ML20078R827
| ML20078R827 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 11/10/1983 |
| From: | Lundvall A BALTIMORE GAS & ELECTRIC CO. |
| To: | John Miller Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8311150315 | |
| Download: ML20078R827 (6) | |
Text
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,t BALTIMO RE GAS AND ELECTRIC i
CHARLES CENTER P.O. BOX 1475 BALTIMORE, MARYLAND 21203 i
k Anmua c. LuwovAu Ja.
November 10,1983 VICE Pitt$1 DENT Supply Director of Nuclear Reactor Regulation Attention: Mr. 3. R. Miller, Chief Operating Reactors Branch #3 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555
Subject:
Calvert Cliffs Nuclear Power Plant Units Nos.1 & 2; Dockets Nos. 50-317 and 50-318 Auxiliary Feedwater System Technical Specification
Reference:
(a) BG&E letter from Mr. A. E. Lundvall, Jr., to Mr. 3. R. Miller (NRC), dated September 16,1983.
Gentlemen:
Reference (a) requested, in part, that the Bases for Technical Specification 3/4.7.1.2 be revised to reflect the configuration of the upgraded auxiliary feedwater system (AFWS). Included in the proposed bases was a recognition of the automatic flow-controlling characteristics of the system. To ensure continued familiarity _with system performance _ characteristics on the part of the control room operators and p(lant engineering and maintenance personnel, we proposed to identify in the bases for information only) the nominal AFWS flow setpoint that would normally be employed. We also identified the error Isand that was associated with this setpoint.
1 he purpose of this letter is to revise the values of the nominal flow setpoint and instrument loop error band provided by Reference (a). A new nominal flow setpoint of 200 gpm has been selected from a review of recent preoperational test results strictly l
on the basis that the new modulating valves appear to control flow more steadily at this setpoint. Also, new instrument loop error bands of plus 25 gpm and minus 26 gpm for the motor driven pump train and plus 37 gpm and minus 40 gpm for the steam-driven pump trains have been calculated and should be included in the revised technical specification bases.
He proposed revision to page B 3/4 7-2 of the techincal specifications is attached.
i Neither the nominal flow control setpoint nor the associated instrument loop error bands are pertinent to the results of the safety analyses performed to evaluate the ability of the AFWS to mitigate the effects of undercooling or overcooling transients. As indicated in Reference (a), an auxiliary feedwater flow of anywhere between 0 gpm and 1300 gpm (runout flow),' inclusive for the first 10 minutes of the worst undercooling or overcooling transient, respectively, will maintain plant response within the applicable regulatory acceptance criteria. This conclusion is based on licensing grade transient analyses, the results of which comprise the basis for T.S. 3/4.7.1.2.
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Mr. 3. R. Miller Novembzr 10,1983 i
Given these results, we feel that an additional requirement to verify flow to a -
specific value inside the range of values that has already been demonstrated to be acceptable by conservative safety analyses is inappropriate for inclusior. In the technical specifications.. Dis position is consistent with current NRC policy for identifying plant
- operating characteristics subject to coverage by technical specifications. This policy states in part, that:
... the fundamental purpose of technical specifications is to define and preserve those underlying assumptions that are
. expected to, or could, vary with time or circumstances, throughout the life of the plant, and thus to preserve the validity of the safety analysis."
Auxiliary feedwater flow at or near the nominal setpoint during the first 10
. minutes of the worst transient is neither an underlying assumption nor required to preserve the validity of the safety analysis. The ten-minute period is only raised as a point of discussion because, consistent with current regulatory guidance, no credit is taken for operator action for the initial-10 minutes of the transient. - As a practical matter, we encourage our operators to monitor primary system cooldown rate very early in a transient and to take. manual control of auxiliary feedwater flow as soon as possible.
Consistent with the definition of an operable auxiliary feedwater system in the proposed T.S 3.7.1.2 (which states that the system is capable of automatically initiating flow) we have proposed a~ surveillance requirement (T.S. 4.7.1.2.c) designed to demonstrate that the system will automatically start upon receipt-of an auxiliary feedwater actuation test signal. Since the delivery of any water to the steam generator i
- during the first 10 minutes of an undercooling transient is in excess of the amount that is required for an orderly cooldown and since verification of automatic initiation adequately demonstrates that the automatic features of the AFWS are operable, we conclude that the proposed surveillance requirement provides sufficient and continued y~~
assurance that the limiting condition for operation regarding automatic flow initiation will be met.
As discussed above, the AFWS is designed to allow the operators to manually adjust auxiliary feedwater flowrate as needed to facilitate an orderly cooldown. he system is capable of providing up to 450 gpm flow. To assure that the capability to-manually initiate' and control feedwater flow does not degrade during plant life, the technical specification requires a total dynamic head test of the pumps, a test 'of remotely operated valves in the flow path, and a line-up check of manual valves in the
- flow path.
Dese actions are those that we consider to be necessary and sufficient for verifying the capability of the AFWS to deliver the full range of flows for which it was designed.
However, we -understand from recent discussions with our NRC Project p
- Manager that you will insist upon the inclusion of a specified nominal AFWS flowrate as a part of the surveillance testing requirements of Section 4.7.1.2.
A surveillance requirement implementing this flow verification test was the subject of a discussion with Mr. D. Jaffe on November 8,1983 (see attached markup of T. S. page 3/4 7-Sa).
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3-Novcmbtr 10,1983
'Mr. 3. R. Miller
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Please be advised that we continue to hold a differing opinion on this matter but that we do not plan to object to your action.
If you should have any questions, please do not hesitate to contact us.
Sincerely,,
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Attachment cc: 3. A. Biddison, Jr., Esq.
G. F. Trowbridge, Esq.
Mr. D.' H. Jaffe, NRC Mr. R. E. Architzel, NRC N
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O plus 113pm and minus 40yn PLANT SYSTEM i
BASES U = maximum number of inoperable safety valves per operating steam line 106.5 = Power Level-High Trip Setpoint for two loop operation 46.8 = Power Level-High Trip Setpoint for single loop operation with two reactor coolant pumps operating in the same loop X = Total relieving capacity of all safety valves per steam line in Ibs/ hour Y = Maximum relieving capacity of any one safety valve in Ibs/ hour 3/4.7.1.2 AUXILIARY FEE 04ATER SYSTEM The OPERABILITY of the auxiliary feedwater system ensures that the Reactor Coolant System can be cooled down to less than 300 F from normal operating conditions in the event of a total loss of offsite power. A capacity of 400 gpm is
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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 shutdown cooling system may be placed into o eration.
Flow control valves,Unstall_ed in ach leg supplying the steam generators, are set to maintain a nominal flow setpoin of gpm plus or minus 10 gpm for operator I
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setting band. The nominal flow setpoint of gpm incorporates a total Instrument loop
, error band ofp!u: gp-W -Mu: 60 ;;p-$ The operator settinst band, when combined
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, with the instrument loop error, results in a total flow band oQ^ gp
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gi,m huhum). Safety analyses show that more flow during an overcooling transient and less flow during an undercooling transient could be tolerated; i.e., flow fluctuations outside this flow band but within the assumotions used in the analyses IIsted below, are dllowable.
In the spectrum of events analyzed in which automatic initiation of auxillary feedwater occurs, the following flow conomons are allowed with an operator action time of 10 minutes, f
(1)
Loss of Feedwater:
0 gpm Auxiliary Feedwater Flow (2)
Faedline Break:
0 gpm Auxiliary Feedwater Flow D)
Main Steam Line Break:
1300 gpm Auxiliary Feedwater Flow (This being the maximum flow through the AFW suction line, with one unit requiring flow, prior to pump cavitation due to low NPSH.)
At 10 minutes after an Auxiliary Feedwater Actuation Signal the operator is assumed to be available to increase or decrease auxiliary feedwater flow to that required b existing plant conditions.
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PLANT SYSTEMS BASES U = maximum number of inoperable safety valves per operating steam line 106.5 = Power Level-High Trip Setpoint for two loop operation 46.8 = Power Level-High Trip Setpoint for single loop operation with two reactor coolant pumps operating in the same loop X = Total relieving capacity of all safety valves per steam line in ibs/ hour Y = Maximum relieving capacity of any one safety valve in Ibs/ hour 3/4.7.1.2 AUXILIARY FEEDWATER SYSTEM The OPERABILITY of the auxiliary feedwater system ensures that the Reactor Coolant System can be cooled down to less than 300 F from normai operating conditions in the event of a total loss of offsite power. A 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 shutdown cooling system may be placed into operation.
Flow control valves, installed in each leg supplying the steam generators, are set to maintain a nominal flow setpoint of 200 gpm plus or minus 10 gpm for operator setting band. The nominal flow setpoint of 200 gpm incorporates a totalinstrument loop error band of plus 25 gpm and minus 26 gpm for the notor-driven pump train. The corresponding values for the steam-driven pump train are plus 37 gpm and minus 40 gpm.
'Ihe operator setting band, when combined with the instrument loop error, results in a total flow band of 164 gpm (minimum) and 235 gpm' (maximum) for the motor-driven pump train. The corresponding values for the : team cr:ven purnp train are 150 gpm (minimum) and 247 gpm (maximum). Safety analyses show that more flow during an overcooling transient and less flow during an undercooling transient could be tolerated; i.e., flow fluctuations outside this flow band but within the assumptions used in the analyses listed below, are allowable.
In the spectrum of events analyzed in which automatic initiation of auxiliary feedwater occurs, the following flow conditions are allowed with an operator action time of 10 minutes.
(1)
Loss of Feedwater:
0 gpm Auxiliary Feedwater Flow (2)
Feedline Break:
0 gpm Auxiliary Feedwater Flow (3)
Main Steam Line Break:
1300 gpm Auxiliary Feedwater Flow (This being the maximum flow through the AFW suction line, with one unit requiring flow, prior to pump cavitation due to low NPSH.)
At 10 minutes after an Auxiliary Feedwater Actuation Signal the operator is assumed to be available to increase or decrease auxi!!ary feedwater flow to that required by existing plant conditions.
EM GW CALVERT CLIFFS UNIT 1 B 3/4 7-2 (PkbPoseh)
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f)
Whenever a subsystem /s (a subsystem consisting of one pump, piping, valves and
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controls in the direct !!ow path) required for operability is inoperable for the performance of periodic testing (e.g. manual discharge valve closed for pump Total Dynamic Head Test or Logic Testing) a dedicated operator /s will be stationed at the local station /s with direct communication to the Contro!
Room. Upon completion of any testing, the subsystem /s required for operability
,i will be returned to its proper status and verified in its proper status by an independent operator check.
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d.
'The requirements of Specification 3.0.4 are not applicable whenever one motor l
and one steam-driven pump (or two steam-driven pumps) are aligned for I
automatic flow initation.
I PLANT SYSTEMS AUXILIARY FEEDWATER SYSTEM SURVEILLANCE REOUIREMENTS 4.7.1.2 Each auxiliary feedwater flowpath shall be demonstrated OPERABLE:
At least once per 31 days by:
a.
1.
Verifying that each steam-driven pump develops a Tota! Dynamic Head of 12300 ft. on recirculation flow (if verification must be demonstrated during startup, surveillance testing shall be performed upon achieving an RCS g
temperature 2,300.F and prior to entering MODE 1).
2.
Verifying that the motor-driven pump develops a Total Dynamic Head of 23100 ft. on recirculation flow.
3.
Cyc!!ng each testable, remote-operated valve that is not in its operating position through at least one complete cycle.
4 Ver!fying that each valve (manual, power operated or automatic) in the direct flow path is in its correct position, b.
Before entering MODE 3 after a COLD SHUTDOWN of at least 14 days by completing a flow test that verifles the flow path from the condensate storage tank to the steam generators.
c.
At least once per 13 months by :
I f, }/e,;fying /40/ ecc4 ado *0At. Val /e /0 0 No") po'% deriM NS so //.s correc&
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is es p jf,of p w !'d/'y a m inin u n of 200fpn tjominal,lk) -/c g f/og
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