May 6, 2003 — The Nuclear Regulatory Commission has begun a Special Inspection into potential leakage in the bottom of the reactor vessel at the South Texas Project nuclear power plant, Unit 1. The facility, which has two operating reactors, is located near Bay City, Texas.
STP Nuclear Operating Company officials notified the NRC on April 13 that they identified potential leak indications at the bottom of Unit 1’s reactor vessel during a visual inspection. Small deposits of boron crystals were identified at two bottom mounted instrumentation penetrations, indicating a possible leak of reactor coolant.
The water that circulates through a pressurized water reactor to cool the nuclear fuel contains a low concentration of boric acid. This borated water can potentially leak through flanges, pump and valve seals, and other parts of the reactor cooling system and cause corrosion. STP Unit 1 has been shut down since March 25 for a refueling outage.
The NRC’s Special Inspection team, comprised of metallurgical and engineering specialists, will monitor the utility’s investigation and evaluation of the potential leaks. The inspection is being conducted to better understand the circumstances surrounding the boron crystal deposits and to evaluate the licensee’s corrective action plans.
Following completion of the inspection, the NRC will hold a meeting in the plant vicinity to discuss the inspection findings. The meeting will be open to public observation.
The inspection report, issued about four weeks after the inspection, will be available on the agency’s web site and through its Electronic Reading Room at http://www.nrc.gov as an Agencywide Document Access and Management System (ADAMS) document. Help in using ADAMS is available through the NRC Public Document Room at 301/415-4737 or 800/397-4209.