ML20133K325
| ML20133K325 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 07/22/1985 |
| From: | Gucwa L GEORGIA POWER CO. |
| To: | Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| References | |
| 0739Y, 739Y, NED-85-524, TAC-57643, NUDOCS 8508120196 | |
| Download: ML20133K325 (3) | |
Text
f-s Georgia Pever Conuny 333 Piedmont Avenuc Atlanta Georgia 30308 Tekphor'e 404 5266526 MaSng Addrest i
Post Otrce Box 4N5 Atlanta, Georg:a 30302 Georgia Power 85 JUL26 PIO' 28 L T. Gucwa
,.,,,,,,,,m,_.m.,
Manager Fluclear Enginer.ng and Ch;ef fluclear Engneer NED-85-524 0739y July 22, 1985 U. S. Nuclear Regulatory Commission
REFERENCE:
Office of Iospection and Enforcement RII: RDW Region II - Suite 2900 50-321/50-366 101 Marietta Street, NW Inspection Report Atlanta, Georgia 30323 85-16
)WION: Dr. J. Nelson Grace G-1 4EN:
Georgia Power Company submits the following response to FRC Inspection Report 50-321,366/85-16, dated June 21, 1985, concerning the inspection period of April 28 to May 24, 1985 for Plant Hatch thits 1 and _2.
One apparent violation was identified.
VIOLATION Technical Specification 4.8.2.6.1.a.2 reouires that the functional test for molded case circuit breakers (MCBs) shall consist of injecting a current input at the specified setpoint to the circuit breaker and verifying that the circuit breaker functions as designed.
Contrary to the above, MCBs were being tested per Hatch procedure HNP-2-3850 which reouires the injection of a current at a magnitude greater than that specified as the trip set point in the Technical Specifications.
This testing method is in accordance with National Electrical Manufacturers Association Standards and is technically sound, but is not in compliance with Technical Specifications.
This is a severity level IV violation (Supplement I).
RESPONSE
Admission or denial of alleoed violation:
While the Inspection Report states that, during the exit review "the licensee acknowledged the findings and took no exception,",revi,ew of the events has resulted in our conclusion that a Severity Level IV Violation did not occur.
8508120196 850722 DR ADOCK 05000321 PDR 3 q
y Georgia Power d U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement July 22, 1985 Page 2 RESPONSE (Continued)
A divergence from the exact, literal wording of the portion of the subject Technical Specification which reouires " current input at the specified setpoint" occurred.
However, this description of the test method contains an inconsistency in that such a method would not adeouately verify proper circuit breaker function.
Since our method of testing does meet the intent of the Specification in a technically sound manner, as referenced in the Notice of Violation, it is our position that a Severity Level IV Violation did not occur.
At most, the events demonstrate a failure of the Technical Specifications to address the subject surveillance in a technically sound manner.
Reason for Events Resulting in Alleged Violation:
The circumstances relating to the alleged violation result from the wording of Hatch Unit 2 Technical Specification 4.8.2.6.1.a.2.
This Specification, for demonstrating operability of molded case circuit breakers (MCBs),
recuires that "The functional test shall consist of injecting a current input at the specified setpoint to the circuit breaker and verifying that the circuit breaker functions as designed."
Due to the physical nature of MCBs, it is difficult to verify that the MCB functions "as designed" without injecting a current greater than the "specified setpoint."
National Electrical Manufacturers Association (NEMA)
Standard AB-2, which is the testing method implemented by procedure HNP-2-3850, specifies a test current of 141% of the trip setpoint for testing magnetic only MCBs.
The MCB, due to its design, is not a highly accurate component and has poor repeatability unless tested under controlled conditions.
NEMA AB-2 states that the tolerance for testing under field conditions is +40%, -25%.
Testing an MCB at a test current eoual to the trip setpoint is impractical and can result in overheating and breaker failure.
Testing in accordance with the NEMA Standard gives a better indication of the reaction of the MCB throughout its entire overcurrent trip range.
Later versions of BWR Standard Technical Specifications (STS),
in recognition of this fact, contain an explicit allowance for injecting a test current greater than the trip setpoint.
Earlier versions of BWR Technical Specifications do not contain a table of breakers which protect primary containment penetrations against overcurrent.
To our knowledge, the Hatch Unit 2 Technical Specifications are the only BWR STS containing words which appear to reouire breaker testing a_t the trip t
setpoint.
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Georgia Power d U. S. Nuclear Regulatory Commission Office of Inspection and Enforcement July 22, 1985 Page 3 RESPONSE (Continued)
Our decision to implement the NEMA testing standard in HNP-2-3850 was based on our belief that this standard implemented the Technical Specification, (i. e. demonstrated correct function of the MCBs), in the most technically correct manner.
The NRC also agrees that our present method of breaker testing is technically sound (reference later versions of STS and this Notice of Violation.)
In addition, as described in our letters to NRC dated August 27, 1984 and May 9, 1985, there is no safety significance to the trip setpoints listed in the subject Technical Specification.
The safety function of these breakers is to protect the containment penetrations and provide for primary containment integrity.
Damage to these penetrations would recuire overcurrents far in excess of the specified trip setpoint values.
These values are based upon protecting the associated electrical eculpment inside containment.
However, this is not a safety consideration, since the function of the eoulpment would also be lost when the breaker opened.
Licensee Actions Related to the Alleged Violation:
A proposed Technical Specification change was submitted on May 9,
- 1985, which would explicitly reference our testing method as well as provide other changes to the subject Technical Specification.
No procedure changes have occurred because hbp-2-3850 already fulfills its function in the best known method.
Should you have any cuestions is this regard, please contact this office Very truly yours, 8 7' 4 m L. T. Gucwa REB /
xc:
J. T. Beckham, Jr.
-H.
C. Nix, Jr.
J. F. Stoltz (W C-NRR)
Senior Resident Inspector, Plant Hatch
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