ML20133G955
| ML20133G955 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 10/11/1985 |
| From: | Shell R TENNESSEE VALLEY AUTHORITY |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8510160200 | |
| Download: ML20133G955 (3) | |
Text
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TENNESSEE VALLEY AUTHORITY r
CH ATTANOOGA. TENNESSEE 37401 400 Chestnut Street Tower II October 11, 1985 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Dear Mr. Denton:
In the Matter of the
)
Docket Nos.
50-327 Tennessee Valley Authority
)
50-328 This is in reference to our efforts at Sequoyah Nuclear Plant (SQN) to meet the requirements of 10 CFR 50.62, paragraphs (C)(1) through (C)(5),
regarding the reduction of risk from Anticipated Transients Without Scram (ATWS) events for light-water-cooled nuclear power plants.
Pararraphs (C)(3), (C)(4), and (C)(5) apply only to boiling water reactors and paragraph (C)(2) does not apply to Westinghouse reactors.
Therefore, only the requirements of paragraph (C)(1) apply to our efforts at SQN.
We will install ATWS mitigating system actuation circuitry (AMSAC) at SQN based on a generic functional design developed by the Westinghouse owners Group (WOG). The AMSAC system to be implemented is logic to actuate a turbine trip and auxiliary feedwater flow upon sensing that steam generator 4
water levels are below tho low-low setpoint. This logic senses conditions indicative of an ATWS event when the loss of a heat sink has occurred, but actuation will not occur until af ter the reactor protection signals should have been generated. This logic will be blocked below 70-percent rated thermal power to minimize spurious activations.
This design reflects the first of three generic functional designs developed by WOG. Westinghouse Topical Report WCAP-10858 describing the generic options was submitted to NRC for review and approval on July 25, 1985 by letter from L. D. Butterfield to Dr. C. O. Thomas. We had received preliminary indications, through WOG, that NRC intended to issue a safety evaluation report (SER) on the generic designs by the end of September 1985.
It is now our understanding that the SER will not be issued until at least mid-November of this year.
0510160200 85 h
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/7 0
l An Equal Opportunity Employer
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1 I
l Mr. Harold R. Denton, Director October 11, 1985 a
l Although NRC has not yet issued the SER concerning the options developed by 1
WOG, TVA decided on a specific option for SQN in order to meet the deadline in paragraph (d) of the ATWS rule. haterials are in the process of being procured and installation schedules have been developed. The AMSAC equipment will be installed and operable at SQN for unit 1 by the end of the cycle 4 refueling outage and for unit 2 by the end of the cycle 3 refueling outage. These outages correspond to the second refueling outage after July 26, 1984 for each unit and meet the scheduling requirements of paragraph (d) of the ATWS rule.
Very truly yours, TENNESSEE VALLEY AUTHORITY
)
R. H. Shell Nuclear Engineer Sworn nd subscr efore me i
this day of
_ 1985 d
14 i
Notary Public g
My Commission Expires A '
cc:
U.S. Nuclear Regulatory Commission Region II Attn:
Dr. J. Nelson Grace, Regional Administrator i
101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 1
Mr. Carl Stahle Sequoyah project Manasse i
U.S. Nuclear Regulatory Commission l
d 7920 Norfolk Avenue Bethesda, Maryland 20814 8
1
.~
v Director of Nuclear Reactor Regulation October 11, 1985 DEN:JDZ:KEH cc: NUC PR RINS, 1520 CST 2-C H. L. Abercrombie, NUC PR, Sequoyah John Hutton, 1760 CST 2-C K. M. Jenison, Sequoyah - NRC R. J. Nullin, 1350 CUBB-C (2)
J. A. Raulston, W10 C126 C-K H. S. Sanger, Jr., E11 B33 C-K F. A. Szczepanski, 220 401B-C K. W. Whitt, E3 A8 C-K bc:
R. E. Alsup, 400 CST 2-C C. Reeves NUC PR, Sequoyah J. H. Sullivan, NUC PR, Sequoyah COORDINATED:
H. L. Abercrombie/SQN and J. E. Wills /LPI.
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