Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
LICENSEE: AUTOMATIC VALVES CORPORATION
SITE: AUTOMATIC VALVES CORPORATION EN NUMBER:32253
DOCKET: EVENT DATE: 04-25-97
RX TYPE: EVENT TIME: 00:00
VENDORS: NOTIFY DATE: 05-01-97
EMERGENCY CLASS: N/A REGION: 3 STATE: MI TIME: 16:14
OPS OFFICER: JOHN MacKINNON
10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH
PART 21 REPORT REGARDING FAILURE OF SCRAM SOLENOID PILOT VALVES
ISSUED BY
AUTOMATIC VALVES CORPORATION, NOVI, MICHIGAN.
IN SEPTEMBER, 1996, AUTOMATIC VALVES CORPORATION (AVCO) WAS
NOTIFIED BY VERMONT YANKEE THAT A SCRAM SOLENOID PILOT VALVE WAS
MAKING A BUZZING SOUND (RATHER THAN A HUMMING SOUND) WHEN
ENERGIZED. AVCO DISCOUNTED THE REPORT AND TOOK NO ACTION AT THAT
TIME BECAUSE ALL AC SOLENOIDS HUM TO SOME EXTENT AND THEY ASSUMED
THIS NOISE TO BE A NORMAL AC HUM SINCE NO KNOWN PRODUCT OR
CUSTOMER COMPLAINT FAILURE HAD EVER BEEN RECEIVED BY AVCO DUE TO
AC HUM OR BUZZ.
ON 04/24/97, WHILE VERMONT YANKEE WAS PERFORMING SCRAM TIME
TESTING, THE CONTROL ROD ASSOCIATED WITH THE NOISY SCRAM SOLENOID
PILOT VALVE #06-11-118 (WHICH HAD BEEN NOISY FOR THE LAST SIX
MONTHS) HAD A SCRAM TIME THAT WAS SLOWER THAN THE OTHER CONTROL
RODS THAT WERE BEING TESTED, BUT WAS WITHIN THE TECHNICAL
SPECIFICATION TIME LIMITS.
AVCO HAS DETERMINED THAT THE NOISE WAS DUE TO METALLIC VIBRATION
WITHIN THE SCRAM SOLENOID PILOT VALVE WHICH CAUSED THE VALVE
PERFORMANCE TO DEGRADE. DURING PAST ACCEPTANCE TESTS, AVCO DID
NOT USE AUDIBLE NOISE EMANATING FROM THE SCRAM SOLENOID PILOT
VALVES AS AN ACCEPTANCE CRITERION. AVCO HAS CHANGED THEIR
PROCEDURES TO USE THIS CRITERION. AVCO HAS SUPPLIED SCRAM
SOLENOID PILOT VALVES TO 20 - 25 NUCLEAR POWER PLANTS IN THE
UNITED STATES.
*** UPDATE AT 1640 ON 05/02/97 BY AVCO TODD HUTCHINS TAKEN BY
MacKINNON ***
AFTER INTERVIEWS WITH AVCO INSPECTION PERSONNEL, AVCO MANAGEMENT
PERSONNEL DETERMINED THAT VALVES AT AVCO HAD BEEN INSPECTED FOR
"NOISE" BUT THIS HAD BEEN DONE UNOFFICIALLY WITHOUT ANY
CONSISTENT ACCEPTANCE/REJECTION CRITERIA. DIMENSIONAL
DIFFERENCES BETWEEN SOLENOIDS THAT BUZZ AND HUM ARE NOT
DETECTABLE. THIS WAS CONFIRMED WITH TWO AVCO SOLENOID VALVE
COMPETITORS. DEFINITIONS FOR ACCEPTABLE AC HUM AND REJECTABLE
BUZZ FOR AC SOLENOIDS HAVE NOW BEEN ADDED TO IN-PROCESS
INSPECTION POINTS AND FINAL TEST PROCEDURES AT AVCO.
AVCO RECOMMENDATION: EVEN THOUGH THE SOLENOID VALVE FUNCTIONED,
IT WAS SIGNIFICANTLY SLOWER DUE TO THE AMOUNT OF METALLIC
BY-PRODUCT FROM THE BUZZING SOLENOID PLUNGER. REGARDLESS OF THE
MANUFACTURER, SOLENOIDS SHOULD BE CHECKED FOR BUZZING NOISES AS
IT COULD DEGRADE THE PERFORMANCE AND POTENTIALLY THE LIFE OF THE
VALVE. ANY REBUILDING OF ANY SUPPLIER'S SOLENOID VALVES REQUIRES
A 'NOISE" TEST. SINCE 1970, AVCO HAS NOT BEEN ADVISED OF A
SINGLE SAFETY RELATED AVCO PRODUCT FAILURE DUE TO THIS CAUSE.
VERMONT YANKEE CONFIRMED THIS WITH A CHECK OF THE NUCLEAR PLANT
RELIABILITY DATA SYSTEM.
AVCO WILL RETEST, RECERTIFY, AND RESHIP AT NO CHARGE ANY
SUSPECTED PRODUCT. AVCO WILL REPLACE AND RESHIP AT NO CHARGE ANY
COMPONENT FOUND TO BE FIELD DEFECTIVE.
THE OPERATIONS OFFICER NOTIFIED R1DO (MICHAEL MODES), R2DO (CHUCK
CASTO), R3DO (MARK RING), R4DO (JOE TAPIA) & NRR VERN HODGE.
NOTE: SEE EVENT #32263 FOR A RELATED EVENT.
LICENSEE: VERMONT YANKEE NUCLEAR POWER CORP.
SITE: VERMONT YANKEE 1 EN NUMBER:32263
DOCKET: 05000271 EVENT DATE: 05-02-97
RX TYPE: BWR EVENT TIME: 15:15
VENDORS: GE-4 NOTIFY DATE: 05-02-97
EMERGENCY CLASS: N/A REGION: 1 STATE: VT TIME: 16:36
OPS OFFICER: JOHN MacKINNON
10 CFR SECTION: AINA 50.72(b)(2)(iii)(A) POT UNABLE TO SAFE SD
UNIT SCRAM RX INIT INITIAL MODE CURR CURRENT MODE
CODE CRIT PWR PWR
1 N N 0 COLD SHUTDOWN 0 COLD SHUTDOWN
AUTOMATIC VALVE CORPORATION SCRAM SOLENOID PILOT VALVES FAILED A
SCRAM TIME TEST.
ON 04/24/97, SCRAM SOLENOID PILOT VALVE (SSPV) #06-11-118 FAILED
A SCRAM TIME TEST. PRIOR TO THE SSPV FAILING THE TEST, IT
EXHIBITED A BUZZING SOUND. THE LICENSEE REPLACED THE FAILED SSPV
AND NINE OTHER SSPVs EXHIBITING NOISE. THE PLANT HAS 93 SSPVs
INSTALLED IN THE SCRAM SYSTEM AND 8 SSPVs INSTALLED ON THE MAIN
STEAM ISOLATION VALVES (MSIV).
THE LICENSEE SHIPPED THE FAILED VALVE TO THE SUPPLIER, AUTOMATIC
VALVE CORPORATION, FOR VISUAL INSPECTION, FAILURE ANALYSIS, AND
ROOT CAUSE DETERMINATION.
THE LICENSEE HAS SUBMITTED A BASIS FOR MAINTAINING OPERATION
WHICH INCLUDES ADDITIONAL MONITORING OF SSPVs BY PLANT OPERATORS
TO THE NRC RESIDENT INSPECTOR AND NRC REGION 1.
THE LICENSEE PLANS TO INSPECT THE MSIV SCRAM SOLENOID PILOT
VALVES PRIOR TO PLANT RESTART.
THE LICENSEE INFORMED THE NRC RESIDENT INSPECTOR.
NOTE: SEE EVENT REPORT #32253 FOR BACKGROUND INFORMATION.
