United States Nuclear Regulatory Commission - Protecting People and the Environment

LICENSEE: CONNECTICUT YANKEE ATOMIC POWER CO.
SITE: HADDAM NECK 1                         EN NUMBER:28328
DOCKET: 05000213                         EVENT DATE: 02-02-95
RX TYPE: PWR                             EVENT TIME: 22:15
VENDORS: W-4-LP                         NOTIFY DATE: 02-03-95
EMERGENCY CLASS: N/A  REGION: 1 STATE: CT      TIME: 00:39
OPS OFFICER: JOHN MacKINNON
10 CFR SECTION: ADAS  50.72(b)(2)(i)      DEG/UNANALYZED COND
UNIT  SCRAM   RX   INIT  INITIAL MODE     CURR   CURRENT MODE
      CODE   CRIT  PWR                    PWR
 1    N       N      0   COLD SHUTDOWN      0   COLD SHUTDOWN

DURING FULL FLOW DYNAMIC TESTING TWO REDUNDANT MOTOR OPERATED
SERVICE WATER BYPASS VALVES FAILED TO FULLY OPEN.
SERVICE WATER BYPASS VALVES (SW-MOV-837 "A" & "B") FAILED TO
FULLY OPEN DURING FULL FLOW DYNAMIC TESTING. THESE BYPASS VALVES
WOULD BE USED TO PREVENT CLOGGING AND/OR TO BYPASS A CLOGGED
SERVICE WATER FILTER DURING A POST LOSS OF COOLANT ACCIDENT
(LOCA), AND TO SUPPLY COOLING WATER TO THE CONTAINMENT AIR
RECIRCULATION FAN COOLERS (FOUR FAN COOLERS). IF THE SERVICE
WATER FILTER PLUGGED UP AND IF NEITHER OF THE SERVICE WATER
BYPASS VALVES COULD BE OPENED DURING A POST LOCA EVENT, THEY
WOULD BE OUTSIDE THE THEIR DESIGN BASIS OF THEIR PLANT.
PER GENERIC LETTER 89-10 (MOV TEST PROGRAM), LICENSEE WAS
PERFORMING FOR THE FIRST TIME A FULL FLOW DYNAMIC TEST OF THE
BYPASS VALVES WITH FULL DIFFERENTIAL PRESSURE ACROSS THE VALVE
(80psid).  SERVICE WATER BYPASS VALVE (SW-MOV-837 "A") FAILED TO
FULLY OPEN WHEN TESTED ON THE MORNING OF 02/02/95. AT 2215ET,
SERVICE WATER BYPASS VALVE (SW-MOV-837 "B") FAILED TO FULLY OPEN
WHEN IT WAS TESTED. BOTH VALVES TRAVELLED IN THE OPEN DIRECTION
FOR ABOUT 1.5 SECONDS BEFORE THEY STOPPED OPENING (TAKES 9
SECONDS TO FULLY OPEN THE BYPASS VALVES). IN BOTH CASES THE
BYPASS VALVE FAILED TO OPEN BECAUSE THEIR MOTOR OPERATED VALVE
TORQUE SWITCH TRIPPED. THE SETTING OF THE TORQUE SWITCHES WERE
CHECKED AND WERE FOUND TO BE AT THEIR RECOMMENDED SETTINGS AS
SPECIFIED BY THE MANUFACTURER & SUPPLIER. SINCE THIS WAS THE
FIRST TIME THAT THESE BYPASS VALVES HAD BEEN OPERATED UNDER SUCH
CONDITIONS AND THE BYPASS VALVES FAILED TO FULLY OPEN, THE
LICENSEE RESET THE TORQUE SWITCH TRIP SETPOINT TO A HIGHER TRIP
SETPOINT.  LICENSEE REPERFORMED FULL FLOW TESTING OF THE BYPASS
VALVES AND THEY OPERATED PROPERLY.
                                                                 
RESIDENT INSPECTOR WILL BE INFORMED BY THE LICENSEE.

Page Last Reviewed/Updated Thursday, March 29, 2012