ML20024J216
| ML20024J216 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 10/07/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20024J214 | List: |
| References | |
| NUDOCS 9410120184 | |
| Download: ML20024J216 (3) | |
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UNITED STATES
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E NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 20665 4 001
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f SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.179 l
TO FACILITY OPERATING LICENSE NO. DPR-65 NORTHEAST NUCLEAR ENERGY COMPANY THE CONNECTICUT LIGHT AND POWER COMPANY THE WESTERN MASSACHUSETTS ELECTRIC COMPANY MILLSTONE NUCLEAR POWER STATION. UNIT NO. 2
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DOCKET NO. 50-336
1.0 INTRODUCTION
By letter dated July 1, 1994, the Northeast Nuclear Energy Company (the l
licensee) submitted a request for changes to the Millstone Nuclear Power Station, Unit No. 2 Technical Specifications (TS).
The requested changes would change the TS associated with the sump recirculation actuation signal instrumentation.
The licensee will implement these changes after the i
installation of four auctioneered power supplies in the Engineered Safety Feature Actuation System (ESFAS) sensor cabinets during the forthcoming refuelling outage (Cycle 12).
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2.0 BACKGROUND
On July 6,1992, while the Millstone Unit 2 was in a refuelins outage, a loss of normal power occurred when two ESFAS sensor cabinets were de-energized during a simultaneous replacement of two 120 volt Class IE inverters supplying l
ac power to the ESFAS cabinets. A subsequent review of the ESFAS circuitry by i
the licensee indicated that a Sump Recirculation Actuation System (SRAS) signal would be generated if control power was lost to two specific combinations of two-out-of-four ESFAS sensor cabinets.
The present SRAS instrumentation used four channels (A, B, C, and D), each j
powered from one instrument panel VA 10, VA 20, VA 30, and VA 40. The two-out-of-four SRAS logic permits six channel combinations, namely AB, AC, AD, BC, BD, and CD.
Loss of combination AC and BD could occur in the event of loss of a single 125 volt de power source. Such a loss of power would result in a spurious SRAS actuation.
If this were to occur during a loss-of-coolant accident (LOCA), a low pressure safety injection pump required for LOCA mitigation would be stopped by the SRAS signal.
In addition, in the event of an LOCA or main steamline break, such an SRAS actuation could open the containment sump recirculation motor operated valve before the refueling water 9410120184 941007 PDR ADOCK 05000336 P
. i storage tank inventory is injected into thereactor coolant system.
Therefore, for the short-term, the licensee modified the SRAS logic to eliminate the two i
undesired permissives and by letter dated October 28, 1992, the licensee proposed the necessary TS changes to implement the hardware changes.
On December 23, 1992, the NRC approved those TS changes as Amendment No. 168.
For the long-term, the licensee proposes to use auctioneered power supplies to the ESFAS sensor cabinets.
This modification will restore the SRAS logic to its original state.
In addition to the auctioneered power supplies, the licensee in 1992 installed manual main steamline isolation (MSI) trip buttons.
3.0 EVALUATION The proposed changes involve the auctioneering ESFAS sensor cabinet power supplies, SRAS logic circuit modifications, and MSI manual trip button addition.
TS changes associated with the incorporation of the auctioneering ESFAS sensor cabinet power supplies are specified in a new TS page 3/4 3-25a.
This page specifies:
a.
The normal and backup p1.ser supplies for different cabinets will be as specified in Table 3.3-Sa.
b.
In the event any of the ESFAS sensor cabinet power supply (ies) is inoperable, or either the normal or backup power source is not available, the inoperable power supply (ies) must be restored to operable status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or the plant will be in cold shutdown within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.
This requirement conforms with the standard Technical Specifications for Combustion Engineering plants, NUREG-1432, and on December 23, 1992, NRC approved similar changes for the temporary TS of Millstone Unit 2 (Amendment 168).
c.
Make visual inspection of the power supplies of the ESFAS cabinets once per shift.
d.
Verify the operability of the auctioneering circuit at least once per 18 months.
This requirement conforms with similar requirements for comparable ESFAS instrumentation of NUREG-1432.
The TS changes associated with the SRAS logic modifications are marked on pages 3/4 3-13, 16, and 17 (Table 3.3-3).
On page 3/4 3-13, minimum number of operable channels will be changed from 4 to 3 as a result of installation of the auctioneering power supplies which will permit operation with 2-out-of-3 logic.
On page 3/4 3-16, Note (f) has been deleted as this note is not applicable after installation of the auctioneering circuit.
On page 3/4-17, Action 4 will be revised to permit 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for surveillance testing of an additional channel when the minimum operable channel requirement is met.
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. The TS changes associated with the main steamline ise'stion are marked on i
pages 3/4 3-13, 18, and 23.
These changes are consistent with existing manual trip buttons for other ESFAS logics and the Standard Technical Specifications.
Based on the staff's evaluation, the staff concludes that there is sufficient assurance that the proposed changes do not degrade or adversely affect the plant safety system and are acceptable.
4.0 SIATE CONSULTATION In accordance with the Commission's regulations, the Connecticut State official was notified of the proposed issuance of the amendment.
The State official had no comments.
5.0 ENVIRONMENTAL CONSIDERATION
The amendment changes a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The NRC staff has determined that the amendment involves no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Commission has previously issued a proposed finding that the amendment involves no significant hazards consideration, and there has been no public comment on such finding (59 FR 42342). Accordingly, the amendment meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.
6.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
S. Mazumdar Date:
October 7, 1994 l
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