ML030870874
| ML030870874 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 11/21/2002 |
| From: | Dresche C, Harper R, Hoefert N Nuclear Management Co |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2003-0094 PBF-1553, Rev 9 | |
| Download: ML030870874 (8) | |
Text
Point Beach Nuclear Plant OPERABILITY DETER-MINATION PART I OPR 000031 CAP 029952 / 030040 /030209 REV 4
ENGFNEERING TO COMPLETE THiS BOX WHEN OD ACCEPTED BY DSS SYNOPSIS FOR NIM INFORMATION ONLY CHAMPS Unit(s) 0, 1, 2 System AF Equipment ID Various
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Inoperable - does not meet the minimum level ofperformance.
F-Operable - fully meets performance requirements. No further action required.
Operable But Degraded - or Operable But Nonconforming - meets the minimum required level of
[
performances, compensatory measures ARE required.
Operable But Degraded - or Operable But Nonconforming - meets the minimum required level of 0
performances, compensatory measures are NOT required.
Potential for simultaneous failure of all AFW pumps due to insufficient minimum pump flow TITLE (toQEMmfTNur UBmEx A*34o neeOprioN oP issu)
Revision 4 of this OD incorporates CAP 030209. The power to the AFP minimum-recirculaton s4 noid valves for I P-29 and 2P-29 and the control circuitry for motor driven pump P-38A (including the rolni recirculation valve for P-38A) ae all derived from 125VDC bus D-01. Evaluating this situation facda design basis accident or event combined with a single failure of equipment important to safety, coul#
challenge the operability of IP-29, 2P-29 and P-38A since the recirculation valves use a "fail closoe"I design. This issue would also result in essentially the same result as plugging the mini-recirculatiotif orifices.
Revision 3 of this 01 incorporates CAP 030040. The power to the AFP minimum-rccirculation soa noid valves is fed from a Safety Related DC power supply. This circuit's actuation is from a Non-Safety lated AC power source, Vital Instrunent Panel 1/2Y-06. The loss of the I20VAC power supply will cau : the mini-recirc valves to fail closed. Effectively the same result as plugging the mini-recirc orifice.
Revision 2 of this OD restored the original Revision 0 wording. The OD was reworded in Revision1 on Operations request to describe the problem in terms of loss of flow through the AF recirculation iio for any reason. Revision 2 restores the original wording of the problem statement to be a loss of flow throý h the AF recirculation line due to potential blockage of the orifice with material in the supply water.
Describe the condition.
During a plant transient, a combination of the existing plant design and operating-if procedures may result irtafailure mode of one or more AFWpumps.
When steam generator (SG) levels have been restored to desired levels following a transient, manual action is required to maintain those levels. This manual action,uld be accomplished by securing the associated pump(s), or by reducing flow to match; he steaming rate. It could also be accomplished by completely closing offflow to onel r both SGs if desired: this is likely to be the case if the desired level has been exceeded d to overfill, swell, etc. Isolating discharge flow to the SGs, could result in no flow thr' gh a running AFWpump since the recirculation line orifice passages are susceptible toi blockage particularly when the safety related SW is aligned as the suction source, his would cause very rapid failure of these multi-stage high pressure pumps PB F-Ion N
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As described in CAP 030040. a loss of l20V.4Cpowerfron Ltdl Insrrnmen: pane, Y-06 can result in noflow through a running AFtTpump dute to the recirculation line vcfve failing closed j
In addition, CAP 030209 describes a condition where a loss of 125VDC bus D-OI ould also fail the recirculation valves closed on IP-29. 2P-29 and P-38A
- 2.
Identify the Current Licensing Basis (CLB) functions and performance requirements including Tech Spec Reference 3.7.5 FSAR Reference 10.2. 7.3.3 4 NRC Commitment Reference Other 50 59 EVAL 2002-005, FCR 02-027, FCR 02 019 If no CLB function, requirement or commitment is affected, no further action is required. NIA Stej and 5 and proceed with Step 6.
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I!The AFWSystem shall be OPERABLE with one turbine driven AFW pump system <per Unit> and two motor driven AFWpump systems when in modes 1. 2. and 3 The bases
-or this Technical Specification states that "The AFWSystem automatically supplies Veedwarer to the steam generators to remove decay hear from the Reacto-Coolant Syvstem t.upon the loss of normal feedwater supply'".
FSAR Lhapter 10.2.1 The AFW system shall automatically start and deliver adequate AF system flow to
[maintain adequate generator levels during accidents which may result in main steam
.safery valve opening including: Loss of Normal Feedwater (LONF) and Loss ofAll AC
- Power to the Station Auxiliaries (LOAC) These accidents are evaluated in detail in sections 14.1.10 and 141.11 respectively
.The AFsystem is credited with automatically starting and delivering sufficient AFflow to
'Imaintain adequate steam generator levels during accidents which require rapid reactor
'coolant system cooldown to achieve cold shutdown condition within the limits of the hanalysis, including Steam Generator Tube Rupture (SGTR; FSAR Chapter 14.2.4), and
),Mfain Steam Line Break (,VSLB: FSAR Chapter 14.2.5).
The AF system shall be capable of isolating the AF steam andfeedwater supply lines from the ruptured generatorfollowing a SGTR event.
',The AF system also is capable of automatically supplying sufficient feedwater to remove iWeecay heat from both units without any reliance on ACpowerfor one hour (station btackout).
In the event ofplant fires, including those that require evacuation of the control room, the AF system shall be capable of manual initiation to provide feedwater to a minimum of "one steam generator per unit at sufficient flow and pressure to remove decay and
.sensible heat from the reactor coolant system over the rangefrom hot shutdown to cold Sshutdown conditions.
FSAR 10.2.2
- This section states that each pump has an AOV controlled recirculation line back to the
- ,condensate storage tanks to ensure minimum flow to prevent hydraulic instabilities and dissipate pump heat.
4, FSAR MO.2.3 1 Based on the operating characteristics of the minimum recirculationflow control 4 scheme, a portion a AFpumps discharge will be automatically recirculated back to the CSTs for approximately 45 seconds after the pump starts. The 45 second time delay in i closing the recirculation line control valves is incorporated in the design to provide for jpump stability and cooling during coastdown.
FSAR.3.3.4 ifa loss of instrument air occurs or an Auxiliary Feedwater Pump minimum flow urecirculation valve fails closed, manual operator action is required to prevent the
',potentialfailure of the pump(s). By procedure, the operator will either secure the running
- pump(s) or maintain forwardflow through the still running pump(s) to prevent pump damage that could be caused by overheating Backup pneumatic supplies are provided to all AFpump minimum recirculation valves.
These backup supplies are sized to provide adequate time for operators to either
.maintain minimum flow through the running pump(s) to secure the unneeded pump(s) if
,necessary to restore instrument air, or to use the manual gag on each valve to provide I minimum recirculationflow.
POINTEEACH PA:GE 4 12
11/ Z1, 2OUU Fii1 I
No related issues euXst lated AR Number CR 01-3648 ntpact eview of the condition described in section I of this OD indicates a potential for the loss ifaflowpathfor the MDAFWPs mirroring that described in OD CR 01-3648. OD CR
ý1-3648 describes a condition where an Appendix Rfire in Fire Areas AO1-B, A02. A23N Ind A23S, could result in the loss ofMDAFPfiowpath due to afire initiated auto-start of m MDAFP with a coincident loss of off-site power and instrument air. In each of the fire reas listed above, a MDAFP is relied upon as the means of delivering Aux Feedwater to i least one Steam Generator for at least one or both Units to support decay heat removal aom the RCS. This condition occurs due to afire initiated trip of the Main Feedwater Pumps or start signal to the credited MDAF'. This auto-start signal generated by this rondition opens the associated recirculation valve and motor operated discharge valve(s) polr the steam generator to be supplied AF. Due tofire damage, the motor driven Jischarge valve may fail to open and the mini-recirc valve may fail closed due to a loss of strument air supply.
"he difference in the conditions described in OD CR 01-3648 and this OD is the failure echanism of the MDAFP recirculation line, however the failure mechanism for the
- DAFPs is the same. The condition described in this OD, as it pertains to Appendix R, is jounded by that described in OD CR 01-3648 because the initiating event is essentially fhe same for both conditions, i.e., auto-start of the MDAFP and loss of control of the Imotor operated discharge valve(s) for the steam generator due to fire damage. The loss instrument air described in OD CR 01-3648 is equivalent to the recirculation line ilure mechanism described in this OD because loss of instrument air is assumedfor all 1ppendix Rfires and the failure mechanism described in this OD could appy to all fire itiated'starts of the MDAFPs. Therefore, failure of the MDAFPs as described in OD R 01-3648 is the same for this condition andAppendix R operability conclusion of 10perable But Nonconforming also remains the same.
ielated AR Number CR 01-3595 Olmpact:
.*losed. Concerns postulated failure of the recirculation line AOV. This is a related issue but it does not
,Irnpact this OPR.
felated AR Number lrmpact:
Ikeview additionally. as applicable, these items to help clarify current plant conditions.
]these items may have impact on the SSC performance.
lctive Temporary Operating Procedure Changes None Applicable P B F -
1 53 Rcvision 10116/02 Pa i.
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9207554374 POINTBEACH PAGE Sggregate Re*i ew: ldentify related issues by review of active ODs for the same system including as licable their compensatory measures. Historical ODs can also be included in this review at the discretioii rfthe Engineer. The reiew of the active ODs and their compensatory measures is to ensure there is no f.0nflfct between the related conditions, i.e. conflicting assumptions or compensatory measures
+/-+/-zi+/-
_.Uz 132U7554374 POINTBEACH PAGE 0 2
!Active Temporary Modifications None Applicable Iodifications currently being installed None Applicable Recent Work Orders None Applicable Ikpproved DCNs None Applicable Recently Performed Inservice Testing IT-10 p
4 evaluate the CLB functions and performance requirements identified in Step 2 against the as-found tondition and the related issues identified in Step 3. The evaluation must identify the extent to which the ESC is capable of performing its identified CLB function. Document the evaluation:
f4fter the automatic initiation ofAF in response to an analyzed event, operators are
- -equired to manually control AFflow based on SG levels (FSAR 7 3.3.4). Manual control (nay include shutting pump discharge valves resulting in pump operation strictly on fecirculation flow. Due to the potential debris blockage ofthe recirculation line s triction orifices (1/2R0-4003, RO-4008, RO-4015). sufficient flow topreventpump lmamage may not be achieved
- Iso, as described in CAP 030040, a loss of 120 VACpowerfrom Vital Instrument panel
"-06 can result in loss of recirculation flow due to the recirculation line valve failing losed. CAP 030209 describes a third condition where the loss of l25VDC bus D-01 tould result in the loss of IP-29, 2P-29 and P-38A due to the closure of the recirculation Ine valves.
ýIeasures taken include heightened Operator awareness of the potential for pump
- Iamage (briefings with on-coming shifi personnel), temporary information tags posted
ýn the AFW pump flow controls. Revisions to operating procedures that will alert the perator to the limitations of the AFW system with respect to minimum AFW pumpflow Ppre in progress. The revisions will ensure that AFW Minimum Flow Requirements are Ii aintained or the affected AFWpump is secured kJ.EAMIA guidelines states that motor driven pumps may be started twice from an initial
- 4. andby condition with no restrictions. After the initial starts, NEMA MG-i recommends sequent starts after "all conditions affecting operation have been thoroughly estigated and the apparatus has been examinedfor evidence of excessive heating.
is guidance encompasses situations where the load or prime mover may have experienced a fault which causes afailure to start or run; excessive temperatures are not
.xpecred with the equitment functioning normally. Additional starts therefore are Ollowed and not expected to cause machine failure. It should be recognized minimum of
$ starts of a motor driven AFpump are allowed in thefirst 15 minutes of operation. An 4dditional one or two starts is allowed provided the run time is at least 15 minutes 4etween these later starts. Motor starting nameplate information directs that after initial Iarts the motor may be restarted if run time has exceeded 15 minutes or it has been cured for 60 minutes. Excessive consecutive starting will decrease overall motor life.
$tarting duty limitations are provided by the manufacturer to provide the longest k~ossible motor life.
? e AOlP SG control band is 29% to 65% This represents an approximate volume of O0 gallons. At a steaming rate f/SO gpm, a motor driven pump atart would be ALequired every 50 minutes to control level within half ofthe control band At marimum PBF-15531 Revi*ion d110/16(02 Page 5 of 9 Pefemn.-
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,.mnpflow rate of 2 0 0 gpm. the pump would be operated for 16 n:nutes to recover the vel lost while the pump was secured Since the operation of the pumps will meet the EMA criteria established, the pump motor will not fail as a result of repetitive starts Vie pump motors are suppliedfrom Westinghouse DB-50 Air Circuit Breakers. Vendor Wiformation indicates an in-rush, non-fault ditty cycle of 750 breaker operations The Aecommended operating conditions are a frequency of operation not to exceed 20 per 10 4inutes or 30 per hour. Since the MDAFPs are only used during startup, shutdown including SG chemical additions) and required system testing, the number of breaker kperations are well below these operating limits If an operator is required to secure and
ýstart pumps during a transient, the actions would be performed at afrequency of 4peration much less than the recommended valuefor the entire transient.
r7here are no starting cycle limitations on the turbine driven AFW pumps. The turbine tendor was contacted and verified that no duty cycle concerns exist for this pump
.ssembly. The steam supply MOVs are rated for 5 minutes of operation every hour which torresponds to five open/shut cycles With a maximum steaming rate of 75 gpm, it would take approximately 33 minutes to steam off half of the control band (2500 gallons). The hameplate guidance for motors and valves is based on manufacturers" recommendations or long life and are considered conservative. Therefore, operation of the valve will not Ve degraded.
Whe recommendations of this Operability Determination is to consider the AF system QPERA BLE but NON-CONFORMING. The potential Non-Conformance pertains to the AR statement ofthe minimum recirculation flow path ensuring minimum flow is izvoilable V
ýiote: If the SSC is determined to be inoperable based on this evaluatiou, mark Step 5 N/A and continue
.iith step 6.
- 5.
Evaluate the need for compensatory measures. Complete with input from DSS.
j]
Degraded or nonconforming, however, no compensatory measures are required.
Degraded or nonconforming. The following compensatory measures are REQUIRED in order to maintain operability.
If Compensatory Measures are not required go to Step 6.
SCompensatory measures must be in place prior to OD final approval by the DSS Affecte Unit (I OR2 ORO) 0
!.Describe the Compensatory Measure (what needs to be performed) ks an immediate compensatory measure, a briefing of all responsible on-shift Reactor 4Operations staff should be conducted describing the concern and appropriate responses:
I"
- J. if discharge flow cannot be maintained per the applicable operating procedure (s) without exceeding desired SG level, secure the associated pump(s) and re-start again later when (i.9 needed POF-ISSii Rcvi-0Ort9 10116f02 Page 6 of 9 Refetence NP 53 7 zI, 1 21. / 2LJrd..'
18 :27'
':2L"7554374 POINTBEACH P..t.GE 02'
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11/21/2002 18:27 9207554374 4 Install tags. placards. or otherwise post the pertinent njbrinatton at the controls (In Sthe Control Room and locally) for the associated AFIf pumps 11 Emphasize verifying a minimum of 50 (75) gpm flow through a motor (turbine)
Sdriven pump when reducing flow as stated in the operating procedures.
,a sis which indicates the Compensatory Measure maintains operability ky verifying minimum pumpflow requirements, the continued availability of the AFW Rumps is ensured. Minimum pump flow maintains hydraulic stability, removes pump heat ind increase the life of the pump If the minimum flow requirement cannot be
- isaintained, then the pump will be secured to prevent damage. Repetitive operation of a
ijs an additional action, revise operating procedures as appropriate to prevent reducing 4orw of operating AFW pumps below the minimum flow requirements.
.nplementation Mechanism (Procedure number, Temp Mod number, etc):
is determined appropriate by Operations.
flant condition(s) or mode(s) of operation wbich require the Compensatory Measure:
1?dodes 1, 2, and 3 (modes in which decay heat removal from the SGs is necessary and required capability per MTS.
Under what conditions may the Compeasatory Measure be terminated?
ýFEngineering evaluation or modification to restore the function of the recirculation lines.
- 6.
flrpared By:
CU,;.,r
£:tsL-
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C..
,,L Date/Time:
- 160, Name (Print) / Signature
.Engineering Manager Approval of Evaluation and Proposed Compensatory Measure (if applicable)
~~- ~
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Date/Time:Y/
Name (Print) / Signature
- 7.
1SRO Review of Operabilitq Documentation:
3FJ Inoperable - does not meet the minimum level of performance.
i U]
Operable - fully meets performance requirements. No further action required.
Operable But Degraded - or Operable But Nonconforming - meets the minimum required level of performances, compensatory measures ARE required FBF-10I R~t,,sio,9 10116/02 Page 7 of 9 Ftef'rence: 1JP 5 3 7 POINTEEACH
11,21 18: IU:27 9207554374 Operable But Dcu.raded - or Operaole But Nonconforming - meets the minimum requ'red level of performances. compensator. measures are NOT required Evaluation Accepted Evaluation and Compensatory Measures Accepted Compensatory Measures Verified in Place.
NP 10 I., LCO Tracking Log updated to include new items bSS- >-/
R
-Nam (RPent)
Date/Time:
Name (Print) / Sig~nature 7_j Z _ 1 Route dD package to in-box in WCC for processing Package includes original Part I, all attachments. and related bonditzon report.
I.
POF-I5S0 Rv*iIspo9 10116/02 Refcre*ce" NP5..37 D
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