ML20128A558

Safety Evaluation Supporting Amends 173 & 172 to Licenses DPR-32 & DPR-37,respectively

ML20128A558
Person / Time
Site:	Surry
Issue date:	01/22/1993
From:	Office of Nuclear Reactor Regulation
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Shared Package
ML20128A498	List: ML20128A495 ML20128A522 ML20128A558
References
NUDOCS 9302020246
Download: ML20128A558 (3)

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SAFETY EVALVATION BY THE OFFIC1_DF NVCLEAR REACTOR REGVLATION RELATED TO AMENDMENT N0. 173 TO FACILITY OPERATING LI. CENSE NO. DPfl-J1

&ND AMENDMENT NO. 172 TO FAClllTY OPERATING LICENSE NO. DPR-37 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION. UNIT NOS. 1 AND 2 DOCKET NOS. 50-280 AND 50-281 1.0 INTRODVCTION Pursuant to 10 CFR 50.90, by letter dated September 4. 1992, the Virginia Electric and Power Company (the licensee) requested a revision to the Technical Specifications (TS) Section 4.17 of Facility Operating License Nos.

DPR-32 and DPR-37 for the Surry Power Station, Units 1 and 2, respectively.

This proposed revision would modify the acceptance criteria for functional testing of the Anchor Darling mechanical snubbers, in addition, other administrative changes are being proposed to provide consistency in terminology and to note that functional testing is in accordance with the approved inservice inspection program.

2.0 BACKGROUND

Both hydraulic and mechanical snubbers are installed at the Surry Power Station (SPS). The TS require periodic testing of the hydraulic and mechanical snubbers to confirm operability by satisfying the appropriate acceptance criteria as currently defined in the TS. During the last several refueling outages, the licensee has replaced the originally installed Pacific Scientific mechanical snubters with Anchor Darling mechanical snubbers. Since the Anchor Darling mechanical snubbers operate in a different manner than the Pacific Scientific mechanical snubbers, the existing TS acceptance criteria for functional testing of the mechanical snubbers are not applicable to the Anchor Darling mechanical snubbers for operability determinations.

3.0 EyALUATION The existing acceptance criteria for functional testing (Technical Specification 4.17.E) require that: 1) the force that initiates free movement of the snubber rod in either tension or compression is less than the maximum drag force, and 2) the drag force shall not have increased by more than 50%

since the last functional test. The originally installed Pacific Scientific mechanical snubber was an acceleration limiting device that utilized a mass inside the snubber to limit acceleration during sudden movements or seismic 9302020246 930122 PDR ADOCK 05000280 P PDR

disturbances. The breakaway drag force (the force that initiates free movement) was measured for the Pacific Scientific mechanical snubbers to demcnstrate free movement. The Anchor Darling DynaDamp snubber is a velocity limiting device that utilizes an oscillatory type escapement mechanism to restrict pipe movement at a constant velocity. The snubber is always engaged and resists movement proportional to velocity. Thus, there is no " free movement." Consequently, the drag force that is required to maintain the snubber movement at a constant velocity is a more meaningful measure of the snubber's ability to move with the piping without imposing undue restraint.

Secondly, due to the difference in the functional mechanisms of their snubbers, a 50% relative increase in drag force is not a meaningful critorion for determining operability of Anchor Darling snubbers. Since the measured drag force can be highly variable from test to test, a 50% relative increase in measured drag force may only be indicative of measurement or test uncertainty. The absolute value of the drag force, as compared to a specified maximum acceptable value, is a much better indicator of snubber performance.

Technical Specification 4.17.C.6 requires that for each snubber which fails to meet the functional test acceptance criteria (less than 50% increase in drag force) of lechnical Specification 4.17.E an additional 10% of that type of snubber be functionally tested. Verbatim compliance with the TS requirements would require additional functional testing of a 10% sample of the Anchor Darling mechanical snubbers based on an inappropriate and non-applicable acceptance criteria.

3.1 Pt apased channes to the TS The following Technical Specification changes are being proposed to Technical Specification 4.17:

o Change the word " type" to " category" in Technical Specification 4.17.A.1 for consistent terminology.

o Change the word " category" to " type" in Technical Specification 4.17,C.7 for consistent terminology.

o Modify the mechanical snubber functional testing acceptance criterion in Technical Specification 4.17.E. to require that "the drag force in both tension and compression is less than the specified maximum drag force."

o Clarify the Basis to identify that functional testing is performed in accordance with the approved Inservice Inspection Program rather than the general reference to the ASME Code, o Modify the wording of Technical Specification 4.17 C.1 to be more definitive, o Capitalize defined words and system names.

4.0

SUMMARY

The staff has reviewed the licensee's proposed revision to TS Section 4.17 and finds it to be acceptable.

5.0 STATE CONSULTATION

in accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendments. The State official had no comment.

6.0 ENVIRONMENTAL CONSIDERATION

These amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there it no significant increase in individual or cumulative occupational radiation exposure. The Commission has previously issued a proposed finding that these amendments involve no significant hazards consideration and there has been no public comment on such finding (57 FR 47142). Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR-Sl.22(c)(9). Pursuant to 10 CFR 51.22(b) no environmental impact statement or-environmental assessment need be prepared in connection with the issuance of these amenaments.

7.0 CONCLUSION

The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the

-public will not be endangered by operation in the proposed manner, (2) such-activities wi'il be conducted in compliance with the Commission's regulations, and (3) the issuance of these amendments will not be inimical to the common defense and security or to the health and safety of the public.

Principal Contributor: B. Buckley Date: January 22, 1993