ML20037D055
| ML20037D055 | |
| Person / Time | |
|---|---|
| Site: | McGuire  |
| Issue date: | 05/19/1981 |
| From: | Thies A DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20037D056 | List: |
| References | |
| NUDOCS 8105210314 | |
| Download: ML20037D055 (3) | |
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DUKE POWER COMPANY Powsm Butt.noro 4aa SouTx Cauncir S'azze, CuAmtoTTz, N. C. asson A. c. TMiss P.o Box ante Semion Vice Pet. set f I
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May 19, 1981 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Rrrulatory Commission g
Washington, D.C.
20555
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4 Attention:
Ms. E. G. Adensam, Chief
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Licensing Branch No. 4
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-Y (gd [d D M C Re: McGuire Nuclear Station, Unit 1 8
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Docket No. 50-369 C
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Dear Mr. Denton:
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N Attached are proposed changes to the McGuire Nuclear Station, Unit echnical Specifications. These changes include the following items:
1.
Revised response times and test current values for selected circuit breakers.
2.
Deletion of isolation valves from categorization as containment isolation valves.
3.
Exemption request for selected hydraulic snubbers from periodic functional' testing requirement.
4.
Alternate method for verifying that certain ECCS pumps at a not operable under shutdown conditions.
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5.
Revised value of interlock for isolation of Residual Heat Removal 4
System from Reactor Coolant System.
Each of these items has been reviewed and it has been determined that there are no adverse safety or environmental impacts associated with the proposed changes.
Very truly yours, lO A. C. Thies p $ g [ ' '(
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Attachment g
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Ms. M. J. Graham Mr. James P. O'Reilly, Director Q
T Resident Inspector U.S. Nuclear Regulatory Commission 4 Oj McGuire Nuclear Station Region II 7\\
8165210314
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4 Mr. Harold R. Denton, Director May 19, 1981 Page Two A. C. THIES, being duly sworn, states that he is Senior Vice President of Duke Power Company; that he is authorized on the part of said Company to sign and file with the Nuclear Regulatory Commission this. revision to the McGuire Nuclear Station Technical Specifications, Appendix A to License No. NPF-9; and that all statements and matters set forth therein are true and correct to the best of his knowled e.
F A
A. C. Thies, Senior Vice President Subscribed and sworn to before me this 19th day of May, 1981.
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My Commission Expires:
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ATTACHMENT 1 Technical Specification 3/4.8.3 - Electrical Equipment Protective Devices l
Proposed Change Revise response times and tast current values for selected containment penetration conductor overcurrent protection devices in Table 3.8-1 as shown on Attachment 1A.
Also revise 4.8.3.1 a.2. as indicated in At-tachment IB to reflect changes in Table 3.8-1.
Justification and Safety Analysis The proposed change involves changing the response times for molded case circuit breakers. The values of response times in the Technical Speci-fication currently reflect the time required for a circuit breaker to open when a test current equal to 200% of the nominal continuous rating of the breaker is injected.
The manufacturer recommends using a test current equal to 300% of the nominal continuous rating for testing.
Using this 300% value requires that the response time acceptance criteria be lowered to account for the increased current.
i In addition to lowering the response time acceptance criteria, it is pro-posed that only the maximum acceptable response time be listed in Table 3.8-1 rather than a range of response times.
Incorporation of these pro-posed changes will enhance the testability of these circuit breakers and bring the testing into conformance with the manufacturer's recommendations.
l Testing the response time of the molded case circuit breakers provides some level of assurance that these breakers would operate as required in the event of an overcurrent condition and thereby protect the containment electrical penetration associated with the breaker.
The response time of a breaker of this type will vary depending on the magnitude of the over-current to which it is subjected; a very large overcurrent would result in an " instantaneous" breaker trip whereas a slight overcurrent condition would require an extended period of time for breaker trip.
For testing purposes it is impractical to use very large test currents so nominal values are used to check the trip feature.
Increasing the test current l
value from 200% of breaker continuous rating to 300% and decreasing the response time accordingly simply shif ts the test point on the response time vs. overcurrent curve.
From the standpoint of containment electrical penetration protection, the minimum response time for breaker trip is unnecessary. The important parameter is the maximum allowable response time, i.e.,
penetration pro-tection is assured as long as the maximum response tims
'.s not exceeded.
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