ML20107D030
| ML20107D030 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 04/15/1996 |
| From: | Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 96-160, NUDOCS 9604180106 | |
| Download: ML20107D030 (5) | |
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VIRGINIA ELECTRIC AND PownN COMI*ANY Ricituoxo,VinorxrA 20201 April 15, 1996 i
U. S. Nuclear Regulatory Commission Serial No.96-160 Attention: Document Control Desk NAPS /MPW/MAE R4 Washington, D. C. 20555 Docket Nos.
50 338 50-339 License Nos.
NPF-4 NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 INSPECTION REPORT NOS. 50-338/96-01 AND 50-339/96-01 REPLY TO A NOTICE OF VIOLATION We have reviewed your letter of March 21,1996, which referred to the inspection conducted at North Anna Power Station from January 14 through February 24,1996, and the associated Notice of Violation which was reported in Inspection Report Nos.
50-338/96-01 and 50-339/96-01. Our reply to the Notice of Violation is attached.
If you have any further questions, please contact us.
Very truly yours, James P. O'Hanlon Senior Vice President - Nuclear Attachment cc:
U. S. Nuclear Regulatory Commission Region ll 101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323 Mr. R. D. McWhorter NRC Senior Resident inspector North Anna Power Station 9604180106 960415 PDR ADOCK 05000338 O
PDR I
REPLY TO A NOTICE OF VIOLATION INSPECTION REPORT NOS. 50-338/96-01 AND 50-339/96-01 NRC COMMENT During an NRC inspection conducted on January 14 through February 24,1996,a violation of NRC requirements was identified.
In accordance with the " General Statement of Policy and Procedure for NRC Enforcement Actions," NUREG 1600, the violation is listed below:
10 CFR 50, Appendix B, Criterion Ill, as implemented by Operational Quality Assurance Program Topical Report VEP-1-5A, Updated Final Safety Analysis Report Section 17.2.3, Design Control, collectively require that measures be established to assure that applicable regulatory requirements and the nuclear power station design bases are correctly translated into the company specifications, drawings, procedures, and inswetions amlicable to modifications.
Contrary to the above, on February 13,1996, it was identified that six blowout panels for both units' incore instrument tunnels had been modified by installing hasps and locks without appropriate design j
controls. Additionally, several containment cubicle door panels had been modified by tack welding their sheet metal covers.
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modifications were not reviewed prior to installation to assure their 3
compliance with design bases assumptions contained in the Updated l
Final Safety Analysis Report, sections 6.2.1.3.2.3 and 6.2.1.3.2.5, and i
existed for an extended time period during the past operating cycles.
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This is a Severity Level IV violation (Supplement 1).
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1 REPLY TO NOTICE OF VIOLATION 1.
REASON FOR THE VIOLATION The reason for tb violation was a failure to recognize that modifications made to the steam generator and pressurizer cubical doors and the incore i
instrumentation tunnel were modifications that affected safety features
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described in the UFSAR.
The UFSAR describes the blowout panels for the steam generator and pressurizer cubical doors as " blowout sheet metal panels fastened by six sheet metal screws to the frame of a locked wire grid door." The UFSAR also states that these blowout panels are designed to blow out at 2.5 psid.
As a result of repeated failures of the sheet metal screws, the blowout panels were stitch welded to the door frames of the steam generator and pressurizer cubicles. In addition, the latching mechanism on the pressurizer cubicle door had been removed. These changes invalidated the description in the UFSAR.
The UFSAR describes six blowout panels in the incore instrumentation tunnel access housing that are attached by hinges and closed during normal operation. These blowout panels are displaced by a pressure differential of 0.25 psid to allow air flow from the incore instrumentation tunnel to the containment during a design basis accident.
The Unit 1 incore instrumentation tunnel blowout panels were discovered locked closed (i.e., hasp vv. sided to frame and padlocked) during the recent Unit 1 refueling outage. T hese locks were installed, approximately 15 years ago, to prohibit unauthorized access into a very high radiation area following sovaral industry overexposures in the area beneath the reactor vessel. (Reference Information Notice issued by the NRC, IEIN 82-51, Overexposures in PWR Cavities.)
2.
CORRECTIVE STEPS WHICH HAVE BEEN TAKEN AND THE RESULTS ACHIEVED The Unit 1 steam generator cubical doors were restored to their original design configuration (i.e., the welds on the blowout panels were ground off and the blowout panels were attached to the door frames with six sheet metal screws) during the recent refueling outage. A structural evaluation was performed to determine if the welded blowout panels would be displaced during accident conditions. A pressure differential of 2.5 psid was used and a configuration of two inch welds every twelve inches around the perimeter of the doors was assumed. This weld configuration is more conservative than the as-found condition. It was determined that the welded blowout paneis on the e'eam generator cubical doors would not have caused the steam generator cubict to become over pressurized.
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e As previously discussed, the latching mechanisms on the pressurizer cubicle doors on Units 1 and 2 were found to be removed. Therefore, the pressurizer cubical doors will now open with a much lower pressure differential than the 2.5 psid discussed in the UFSAR. The existing configuration of the pressurizer cubical doors meets the design basis requirements for the blowout panels.
1 Therefore, no changes will be made to the Unit 1 and 2 pressurizer cubicle coors or their associated blowout panels.
l After the identification of the Unit 1 incore instrumentation tunnel blowout panels being locked closed, a containment entry was made to remove the locks on the Unit 2 incore instrumentation tunnel blowout panels. This action restored the functionality of the blowout panels to their original design configuration.
During the Unit 1 refueling outage, the inccre instrumentation tunnel blowout panels were functionally tested. Bars were installed on the inside of the blowout panel frames which allowed the removal of the locks, while still preventing unauthorized entry.
An evaluation was done to determine the pressure at which the hasps on the incore instrumentation tunnel blowout panels would have failed. The maximum i
equivalent failure pressure of the hasps removed from containment was 2.4
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psid. However, the 2.4 psid equivalent failure pressure of the hasps exceeds the UFSAR displacement pressure of 0.25 psid.
I Therefore, an evaluation was performed to determine the effect of the delayed blowout panel opening on the incore instrumentation tunnel subcompartment analysis. The evaluation determined that the pressure differential experienced i
in the incore instrumentation tunnel during a design basis accident would be
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approximately equal to the opening pressure differential for the blowout panels.
Had a design basis accident occurred while the locks were installed on the blowout panels,. the blowout panels would have opened before the subcompartment pressure exceeded the incore instrumentation tunnel design i
criteria.
This event was discussed with station personnel during a recent Human Performance Stand Down Day.
3.
CORRECTIVE STEPS WHICH WILL BE TAKEN TO AVOID FURTHER VIOLATIONS As previously discussed, it was determined that the welded blowout panels on the steam generator cubical doors would not have caused the steam generator cubicles to become over pressurized. However, the Unit 2 steam generator cubical doors will be restored to their original design configuration and bars will be installed on the inside of the Unit 2 incore instrumentation tunnel blowout panel frames during the next refueling outage, which is currently scheduled for i
September 1996.
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l UFSAR changes have been initiated to revise the description of the pressurizer cubical doors and the incore instrumentation tunnel blowout panels, as well as addresses the recent modifications to the incore instrumentation tunnel blowout panel frames.
The Augmented Inservice Inspection Manual will be revised to properly inspect the incore instrumentation tunnel blowout panels.
A Training Information Bulletin will be issued to all nuclear personnel emphasizing the importance of ensuring UFSAR compliance when performing all types of maintenance and design changa activities.
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THE DATE WHEN FULL COMPLIANCE WILL BE ACHIEVED Full compliance has been achieved.
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