Walking a Nuclear Tightrope
Chapter 2 The Nature of ear-plus Outages
T he year: 1966. The Sound of Music won the Oscar for Best Picture. The first epi- sode of Star rek was broadcast. The U.S. Supreme Court protected the rights of persons accused of crimes with its ruling in the Miranda v. Arizona case. The Medicare program began. Walt Disney died. And the Enrico Fermi nuclear generating station north of Detroit, MI, shut down after a partial meltdown of its reactor core. The Detroit Edison Company removed the damaged fuel, repaired the reactor, and restarted the plant in 1970. It marked the first time a U.S. nuclear power reactor experienced an outage last- ing longer than one year, but in the ensuing four decades, 40 additional reactors would experience a total of 50 year-plus outages (Table 1, p. 8).
This report considers three categories of year- plus outages:
Damage recovery outages result from a signif- icant event at the reactor (such as an accident) that causes extensive damage and requires the reactor to be shut down for repair for an extended period.
Component replacement/repair outages result from the degradation of a major reactor component, such as an aging steam generator, that must be replaced or repaired before it fails. In this case, the length of the outage is determined by the time required to replace or repair this component.
Safety restoration outages result from cumu- lative, systemic degradation of reactor compo- nents. A year-plus outage of this kind is not needed to fix damage caused by an accident or to replace or repair a major component, but to fix dozens or even hundreds of equipment problems that have accumulated over time. The vast majority—more than 70 percent—
of year-plus shutdowns have been safety restora- tion outages.