Northeast Utilities' (NU) Haddam Neck reactor, also known as Connecticut Yankee, may be on the verge of a permanent shutdown following a series of mechanical problems, new discoveries of inadequate construction, and safety lapses compounded by a bleak economic outlook.
The utility is now conducting an internal review of the economics of the reactor, as a prelude to making a decision about its future. Its report is due to be completed by the end of October.
The rumor among plant workers is that the economic review will conclude that Haddam Neck should remain open, because Northeast would be too embarrassed to close its only Connecticut reactor not currently on the NRC's problem plants list (all three of NU's Millstone reactors are on the list).
But recent revelations about deficiencies at Haddam Neck, as well as a serious safety incident on September 1, 1996, raise serious doubts about the reactor's continued viability.
A September 12, 1996 NRC inspection report, for example, found that some of the plant's emergency core cooling system piping is too small to provide enough water to prevent a meltdown under worst-case scenarios. The NRC said this "significantly compromised plant safety."
Moreover, the piping is original to the plant, meaning this condition has existed for the past 28 years. Northeast did not report the condition to the NRC until July of this year.
The importance of this was underscored by the September 1 incident, which the NRC has described as a "significant precursor event." In fact, according to the NRC, the Haddam Neck came within 52 minutes of boiling off the water covering the reactor vessel.
The incident began on August 28, when through operator error a nitrogen bubble began to form in the reactor vessel, displacing the water. According to an NRC account of the incident, "Operators were unaware of actual reactor vessel level during this event," and "Reactor vessel level decreased to approximately 2 1/2 feet about the point of RHR [residual heat removal] pump cavitation."
To make matters worse, the "A" residual heat removal heat exchanger was removed from service on August 31 due to a leak, and the "B" RHR pump was found to be inoperable.
Said the NRC, "The loss of RHR procedure requires the charging pumps be operable to refill the RCS (reactor coolant system). These pumps were not available during this event...If the RHR system was lost, timely restoration of forced circulation using a reactor coolant pump would have been difficult...Nitrogen gas could have adversely impacted the ability of the steam generators to remove decay heat by natural circulation." A low pressure injection system would have been the only system available to attempt to cool the reactor.
However, the nitrogen gas bubble stabilized on its own, and the emergency systems were not needed.
The NRC harshly criticized NU for the event, citing numerous instances of poor procedure quality, failure to implement procedures, "lack of a questioning attitude," inappropriate decision-making, lack of instrumentation, inadequate training, poor equipment condition, and untimely technical response, among other citations. A sizable fine and numerous violations are likely.
Other problems at Haddam Neck include a number of errors in the plant's Updated Final Safety Analysis Report. These are critical, since emergency procedures are based on this report--errors can mean adoption of unsound procedures to follow in an emergency. It seems likely that the NRC would require NU to examine and correct the document before restart--a labor-intensive and lengthy process.
In addition, an August 1, 1996 NRC inspection report found that "engineering calculations and analyses relied on to assure the adequacy of the design of key safety systems, such as station batteries, emergency diesel generators, containment air recirculation system and service waster system, were incomplete or incorrect."
Replacing the emergency core cooling piping would be another expensive proposition--the ten-inch piping throughout the plant would have be replaced with twelve-inch pipes.
The reactor's steam generators are in poor shape, and as far back as 1993 NU (and the NRC as well) concluded that it would not be economical to replace them.
There are also cracks in the containment, and as reported in the July 1996 Nuclear Monitor, numerous or inadequate bolts and welds in the structure supporting the main feedwater piping.
Further, among at least six criteria the NRC has listed for restart, one involves NU obtaining a license amendment--which may give activists an opportunity to raise issues before an Atomic Safety and Licensing Board. Already, activists are gearing up to challenge NU on a wide variety of safety issues.
It seems apparent that NU cannot successfully operate five nuclear reactors (Haddam Neck, Millstone & Seabrook). At this point, despite the rumors, it appears Haddam Neck will be the first to go. The bigger question is whether NU can successfully operate any reactors.