Part 21 Report - 1998-540
LICENSEE: ILLINOIS POWER CO.
SITE: CLINTON 1 EN NUMBER:34548
DOCKET: 05000461 EVENT DATE: 07-20-98
RX TYPE: BWR EVENT TIME: 00:00
VENDORS: GE-6 NOTIFY DATE: 07-21-98
EMERGENCY CLASS: N/A REGION: 3 STATE: IL TIME: 09:19
OPS OFFICER: DICK JOLLIFFE
10 CFR SECTION: CCCC 21.21 UNSPECIFIED PARAGRAPH
UNIT SCRAM RX INIT INITIAL MODE CURR CURRENT MODE
CODE CRIT PWR PWR
1 N N 0 COLD SHUTDOWN 0 COLD SHUTDOWN
10-CFR-PART-21 REPORT - SHRINKAGE AND CRACKING OF MEDIUM AND HIGH
DENSITY SILICONE PENETRATION SEALS DUE TO COEFFICIENT OF THERMAL
EXPANSION
ON 02/20/98, WHILE PERFORMING A WALKDOWN TO QUALIFY PENETRATION
SEALS IN ACCORDANCE WITH NUREG 1552, "FIRE PENETRATION SEALS IN
NUCLEAR POWER PLANTS," ILLINOIS POWER (IP) IDENTIFIED CRACKS IN
PENETRATION SEAL DG-762-01-5003. THE CRACKS EXTENDED COMPLETELY
THROUGH THE SEAL IN THE M-BOARD SEPARATOR MATERIAL AT THE
INTERFACE BETWEEN THE M-BOARD AND THE SF-60 SEALANT AND BETWEEN
THE SF-60 SEALANT AND A PIPE PASSING THROUGH THE SEAL. THE
M-BOARD IS A REFRACTORY FIBER BOARD MADE PREDOMINANTLY OF ALUMINA
SILICA USED WITHIN THE PENETRATION SEAL TO DIVIDE A PENETRATION
INTO SECTIONS FOR WHICH A TESTED DESIGN CONFIGURATION CAN BE
APPLIED. THE SEAL WAS DESIGNED AND INSTALLED BY BISCO, A
SUBSIDIARY OF THE BRAND COMPANIES, IN PARK RIDGE, ILLINOIS. (THE
BISCO ORGANIZATION NO LONGER EXISTS.) THE BISCO SF-60 SEALANT
MATERIAL WAS MANUFACTURED BY DOW CORNING AS SYLGARD 170 (BISCO
SF-60 AND BISCO SF-150NH) MATERIAL.
INSPECTIONS OF OTHER SIMILAR PENETRATION SEAL CONFIGURATIONS
REVEALED THAT THE SHRINKAGE ISSUE IS A GENERIC CONCERN FOR MEDIUM
AND HIGH DENSITY PENETRATION SEALS THAT HAVE CONFIGURATIONS WITH
DIMENSIONS GREATER THAN 12 INCHES. THE CRACKS ARE ATTRIBUTED TO
SHRINKAGE DUE TO THE VOLUME COEFFICIENT OF THERMAL EXPANSION OF
THE CURED MATERIAL (APPROXIMATELY 8% FOR EACH 100�C OF
TEMPERATURE DIFFERENTIAL). CLINTON POWER STATION HAS
APPROXIMATELY 800 SEALS THAT MAY BE SUSCEPTIBLE TO THIS
SHRINKAGE. AS OF 07/10/98, IP HAD INSPECTED 157 OF THE SUSPECTED
PENETRATION SEALS AND FOUND UNACCEPTABLE CRACKS/GAPS IN 32
PENETRATIONS.
IP PLANS TO INSPECT AND REWORK/REPAIR THE SUSPECTED PENETRATION
SEALS AS NECESSARY. RESOLUTION OF THIS ISSUE IS CURRENTLY
SCHEDULED TO BE COMPLETED BY MAY 1999.
THE LICENSEE HAS NOTIFIED THE NRC RESIDENT INSPECTOR.
Page Last Reviewed/Updated Wednesday, March 24, 2021