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I-97-24 March 11, 1997
The Nuclear Regulatory Commission has proposed a $160,000 civil penalty against Duquesne Light Company for alleged violations of NRC requirements at its Beaver Valley nuclear power plant, in Shippingport, Pa.
Four of the alleged violations stem from inadequate control over repairs to the Unit 2 reactor head vent system last December. The fifth pertains to a failure to identify and correct -- for roughly 13 years -- the improper positioning of two isolation valves for power operated relief valves on Unit 1.
In the case of the head vent system repair violations, the violations were found after the NRC staff asked questions about system leak testing adequacy in December. While trying to halt a small leak from a blind flange, or piping collar, downstream of a normally shut 1-inch isolation valve, a vendor hired by the company had injected sealant into the Unit 2 head vent system. The head vent system is located at the top of the reactor vessel and is used to vent gases and relieve pressure, when needed. However, in preparing for the injection, plant engineering staff erred in specifying the temperature constraints for the sealant's application.
Consequently, the sealant failed to harden properly, migrated to unintended portions of the head vent system and degraded the proper operation of the system's flow control valves, due to sealant accumulating on valve seats. In addition, the procedural controls used during the work were not commensurate with its safety importance, and the vendor procedures used to perform the repairs had not been properly reviewed and approved.
Although the head vent system relief flow paths were not completely blocked at the time of the plant staff's investigation of the problem, the sealant would have hardened over a long period of time and may have caused the flow control valves to remain stuck in the closed position, thereby blocking the flow paths and rendering the system inoperable.
The proposed fine for these violations is $110,000.
The fifth alleged violation, dealing with the positioning of Unit 1 relief valves, was discovered during an NRC inspection conducted at the plant from September 29 to November 16, 1996. It was determined that two of three pressurizer power-operated relief valve block valves had been left in the shut position, a situation contrary to plant design and a change performed without a required safety evaluation. Further, plant employees missed several chances between 1981 and 1996 to identify the problem, assess the associated risk significance and correct the situation.
Plant officials said the valves were originally closed as a temporary measure to address leakage and seismic concerns. But piping modifications were completed in 1981 to alleviate the seismic concerns and the leakage was resolved in 1982-83. NRC thus considers it a significant condition adverse to safe operation for these valves to be left closed. This finding takes on additional regulatory significance in light of the recent discovery of other incorrectly positioned equipment.
The proposed fine for that alleged violation is $50,000.
Duquense Light Company has 30 days either to pay the proposed fine or to request in writing that part or all of it be withdrawn.
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