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T he Nuclear Regulatory Commission (NRC), an agency within the executive branch of the federal government, has almost exclusive responsibility for setting and enforcing safety standards for U.S. nuclear power plants. How well is the agency meeting its responsibility? Some observers point to the fact that no U.S. reactor has experienced a meltdown since Three Mile Island in 1979 as proof the NRC is effective. Others see evidence to the contrary in the growing frequency of near-misses, including the serious problems discovered in 2002 at the Davis-Besse plant in Ohio.

Meltdowns are too high a threshold by which to measure the NRC’s performance; this would be like assessing an individual’s health based on whether he or she had a pulse. And “near-miss” is too subjective a measure (i.e., how near is near?). Better insights come from the occasions when reactors must remain shut down for a year or more to restore safety levels.

Year-plus outages represent prima facie evidence of how far safety levels have been allowed to drop below acceptable levels; an effective regulator should be capable of monitoring these levels and interceding before year-plus outages are required. Chapter 1 explains in more detail why year-plus reactor outages provide meaningful insights into the NRC’s effectiveness.

To be candid, two assumptions the Union of Concerned Scientists (UCS) made when begin- ning the research for this report proved false,

Walking a Nuclear Tightrope

revealing that the situation was actually worse than we expected. First, based on earlier work we had done for our May 2004 report Nuclear Power in the 2๎€Šst Century: The Risk of a Lifetime, we assumed there had been a total of about two dozen year-plus outages in the United States. Second, we assumed that no reactor other than Davis-Besse had experienced more than one such outage. Instead, our research identified a total of 51 outages lasting a year or more and 10 facilities that experienced more than one such outage.

Where the Problems Begin

Chapter 2 summarizes the who, what, where, when, and why for all of these extended outages. In addition, a case study providing more detailed information and extensive citations for each outage is available on the UCS website at www.ucsusa.org/clean_energy/nuclear_safety.

UCS reviewed the 51 year-plus reactor outages to gain insights into past practices that should be continued or expanded to lessen the chances of future extended outages. We also identified things the NRC should begin doing or should do differently with the same goal in mind. These insights are presented in Chapter 3 and provide the foundation for the conclusions and recom- mendations offered in Chapter 6.

The primary lesson to be learned from year-plus outages is that the most common con- tributing factor is inadequate quality assurance,


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