Accident probe finds N-plant gauges faulty

Press, 11 April 1979, Page 8

Accident probe finds N-plant gauges faulty

NZPA Washington The Government’s senior advisory committee on reactor safety has concluded that the accident at the Three Mile Island nuclear station indicates that it would be “very difficult” for the workers at 43 of the nation’s 72 reactors to understand and properly control similar kinds of accidents because it is possible that their pressure gauges are misleading. The far-reaching conclusion of the Advisory Committee on Reactor Safeguards was contained in a letter to Joseph Hendries, chairman of the Nuclear Regulatory Commission, the Federal body that supervises reactor safety. The analysis and recommendations suggest that the advisory committee concluded 'that the accident at the Three Mile Island reactor near Harrisburg, Pennsylvania. raised technical and procedural problems for the 43 pressurised water reactors — more than half of the reactors in the United States — and was not simply a question of human error on the part of the plant’s owners, Metropolitan Edison.

The advisory committee recommended that new kinds of instruments on all pressurised water reactors be swiftly provided to give reactor workers “an unambiguous indication of the level of fluid in the reactor vessel.” This is important because unless the uranium fuel rods are kept cool, they can crack and possibly release radiation. According to commission investigators, a misunderstanding about the amount of cooling water in the Pennsylvania reactor apparently prompted the workers manually to close down the core cooling system, causing parts of the fuel rods to overheat seriously. The advisory group further said that, “early consideration should be given also to provide remotely controlled means for venting high points in the reactor system, as practical.” This recommendation apparently was aimed at providing a means to vent large hydrogen bubbles such as the one that formed, in the Pennsylvania reactor, which could have caused an explosion.