The inspectors identified that the licensees monthly surveillance test procedure for demonstrating operability of the
SGT system may not include appropriate quantitative or qualitative acceptance criteria for determining that the system was capable of performing its specified safety function. This issue is considered to be an Unresolved Item pending additional review by the inspectors to determine whether the surveillance test procedure was adequate to satisfy the surveillance testing requirement. The inspectors reviewed the licensees performance of surveillance testing that was accomplished in accordance with procedure
CPS 9067.01,
Standby Gas Treatment System Flow/Heater Operability, Revision 31a. This surveillance test procedure was performed to satisfy TS
Surveillance Requirement (SR) 3.6.4.3.1, which required that each
SGT subsystem (or train) be operated for Y 10 continuous hours with the heaters operating once every 31 days. As described in the
UFSAR, the safety function of the
SGT system is to minimize the offsite release of radioactive materials that leak from the
primary containment into the
secondary containment following a design basis accident to limit the offsite and control room dose to the guidelines of
10 CFR 50.67. According to the Bases for TS
SR 3.6.4.3.1: Operating each
SGT subsystem from the main control room for Y
10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> ensures that both subsystems are
operable and that all associated controls are functioning properly. It also ensures that blockage, fan or motor failure, or excessive vibration can be detected for corrective action. Operation with the heaters on (automatic heater cycling to maintain temperature) for Y 10 continuous hours every 31 days eliminates moisture on the adsorbers and
HEPA [high efficiency particulate air] filters. During review of
CPS 9067.01, the inspectors noted that the procedure did not have specific steps to ensure that flow blockage did not exist by verifying that each
SGT subsystem provided sufficient air flow. The acceptance criteria specified in Step 9.1.1 of the procedure required only that the
SGT train operates for Y
10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with flow through the train and the heater is
operable. Although
SGT subsystem inlet flow was recorded, there were no acceptance criteria in the procedure to evaluate whether each subsystem was capable of providing the minimum required air flow to meet its safety function. According to the
UFSAR, the
SGT system was designed with a flow control valve that maintains flow at 4000 cubic feet per minute (A 10%); however, there was no comparison of the recorded flow rates with the design flow rate to ensure that the fan and/or the flow control valve were operating properly or that there was no flow blockage. Although pre-filter and
HEPA filter differential pressures were recorded, the acceptance criteria provided in Step 9.2.1 of
CPS 9067.01 only established criteria for dirty filter replacements. The criteria were not used to evaluate whether each subsystem was capable of providing the minimum required air flow to meet its safety function. Although
SGT subsystem inlet and outlet temperatures were recorded three times during the 10-hour run, there were no acceptance criteria in the procedure to evaluate whether the heater was capable of providing sufficient heat to eliminate moisture on the adsorbers and
HEPA filters. There were also no specific steps in
CPS 9067.01 to measure and evaluate fan and motor vibration levels or to locally assess the running subsystem for abnormalities. Local inspection of the subsystem during operation (e.g., checking rotating equipment for abnormal temperatures, odors, noise and/or vibration) would ensure that blockage, fan or motor failure, or excessive vibration could be detected for corrective action. The inspectors discussed these observations with the licensee and questioned whether simply verifying that the subsystem operates for Y
10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> with the heater energized provided an adequate demonstration that each
SGT subsystem was capable of performing its specified safety function to satisfy TS
SR 3.6.4.3.1. This issue is considered to be an Unresolved Item (
URI 05000461/2009005-02) pending additional review and resolution of open questions to determine whether the surveillanc
