ML17338B208
| ML17338B208 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 10/16/1979 |
| From: | Eisenhut D Office of Nuclear Reactor Regulation |
| To: | Robert E. Uhrig FLORIDA POWER & LIGHT CO. |
| References | |
| NUDOCS 7910260301 | |
| Download: ML17338B208 (25) | |
Text
OgTOBER 1 6 1979 Docket Nos'.:
50-250 50-251 Dr. Robert E; Uhrig, Vice-President Advanced Systems and Technology Florida Po>m'r and Light Company P. 0.
Box 529100 Miami, Fl orida 33152
Dear Dr. Uhrig:
SUBJECT:
NRC RE(}UIREMENTS FOR AUXILIARYFEEDMATER SYSTEMS AT TURKEY POINT PLANT, UNITS 3 AND 4 The purpose of this letter is to advise you of our requirements for the auxiliary feedwater systems at the subject. facility.
These requirements were identified during the course of the NRR Bulletins and Orders Task Force review of operating reactors in light of the accident at Three Mile Island, Unit 2.
Enclosure 1 to this letter identifies each of the requirements applicable to the subject facility.
These requirements are of two types, (1) generic requirements applicable to most 1/estinghouse-designed operating plants, and (2) plant-specific requirements applicable only to the subject facility.
Enclosure 2 contains a generic request for additional information regarding auxiliary feedwater system flow "requirements.
The designs and procedures of the subject facility should be evaluated against the applicable requirements speci. fied in Enclosure 1 to determine the degree to which the facility currently conforms to these requirements.
The results of this evaluation and an associated schedule and comoitment for implementation of required changes or actions should be provided for NRC staff review within thirty days of receipt of this letter.
Also, this schedule should indicate
. your date for sub'>ittal of information such as design changes, procedure changes
~>~
or Technical Specification changes to be. provided for staff review.
You may also 4~
"provide your response to the items in Enclosure 2 at that time.
In addition to the requirements identified in this letter, other requirements which may be applicable to the subject facility are expected to be generated by the Bulletins and Orders Task Force.
Such requirements are those resulting from our review of'he loss-of-feedwater event and the small break loss-of-coolant
'ccident as described in the Meetinghouse report RCAP-9600, "Report on Small II orr>est~
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Dr. Robert E. Uhrig OCTOBER y g ]gyg Break Accidents for-Westinghouse NSSS System."
Our,specific concerns include systems reliability (other than the auxiliary feedwater system),
- analyses, guidelines and procedures for operators, and operator training.
Me plan to identify, in separate correspondence, the requirements resulting from the additional items from the Bulletins and Orders Task Force review.
Sincerely, Original Signed By P,L, teaedcD Qarrell G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation
Enclosures:
As stated DIST:
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50-250 50-251 UNITED STATES NUCLEAR R EG ULATORY COMMISSION WASHINGTON, D. C. 20555 OCTOBER
~
g ]97It Dr. Robert E. Uhrig, Vice-President
'dvanced Systems and Technology Florida Power and Light Company P.'0.
Box 529100 Hi ami, Fl orida 33152
Dear Dr. Uhrig:
SUBJECT:
NRC REQUIREMENTS FOR AUXILIARYFEEDWATER SYSTEMS AT TURKEY POINT PLANT, UNITS 3 AND 4 The purpose of this letter is to advise you of our requirements for the auxiliary feedwater systems at the subject facility.
These requirements were identified during the course of the NRR Bulletins and Orders Task Force review of operating reactors in light of the accident at Three Mile Island, Unit 2.
, Enclosure.l to this letter identifies each of.the requirements applicable to the subject facility.
These requirements are of two types,
( 1) generic requirements applicable to most Westinghouse-designed operati ng plants, and (2) plant-specific requirements applicable only to the subject facility.
Enclosure 2 contains a generic request. for additional information regarding auxiliary feedwater system flow reguirements The designs and procedures of the subject facility should be evaluated against the applicable requirements specified in Enclosure 1 to determine the degree to which the facility currently conforms to these requirements.
The results of this evaluation and an associated schedule and comIitment for implementation of required changes or actions should be provided for NRC staff review within thirty days of receipt of thi s letter.
Also, thi s schedule should indicate your date for submittal of information such as design changes, procedure changes or Technical Specification changes to be provided for staff review.
You may also provide your response to the items in Enclosure 2 at that time.
In addition to the requirements identified in thi s letter, other requirements which may be applicable to the subject facility are expected to be generated by the Bulletins and Orders Task Force.
Such requirements are those resulting from our review of the loss-of-feedwater event and the small break loss-of-coolant accident as described in the Westinghouse report WCAP-9600, "Report on Small
Dr. Robert
.E. Uhrig i)70 Break Accidents for Westinghouse NSSS System."
Our specific concerns include systems reliability (other than the auxiliary feedwater system),
- analyses, guidelines and procedures for operators, and.operator training.
We plan to identify, in separate correspondence, the requirements resulting
. from the additional items from the Bulletins and Orders Task Force review.
Sincerely, Darrell G.
Ei senhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation
Enclosures:
As stated
Robert E. Uhrig Florida Power and Light Company 3
CC:
Mr. Robert Lowenstein, Esquire Lowenstein,
- Newman, Reis and Axelrad
'025 Connecticut
- Avenue, N.M.
Suite 1214 Washington, D.
C.
20036 Environmental and Urban Affairs Library Fl orida International Universi ty Niami, Florida 33199 Mr. Norman A. Coll, Esquire
- Steel, Hector and Davis 1400 Southeast First National Bank 8uilding l1iami,'l ori da 33131 Mr. Henry Yaeger, Plant Manager Turkey Point Pl ant Florida Power and Light Company P.
0.
Box 013100 Miami, Florida 33101 Mr. Jack Shreve Office of the Public Counsel Room 4, Holland 8uilding Tallahassee, Florida 32304
X. 16 (W)
ENCLOSURE 1 TURKEY POINT UNITS 3 & 4 AUXILIARYFEEDMATER SYSTEMS X. 16. 1 X.16.1.1 S stem Descri tion Confi uration-Overall Desi n
The auxiliary feedwater system (AFMS) for the Turkey Point plant (Units 3 8 4),as shown in Figure 1, consists of three steam turbine driven pumps, i.e.,
one pump normally aligned to each unit and the third pump is a shared standby for either unit.
Each pump normally delivers 600 gpm (8 2775 ft. head) feedwater to the three steam generators (SG) in each unit.
Also, the control room operator can manually direct flow from any pump to all three steam generators of either unit. Undep a design basis accident, only one pump would be required in order to cool the plant down to a condition where the RHR system can be put into operation to continue the safe plant shutdown process.
Primary water supply for the AFWS comes from the seismic Category I condensate storage tanks (CST) of both units.
Each CST has a capacity of 250,000 gallons with a minimum reserved storage capacity of 185,000 gallons of demineralized water.
Mith this quantity of water, the licensee indicated that the unit can be kept at hot standby condition for 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> and then cooled to 350 F, at which point the RHR system c'n be put in service, or the unit can be kept at hot standby condition for about 23 additional hours.
All the manually
operated. valves associated with CST's ar e locked open.
A secondary water supply comes from the non-seismic Category 1 water treatment system.
An additional feedwater supply can be provided from the main feedwater system of the adjacent Units 1 8 2 (non-nuclear power plant).
X. 16. 1. 2 Com onents - Desi n
Classification The AFWS is designed according to seismic Category I requirements.
The AFWS is classified as en engineered safety related system and its associated instrumentation and controls are designed accordingly.
X. 16. 1. 3 Power Sources The turbine driven pumps are supplied with steam from the main steam line of either or both units upstream of the MSIV.
The operator normally selects the steam supply from the Unit which has lost its normal feedwater supply.
The turbines have an atmosphere exhaust.
Steam
'can also be supplied from the Unit having normal feedwater supply and from an auxiliary steam system connection to Units 1
8 2.
The turbine driven pump steam supply line has a normally closed AC motor operated valve in series with a normally closed DC solenoid air operated valve.
The pump discharge control valves are DC solenoid operated air valves.
X. 16 ~ 1.4 X. 16 ~ 1.4. 1 Instrumentation and Control Controls The steam generator water level is manually controlled by the control room operator using either one of the DC'solenoid operated air valves.
Local manual operation of these valves can be performed on loss of compressed air.
The AFW pump feedwater discharge rate is always greater than the turbine steam consumption when the steam pressure is higher than 120 psig.
When the steam pressure is reduced to 120 psig, the RHR system is started and the AFW pumps are shut 'dawn.
Information Available to 0 erator Low water level in Cfire condensate storage tank* will a1arm and annunciate in the main control room.
In addition, AFW flow indication, SG water
- level, and control valve position indication are provided in the control room.
Initiatin Si nals for Automatic 0 eration All three AFW pumps will automatically start by any of the following signals from either Unit:
(a) safety injection (b) low-low water level in any of the three steam generators
'I (c) loss of voltage on both 4160V.buses (d) loss of both main feedwater pumps.
Any one of these signals will also automatically open the normally closed motor operated and air operated valves in series which isolate the main steam line from the steam supply header of each AFW pump turbine.
Air to operate the AFW control valves to the steam generators is supplied when the steam supply valves commence opening.'he AFWS can also be started manually in the control room or from the local station.
~Teetin
'The Turkey Point Units 3 and 4 Technical Specifications require the following testing of the auxiliary feedwater system.
1)
Monthly test of each auxiliary feedwater pump to run for 15 minutes and verify a flow rate of 600 gpm to the steam generators.
2)
Tests of auxiliary feedwater discharge valves during the monthly pump tests.
. 3)
Tests of steam supply and turbine pressure valves during monthly pump tests.
These tests are designed to verify the operability of the auxiliary feedwater system and its ability to respond properly when required.
Technical S ecifications The Turkey Point Units 3 and 4 Technical Specifications provide for the following limiting conditions for operation with respect to the Auxiliary Feedwater System:
1)
Two out of three AFMS pumps must be operable for single nuclear unit operation.
2)
Three out of three AFWS pumps must be operable for dual nuclear unit operation.
The licensee advised that the type of periodic (monthly) testing performed for the AFMS includes full flow path discharge to the SG's, i.e.,
a single actuation of AFMS and delivery to SG s while power is being produced.
3)
The.condensate storage tank must contain a minimum of 185,000 gallons of water.
4)
System piping, inter locks and valves must be operable.
If any of the above conditions cannot be met within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, the reactor must be shut down and the reactor coolant temperature must be reduced to less than 350 F.
X. 16. 2 Reliabilit Evaluation X. 16. 2. 1 Dominant Failure Modes The AFMS simplified flow diagram for Turkey Point Unit 3 is illus-trated in Figure 1.
This AFWS design reflects a redundant, highly
- shared, system between Units 3 and 4.
Operation of any one of the three steam turbine driven pumps would be expected to result in successful decay heat removal from either Units 3 or 4.
Accordingly, the success oriterion selected for this reliability evaluation was:.
Failure of AFWS is insufficient AFWS flow from one AFMS pump to 2 of 3 steam generators in one unit.
The following failure modes were found to dominate the demand unavaila-bility of the Turkey Point AFMS ~
LOFW with Offsite AC Available The Turkey Point AFWS was found to be highly redundant in that there was no obvious single faults (active components, manual valves or human errors) identified that dominate the availability of the AFMS.
The periodic testing practice followed involves full flow path testing to the steam generators.
This type of testing is of quality in that it yields an advantage on detectability of valves that might be mispositioned through human errors.
Also, the AFWS manual valves are locked open and this practice further reduces the chance of inadvertent closure through human error.
Several unlikely common mode vulnerabilities were identified that might serve to limit the availability of the highly redundant Turkey Point AFWS; their ultimate impact should be further considered in a longer time assessment.
These were:
a)
The possible common sharing of the lube oil cooling by'the service (city) water system which is DC powered.
b)
The potential for common disabling of Unit ¹3 and/or ¹4 AFWS by a single failure of the connecting piping between the headers in the AFWS pump discharge and steam supply paths.
LOFW with Onl Onsite AC Available The impact of shared emergency diesel generators (EDG) and their contribution to the unavailability of the Turkey Point AFWS were estimated to be very small.
The steam admission valves to the turbine pumps are AC operated, but either of the two EDG's oper ating would suffice to operate at least one or more of the three AC valves in each header in Unit 3 and 4.
- Further, the human can serve as backup to open these valves if for some reason, the AC or DC valves in either Unit 3 or 4 steam admission header failed to operate electrically.
The dominant faults appear to remain similar to those discussed for the preceeding LOFM transient event.
LOFW with Onl DC Available As noted above the steam admission valves are AC oper ated in Turkey Point Units 83 and 84.
The dominant fault contribution for this event was assessed to be failure of the human to open at least one of the steam admission valves by local manual action.
The licensee estimated that such actions could be accomplished within about 10 minutes.
X.16. 2. 2 Princi le De endencies Identified One dependency identified was the AC dependency for the steam admission valves that, for the event including complete loss of AC, would require local manual action to initiate the AFMS.
Several additional dependencies were identified that should be considered further,but on a longer term consideration as to their ultimate impact on the AFWS.
These were (a) the potential for common lubrication cooling faults in the service (city) water system and (b) the potential for common disabling of the AFWS due to breaks in the single line in the AFMS discharge headers and in the steam supply headers to all turbine driven AFM pump turbines.
X. 16. 3 Recommendations for this Plant The short-term recommendations (both generic, denoted by GS, and plant-specific) identified in this section represent actions to improve AFW system reliability that 'should be implemented by January 1, 1980, or as soon thereafter as is practicable.
In general, they involve upgrading of Technical Specifications or establishing procedures to avoid or mitigate potential system or operator failures.
The long-term (both generic, denoted by GL, and plant-specific) recommendations identified in this sec-tion involve system design evaluations and/or modifications to improve AFW system reliability and represent actions that should be implemented by January 1, 1981, or as soon thereafter as is practicable.
X. 16. 3. 1 Short-Term Recommendation GS The licensee should propose modifications to the Technical Specifications to limit the time period that one AFW system pump and its associated flow train and essential instrumentation can be inoperable.
The outage time limit and subsequent action time should be as required in current Standard Technical Specifications; i.e.,
72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, respectively.
2.
Recommendation GS-2 The licensee should lock open single valves or multiple valves in series in the AFW system pump suction piping and lock open, other single valves or multiple valves in series that could interrupt all AFW flow.
Monthly inspections should be per formed to verify that these valves are
locked and in the open position.
These inspections should be proposed for incorporated into the surveillance requirements of
/
the plant Technical Specifications.
See Recommendation GL"2 for the longer term resolution of this concern.
,J ~
3.
Recommmendation GS-4 " Emergency procedures for transferring to alternate sources of AFM supply should be available to the plant operators.'hese procedures should include criteria to inform the operators
- when, and in what order, the transfer to alternate water sources should take place.
The following cases should be covered by the procedures:
The case in which the primary water supply is not initially available.
The procedures for this case should include any operator actions required to protect the AFM system pumps against self-damage before water flow is initiated; and, The case in which the primary water supply is being depleted.
The procedure for this case should provide for transfer to the alternate water sources prior to dra)g)ng of the primary water supply.
4.
Recommendation GS The as-built plant should be capable of providing the required AFW flow for at least two hours from one AFW pump train independent of any alternating current power source.
If manual AFW system initiation of flow control is
10 required following a complete loss of alternating current power, emergency procedures should be established for manually initiating and controlling the system under these conditions.
Since the water for cooling the lube oil for the turbine-driven pump may be dependent on alternating current power, design or procedural changes shall be made to eliminate this dependency as soon as practicable.
Until this is done, the emergency procedures should provide for an individual to be stationed at the turbine-driven pump in the event of the loss;of all alternating current power to monitor pump bearing and/or lube oil temperatures.
If necessary, this operator would operate the turbine-driven pump in an on-off mode until alternating current power is restored.
Adequate lighting powered by direct current power sources and communications at local stations for manual initiation and control of the AFW system should also be provided if manual initiation and control of the AFW system is needed.
-(See Recommendation GL-3 for the longer term resolution of this concern).
5.
Recommendation GS The licensee should confirm flow path availability of an AFW system flow train that has been out of service to perform periodic testing or maintenance as follows:
Procedures should be implemented to require an operator to determine that the AFW system valves are properly aligned and a second operator to independently verify that the valves are properly aligned.
The 1 icensee should propose Technical Speci ficati ons to assure that prior to plant startup following an r
extended cold shutdown, a flow test would be performed to verify the normal flow path from the primary AFW system water source to the steam generators.
The flow test should be conducted with AFW system valves in their normal alignment.
.6.
Recommendation GS The licensee should verify that the automatic start AFW system signals and associated circuitry are safety-grade.
l If this cannot be verified, the AFW system automatic initiation system should be modified in the short-term to meet the functional requirements listed below.
For the longer 'term, the automatic initiation signals and circuits should upgraded to meet safety-grade requirements as indicated in Recommendation GL-5.
The design should provide for the automatic initiation-of. the auxiliary feedwater system flow.
The automatic initiation signals and circuits should be designed so that a single failure will not result in the loss of auxiliary feedwater system function.
Testability of the intiation signals and circuits shall b'e a feature of the design.
The initiation signals and circuits should be powered from the emergency buses.
Manual capability to initiate the auxiliary feedwater system from the control room should be retained and
12 should be implemented so that a single failure in the manual circuits will not result in the loss of system function.
The alternating current motor-driven pumps and valves in the auxiliary feedwater system should be included in the automatic actuation (simultanous and/or sequential) of the loads to the emergency buses.
~'I The-automatic initiation signals and circuits shall be designed so that their failure will not result in the loss of manual capability to intiate.the AFM system from the control room.
X.16.3.2 Additional Short Term Recommendations The following additional short term recommendations resulted from the staff's Lessons Learned Task Force review and the Bulletins 8 Orders Task Force review of AFM systems at Babcock 8 Milcox-designed operating plants subsequent to our review of the AFM system designs in W-and C-E-designed operating plants.
They have not been examined for specific applicability to ths facility.
1.
Recommendation - The licensee should provide redundant level indications and,'i low level alarms in the control room for the AFM system primary water supply to allow the operator to anticipate the need to make up water or transfer to an alternate water supply and prevent a low pump suction pressure condition from occurring.
The low level alarm setpoint should allow at least 20 minutes for operator actions, assuming that the largest capacity AFM pump is operating.
13 2.
'ecommendation
- The licensee should perform a 72-hour endurance test on all AFM system pumps, if such a test or continuous period of operation has not been accomplished to date.
Following the 72-hour pump run, the pumps should be shut down and cooled down and then restarted and run for one hour.
Test acceptance criteria should include demonstrating that the pumps remain with design limits with respect to bearing/bearing oil temperatures w
and vibration and that pump room ambient conditions (temperatures, humidity) do'ot exceed environmental qualification limits for safety-related equipment in the room.
3.
Recommendation - The licensee should implement the following requirements as specified by Item 2.1.7.b on page A-32 of NUREG-0578:
"Safety-grade indication of auxiliary feedwater flow to each steam generator shall be provided in the control room.
The auxiliary feedwater flow instrument channels shall be powered from the emergency bused-.consistent with satisfying the emergency power diversity requirements for the auxiliary feedwater system set forth in Auxiliary Systems Branch Te'chn-nical Position 10-l,of the Standard Review Plan, Section 10.4.9."
4.
Recommendation - Licensees with plants which require local manual realignment of valves to conduct periodic tests on one AFH system train and which have only one remaining AFW train available for
14 operation, should propose Technical Specifications to provide that a dedicated individual who is in communication with the control room be stationed at the manual valves.
Upon instruction from the control room, this operator would re-align the valves in the AFW system train from the test mode to its operational alignment.
I X. 16. 3. 3
~Lnn -Term Long-term recommendations for improving the system are as follows:
Recommendation
.GL At least one AFW system pump and its associated flow path and essential instrumentation should auto-matically initiate AFW system flow and be capable of being operated independently of any alternating current power source for at least two hours.
Conversion of direct current power to alternating current is acceptable.
e 2.
Recommendation - GL-5 The licensee should upgrade the AFW system automatic initiation signals and circuits to meet safety-grade requirements.
3.
Recommendation
- The AFW pump discharge lines and turbine driven AFW pump steam supply lines for each unit combine into single lines through which all water and steam respectively from either unit must flow.
A pipe break in either of these single flow paths would cause loss of the capability to provide AFW flow to all the steam generators of one unit.
The licensee should evaluate the consequences of a
15 postulated pipe break in these sections of the AFW discharge or'team
- supply, assuming a concurrent single active failure and
- 1) determine any AFW system modifications or procedures necessary to detect and isolate the break, and direct the required AFW flow to the steam generators before they boil dry or, 2) describe how the plant can be brought to a safe shutdown condition by use of other available systems following such a postulated pipe break.
4.
Recoranendation The lube oil cooling of the three turbine driven AFW pumps is provided from a common source; namely -the service (city) 1 water system.
The licensee should evaluate this cooling water system to determine if there are potential, common mode (electrical or mechanical) failures that could disable the lube oil cooling for all three turbine driven pumps.
The licensee should provide the results of the evaluation and 1) indicate any system modifications or procedures necessary to prevent a
common mode failure of the lube oil cooling system or 2) provide information that demonstrates that the turbine driven AFW pumps can operate for at least two hours without lube oil cooling water and independent of AC power.
CSl UNI1 250.000 GAL.
FIIOM CONDENSATE IIECOVI:HYSYSlEM (CRS) 400 DC SOLENOID OPERATED AIR VALVES CV2831
'jB-CONTAINMENT MAIN FW LINES TO COND TRANSFER PUMP 401 144 A
143 142 LO LO TO UNIT 4
LO CV2810
~4Aal I
CV2832 140 139 LO I
~IBJ ~
CV2817 240 I
no 244 TO UNIT LO 4
342 343 LO TO UNIT 4
LQ
~JAN I
~BI~
I 344 340 339 141 CV2818 LO I
LO LO
~oAo ~
TURB. DR IVEN PUMPS REQUIRES DC FOR LUBRICATIONCOOLING REQUIRES SERVICE WATER FLOW {CITY WATER)
NC FC POSI TlON INDICATED IN CONT. RM 401 TO COND.
fRANSI.ER PUMI'00 LO FAILS AS IS DC SOV.MODULATING ATM
/
LO LO FI<OM CRS B TRAIN CST UNIT 250,000 GAL.
MOV1403 LEGEND:
FO FAILOPENED FC FAILCLOSED FA FAILAS IS DCl NORMALLYOPENED NORMALLYCLOSED AOR B NC FA TRAIN MOV1404 NC FA A TRAIN MOV1405 85 84B 84A FROM UNIT4 GG 370G ATM TA 83 82B 82A G9 NC 3705 LO LO ATM FROM UNIT4 LO LO TO SGC TO SGB TO SGA CONTAINMENT I MAINSTEAM LINES 119 219 319 MOl OR OPERATED AlR OP E RATED LO LO TC 87 87B 8GA 08 3707 FROM UNIT 4 NCX I
STEAM ADMISSION TO AFWS TURBINES (UNIT 3 SHOWN)
Auxiliary Feedwater Systetn Turkey Point (U>>its 3 a>>d 4)
Fi9<<re 1
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ENCLOSURE 2
Basis for Auxiliary Feedwater System Flow Reouirements As a result of recent staff reviews o< operating plant Auxiliary Feed-water Systems (AFWS), the staff concludes that the design bases and criteria provided by licensees for establishing AFWS requirements for flow to the steam generator(s) to assure adequate removal of reactor decay heat are nqt well defined or documented.
We require that you provide the following AFWS flow design basis infor-mation as applicable to the design basis transients and accident con-ditions for your plant.
l.
a.
Identify the plant transient and accident conditions considered in establishing AFWS flow requirements, including the following events:
1)
Loss of Main Feed (LMFW) 2)
LMFW w/loss of offsite AC power 3)
LMFW w/loss of onsite and offsite AC power 4)
Plant cooldown 5)
Turbine trip with and without bypass 6)
Main steam isolation valve closure 7)
Main feed line break 8)
Main steam line break 9)
Small break LOCA 10)
Other transient or accident conditions not listed above Describe the plant protection acceptance criteria and corres-oonding technical bases used for each initiating event identi-fied above.
The acceptance criteria should address plant limits such as:
- Maximum RCS pressure (PORV or safety valve actuation)
Fuel temperature or damage limits (DNB, PCT, maximum fuel central temperature)
- RCS.cooling rate limit to avoid excessive coolant shrinkage
- Minimum steam generator level to assure sufficient steam generator heat transfer surface to remove decay heat and/or cool down the primary system.
2.
Describe'he analyses and assumptions and corresponding technical justification used with plant condition considered fn l.a.
above including:
a.
Maximum reactor power (including instrument error allowance) at the time of the initiating transient or accident.
b.
Time delay from initiating event to reactor trip.
c.
Plant parameter(s) which initiates AFMS flow and time delay between initiating event and introduction of AR5 flow into steam generator(s).
d.
Minimum steam generator water level when initiating event occurs.
e.
Initial steam generator water inventory and depletion rate before and after AFMS flow comnences - identify reactor decay heat rate used.
f.
llaximum pressure at which steam is released fr om steam generator(s) and against which the AFIt'ump must develop su ficicnt head.
g.
Minimum number of steam generators that must receive AFM flow; e.g.
1 out of 2?,
2 out of 4?
h.
RC flow condition - continued operation of RC pumps or natural circulation.
Maximum AFM inlet temperature.
Following a postulated steam or feed line break, time delay assumed to isolate break and direct AFM flow to intact steam generator(s}.
AFM pump flow capacity allowance to accommodate the time delay and maintain minimum steam generator water level.
Also identify credit taken fox primary, system heat, removal due to blowdown.
k.
Volume and maximum temperature of water in main feed lines between steam generator(s) and AFMS connection to main feed line.
l.
Operating condition of steam generator normal blowdown following initiating event.
m.
primary and secondary system water and metal sensible heat used for cooldown and AFM flow sizing.
n.
Time at hot standby and time to cooldown RCS to RHR system cut in temperature to size AFM water source inventory.
4 3.
Verify that the AFM pumps in your plant will supply the necessary flow to the steam generator(s) as determined by items l and 2
above considering a single failure.
Identify the margin in sizing the pump flow to allow for pump recirculation flow, seal leakage and pump wear.