ML20154N459
| ML20154N459 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 03/10/1986 |
| From: | Capstick R VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Rooney V Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20154N464 | List: |
| References | |
| FVY-86-19, GL-83-08, GL-83-8, GL-83-89, NUDOCS 8603170328 | |
| Download: ML20154N459 (2) | |
Text
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kERMONT YANKEE NUCLEAR POWER CORPORATION FVY 86-19 RD 5, Box 169, Ferry Road, Brattleboro, VT 05301
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. y ENGINEERING OFFICE 1671 WonCESTER ROAD FRAWGHAM. MASSACHUSETTS 01701 March 10, 1986 T EL E PHONE 617-872-4100 United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Office of Nuclear Reactor Regulation Mr. Vernon L
_ooney, Project Manager BWR Project.,irectorate No. 2 Division of BWR Licensing
References:
(a) License L3. DPR-28 (Docket No. 50-271)
(b) Letter, USNRC to VYNPC, NYY 83-23, Ceneric Letter 83-08, dated February 2, 1983 (c) Letter, VYNPC to UONRC, FVY 83-36, dated May 11, 1983 (d) Letter, USNRC to VYNPC, NVY 86-10, dated January 17, 1986
Subject:
Modifications of Vacuum Breakers on Mark 1 Containments (Generic Let.t.ec 83-08)
Dear Sir:
By letter dated January 17, 1983 (Reference (d)), you requested additional information related to the Vermont Yankee torus-to-drywell vacuum breaker modification in order to complete your review initiated under Ceneric Letter 83-08 (Reference (b)).
In response to your request, attached please find the information requested in the enclosure to your letter.
We trust this information is satisfactory; however, should you have any quertions or require additional information, please contact this office.
Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION J
R. W. Capstick Licensing Engineer RWC/no Attachment Me 4cb y M (J u t e A M S r
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Response to NRC Request for Additional Information Related to the Modification of Vacuum Breakers on Mark I containment at Vermont Yankee Nuclear Power Station.
Question 1:
Is the chugging source rate used in the Vermont Yankee evaluation the same as the one developed in CDI Report
(#84-3)? If not the same, provide the chugging source rate with the supporting justification.
Answer:
Yes. The methodology followed in CDI Report Number 84-3 (Reference 1) is identical to the methodology used in the Vermont Yankee evaluation (Reference 2 - attached) and detailed in response to NRC Question Number 5 in Reference 3.
Question 2:
Did the Vermont Yankee calculation apply the 1.07 load factor to account for the uncertainty in calculating the underpressure (Section IV of the staff's generic evaluation).
Answer:
A load factor, used to assure conservative prediction of the underpressure and detailed in response to NRC Question 2 in Reference 3, was. applied to the Vermont Yankee evaluation (Reference 2).
In fact, the load factor used in the plant unique evaluation was 1.06 and yields a conservative prediction of the underpressure.
Question 3:
Have the Vermont Yankee calculations used the drywell model Which results in the most conservative prediction (Section V of
-the generie avaluatinn)?
Answer:
Yes.
Drywell modeling was examined in response to NRC Question 6 in Reference 3.
For the Vermont Yankee evaluation (Reference 2), the capacitance model results in a more conservative forcing function, and was therefore used.
REFREENCES 1.
"Kark I Wetwell to Drywell Vacuum Breaker Load Methodology, Revision 0,"
Continuum Dynamics, Inc., Report Number 84-3, February 1984.
2.
" Nark I Wetwell to Drywell Differential Pressure Load and Vacuum Breaker Response for the Vermont Yankee Generation Station, Revision 0,"
Continuum Dynamics, Inc., Technical Note Number 84-24, January 1985 3.
" Response to NRC Request for Additional Information on Mark I Containment Program Wetwell to Drywell Vacuum Breaker Load Methodology, Revision 0,"
Continuum Dynamics, Inc. Technical Note Number 84-11, October 1984
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