ML20053D243
| ML20053D243 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 05/28/1982 |
| From: | Leasburg R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Clark R, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| REF-SSINS-6820 247, IEB-80-04, IEB-80-4, NUDOCS 8206040224 | |
| Download: ML20053D243 (2) | |
Text
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6 VII!GINIA ELECTRIC AND POWER COMPANY RICIIMOND, VIHOINIA 202 61 R. II. Ln Amnu no vic. r...io==r May 28, 1982 NecLeam OrmeArion.
Mr. Harold R. Denton, Director Serial No. 247 Office of Nuclear Reactor Regulation N0/DWL:acm Attention:
Mr. Robert A. Clark, Chief Docket Nos. 50-338 Operating Reactors Branch No. 3 50-339 Division of Licensing License Nos. NPF-4 U. S. Nuclear Regulatory Commission NPF-7 Washington, D. C. 20555 Gentlemen:
NORTH ANNA POWER STAT 10N RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RE: I&E BULLETIN 80-04 In your letter dated April 15, 1982, it was request <
that Vepco provide an evaluation of the ability of the three Auxiliary 1 edwater (AFW) pumps to remain operable for 30 minutes at a runout flow condition.
This information is to be used by an NRC consultant (Franklin Research Center) in the evaluation of the North Anna response to I&E Bulletin 80-04.
Vepco's response to this request is attached.
If additional information is required, contact us at your convenience.
Very truly yours, MMM
(
R. H. Leasburg cc:
Mr. James P. O'Reilly Regional Administrator Region II Atlanta, Ga. 30303
\\
O#3 pll 8206040224 82052e PDR ADOCK 0500033e G
4 Attachment to Ltr. No. 247 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION REGARDING I&E BULLETIN 80-04 I
Request:
Please provide an evaluation of the ability of the motor-driven and turbine-driven AW pumps to remain operable for 30 minutes at runout flow.
Response
With the one to one lineup of AW pumps to S/G's at North Anna, pump runout need only be considered for an AW pump aligned to a faulted S/G.
Back pressure in the intact S/G's would preclude AW pump runout from occurring.
Both motor-driven AW pumps (340 gpm each) have pressure control valves (PCV's) !n the discharge piping of the pumps to regulate back pressure which prevents pump runout.
In the event of a failure of the PCV on a motor-driven AW pump aligned to a faulted S/G, then runout flow could occur for that pump.
However, this condition is not limiting from a containment pressure response concern (IEB 80-04) since the runout flow of the motor driven AW pumps is less than the nominal flow of the turbine-driven AW pump.
Additionally, if runout flow did occur and cause a pump failure within 30 minutes, the accident analysis assumptions for the MSLB transient would not be violated since AW flow to the faulted S/G is terminated at 30 minutes -in the analysis.
Termination prior to 30 minutes would - improve the containment pressure ' response and reduce the RCS cooldown.
The remaining operable pumps aligned to the intact S/G's are adequate for the longer term removal of core heat.
The limiting MSLB case would be for a faulted.S/G aligned to the turbine-driven AW pump (680 gpm).
Runout flow is prevented on the turbine-driven AW pump by a flow restricting orifice in the discharge piping of this pump.
Therefore, operability at a runout flow condition need not be considered since the runout condition is precluded by design.