ML20070U002
| ML20070U002 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 01/18/1983 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20070T991 | List: |
| References | |
| NUDOCS 8302100104 | |
| Download: ML20070U002 (5) | |
Text
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UNITED STATES g
NUCLEAR REGULATORY COMMISSION j
WASHINGTON. D. C. 20555 g.g J [g t i ' %,/
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r SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR PEGULATION SUPPORTING AMENDMENT NO. 62 TO e
FACILITY OPERATING LICENSE NO. DPR-69 BALTIM0RE GAS AND ELECTRIC COMPANY CALVERT CLIFFS NUCLEAR POWER PLANT UNIT N0. 2 DOCKET N0. 50-318 Introduction By application dated November 5, if 82, as supplemented by letter cated November 17, 1982, Baltimore Gas and Electric Company (BG&E) requested changes to the Technical Specifications (TS) for Calvert Cliffs Unit 2.
The proposed changes to the TS would provide Limiting Conditions for Operation (LCO) and Surveillance Requirements (SR) which reflect the operability of a recently installed third train of the auxiliary feed-water system.
Discussion BG8E has implemented a number of changes to the Calvert Cliffs Unit 1 and as Unit 2 auxiliary feedwater systems in response to the NRC's TMI Action Iter.s (NUREG-0737). Among the most significant of such changes involves the addition of a third train, to' the auxiliary feedwater systems, which is provided with a motor driven pump rated at 450 gpm. The original two trains of auxiliary feedwater are provided with steam-driven turbine pumps each rated at 700 gpm.
Upon reaching a low steam generator level.
setpoint, the auxiliary feedwater actuation system (AFAS) will automatically initiate auxiliary feedwater using one steam turbine powered and one motor powered, auxiliary feedwater pump.* The instrumentation and control features of thi's system were reviewed and approved by our letter dated June 21, 1982.
As a result of. recent progress on the auxiliary feedwater modifications during the Fall 1982, Unit 2 refueling catage, these modifications to the Unit 2 auxiliary feedwater system are now complete. Accordingly, BG&E has evaluated the safety significance of operating Calvert Cliffs Unit 2 with the modified auxiliary feedwater system.
In addition, BG&E' has proposed.a revised LC0 and SR which requires demonstrated operability l
.of the motor driven auxiliary feedwater train.
- The second steam-driven auxiliary feedwater pump would be prevented from automatically supplying auxiliary feedwater.
l 8302100104 830118
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PDR ADOCK 05000318 i
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, Evaluation The November 17, 1982 letter from BG&E addressed the three Design Basis Events (DBEs) which are affected by the automatic actuation of the modi-fied auxiliary feedwater system.
The three DBEs - loss of feedwater, feed line break, and steam line break-were analyzed with and without loss of AC power (LOAC) on turbine trip -
to ensure that relevant acceptance criteria continue to be met in light of the new AFAS logic.
A spectrum of feedwater and sgeam line break sizes were anclyzag. The worst break size was 0.275 ft for the feedline break, 6.305 ft for steam line break inside containment and 0.33 ft2 for steam i The0.275ftgnebreak outside' containment with LOAC on turbine trip.
feed line break downstream of the check vaive with LOAC on turbine trip resulted -
in the highest reactor coolant systen peak pregsure but did not exceed the pressure limit of 2750 psia. The 6.305 ft steam line break inside containment resulted in the maximum post trip return to power and minimum DNBR. gowever, the DNBR still was above the design limit of 1.23.
The 0.33 f t ' steam if ne break outside cantainment resulted in the maximum number of predicted fuel pin failures where 2% of fuel pins experienced DNB.
However, the resulting site boundary dose was well within the 10 CFR 100 guidelines. The result of the loss of feedwater flow event c
with and without loss of AC following reactor trip showed that the peak pressure did not exceed the upper limit of 2750 psia and that an adequate heat sink was maintained during the event.
Based upon the above, we conclude that the consequences of the DBEs, in terms of an acceptable level of fuel failure and primary system integrity, are acceptable for automatic initiation of the modified auxiliary feed-water system.
Technical Specification The Bases for TS 3/4 7.1.2, " Auxiliary Feedwater System", has been changed as a result of the modifications to the auxiliary feedwater system. The existing TS 3/4 7.1.2 is based upon two steam driven auxiliary feedwater pumps which are automatically started with flow controlling valves (1/2-CV-4512) preset to supply between 100 and 130 gpm. This configura-
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tion allows u~p to 20 minutes for the reactor operator to terminate auxiliary feedwater flow in the event of an overcooling transient *, or
- Continued auxiliary feedwater flow, if unnecessary, could result in an overcooling transient which.might cause an emergency core cooling actua-tion.
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, to increase auxiliary feedwater flow to maintain an adequate heat sink.
The revised TS 3/4 7.1.2 is based upon automatic actuation of one steam driver, auxiliary feedwater pump and the motor driven auxiliary feedwater pump with the AFAS providing a modulated flow of 160 gpm (+ 10 gpm).
This increased flow, and other factors associated with the AFAS design, allows the operator up to 10 minutes to take action to increase, or isolate, auxiliary f.eedwater flow. These changes are reflected in the revised Bases for TS 3/4 7.1.2.
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The proposed TS 3.7.1.2 is consistent with the Bases in that the LC0 requires that one stear.: driven and one motor driven auxiliary feedwater pump be operable and available to start and provide flow upon initiation of the AFAS (automatic initiation mode).
In addition, the LC0 requires that the second steam driven pump be operable in its standby mode. A footnote explains that " standby" requires that the pump be operable; however, automatic starting of the pump is defeated upon AFAS at.tuation.
The above LCO provides a reliable auxiliary feedwater source of 160 gpm
(+ 10 gpm). As indicated in Bases 3/4 7.1.2, "A [ auxiliary feedwater]
capacity of 400 gpm is sufficient to ensure that adequate feedwater flow is available to remove decay heat and reduce the Reactor Coolant System temperature to less than 300 F when the shuttfown cooling system may be placed in operation " The required flow rate of 400 gpm can be accom-e modated by the motor driven feedwater pump, alone. The LC0 is within the bounds of the safety analysis and is therefore acceptable.
s The remedial actions to be taken, should the requirements of TS 3.7.1.2 not be met, have been modified t'o reflect the addition of the motor driven auxiliary feedwater pump. At.the present time, TS 3.7.1.2 requires that an inoperable steam driven auxiliary feedwater pump be returned to s.ervice within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the plant shall be placed in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. The proposed remedial action for the motor driven auxiliary feedwater pump is the same as was previously required for the inoperability of a steam driven auxiliary feedwater pump. The proposed remedial action for a single inoperable steam driven auxiliary feedwater pump is to:
(1) align the operable steam driven pump to automatic initiating status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, and (2) restore the iaoperable steam driven pump to operable status within 30 days or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The above r'emedial requirements assure that, except for periods of up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, at least two auxiliary feedwater trains are available to e
provide automatic initiation of auxiliary feedwater. Thus, as indicated above, the auxiliary feedwater system can reliably perform its design function to deliver at least 400 gpm to maintain an adequate heat removal capability.
In addition, since no additional safety concerns are asso-ciated with changing operational modes with an inoperable steam driven auxiliary feedwater pump, no prohibition on 'such mode changes is appro-priate.
Based upon the above, proposed TS 3.7.1.2 is acceptable.
The Surveillance Requirements of TS 4.7.1.2 have been proposed for modi-fication to reflect changes to the auxiliary feedwater flow control.
Prior to modification, auxiliary feedwater flow was controlled via preset flow control valves.
These valves were the subject of surveillance to assure that their position would permit a flow of between 100 and 130 gpm. Specifically, TS 4.7.1.2.d required reverification of an auxiliary feedwater flow of between 100 and 130 gpm should the auxiliary feedwater flow ' control valves (1/2-CV-4511 and/or 1/2-CV-4512) be repositioned.
Since these preset flow control valves have been replaced by air-operated modulating valves, this surveillance is no longer applicable.
In place of TS 4.7.1.2.d, BG&E has proposed a requirement to perform a flow veri-fication test (proposed TS 4.7.1.2.c) each 18 months which would assure
'that each auxiliary feedwater pump delivers u modulated flow of 160 gpm
(+ 10'gpm) upon automatic initiation.
In addition, BG&E has proposed a tist of the dynamic head for the motor driven auxiliary feedwater pump (proposed TS 4.7.1.2.a.2).
This proposed test would be conducted every c
31 days to assure a dynamic head of at least 3100 ft on recirculation
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flow.
This test frequency is consistent with dynamic head test currently required for the steam driven auxiliary feedwater pumps.
Our review of the proposed TS 4.7.1.2 indicates that the modified sur-veillance requirements provide assurance that the auxiliary feedwater system will be maintained with sufficient capacity to meet the opera-bility requirements of the LCO (TS 3.7.1.2).
Accordingly, we find this TS to be acceptable.
Environmental Consideration ~
We have determined that the amendment does not authorize a chang'e in effluent types or total amounts nor an increase in power level and will not result in any significant environmental impact. Having made this determination, we have further concluded that the amendment involves an action which is insignificant from the standpoint of environmental impact and, pursuant to 10 CFR 51.5(d)(4), that an environmental impact statement or negative declaration and environ-wental impact appraisal need not be prepared in connection with the issuance of the amendment.
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. t Conclusion We have concluded, based on the considerations discussed above, th'at:
(1) there is reasonable assurance that the health and safety of the 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.
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Date:
January 18, 1983 Principal Contributors:
D. H. Jaffe A. Gill e
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