U. S. NUCLEAR REGULATORY COMMISSION
OFFICE OF PUBLIC AFFAIRS, REGION IV
611 Ryan Plaza Drive, Suite 400, Arlington TX 76011
|CONTACT:||Breck Henderson (817) 860-8128/e-mail: firstname.lastname@example.org|
RIV: 98-34 September 10, 1998
The Nuclear Regulatory Commission staff will hold a predecisional enforcement conference Monday, September 14, with officials of Arizona Public Service, the operator of the three-unit Palo Verde nuclear power plant near Wintersburg, Arizona, to discuss four apparent violations of NRC requirements.
The conference will begin at 9 a.m. at NRC Region IV offices in Arlington, Texas. The meeting will be open to public observation; NRC officials will be available afterward for questions.
The apparent violations were identified during an inspection conducted between May 26 and July 21 of this year. All four involve the high-pressure safety injection system (HPSI), which is designed to provide emergency cooling water to the reactor core during an accident in which normal cooling water flow is lost.
During a refueling outage at Unit 1 in April 1998, Palo Verde operators discovered that a check valve in the HPSI system was malfunctioning during routine testing. Check valves allow water to flow in only one direction, but this valve was leaking excessively from the direction in which it should have blocked flow. A misalignment of the valve disc inside the body of the valve, which had existed for several years, was determined to be the cause of the problem. A similar check valve in Unit 2 was found to have the same problem. Operators further determined that tests on the check valves conducted prior to April 1998 were inadequate to detect the problem. The malfunctioning check valves would have led to reduced flow from the HPSI system to the reactor core under some accident conditions. The misalignment problem has been repaired at both units.
No decision on the apparent violations or any contemplated enforcement action will be made at this conference. Those decisions will be made by senior NRC officials at a later time.