ML20059H496
| ML20059H496 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 11/02/1993 |
| From: | Simpkin T COMMONWEALTH EDISON CO. |
| To: | Murley T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-070, REF-GTECI-094, REF-GTECI-NI, TASK-070, TASK-094, TASK-70, TASK-94, TASK-OR GL-90-06, GL-90-6, NUDOCS 9311100102 | |
| Download: ML20059H496 (3) | |
Text
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L' November 2,1993 Dr. Thomas E. Murley, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Attn: Document Control Desk
Subject:
Zion Station Units 1 and 2 Supplement to Application for Amendment to Facility Operating Licenses DPR-39 and PR-48 Appendix A, Technical Specifications.
NRC Docket Nos. 50-295 and 50-304
References:
(a)
June 25,1990, Generic Letter 90-06, Resolution of Generic.
Issue 70, " Power Operated Relief Valve and Block Valve Reliability," and Generic issue 94, " Additional Low-Temperature Overpressure Protection for Light-Water Reactors," Pursuant'to 10 CFR 50.54(f).
(b)
December 6,1990 letter from Darrell Taylor to U.S. NRC.
(c)
July 8,1992 letter from S.F. Stimac to T.E. Murley
Dear Dr. Murley:
With Reference (c), Commonwealth Edison Company (CECO) proposed to amend Appendix A, Technical Specifications of Facility Operating Licenses DPR-39 and DPR-48, Zion Station Units 1 and 2, respectively. The proposed amendment would revise Specifications 3/4.3.1.F and 3/4.3.2.G to address the concerns of Generic Letter 90-06, Reference (a), relative to power operated relief valves and low temperature overpressure protection. The proposed changes were consistent with CECO's response to Generic Letter.
90-06 provided in Reference (b).
In the Reference (c) application, CECO requested a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> timeframe to accomplish the depressurization of the Reactor Coolant System. Attached please find a discussion of the evolution which demonstrates the necessity of the requested tirne.
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Dr. T.E. Murley November 2,1993 Commonwealth Edison is notifying the State of Illinois of this additional information by transmitting a copy of this letter and its attachments to the designated State Office.
To the best of my knowledge and belief, the statements contained herein are true and correct. In some respects, these statements are not based on my personal knowledge but upon information received from other Commonwealth Edison and contractor employees received from. Such information has been reviewed in accordance with Company practice, and I believe it to be reliable.
Please direct any questions you may have regarding this matter to this office.
Respectfully, N
i T.W Simpki Nuclear Licensing Administrator Attachment
.j cc:
J.B. Martin, Regional Administrator - Alli J.D. Smith, Senior Resident inspector - Zion C.Y. Shiraki, Project Manager - NRR Office of Nuclear Facility Safety - IDNS I
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ATTACHMENT A JUSTIFICATION FOR 24 HOUR DEPRESSURIZATION TIME In order to demonstrate that the requested 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> timeframe to cooldown and depressurize the plant is necessary, a brief description and minimum approximate timeframes are presented below. The assumed initial conditions are as follows:
RCS average temperature - 250 DegF RCS pressure - 400 psig RCP's in operation - 2 Bubble in pressurizer Pressurizer level - 35%
Residual Heat Removalin operation Cooldown Rate of 50 DegF/ hour.
The evolution for which the 24 timeframe is requested requires that the pressurizer first be filled solid, then the RCS cooled down to 150 DegF. This evolution requires approximately 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br />, including time to perform RCS chemistry sampling. The major reason for this length of time is the slow charging rate (<25 gpm) which is required to ensure that the pressurizer cooldown limits are not violated.
An additional 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> is required for shift turnover, valve lineups, and cooldown to less than 150 DegF. At this time, the Pressurizer Relief Tank must be drained, valve lineups inside containment performed for a nitrogen blanket on the pressurizer, and the pressurizer drained to less than 25%. This evolution requires approximately 9.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.
The major contributor to this evolution is the draining process due to' the 30 gpm letdown rate.
These timeframes collectively total approximately 23 hours2.662037e-4 days <br />0.00639 hours <br />3.80291e-5 weeks <br />8.7515e-6 months <br />, and are accomplished per normal operating procedures in a controlled fashion. No allowance for complications or logistics delays is considered in the above estimate.
As demonstrated above, the requested 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> timeframe is both reasonable and necessary to accomplish the required evolutions in an orderly fashion.
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