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Union of Concerned Scientists

specifically, 36 of the 51 year-plus outages were caused by broad, programmatic breakdowns that forced plant owners to first fix their flawed practices and then undo the damage inflicted on their plants by years of operating with the flawed practices.

The reasons for year-plus reactor outages by decade provide useful insights. For example, Figure 13 shows the early prevalence of year-plus outages related to events that caused extensive damage (such as the March 1975 fire that damaged cables and equipment at Browns Ferry Units 1 and 2 in Alabama and knocked the reactors out of service for more than a year). These damage recovery outages have largely been eliminated. Similarly, year-plus component replacement/ repair outages, which are needed to replace or repair major components that have degraded (such as recirculation pipes at Massachusetts’ Pilgrim facility in 1983 and steam generator tubes at Maine Yankee in 1993) were prevalent

several decades ago and have been largely eliminated. These types of year-plus outages did not disappear by themselves—the NRC applied considerable regulatory attention to such inci- dents and successfully reduced their frequency.

However, year-plus safety restoration outages necessitated by systemic breakdowns (resulting from flawed operating practices and badly eroded safety margins) are another matter. This type of extended outage, which reflects the “patterns of excessive tolerance” that Edwin Triner warned the AEC about in 1974, is booming. As explained in greater detail in Chapter 4, this trend is the result of the NRC not applying effective regulatory attention to systemic breakdowns, thereby allow- ing such incidents to proliferate.

Until the nuclear power industry and the NRC can successfully demonstrate that they have stopped the significant safety margin erosion caused by systemic failures, it would be impru- dent public policy to cause further erosion by

Figure 13. Reasons for Year-plus Reactor Outages (by Decade)

100%

100%

90%

89%

80%

75%

70%

60%

53%

50%

47%

40%

30%

25%

20%

10%

5%

5%

0%

0%

0% 0%

0%

1966–1975

1976–1985

1986–1995

1996–2005

Damage recovery

Component replacement/repair

Safety restoration

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