Part 21 Report - 1998-060

LICENSEE: WESTINGHOUSE ELECTRIC COMPANY SITE: WESTINGHOUSE ELECTRIC COMPANY EN NUMBER:33542 DOCKET: EVENT DATE: 01-15-98 RX TYPE: EVENT TIME: 00:00 VENDORS: NOTIFY DATE: 01-15-98 EMERGENCY CLASS: N/A REGION: 1 STATE: PA TIME: 14:07 OPS OFFICER: BOB STRANSKY 10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH 10 CFR PART 21 REPORT REGARDING TESTING OF SOLID STATE PROTECTION SYSTEM LOGIC WESTINGHOUSE WAS RECENTLY NOTIFIED OF SOLID STATE PROTECTION SYSTEM (SSPS) CIRCUITS THAT WERE NOT FULLY TESTED DURING SEMI-AUTOMATIC TESTING OF THE SYSTEM. THE CIRCUITS NOT FULLY TESTED ARE THE FEEDWATER ISOLATION MEMORY CIRCUIT AND THE P-10 SOURCE RANGE BLOCK MEMORY CIRCUIT. THESE CIRCUITS RELY ON PARALLELING EACH INPUT TO PROVIDE AN OUTPUT WITHOUT UTILIZING THE RETENTIVE MEMORY. THE ORIGINAL TESTING ARRANGEMENT DID NOT VERIFY THAT BOTH OF THE PARALLEL INPUTS ARE OPERATIONAL BECAUSE THE SIGNAL (E.G., P-4 FOR FEEDWATER ISOLATION) THAT INITIATES THE RETENTIVE MEMORY WAS PRESENT AT THE LOGIC GATE INPUT DURING TESTING. AN OPEN LOGIC INPUT ISOLATION DIODE MAY PREVENT THE DESIRED OUTPUT FROM THE LOGIC GATE. FOR ALL PLANTS THAT UTILIZE THE SSPS, THIS LOGIC GATE INITIATES FEEDWATER ISOLATION ON A SAFETY INJECTION SIGNAL OR A HI-HI STEAM GENERATOR WATER LEVEL SIGNAL. SAFETY INJECTION INITIATES A REACTOR TRIP AND, FOR MOST PLANTS, THE HI-HI STEAM GENERATOR WATER LEVEL INITIATES A TURBINE TRIP THROUGH SEPARATE LOGIC WHICH LEADS TO A REACTOR TRIP. THESE FUNCTIONS PROVIDE A P-4 (REACTOR TRIP) SIGNAL SO FEEDWATER ISOLATION IS INITIATED WITH ONLY A SLIGHT DELAY (MILLISECONDS). FOR SEQUOYAH UNITS 1 AND 2 AND WATTS BAR THE TURBINE TRIP SIGNAL FROM HI-HI STEAM GENERATOR WATER LEVEL IS NOT INITIATED SEPARATELY AND DEPENDS ON THE PROPER FUNCTIONING OF THE LOGIC GATE WITH PARALLEL INPUTS, AS DOES FEEDWATER ISOLATION. THE LACK OF FEEDWATER ISOLATION COULD LEAD TO WATER CARRYOVER INTO THE STEAM LINES FOR THESE PLANTS. THE SAME TYPE OF CIRCUIT IS USED FOR THE P-10 SOURCE RANGE BLOCK FUNCTION. THIS IS A BACK-UP FUNCTION TO P-6 AND IF BOTH OF THESE MALFUNCTIONED IT WOULD BE DETECTABLE BY OBSERVING THAT THE SOURCE RANGE WAS NOT BLOCKED AS POWER INCREASED. WESTINGHOUSE HAS DETERMINED THAT CIRCUIT MODIFICATIONS ARE NOT REQUIRED TO TEST BOTH PARALLEL INPUTS. BY PRESSING THE RESET SWITCH, THE RETENTIVE MEMORY SIGNAL (E.G., P-4 FOR FEEDWATER ISOLATION) IS DEFEATED AND THE ABILITY TO OBTAIN AN OUTPUT FROM THE LOGIC GATE CONFIRMS THAT BOTH INPUTS ARE FUNCTIONING. WESTINGHOUSE HAS COMMUNICATED THIS INFORMATION TO ALL PLANTS UTILIZING THE SSPS VIA TECHNICAL BULLETIN ESBU-TB-97-09, DATED DECEMBER 17, 1997.

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