ML20004E202
| ML20004E202 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 06/05/1981 |
| From: | Tramm T COMMONWEALTH EDISON CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| 2122N, NUDOCS 8106110340 | |
| Download: ML20004E202 (3) | |
Text
CN) Ons First National Plats Chicago, Ilhnois Commonwealth Edison
[
{ C 'y Addr&ss R: ply to: Post Offica Box 767 y
/ Chicago, Illinois 60690 June 5, 1981 Mr..Marold R. Denton, Director Office of Nuclear Reactor Regulation
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U.S. Nuclear Regulatory Commission f)\\(
D Washington, DC 20555 s
i
Subject:
Zion Station Units 1 and 2 i:
<e 6
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L Additional Information Regarding Proposed Technical Specification d
/A Changes Regarding the Rod' Bow k?)j 8/
g\\s Penalty NRC-Dockets 50-295 and 50-304
(
8' Reference (a):
April 13, 1981, letter from T. R. Tramm X
to H. R. Denton.
Dear Mr. Denton:
In reference (a), Commonwealth Edison Company proposed a revision of Zion's Technical Specifications to remove the rod bow penalty from the equation used to calculate the radial peaking factor limit.
During telephone conversations with members of the NRC Staff it was requested that additional information be supplied.
Attachment A to this letter contains the requested information.
Please direct further questions to this office.
One original and thirty-nine (39) copies of this letter are provided for your use.
Very truly yours, T r (E. V W 1
T. R. Tramm l
Nuclear Licensing Administrator Attachment cc:
Zion Resident Inspector lm 2122N N
8106 110 P
4
---n,
ATTACHMENT A Additional Information Regarding Removal _of Fuel Rod Bow Penalty Request (a):
Provide the magnitude of the margins that were used to offset the reduction in DNBR due to fuel rod bowing.
Has NRC approved these margins for Zion applications?
If not, please provioe the necessary justification.
Response (a):
The generic DNBR thermal margins identified in the original transmittal which are employed to offset the fuel rod bow DNBR penalty are listed as follows:
(a)
Design Pitch Reduction 3.3%
(b)
Thermal Diffusion Coefficient 3.0%
(c)
Design Limit DNBR of 1.24 4.8%
(allowed) versus 1.30 (used in analysis)
(d)
New Densification Spike Model
_7.0%
Total 18.1%
These margins more than offset the bow penalty for the range of burnups of concern (less than 33,000 MWD /MT).
As stated in the original transmittal, no rod bow penalty for fuel with region average burnups greater than 33,000 MWD /MT is required due to the peaking factor burndown effect.
Request (b):
Are the margins used to offset rod bowing DNBR penalties employed solely for this purpose?
If not, please provide justification for using this margins more than once.
Response (b):
These margins are employed solely for the purpose of j
offsetting the rod bow penalty.
Request (c):
The reduction in DNBR due to rod bowing for the loss-of-flow transient and N-1 loop operation is greater than the reduction in DNBR for other conditions.
Is additional available margin used, or is the calculated limiting DNBR sufficiently large to offset this incremental penalty?
Response (c):
The margins are sufficiently large to offset the bow penalty under all currently analyzed conditions, including the loss l
of flow transient.
Since the Zion units are not currently licensed l
for N-1 Loop operation, it has not been addresseo in this submittal.
I t
o.-
. Request (d):
Amend the Basis of the Technical Specifications to iaentity each generic or plant specific margin that has been used to offset the reduction in DNBR due to rod bowing.
Also reference either the source or approval of each generic margin.
Response (d):
The following paragraph is suitable for inclusion in the Bases before the first full paragraph on Page 68:
The rod bow penalty on the FN H limit has been eliminated by taking credit for available generic DNBR thermal margins which include (1) the design pitch reduction, (2) the thermal diffusion coefficient, (3) the design DNBR valve, and (4) the densification power spike factor.
For fuel with a region average burnup of greater tha
.redit is alsotakenforthepeakingfactor(Fg33,000 MWD /MT, AH) burndown effect.
2122N i
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