ML20065P476
| ML20065P476 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 12/31/1993 |
| From: | Karner J, Kiper K, Oregan P NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO), YANKEE ATOMIC ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20029C581 | List: |
| References | |
| 93-53, NUDOCS 9404290105 | |
| Download: ML20065P476 (33) | |
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PRA EVAL.UATION. I PROPOSED CHANGES IN ! L SERVICE WATER TECH SPEC 3.7.4 l l 1 l .f 1
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Engineering Evaluation 93- 53 December 1993 i Prepared by \1/21/43 9 : K. L Kiper j M S. L stIcohs l Ws. Ycamer aue-.a br /kW 6 bw ! i e - er 9, P. J. O'R n,YAEC l 1 m l Approved by E4 'l " '// t/fy >- v J. Vogos v i I 9404290105 940325 PDR ADOCK 05000443 P PDR
'1
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PRA EVAL.UATION: PROPOSED CHANGES IN SERVICE WATER TECH SPEC 3.7.4 Table of Contents Page 1.0 Introduetion... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..............3 2.0 Background ........ ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 3.0 Discussion .. .. ...... .......... .. ... . . . . ...............................................4.- 3.1 SW System Model ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . .5 3.2 Initiatin9 Event - Loss of One Train SW. .. . . ... . .... ....... . ....
. . . . . . . . . . . . . . . . . . . . . . . I2 .
3.3 Plant Model .. .... . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
- 4. 0 Co n cl u sion . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .............15 5.0 R eferences .. .. ..... .. . . . . .. .. . .. . . .. .. .
...............................................15 Attachment A - SW System Model Summcry ... .. . . ...... .......... ... ... .... ....... . .. ................ .... A- 1 Attochment B - SW Maintenance Doto Detoils .. ................... ..................... ....................... . ...B-1 Atto ch m ent C - SW System Results.. .. ... .. .. . . . . . .... .. .. . ...... . . . ....... .. . . .. . . .. . .... ... . . . . . . . . . C.1 Attachment D - Initiating Event Results - Loss of One Train SW .... .......... .. ................ . .. .. D-l Attochment E - PIont Model Results ...... ......................................................................E-1 ,
r 1 Page 2 ; u... - iu m i l 1
PRA EVAL.UATION: PROPOSED CHANGES IN SERVICE WATER TECH SPEC 3.7.4 1.0 Introduction This evoluotion documents the change in operational risk, at the system level (system ovoilobility) and at the plant level (core demoge frequency), for a proposed change in the Allowed Outoge Times (AOTs) for the Service Water (SW) System. This is a follow-on evoluotion from Engineering Evoluotion 92-09', based on the octual submitted 2 Tech Spec change , the most current S.obrook Station Probabilistic Sofety Study (SSPSS-1993)3 , and more detailed documentation suitable for peer review.
2.0 Background
The current Service Water Tech Spec (TS 3.7.4) applies AOTs to oil six SW pumps - four ocean water pumps and two cooling tower pumps. These pumps are each 100% capacity and provide triple redundancy per train. In addition, the Tech Spec 3.7.5, Ultimate Heat Sink, addresses the ocean SVv oumphouse and the CT basin separate from the pumps. In the licensing design basis, the cooling tower is the dsmically qualified ultimate heat sink while the ocean SW is the tornado qualified ultimate heat sink. Thus, to define operobility, one train of SW must contain one SW pump from the ocean, one Cr pump from the cooling tower basin, and the associated flow paths to the PCC and DG heat exchcngers. A new Tech Spec 3.7.4 has been proposed that:
. Combines th ,, resent TS 3.7.4 and 3.7.5. Because of the relationship between the ultimate heat sinks and the SW system, o single Tech Spec is clearer and removes ambiguities.
. Brings consistency among the vc.rious AOTs. For example, the current TS 3.7.5 allows the SW pumphouse to be unavailable for 24 hours, but TS 3.7.4 does not oddress the equivalent condition of having both ocean SW pump trains unavailable.
. Brings this Tech Spec in line with the standard Tech Specs. The stonderd Tech Spec for SW has a 72-hour AOT for o single train.
To account for the combinations of components that could be out of service, four pump loons have been defined: SWA - ocean SW pump train A (2 pumps), SWB - ocean SW pump train 8 (2 pumps), CTA
- cooling tower pump train A (one pump), and CTB - cooling tower pump train 8 (one pump).
The new proposed Tech Spec is summarized below, with a comparison of the current Tech Specs. Page 3 tit 2Mw DOC 42393 -
, , Allowed Outoge Time Components / Loops "' Current TSs Proposed TS Inoperable 3.7.4, 3.7.5 3.7.4 1 SW pump 7d N/A "'
1 SW train A pump and 1 SW 72 hr N/A train B pump SWAgSWB 24 hr 72 hr CTA g CTB 72 hr 7d CTA and CTB not explicit (*' 72 hr CT Basin 72hr 72 hr SW Pumphouse 24 hr 24 hr SWAod SWB not explicit 24 hr (SWA g SWB) and (CTA m not explicit 24 hr CTB) Table Notes:
"' SW loops (SWA, SWB, CTA, CTB) are defined above.
*' Some combinations of loops unavailable are not covered in the current Tech Spec 3.7.4.
Dese combinations are generally equivalent to conditions addressed in T,ch .cpec 3.7.5 for the ultimate heet sinks.
"' N/A = not opplicable. These conditions would not be restricted by the proposed Tech Specs.
3.0 Discussion This Tech Spec change impacts risk by increasing the likelihood that a SW pump would be unavailable due to planned or unplanned maintenance. This change is evoluoted by considering the impact on system unavailability (Section 3.1) and on the frequency of shutdown due to loss of one train of SW (Section 3.2). These impacts are combined in the plant model to produce o delto core domoge frequency (Section 3.3), in addition, o sensitivity cose is evoluoted to examine the risk importance of the standby SW pump. This case assumes the two standby SW pumps are permanently removed, so that the system consists of two ocean pumps and two CT pumps. This is not the best estimate calculation since the station is committed to maintaining the standby SW pumps but is presented to examine the bounding case. Page 4 f t9BBw 00C 112193
4 3.1 SW System Model The SW system is included in the current Seabrook PRA - SSPSS-1993 (the base case), This model . includes the ocean SW pumps, the Cooling Tower and pumps (manual actuation only), the flow path through the PCC and DG heat exchangers, and the associated oreo ventilation. Attachment A is a summary of the SW system model. This evoluotion considers only changes in maintenance unavailability due to the proposed change in Tech Specs. The following table describes how the changes from current to proposed Tech Specs have been modeled. Component / Current Prooosed Changes Comments Loop TSs TS Modeled inoperable AOT AOT ? 1 SW pump 7d N/A yes Modeled as increased unplanned (standby pump) maintenance duration and new planned maintenance contribution, for each stondby pump. 1 SWA pump 72 hr N/A no This combination is not modeled because of and 1 SWB the low frequency of entering this condition, pump i.e., having one pump foil and the stondby (stondby pumps) pump in the opposite train foil while the first one is being repaired. SWA g SWB 24 hr 72 hr yes The failure of either SW loop is assumed to (loop) cause or require o plant shutdown due to loss of RCP motor cooling. This is modeled in the loss of one train SW initiators. CTA g CTB 72hr 7d yes Modeled as increased unplanned l (loop) maintenance duration. CTA and CTB not 72 hr no While this combination is not covered (loops) explicit explicitly by the current TSs, it is equivalent to i the CT basin allowed outoge, which has not l changed. CT Basin 72 hr 72 hr no No change. ) SW Pmphouse 24 hr 24 hr no No change. SWA and SWB not 24 hr no While this combination is not covered (loops) - explicit explicitly by the current TSs, it is equivalent to the SW pumphouse allowed outage, which hos not changed. (SWAgSWB] not 24 hr no These combinations are not modeled because g.n.c! explicit of the low frequency of entering such o j (CTA gCTB] condition- ) (loops) Page5 u.a.wc imu
~
9 The maintenance contribution to the SW system model is described below (the Base Case model);: , then the model with the change in Tech Spec is presented (the "New" model). (1) Bose Case (Current) Maintenance Model 3
..This model includes contributions from unplanned maintenance, based on the number of pumps, the maintenance frequency, and the maintenance duration, os follows:
e ~ Standby ocean SW pump, for each loop,7-day LCO: , AMNTI'= BMNTI (troin A , train B)
= 2 x ZMPSWF x ZMPLSD = 0.0192 (2 SW pumps per loop) I e Standby cooling tower pump,72-br LCO:
AMNT2 = BMNT2 (troin A , train B)
= ZMPMSF x ZMPMSD = 0.00130 (1 CT pump per loop)
- Cooling tower fans, based on TS 3.7.5, 72-br LCO:
AMNT3 = ZMPMSF x ZMPMSD = 0.00130 (train A - 1 CT fan per loop) BMNT3 = 2 x ZMPMSF x ZMPMSD = 0.00260 (train B - 2 CT fans per loop) where the frequeracy and duration variables are based on generic data from PLG-0500, as follows: ZMPSWF = 3.35E-4 (meon) - Maint Freq. - operating SW pumps ZMPMSF = 1.17E-4 (meon) - Maint. Freq. - standby pumps (CT pump /fon) ZMPLSD = 28.7 hr (mean) - Maint. Duration - pumps, 7-day LCO ' ZMPMSD = 11.1 hr(meon) - Maint Duration - pump /fon,72-hr LCO These values are means of distributions developed from generic maintenance dato, taken d from PLG-0500 . Attachment B provides the generic dato that was the basis for the distributions. Maintenance assumptions in the current model: , e Molntenance frequencies and durations are based on generic industry dato and not on Seabrook specific dato due to the limited operational data. This data was collected by - ' PLG from o number of nuclear plants for similar equipment and is judged to be reasonobly representative of expected Seabrook experience. (Note that the mean Page 6 I I m m..oc unu I 1
.I
4 maintenance duration is considerably less than the AOT based on octual experience, but increases with longer AOT.)
- No planned maintenance is done on the SW system during power operation that makes a pump inoperable.
- No contribution is given to 2 SW pumps in unplanned maintenance at the some time because of the low likelihood of dual pump failure or failure of the second pump while the first was being repaired.
- No explicit maintenance contribution is modeled for volves, instrumentation, etc., that would make o loop inoperable. The pump (and CT fans) contribution is assumed to dominate maintenance unovailability,
- No contribution is given to having the SW pumphouse or the CT basin out for maintenance because of the low likelihood. During a storm in the fall of 1992, the SW suction was switched to the Cooling Tower because of the presence of large amounts of seaweed in the circulating water traveling screens. This was taken as a precaution and did not reflect the true unavailobility of the ocean SW pumphouse. (Also, the proposed Tech Spec does not change the AOT for the SW pumphouse or the CT basin.)
Maintenance contribution from failures of SW or CT ventilation is not included because it is assumed that remediol action would be taken to keep the SW system operational.
- Mointenance is unrecoverable. This assumption may be very conservative for some maintenance activities where the system con be made operable quickly.
(2) New Maintenance Model A "New" SW model was developed to account for the proposed changes in Tech Specs. These changes impact the modeling of unplanned maintenance and planned maintenance, as follows: Unplanned Mointenance:
- Standby SW pump in each loop, no LCO:
AMNTI' = BMNTI' (train A, train B)
= 2 x ZMPSWF x ZMPSWD = 0.0652 (2 SW pumps per loop)
. Standby cooling tower pump,7-day LCO:
AMNT2' = BMNT2' (troin A, train B)
= ZMPMSF x ZMPLSD = 0.00335 (one CT pump per loop)
, Page 7 mm.wcmm
- Cooling tower fans, based on TS 3.7.5, unchanged:
AMNT3 (train A - some os current model) BMNT3 (train B - some os current model) where the variables are based on generic data from PLG-0500, as follows: ZMPSWD = 97.4 hr (meon) - Maint. Duration - SW pumps, no LCO Other variables - see current model Maintenance assumptions:
. The standby SW pump is repaired in unplanned maintenance with no special priority -
consistent with other pumps with no LCO. This is believed to be conservative; a SW I pump failure woald still receive high priority. The variable ZMPSWD was develored from the dato vuriable ZMPNSD in PLG-0500, using generic data for SW ond CC pumps, judged to be more representative of the SW and CC pumps at Seabrook. (See Attachment B for details.) Planned Maintenance for the stondby SW pump in < och loop:
= PLMNTA = PLMNTB
= 2 x (1/4 yr) x (1 yr/ 8760 hr) x (336 hr) = 0.0194 (2 pumps per loop)
Assumptions:
. Each SW pump is unavoitable due to planned maintenance once very four years for 14 days (336 hrs).
- Planned maintenance is done on one pump at a time - no PLMNTA x PLMNTB terms.
The quantification for the "new" SW model is in general as follows SW Unovoil. = ( SWpumps(hordware failure + unplanned maint. + planned maint.) x CTpumps (hardware failure + unplanned maint) )
+ common components failure where the terms in bold are the ones offected by the proposed Tech Spec change.
s
- 3) Sensitivity Case The sensitivity cose assumes the standby ocean SW pumps, one in each train, are permanently unovailable. Unplanned maintenance on the operating SW pumps is assumed to require o plant trip, and thus is reflected in the initicting event, loss of one SW train. The CT maintenance is modeled the some os the "New" Tech Specs, above.
Page 8 titBMW DOC 112191 b
g'* s
- 4) Ouontitative Results - Systems Analysis- ,
The SW system configuration is quantified for a number of different boundary con'ditions. L Boundary conditions are the signals and support systems, external to the SW system, that . impact the system configuration. For example, with loss of offsite power (LOSP), the SW !
. pumps must restart, presenting a different failure mode - pump fails to stort - that is not ,
present when offsite power is available. The important boundary conditions for the SW - ; system are the number of support systems (e.g. AC power) ovoilable, LOSP, Si signal,~'ond whether the Cooling Tower is included. The combination of two-train boundary conditions - that are of interest is given below. Similar single-train configurations have also been . qaantified. System' Number LOSP SI Signal CT Comment Configuration of Trains initiator Present . Included SW1 2 x- Normal configuration, with_ CT: 4 ocean SW pumps and 2 CT pumps. SW2 2 Normal configuration, no CT: 4 ocean SW pumps. SW3 2 x Loss of offsite power, no CT: . 2 ocean SW pumps. SW4 2 x x Si olignment, with CT: 4 ocean SW pumps and 2 CT pumps. l SW5 2 Sl olignment, no CT: x 4 ocean SW pumps. [ - SW6 .2 x CT only: 2 CT pumps. ;
- Cooling Tower is included in the SW system assuming manual actuation. This action is J not credited for offsite power (LOSP) due to the short time avoilable to restore DG cooling, a and for other severe hozords (e.g., seismic events) due to the confusion that might result in I the control room.
Page 9 fffBEw DOC 12.23m3 l ll j
4 E With the rnaintenance contribution changes above, the SW system unavails .ity changes as follows: System Unovoilability Maintenance Contribution
' Percent of TOTAL)
System Configuration TOTAL: (Percent Unplanned Planned Maint. Current TS Chan9* Maint. New TS from Base , Sensitivity Case case) SW1 3.91 E-7
- 6.3 % -
z Normal configuration, wim G 3.97E-7 (1.5 %) 16.8 % 3.8 % - 4.18E-7 (6.9 %) 3.7 % - SW2 3.96E 5 4.6 % - Normos con 6gurch, tw C. 3.98E-5 (0.3 %) 14.5 % -4.0 % 4.25E-5 (7.3 %) 1.1 % - 7.64E-4 '4.5 % SW3 7 44 - Lo$$ o' o'f* Po*"- 7.64E-4 (<0.1 %) 14.1 % - 3.8 % 7.64E-4 - (<0.1 %) 1.1 % 5 4.5 % SW4 3.17E-4 q;c qi -- 5' *Geam*at *'* G- 3.17E-4 (<0.1 %) 14.2 % 3.8 % ' 3.17E-4 (<0.1 %) 1.1 % - - SW5 3.58E-4 'M 4.5 % - sawwsms , si augnm.nt no a. 3.59E-4 (0.3 %) 14.2 % .3.9 % 3.63E-4 (1.4 %) - 1.1 % . SW6 9.89E-3 , 6.2 % - - 1 a alon*- 1.00E-2 (1.1 %) 16.5 % 3.8 % 1.00E-2 (1.1 %) 3.9 % - ! l i Page 10 titSRw Dct 112M3 l
l See Attachment C for details of the maintenance quantification. These results, both for the current and the new TS, are based on point estimate i quantifications of the system. The current SW system analysis in the SSPSS-1993 is quantified using Monte Carlo uncertainty methods. However, in compor:ng the small changes in system quantification that the change in Tech Specs produces, the effects of the 1 Monte Carlo uncertainty overwhelm the results. Thus, to isolate the impact of the Tech l Spec change alone, the system quantification for SW is presented using point estimate. 1 The results at the system level indicate that the change in system unovailability is extremely small for all cases, with a maximum change of less than 2%. This change is insignificant in comparison to the uncertainty of the results. The change in system unavailability is small even though tne relative importance of maintenance increased from ~5% to ~15% of the l system toto!. This is due to the multiple redundancy in the system and also the way it is ! modeled, as follows: ! SW1 - Normal configuration: 4 ocean SW pumps and 2 CT pumps. Because of the high level of pump redundoney and the modeling of common mode failure, the standby , pump tends to contribute little to the overall system ovoilobility. Also, the less ;edundant l ventilation system, which dominates this configuration, is not offected by maintenance. Thus, when maintenance is increased, it has little impact. SW2 - Normal configuration without the CT: 4 ocean SW pumps. Because of the l redundancy with the ocean SW pumps, the standby pumps tend to contribute little to ! the overoll system ovoilobility. Because CT is not included in this configuration, Tech ! Spec changes offecting the CT do not impact SW2. ; i SW3 - LOSP configuration: 2 ocean SW pumps. The operating SW pumps will automatically load onto the diesel generators. The standby SW pumps and CT pumps i do not auto-start on loss of the operating pumps. Because of the need for SW cooling 1 of the diesel generators, no credit is given for manual actions to stort the stendby pumps. Thus, the standby pumps which are impacted by the Tech Spec change are not included in SW3. 7 i
. SW4 - 51 configuration: 4 ocean SW pumps and 2 CT pumps. This is similar to the l normal configuration (SWl) except the isolation of non-essential loads is also required. '
Common cause failure of the isolation MOVs to close is the dominant failure cutset.'- This cutset is not impacted by the Tech Spec changes. ! l
. SW5 - 51 configuration without the CT: 4 ocean SW pumps. This has the some basis as '
SW4 for the minimal impact of maintenance.
. SW6 - Cooling tower only: 2 CT pumps. This is impacted only by the change in CT pump AOTs. Because of common cause failure modeled between these pumps and the operator action to initiate CT, the increased maintenance contribution is not significant.
Page 11 If9BNw DOC 1MM1
Lus, the impact of the Tech Spec change on SW system unavailability is insignificant, and it could be concluded that the impact on the plant model (i.e., core domoge frequency) would be negligible. These changes are included in the plant model evoluotion in Section 3.3. The sensitivity case resulted in a maximum change of about 7 %, for the system configurations where all 4 ocean SW pumps are modeled in the base case. This change is also insignificant in light of the ossociated uncertainty. 3.2 Initiating Event - Loss of One Train SW Loss of either train of SW would offect the plant power generation through PCC cooling to the RCP motors (SW cools PCC heat exchangers). This impact is modeled as two initiators, LISWA and LISWB. The frequency of loss of one SW train is given by the frequency of loss of one ocean SW pump over one year of operation and failure of the other ocean SW pump while the first is being repaired. This also includes failure of the operating pump while the standby pump is out for maintenance - either planned or unplanned. Here are also other combinations of volves, heat exchangers, etc. that could fail and contribute to loss of the train; however, they are not offected by this Tech Spec change. In addition, no credit is given for operator action to stort the Cooling Tower in time to prevent the shutdown. -l The simplified equation for loss of one SW train con be written as follows: LISW = (FR(PmpA)*T(yr)) * [FS(PmpC) + FR(PmpC)*T(repair)) + [FR(PmpA)*T(yr)
- MNT(PmpC)] +
[FF(Common Volves)) , where: FR(Pmp)= failure rate for operating SW pump to continue to run
= 9.95E-6 / hr (SISWPR)
FS(Pmp)= failure rote for standby SW pump to stort
= 1.61E-3 / demand (SIPMOS)
T(yr) = duration the operating SW pump must run
= 8760 hr per yr
- 0.70, plant availability factor, T(repair)= duration of unplanned maintenance on failed pump A, MNT(Pmp)= pump unovailability due to planned and unplanned maintenance, FF(Common Volves) = failure frequency of common volves transferring open or closed over the operating year = 1.65E-3 (see Table D.1).
Page 12 18955w DOC t2.1393
=
l- , t .+
~
- The two terms T(repair) and MNT(Pmp) are the ones that change due to the new Tech Spec AOT, .
os follows: Current TS Model - <
- New TS Model y -7_ 1 T(repair) ZMPLSD = 28.7 hr ZMPSWD = 97.4 hr I
MM'mp) /
= N + UM , ,' . et . p ,. , . g. ,
f PM none 2*(1/4)*(1/8760)*336 = Planned Maint. ' O.0192 UM ZMPSWF*ZMPLSD = ZMPSWF*ZMPSWD = Unplanned Maint. 0.0096 0.0326 where the variobles are defined earlier. Le results from the RISKMAN system initiator model are given below. Similar results con be calculated with the simplified model above. LISW Initiator Frequency N#Y D Maintenance Contribution
, ,,.g (Percent of TOTAL)
"" ~
TOTAL (Percent Change Unplanned Planned
~
frorn Base Case) g
} Maint. Maint.
Current TS Model 2.63E-3 per yr gagdN[$$$$$ J 22.3 % - - (w/ point est. calc) !#1Mg fjj@pgg i New TS Model 5.252-3 per yr (100 %) 38.9 % 22.7 % Sensitivity Case 6.33E-2 per yr - (1400 %) - . i l As explained in Section 3.1, these results were obtained using point estimate quantification, rather - I than Monte Carlo uncertainty calculations. This allows the change due strictly to change in the ? Tech Spec to be isolated. The detailed results for loss of one train of SW ore given in Attachment I D. I Page 13 m.m = iam .I
.)
e ^ Aus, the initiator frequency increases by about a factor of 2. This large increase is due to the
- significance of maintenance in the current model.
For the sensitivity cose, the increase is about a factor of 25. This impact is more dramatic, since the assumption is that failure of either operating SW pump would force a plant shutdown; no credit is given for manually starting the CT and remaining at power. 3.3 Plant Model ; Service Water has two general safety functions, cooling PCC and cooling DGs. Thus, failure of SW ' effects the plant model in those two ways:
. For transients and LOCAs, loss of SW fails PCC which results in loss of cooling to RCP sects :
and to ECCS pumps, and
. For loss of offsite power, loss of SW fails the DGs (assumed unrecoverable) which results in station blockout.
Attachment E, Table E.1 contains the dominant CD sequences (top 25) for the base cose, with the sequences that do not involve direct failure of SW shaded. From this table, it con be seen that the , dominant SW sequence is LOSP with failure of both tro!ns of SW and no recovery of offsite power. De next intemot event sequences failing SW ore loss of one train of SW initiating a plant shutdown followed by failure of the CT and the opposite train SW and CT. The next sequences involve transients (e.g. RT) with failure of both trains of SW. , , Table E.2 presents the top 25 CD sequences with the new SW Tech Spec modeled. By comparing the dominant sequences, the most important change is clearly the change in initiating event frequency for loss of one train of SW. he plant model results are os follows: , Plant Model Results Core Domoge ~ Percent Frequency . Change from (per year) Bose Case SSPSS-1993 CDF (Monte Carlo) 8.02E.5 fin 1@s 4Bose Case CDF (with SW point estimate) 8.06E.5 . (sMnW
$New SW Tech Spec 8.25E-5 2.4 %
Sensitivity Case 1.18E-4 46.4 % , his change is dominated by the initiating event frequency for loss of one train of SW. . Page 14 i stenaw cae Inses -
' l e
J l The total CDF change due to changes in the SW Tech Spec is about 1.9E-6 per year, or 2.4 %, compared to the ronge of the CDF distribution which is opproximately one order of magnitude I (from 5th to 95th percentile). Thus, this is on insignificant change within the uncertainty bounds on the CDF distribution. l The change in CDF in the sensitivity cose is more significant because of the importance of the loss of one SW train initiator. This change is still within the upper bound CDF estimate. Using this sensitivity cose, the Risk Achievement (RA) importance factor for this change con be calculated: RA = 1.18E-4 / 8.06E-5 = 1.46 4.0 Conclusion As a result of the quantitative evoluotion above, the effect of the changes proposed for TS 3.7.4 is generally small for the SW system unavailability and is significant for the SW initiating event frequency. However, with these changes in the plant model, the overall result is insignificant to the core demoge frequency. This evoluotion is based on a best estimate of planned and unplanned SW pump maintenance. The evoluotion does rot include the positive contributions due to removing the major SW pump maintenance activities from outages. These contributions include reducing the unavailability of SW pumps during outages and permitting more flexibilityin outage planning. The outage effects are very sensitive to the configuratic,n of the primary system, time ofter shutdown, other systems unavoilable, etc. and thus are difficult to estimate. As a result, the proposed Tech Spec change does not increase the core demoge risk within the bounds of the uncertainty. 5.0 References
- 1. North Atlantic Energy Service Corp., "PRA Evoluotion: Change in Service Water Tech Spec 3.7.4," Engineering Evoluotion 92-09, Rev. 2, Dec.1992.
- 2. NAESCo letter, T. Feigenbaum to USNRC, " License Amendment Request 93-02:' Service Water System / Ultimate Heat Sink OPERABILITY Requirement' (TAC No. M85750)," April 7,1993.
- 3. North Atlantic Energy Service Corp., "Seabrook Station Probabilistic Safety Study - 1993 Update, (SSPSS-1993)," July 1993.
- 4. Pickard, Lowe and Garrick, Inc, "Doto Bose for Probabilistic Risk Assessment of Light Water Nuclear Power Plants - Maintenance Dato," PLG-0500, Volume 3, Revision 1, August 1989.
Page 15 f fG35* DOC 111391
A 4 Attachment A - SW System Model Summary This section contains a copy of the SSPSS-1993 Tier I system documentation for Service Water. This is intended to give a summary description of the system, how it is modeled, and the base cose results (Monte Carlo calculations). Ett25w 00C E2394
7 , 3 - SEABROOK STATION.PROBABluSTic SAFET( STUDY - 1993 UPDATEL 5 1 t DOCUMENTATION NOTEBOOK SECTION 3.4- y SERVICE WATER 1l l 1 i
- I y
i i N 00'1113 : F w qe _ y -. - - _
SUMMARY
- SERVICE WATER SYSTEM 1.0 SYSTEM DEscmPT10N Function The Service Water System (SWS) provides cooling water to transfer the heat from primary (safety-related) and secondary (nonsafety related) loads to the ultimate best sink, either the Atlantic Ocean or the atmosphere. During a loss of off-site power, the SWS also provides cooling to the diesel generator jacket water coolers.
Confiouration - The SWS (see Figure 3.41) consists of a normally operating, seawater service water system, a cooling tower system, and their associated ventilation systems (see Figures 3.4-2 and 3). The seawater service water system includes two independent and redundant trains which take suction from a common bay in the service _wster pumphouse. Each train contains two parallel service water pumps, one normally operating and the other in standby. The Cooling Tower System also includes two independent trains,' with one cooling tower pump per train. Fans are provided to remove heat from the cooling tower. Dependencies - Support for the normal SWS is provided by the Service Water Pumphouse Hosting and Ventilation System and by the Electric Power System. Support for the Cooling Tower System is provided by its associated Hosting and Ventilation System and by the Electric Power System. Operation - The SWS is operable during all modes of operation with one pump per
~
train in standby mode. If the operating service water pump trips, tho' standby pump automatically starts. If the discharge pressure in a service water train falls below its low-low pressure setpoint, a train associated tower actuation (TA) signal in - generated which starts the associated cooling tower pump and stops that train's service water pumps. Given a TA signal, an S signal, or a loss of off site power, the ' secondary host loads are isolated to conserve cooling water to safeguards equipment. I Potential for Event initiation v Loss of service water is a potential initiating event i because the system is required to supply cooling water to the plant PCC system Lj and SCC system host exchangers at all times during operation. Loss of either train' of the SWS would affect the plant power generation through PCC cooling to the ~
- RCPs.
2.0 SYSTEM Moost The SWS analysis includes several system models: ~ Stenok 3.4 Senvice WATen SSPSS 1993 I secoumemoci l - i
l
SUMMARY
- SERVICE WATER SYSTEM PAGE 2
. Availability of " normal
- service water, i.e., using the service water pumphouse,
. Availability of cooling towers, assumed to start only on manual actuation, and . Initiating event loss of one train of service water Top Event Definition - The SWS System is analyzed for Top Event WA (loss of SWS Train A) and Top Event WB (loss of SWS Train B)in the support systems event tree under three boundary conditions:
Case 1 - Si signal with off site power available Case 2 - No Si signal and off-site power available (i.e., general transient) Case 3 - Loss of off site power For all three cases, the SWS must continue to supply service water to the PCC heat loads after an initiating event occurs. Case 2 is applied to initiating events which require isolation of the nonsafety related heat loads (i.e., secondary component cooling). Case 3 is applied to initiating events which also require isolation of the secondary heat loads. In addition, for Case 3, the SWS pumps must restart and operate throughout the mission time. The mission time for all three cases is 24 hours. Success Criteria - System success criteria is one of two trains continuing to operate for 24 hours after event initiation. The model also assumes loss of pumphouse switchgear ventilation and cooling tower ventilation systems result in f ailure of SW and CT pumps, respectively. Loss of pumphouse ventilation is assumed to have no effect for the 24-hour mission time. The model assumes that isolation of the secondary heat loads is reouired for a loss of off site power concurrent with an S signal or for a TA signal. For small LOCA, steam generator tube rupture, and steam line break outside containment initiating events with off site power available,it is assumed that isolation of secondary heat loads is not required. Thus, for these three initiators, Service Water is quantified for Case 2 (no Si signal with off site power available). Analysis Conditions
. Operator actions to initiate cooling tower operation are modeled. No credit has been taken for the automatic generation of a TA signal.
. Failure of the operators to close the spray bypass MOVs SW-V139 an:1 SEctoN 3.4 service WATER SSPSS 1993 ,
ie m sooci
-- <r = 1
SUMMARY
- SERVICE WATER SYSTEM PAGE 3 .
SW V140 is assumed to have no effect on system performance for the mission time. Closure of these valves controls cooling tower water temperature by redirecting all cooling tower return flow to the spray headers (instead of the tower basin).
. The SWS is analyzed for various combinations of support states, including loss of off site power, S signal, TA signal, and single AC power train availability. . No credit is given for manually initiating the cooling tower for LOSP-initiated sequences because of the time dependence between diesel cooling and recovery from SW failure.
3.0 RESULTS The SW System quantification results are shown in Table 3.4-1. The definition of cutset basic events is given in Table 3.4-2. 4.0 UPDATE HISTORY The system analysis has evolved in the model updates as follows:
. SSPSA(1983) - The original system analysis. . SSPSS-1986 - Several changes were made:
The Tech Spec AOTs and test frequencies for SW pumps were changed. Recovery of SW by manually starting the Cooling Towers or isolating non-essential loads was integrated into the systems analysis in order to' correctly credit recovery. Common cause modeling was expanded to include groups of more than two components, including a SW pump group and a CT valve group.
. SSPSS 1989 - No significant changes.
. SSPSS-1990 - Several changes were made:
The recovery action to manually isolate the non-essential loads was removed from the model, since there is no explicit procedural instructions, instead, a more realistic success criteria was used so that isolation is required only for coincident LOSP and LOCA. SW pumphouse ventilation was removed from the model based on engineering judgment. SSPSS 1993 SECTloN 3.4 service WATER (CCOUPeeboCl
x
SUMMARY
- SERVICE WATER SYSTEM PAGE 4 A detailed f ault tree was developed using RISKM AN Release 2.0.
. SSPSS 1993 .Several changes were made:
The fault tree was revised using RISKMAN Release 4.0. Plant specific data was used for pump start and run and for maintenance unavailability. 8 P SECTION 3.4 SERVict WATrn SSPSS 1993 icoounamoci
SUMMARY
- SERVICE WATER SYSTEM PAGE 5 Table 3.4-1(a) Service Water Quantitative Results Two Train Service Water System (with Cooling Tower): SW1 = 3.3117E 07 No. Cutset Basic Events (a) Value Percent Cumulatve Alignment importnce importnce 1 OPTA * (FN.SWFN40A.FS, FN.SWFN408.FS) 2.124E-07 64.1362 64.1362 NORMAL 2 (FN.SWFN40A.FS, FN.SWFN40B.FS)
- 1.530E-08 4.6200 68.7562 NORMAL.
(MO.SWV4.FO, MO.SWV5.FO) 3 MO.SWV44 CL
- OPTA 1.379E-08 4.1640 72.9202' NORMAL 4 OFTA
- FN.SWFN40A.FR, FN.SWFN408.FR] 1.095 E-08 3.3065 76.2266 NORMAL' 5 [FN.SWFN40A.FS, FN.SWFN408.FS)
- 5.911E 09 1.7649 78.0115 NORMAL
'PP.SWP110A.FS, PP.SWP1108.FS1 6 (FN.SWFN40A.FS, FN.SWFN40B.FS)
- 4.531E 09 1,3682 79.3797 NORMAL IMO.SWV25.FC, MO.SWV34.FC) 7 (FN.SWFN40A.FS, FN.SWFN408.FS)
- 4.531E 09 1.3682 80.7479- NORMAL (MO.SWV25.FC, MO.SWV54.FC]
8 (FN.SWFN40A.FS, FN.SWFN40B.FS)
- 4.531 E-09 1.3682 82.1161 . NORMAL
[MO.SWV19.FO, MO.SWV20.FO] 9 (FN.SWFN40A.FS, FN.SWFN40B.FS]
- 4.531 E-09 1.3682- 83.4842 NORMAL (MO.SWV19.FO, MO.SWV56.FO) 10 (FN.SWFN40A.FS, FN.SWFN408.FS)
- 4.531 E-09 1.3682 84.8524 NORMAL (MO.SWV20.FO, MO.SWV27.FO) 11 (FN.SWFN40A.FS, FN.SWFN40B.FS)
- 4.531E 09 1.3682- 86.2206 NORMAL-(MO.SWV56.FO, MO.SWV27.FO) 12 [FN.SWFN40A.FS, FN.SWFN408.FS]
- 4.531 E-09 1.3682 87.5888 NORMAL (MO.SWV23.FC, MO.SWV34.FC!
12 (F:1.SWFN40A.FS, FN.SWFN408.FS)
- 4.531 E-09 1.3682 88.9570 NORMAL (MO.SWV23.FC, MO.SWV54.FC) e e
SSPSS 1993 SECTION 3.4 SERVICE WATER . IC00LWo.00Cl
SUMMARY
- SERVICE WATER SYSTEM PAGE 6 4
Table 3.41(b) Service Water Quantitative Results Two Train Service Water System (given LOSP): SW3 = 7.2257E-04 No. Cutset Basic Events Value Percent Cumulatve Alignment importnce importnce 1 [MO.5WV2.FC, MO.SWV29.FC] 2.505 E-04 34.6682 34.6682 NORMAL 2 [MO.SWV4.FO, MO.SWV5.FO] 2.505E-04 34.6682 69.3363 NORMAL 3 [FN.SWFN40A.FS, FN.SWFN40B.FS) 2.706E-05 3.7450 73.0813 NORMAL 4 [MO.SWV2.FCI * [MO.SWV5.FO] 2.512E 05 3.4765 76.5578 NORMAL 5 [MO.SWV29.FC) * [MO.SWV4.FO) 2.512E-05 3.4765 80.0343 NORMAL 6 [MO.SWV2.FC) * [MO.SWV29.FC] 2.512E-05 3.4765 83.5108 NORMAL 7 [MO.SWV4.FO] * [MO.SWV5.FO] 2.512E-05 3.4765 86.9873 NORMAL 8 [PP.SWP41 A.FS, PP.SWP418.FS] 1.209E-05 1.6732 88.6605 NORMAL 9 [PP.SWP418.FS) * [MO.SWV4.FO) 6.006E-06 .8312 89.4917 NORMAL i l 1 l i 4 SECTION 3.4 SERVICE WATER SSPSS-1993 ; lC00VNODOCl l
SUMMARY
- SERVICE WATER SYSTEM .PAGE 7 ..
Table 3.4-1(c) Service Water Quantitative Results Single Train (A) Service Water System (w/ Cooling Twr): WA 1 = S.1968E 05 No. Cutset Basic Events Value Percent Cumulatvo Alignment , importnce importnce 1 OPTA * [FN.SWFN40A.FS) 2.781 E-06 5.3514 5.3514 NORMAL 2 MO.SWV20.CL 2.087E-06 4.0159 9.3673 NORMAL 3 [FN.SWFN40A.FS) * [MO.SWV4.FO) 1.797E-06 3.4579 12.8252 ' NORMAL 4 [FN.SWFN40A.FS) * [MO.SWV34.FC) 1.797E 06 3.4579 16.2831 NORMAL 5- [FN.SWFN40A.FS) * [MO.SWV20.FO) 1.797E-06 3.4579 19.7411 NORMAL 6 [FN.SWFN40A.FS) * (MO.SWV56.FO) 1.797E 06 3.4579 23.1990 NORMAL 7 [FN.SWFN40A.FS) * [MO.SWV54.FC) 1.797E-06 3.4579 26.6569 NORMAL 8 OPTA
- DP.DP60A.FC 1.780E-06 3.4252- 30.0821 NORMAL i 9 OPTA
- DP.SWDP932A.FC 1.780E-06 3.42b2 33.5073 NORMAL -
10 OPTA * [FN.SWFN40A.FR1 1.353E-06 2.6035 36.1108 NORMAL 11 DP.DP60A.FC * [MO.SWV20.FO) 1.035E-06 1.9916 38.1024 NORMAL - 12 DP.SWDP932A.FC ' [MO.SWV20.FO) 1.035E-06 1.9916 40.0940 WORMAL 13 DP.SWDP932A.FC * [MO.SWV56.FO) 1.035E-06 1.9916 42.0856 NORMAL-14 DP.SWDP932A.FC * [MO.SWV34.FC) 1.035E-06 1.9916 44.0773 NORMAL 15 DP.SWDP932A.FC * [MO.SWV54.FC) 1.035E-06 '1.9916 46.0689 NORMAL 16 DP.SWDP932A.FC * [MO.SWV4.FO) 1.035E 06 1.9916 48.0605 NORMAL 17 DP.DP60A,FC * [MO.SWV54.FC) 1.035E 06 ~ 1.9916 50.0521 NORM AL - 18 DP.DP60A.FC * [MO.SWV56.FO) 1.035E-06 1.9916 52.0437 NORMAL ~ 19 DP.DPSOA.FC * [MO.SWV34 FC) 1.035E-06 1.9916 54.0353 NORM AL - 20 DP.DP60A.FC * [MO.SWV4.FO) 1.035 E-06 1.9916 56.0270 NORMAL 21 [FN.SWFN40A.FS) * [FN.SWFN51 A.FS) 9.823E-07 '1.8902 57.9172 NORMAL 22 VL.SWV68.CL 8.762E-07 1.6860 '59.6032 NORMAL 23 VL.SWV70.CL 8.762E 07 1.6860 61.2892 NORMAL 24 [FN.SWFN40A.FS) * [PP.SWP110A.FS) 8.446E-07 1.6252 62.9145 NORMAL 25 [FN.SWFN40A.FR) * [MO.SWV20.FO) 7.627E-07 1.4676' 64.3821 NORMAL , I l l SECT ON 3.4 SERVICE WATFR SSPSS 1993 .C00uhe. DOC'
.I
SUMMARY
- SERVICE WATER SYSTEM .PAGE 8 l
l 1 Table 3.4. 'M Service Water Quantitative Results 1 Single Train (A) Service Water System (given LOSP): WA3 = 1.1116E 02 l No. Cutset Basic Events Value Percent Cumulatve Alignment - Importnce importnce ' 1 [MO.SWV2.FCl 3.549E-03 31.9269 31.9269 NORMAL l 2 (MO.SWV4.FO] 3.549E-03 31.9269 63.8538 NORMAL 3 [PP.SWP41 A.FS1 1.609E-03 '14.4746 78.3284 NORMAL 4 [FN.SWFN40A.FS] 4.181 E-04 3.7612 82.0896 NORMAL 5 [MO.SWV2.FC, MO.SWV29.FCI 2.744E-04 2.4685 84.5581 NORMAL 6 [MO.SWV4.FO, MO.SWV5.FOl 2.744E-04 2.4685. 87,0266 NORMAL 7 DP.DP60A.FC 2.519E-04 2.2661 89.2927 NORMAL P SEcDON 3.4 SERVICE WATER SSPSS 1993 (C00UNQ.DOCl , i
SUMMARY
- SERVICE VtfATER SYSTEM PAGE 9 Table 3.4 2 Service Water Basic Event Definitions Basic Event Description CV.SWV1.CL P.41 A DISCHARGE CHECK VALVE SW.V1 TRANSFERS CLOSED CV.SWV1.FC P.41 A DISCHARGE CHECK VALVE SW.V1 EAILS TO RE.OPEN CV.SWV24.CL P.1108 DISCHARGE CHECK VALVE SW.V24 TRANSFERS CLOSED CV.SWV24.FC P.110B DISCHARGE CHECK VALVE SW.V24 FAILS TO OPEN CV.SWV28.CL P.41B DISCHARGE CHECK VALVE SW.V28 TRANSFERS CLOSED CV.SWV28.FC P.41B DISCHARGE CHECK VALVE SW.V28 FAILS TO RE.OPEN CV.SWV3.CL P.41C DISCHARGE CHECK VALVE SW.V3 TRANSFERS CLOSED CV.SWV3 FC P.41C DISCHARGE CHECK VALVE SW.V3 FAILS TO OPEN CV.SWV30.CL P.41D DISCHARGE CHECK VALVE SW.V30 TRANSFERS CLOSED CV.SWV30.FC P.41D DISCHARGE CHECK VALVE SW.V30 FAILS TO OPEN CV.SWV53.CL P.110A DISCHARGE CHECK VALVE SW.V53 TRANSFERS CLOSED CV.SWV53.FC P.110A DISCHARGE CHECK VALVE SW.V53 FAILS TO OPEN DP.DP191.lO FIRE DAMPER DP.191 INADVERTENT ACTUATION
~
DP.DP192.lO FIRE DAMPER DP.192 INADVERTENT ACTUATION DP.DP369.CL TORNADO CHECK DAMPER DP.369 TRANSFERS CLOSED DP.DP370.CL TORNADO CHECK DAMPER DP.370 TRANSFERS CLOSED DP.DP60A.CL SW SWGR RM RELIEF DAMPER DP.60A TRANSFERS CLOSED DP.DP60A.FC SW SWGR RM RELIEF DAMPER DP.60A FAILS TO OPEN DP.DP608.CL SW SWGR RM REllEF DAMPER DP.60B TRANSFERS CLOSED DP.DP60B.FC SW SWGR RM RELIEF DAMPER DP.60B FAILS TO OPEN DP.SWDP189.lO FIRE DAMPER DP.189 INADVERTENT ACTUATION DP.SWDP190.lO FIRE DAMPER DP.190 INADVERTENT ACTUATION DP.SWDP64A.CL RELIEF DAMPER DP.64A TRANSFERS CLOSED DP.SWDP64A.FC RELIEF DAMPER DP.64A FAILS TO OPEN DP.SWDP64B.CL RELIEF DAMPER DP.648 TRANSFERS CLOSED DP.SWDP648.FC RELIEF DAMPER DP.64B FAILS TO OPEN DP.SWDP65.CL CT SWGR RM FAN DAMPER DP.65 TRANSFERS CLOSED DP.SWDP65.FC CT SWGR RM FAN DAMPER DP.65 FAILS TO TRANSFER OPEN DP.SWDP66.CL CT SWGR RM FAN DAMPER DP.66 TRANSFERS CLOSED DP.SWDP66.FC CT SWGR RM FAN DAMPER DP.66 FAILS TO TRANSFER OPEN DP.SWDP67.CL CT PUMP ROOM EXHAUST FAN DAMPER DP.67 TRANSFERS OPEN DP.SWDP67.FC CT PUMP ROOM EXHAUST FAN DAMPER DP.67 FAILS TO OPEN DP.SWDP68.CL CT PUMP ROOM EXHAUST FAN DAMPER DP.68 TRANSFERS OPEN DP.SWDP68.FC CT PUMP ROOM EXHAUST FAN DAMPER DP.68 FAILS TO OPEN SSPSS-190'; SECTION 3.4 SERVICE WATER ICOOUNO.DOCl
l 1
SUMMARY
- SERVICE WATER SYSTEM PAGE 10 i
Table 3.4 2 Service Water Basic Event Definitions (Continued) i Basic Event Description DP.SWDP932A.CL DISCHARGE DAMPER DP.932A TRANSFERS CLOSED DP.SWDP932A.FC DISCHARGE DAMPER DP.932A FAILS TO OPEN DP.SWDP9328.CL DISCHARGE DAMPER DP.932B TRANSFERS CLOSED DP.SWDP9328.FC DISCHARGE DAMPER OP.9328 FAILS TO OPEN DP.SWDR367.CL TORNADO CHECK DAMPER DR.367 TRANSFERS CLOSED Fl.SWF192.PL CT PUMP ROOM INTAKE FILTER F.192 PLUGGED Fl.SWF57.PL FILTER F.57 PLUGGED Fl.SWF58.PL FILTER F.58 PLUGGED FN.2SWFN51 B.FR CT FAN 2.FN.51B FAILS TO RUN FN.2SWFN518.FS CT FAN 2.FN.51B FAILS TO START FN.SWFN40A.FR SW SWGR VENT SUPPLY FAN FN.40A FAILS TO RUN FN.SWFN40A.FS SW SWGR VENT SUPPLY FAN FN.40A FAILS TO START FN.SWFN408.FR SW SWGR VENT SUPPLY FAN FN.40B FAILS TO RUN FN.SWFN408.FS SW SWGR VENT SUPPLY FAN FN.408 FAILS TO START FN.SWFN51 A.FR CT FAN FN.51 A FAILS TO RUN FN.SWFN51 A.FS CT FAN FN.51 A FAILS TO START FN.SWFN518.FR CT FAN FN.51B FAILS TO RUN FN.SWFN518.FS CT FAN FN.518 FAILS TO START FN.SWFN63.FR CT SWGR ROOM SUPPLY FAN FN.63 FAILS TO RUN FN.SWFN63.FS CT SWGR ROOM SUPPLY FAN FN.63 FAILS TO START FN.SWFN64.FR CT SWGR ROOM SUPPLY FAN FN.64 FAILS TO RUN FN.SWFN64.FS CT SWGR ROOM SUPPLY FAN FN.64 FAILS TO START FN.SWFN70.FR CT-ROOF EXHAUST FAN FN.70 FAILS TO RUN FN.SWFN70.FS CT ROOF EXHAUST FAN FN.70 FAILS TO START FN.SWFN71.FR CT ROOF EXHAUST FAN FN 71 FAILS TO RUN FN.SWFN71.FS CT ROOF EXHAUST FAN FN.71 FAILS TO START LV.SWL26.PL CT PUMP ROOM INTAKE LOUVRE L.26 PLUGGED LV.SWL27.PL EXHAUST LOUVRE L.27 PLUGGED LV.SWL28.PL EXH. MIST LOUVRE L.28 PLUGGED MO.SWV19.CL SW RET'lRN MOV SW.V19 TRANSFERS CLOSED MO.SWV19.FO SW RETURN MOV SW.V19 FAILS TO CLOSE MO.SWV20.CL SW RETURN MOV SW.V20 TRANSFERS CLOSED SECTION 3.4 SERVICE WATER SSPSS 1993 IC00um3.DCCI
4
SUMMARY
- SERVCE WATER SYSTEM PAGE 11 ,
Table 3.4-2 Service Water Basic Event Definitions (Continued) Basic Event Description MO.SWV20.FO SW RETURN MOV SW.V20 FAILS TO CLOSE MO.SWV2.CL P.41 A DISCHARGE MOV SW.V2 TRANSFERS CLOSED MO.SWV2.FC P.41 A DISCHARGE MOV SW.V2 FAILS TO RE.OPEN MO.SWV29.CL P.41B DISCHARGE MOV SW.V29 TRANSFERS CLOSED MO.SWV29.FC P.41B DISCHARGE MOV SW.V29 FAILS TO RE.OPEN MO.SWV22.CL P.41C DISCHARGE MOV SW.V22 TRANSFERS CLOSED MO.SWV22.FC P.41C DISCHARGE MOV SW.V22 FAILS TO OPEN MO.SWV31.CL P.410 DISCHARGE MOV SW.V31 TRANSFERS CLOSED MO.SWV31.FC P.41D DISCHARGE MOV SW.V31 FAILS TO OPEN MO.SWV23.CL CT RETURN MOV SW.V23 TRANSFERS CLOSED MO.SWV23.FC CT RETURN MOV SW.V23 FAILS TO OPEN MO.SWV34 CL CT RETURN MOV SW.V34 TRANSFERS CLOSEO MO.SWV34.FC CT RETURN MOV SW.V34 FAILS TO OPEN MO.SWV25.CL P.110B DISCHARGE MOV SW.V25 TRANSFERS CLOSED MO.SWV25.FC P.110B DISCHARGE MOV SW.V25 FAILS TO OPEN MO.SWV54.CL P.110A DISCHARGE MOV SW.V54 TRANSFERS CLOSED MO.SWV54.FC P.110A DISCHARGE MOV SW.V54 FAILS TO OPEN MO.SWV26.OP P.110B BYPASS MOV SW.V26 TRANSFERS OPEN MO.SWV27.FO P.110B TEST RECIRC MOV SW.V27 FAILS TO CLOSF MO.SWV27 OP P.110B TEST RECIRC MOV SW.V27 TRANSFERS OPEN. MO.SWV55.OP P.110A BYPASS MOV SW.V55 TRANSFERS OPEN MO.SWV56.FO P.110A TEST RECIRC MOV SW.V56 FAILS TO CLOSE MO.SWV56.OP P.110A TEST RECIRC MOV SW.V56 TRANSFERS OPEN MO.SWV4.FO TRAIN A SCC ISOLATION MOV SW.V4 FAILS TO CLOSE MO.SWV5.FO TRAIN B SCC ISOLATION MOV SW.V5 FAILS TO CLOSE MO.SWV44.CL UNIT 1 INTAKE TUNNEL MOV SW.V44 TRANSFERS CLOSED MO.SWV74.OP SCC ISOLATION TO CT MOV SW.V74 TRANSFERS OPEN MO.SWV76.OP SCC ISOLATION TO CT MOV SW.V76 TRANSFERS OPEN OPTA OPERATOR FAILS TO INITIATE COOLING TOWER OPERATION PP.SWP110A.FR CT PUMP P.110A FAILS TO RUN PP.SWP110A.FS CT PUMP P.110A FAILS TO START PP.SWP110B.FR CT PUMP P.110B FAILS TO RUN SECTION 3.4 SERVICE WATER SSPSS-1993 (C00VNGDOCl
. *\
SUMMARY
- SERVICE WATER SYSTEM PAGE 12 Table 3.4 2 Service Water Basic Event Definitions (Continued)
Basic Event Description PP.SWP110B.FS CT PUMP P.1108 FAILS TO START PP.SWP41 A.FR SW PUMP P.41 A FAILS TO RUN PP.SWP41 A.FS SW PUMP P 41 A FAILS TO START PP.SWP418.FR SW PUMP P.41B FAILS TO RUN PP.SWP418.FS SW PUMP P.41B FAILS TO START PP.SWP41 C.FR SW PUMP P.41C FAILS TO RUN PP.SWP41 C.FS SW PUMP P.41C FAILS TO START PP.SWP41 D.FR SW PUMP P.41D FAILS TO RUN PP.SWP41D.FS SW PUMP P.41D FAILS TO START VL.SWV65.CL SW DISCHARGE GATE VALVE SW.V65 TRANSFERS CLOSED VL.SWV67.CL SW DISCHARGE GATE VALVE SW.V67 TRANSFERS CLOSED VL.SWV68.CL SW DISCHARGE GATE VALVE SW.V68 TRANSFERS CLOSED VL.SWV70.CL SW DISCHARGE GATE VALVE SW.V70 TRANSFERS CLOSED XX.OSP.XX OFFSITE POWER UNAVAILABLE XX.SSIGNAL.XX St SIGNAL PRESENT XX.TRAINA.XX TRAIN A SUPPORT SYSTEMS UNAVAILABLE XX.TRAINB.XX TRAIN B SUPPORT SYSTEMS UNAVAILABLE SECTION 3.4 SERVICE WATER SSPSS 1993 BC00U**3DCCI
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- u i is y op.es Cooling Tower SEnvlCE WATER Vemitation sysitu System figure 3.4-3 SSPSS-1993 O
.. l l l - ) 1 Attachment B . SW Maintenance Data Details This section contains the basis of three generic dato distributions used for SW maintenance i duration. These are included for illustration purposes, to show the type of generic industry data that I is used in this analysis. All the generic dato distributions are taken from Reference 4.
. ZMPMSD. Maint, Darction Pumps 72 hour Tech Spec . ZMPLSD Maint. Duration Pumps .168 hour Tech Spec . ZMPSWD Maint. Duration PCC / SW pumps with no LCO (modified from ZMPNSD for pumps with no LCO to account for the high priority SW and PCC pump maintenance is expected to be treated even with no LCO).
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