ML19317D852
| ML19317D852 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/06/1975 |
| From: | Thies A DUKE POWER CO. |
| To: | Moseley N NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| NUDOCS 7912100577 | |
| Download: ML19317D852 (3) | |
Text
coart NRC STRIBUTION FOR PART SO DOCKL MATERIAL (TEMPORARY FORM) 5178 CONTROL NO:
FILE: INCIDELT REPORT TILE FROM: Duke Power Co.
DATE OF DOC DATE REC'D LTR TWX RPT OTHER b$# r5IN 5-6-75 5-10-75 XX TO:
ORIG CC OTHER SENT AEC PDR XX Mr. Norman C. Moseley 1
SENT LOCAL PDR XX CLASS UNCLASS PROPINFO INPUT NO CYS REC'D DOCKET NO:
XXX 1
50-269 DESCRIPTION: Ltr adv of Duke Power Co's ENCLOSURES:
evaluation & decisions regarding the Ocone n 1 ejected rod worth situation after the control rod interchange....
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SCHWENCER (L) ZIEMANN (L)
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W/ Copics W/ Copies W/ Copics W/ Copies CLARK (L)
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MCDONALD MOORE (L)
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CHAPMAN DEYOUNG (L)
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IPPOLITO KNIGHTON M. SLATER (E)
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Iby 6,1975 A,
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Mr. Norman C. Moseley, Director
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U. S. Nuclear Rcgulatory Commission I'
Suite 818 4
230 Peachtree Street, Nortnwest 8[
Atlanta, Georgia 30303
Dear Mr. Moseley:
The purpose of this letter is to advise you of Duke Power Company's evaluation and decisions regarding the Oconce 1 ejected rod worth situation after the control rod interchange.
Unusual Event Report UE-269/75-1, submitted to you on February 14, 1975, concerned the failure to calculate the hot zero power ejected rod worth after control rod interchange during Cycle 1 operation of Oconee Unit 1.
In that report it was stated that the ejected rod worth would be measured at the beginning of Cycle 2 and at the time of the rod inter-change.
It was also stated that if it were not expedient to run the test et the time of the control rod interchange, limits would be placed on the Control Rod Group 5 position during criticality because of uncertainty concerning the ejected rod worth value after the rod interchange at that time.
Since the submittal of UE-269/75-1, several significant developments, which aid in establishing the hot zero power ejected rod worth af ter the control rod _nterchange, have occurred:
1.
The hot zero power ejected rod worths for the beginning of Cycle 2 conditions were measured on Ibrch 10 and 11,1975, and the results were in excellent agreement with L6W's fine-mesh PDQ calculations.
(These results were reported in my letter to you of April 14, 1975.)
2.
The maximum ejected rod worth for Oconce 1, Cycle 2, af ter the rod interchange is calculated to be 0.80% Ak/k.
3.
A comparison of the measured hot zero power ejected rod worths with their calculated values for all operating B&W reactors (as of Jpril 1975) shows that the deviation between the measured hot zero power ejected rod worths and their calculated values has a mean value of 5178
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Mr.1;orman C. Moseley Page 2 May 6, 1975
-8.5 percent, indicating that the calculated values tend to be con-se rvative.
This includes the hot zero power ejected rod worth measurement performed at 125 EFFD in Oconee 2, in which the measured value is 0.57% Ak/k and the calculated value is 0.75% Ak/k.
The general conservatism in B&W's calculation of the ejected rod worths, the close agreement of the beginning of Cycle 2 ejected rod worth measure-ment with the calculated values, and the substantial margin (20 percent) of the calculated hot zero power ejected rod worth after the rod inter-change to the 1.0% Ak/k limit are considered as reasonable assurances i
that the hot zero power ejected rod worth will not exceed the 1.0% Ak/k limit after the rod interchange.
We have, therefore, decided that no restrictions on the control rod group positions will be necessary to meet the hot zero power ejected rod worth criterion for Oconce Unit 1 after the rod interchange.
j Very truly yours, i
A. C. Thies ACT:vr cc:
Mr.'Angelo Giambusso 9
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