05000321/LER-2014-004-01, Regarding Non-Functional Penetrations Compromise Safe Shutdown Paths in Postulated Fire Event
| ML14336A589 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 12/01/2014 |
| From: | Southern Co, Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-14-1898 LER 14-004-01 | |
| Download: ML14336A589 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 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)(iii) 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3212014004R01 - NRC Website | |
text
Charles R. Pierce Regulatory Affairs Director December 1, 2014 Docket Nos.: 50-321 50-366 Southern Nuclear Operating Company, Inc.
40 Inverness Center Parkway Post Office Box 1295 Birmingham, AL 35242 Tel 205.992.7872 Fax 205.992.7601 U. S. Nuclear Regulatory Commission ATTN : Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant, Units 1 and 2 Licensee Event Report 2014-004-01 SOUT ERN.\\
COMPANY NL-14-1898 Non-Functional Penetrations Compromise Safe Shutdown Paths in Postulated Fire Event Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(ii)(B), Southern Nuclear Operating Company hereby submits the enclosed Licensee Event Report.
This letter contains no NRC commitments. If you have any questions, please contact Greg Johnson at (912) 537-5874.
Respectfully submitted, C. R. Pierce Regulatory Affairs Director CRP/jcm
U. S. Nuclear Regulatory Commission NL-14-1898 Page 2 Enclosures: LER 2014-004-01 cc:
Southern Nuclear Operating Company Mr. S. E. Kuczynski, Chairman, President & CEO Mr. D. G. Bast, Executive Vice President & Chief Nuclear Officer Mr. D. R. Vineyard, Vice President-Hatch Mr. M. D. Meier, Vice President-Regulatory Affairs Mr. D. R. Madison, Vice President-Fleet Operations Mr. B. J. Adams, Vice President-Engineering Mr. G. L. Johnson, Regulatory Affairs Manager-Hatch RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. V. M. McCree, Regional Administrator Mr. R. E. Martin, NRR Senior Project Manager-Hatch Mr. D. H. Hardage, Senior Resident Inspector-Hatch
Edwin I. Hatch Nuclear Plant Licensee Event Report 2014-004-01 Non-Functional Penetrations Compromise Safe Shutdown Paths in Postulated Fire Event
X NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 (02-2014)
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, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Edwin I. Hatch Nuclear Plant Unit 1 05000 321 1 OF 4
- 4. TITLE Non-Functional Penetrations Compromise Safe Shutdown Paths in Postulated Fire Event
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR I SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR Edwin I. Hatch Nuclear Plant Unit 2 05000 366 FACILITY NAME DOCKET NUMBER 05 29 2014 2014 - 004 -
01 12 01 2014
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201 (b)
D 20.2203(a)(3)(i)
D 50.73(a)(2)(i)(C)
D 50.73(a)(2)(vii)
D 1
20.2201(d)
D 20.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A)
D 20.2203(a)(1 )
D 20.2203(a)(4)
~ 50.73(a)(2)(ii)(B)
D 50. 73( a)(2)(vi ii )(B)
D 20.2203(a)(2)(i)
D 50.36(c)(1 )(i)(A)
D 50.73(a)(2)(iii)
D 50. 73(a)(2)(ix)(A)
- 10. POWER LEVEL D 20.2203(a)(2)(ii)
D 50.36(c)(1 )(ii)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
D 20.2203(a)(2)(iii)
D 50.36(c)(2)
D 50.73(a)(2)(v)(A)
D 73.71 (a)(4)
D 100 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii)
D 50.73(a)(2)(v)(B)
D 73.71 (a)(5)
D 20.2203(a)(2)(v)
D 50. 73(a)(2)(i)(A)
D 50.73(a)(2)(v)(C)
D OTHER D 20.2203(a)(2)(vi)
D 50.73(a)(2)(i)(B)
D 50.73(a)(2)(v)(D)
Specify in Abstract below or in
PLANT AND SYSTEM IDENTIFICATION
General Electric-Boiling Water Reactor Estimated burden per response lo comply with lhis mandatory collection requesl: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.
Reported lessons learned are incorporated into the licensing process and led back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and lnlormation Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by internet e-mail to lnlocollects.Resource@ nrc.gov, and to the Desk Olficer, Olfice of Information and Regulatory Affairs, NEOB-10202, (315Q-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMS control number, the NRC may not conducl or sponsor, and a person is not required to respond to, the information collection.
YEAR 2014
- 6. LER NUMBER I
SEQUENTIAL I NUMBER 004 REV NO.
01 2
- 3. PAGE OF 4
Energy Industry Identification System codes appear in the text as (EllS Code XX).
DESCRIPTION OF EVENT
On May 29, 2014, at approximately 1633 EDT, Unit 1 and Unit 2 were operating at 100 percent rated thermal power (RTP) when an analysis was completed by corporate risk informed engineering identifying that both safe shutdown paths were compromised during a postulated fire event. The analysis was performed in light of a discovery that some fire penetration seal configurations do not correspond to a tested configuration. Due to the un-tested configuration of these seals, the penetrations were initially declared non-functional. In their current state, non-tested fire penetration seals result in degraded barriers that could compromise both safe shutdown paths during a postulated fire.
In July 2013, the fire penetration inspection began and starting on 9/13/2013 several penetration seals were identified as potentially non-conforming due to the presence of grout instead of the seal material shown on the design drawings.
Fire watches were established due to the presence of the non-conforming conditions. Work orders were created to repair the affected fire barrier penetration seals to return them to the condition called for by the design drawings.
Upon start of the repair of the affected penetration seals, two were found to contain grout filled 1.5 inches or less into the penetration. In 2014, upon further investigation, some fire penetration seals that were found to have 1.5 inches or less of grout were also found to be in concrete masonry walls that contained hollow cell columns.
The affected penetration seals are located in the Control Building. Two out of three consecutive cell columns in these concrete masonry walls are hollow. The remaining cell is filled with grout which is non-shrinkable. SNC calculations conclude that most walls in the control building exceed the requirements for even the heaviest of aggregates for a 3 hour3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> fire rating. However the initial review of fire penetrations that are in hollow columns, with 1.5 inches of grout seal, concluded that this "as found" condition did not meet a configuration that had been tested and therefore was assessed as not meeting 10 CFR 50 Appendix R requirements. Fire testing was subsequently performed at an independent laboratory of the "as-found" condition at Hatch Nuclear Plant. This testing concluded that the grout penetration seals in the hollow block walls would be able to maintain a 3-hour fire rating and meet Appendix R requirements. It was therefore assessed that functionality of the fire penetrations through the hollow block walls containing grout as the sealant material was maintained and the "as-found" condition would not impact both safe shutdown paths.
CAUSE OF EVENT
The cause of the event is attributed to not maintaining adequate configuration control of the fire penetration seals through hollow walls and the lack of testing results that would address the plant configuration for the penetration seals. The point at which this occurred could not be determined and was considered a legacy issue. As previously discussed, subsequent testing was successfully performed and demonstrated that the "as found" condition of the penetration seals in question ensures a 3-hour fire rating is maintained as required by 1 OCFR50, Appendix R.
Current processes will ensure that the configuration of the penetrations through hollow block walls will be maintained. (02-2014)
- 1. FACILITY NAME Edwin I. Hatch Nuclear Plant Unit 1 U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE OF YEAR I SEQUENTIAL I REV NUMBER NO.
05000 321 3
4 2014 004 01 REPORT ABILITY ANALYSIS AND SAFETY ASSESSMENT Since the vulnerability described could result in a condition such that the required degree of separation for redundant safe shutdown trains would be adversely impacted, this event represents an unanalyzed condition that significantly degrades plant safety and is reportable in accordance with 10 CFR, Part 50.73(a)(2)(ii)(B).
Upon observation of the "as found" configuration of 1.5 inches of grout, or less, used to seal the penetrations of the hollow block walls, it was assessed that the seals were non-conforming and the penetrations did not currently meet Appendix R requirements. This configuration represented a degraded condition, since the use of grout in this manner did not constitute a tested configuration. As part of planned corrective actions, fire testing at an independent laboratory was performed to evaluate the fire resistance capabilities of grouted penetrations in hollow block walls.
Each test wall assembly consisted of a number of grouted penetrations, thus representing the "as-found" details within Hatch Nuclear Plant. The resulting evaluation report assessed the fire test results, their conformance to regulatory requirements, and provided specific evaluation of the maximum unexposed temperatures of the assembly using the guidance in Generic Letter 86-10. The test assemblies were evaluated in accordance with American Society for Testing and Materials (ASTM) E814-83 Standard for an F-rating (Fire). A further review was also conducted to ensure the potential for ignition of combustible material on the non-exposed ("cold") side of the penetration, walls adjacent to the hollow concrete masonry walls, was minimized. A recommendation was made to establish administrative controls to prevent the storage of combustible materials adjacent and in contact with the walls for particular fire zones. This additional fire protection feature minimizes risks and provides a margin of error for combustible loading on the adjacent walls. These administrative controls will ensure that material is not in direct contact with any penetrating items (conduit or piping) within 12 inches of the wall.
All of the tested "as-found" penetration seal configurations achieved a 3-hour F-rating. The penetrations details maintained unexposed side temperatures below the self-ignition temperature of cable insulation. It was therefore assessed that the fire penetrations through the hollow block walls containing grout as the sealant material meet Appendix R requirements as a 3-hour barrier and would not impact both safe shutdown paths. Due to this assessment, this event does not represent an unanalyzed condition that would significantly degrade plant safety for these grouted penetrations. Similar conditions of non-functional fire penetrations affecting both safe shutdown paths for two additional penetrations were identified as part of the "extent of condition" inspections that will be provided in an update report upon completion of the penetration inspection activity. The presence of the fire wall in which the penetrations are located, although degraded, also continued to provide a barrier in conjunction with defense in depth measures that include adequate compensatory measures, fire detection and fire suppression systems. These engineered features, compensatory measures and resultant testing conclusion of the grout penetration seals in the hollow block walls provide sufficient reassurance that in the event of a postulated fire, there will be adequate time for the response of the station fire brigade to take appropriate actions to mitigate the consequences of a fire to ensure at least one safe shutdown path is preserved. This is a postulated event and as such did not adversely affect the safe operation of the plant or the safety of the public. The actual safety impact of this condition has very low safety significance.
CORRECTIVE ACTIONS
As part of an extent of condition, all fire penetrations are being inspected to evaluate their "as-found" condition. Fire actions have been taken as required for the two additional penetrations and will be taken as required for any additional non-conforming penetrations identified during the course of the inspection activity that is scheduled to complete by 12/31 /2014. Any additional corrective actions due to non-functional fire penetrations affecting both safe shutdown paths will be provided in a final supplemental report. Administrative controls will be put in place to increase defense-in-depth and ensure material is not in direct contact with any penetrating items (conduit or piping) within 12 inches of the wall for particular fire zones. Fire watches were established as compensatory measures during the planned testing of the "as found" configuration of the penetrations and will continue as required until the appropriate administrative controls are in place.
RC FORM 366A (02-2014) (02-2014)
U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET Edwin I. Hatch Nuclear Plant Unit 1 05000 321
ADDITIONAL INFORMATION
Other Systems Affected: None
Failed Components Information
Master Parts List Number: Multiple Fire Barrier Penetrations Manufacturer: N/A Model Number: N/A YEAR 2014
- 6. LER NUMBER I
SEQUENTIAL I REV NUMBER NO.
004 01 EllS System Code: NA Reportable to EPIX: Y Root Cause Code: X 4
Type: Fire Barrier Penetration Manufacturer Code: N/A EllS Component Code: PEN Commitment Information: This report does not create any licensing commitments.
PREVIOUS SIMILAR EVENTS
None RC FORM 366A (02-2014)
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