ML17325A040
| ML17325A040 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 04/09/1987 |
| From: | Alexich M INDIANA MICHIGAN POWER CO. (FORMERLY INDIANA & MICHIG |
| To: | Harold Denton NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| AEP:NRC:0936F, AEP:NRC:936F, NUDOCS 8704140274 | |
| Download: ML17325A040 (6) | |
Text
ACCESSION NBR:
FAC IL:50-315 50-318 AUTH. NAME ALEXICH>N. P.
REC IP. NAl'fE REQULATORY NFORNATION DISTRIBUTION SY l'1 (R IDS) 8704140274 DOC. DATE: 87/04/09 NOTARIZED:
NO DOCKET Donald C.
Cook Nuclear Pouer Planti Unit 1.
Indiana 5
05000315 Donald C.
Cook Nuclear Power Plant>
Unit 2>
Ind iana 5
05000316 AUTHOR AFFILIATION Ind iana
!c Nichigan Elec tric Co.
RECIPIENT AFFILIATION Document Control Branch (Document Control Desk )
SUBJECT:
Responds to NRC request for info re reactivitg effects of steam generator crevice flushing. Reactivitg impact of RCS temp increase from 200 F to 30 F examined. Ader}uacg of shutdown margin evaluated bg comparing reactivitg insertion.
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INDIANA8 A1ICHIGAN ELECTRIC CON PANY P.O. BOX 16631 COLUMBUS, OHIO 43216 April 9, 1987 AEP:NRC:0936F Donald C.
Cook Nuclear Plant Unit Nos.
1 and 2
Docket Nos.
50-315 and 50-316 License Nos.
DPR-58 and DPR-74 REACTIVITY EFFECTS OF STEAM GENERATOR CREVICE FLUSHING U.S. Nuclear Regulatory Commission Attn:
Document Control Desk Washington, D.C.
20555 Attn:
H. R. Denton
Dear Mr. Denton:
It tt
=In.response to a request from the'NRG staff, we,have examined the, reactivity impact of" a Reactor Coolant System (RCS) temperature increase 0
0 from 200 F to 330 F that-is required for steam generator crevice flushing.
During crevice flushing, all four steam generators are conditioned with hydrazine as needed and boric acid, pressurized with nitrogen, and heated 0
to approximately 300 F via the reactor coolant.
The steam generators are then repeatedly depressurized,
- drained, and refilled to flushing level.
During the heating and cooldown that will occur intermittently in this
- process, there will be changes in reactivity, and I&HECo was requested to evaluate the adequacy of the shutdown margin because Cook Plant cores have a positive isothermal temperature coefficient at the beginning of life.
This was performed by comparing the reactivity insertion due to positive temperature coeeficient with the shutdown margin available via the RCS boron.
During crevice flushing, the boron concentration in the RCS will be maintained at the level required for 68 F.
This shutdown boron concentration assumes that the most reactive RCCA is stuck out of the core, although all rods are known to be inserted.
The shutdown boron also provides a 100 ppm ~000 pcm) allowance for boron depletion and a 100 ppm
(~1000 pcm) allowance for conservatism.
The depletion of the overall plant inventory of boric acid is less than 1%.
For Unit 2, Cycle 6, the total reactivity margin due to the above. is approxmately 3191 pcm.
The reactivity insertion due to positive isothermal temperature coefficient and RCS temperature increase from 200 F to 330 F at beginning of life is approximately 410 pcm for Unit 2, Cycle 6.
Since the reactivity insertion is substantially less than the margin available, adequate shutdown margin is maintained.
We believe that this large margin supports the availability of the shutdown margin for both units and for all cycles.
L 8704140274 870409
- PDR, ADOCK 05000315 P
0 0
'r v~
AEP:NRC:0936F At end of life, the isothermal temperature coefficient is negative and therefore RCS temperature increase does not cause reactivity insertion.
During the process of steam generator crevice flushing, the RCS temperature may drop slightly.
Since shutdown boron concentration for 68 F is maintained, adequate shutdown margin is maintained for cooldown from 330 F.
This document has been prepared following Corporate procedures which incorporate a reasonable set of controls to insure its accuracy and completeness prior to signature by the undersigned.
Very truly yours, M.
Ale ch Vice Pres dent cm cc:
John E. Dolan W.
G. Smith, Jr.
- Bridgman R.
C. Callen G. Bruchmann G. Charnoff NRC Resident Inspector
-,Bridgman A. B. Davis
- Region III
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