ML20137S514
| ML20137S514 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 09/20/1985 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20137S512 | List: |
| References | |
| NUDOCS 8509300405 | |
| Download: ML20137S514 (6) | |
Text
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UNITED STATES
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~,j NUCLEAR REGULATORY COMMISSION L
p WASHINGTON, D. C. 20555
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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 92 TO FACILITY LICENSE NO. DPR-71 AND AMENDMENT NO. 117 TO FACILITY LICENSE NO. DPR-62 CAROLINA POWER & LIGHT COMPANY BRUNSWICK STEAM ELECTRIC PLANT, UNITS 1 AND ?
DOCKET NOS. 50-325 AND 50-324
1.0 INTRODUCTION
By letter dated December 10, 1984 as. supplemented June 28, 1985, the Carolina Power & Light Company (the licensee) submitted proposed changes to the Technical Specifications 1T5) appended to Facility Operating License t
Nos. DDR-71 and UPR-62 for the Brunswick Steam Electric Plant, Units 1 and 2.
The proposed changes modify the TS to upgrade TS Sections 3/4 8.2.3 and 3/4 8.2.4 to reflect the Brunswick direct current (DC) system design and 1
load profiles. Administrative changes have also been made.to Section 3/4 8.2.5.
These changes are an outgrowth of the events described below.
In November 1983, Battery 2A-2 failed a routine 18-month load profile surveillance test. Though the battery was successfully retested on December 4
31, 1983, a detailed load study along with an extensive review of the DC system and the existing Technical Specifications (TS) for the system was made to verify the adequacy of the design and the appropriateness of the surveillance program. As a result of this study, the licensee determined that some existing TS could be revised to more readily identify degraded conditions and provide appropriate guidance to operate.
2.0 EVALUATION The changes to the TS for the DC Distribution portion of the Electric Power System, proposed by the licensee in the December 10, 1984 application have been reviewed. Our evaluation below of each Limiting Condition of Operation (LCO) and Surveillance Requirement (SR) proposed by the licensee is identified by the TS section number.
The Brunswick design has unique DC systems which consist of four 125-vol't de systems per unit. Two of the 125-volt de systems fonn the Division 1 250-volt de power supply while other two form the Division II 250-volt de i
power supply. The current TS and the Standard Technical Specification (STS) were designed for a unitized, fully separate 125/250-volt de system.
However, the Brunswick plant has unique system design for 125-volt de power supply with flexibility to enhance the availability of power to the equipment and the systems. Certain circuits, including equipment of the 8509300405 850920 PDR ADOCK 05000324 P
125-volt dc system, are shared between the two Brunswick units. For instance, IA2, one of four 125-volt de systems supplies nomal DC power to DG-1, and distribution buses El, E5 and H58. When the nomal supply is not available. 2A1, one of four 125-volt dc systems of the othe'r unit is the alternate DC power supply to the above circuits through an automatic transferring scheme and is an independent power path.
If the nomal and the alternate power supplies, IA2 and 2A1, are not available, 2A2, the other 125-volt de system.of the same 250-volt division of the other unit is the third power supply through a manual transferring operation. Thus, the Brunswick design has three independent 125-vn1t de power supplies available to the ECCS equipment and circuits. Therefore, the normal STS LCOs for the 125-volt dc power supplies are not applicable to the Brunswick design whi,le the LCO for only 250-volt de power supplies are applicable. The LC0 for the 125-volt de power supplies is governed by the more restrictive LCO for its associated equipment and circuits. The LCO for the 125-volt de circuits will be discussed in the TS change for Section 3.8.2.4.1 below.
j (1) LC0 3.8.2.3 This section is reformatted to more closely conform with the standard Technical Specification for BWR, NUREG-0123 (STS). This is an administrative change and is acceptable.
(2) 3.8.2.3 Action Statements (a) Action Statement "a" is revised to reflect the DC system design. The DC system design at Brunswick consists of four 125 l
volt (V)de batteries and chargers per unit. Each of the 125 Vdc batteries and its associated charger provide 125 Vdc control and instrumentation power for the safety-reloaded loads. Two of the 125 Vdc batteries and their associated chargers are connected to l
form the Division I 250 Vdc power supply. The other two fom i
the Division II 250 Vdc power supply. Therefore, an inoperable i
battery and/or an inoperable charger renders the 250 Vdc division inoperable. The results of the licensee's analysis for the loss of one DC division reflect that sufficient Emergency Core Cooling System (ECCS) equipment is maintained to mitigate the postulated design basis events (DBE). Because the system has been analyzed for a complete loss of one division, the 7-day (LCO) is applicable regardless of the number of inoperable batteries and/or chargers 1
.in the one division. Therefore, Action Statement "a" is revised i
as a result of the above analysis. The statement: "With one battery, or one charger, or one battery and its associated charger" is changed to read "with one or more batteries and/or its associated charger." Any one of 125 Vdc inoperable batteries i
and/or inoperable chargers renders the 250 Vdc inoperable, and therefore the proposed change is acceptable.
(b) Action Statement "b" is revised to provide for the fact that loss of more than one division of DC power per unit could result in less than the minimum ECCS requirements. Therefore, an orderly shutdown of the Unit is warranted with both DC divisions declared 4
. inoperable. When one or more batteries and/or its associated 4
1-charger in both divisions is declared inoperable, the action statement requires hot shutdown without delay.
The proposed change i
to the action statement from a 3-day LCO to immediate shutdown with both divisions inoperable satisfies the NRC guidance provided in Regulatory Guide 1.93, and is therefore, acceptable.
i (c) Action Statement "c" has been deleted. With modification of the definition of an inoperable division as described in proposed 3.8.2.3 Action Statement "a" above, the current Action Statement "c" is no longer required. The loss of one DC division is not applicable to the Brunswick system design because the current TS defines that a loss of one division includes loss of a single 125 Vdc supply and beyond.
Based on our evaluation of the 250/125-volt de systems design of Brunswick, as discussed above, the staff finds the proposed changes to Technical Specification 3.8.2.3 action statements acceptable.
l (3) SR 4.8.2.3.1 This section is revised to add verification that not more than two 37.5 Kilovolt amperes (KVA) power conversion modules are aligned to the "B" division bus. The "B" division dc power system provides the normal i
feed to the lighting and communication inverter for its respective unit.
It also provides the alternate feed to the plant uninterruptable
. power supply (UPS) (nonnally fed from "A" division) and the opposite 1
l unit lighting and communications inverter. The licensee's load study i
reflects that the resultant value of all three of the 37.5 KVA power j
conversion modules aligned to the "B" division de system batteries during the design basis accident (DBA) could exceed the 916 ampere
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limit in the TS change proposed for Section 4.8.2.3.2.
The proposed TS i
change places a restriction to allow a maximum of two inverters to be
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fed from the "B" division batteries at the same time and is, therefore, acceptable, i
4 (4) SR 4.8.2.3.2 The licensee has performed a detailed DC system load study. The study 1
reflects that 60-second loading values are less than the 916 ampere maximum value. The first 1-minute duty cycle profiles were formulated in accordance with IEEE-458-1983, IEEE-308-1971 and other j
committed design codes and standards. Therefore, the recomended test value of 916 amperes for the first 60 seconds of the profile test, demonstrates the battery's capability to adequately supply the worst
)
case ampacities.
The recomended test values for the remainder of the first 30 minutes and the remainder of the 4-hour test are much greater than duty cycle profile ampere values. The test values for the remainder of the 4-hour l
test in the proposed change are more than double the test values for l
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. the 8-hour test of the current TS. Also, the total test time of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> was selected as an adequate time to notice any signs of the battery capacity degradation.
(a) SR 4.8.2.3.2 a and SR 4.8.2.3.2 b The present 7-day and 92-day surveillance requirements determine the battery and charger's operability with those specified in the STS. The proposed changes to TS 4.8.2.3.2 a and 4.8.2.3.2 b are consistent with the criteria statements reviewed above and are therefore, acceptable.
(b) SR 4.8.2.3.2 c The footnote for the one-time-only exception, currently included in this section, is proposed to be deleted. This is an administrative change to remove an obsolete statement and is therefore acceptable.
(c) SR 4.8.2.3.2 d The licensee provided information related to the 125-volt de batteries, lead-calcium ty The battery's uncorrected plant rating (pe, Gould Model NEX-1200.
before correcting for aging, temperature, and design margin per IEEE 485-1983) correlated to a maximum ampacity value for the first-minute duty cycle profile equals 916 amperes.
Based on our evaluation of the load study and justification for the proposed changes to the loading profile, the staff concludes that the recommended test value of 916 amperes for the first 60-seconds of the profile test adequately demonstrates the '
battery's capacity to supply the worst case ampacities and the revisions made to the 30-minute and 4-hour test capacities are in all cases more conservative and restrictive than the previous capacities. Therefore, the proposed changes to TS 4.8.2.3.2 d are acceptable.
(d) 4.8.2.3.2 e.
The licensee proposed a change that the 60-month perfonnance discharge test supersedes the battery service test. This change is consistent with the other proposed changes and is, thgrefore, acceptable.
(5) Table 4.8.2.3.2 The proposed table provides the parameters to which the surveillance requirements of Section 4.8.2.3.2 must be performed. These parameters in Table 4.8.2.3.2 are consistent with the action statements and are, therefore, acceptable.
(6) LC0 3.8.2.4.1 The current TS treat the 125-volt and 250-volt de system as a unitized system and therefore provide the LCOs and surveillance requirements for
, one unitized 125/250-volt de system.
As described in the above evaluation, the 250-volt de divisions are not shared, while certain circuits of the 125-volt de systems are.
The 125-volt de systems (divisions) are shared between units, because they provide 125-volt de control power for the onsite Class IE alternating current (AC) power distribution system. The onsite Class IE AC power distribution system, e.g., diesel generator, is shared between units in that three of the four AC divisions between the two units are required to maintain the minimum ECCS requirements. When the de control power for diesel generators, 4160V emergency. buses, 480V emergency buses, or ESS logic cabinets is transferred to its alternate source, a single failure to the DC system could make two of the four AC divisions inoperable. The LCO for the safety function of the circuits is more restrictive than the LC0 for the 125 Vdc power supplies. Also, the LC0 in the present TS for the 125-volt de power supply (division) is not applicable to the Brunswick design because a given circuit has two normal and one alternate 125-volt de power supplies. Therefore, the proposed surveillance requirements of these circuits in the plant TS will provide control of the transfer and provide added assurance of de power availability.
Based on our evaluation of the 125-volt dc power design, the staff concludes that the proposed changes accurately reflect the Brunswick design and are acceptable, i
3.0 S'JMMARY We have reviewed the above licensee proposed changes. We find that the proposed changes to the TS will more accurately reflect the plant design and also ensure that the DC systems are fully tested within the design limits of the system and are therefore acceptable.
4.0 ENVIRONMENTAL CONSIDERATION
S The amendments involve a change in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and change in surveillance requirements. The staff has detennined that the amendments involve 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 Coninission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public comment on such finding.
Accordingly, the amendments meet 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 amendments.
5.0 CONCLUSION
We have concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of th'e public will not be endangered by operation in the ' proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations and the issuance of the amendments will not be inimical to'the common defense and security or to the health and safety of the public.
Principal Contributor:
S. Rhow Dated: September 20, 1985 9
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