ML20098H182
| ML20098H182 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 09/10/1984 |
| From: | Dale L MISSISSIPPI POWER & LIGHT CO. |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| AECM-84-0533, AECM-84-533, NUDOCS 8409120089 | |
| Download: ML20098H182 (3) | |
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MISSISSIPPI POWER & LIGHT COMPANY Helping Build Mississippi M
P. O. B OX 1640, J AC K S ON, MIS SIS SIP PI 3 9 2 05 NUCLEAR LICENSING & SAFETY DEPARTMENT U. S. Nuclear Regulatory Commission Office of Nuclear Reaccor Regulation Washington, D. C.
20555 Attention:
Mr. Harold R. Denton, Director
Dear Mr. Denton:
SUBJECT:
Grand Gulf Nuclear Station Units 1 and 2 Docket Nos. 50-416 and 50-417 License No. NPF-13 File: 0260/15180/L-860.0 Addition of Overcurrent Protection to Technical Specifications AECM-84/0433 Mr. Thomas M. Novak, in a letter dated August 28, 1984, requested information regarding the circumstances by which certain circuit breakers were added to the Grand Gulf Technical Specifications (GGTS) after completion of the Technical Specification Review Program (TSRP) and actions taken by Mississippi Power & Light Company (MP&L) to assure that these subsequent additions were not indicative of a weakness in the TSRP. This letter provides the requested information.
In March, 1984, while the TSRP was in progress, MP&L concluded that additional surveillances on certain low voltage circuit breakers, which provide overcurrent protection to primary containment electrical penetrations, should be included in the GGTS. Af ter an evaluation by MP&L of this matt ar and following discussions with members of your staff, it was agreed that the additional surveillances were appropriate and these circuit breakers should be added to the GGTS. All circuits which penetrate containment and can develop sufficient fault current to damage containment penetrations require a second level of overcurrent protection to comply with Regulatory Guide (RG) 1.63 (as described in FSAR Q&R 040.5). Therefore, MP&L compiled a table of the circuit breakers associated with those low voltage circuits penetrating containment, which were shown on the plant's design documents to have a second level of overcurrent protection, for inclusion in the GGTS. MP&L then formally requested the addition of these circuit breakers to the GGTS by letter dated June 21, 1984. At the time the table was compiled, a detailed review of circuit design for adequacy of overcurrent protection was not performed.
In early August 1984, during a circuit design review, conducted independent of the TSRP and not otherwise associated with the GGTS, MP&L determined that various low voltage circuits which penetrate containment did not have the required degree of overcurrent protection and, therefore, did not conform to the FSAR description of acceptable circuit design. MP&L's evaluation determined that 10 of those circuits, although they had redundant overcurrent protection, did net comply with the FSAR. Therefore, these 10
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~ ircuits were modified to add an additional level of overcurrent protection.
c The' design, discrepancy associated.with the 10 circuits was not safety significant in that the 10 circuits had upstream (not downstream as committed to in the FSAR)'breakeri rotection that would have provided a second level of p
overcurrent. protection. =The circuit breakers associated with these 10 circuits needed to be added to the GGTS. Accordingly, MP&L requested this addition to.the GGTS by a letter: dated. August 14, 1984.
'For the. remainder of.the circuits not conforming to the FSAR description, an evaluation was conducted by MP&L to determine appropriate corrective actions.. All of these remaining circuits supported loads which were not required for current or future plant operations. Therefore, these circuits-were permanently isolated (physically disconnected) and, accordingly, were not requiredL to be' included in the plant's technical specifications. Furthermore, MP&L determined that these circuits would not have-adversely affected safe operations'had the condition remained uncorrected. The design discrepancy associated with these circuits and the absence of the 10 other circuits from the technical specifications are not safety significant.
Subsequent'to the determination of the existence of the nonconforming low voltage circuits, MP&L conducted a complete review of all circuits penetrating the primary containment to ensure compliance with.RG 1.63 and the FSAR-
' description of penetratior. protection. No additional discrepancies were found. 'Aa a result of these revices, MP&L believes this to be an isolated occurrence related only to the design of these particular circuits.
=The purpose of the TSRP was to provide a two-pronged comparison, (1) between the GGTS.and FSAR and-(2) between the GGTS and the as-built plant.
The TSRP provided MP&L with confidence that the GGTS accurately reflects both the FSAR and.the as-built plant. ~ The circuit design discrepancies were not
-identified in the TSRP because they involved an inconsistency between the plant design and the FSAR rather than a technical specification inconsistency.
Therefore, the determination of the need for these design modifications did not indicate a weakness in the TSRP.
In summary, the TSRP was established to review the technical specifica-tions against the Grand Gulf as-built-plant and against the FSAR. As a result of the TSRP, low voltage circuit breakers meeting certain criteria were proposed'for addition to the technical specifications as an enhancement to the surveillance program at Grand Gulf. However, because the design documents used as the basis for determining plant design versus technical specification consistency contained the discrepancy described above, these circuits were not identified during the TSRP as meeting the criteria for inclusion in the GGTS.
On the basis of a-thorough circuit design review and engineering evaluations of this issue, MP&L does not consider-the design discrepancy to be of safety
- significance or the resulting addition of these circuits to the GGTS to be
' indicative of's weakness in the TSRP or in the Grand Gulf design control and verification program.
Furthermore, Bechtel Power Corporation, responsible for the balance of plant portion of the TSRP, has also reviewed the circumstances surrounding this issue and following an evaluation, has indicated that this occurrence
- does not reduce their confidence in ths TSRP.
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AECM-84/0433 MCTISSIPPI POWER & Ll2HT COMPANY
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MP&L' continues to have the highest confidence'in the conduct and outcome of the TSRP. MP&L does not believe that the determination of the existence of this design discrepancy brings into question the validity of the TSRP or any representations made by MP&L as to the adequacy and accuracy of the GGTS.
Yours truly, L. F. Dale Director LFD:rg cc:
Mr. J. B. Richard Mr.-R. B. McGehee Mr. N. S. Reynolds Mr. G. B. Taylor Mr. Richard C. DeYoung, Director Office of~ Inspection & Enforcement U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Mr. J. P. O'Reilly, Regional Administrator U.S. Nuclear Regulatory Commission Region II 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323