ML20136J405

Responds to Request for Addl Info Re 850913 Application for Amends to Licenses DPR-57 & NPF-5,allowing 60 Closure Time Limit for Scram Discharge Vol Vent & Drain Valves.Figure 6.2.2 from GE NEDO-24342 Re Scram Sys Pipe Breaks Encl

ML20136J405
Person / Time
Site:	Hatch
Issue date:	11/18/1985
From:	Gucwa L GEORGIA POWER CO.
To:	Stolz J Office of Nuclear Reactor Regulation
References
SL-85-11, TAC-53327, TAC-53328, NUDOCS 8511250357
Download: ML20136J405 (3)

Text

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Georgia Power Company 333 Piedmont Avenue -

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' Atlanta, Georg a 30308 T.

Telephone 404 5266526 Maibog Aodress:

Post Office Box 4545 Atlanta, Georgia 30302 Georgia Power

' L T. Gucwa Ine southern electnc system Manager Nuclear Engineering and Chief Nuclear Engineer SL-85-11 0059C November 18, 1985 Director of Nuclear Reactor Regulation Attention:' Mr. John F. Stolz, Chief 0perating Reactors Branch No. 4 Division of Licensing U. S. Nuclear Regulatory Commission Washington, O.

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20555 NRC DOCKETS 50-321, 50-366 OPERATING LICENSES DPR-57, NPF-5 EDWIN I. HATCH NUCLEAR PLANT UNITS 1, 2 SCRAM DISCHARGE VOLUME VENT AND DRAIN VALVE CLOSURE' TIME TECHNICAL-SPECIFICATIONS Gentlemen:

In response to requests from the NRC staff, the following additional information is provided regarding our Technical Specification change proposal of September 13, 1985.

That submittal proposed a 60 second closure time limit for the scram discharge volume (SDV) vent and drain valves, based on a recent General Electric Company analysis.

An earlier analysis, provided as an attachment to our letter on the same subject dated December 22, 1983, specified a gravity drain rate for the SDV of

-12 gallons per minute (gpm).

This figure should have been specified as the time to drain, in minutes, rather than a flowrate.

The correct flowrates are approxTmately 30 gpm for Unit 1 and approximately 50 gpm for Unit 2, which correlate to GE's calculations.

To quantitatively establish actual post scram SDV inflow, control rod y

drive stall flow '(CRD seal leakage flow) test data have been obtained for Hatch Units 1 and 2 during two operating cycles.

These numbers are as follows (ingallonsperminuteperaveragedrive):

Unit 1:

Current Cycle - 2.79 gpm Previous Cycle - 2.58 gpm Unit 2:

Current Cycle - 2.27 gpm Previous Cycle - 2.37 gpm B511250357 851118 i

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Georgia Power d Director of Nuclear Reactor Regulation Attentior-Mr. John F. Stolz, Chief Operating Reactors Branch No. 4 November 18, 1985 Page Two General Electric Company Topical Report NE00-24342, entitled "GE Evaluation in Response to NRC Request Regarding BWR Scram System Pipe Breaks",

dated April 1981, provides a correlation (Figure 6.2.2 - attached) between measured stall flow (measured at power with control rod fully withdrawn) and post scram leakage flow into the SDV.

This correlation, in conjunction with the Hatch stall flow test data, can be used to perform a bounding calculation for SDV overfilling.

T6.e Unit 1 SDV is the limiting (smaller) volume.

Per as-built calculations, the Unit 1 SDV has a volume of 549 gallons.

Assuming the worst-case measured average stall flow of 2.79 gpm per drive, and using the correlation provided in NE00-24342, it is possible to perform a calculation for Unit 1 (which bounds Unit 2) which demonstrates that the SDV will not overfill with a 60 second vent and drain valve closure time limit, assuming zero flow out the drain lines.

This conservative calculation, well as operating experience, substantiates the conclusion that the 60 second as closure time limit is acceptable.

Please contact this office if you desire further information.

Very truly yours, cf 7" & c_,

L. T. Gucwa REB /lc Attactaent Dr. J. N. Grace, (NRC-Region II) c:

Mr. J. T. Beckham, Jr.

Mr. H. C. Ni x, Jr.

Senior Resident Inspector - Hatch GO-NORMS t

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9 WITHDR AW STALL FLOW AT 250 paid (gami Figure 6.2.2.

Post Scram Leakage vs. Withdrawn Stall Flow 6-12

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