of the quake exceeded the plant’s design limit, marking the first time a U.S. nuclear plant’s reactors were idled due to an earthquake. There was no significant damage.
Virginia’s second-largest earthquake happened five months after the Fukushima disaster, which contaminated some plant workers and the surrounding countryside.
The NRC’s first order requires U.S. plants to better protect portable safety equipment put in place after the 9/11 terrorist attacks, and to have enough equipment on hand to support reactors and spent fuel pools if power is knocked out. Highly radioactive spent fuel is stored near the reactors in pools of water to cool it enough to be stored in steel casks outside.
The second order applies only to U.S. boiling water reactors that have Mark 1 or Mark II containment designs—the type that were compromised at Fukushima. North Anna’s are pressurized water reactors.
The third requires all plants to install enhanced equipment to monitor water levels in spent fuel pools.
During the transition, plants must provide portable, onsite equipment to maintain those functions until they can be done with resources brought from outside. And they must have the ability to sustain them indefinitely in the event of a disaster.
In addition, new reactors under construction and in the pipeline for NRC combined license permits must be modified to incorporate the new safeguards. North Anna’s combined license application for a third unit is pending and is expected to be completed by the NRC in 2015.
Utilities’ plans on how to implement the orders are due to the NRC by Feb. 28, and must be implemented by Dec. 31, 2016.
Rusty Dennen: 540/374-5431
Key post-Fukushima requirements: preventing accidents with design and construction improvements, mitigation features to prevent radioactive releases, and enhanced emergency preparation programs. For more on the NRC response to Fukushima, visit