Lessons-Learned From the Indian Point Unit 2 Steam Generator Tube Failure: ARegulatory Perspective on Technical Issues

摘要

Workers at Indian Point Nuclear Power Plant, Unit 2 (IP2), manually shut down the reactor in Buchanan, N.Y., at 7:29p.m. on Tuesday, February 15, 2000 following indications of a steam generator tube failure in one of the plant's four steamgenerators. The operators received a nitrogen-16 alarm in the 4-loop, Westinghouse, pressurized-water reactor which isindicative of a steam generator tube failure while the unit was at 99% power. The unit has four Westinghouse Model 44 SGswith mill annealed alloy 600 tubing, carbon steel drilled hole tube support plates (TSPs), and partial depth rolled joints in thetubesheet. Subsequent inspections revealed that the source of the leakage was Primary Water Stress Corrosion Cracking(PWSCC) at the apex of a row 2 U-bend tube in steam generator 24.An IP2 steam generator tube failure lessons-learned task group was formed to conduct an evaluation of the staff'stechnical and regulatory processes related to assuring steam generator tube integrity in order to identify and recommend areasfor improvements applicable to the US Nuclear Regulatory Commission and/or the industry. The findings of the lessonslearnedtask group based on the February 15 tube failure will be presented in this paper.