June 23, 2011

***FOR THE RECORD***

NRC RESPONDS TO CITIZENLETTER MESSAGES

The Nuclear Regulatory Commission has received thousands of nearly identical 

CitizenLetter© messages voicing concerns about U.S. operating nuclear power plants in light of 

Japan’s tragic earthquake and tsunami on March 11, 2011, and the subsequent events at the 

Fukushima Daiichi Nuclear Power Station. The CitizenLetters mention the Pilgrim, Indian Point, 

Diablo Canyon and San Onofre plants, among others, asking for “immediate inspections” and 

making claims about the plants’ ability to withstand severe natural events.

First off, thank you to everyone who sent a CitizenLetter. The public’s active 

involvement in the NRC’s processes helps us not only fulfill our mission of keeping you safe, 

but it also helps us do our jobs openly and transparently. 

The NRC remains convinced that U.S. nuclear power plants are designed and operated in 

a manner that protects public health and safety. All U.S. nuclear power plants are built to 

withstand external hazards, including earthquakes, flooding, and tsunamis, as appropriate. Even 

those plants that are located in areas with low and moderate seismic activity are designed for 

safety in the event of such a natural disaster. Each plant is designed to withstand the possible

ground movement that is appropriate for its location, given the earthquake sources that may 

affect the site. Ground movement is a function of both the magnitude of the earthquake and the 

distance from the fault to the specific site. The seismic responses of the structures, systems, and 

components associated with these facilities are site-specific, based on either identified faults and 

tectonic capabilities in the area or the region’s seismic zone activity, whichever can generate 

stronger ground motion. The Diablo Canyon and San Onofre plants are located in a region that 

experiences higher levels of seismic activity than most of the United States and are designed 

accordingly. The NRC does not believe the seismic hazards associated with the Diablo Canyon 

and San Onofre plants can be directly compared to the events at Fukushima. 

The events that occurred in Japan are the result of a combination of highly unlikely 

natural disasters. These include the fifth-largest earthquake in recorded history and the resulting 

devastating tsunami. This earthquake occurred on a “subduction zone,” a tectonic plate boundary 

where one tectonic plate is pushed under another plate and creates enough stress in the Earth’s 

crust to produce earthquakes of the largest magnitude. Subduction zone earthquakes are also 

required to produce the kind of massive tsunami seen in Japan. In the continental United States, 

the only subduction zone is the Cascadia region, off the coast of northern California, Oregon and 

UNITED STATES

NUCLEAR REGULATORY COMMISSION

WASHINGTON, D.C. 20555-0001
Washington, and this is the only U.S. location that could generate a continental earthquake and 

tsunami as large as the March 11 event in Japan. The only nuclear plant near the Cascadia 

subduction zone is the Columbia Generating Station in eastern Washington. This plant is located 

approximately 225 miles from the coast and approximately 300 miles from the subduction zone, 

so the ground motions estimated at the plant are far lower than those seen at the Fukushima 

plants. This distance also precludes the possibility of a tsunami affecting the plant. Both the 

Diablo Canyon and San Onofre plants’ tsunami analyses include the possibility of a Cascadiagenerated tsunami. Outside of the Cascadia subduction zone, earthquakes are not expected to 

exceed a magnitude of approximately 8. 

In addition to the NRC’s usual inspection activities, since the events at Fukushima the 

agency has twice inspected all U.S. nuclear power plants specifically for issues related to 

emergency procedures and resources. Both inspections showed U.S. plants are prepared to use 

those emergency measures to keep the public safe. Temporary Instruction 2515/183 provided 

instructions for NRC inspectors to perform independent assessments of “B5b” measures, which 

would help keep the reactors and spent fuel pools safe even after the sudden loss of significant 

areas of the plants. The results of these inspections indicated that although some deficiencies 

were identified and subsequently corrected, the licensee’s plans would still ensure that critical 

cooling functions would be provided. The individual inspection reports are available at the 

NRC’s public website at the following link: 

http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/follow-up-rpts.html.

TI 2515/184 provided instructions for NRC inspectors to examine the plants’ severe 

accident management guidelines (SAMGs), which are meant to reduce the severity of situations 

where a reactor core has been damaged. The inspectors were told to determine: (i) that the severe 

accident management guidelines (SAMGs) are available and how they are being maintained, and 

(ii) the nature and extent of licensee implementation of SAMG training and exercises. The 

results of these inspections also indicated that although some deficiencies were identified they 

have either been corrected or entered into Correction Action Programs and the identified 

deficiencies did not preclude any critical mitigation functions from being performed. Individual 

inspection reports associated with the TI 251/184 inspections are also available on the NRC’s 

public website: http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/SAMGs.html.

In addition, the NRC issued Bulletin 2011-01 requiring all holders of operating licenses 

for nuclear power reactors to provide a comprehensive verification of their compliance with the 

regulatory requirements in 10 CFR 50.54(hh) associated with “B5b” mitigating strategies for 

beyond design basis events. At a Commission briefing on June 15, 2011, Martin Virgilio, Deputy 

Executive Director for Reactor and Preparedness Programs, indicated that the NRC had 

completed reviewing approximately 75% of the 30-day licensee responses to Bulletin 2011-01 

and there were no cases identified where mitigating equipment was not available or the 

mitigation strategies were not workable. 

The NRC established a senior level task force to conduct both short- and long-term 

analysis of the lessons that can be learned from the situation in Japan. The task force is 

examining all the available information from Japan to understand the event’s implications for the 

United States. They are performing a systematic and methodical review to see if there are 
changes that should be made to NRC programs and regulations to ensure protection of public 

health and safety. This will undoubtedly lead to the identification of issues that warrant further 

study in the longer term. The task force is scheduled to provide a report to the Commission in 

July 2011 identifying the results of its review and providing recommendations for short-term 

action, if necessary, and longer-term study. The NRC will assess all the available information 

and evaluate whether enhancements to U.S. nuclear power plants are warranted.

The NRC believes that it is highly unlikely that a similar combination of events such as 

those which occurred in Japan could occur in the United States, including at the Diablo Canyon 

and San Onofre nuclear plants. The NRC remains convinced that U.S. nuclear power plants are 

designed and operated in a manner that protects public health and safety. The implementation of 

the defense-in-depth principles by the NRC and industry, conservative decision making, use of 

risk insights, the results of the recent TI inspections and continuous routine inspections 

performed by the NRC’s Resident Inspectors, industry initiatives and actions coordinated

through the Institute of Nuclear Power Operations, robust corrective programs, and an absence of 

complacency in responding the events at Fukushima provides for further assurance that the U.S. 

nuclear power plants continue to remain safe.