ML20136H849
| ML20136H849 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 11/19/1985 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8511250211 | |
| Download: ML20136H849 (3) | |
Text
,.
k DUKE POWER GO3 mon-P.O. HO X 3 310 0 CHARLOTTE, N.C. 28242 IIAL II. TIJCKER Trs.rruoxe vmm enseman, (704) 373-4531 maanan emone enom November 19, 1985 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regualtion U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Ms. E. G. Adensam, Chief Licensing Branch No. 4
Subject:
McGuire Nucicar Station Docket Nos. 50-369 and 50-370 Safety Justification for Operation without Upgrading the Pressurizer Relief Tank Sightglass
Dear Mr. Denton:
In your letter of September 24, 1985 addressed to H. B. Tucker, it is stated that additional justification is necessary for the NRC approval of the deletion of a Duke Power committment to upgrade the pressurizer Relief Tank sightglass in McGuire Nuclear Station Units 1 and 2.
Duke Power has completed the following evaluation in response to your request and has concluded that no significant safety concern exists if the present UHI fill and vent configuration and sight-glass is maintained.
In Licensee Event Report 370/85-10 dated June 26, 1985, Duke Power stated that the Pressurizer Relief Tank sightglass on both Units would be replaced with a sightglass that has higher pressure and temperature limits. Due to the antici-pated deletion of the Upper Head Injection (UHI) system (proposed in my letter of May 9,1985), the above modifications were determined to be no longer needed since the primary cause of the sightglass failures has been personnel errors and/or hardware problems associated with the UHI fill and vent procedure.
Experience related to UHI fill and vent incidents has involved only minor leakage (up to 5 gpm) from the sightglass and other venting related components.
A conservative maximum leak rate caused by the failuru of the sightglass or nearby piping is approximately 100 gpm during conditions associated with the UHI fill and vent procedure and isolation valves fully open. As shown by FSAR Figure 6.3.2-7 (charging pump head curve), even the maximum hypothetical leak could easily be compensated for by the charging pump required by Technical Specification during the UHI fill and vent procedure.
Since the sightglass and Upper Head Vent System piping is isolatabic from tne RCS pressure boundary, the failures do not constitute a challenge to ar.y of the fission product boundaries. Therefore, no significant safety cancern exists if the present UHI fill and vent configuration and sightglass is maintained.
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Mr. Harold R. Denton, Director November 19, 1985 Page 2 The sightglass failures do pose a potential hazard to personnel working in containment and Duke has taken appropriate actions to minimize the risk to these personnel. Additional training and procedures to ensure proper valve positions during the Util fill and vent procedure were provided to address possible leakage through UHI/RCS isolation valves due to improper seating.
Isolation valves have been clearly labeled to prevent personnel from mistakenly opt ing the wrong valve during the UHI fill and vent procedure as was discussed in LER 370/85-10. The implementation of procedural and physical changes minimizes the risk of challenges to the sightglass design linits.
In the case that delays in NRC review of the UllI deletion submittals impact current modifi-cation schedules, an evaluation of the sightglass upgrade and addition of isolation valves may be performed.
Current plans call for removal of UllI during the Unit 1 1986 refueling outage and Unit 2 1987 refueling outage.
In containment survey work will also be performed during the 1986 outages to allow adequate planning for relocation of the sightglass and isolation valve used to vent the RCS. This modification is planned to be performed during the 1987 outages in order to simplify the RCS venting operation.
It should be recognized that the survey work is required for Upper llead Vent System modifications whether UHI is deleted or not and thus the 1987 refueling outages would be the earliest schedule for upgrading the sightglass if NRC approval for deletion of the UllI System is delayed.
Based upon the preceeding evaluation, Duke Power has determined that if the existing UllI fill and vent configuration is maintained:
1.
No significant plant safety concern is introduced; and 2.
No significant hazard to personnel working in containment is introduced due to additional training, procedural, and physical changes implemented b, Duke Power.
Since the risk of additional sightglass failures has been minimized through procedural and physical changes, the sightglass no longer needs to be upgraded.
This commitment should therefore be deleted.
Picase feel free to contact us if you require any additional information.
Very truly yours, paux Ital B. Tucker JGT/hrp u.
Mr. liarold R. Denton, Director November 19, 1985 Page 3 cc Dr. J. Nelson Grace, Regional Administrator U. S. Nucicar Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 Mr. W. T. Orders NRC Resident Inspector McGuire Nucicar Station l
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