ML20215K193
| ML20215K193 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 10/21/1986 |
| From: | Capstick R VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Rooney V Office of Nuclear Reactor Regulation |
| References | |
| FVY-86-98, NUDOCS 8610280022 | |
| Download: ML20215K193 (2) | |
Text
,
VERMONT YANKEE NUCLEAR POWER CORPORATION RD 5, Box 169, Ferry Road, Brattleboro, VT 05301 y
ENGINEERING OFFICE 1671 WORCESTER ROAD FR AMINGHAM. MASSACHUSETTS 01701 T EL E PHONE 617-872-8100 October 21, 1986 FVY 86-98 United States Nuclear Regulatory Commission Washington, DC 20555 i
Attention:
Office of Nuclear Reactor Regulation Mr. Vernon L. Rooney BWR Project Diractorate #2 Division of BWR Licensing
References:
(a) License No. DPR-28 (Docket No. 50-271)
(b) Letter, VYNPC to USURC, FVY 86-34, dated April 25, 1986,
" Proposed Technical Specification Change for Spent and New Fuel Storage" (c) Letter, USNRC to VYNPC,~NVY 86-147, dated July 24, 1986 (d) Letter, VYNPC to USNRC, FVY 86-73, dated August 15, 1985 (e) Letter, VYNPC to USNRC, FVY 86-88, dated September 26, 1986
Subject:
Response to Request for Additional Information - Spent Fuel Pool Expansion
Dear Sir:
In response to your request of September 25, 1986, Vermont Yankee herein provides additional information in support of our proposed Technical Specification change for spent fuel pool storage [ Reference (b)).
In the referenced submittal of the Vermont Yankee high density spent fuel rack design, a K~ infinity acceptance criteria of 1.35 in the cold reactor lattice was specified. This was modelled in the criticality analysis as an 8 x 8 array of fuel rods with a uniform fuel enrichment of 3.25 w/o U235. This modelling clearly bounded the present and expected maximum assembly reactivity and produced a rack K-effective of.9267 with all mechanical and methodology uncertainties applied.
l With regard to the application of the maximum bundle K-infinity l
acceptance criteria, we have quantified the K-infinity acceptance criteria to.
]
account for the following:
1.
Nonuniform enrichment variations within the assembly lattice which
)
would impact the rack K-effective relative to the uniform enrichment
- model, l
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a United Stat'es Nuclear Regulatory Commission October 21, 1986 Attention:
Mr. Vernon L. Rooney Page 2 2.
Uncertainty in the ability to calculate maximum assembly cold K-infinity, and 3.
Uncertainty in average assembly enrichment.
Accordingly, the K-infinity of 1.35 will ba reduced to 1.31 based on the conservative application of the following bundle uncertainties:
1.
A.02 delta K bounds the reactivity associated with assembly enrichment variations.
I 2.
The ability to calculate cold K-infinity is within.01 delta K with greater than 95/95 percent confidence.
3.
The uncertainty in average assembly enrichment is 1 013 w/o U235 and affects the delta K by less than.01.
We trust that the above is responsive to your request; however, should you have any questions or require further information regarding this matter, please contact this office.
I Very truly yours,
)
VERMONT YANKEE NUCLEAR POWER CORPORATION
[I s
R. W. Capstick Licensing Engineer RWC/dml
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