05000280/LER-2010-002, Regarding Use of Aluminum Conduits for Cable Penetrations Degrades Fire Barriers
| ML102230420 | |
| Person / Time | |
|---|---|
| Site: | Surry  (DPR-032, DPR-037) |
| Issue date: | 08/02/2010 |
| From: | Gerald Bichof Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 10-442 LER 10-002-00 | |
| Download: ML102230420 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2802010002R00 - NRC Website | |
text
1 OCFR50.73 Virginia Electric and Power Company Surry Power Station 5570 Hog Island Road Surry, Virginia 23883 August 2, 2010 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555-0001 Serial No.:
SPS:
Docket No.:
License No.:
10-442 JSA 50-280 50-281 DPR-37
Dear Sirs:
Pursuant to 10CFR50.73, Virginia Electric and Power Company hereby submits the following Licensee Event Report applicable to Surry Power Station Units 1 and 2.
Report No. 50-280, 50-281/2010-002-00 This report has been reviewed by the Station Facility Safety Review Committee and will be forwarded to the Management Safety Review Committee for its review.
Very truly yours, Gerald T. Bischof, Site Vice President Surry Power Station Enclosure Commitment contained in this letter: None
~LrL
cc: U.S. Nuclear Regulatory Commission, Region II Marquis One Tower 245 Peachtree Center Ave., NE, Suite 1200 Atlanta, GA 30303-1257 NRC Senior Resident Inspector Surry Power Station
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY IMB: NO. 3150-0104 EXPIRES 08/31/2010 (9-2007)
, the NRC may (See reverse for required number of not conduct or sponsor, and a person is not required to respond to, the digits/characters for each block) information collection.
- 3. PAGE Surry Power Station 05000- 280 1 OF 5
- 4. TITLE Use of Aluminum Conduits for Cable Penetrations Degrades Fire Barriers
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE 1
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACII.ITY NAME n-,CKFT N1IMRFR MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR Surry Power Station, Unit 2 05000 - 281 FA(IIITY NAME DOC'KET NHMRF-R 06 04 10 2010-002 -
00 08 02 10 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR.: (Check a// that apolv) 1:1 20.2201(b)
F] 20.2203(a)(3)(i)
U 50.73(a)(2)(i)(C) 50.73(a)(2)(vii)
N LI 20.2201(d)
E]
20.2203(a)(3)(ii)
LI 50.73(a)(2)(ii)(A)
[] 50.73(a)(2)(viii)(A)
LI 20.2203(a)(1)
[]
20.2203(a)(4).
[j 50.73(a)(2)(ii)(B)
[]
50.73(a)(2)(viii)(B) 20.2203(a)(2)(i)
L] 50.36(c)(1)(i)(A)
[J 50.73(a)(2)(iii)
[] 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL LI 20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(,)
50.73(a)(2)(iv)(A) f] 50.73(a)(2)(x)
EL 20.2203(a)(2)(iii) 50(.36(c)(2)
.50.73(a)(2)(v)(A)
L] 73.71(a)(4) 100%
LI 20.2203(a)(2)(iv)
EJ 50.46(a)(3)(ii)
LI 50.73(a)(2)(v)(B)
LI 73.71(a)(5)
EL 20.2203(a)(2)(v)
EL 50.73(a)(2)(i)(A)
[]
50.73(a)(2)(v)(C)
[] OTHER r-i Specify in Abstract below El 20.2203(a)(2)(vi)
[]
50.73(a)(2)(i)(B)
L.
50.73(a)(2)(v)(D) or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER FACILITY NAME TELEPHONE NUMBER (include Area Code)
B. L. Stanley, Director Safety and Licensing (757) 365-2003CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE C
FACTURER TO EPIX FACTURER TO EPIX B
MF PEN N/A N
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH.
DAY YEAR E] YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
[] NO SUBMISSION DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
During the June 2009 Tri'ennial Fire Protection Inspection, the NRC requested test results for aluminum conduits used in fire barrier penetrations. The testing documentation could not be produced. The fire barriers in question were declared non-functional and a condition report was initiated. Compensatory actions involved establishing fire watches for the non-functional barriers. A vendor was selected to test representative aluminum conduit configurations in fire barriers in accordance with IEEE 634-1978. Several configurations failed the 3-hour fire test. A design change was developed to modify penetrations that did not have proven test configurations, by installing seals on both side of the barrier. Since the modified aluminum conduit penetrations did not have proven test configurations, their function of preventing a fire from affecting redundant trains of safe shutdown systems could not be assured. NRC guidance for reportability, NUREG-1022, states missing fire barriers, such that the required degree of separation for redundant safe shutdown trains is lacking, is reportable as an unanalyzed condition that significantly degraded plant safety. Therefore, this report is being submitted pursuant to 10CFR50.73(a)(2)(ii)(B).
1.0 DESCRIPTION OF THE EVENT The Surry NRC Triennial Fire Protection Inspection was initiated on June 8, 2009.
During performance of the inspection, the NRC inspectors requested documentation that aluminum conduits used for Appendix R wall and floor fire barrier penetrations seals [EIlS-IC-PEN] were qualified to a 3-hour fire rating. Documentation was available for steel conduits, steel cable trays, and aluminum cable trays that penetrate fire barriers. Test reports were not available for the aluminum, conduit penetrations. The concern was that the aluminum conduit would melt at the flame temperature used during fire testing and if not properly sealed internally, flame and smoke may pass through the barrier.
The Surry specification for the installation, inspection, and documentation of silicone foam in fire barrier penetrations was issued in 1978 and provided guidance for foam installation. It requires that all conduits that penetrate the control room pressure envelope or penetrate fire area boundaries and terminate at a distance up to 5 feet from the barrier are to be foamed internally. Also, station electrical maintenance procedures for opening and sealing of fire barriers required that conduits be internally foamed to a depth of 10 inches with at least part of the foam contained within the wall or floor. The internal foam would provide a seal to prevent passage of hot gasses and smoke through the penetration in the event of an Appendix R fire.
Conduit penetrations foamed internally to these requirements were considered acceptable.
In 1990 and 1991, Surry developed a Fire Penetration Seal Evaluation Program in response to Information Notice (IN) 88-04 and IN 88-04 Supplement 1, Inadequate Qualification and Documentation of Fire Barrier Penetration Seals. The numbers of penetrations not meeting the 3-hour fire rating were identified and repairs recommended. The scope of the program included identification and repair of conduit internal seals. Repairs were completed during unit outages in 1994.
However, the documentation for these repairs was not adequate to ensure compliance with the 3-hour fire rating for aluminum conduit penetrations.
Following the 2009 Triennial Fire Protection Inspection, a condition report was initiated and corrective actions were assigned to establish a valid qualification package for the aluminum conduit penetration configurations. A walkdown of accessible penetration areas (approximately 90% of penetrations) was conducted and an evaluation of drawings was performed to determine the various configurations where aluminum conduits penetrate fire barriers. Approximately 460 aluminum conduit penetrations were identified for both Surry Unit 1 and Unit 2. Three aluminum conduit configurations were identified and an evaluation determined the internal foam installation on two of the configurations may not be adequate. These fire barriers were declared non-functional and a condition report was initiatedU. S. NUCLEAR REGULATORY COMMISSIONU. S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REV YEAR NUMBER NO.
Surry Power Station 05000-280 3 of 5 2010 002 00 documenting the possible fire barrier impairments. Compensatory actions involved establishing fire watches for the non-functional barriers as required by Surry's Technical Requirements Manual.
A vendor was selected to test the aluminum conduit configurations. Test slabs were constructed and penetration configurations were assembled at the vendor facility.
Testing was completed and test repoirts provided to Surry Engineering.
An evaluation of the vendor test reports indicated that several aluminum conduit configurations did not meet the established test criteria. Aluminum conduit configurations with internal seals provided on both sides of the inside plane of the fire barrier passed the fire testing, whereas some configurations with conduit internal seals provided on only one side of the inside plane of the fire barrier and those without internal seals did not pass the testing.
With fire barrier penetrations specifications in place and significant repairs completed on penetrations in the 1990's, there was a reasonable expectation that the fire barriers could perform their function. However, due to the lack of documentation and the identification of aluminum conduit penetrations configurations where internal foam installation could not be confirmed, further evaluation or modifications were needed to ensure compliance. A design change was developed to accept the aluminum conduit penetrations based upon the proven test configuration, to evaluate the penetrations as satisfactory using Generic Letter (GL) 86-10 as guidance, or to modify the penetrations by installing smoke seals or silicone foam seal on both side of the barrier.
Aluminum conduit penetration configurations that do not have proven test configurations will be modified by installing smoke seals or silicone foam seals on both sides of the barrier. Since the modified aluminum conduit penetrations did not have proven test configurations, it wasiassumed that their function of preventing a fire from affecting redundant trains of safe shutdown systems could not be assured.
NRC guidance on reportability, NUREG-1022, Event Reporting Guidelines for 1 OCFR50.72 and 50.73, rev. 2, states that if fire barriers are missing, such that the required degree of separation for redundant safe shutdown trains is lacking, the issue is reportable as an unanalyzed condition that significantly degraded plant safety. Therefore, this report is being submitted pursuant to 10CFR50.73(a)(2)(ii)(B),
documenting the degraded fire barriers.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS
Safe shutdown would be maintained, as described in the Appendix R Report, for fires in the fire areas affected by the aluminum conduit penetration issue. The bounding testing performed demonstrated that there existed sufficient time for detection and suppression to mitigate a fire prior to expected damage outside of the given fireU. S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REV YEAR NUMBER I
NO.
Surry Power Station 05000 - 280 4 of 5 2010 002 00 areas. Prompt fire brigade response, the existing fire barriers, and fire suppression and detection systems, where applicable, would preserve safe shutdown capability.
Based on this, the change in Core Damage Probability for the aluminum conduit deficiency would be low. This situation has not resulted in any significant safety consequences or implications and the health and safety of the public were not affected at any time.
3.0
CAUSE
The apparent cause evaluation determined that the effects of fire on aluminum conduits were not originally considered when the fire testing packages were compiled for Surry. The packages addressed steel conduit and aluminum cable trays penetrations but did not document aluminum conduits in fire barriers.
4.0 IMMEDIATE CORRECTIVE ACTION(S)
Upon identification of the fire barrier impairments, a station condition report.was issued and, in accordance with the Surry Technical Requirements Manual, fire watches were established as required.
5.0 ADDITIONAL CORRECTIVE ACTIONS
Vendor testing of various configurations of aluminum conduit penetrations in fire barriers was completed using IEEE 634-1978, "Standard Cable Penetration Fire Stop Qualification Test", as the basis for the testing.
The procedure used for opening and sealing fire barriers was revised to prohibit the use of aluminum conduit through Appendix R fire barriers. In addition, the station design specification for electrical installation will be revised to prohibit the use of aluminum conduits through Appendix R fire barriers.
A design change was developed to accept the aluminum conduit penetrations based upon the proven test configuration, to evaluate the penetrations as satisfactory using Generic Letter (GL) 86-10 as guidance, or to remediate the penetrations by installing smoke seals or silicone foam on both sides of the barrier.
6.0 ACTIONS TO PREVENT RECURRENCE The design change to modify penetrations that do not have proven test configurations is currently being implemented. The design change is scheduled to be completed in 2010.U, S. NUCLEAR REGULATORY COMMISSION (9-2007)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE SEQUENTIAL REV YEAR NUMBER NO.
Surry Power Station 05000-280 5 of 5 2010 002 00
7.0 SIMILAR EVENTS
None 8.0 MANUFACTURER/MODEL NUMBER None
9.0 ADDITIONAL INFORMATION
Unit 1 and Unit 2 were at 100% reactor power during the inspection.