ML20236D153
| ML20236D153 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 02/11/1987 |
| From: | PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | |
| Shared Package | |
| ML20236D095 | List: |
| References | |
| NUDOCS 8710280045 | |
| Download: ML20236D153 (12) | |
Text
Attachment I 2870008860
- Page 10 of 15
~ i ELECTRICAL ENGINEERING DIVISION )
N3-1, 2301 MARKET STREET l 1
Safety Evaluation for Mod #2079 Peach Bottom Atomic Power Station - Units 2 and 3 File: SAFETY 2 (Fire Protection)
DOCTYPE 265 I SUBJECTi This modification corrects problems with five motor-operated valve circuits which are not in compliance with Appendix R to 10CFR50.
In each case, spurious operation of the valves could occur for a fire in areas through which valve control cables are routed and in which operation of the valves is relied upon for safe shutdown.
This modification corrects these problems by either relocating valve controls to fire areas in which operation of the valves is not relied upon for safe shutdown or by making logic changes in ,
the control circuits to prevent spurious operations.
II CONCLUSION:
HPCI, RCIC and ESW are safety-related systems. An unreviewed i!
safety question is not involved. A change to the Technical i specifications is not required. The capability to safely shut /
down the plant in the event of a fire is maintained. This modification does not require a license amendment or prior NRC approval. A significant hazards consideration is not involved. A revision to the UFSAR is required.
III DISCUSSION:
MO-2-23-15: HPCI INBOARD STEAM SUPPLY ISOLATION VALVE Failure of control cables in Fire Area 25 and 6 South could spuriously close thic valve and disable HPCI operation for Unit 2.
The power and control cables for this valve are from MCC 20B36 (A channel emergency power) located in Fire Area 6 South. The control cables and reversing motor starter, for this valve will be relocated to a new control box in the Unit 2 M-G set room of the Radwaste Building. The power feed remains from compartment 14 of MCC 20B36. Power to the valve for alternative shutdown is supplied from the B channel of the Unit 2 emergency 4kV system through a power transfer switch. In the normal mode, power to the valve will be from MCC 20B36.
8710280045 871016 7 DR ADOCK 05000
SE Mod 2079 q
Attachment I 2870008860 Page 11 of 15 The transfer switch will be annunciated when in the alternative shutdown position. i MO-3-23-15: HPCI INBOARD STEAM SUPPLY ISOLATION VALVE Failure of control cables in Fire Area 25 could close this valve l and disable the HPCI system for Unit 3. The power and control cables for this valve are from MCC 30B36 (A channel emergency power) .
The control cables and reversing motor starter for this valve will be relocated to a new control' box in the Unit 3 MG set room of the l Radwaste Building. The power feed remains from compartment 14 of MCC 30B36. To provide pcwer to the valve for alternative shutdown, a feed from the B channel Unit 3 emergency 4kV system will power
, the valve. To provide this capability, a power transfer switch will be installed to feed the new control box. In the normal mode, power ' to the valve will be from the 30B36 MCC. In the alternative shutdown mode, power to the valve will be from the B channel emergency 4kV system. The transfer switch will be annunci- ;
ated when in the alternative shutdown position. f MO-2-13-15: RCIC STEAM LINE ISOLATION VALVE Failure of. control cables in Fire Area 6 North could spuriously close this valve and disable RCIC operation for Unit 2. The power and control cables for this valve are from compartment 21 of MCC 20B37 located in Fire Area 6 North. The control cable and reversing motor starter for this valve will be relocated to a new !
control box in the Unit 2 MG set room of the Radwaste Building.
The power feed will remain from its present source for both normal and alternative shutdown operation.
MO-3-13-15: RCIC STEAM LINE ISOLATION VALVE Failure of control cables in Fire Area 13 North could spuriously close this valve and disable RCIC operation for Unit 3. The power and control cables for this valve are from compartment 21 of MCC 30B37 located in Fire Area 13 North. The control cable and reversing motor starter' for this valve will be relocated to a new control box in the Unit 3 MG set room of the Radwaste Building.
The power feed will remain from its present source for both normal and alternative shutdown operation.
i MO-0498: EMERGENCY SERVICE WATER DISCHARGE VALVE The ESW reservoir isolation valve MO-0498 provides a flowpath back to the discharge pond during ESW operations whenever the ESW pumps and normal heat sink, the Conowingo Pond, are available. MO-0498 is closed only when use of the emergency heat sink is required.
The Peach Bottom Appendix R Shutdown Analysis identified a condition that a hot short of one of the conductors in either control cable ZDOB5643D or ZDOB5643E could cause MO-0498 to close.
Closure of MO-0498 could cause the emergency diesel generators to trip unless the valve is opened within three minutes. Recognition of the need to open and manual operation of the valve within three minutes is not possible.
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'i 7 Attachment I-
~ '2870008840Page 12 of:15
'This' modification provides a pushbutton on the C123 panel which- '
i
- prevents. energizing the '"close" contactor coil: when a time-delay-;
control: relay is . de-energized. To stroke: MO-0498 closed, thel pushbutton is' depressed which energizes ' the time, delay relay and permits a close : signal to ener s ize the clo'se contactor. The timer 'is ' set for . a' period ' gre'avr than the stroke time for
- MO-0498. to allow adequate time to stroke ~ the' valve. After this time period, a seal-in which shunts the pushbutton. contact drops out and:the close contactor coil is' isolated.
A review of-the two affected design basis events indicates that sufficient time exists to allow manual repositioning of MO-0498 prior - to- establishing cooling using the emergency heat sink.
'First, for the probable maximum flood, Peach' Bottom FSAR Question 2.4.C states ' that . about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> are needed to raise the river level elevation ' f rom +113 '-0" to +115 '0" (Conowingo Datum) when
-the predicted river flow is greater than 840,000 CFS. This.is a limiting _ condition for operation which requires the reactors be L placed in cold shutdown using . normal operating procedures.
-Second, following an uncontrolled -water ' release from Conowingo Dam, Peach' Bottom USAR Question 2.4.C states that approximately
~
i 1.5' hours exist before the water level at the intake structure drops to the plant low water design level. This time frame-is conservative since it assumes the Pond is at its minimum level at j the initiation ~ of. the event and, there is no inflow to the Pond l from the Susquehanna River.
By changing the remote manual capability of closing the- valve from panel- C123 to'. include a second pushbutton, two logic signals which cause automatic closure are eliminated by thic modification.
In the pre-mod state , the first close signal results. from an emergency diesel generator start signal which starts the emergency cooling water (ECW) pump (OOP186) after a time delay. If either ESW pump has sufficient discharge pressure, the ECW pump will shut down. However, if both ESW pump discharge pressures are low, the
. logic signal opens the ECW pump discharge valve, MO-0841, and q closes MO-0498. The ESW booster pumps (OAP163 and OBP163) start I and closed loop cooling is initiated. The second automatic close signal results from both~ service water pump structure sluice gates j]
closing for either unit. The logic in turn closes Mo-0498 and (
. starts the ESW booster pumps. Cooling is established using an ESW pump and an ESW booster pump which discharges back to the emergency cooling tower. The water is cooled in the tower and 3 returned by gravity feed to the service water pump structure. i This modification eliminates automatically establishing either one !
of these closed loop cooling paths. However annunciation in the !
main control room to warn the operator to manually close the j MO-0498 valve is provided by this modification for each of the ~;
l; automatic logic conditions which are being eliminated. j 1
In addition to the above events, a loss of both ESW pumps was ,
evaluated since heat rejection would then be provided by closed loop cooling using the emergency cooling water pump {4 1
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I SE Mod 2079 Attachment I
' v ge 3 es 2870008860
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(OOP186) and emergency heat sink. This accident is not considered credible since it requires a double active failure. However, if this situation should occur, closed loop cooling can be established by manually shutting MO-0498 and starting one of the two emergency service water booster pumps (OAP163 or OBP163) .
Cooling of safeguard equipment commences immediately with the establishment of emergency cooling water pump flow, however the water inventory in the emergency heat sink is dumped to the discharge pond until MO-0498 is shut. If MO-0498 is shut by plant personnel within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of initiating emergency cooling, only 16 percent of the consumable inventory will be lost. Section 10.24 of the UFSAR states that the inventory of water within the tower is adequate for 1 week of operation without makeup. Based on continuous cooling tower operation at the rated flow condition, the total water consumed after 7 days is'3,000,000 gallons.
Since sufficient time exists for an operator to reposition MO-0498 manually before establishing cooling using the emergency heat sink, the impact of this modification on the safe shutdown of the plant is negligible. l There are no new electrical load requirements as a result of this.
modification. Powering MO-2-23-15 and MO-3-23-15 from the B safe-guard bus for alternative shutdown is acceptable because the five horse power load from each valve motor loads the bus only during the valve stroke time. Also, similar valve loads on the B bus l J
will not be used during alternative shutdown.
UPSAR Single line drawings and P and ids will be updated to reflect this modification. Sections 5.4.2, 4.7, 6.4, 10.9 and 10.24 have been reviewed in making this determination. !
Since this modification does not involve any radwaste systems, IE ,
i Circular 80-18 is not applicable.
IV 10CFR50.59 CHANGES TESTS AND EXPERIMENTS:
The following conclusions can be made regarding this modification:
- 1. Technical Specification Sections 3.5C, 4.5C, 3.2,4.2, 3.5D, 3.9C 4.9C 3.11B, 4.llB, 3.12, 4.12 and the associated bases for these sections have been reviewed. Changes are not i l
required because this modification does not change the HPCI, RCIC or ESW systems as described in the Technical Specifica- i tions. The MO 2-23-15 and MO 3-23-15 valves are normally powered from safeguard channel A power and channe.1 separation is maintained by this modification.
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2870008860
.~ Attachment I Page'14 of.15 l
- 2. An unreviewed safety question is not involved because of the -
following reasons:
f
~a) The probability of occurrence or the consequences of an accident or malfunction of equipment important to safety previously evaluated in the safety analysis report is l not' increased. 'This modification relocates motor con- )
trols for.MO-2-13-15, MO-3-13-15, MO-2-23-15 and j MO-3-23-15.- For.the MO-2-23-15 and MO-3-23-15 valves, j the A channel emergency power supply is maintained for j the new transfer switch in its normal condition. In the~ l alternative shutdown mode, the abnormal condition is l annunciated in the main control room. Since it is not necessary to consider a design basis accident or seismic event coincident with a design basis fire and the con-current loss of offsite power, the alternate source of safeguard power to the valves with the transfer switch in the. emergency mode does not violate safeguard channel separation criteria. The function of the HPCI and RCIC systems are unchanged by relocating the controls for the steam line. isolation valves.
Annunciation of conditions which require MO-0498 to be closed will provide the operators with sufficient time to close'this valve. Therefore, eliminating the automatic closing capabilities for MO-0498 does not reduce the mar-gin of safety.
b) The possibility for an accident or malfunction of a different type than any evaluated previously in the safety analysis report is not created. 'The operability of the HPCI, RCIC and ESW systems are unchanged by
. .these~ modifications. Although automatic operation is removed from MO-0498, annunciation is provided and sufficient time exists for an operator to recognize the need to close MO-0498 and establish closed loop cooling.
c) The margin of safety as defined in the basis for any Technical Specification is not reduced. This modifica-tion improves the margin of safety by providing a means of supporting HPCI, RCIC and ESW operation for those .
fire areas where they are relied u nL, for [. E/
. Te </, n h a l .rp e e l f. p f s,on Jections 3.t c.,4. 5C v.1 safe
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-V 10CFR50.92 SIGNIFIChMT HAZARDS DETERMINATION: M
- k,lI'thgM s/e This determination is not applicable because a license amendment / \
is not required. .
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SE Mod.>2079 Attachment I 1
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. I
'VI iAPPROVALS:-
Prepared'bys' Date: ' /!d~/6 7-(Responsible Engineer)
. Reviewed by: ._
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ATTACFNENTJ 11 ,. Page 1 of 2 ,
.' i 1
High/ Lod Pressure Interfaces A. Main Steam Isolation Valves-(MSIV's)'(AO-2-80A & 86A)-
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~ The selection of the MSIV's as a high/ loa pressure interface-
. ls not required by the guidance contained in Generic Letter 81-12. The
?
l LMSIV's will be deleted from' TABLE A-5 to alleviate confusion with regards~to conpliance.wlth the Appendix R. criteria.
EThe selection of-the MSIV's as a high/ low pressure Interface was-conservative since the piping downstream of the MSIV's ls designed for rated reactor-pressure. A spurious opening of both MSIV's in any or all of the main stean lines would not result In a failure of the downstream piping.
B. . SCRAM' Discharge Volune (SDV)-Vent and Drain . Valves (CV-3-32A, 35A, 33 & 36) !
The SDV vent and drain valves will be deleted fran TABLE A-5
~
since they are not required to'be ident1 fled as a high/ low pressur.e interface by the guidance contained in Generic-Letter 81-12. This should alleviate 'any confusion with regards to comollance with the' Appendlx.R criteria.
TTm selection of the SDV vent and drain valves as high/ low pressure interfaces was conservative. A spurious opening of the redundant valves in the vent and drain lines from the SDV would not createla LOCA in the interfacing piping, since this piping is routed to a vented sunp. The inherent fall safe (closed) nature of the' vent an draln. valves makes the occurrence of the spurious opening
'i ncredi bl e. - .
C. Reactor Head Vents (AO-2-17 & 18)
The discussion regarding the reactor head vent valves In Table A-5. concludes that the spurious opening of these valves could cause an unacceptable increase in drywell temperature. However, additional analysis of this spurious operation has been perforced and it has been concluded that this occurrence will not result in unacceptable drywell conditions nor will it adversely affect the ability to shutdown from an Appendix R. fire. Therefore, TABLE A-5 will be revised to indicate i that the sourlous coeration of the head vent valves does not prevent eculpment required for safe shutcown f ran functioning.
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Attachment II Page'.2 ofL2.
D. ' RHR Shutdown Cooling Suction Line Isolation Valves (MO-10-17 & .18)
The discussion in. TABLE A-5, regardirig the: spurious opening of the shutdown' cooling isolationLvalves Is based on Information
. contained'In General Electric Co. Report NEDC-31339 "BWR Owners' Group Assessment of Emergency Core Cooling System Pressurizatico in. Bolling
' Water Reactors " . This report has been submitted 'tc the NRC. (Letter, T. A. Pickens, BWROG, to .C. J. Heltemes, Jr., NRC dated Decerrber 10, l
'1986). 'It identifies the inherent pressurization margin in low pressure l
- ECCS. piping and cites various Instances where such piping has been )
- overpressurized without. failure. This report has been reviewed for j applicability to Peach Bottom,~and it had been concluded that since it q ls r,npilcable, the RHR low pressure shutdown cooling piping Is not l expected to fall as a result of a spurious operation-of-the Isolation i valves.
4 Prepared by: W. J. Brady October 13, 1987 -
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1 2 ATTACFf4ENT III - Page 'l of l' .Il
-NUREG 0783 Suppression Pool Temperature LImlt The .. NUREG-0783 bulk suppression chant >er temperature limit of .
. 190F~lmposed on Peach Bottom is not exceeded during an Appendix R fire ,-
In any fire area. RHR Punp NPSH limits, based on conservative >
assumptions, dictated that the torus temperature not exceed .183F; and' this limit was not exceeded for any fire area. .'No credit was taken-
~
for contairmant 'pressurIzat ton which would be expected to occur.
- Therefore, the. criteria'In'NUREG-0783 has been met.
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I Prepared by: W. J. Brady October 13, 1987 (
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Page 1 of 1
.l Attachment IV ;
l Cold Shutdown Repairs i
I The NRC requested that PECo provide a description of the cold j shutdown repairs used for safe shutdown.
The ability to perform a controlled depressurization and cooldown !
during an Appendix R fire may rely on the use of safety relief valves.
Since instrument nitrogen cannot be assumed to remain available , only the limited quantity of nitrogen in the ADS valves' accumulators is available to manually operate the SRV's. This limited nitrogen supply may not be sufficient to maintain reactor pressure control for the i duration of the postulated event. The ADS valves are equipped with a l 100 day backup nitrogen supply with a normally closed automatic isolation valve which must be manually opened to resupply the ADS j valves. This backup system cannot be assumed to be available since the ;
AC power which is required to open this valve may be lost. In l addition, because of valve design, local manual operation of this valve is not possible.
A repair procedure is used to provide a means to resupply the ADS j SRV's with an N2 S pply under Appendix R fire conditions. The repair is accomplished by placing a preconstructed bypass line on the test taps located both upstream and downstream of the SV-8130A,B (SV-9130A,B) solenoid valves. The bypass line is to be placed in service only when ,its use is required as prescribed by the T-300 Fire Guides.
The following is a list of the Fire Areas which may require this repair:
COLD SHUTDOWN REPAIRS Fire Area Unit 2 Unit 3 2 SV-8130A SV-9130A 4 SV-8130A SV-9130A 6N SV-8130B 6S SV-9130A 13N SV-9130B 26 SV-9130A 31 SV-9130A and B 1 32 SV-9130A and B l I
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Attachment.V Page 1 of 2 Manpower Availability y I
The NRC requested.that PECo~ provide information on the difference between -the ' available' on - site manpower and the required manpower .to -
The.
achieve - safe . shutdown during an ' Appendix R Fire - Scenario.
following provides ithe basis for the available manpower and a list, by i Fire Area, of the manpower required:
Manpower availability is based on Technical Specification 6.2.2 for Facility Staff. The members of the fire brigade were not assumed to be- .
l available to' shut the plant down during the~first hour of an Aependix R l fire event for safe' shutdown fire areas. Although additional personnel are.
normally available, 8 on-duty shift personnel were used for Appendix R purposes, c,
4 CNS/10787 i
8a W oc!. Arthchmmnt"V- Page 2 of 2 9 . ., o . <-
^P i TIFI APIA MANPO*.TER FIOUIPIMECS .l k l '
MANPO*JER MANPO'JER AVAILABLE -PIOUIPID TIPI APIA MANUAL OPERATIONS PIOUIPID 8 3 No 1 8 '8 i 2
.Yes ,
8 8 4
Yes ,
8 4 '
5 Yes 8 7 6N Yes 8 8 6S' Yes 8 3 l 9 No '
8 3
- 10. No 8 3 ;
12 No
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8 8 13N Yes 8 7 13S .Tes 8 3 16 No 8 3-17 Tes '
8 3 18 - No po 8 3 39 8 4 -
20 Tes
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.21 No 8 3 2 2 . ... No 3 8 Tes
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Tes 26- 8 3 1
'27 No 8 3 30 Tes .
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31 Tes 0 8
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8 5 33 Tes ,
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~Tes 8 8
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37 Tes /
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51 No B f 8 3 32 No 8 3 53 Eo 7 8 .4 54 Tes 3 {
8 55 No f 1
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