05000325/LER-1995-001, :on 950106,two Inoperable CR Accumulators Resulted in Entry Into Ts.Replaced C11-111 Valves for Two HCUs
| ML20086A133 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 06/23/1995 |
| From: | Mcgowan J CAROLINA POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML20086A131 | List: |
| References | |
| LER-95-001, LER-95-1, NUDOCS 9507030072 | |
| Download: ML20086A133 (3) | |
| Event date: | |
|---|---|
| Report date: | |
| 3251995001R00 - NRC Website | |
text
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NRC FORM 366 U.S. NUCLEAR RESULATORY COMMISSION APPROVED OMB NO. 31504104 i
(5/92)
EXPIRES: 5/31/95 e
ESTIMATED BURDEN PER RESPCNSE TO COMPLY WITH THib INv 0RM ATION COLLECTION REQUEST: 50.0 HRS.
FORWARO LICENSEE EVENT REPORT (LER)
COMMEuTS REGARD,No.URDEN ESTIMATE TO THE INgDRuATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMIS$10N. WASHINGTON, DC 2C555-0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20603.
FACILITY NAME (1)
DOCKET NUMBER (2)
PAGE (3)
Brunswick Steam Electric Plant, Unit 1 05000325 1 of 3 TITLE (4)
TWO INOPERABLE CONTROL ROD ACCUMULATORS RESULT IN ENTRY INTO TECHNICAL SPECIFICATION 3.0.3.
EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (B)
MONTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NUMBER 05000 01 06 95 95 01 06 23 95 FACitrTY NAME DOCKE1 NUMBER 05000 THIS REPORT IS SUBMITTED PURSUANT TO THE REQ'JIREMENTS OF 10 CFR 1:(Check one or more of the followingM11)
OPERATING MODE (9) 20.402(b) 20.405(c) 50.73(aH2Hiv) 73.71(b) a c
(aH Hv) c)
POWER 100 LEVEL (10) 20maH1 Hii) f13 etch 2) 50.73(aH2Hvii)
OTHER 20.405(aH1Hiii)
X 50.73(aH2Hi) 50.73(aH2HviiiHA)
(Specify in Abstract 20.405(aH1)(iv) 50.73(aH2Hii) 50.73(aH2HvisiHB) 20.405(aHIHv) 5033(aH2'{iii) 60.73(aH2Hx)
LICENSEE CONTACT FOR THIS LER (12)
NAME TELEPHONE NUMBER Jeanne F. McGowan, Regulatory Affairs Specialist (910) 457-2136 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
^'
CAUSE
SYSTEM COMPONENT MANUFACTURER
CAUSE
SYSTEM COMPONENT MANUFACTURER PRDS p
MONN DAY YEAR SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED SUBMISSION g,
gg DATE (15)
(if yes, complete EXPECTED SUBMISSION 0ATEI ABSTRACT (Umit to 1400 spaces, i.e. approximately fifteen single space typewntten lines) (16)
On January 6, 1995, Unit I was operating at 100% power. At 0126 hours0.00146 days <br />0.035 hours <br />2.083333e-4 weeks <br />4.7943e-5 months <br />, a Control Rod Drive Hydraulic Control Unit (HCU) accumulator alarm was received on HCU 06-39 due to low nitrogen pressure.
A previous alarm had been received on HCU 18-23 due to low nitrogen pressure.
Both accumulators had previously been recharged and Work Requests / Job Orders were initiated to replace the C12-111, HCU Accumulator Gas Side Isolation Valves.
Technical Specification 3.0.3 was entered due to two HCU accumulators being out of service simultaneously.
The C11-111 valves were replaced on both HCUs and at 0352 hours0.00407 days <br />0.0978 hours <br />5.820106e-4 weeks <br />1.33936e-4 months <br /> the HCUs were declared operable and Technical Specification 3.0.3 was exited. The cause of the event is under investigation.
Preliminary results indicate a potential problem with the valve body 0-rings.
Corrective actions included replacing the C11-111 valves on the affected HCUs.
The safety significance is minimal. With the reactor at rated pressure, the scram i
requirements are met without assistance from the HCUs.
l The cause classification for this event per the criteria of NUREG-1022 is Design, Manufacturing, Construction / Installation.
9507030072 950622 DR ADOCK 05000325 PDR
NRC FdRM 386A
. U. S. NUCLEAR REIULATORY COMMISSION APPROVED OMB NO. 3160-0104 (6/92)
EXPIRES: 5/31/96 i
j ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THl$
INFORMATION COLLECTON REQUEST: 50.0 HRS.
FORWARD LICENSEE EVENT REPORT (LER)
COuuENTS REGARDiNG ouRDeN ESTuATE TO THe :NFORuATiON AND TEXT CONTINUATION RECORDS MANAGEMENT BRANCH (MN88 7714L U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON. DC 20555-0001. AND TO j
THE PAPERWORK REDUCTION PROJECT (31500104L OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.
FACILITY NAME (1)
DOCKET NUMBER 42)
LER NUM8ER (6)
PAGE (3) l SEQUENTIAL REVISION Brunswick Steam Electric Plant 05000325 2 of 3 Unit 1 95 01-I TEXT (11 more space is required, use additional l
On January 5, 1995, at 2352 hours0.0272 days <br />0.653 hours <br />0.00389 weeks <br />8.94936e-4 months <br />, a CRD accumulator alarm was received on HCU 18-23.
The HCU had previously been recharged twice that day due to low nitrogen pressure and l
a WR/JO had been initiated to replace the HCU Scram Accumulator Gas Side Isolation I
Valve, C11-111.
A LCO was entered on TS 3.1.3.5.
i On January 6, 1995, at 0126 hours0.00146 days <br />0.035 hours <br />2.083333e-4 weeks <br />4.7943e-5 months <br />, an accumulator alarm was received on HCU 06-39 due to low nitrogen pressure. The HCU was declared inoperable and Technical Specification 3.0.3 was entered due to two HCUs being inoperable. Technical Specification 3.1.3.5 addresses the CRD ECUS and provides action statements for one HCU being inoperable, j
Upon confirmation of the second accumulator low pressure alarm, Technical specification J
3.0.3 was entered.
The HCU was recharged and immediately began losing pressure.
A.
WR/JO was initiated to replace the HCU Scram Accumulator Gas Side Isolation Valve, C11-111.
The valves were replaced on both HCUs (18-23 and 06-39) and the HCUs were returned to service. The HCUs were declared operable and Technical Specification 3.0.3 was exited on January 6,
1995, at 0352 hours0.00407 days <br />0.0978 hours <br />5.820106e-4 weeks <br />1.33936e-4 months <br />.
An investigation was initiated to j
determine the cause of the apparent repetitive failure of the C11-111 valves.
l
CAUSE OF EVENT
The cause of the event is being investigated. The C11-111 valves were disassembled and the 0-rings were shipped to the vendor for evaluation.
The results of the failure 1
evaluation will be used to develop any additional corrective actions needed.
SUPPLEMENTAL INFORMATION:
The most probable cause of the event has been determined by CP&L to be related to the formulation of the elastomeric material comprising the valve body o-rings. The C11-111 valves were disassembled and the 0-rings were shipped off-site for evaluation.
The vendor (from which CP&L procures the subject valves) performed an investigation and concluded that the o-rings were slightly undersized, yet within tolerance, or chemically attacked, resulting in increased potential for leakage.
CP&L's internal findings attributed the degradation of the failed o-rings to improper formulation of the o-ring elastomers. An evaluation performed by CP&L determined that this condition does not constitute a substantial safety hazard nor is it reportable pursuant to 10CFR21. The vendor has received a copy of the CP&L internal report and maintains that these failures are isolated instances.
It is believed that past periodic bulk replacements of these valves with new valves compounded any batch problems with the replacement valves.
I
- - i
(
,U. S. NUCLEAR REGULATORY COMMISSION APPROVED GM8 NO. 3160-0104 I
L-(5/93) _,
EXPIRES: 6/31/96 ESTIMATED BURDEN PER. RESPONSE TO COMPLY WITH THIS j
INFORMATON COLLECTON REQUEST: 50.0 HRS. FORWARO LICENSEE EVENT REPORT (LER)-
COMMEuTS REOARo,No BURDEN ESTIMATE TO THE INFORMATION AND TEXT CONTINUATION RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR j
REGULATORY COMMISSON. WASHINO70N, DC 20665-0001, AND TO i
THE PAPERWORK REDUCTON PROJECT (31500104), OFFICE OF MANAGEMENT AND BUDOET, WASHINGTON, DC 20603.
FACILITY NAME (1)
DOCKET NUMSER (2)
LER NUMSER (6)
PAGE (3) 4 SEQUENTIAL REVISION Brunswick Steam Electric Plant 05000325 3 of 3 Unit 1 95 01
.l TEKT l11 more space is required use additionalNRC form 366A's) (17) i
CORRECTIVE ACTIONS
1.
The C11-111 valves for the two HCUs were replaced.
l 2.
An investigation is underway to address the C11-111 valve failures. The investigation is scheduled for completion on May 31, 1995. This Licensee Event Report will be supplemented by June 30, 1995 addressing the results of the examination and any additional corrective actions.
1 SUPPLEMENTAL INFORMATION AND CORRECTIVE ACTIONS:
The vendor and CP&L have performed investigations to ascertain the cause of the failures. Discussions between CP&L and the vendor relative to long-term resolution of t
the observed o-ring material deficiencies are ongoing.
l 3.
The periodic bulk replacement programs for these valves have been deleted.
l
SAFETY ASSESSMENT
i The safety significance is minimal based on the ability of reactor pressure to scram the control rods. With the reactor at rated pressure, the scram time requirements are met without assistance from the accumulators. The Control Rod Drive System remained available throughout the event, and the rods could have been driven in, if necessary, as a backup.
SUPPLEMENTAL INFORMATION:
An evaluation performed by CP&L determined this condition to not constitute a substantial safety hazard nor to be reportable pursuant to 10CFR21.
_j I
i'
PREVIOUS SIMILAR EVENTS
Previous events involving entry into TS 3.0.3 due to inoperable HCUs were reported in Licensee Event Reports 1-91-015 and 1-91-027.
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EIIS COMPONENT IDENTIFICATION
{
I f
System /Comnonent EIIS Code Control Rod Drive System AA Hydraulic Control Unit AA/HCU Accumulator AA/HCU/ACC I
l 4
}
g-.
Enclosure List of Regulatory Commitments The following table' identifies those actions committed to by Carolina Power &
Light Company in this document.
Any other actions discussed in the submittal represent intended or planned act ons by Carolina Power & Light Company. They are described to the NRC for the NRC's information and are not regulatory
commitments
Please notify the Manager-Regulatory Affairs at the Brunswick Nuclear Plant of any questions regarding this document or any associated.
Commitment
i None.
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