ML19350B179
| ML19350B179 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 03/11/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19350B176 | List: |
| References | |
| NUDOCS 8103200051 | |
| Download: ML19350B179 (2) | |
Text
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~A UNITED STATES
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NUCLEAR REGULATORY COMMISSION e
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WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION, UNIT NO. 2 DOCKET NO. 50 339
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Introduction:==
During the NRC staff (the staff) review of the Amplified Response Spectra Analysis for the North Anna Power Station, Unit No. 2 (NA-2), a potential problem was noted regarding excessive deformation of the Low Head Safety Injection (LHSI) pump shaft due to containment wall expansion during a Loss-Of-Coolant Accident (LOCA).
By letter, dated November 5, 1980 the staff reyucsted that the Virginia Electric and Power Company (the licensee) provide additional information so that the relative icportance of this potential problem could be accurately determined. Also, the staff request for information noted that the Outside Recirculation Spray (0RS) pumps proximity to the containment wall might be affectea in a similar manner as noted above for the LHSI pump shaft.
Discussion:
Soth the LHSI and ORS pumps at NA-2 are similarly constructed and installed.
Therefore', this discussion applies to both pumps.
The licensee's calculated containment radial growth, at the pump lateral wponrt elevation of 257 degrees - 10 minutes, relative to the containment mat, is 0.98 inches. The effect of this relative ccm ainment movement on the ability of either the LHSI pumps of the ORS pump, start and operate successfully is deemed to be negligible. The deflect- - if 0.98 inches is taken over the length of the pump, between its upper seismic restraints and lower seismic guides (approx-imately 520 inches).
The overall angle created by this deflection is less than six minutes of arc.
Such a deflection is not great enough to prevent the pump from starting or cause measurable bushing wear, and the load carrying capability of the bushings will not be exceeded by this deflection.
Also, for the short period of time involved (less than is hour) it is reasonable to expect that negligible wear will be accumulated on bushings due to the containment deflection.
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Conclusion:
The staff concludes that the licensee's evaluation with regard to the consequences of relative containment movement of 0.93 inches on the cperability of LHSI and ORS pumps is acceptable. Also, because of the short time involved in the above postulated event, it is reasonable to expect that pump cperability will not be adversely affected due to the flexibility of the pump shaft and the ability of the column bushings to sustain the applied loading. Therefore, the staff considers this matter resolved.
Date: March 11, 1981 4
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