ML20199G652
| ML20199G652 | |
| Person / Time | |
|---|---|
| Site: | 05200003 |
| Issue date: | 11/19/1997 |
| From: | Mcintyre B WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| To: | Quay T NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NSD-NRC-97-5441, NUDOCS 9711250234 | |
| Download: ML20199G652 (16) | |
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Westinghouse Energy Systems g g) p,,,,,g 3,33 Electric Corporation DCP/NRCI140 NSD NRC-97 5441 DocLet No.: 52 003 November 19,1997 Document Control Desk U.S. Nuclear Regulatory Commission Washington DC 20555 ATIENTION: T. R. Quay i
'l SUlijECT:
RESPONSES TO l'OLLOWON QUES 110NS REGARDING Tile AP600 INSPECTIONS, TESTS, ANAINSES, AND ACCEPTANCE CRITERIA (ITAAC)
Dear Mr. Quay:
Enclosed are three copies of the Westinghouse response to RAI 640.101 on Revision 3 of the AP600 Certified Design Material as requested in a letter from the staff dated September 16,1997. 'lhls response provides a consistent approach to verification of valve response times, including containment isolation valve opening times, in the ITAAC. ADS minimum valve flow areas are addressed in the response to RAI 640.103, previously submitted to the staffin our letter DCI'/NRCll35 dated t
Nos ember 13, 1997.
This submittal closes, frorn Westinghouse' perspective, open item 5855. As a result, the Westinghouse status column will be changeJ to " Closed" in the Open item Tracking System (OITS). The NRC should review this response and inform Westinghouse of the status of this open item to be designated in the "NRC Status" column of the OITS.
Please contact Mr. Eugene J. Piplica at (412) 374 5310 if you have any questions concerning this transmittal, bn f h I
ilrian A. McIntyre, Manager
, Advanced Plant Safety and Licensing closure
- .50011 9N cc:
J. M. Sebrosky, NRC (w/ Enclosure)
J. N. Wilson, NRC (w/ Enclosure)
- N. J. Liparuto, Westinghouse (w/o Enclosure) kE 3!
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0 RESPONSES TO NRC REQUEST FOR ADDITIONAL INFORMATION
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Ouestion RAI (40.101 Important parameters, such as valve opening times assumed in the accident analyses, should be veri 6ed by the ITAAC. His is a generic comment that applies to ITAAC. All valve opening times and ADS minimum valve flow areas specified in SSAR Tables 15.0-4b and 15.6.511 should be veriGed by ITAAC.
Response
Remotely operated valves with safety related functions to transfer open or closed were reviewed to determine if their opening / closing times should be included to the ITAAC. The ITAAC selection criteria in SSAR subsection 14.3.2.1 were used in this review. One of these selection criteria relates to the inclusion of a valve response time in the ITAACs:
Are there any features of functions that have a signincant impact on the safety and operation of the plant.
De Ap600 uses star.dard valve response times unless the safety analysis identifies a requirement for a faster valve. Valves that are required to respond faster tuan the standard valves have a significant impact on the safety of t..e plant because their response is limiting in the analysis. Valves that use standard response times do not have a signincant impact on the safety of the plant because their response is not limiting. In addition, standard valve response times are relatively slow; typically their maximum times are 20 seconds for air operated valves and 30 seconds or more for motor operated valves. Standard valve response times also have signincant margin between their nominal response time and their maximum response time, typically 5 to 10 seconds. nis margin is signincantly greater than that prosided for fast operating valves and as a result, they arc very likely to ope < ate -
within t e required time. Valves with special fast required response times should be included in the ITAACi h
because they satisfy the first criteria listed above. Valves included in the ITAACs will also be included in the Technical Specifications Attached is a table which lists the valves contained in SSAR tables 15.0-4b and 15.6311 as well as containment isolation valves. The valves are listed in this table according to their required response time, nis table shows the required response time and also whether the valve response time is a Technical Specification surveillance.
As a result of this review, the following changes will be made:
(1) The main feedwat:r isolation and control valves and the main steam isolation valves response times will be added to the ITAACs. Tech. Spec. surveillance on valve response times already exist for the main feedwater isolation and control vahes and the main steam isolation valves.
(2) The CVS makeup isolation vahes response times will be added to the ITAACs and the Tech. Spec, surveillances.
(3) ne containment pune isolation valve response time will be increased from 5 seconds to 20 seconds. He existing ITAACs and Tech. Spec. suncillances on all containment isolation valves will be removed.
640.101 1 3 Westingh00S8 1
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RESPONSES TO NRC REQUEST FOR ADDITIONAL INFORMATION 11e main feedwater irolation and control valves, the main steam isolation salves and the CVS makeup isolation valves response times are be added to the ITAAC's because these valves have fast response times.
Note that the attached table includes containment isolation vahes which are not included in SSAR Table 15.0-4b.
As discussed above, the containment purge isolation valve response time will be mercased from 5 seconds to 20 seconds.1he slower response time will result in less wear on the valve which will me.ke the salve more reliable and less likely to leak.1he slower time will not affect the LOCA dose calculation because acthity release from the reactor coolant does not begin for at least 20 seconds after a containment isolation signal is generated. in addition, core damage with its much larger vource term does not occur until much later.
Attached are revised portions of the SSAR and the ITAAC's which show the changes discussed above.
The ADS stage 4 vahe areas are discussed in the response to RAI 640.103.
SSAR Revisens.
SSAR Table 15.0-4b Delay Times For Equipment in Safety Analysis SSAR Section 6.2.3.4.1 Containment isolation Description SSAR Tech Spec 3.6.3 Containment isolation Tech Spec Surveillance SSAR Tech Spec tiases 3.6.30 Containment isolation Tech Spec Dases SSAR Tech Spec 3.4.17 CVS Makeup Isolation Tech Spec
- SSAR Tech Spec tlases 3.4.1711 CVS Makeup Isolation Bases ITAAC Revisons:
- ITAAC Table 2.2.4 4 SGS Tests ITAAC Table 2.2.13 Containment isolation Vahe Response Time Test ITAAC Table 2.3.2-4 CVS Makeup Line Isolation Vahe Response Time Test 640.101 2 Westlflgt100S6
RESPONSES TO NRC REQUEST FOR ADDITIONAL !NFORMATION A
l Valves Listed In SSAR Table 15.0-4b and 15.6.5-1I Valve Size / Type Safety Response Tiene Tech.
ITAAC Fumetion Maximimus Req.
Spec.(4)
I.
Main Steam Line Isol. Valve 32" hydraulic close 5 sec yes yes 2.
Main Feedwater Isol. Valve 16" hydraulic close 5 sec (I) yes yes 3.
Main Feedwater Centrol Valve 16" AOV close 5 sec (1) 3es yes l
4.
CVS Makeup Line Isol. Valve 3" MOV close 10 see yes 3es l
S.
VFS Containment Purge Isol. Valve 16" AOV close 20 sec (2) no (2) no (2) 6.
PRilR liX Control Valve 10* AOV open 20 see no no 7.
CMT Isol. Valve 8" AOV open 20 see no no 8.
CVS Demineralized Water Isol. Valve 3" AOV close 20 sec no no 4"
MOV open 30 see no no 9.
ADS Stage 1 Control Valvo
- 10. ADS Stage 4 Control Valves 10" squib open 30 sec no no II. Steam Generator PORV Block Valve 6" MOV close 44 sec no no
- 12. Containment Isolation Valves (3)
(3) AOV/MOV close 60 see no (3) no (3) 80 sec no no 8" MOV open
- 13. ADS Stage 2/3 Control Valves l
Notes:SSAR Table 15.0-4b currently indicates 10 seconds for this valve. He SSAR table will be revised to indicate that 5 seconds is used in (1) mass / energy cakulations.
SSAR Table 15.0-4b does not include diese vahes. Rese valves connect to containment atmosphere. Hey are currently required to (2) close in 5 seconds, however that time will be changed to 20 seconds. Deir response time will be removed from the Tech. Spec. and the ITAAC.
SSAR Table 15.0 4b does not include these valves. Rese valves do not connect to containment atmosphere; offsite dose calculations are (3) not sensitive to their response time. Heir response time will be removed from the Tech. Spec and the ITAAC's.
Indicates when the valve response time is included in Technical Specification surveillance.
(4) 640.101-3
[ Mil @l0LIS8 1
s RESPONSES TO NRC REQUEST FOR ADDITIONAL INFORMATION Resisions to SSAR Table 15.0-4b Table 15.0-4b LIMITING DELAY TIMES FOR EQUIPMENT ASSUMED IN ACCIDENT ANALYSES Time Delays Component (seconds)
Feedwater isoletion valve closure, feedwater control valve 10 (malmum valuefor non LOCA) closure, or f' edwater pump trip 5 (malmum returfor masvenergy) e Steamline isolation valve closure 5
Core makeup tank discharge valve opening time 20 (maximum) 10 (nominal value for best estimate LOCA) 40 seconds (small break LOCA value; follows a 20-second interval of no valve movement)
Chemical and volume control system isolation valve closure 10 PRilR discharge valve opening time 20 (maximum) 10 (nominal value for best-estimate LOCA) 1.0 second (small-break LOCA value:
follows a 20 second interval of no valve movement)
Demineralized water transfer and storage system isolation 20 valve closure time Steam generator power operated relief valve block valve 44 closure Automatic depressurization system (ADS) valve opening times See Table 15.6.5 11 640.101-4 T Westinghouse 4
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HESPONSES TO NRC REQUEST FOR ADDITIONAL. lNFORMATION s an
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Changes te SSAR Subsection 6.2.3.4.1, Containment Isolatiou System Description One locked-closed isolation valve inside and one automatic isolation valve outside ccatainment. (A
- imple check valve is not used as the automatic isolation valve outside containment )
One automatic isolanot valve inside and one automatic isolation valve outside containmc.a.t. (A simple check valve is tot used as the automatic isolation valve outside containment).
Isolation valves outside containment are located as close to the containment as practical. Upon loss of actuat'ag power, air operated automatic isolation valves fr.il 6losed.
E.
Each hne penetrating the containment t1 u is neither part of the reactor exe.t pressure boundary not connected directly to the containment atmosphere, r.nd that satisfies the requirements of a closed system, has at least one containment isolation valve. This containment isolation valve ' ither automatic, lockedalosea, or capable of remote-manual operation. The valve i* ~
4.tiirment and located e
- aatomatic isolation as close to the containment as practical. A simple check valve '
valve. This design is in compliance with General Design Crit-F.
The containment isolation system is designed according to seis
, megory I requirements s specified in Section 3.2. The components (and supporting structures) of any system, equipment, or structure that are non-seismic and whose collapse could result in loss of a required function of the containment isolation system through either impact or r:sultant flooding are evaluated to confirm that they will rot collapse when subjected to seismic loading resulting from a safe shutdown earthquake.
Air cperated isolation valves fail in the closed position upon loss of ;ir or power. Containment isolation system valves required to be operated after a design basis accident or safe shutdown earthqde are powered by the Class IE de electric power system.
6.2.3.4 Tests and Inspections 6.2.J.4.1 Preoperational Testing Preoperational ti sting is described in Chapter 14. The containment isolation system is testable through the operational sequen:e that is postulate 1 to take place following an accident, including operation of typticable portions of tbc protection system and the transfer between normal and standby power sources.
The safety related function of containr ent boundary integrity is verified by an integrated leakage ra test. The integrated leakage rate is verified to be less than L, as defined in Table 6.131. The integrated containment leakege rate system is utilized to measure the containment leak rate for determination of the integrated leakage rate. The containment isolation valves are verified to close idin ! ::: nt '- $: :::::1.- :-:,=i;; i :icten a _ - _, m. _. t r__ _ n
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640.101-5 W W85tiflgh00S6
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RESPONSES TO NRC REQUEST FOR ADDITIONAL INFORMATION i
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Changes to SSAP Subsection 16.1, Containment Isolation System Tech. Spec. (3.6.3)
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY EP 2.E.2.4
'!crify the icc12tien ti=c cf each pc".- cy In-accordanse spesc.ted and each nutcratic centeir~:ent wit!' the icc12 tier '/21'/c ic *-fithin limite.
Ince r'/i ce T2 ting Pregi2-l SR 3.6.3.4 Verify each automatic containment In accordance isolation valve that is not locked, with the saaled or otherwise secured in position, Inservice m an Testing act uates to the isolation positior actual or simulated actuation si, Program 640.10 ; G W Westinghouse
e RESPONSES TO NRC REQUEST FCR ADb.TIONAL INFORMATl*N t
t Changes to SSAR Subsection 16.1, Containment isolation System Tuh. Spec. Bases (3.6.3B)
BASES BACKGROUND C20tainment Air Filtration System (16-inchi ource valves (continued)
The Contair. ment Air Filtration System operates to:
3 a.
Supply outside air into the containment for ventilation and cooling or heating, b.
Reduce th0 concentration of noble gases within containment prior to and during personnel access, and c.
Equalize internal and external pressures.
Since the valves used in the Containment Air Filtration System are designed to meet the requirements for automatic containment isolution valves, these valves may be opened as needed in MODES 1,
2, 3 and 4.
APELICABLE The containment isolation valve LCO was derived from SAFETY ANALYSES the assumptions related to minimizing the loss of reactor coolant inventory and establishing the containment boundary during major accidents.
As part of the conta'.sment boundary, containment isolation valve OPERABILITY supports leak tightness of the containment.
Therefore, the safety analysis of any event requiring isolation of containment is applicable to this LCO.
The DBA that results in the largest release of radioa-ctive material within containment is a loss of coolant accident (LOCA)
(r,,f. 2).
In the LOCA analyses, it is assumed that containment isolation valves are either closed or f*tnction to close within the required isolation time following event initiation.
This ensures that potential paths to the environment through containment isolation valves (including containment purge valves) are minimized.
The LOCA dose analysis assumes that, folleving containment isolation signal generation, the containment purge isolation valves are closed within
&& 20 seconds.
The remainder of tha automatic isolation valves are assumed closed and the containment leakage is termit sted except for the design leakage rate, L..
Sines the containment isolation valves (continued)
T Westingtiouse
o RESPONSES TO N'.C REQUEST FOR ADDITIONAL INFORMATION l
New SSAR Material In 16.1, CVS Makeup Isolation Tech. Spec. (3.4.17) 3.4 REACTOR COOLANT SYSTEM (RCS) 3.4.17 Chemical and Volume Control System (CVS) Makeup Isolation Valves LCO 3.4.17 Two CVS Makeup Isolation Valves shall be OPERABLE.
APPLICABILITY:
MODES 1, 2,
3, and 4.
ACTIONS CONDITION REQUIRED ACTION COMPLETION T7ME A.
One CVS mTkeup A.1 Restore two CVS-makeip 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> isolation valve isolation valves to inoperable.
OPERABLE status.
B.
Required Action and
NOTE-------------
associated Completion Flow path (s) may be unisolated Time of Condition not intennittently under met.
administrative controls.
2B B.1 Isolate the flow path I hour Two CVS makeup from the CVS makeup isolation valves pumps to the Reactor inoperable.
Coolant System by use of at least one closed manual or one closed and de-activated automatic valve.
- ' O.101-8 T Westinghouse
b RESPONSES TO NRC REQUEST FOR ADDITIENAL INFORMATION I
'8 SURVEILLANCE REQUIR?MENTS SURVEILLANCE FREQUENCY SR 3.1.9.1 Verify two CVS makeap isolation In accordance valves are OPERABLE by stroking the with the valve closed.
Inservice Testing Program SR 3.1.9.2 Verify closure time of each CVS In accordance makeup isolation valve is s10 with the seconds on a actual or simulated Inservice actuation signal.
Testing Program e
640.101-9
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CVS Icolction Valvac B 3.1.9 l
New SSAR Material In 16.1, CVS Makeup Isolation Tech. Spec. Bases (3.4.178)
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B 3.4
- REACTOR dOOLANT SYSTEM (RCS) 3.4.17 Chemifal and Volume Control System (CVS) Makeup Isolation valves BASES BACKGROUND One of the principle functions of the CVC system is to maintain the reactor coolant inventory by providing water makeup for reactor coolant system (RCS) leakage, shrinkage of the reactor coolant during cooldowns, and RCS boron concentration changes.
In the automatic makeup mode of operation, the pressurizer water level starts and stops CV3 makeup to the RCS.
Although the CVS is not considered a safety related system, certain isolation functions of the system are concidered rafety related functien3.
The appropriate isolation valves have been classified and designed as safety related.
One of the safety related functions provided by the CVS is che termination of RCS makeup to prevent over filling of the pressurizer during non-LOCA transients or to prevent steam generator over filling during a steam generator tube rupture.
The CVS makeup line containment isolation valves provide this RCS makeup isolation function.
APPLICABLE One of the initial assumptions in the analysis of SAFETY ANALYSES several non-LOCA events and during a steam generator tube rupture accident is that excessive CVS makeup to the RCS may aggravate the consequences of the accident.
The need to isolate the CVS makeup to the RCS is detected by the pressurizer level instruments or the steam generator narrow range level instruments.
These instruments will supply a signal to the makeup line containment isolation valves in the CVS causing these valves to close and terminate RCS makeup.
Thus the CVS makeup isolation valves are components which function to mitigate an accident.
CVS isolation valves satisfy Criterion 3 of the NRC Policy Statement.
(continuedT
)AP600 B 3.1-10 08/97 Amendment 0 AP01uechsoee16030109 r07111797
CVS Icolction Valvas i
B 3.1.9 BASES (continued)
LCO The requirement that at least two CVS makeup isolation valves be OPERABLE assures that there will be redundant means available to terminate CVS makeup to the RCS during a non-LOCA event or a steam generatcr tube rupture accident should that become necessary.
APPLICABILITY The requirement that at least two CVS makeup isolation valves be OPERABLE is applicable in MODES 1, 2,
3, and 4 with the normal residuni heat removal system (RNS) suction to the RCS not open because a pressurizer overfill event oc steam generator tube rupture accident is considered possible in these MODES, and the automatic closure of these valves is assumed in the safety analysis.
In the applicable MODES, the need to isolate the CVS makeup to the RCS is detected by the pressurizcr level instruments (high 1 setpoint coincident with safeguards actuation or high 2 setpoint) or the steam generator narrow range level instruments (high 2 setpoint).
This isolation function is not required in NODE 4 with the RNS suction open to the RCS or in lower MODES.
In such MODES, pressurizer or steam generator overfill are prevented by the RNS suction relief valve, b
ACTIONS M
If only one CVS makeup isolation valve is OPERALLE, the second valve must be restored to OPERABLE status in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The allowed Completion Time assures expeditious action will be taken, and is acceptable because the safety function of automatically isolating RCS makeup can be accomplished by the redundant isolation valve.
M If the Required Actions and associated Completion Time of Condition A are not met, or if both CVS makeup isolation valves are not OPERABLE (i.e., not able to be cloced automatically), then the makeup flow path to the RCS must be isolated.
Isolation can be accomplished by manually closing the CVS makeup isolation MOVs or alternatively, manual valve (s) in the makeup line between the makeup pumps and the RCS.
(continued)
AP600 B 3.1-11 08/97 Amendment 0
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CVS IOoletion Valvas B 3.1.9
.BApES ACTIONS
. 321 (continued)
The Action is modified by a Note allowing the flow path to be unisolated intermittently under administrative controls.
These administrative controls consist of stationing a dedicated operator at the valve controls, who is in continuous communication with the main control room.
In this way, the flow path can be rapidly isolated when a need for isolation is indicated.
SURVEILLANCE SR 3.1.9.1 REQUIREMENTS Veritication that the RCS makeup isolation vsives are OPERABLE, by stroking each valve cl'osed, demon,strates that the valves can perform their safety related function.
The Frequency is in accordance with the Inservice Testing Program.
SR 3.1.9.2 Verificatior. that the RCS makeup isolation valves closure times are less than that assumed in the safety analysis, is performed by measuti g the time required for each valve to close.
The Frequency is in accordance with the Inservice Testing Program.
REFERENCES 1.
AP600 SGAR Chapter 15, ' Accident Analysis."
AP600 B 3.1-12 08/97 Amendment 0 AP01stechspect160Mios r07-111797
j' RESPONSES TO NRC REQUEST FOR ADDITIONAL INFORMATION
,.,i Changes to SGS ITAAC. Table 2.2.4-4, item 8.h Table 2.2.4-4 (cont.)
Inspections, Tests, Analyses, and Acceptance Criteria Design Commitment Inspections, Tests, Analyses Acceptance Criteria l
8.b) During des l4n basis events, i) Testing will be performed to i) See item 011 in this table, the SOS in conjunct;on with confirm isolation of the main associated portions of the main feedwater, startup feedwater, steam system, feedwater system, blowdown, and main steam lines.
l and the main turbine system See item 011 in this tabic.
limits steam generator blowdown and feedwater 110w to the steam ii) Testing w!il be performed to
- 11) A report exists and generator.
demonstrate that the teruolely concludes that these valves close -
operated Main Steam Line within 5 seconds after receipt of isolation, Main Feedwater a actuation signal.
Isolation and Main Feedwater Control valves close rapidly.
640.101-13
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[1 RESPONSES TO NRC REQUEST FOR ADDITIONAL INFORMATION l@
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Changes to Contafament System ITAAC, Table 2.2.1-3, Item 8 Table 2.2.13 (cort.)
Inspections, Tests, Analyses, and Acceptance Criteria Design Commitment inspections, Tests, Analyses Acceptance Criteria
- 8. The CNS provides the i) A containment integr:ted leak rate i) The leakage rate from safety-related function '
test will be performed.
containment for the integrated leak containment isolation 5 rate test is less than L,.
containment boundary integrity and provides a barrier against
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II) Testing will be performed to ll) See item i1.
demonstrate that remotely operated containment holation valves close.
640.101 14 W Westinghouse
e RESPONSES TO NRC REQUEST FOR ADDITIONAL INFORMATION i
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Changes to Chemical and Volume Control System ITAAC, Table 2.3.2-4, item 8.c.
Table 2.3.2-4 Inspections, Tests, Analyse:, and Acceptance Criteria Design Commitment inspections, Tests, Analyses Acceptance Criteria 8.c) The CVS p;ovides isolation i) See item lib in this table.
i) See item lib in this table, of makeup to the RCS.
II) Testing will be performed to ll) A report extts and concludes demonstrate that the remotely that these valves close within operated CVS makeup line 10 seconds after receipt of a containment isolation valves actuation sig.' sal close rapidly.
i 640.101-15
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