05000346/LER-2006-004, Potential Damage to Ventilation Dampers Due to Design-Basis Tornado Differential Pressures
| ML070450138 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 02/12/2007 |
| From: | Bezilla M FirstEnergy Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NP-33-06-004-00 LER 06-004-00 | |
| Download: ML070450138 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii) 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 |
| 3462006004R00 - NRC Website | |
text
FENOC "W%5501 North State Route 2 FirstEnergy Nuclear Operating Company Oak Harbor, Ohio 43449 Mark B. Bezilla 419-321-7676 Vice President - Nuclear Fax: 419-321-7582 Docket Number 50-346 NP-33-06-004-00 10 CFR 50.73 License Number NPF-3 February 12, 2007 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-0001 Licensee Event Report 2006-004-00 Potential Damage to Ventilation Dampers due to Design-Basis Tornado Differential Pressures Davis-Besse Nuclear Power Station, Unit No. 1 Date of Occurrence - December 14, 2006 Ladies and Gentlemen:
Enclosed please find Licensee Event Report (LER) 2006-004-00, which is being submitted to provide written notification of the discovery that some safety-related ventilation dampers could have been damaged due to design-basis tornado differential pressures. This issue is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B) as operation or condition prohibited by the Technical Specifications, and 10 CFR 50.73(a)(2)(vii) as a single cause that caused at least one independent train to become inoperable in multiple systems. Commitments associated with this LER are listed in the Attachment.
The evaluation of the safety significance of this issue has not been formally completed. This information will be provided in a Supplement to this LER as detailed in the attached
commitments
Very truly yours, GMW Attachment Enclosure cc:
Regional Administrator, USNRC Region III DB-1 Project Manager, USNRC DB-1 NRC Senior Resident Inspector Utility Radiological Safety Board
Docket Number 50-346 License Number NPF-3 NP-33-06-004-00 Attachment Page 1 of 1 COMMITMENT LIST The following list identifies those actions committed to by the Davis-Besse Nuclear Power Station in this document. Any other actions discussed in the submittal represent intended or planned actions by Davis-Besse. They are described only as information and are not regulatory
commitments
Please notify the Manager - Regulatory Compliance (Acting) (419-321-7120) at Davis-Besse of any questions regarding this document or associated regulatory commitments.
COMMITMENTS
DUE DATE
- 1. Revise procedures to protect Component Cooling Water Pump Room and Low Voltage Switchgear Room ventilation dampers from tornado differential pressures.
- 2. Update the DBNPS Design Criteria Manual to add a statement that safety-related ventilation systems and their components must be designed for applicable design basis tornado differential pressures.
- 3. Update the Design Interface Review Checklist to ensure personnel performing design interface evaluations properly address tornado differential pressure loads that may affect safety-related ventilation systems.
- 4. Submit supplemental information regarding the safety significance of this occurrence.
- 1. Completed on January 26, 2007, by issuance of Revision 06 of procedure RA-EP-02810, "Tornado."
- 2. May 31, 2007
- 3. May 31, 2007
- 4. April 30, 2007
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 6/30/2007 (6-2004)
, 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 Davis-Besse Unit Number 1 05000346 1 OF 5
- 4. TITLE Potential Damage to Ventilation Dampers due to Design-Basis Tornado Differential Pressures
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED M
F SEQUENTIAL REV r FACILITY NAME DOCKET NUMBER YMONTH DAY YEAR IEo NUMBER N
MONTH DAY YEAR 05000 12 14 2 00 6* 2006 004+
00 1 02 12 0 07.
05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
El 20.2201(b)
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20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
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Li 50.73(a)(2)(iii)
El 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL
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[] 50.36(c)(1)(ii)(A)
Li 50.73(a)(2)(iv)(A)
Li 50.73(a)(2)(x)
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Li 50.36(c)(2)
Li 50.73(a)(2)(v)(A)
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Li OTHER Specify in Abstract below Li 20.2203(a)(2)(vi)
Z 50.73(a)(2)(i)(B)
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ANALYSIS OF OCCURRENCE:
This issue involves only the ventilation systems of the LVSGR and CCW Rooms. The equipment within these rooms is expected to be able to operate for some period of time following a tornado event before room temperatures reach a point where equipment operation is adversely affected. There should be sufficient time for a high temperature condition to be diagnosed and corrected using existing and/or portable ventilation equipment following the tornado event. Therefore, it is believed this event had minimal safety significance. A more detailed analysis of the effects of the loss of ventilation in the LVSGR and CCW Rooms is underway, and the results of this analysis will be reported in a supplement to this report.
CORRECTIVE ACTIONS
Under an Operability Evaluation, it was determined that the LVSGR dampers would remain operable in the event of a tornado provided the room intake dampers, and the exhaust damper for LVSGR 2, were open prior to a tornado. A Standing Order was issued to start the LVSGR Fans and ensure these dampers were opened and then open the supply breakers for the dampers upon issuance of a Tornado Watch to keep the dampers in the open position. Similar measures were incorporated into revision 06 of procedure RA-EP-02810, "Tornado," on January 26, 2007.
Under another Operability Evaluation, it was determined that the CCW Room inlet louvers would remain operable in the event of a tornado provided the louvers were open prior to a tornado. A Standing Order was issued to open the louver supply breakers, thereby failing open the louvers to maintain them in the open position, upon issuance of a Tornado Watch. These compensatory measures were incorporated into revision 06 of procedure RA-EP-02810, "Tornado," on January 26, 2007.
The DBNPS Design Criteria Manual will be updated to add a statement that safety-related ventilation systems and their components must be designed for applicable design basis tornado differential pressures. Also, the Design Interface Review Checklist will be updated to ensure that personnel performing design interface evaluations as part of engineering activities properly address tornado differential pressureloads that may affect safety-related ventilation systems.
FAILURE DATA:
There have been no Licensee Event Reports at the DBNPS involving the effects of tornado differential pressures in the past three years. A recent question regarding the effects of tornado depressurizations, raised as a result of a NRC Inspection of Evaluation of Changes, Tests, of Experiments and Permanent Plant Modifications completed in March 2006, was the basis for including the effects of tornado differential pressure in the engineering self-assessment to prepare for the upcoming NRC Component Design Basis Inspection.
Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
NP-33-06-004-00 CRs 2006-11269, 2006-11421, 2006-11483, 2006-11740