ML19263C036
| ML19263C036 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 01/29/1979 |
| From: | Reed C COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 7902020174 | |
| Download: ML19263C036 (3) | |
Text
jh Commonwealth Edison my one rust teatenal riara. CNcago, til.nois N./f/ Adaress Heply to: Post Othcc Dox 767 g/ Chicago, Ilhnois 00690 January 29, 1979 Mr. Harold R. Denton, Director Office of Nucle.- Reactor Regulati a
U.S. Nuclear Regulatory Commission Washington, DC 20555
Subject:
Zion Station Units 1 and 2 Revised ECCS Evaluation NRC Docket Nos. 50-295 and 50-304 Reference (a):
January 10, 1979 letter trom Cordell Reed to Harold R.
Denton titled " Zion Station Units 1 and 2 Revised ECCS Evaluation."
(b):
April 21, 1978 letter from A.
Schwencer to Cordell Reed containing Order for Modification of License.
(c):
January 24, 1979 letter from Cordell Reed to Harold R.
Denton titled " Zion Unit 1 Base Load Operation Under
~
Revised ECCS Evaluation."
(d) :
January 25, 1979 letter from cordell Reed to Harold R.
Denton titled " Zion Station Unit 1 Additional Information for Base Load Operation Under Revised ECCS Evaluation."
Dear Mr. Denton:
Per Reference (a), Commonwealth Edison Company informed the NRC StafE of the results of an ECCS reanalysis performed in accordance with the Westinghouse ECCS Evaluation Model apprcved by the NRC Staff in August 1978.
The results of this analysis in-dicated that the Zion Units 1 and 2 F peaking factor limit had g
decreased to a value of 1.86 for an accumulator level range of 769 3
to 818 ft This value was significantly lower than the F limit of 2.04 for an accumulator range of 851 to 866 ft3 g
as specified by Reference (b), April 21, 1978 Order for Modification of License.
Therefore, as outlined in Reference (a), Zion Station took the following action:
/
790202oM4
Commonwealth Edison NRC Docket Nos. 50-295/304 Mr. Harold R.
Denton: January 29, 1979 1.
For Zion Unit 1, the Fg limit of 1.86 was programmed into the installed APDMS surveillance equipment with the result that operation with this linit required utiliration of APDMS type surveillance for power levc ls above 88% of rated power with a resultanc power doration E 5-7%; and 2.
For Zion Unit 2, no immediate action was neccesary as this unit was in a coastdown mode of operation and well below the revised F limit.
g With regard to the difference in accumulator levels, Westinghouse and Commonwealth Edison have determined that the difference is more than compensated for by the additional margin in as-built fuel pellet temperatures which were not included in the revised analysis and by the margin that exists between the revised analysis temperature of 2174 F and the 2200 F limit.
- Thus, Commonwealth Edison has determined that an immediate change in accumulator levels is not necessary at this time and that any change would be more appropriately handled after final approval of the reevaluation called for in Reference (b).
This letter is to inform the NRC Staff that the re-evaluation called for in Reference (b), Order for Modification of License, has been completed and also to transmit advance copies of the reevaluation for Staff review.
The results of this reevaluation reflect the revised F limit of 1.86 described herein.
g Currently, commonwealth Edison is in the process of completing a full response to the Order.
A review of the reevaluation is being performed to prepare the appropriate license mnendment and its associated technical specification changes.
The completed package will be submitted on February 2, 1979.
With this letter, common.iealth Edison requests the NRC Staff to commence its review immediately.
Pending NRC Staff review and approval of Commonwealth Edison's final submittal, commonwealth Edison will continue to operate Zion Station within an Fg peaking factor limit of 1.86 as described in Reference (a).
In addition, commonwealth Edison will observe any other restrictions that may arise as a result of Edison's review.
O
Commonwealth Edison lac Docket Nos. 50-295/304 l-y Mr. Harold R.
Denton: January 29, 1979 p
F Since Zion Unit 1 is restricted to about 95% of rated power due to the utilization of APDMS, Commonwealth Edison also
(
requests that the NRC Staff authorize, as soon as possible, Lj L
Commonwealth Edison's request contained in References (c) and (d) for base load operation without APDMS.
As a supplement to Reference (d), an additional full core flux map was performed on f
Zion Unit 1 on January 25, 1979 with the following results:
h r
Core Burnup Map 4
% Power Fn*
(MWD /MTU) 1-4-12 94.4 1.68 2626
.t
- Includes 3% engineering and 5% measurement uncertaintics.
i e
E One (1) signed original and four (4) copies of this letter are provided for your use.
Five (5) copics of the ECCS t
reevaluation per Reference (b) have been provided under separate I
k cover.
t L
Very truly yours, y
On Cordell Reed Assistant Vice-President b
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