ML19341D277
| ML19341D277 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek, Callaway  |
| Issue date: | 02/18/1981 |
| From: | Dromerick A Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8103050270 | |
| Download: ML19341D277 (55) | |
Text
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Q MQy UNITED STATES y
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NUCLEAR REGULATORY COMMISSION 3
o WASHINGTON, D. C. 20665 p
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FEB 181981
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Docket Nos.: STS 50-482 and/STN 50-483
_ APPLICANTS:
Union Electric Company
/
Kansas Gas and Electric Company FACILTIES:
Callaway Plant, Unit 1 Wolf Creek Generating Station, Unit 1 SUfEARY OF MEETING HELD ON FEBRUARY 12, 1981 WITH CALLAWAY AND WOLF CREEK APPLICANTS A meeting was held on February 12, 1981 at the Bechtel Offices in Gaithersburg, Maryland with representatives of the Union Electric Company, Kansas Gas and Electric Company, SNUPPS Organization and Bechtel. The purpose of the meeting was to discuss matters related to the Auxiliary Feedwater System for the Callaway and Wolf Creek facilities. The list of attendeas is attached as Enclosure 1.
The significant points discussed are summarized as follows:
1.
The applicants presented a detailed description of the Auxiliary Feedwater (AFW) System. The discussion included (1) compliance to NRC criteria, (2) design changes and TMI issues, (3) hazards analysis, (4) design and licensing issues, (5) operaiion of the system and (6) a reliability stwJy. Details of these discussions are presented in.
2.
As a result of these discussions we requested that the applicants provide additional information related to the following:
(a) A discussion and verification that the automatic transfer of auxiliary feedwater suction supply from the condensate storage tank to the essential service water system can occur fast enough to prevent damage to the AFW pumps in the event the common suction supply valve is inadver-i tently closed or blocked. This concern relates to Recommendation GL-2 of NUREG-0611.
(b) A discussion of all items in the March 10, 1980 letter point-by-point including the generic short and long term concerns of NUREG-0611.
(c) A discussion on potential adverse thermal effects on the main feed-water piping when cold auxiliary feedwater is injected into the main feedwater line. The discussion should evaluate the effects with the main feedwater line full and empty. We note that the feedwater check valve is a substantial distance upstream of the main feedwater regulating valve.
(d) An analysis of the potential adverse consequences to safety related equipment from missile generation or room pressurization resulting from rupture of the nitrogen storage tanks located in the auxiliary building.
810sosoHo.
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. 3.
We advised the applicants that we will provide them with information con-cerning our requirements related to (a) steam genera +or/feedwater water hamer test, (b) requirements and clarification concerning the AFW auto-matic initiation and flow indication, (c) acceptability of providing a single tap on the condensate storage tank for the redundant level indica-tion and alarm arrangement and (d) our requirements regarding the 48-hour AFW pump endurance tests.
4.
The appplicants advised that they will provide the information requested in the near future.
l hhWGYC A. Dromerick, Project Mar sger Licensing Branch No. 1 Division of Licensing cc : See next page r
e b
fir. J. K. Gryan Vice President - Nuclear Union Electric Company P. 0.' Box 149 St. Louis, Missouri 63166 cc: Mr. Nicholas A. Petrick Mr. William Hansen Executive Director - SHUPPS 5 Choke Cherry Road Resident Insocctor/Callaway UPS c/o USMRC Rockville, Maryland 20850 Steednan, Missouri 65077 Gerald Charnof f, Esq.
Shaw, Pittr:an, Potts &
Trowbridge 1800 M Street, N. W.
Washington, D. C.
20036 Mr. J. E. Birk Assistant to the General Counsel Union Electric Company P. O. Box 149 St. Louis, Missouri 63166 D r. Vern Starks Route 1, Box 863 Ketchikan, Alaska 99901 Ms. TrevaHearn, Assistant General Counsel Missouri Public Service Commission P. O. Box 360 Jefferson City, Missouri 65102 M r. D. F. Schnell Manager-Nuclear Engineering Union Electric Company P. U. Box 149 St. Louis, Missouri 63166
n iT,(&
Y Mr. Glenn L. Koester i
Vice President - Nuclear Kansas Gas and Electric Company 201 North Market Street P. O. Box 208 Wichita, Kansas 67201 cc: Mr. Nicholas A. Petrick Ralph Foster, Esq.
Executive Director, SNUPPS Kansas Gas & Electric Company 5 Choke Cherry Road P. O. Box 208 Rockville, Maryland 20750 Wichita, Kansas 67201 Mr. Jay Silberg, Esquire William H. Ward, Esq.
Shaw, Pittman, Potts & Trowbridge MACEA 1800 M Street, N. W.
5130 Mission Road Washington, D. C.
20036 Shawnee. Mission, Kansas 66205 Mr. Donald T. McPhee
.Ms. Treva Hearne, Assistant General Counsi Vice Presidnet - Production Public Service Commission Kansas City Power and Light Company P. O. Box 360 1330 Baltimore Avenue Jefferson City, Missouri P. O. Box 679 Kansas City, Missouri 64101 Mr Tom Vandel Resident Inspector / Wolf Creek NPS James T. Wiglesworth, Esq.
c/o USNRC 9800 Metcalf P. O. Box 1407 Suite 400 Emporia, Kansas 66801 General Souare Center Overland Park, Kansas 66212 Mr. Michael C. Keener Wolf Creek Project Director Mr. William H. Griffin, Esq.
State Corporation Commission Assistant Attorney General State of Kansas State of Kansas Fourth Floor, State Office Bldg.
State House Topeka, Kansas 66612 Topeka, Kansas 66612 Mr. John M. Wylie, II Energy Reporter Kansas City Star 1729 Grand Kansas City, Missouri 64108 Mr. Gary Haden Wichita Eagle and Beacon Box A,-20 Wichita, Kansas 67201
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o-7 MEETitiG
SUMMARY
DISTRIBUTION Docket File G. Lear flRC POR V. Noonan Local POR FEB ]g ;gg S. Pawlicki TIC /flSIC/ Tera V. Benaroya NRR Reading Z. Rosztoczy LB#1 Reading W. Haass H. Denton D. Muller E. Case R. Ballard D. Eisenhut W. Regan R. Purple D. Ross p
B. J. Youngblood P. Check
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A. Schwencer R. Satterfield 2s G
F. Miraglia
- 0. Parr J. Miller p
p F. Rosa B
79 W. Kreger
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G. Lainas 4
W. Butler R. Vollmer g
A J. P. Knight R. Houston g%
R. Bosnak T. Murphy F. Schauer L. Rubenstein 47
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R. E. Jackson T. Speis M
Project Manager A. Dromerick W. Johnston Attorney, OELD J. Stolz M. Rushbrook S. Hanauer OIE (3)
W. Gammill ACRS (16)
T, Murley R. Tedesco F. Schroeder N. Hughes D. Skovholt M. Ernst NRC
Participants:
R. Baer C. Berlinger K. Kniel G. Knighton A. Thadani D. Tondi J, Kramer D, Vassallo P, Collins D. Ziemann bcc: Applicant & Service List
Meeting - February 12, 1981 l
Callaway Plant i
Wolf Creek Station l
Attendance List NAME ORGANIZATION A. Dromerick NRC - DL R. Stark NRC - DL E. Sullivan NRC - DSI J. N. Ridgely NRC - DSI T. L. Chan NRC - DSI J. O. Cermak SNUPPS M. R. Goodman Bechtel - SNUPPS D. Egan Bechtel - SNUPPS (startup)
W. L. Luce Westinghouse - Licensing F. X. Thomson Westinghouse - Nuclear Safety N. P. Adel Bechtel - SNUPPS A. Hassan Bechtel - SNUPPS Herman La Gous NRC - Consultant Melvin L. Johnson KG & E David M. Pepe YAEC (Seabrook)
Harry W. Majors Southern Company Services Inc. (Vogtle)
James A. Zell KG & E R. P. Wendling Union Electric Co. Nuc. Eng.
Michael D. Hall KG & E S. R. Blazo Bechtel - Nuclear Staff J. S. Prebula Bechtel - SNUPPS i
Tony Diperna Bechtel SNUPPS Cont. Sys.
G. P. Rathbun KG & E l
J. M. McKinstray KG & E Frank Schwoerer SNUPPS A. C. Passwater Union Electric R. L. Stright SNUPPS C. H. Scheilbrellmt ANL/NRC J. S. Wermiel NRC/NRR/fSI/ASB
- 0. D. Parr NRC/NRR/USI/ASB Paul Natick Bechtel Chick Herbst Bechtel
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4-4
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NRC - SNUPPS MEETING j
AUXILIARY FEEDWATER SYSTEM February 12, 1981 AGENDA
'l INTRODUCTION Bob Stright i
i j
GENERAL DESCRIPTION OF SYSTEM Frank Schwoerer 4
I COMPLIANCE TO NRC CRITERIA Paul Nastick
- Break i
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DESIGN CHANGES AND 11 ISSUES s-Tony DiPerna a
j HAZARDS ANALYSES Chuck Herbst i
- Lunch -
DESIGN, LICENSING ISSUES Al Passwater OPERATION OF THE SYSTEM Jim McKinstray
.i 3
- Break -
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RELIABILITY STUDY Don Ashton/ Steve Blazo CONCLUSIONS, PLANS Bob Stright
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1 AUXILIARY FEEDWATE SYSTD4 DESCRIPTION A.
GENERAL 1.
Safety-related system 2.
Also used during normal operating situations (startup, cooldown, etc.)
3 Safety-related operation is automatic, except for manual throttling.
4.
Operatio" under normal situations is manual.
5 Can be operated from Aux. Shutdown lanel.
M-02AL01 B.
SOURCE OF WATER 1.
Normally the CST (450,000 gal)
-Not seismically designed
-Not tornado protected 2.
Safety-related (backup) source is ESW System.
-Auto switchover on 2/3 low pump suction pressure
-Two independent trains (Sep. grps. 1 & 4)
-Each supplies 1 MD pump & TD pump C.
PUMPS 1.
2 Motor-driven (AC pwr, Sep grps 1 & 4) 2.
1 Turbine-driven (DC control, Sep grp 2)
M-02A302
-Steam supply from 2 steam lines M-02FCO2
-Steam supply valves DC pwrd (Sep grp 2)
-Pump & turbine lube oil cooling by pumped water flow 3
Pump type: Ingersoll Rand HMTA
-MD:
500 g;m (net)
-TD: 1000 gym (net) 4.
Pumps start automatically on AFAS
- a. MD pumps
-2/4 low-low level in any 1 SG
-trip of both main feedwater pumps
-SIS
-loss of offsite power
- b. TD pump
-2/4 low-low level in any 2 SG
-loss of offsite power s_-
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D.
INJECTION FLOW PATHS m
1.
Aux FW syst discharges into 4 feedwater lines, just outside containment.
2.
3 TD pump supplies 4 BG.
4 Dischg throttling valves on MD, pumps are AC powered, modulating valves. Sep grps 1 & 4; same sep grp as pump. Valven are manually controlled, except as noted below. Have position indication on main control board and on ESF status panel.
5 Disch throttling valves on TD pump are DC solenoid controlled, air operated valves. Sep grps 1 5 4.
Valves are manually controlled.
Position indication on MCB and iSF status panel.
6.
Dischg lines from TD pump orificed to ensure delivery of adequate flow to operable SGs with steamline or feedline break.
7 Dischg lines from MD pump similarly orificed, but later analyses of secondary breaks showed short-time potential for pump runout /
cavitation. Therefore have added auto throttling of FD pump dischg to limit MD pump flow.
C E.
LOCATICN & Ph7CICAL ARRA':GJE:T M-0GO:6 1.
At groun ' level in Aux. Eldg.
2.
Beneath F3, MFW lines & protected from them by concrete floor slab.
M-6G022 3
sa, pump in a separate compartment.
4.
Valves in separate compts.
5 Waterproof doors for flood protection 6.
Leakage drains to sump. Operation of sump pump annunciated on MC3; also logged on 30F computer.
F.
DYNAMIC EFFECTS /WATR HAK4ZR M-02AE02 1.
2.
SG/ feedwater line features
-J-tubes on feedring
-Welded thermal sleeve
-Limited horizontal length of feedwater line at SG nozzle j
b I
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SNUPPS AUXILIARY FEEDWATER SYSTEM
~
REVIEW MEETING FSAR
References:
Overall Compliance with 10CFR50 A pp. A " General Design Criteria" Section 3.1.3 Conformance to NRC Regulatory Guides Appendix 3A Reg. Guide 1. 26, Rev. 3 Table 3.2-4 Reg. Guide 1.29, Rev. 3 Table 3.2-3 Reg. Guide 1.62, Rev. O Table 7.1-5 Reg. Guide 1.102, Rev. 1 Section 3.4 Reg. Guide 1.117, Rev. 1 Section 3.3 Conformance to NRC Branch Technical Positions BTP ASB 3-1 Table 3.6-2 BTP MEB 3-1 Table 3.6-2 BTP ASB 10-1 Section 10.4.9 V
~
SNUPPS P1 ping and Instrument Diagrams M-02 AB02 (Main Steam System )
Fig. 10.3-1 tt-02 AE02 (Feedwater System)
Fig. 10.4-6 M-02 AL01 ( Auxiliary Feedwater System)
Fig. 10.4-9 M-02 AP01 (Condensate Storage /Transf er System)
Fig. 9.2-12 M-02EF01 (Essential Service Water System)
Fig. 9.2-2 M-02EF02 (Essential Service Water System)
Fig. 9.2-2 M-U2 EF01 (Essential Service Water System)
Fig. 9.2-2 (Callaway Site Addendum)
M-K2EF01 (Essential Service Water System)
Fig. 9.2-2 (Wolf Creek Site Addendum)
M-02 FCO2 ( Auxiliary Tue51ne System)
Fig. 10.4-10 SNUPPS Equipment Location Drawings M-0G022 ( Auxiliary Bldg. El. 2000 ')
Fig. 1.2-11 M-0G026 (Auxiliary Bldg. - Section A)
Fig. 1.2-15 i _-
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SNUPPS
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10.4.9 AUXILIARY FEEDWATER SYSTEM The auxiliary feedwater system (AFS) is a reliable source of water for the steam generators.
The AFS, in conjunction with safety valves in the main steam lines, is a safety-related system, the function of which is to remove thermal energy from the reactor coolant system by releasing second-ary steam to the atmosphere.
The AFS also provides emergency water following a secondary side line rupture.
Removal of heat in this manner prevents the reactor coolant pressure from increasing and causing release of reactor coolant through the pressurizer relief and/or safety valves.
The auxiliary feedwater system may also be used following a reactor shutdown in conjunction with the condenser dump valves or atmospheric relief valves, to cool the reactor coolant system to 350 F and 400 psig, at which temperature the residual heat removal system is brought into operation.
The motor-driven auxiliary feedwater pumps and the auxiliary feedwater system are also used during plant startups to supply water from the condensate storage tank to the steam generators, until steam is available to drive the steam generator feedwater pump turbines.
10.4.9.1 Design Bases
)
10.4.9.1.1 Safety Design Bases SAFETY DESIGN BASIS ONE - The AFS is protected from the effects of natural phenomena, such as earthquakes, tornadoes, hurricanes, floods, and external missiles (GDC-2).
SAFETY DESIGN BASIS TWO - The AFS is designed to remain functional after an SSE or to perform its intended function following a postulated hazard, such as a fire, internal missile, or pipe break (GDC-3 and 4).
SAFETY DESIGN BASIS THREE - The safety funtions can be performed, assuming a single active component failure coin-cident with the loss of offsite power.
The system require-ments may be met with a complete loss of ac power (CDC-34).
SAFETY DESIGN BASIS FOUR - The AFS is designed so that the
~
active components are capable of being tested during plant operation.
Provisions are made to allow for inservice inspection of components at appropriate times specified in the ASME Boiler and Pressure Vessel Code,Section XI.
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10.4-46
e.
SNUPPS
\\
SAFETY DESIGN BASIS FIVE - The AFS is designed and fabricated consistent with the quality group classification assigned by Regulatory Guide 1.26 and the seismic category assigned by Regulatory Guide 1.29.
The power supply and control functions are in accordance with Regulatory Guide 1.32.
SAFETY DESIGN BASIS SIX - The AFS, in conjunction with the con-densate storage tank (nonsafety-related) or essential service water system, provides feedwater to maintain sufficient steam generator level to ensure neat removal from the reactor coolant system in order to achieve a safe shutdown following a main feedwater line break, a main steamline break, or an abnormal plant situation requiring shutdown.
The auxiliary feedwater N/'
system is capable of delivering full flow P ir i rirrte M lub after detection of any accident requiring auxiliary feedwater (refer to Chapter 15.0).
SAFETY DESIGN BASIS SEVEN - The capability to isolate com-ponents or piping is provided, if required, so that the AFS safety function will not be compromised.
This includes isolation of components to deal with leakage or malfunctions and to isolate portions of the system that may be direct-ing flow to a broken secondary side loop.
SAFETY DESIGN BASIS EIGHT - The AFS has the capacity to be operated locally as an alternate, redundant means of feedwater control, in the unlikely event that the control room must be evacuated.
10.4.9.1.2 Power Generation Design Bases POWER GENERATION DESIGN BASIS ONE - The.%FS serves as a means of supplying feedwater for normal plant startup and shutdown.
10.4.9.2
System Description
10.4.9.2.1 General Description The system consists of two motor-driven pumps, one steam turbine-driven pump, and associate piping, valves, instru-ments, and controls, es shown on Figure 10.4-9 and described in Table 10.4-12.
Figure 10.4-10 shows the piping and instru-mentation for the steam turbine.
Each motor-driven auxiliary feedwater pump will supply 100 percent of the feedwater flow required for removal of decay heat from the reactor.
The turbine-driven pump is sized to supply up to twice the capacity of a motcr-driven pump.
This capacity is sufficient to remove decay heat and to
[
provide adequate feedwater for cooldown of the reactor coolant system at 50 F/hr within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of a reactor trip s,,
from full power.
10.4-47
SNUPPS Normal flow is from the condensate storage tank (CST)
}
to the auxiliary feedwater pumps.
Two redundant safety-related back-up sources of water from the essential service water system (ESWS) are provided for the pumps.
For a more detailed description of the automatic sequence of events, refer to Section 10.4.9.2.3.
The condensate storage tank capacity allows the plant to remain at hot standby for 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and then cool down the primary system at an average rate of 50 F per hour to a temperature of 350 F.
Figure 10.4-11 provides the required makeup rate to the steam generators to maintain their level based on removing decay heat from a fully irradiated reactor core.
Initially, sensible heat is removed from the reactor coolant system to reduce the temperature from a full-power operation average temperature of 588 F to a nominal hot shutdown tempera-ture of 500 F.
Subsequently, to bring the reactor down to 350 F at 50 F/hr, an initial makeup rate of 500 gpm is required.
Refer to Section 9.2.6 for a description of the condensate storage system.
In order to remove decay heat by the steam generators, auxiliary feedwater must be supplied to the steam generators in the event that the normal source of feedwater is lost.
The minimum required flow rate is 470 gpm.
)
v Provisions are incorporated in the AFS design to allow for periodic operation to demonstrate performance and struc-tural and leaktight integrity.
Leak detection is provided by visual examination and in the floor drain system described in Section 9.3.3.
10.4.9.2.2 Component Description Codes and standards applicable to the AFS are listed in Tables 3.2-1 and 10.4-12.
The AFS is designed and con-structed in accordance with quality groups B and C and seismic Category I requirements.
MOTOR-DRIVEN PUMPS - Two auxiliary feedwater pumps are drive, by ac-powered electric motors supplied with power from indepen-dent Class IE switchgear busses.
Each horizontal centrifugal pump takes suction from the condensate storage tank, or alternatively, from the ESWS.
Pump design capacity includes continuous minimum flow recirculation, which is controlled by restriction orifices.
TURBINE-DRIVEN PUMP - A turbine-driven pump provides sys-tem redundancy of auxiliary feedwater supply and diversity of motive pumping power. The pump is a horizontal centrifugal y
v 10.4-48
.m SNUPPS f.
unit.
Pump bearings are cooled by the pumped fluid.
('
Pump design capacity includes continuous minimum flow recirculation.
Power for all controls, valve operators, and other' support systems is independent of ac power sources.
Steam supply piping to the turbine driver is taken from two of the four main steam lines between the containment penetrations and the main steam isolation valves.
Each of the steam supply lines to the turbine is equipped with a locked-open gate valve, normally closed air-operated globe valve with air-operated globe bypass to keep the line warm, and two nonreturn valves.
Air-operated globe valves are equipped with de-powered solenoid valves.
These steam sup-4 ply lines join to form a header which leads to the turbine through a normally closed, de motor-operated mechanical trip and throttle valve.
The main steam system is described in Section 10.3.
The steam lines contain provisions to prevent the accumu-lation of condensate.
The turbine driver can operate with steam inlet pressures ranging from 100 to 1,250 psia.
Ex-haust steam from the turbine driver is vented to the at-mosphere above the auxiliary building roof.
PIPING AND VALVES - All piping in the AFS is seamless car-(s_,
bon steel.
Welded joints are used throughout the system, except for flanged connections at the pumps.
The piping from the ESWS to the suction of each of the auxiliary feedwater pumps is equipped with a motor-operated butterfly valve, an isolation valve, and a nonreturn valve.
Each line from the condensate storage tank is equipped with a motor-operated gate valve and a nonreturn valve.
Each motor-driven pump discharges through a nonreturn valve and a locked-open isolation valve to feed two steam generators through individual sets of a locked open isolation valve, a normally open, motor-operated control valve, a check valve followed by a flow restriction orifice, and a locked-open globe valve.
The turbine-driven purp discharges through a nonreturn valve, a locked-open gate valve to each of the four steam generators through individual sets of a locked-open isolation valve, a normally open air-operated control valve, followed by a nonreturn valve, a flow restriction orifice, and a locked-open globe valve.
The turbine-driven pump discharge control valves are air operated with de-powered solenoid valves.
At each connection to the four main feedwater lines, the auxiliary feedwater lines are equipped with check valves.
The system design precludes the occurrence of water hammer in k'3_,
the main feedwater inlet to the steam generators.
For a de-scription of prevention of water hammer, refer to Section 10.4.7.2.1.
10.4-49
-a
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SNUPPS
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10.4.9.2.3 System Operation PLANT STARTUP - During startup, the auxiliary feedwater pumps and control valves are used under manual control to supply feedwater from the condensate storage tank to the steam generators until sufficient steam is available to operate the turbine-driven main feedwater pumps.
NORMAL PLANT OPERATION - The AFS is not required during normal power generation.
The pumps are placed in the auto-matic mode, lined up with the condensate storage tank, and are available if needed.
NORMAL PLANT COOLDOWN - During cooldown, the auxiliary feed-water pumps and control valves are used under remote manual control to supply watcr from the condensate storage tank to the steam generators.
Auxiliary feedwater flow to each steam generator is regulated by the control valves.
Steam generated in this manner is bypassed to the main condenser.
The auxiliary feedwater pumps are used until reactor coolant temperature drops to 350 F, at which point the residual heat removal system is placed in service and further cools down the reactor.
EMERGENCY OPERATION - In addition to remote manual-actuation capabilities, the AFS is aligned to be placed into service
,)
s_,
automatically in the event of an emergency.
Anyone of the
~
following conditions will cause automatic startup of both motor-driven pumps:
a.
Two out of 4beee low-low level signals in any one steam generator b.
Trip of both main feedwater pumps c.
Safeguards sequence signal (initiated by safety injection signal) d.
Class IE bus loss of voltage sequence signal The turbine-driven pump is actuated automatically 'on either of the following signals.
a.
Two out of t-hece low-low level signals in any two steam generators dou /E L. bf &y A"j"w A4pd In the case of failure of the water supply from the conden-sate storage tank, the normally closed, motor-operated butterfly valves from the ESWS are automatically opened on low suction header pressure.
)
m 10.4-50
l SNUPPS
(
If a motor-driven pump supplying two of the three intact steam generators fails to function, the turbine-driven pump will automatically start when a low-low level is reached in two of the four steam generators.
'k
[ C Low pump diGeharge pressure alarms will alert the operator jCNSNgy :
to a secondary side break.
The operator will then determine
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which loop is broken by observing high auxiliary feedwater C Nc, Gk!s, flow, using control room flow indication, and c.use rA.a.
appropriate discharge control valve.
This can be accomplished within 10 minutes after pump start.
Refer to Chapter 15.0.
10.4.9 Safety Evaluation Safety evaluations are numbered to correspond to the safety design bases in Section 10.4.9.1.1.
SAFETY EVALUATION ONE - The AFS is located in the auxiliary building.
This building is designed to withstand the effects of earthquakes, tornadoes, hurricanes, floods, external mis-siles, and other appropriate natural phenomena.
Sections 3.3, 3.4, 3.5, 3.7(B), and 3.8 provide the bases far the adequacy of the structural design of the auxiliary building.
p SAFETY EVALUATION TWO - The AFS is designed to remain func-tional after a SSE.
Sections 3.7(B).2 and 3.9(B) provide the design loading conditions that were considered.
Sections 3.5, 3.6, and 9.5.1 provide the hazards analyses to assure that a safe shutdown, as outlined in Section 7.4, can be achieved and maintained.
For a more complete description of motor qualification, refer to Sections 3.10(B) and 3.11(B).
SAFETY EVALUATION THREE - Complete redundancy is provided and, as indicated by Table 10.4-13, no single failure will compromise the system's safety functions.
All vital power can be supplied from either onsite or offsite power systems, as described in Chapter 8.0.
The turbine-driven pump is energized by steam drawn from two main steam lines between the containment penetrations and the main steam isolation valves.
All valves and controls necessary for the function of the turbine-driven pump are energized by the class IE de power supplies.
Turbine bearing lube oil is circulated by an integral shaft-driven pump.
Turbine and pump bearing oil is cooled by pumped auxiliary feedwater.
SAFETY EVALUATION FOUR - The AFS is initially tested with the program given in Chapter 14.0.
Periodic operational I \\_.
testing is done in accordance with Section 10.4.9.4.
Section 6.6 provides the ASME Boiler and Pressure Vessel Code,Section XI requirements that are appropriate for the AFS.
10.4-51
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SNUPPS SAFETY EVALUATION FIVE - Section 3.2 delineates the quality
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group classification and seismic category applicable to this system and supporting systems.
Table 10.4-12 shows that the components meet the design and fabrication codes given in Section 3.2.
All the power supplies and control function necescary for safe furl: tion of the AFS are Class IE, as described in Chapters 7.0 and 8.0.
1 SAFETY EVALUATION SIX'- The AFS provides a means of pumping Q
sufficient feedwater to prevent damage to the reactor follow-ing a main feedwater line break inside the containment, or a main steamline break incident, as well as to cool down the reactor coolant system at a rate of 50 F per hour to a tempera-ture of 350 F, at which point the residual heat removal system
'N can operate.
Pump capacities, as shown in Table 10.4-12, y
and start times are such that these objectives are met.
(k Restriction orifices located in the pump discharge linest g g imit the flow to the broken loop so that adequate coolcown flow s
-N (470 gpm) can be provided to the other steam generators for s
NQ E removal of reactor decay heat and so that containment design
{1 pressure is not exceeded.
Pump discharge head is suffi-V g \\s cient to establish the minimum necessary flowrate against
}p a steam generator pressure corresponding to the lowest pres-y sure setpoint of the main steam safety valves.
The maximum
.v 1
time period required to start the electric motors and the steam turbine which drive the auxiliary feedwater pumps is T
y chosen so that sufficient flowrates are established within
/
minut: :f ::tucti:n of :::::icted prete: tion 1:gic.
Refer 3
SAFETY ALUATION i - As di cussed in Sections 10.4.9.2 and 10.4.9.5 and Chapter 15.0, adequate instrumentation and control
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capability is provided to permit the plant operator to quickly
'},
identify and isolate the auxiliary feedwater flow to a broken secondary side loop.
Isolation from nonse.fety-related portions of the system, including the condensate storage tank, is pro-vided as described in Section 10.4.9.2.
SAFETY EVALUATION EIGHT - The AFS can be controlled from either the main control room or the auxiliary shutdown panel.
Refer to Section 7.4 for the control descriptior..
10.4.9.4 Tests and Inspections Preoperational testing is described in Chapter 14.0.
The per-formance and structural and leaktight integrity of system _om-ponents is demonstrated by periodic operation.
The AFS is testable through the full operational sequence that brings the system into operation for reactor shutdown and for DBA, including operation of applicable portions of the pro-tection system and the transfer between normal and standby
)
power sources.
10.4-52
SNUPPS The safety-related components, i.e.,
pumps, valves, piping, and turbine, are designed and located to permit preservice and inservice inspection.
10.4.9.5 Instrumentation Applications The AFS instrumentation is designed to facilitate automatic operation and remote control of the system and to provide continuous indication of system parameters.
Pressure transmitters are provided in the discharge and suction lines of the auxiliary feedwater pumps.
Auxiliary feedwater flow is '
' c_ated by Elt: flow indicators provided in the control room.
~ ach steam generat.or)
If the condensate supply from the storage tank fails, the resulting reduction of pressure at the pump suction is indicated in the control room.
Flow transmitters and control valves with remote control stations are provided on the auxiliary feedwater lines to each steam generator to indicate and allow control of flow at the auxiliary shutdown panel and in the control room.
Table 10.4-14 summarizes AFS controls, alarms, indication of status, etc.
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TABLE 10.4-12 AUXILIARY FEEDWATER SYSTEM COMPONENT DATA Motor-Driven Auxiliary Feedwater Pump (per pump)
Quantity 2
Type Horizontal centrifugal, multistage, split case with packing Capacity, gpm (each) 575 TDH, ft 3,200 NPSH required, ft 17 NPSH available, ft (min) 28 Material Case Alloy steel Impellers Stainless steel Shaft Stainless steel Design code ASME Section III, Class 3 Seismic design Category I Driver
)*
v Type Electric motor Horsepower, hp 800 Rpm 3,560 Power supply 4,
160 V, 60 Hz, 3-phase Class 1E Design code NEMA Seismic design Category I Turbine-Driven Auxiliar2 Feeccater Pump Quantity 1
Type Horizontal centrifugal, multistage, split case with packing Capacity, gpm 1,145 TDH, ft 3,450 NPSH required, ft 17 NPSH available ft (min) 28 Material Case Alloy steel Impellers stainless steel Shaft Stainless steel
)
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SNUPPS TABLE 10.4-12 (Sheet 2)
Design code ASME Section III, Class 3 Driver Type Noncondensing, single stage, mechanical-drive steam turbine Rpm 3,850 Horsepower, hp 1,590 Design code NEMA Seismic design Category I Motor-Driven Pump Control Valves Quantity 4 (2 per pump)
Type Motor-operated globe valve Size, in.
4 C
50 Design pressure, psig 1,800 Design temperature, F 150 Material Carbon steel Design Code ASME Section III
(--
Seismic Design Category I Turbine-Driven Pump Control Valves Quantity 4
Type Air-operated globe valve Size, in.
4 C
50 Design pressure, psig 2,000 Design temperature, F 150 Material Carbon steel Design Code ASME Section III Seismic Design Category I (v
t
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TABLE 10.4-13 l
AUXILIARY FEEDWATER SYSTEM SINGLE ACTIVE FAILURE ANALYSIS Component Failute Comments Suction isolation In the event that the CST is un-Redundant nonreturn check.
va'.ves from CST available, valve fails to close valve is provided, and suffi-upon receipt of automatic isola-cient ESW flow is provided to tion signal or loss of power the auxiliary feedwater pumps Suction isola-In the event that the CST is un-Two 100-percent redundant tion valves from available, valve fails to open upon backup ESW trains are pro-ESW receipt of automatic signal or loss vided.
Operation of one train of power of the suction valves meet the requirements.
9 Suction header Loss of one transmitter.
No pro-2-out-of-3 logic reverts to
{
pressure trans-tection logic generated 1-out-of-2 logic, and protec-i citters tion logic is generated by I
other devices i
Motor-driven auxi-Fails to start on automatic signal Two motor-driven pumps are
.l.
licry feedwater provided.
One pump is suf-pump ficient to meet decay heat removal requirements.
If due to a main steam or feed-water line break, the oper-ating motor-driven pump can-not supply two intact steam generators, the turbine-driven pump will supply feedwater I
to meet decay heat removal requirements.
Turbine-driven Fails to open on automatic signal Parallel connections are pro-purp steam supply vided on two main steam lines.
valve from main One of the two valves will steam header supply 100 percent of the g
turbine steam requirements.
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t SNUPPS TABLE 10.4-13 (Sheet 2)
Corponent Failure Comments Turbine-driven Failure resulting in loss of func-Two motor-driven pumps are pump tion provided.
Either will pro-vide 100 percent of the feed-water requirements.
Motor-driven pump Failure resulting in loss of flow The second motor-driven pump control valve or loss of flow control will provide 100 percent of the required flow through e'
separate control valves.
I If due to a main steam or
- l feedwater line break, the operational motor-driven pump i.
train cannot supply two intact j) steam generators, the tur-bine-driven pump will sup-ply feedwater to meet decay I
heat removal requirements.
l,-
Failure to close valve in line feed-Second motor-driven
,l ing broken loop pump will provide 100 per-cent required flow through i
separate control valves.
E Turbine-driven Failure resulting in loss of flow Either of the two motor-dri-
[
pump control valve or loss of flow control ven pumps will supply 100 percent of the required feed-l,!
water flow through separate gj control valves.
1 Failure to close valve inline feed-Either of the two motor-1 ing broken loop driven pumps will supply 100 percent required flow through I;
separate control valves.
y,
1 SNUPPS
~.
TABLE 10.4-14 AUXILIARY FEEDWATER SYSTEM INDICATING, ALARM, AND CONTROL DEVICES I1) Control Room Indicatic,n/ Control Control Room Local Alarm Condensate storage tank suction valve position X
X ESW suction valve position X
X Condensate storage tank suction header pressure X
Low pump suction pressure X
X X
Low pump discharge pressure X
X X
Pump flow control valve operation X
X Pump flow control valve g
s--
position X
X Auxiliary feedwater flow X
X Auxiliary feedwater pump turbine trip & throttle valve position X
X Auxiliary feedwater pump turbine speed X
X Auxiliary feedwater pump turbine low lube oil pressure X
Auxiliary feedwater pump turbine high lube oil temperature X
(1) Local control here means the auxiliary shutdown panel.
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800 700 R ATED CONDITIONS:
3425 MWE NSSS POWER 1000 psia SG STE AM PRESSURE SG SECONDARY SIDE TEMPER ATURE 5570 F @ 0 2 HRS.
600 3270 F @ 7 HRS.
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O 1
2 3
4 5
6 7
TIME AFTER REACTOR TRIP, HRS.
SNU PPS FIGURE 10.411
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SNUPPS element, a nower-coerated main feedwater isolation valve 3
(MFIV),Ca f'ree-swinging check valve an auxiliary feedwater
/
connection, Anth a chemical injecuon connection,4~udJ The condensate and feedwater chemical injection system, as shown in Figure 10.4-7, is provided to inject hydrazine and ammonia into the condensate pump discharge downstream of the condensate demineralizers and additional hydrazine and ammonia into the four main feedwater lines connecting with the four steam generators.
Injection points are shown in Figure 10.4-6.
During normal power operation, the continuous addition of hydrazine and ammonia to the condensate system is under automatic control, with manual control optional.
As dis-cussed in Section 10.3.5, the addition of ammonia and hy-drazine estab? '-'es the design pH according to the conden-sate and fee system chemistry requirements and estab-lishes a col.
initial hydrazine residual in the feed-
.. c water system so that oxygen inleakage can be scavenged.
The following measures have been taken to protect personnel from any toxic effects of chemicals:
a.
Ammonium hydroxide and hydrazine solution and measuring tanks are provided with a 5-psig nitrogen blanket to minimize ammonia and hydrazine vapors in
)
the general atmosphere of the turbine building.
m_
b.
Concentrated chemicals are diluted to less than a 5-p"rcent solution strength in the solution tanks.
c.
Corrosion-resistant construction materials (stain-less steels) are used throughout the storage and injection equipment.
d.
Chemical mixing is accomplished by closed-loop recirculation with centrifugal recirculation pumps.
No external tank mixers are used to agitate tank contents.
e.
Chemical drum unloading is accomplished with air-driven drum bung pumps, which are nonsparking and pose no electrical hazard to personnel.
The manually controlled feedwater ammonia and hydrazine system is provided for special plant conditions, such as j
hydrostatic test, hot standby, layup, etc.
These conditions require high levels of pH and hydrazine residual to minimize corrosion in the steam generators.
10.4-24
~ ~
~~ -"
~
^~
~
SNUPPS feedwater line and associated branch lines between the con-3 tainment penetration and the torsional restraint upstream
/
of the MFIV are designed to meet the "no break zone" criteria, as described in NRC BTP MEB-3-1 (refer to Section 3.6).
MAIN FEEDWATER ISOLATION VALVT.S - One main feedwater iso-lation valve (MFIV) is installed in each of the four main feedwater lines outside the containment and downstream of the feedwater control valve.
The MFIVs are installed to prevent uncontrolled blowdown from more than one steam generator in the event of a feedwater pipe rupture in the turbine building.
The main feedwater check valve provides backup isolation.
The MFIVs isolate the nonsafety-related portions from the safety-related portions of the system.
In the event of a secondary cycle pipe rupture inside the containment, the MFIV limits the quantity of high energy fluid that enters the containment through the broken loop and provides a pressure boundary for the controlled addition of auxiliary feedwater to the three intact loops.
The valves are bi-directional, double disc, parallel slide gate valves.
Stored energy for closing !c supplied by accumulators which contain a fixed mass of high pressure nitrogen and a vari-able mass of high pressure hydraulic fluid.
For emergency closure, a solenoid is de-energized, which causes the high pressure hydraulic fluid to be admitted to the top of the valve stem driving piston and also causes the fluid stored g
below the piston to be dumped to the fluid reservoir.
Two J
s--
separate pneumatic / hydraulic power trains are provided for each MFIV.
Electrical solenoids are energized from separate Class IE sources.
MAIN FEEDWATER CONTROL VALVES AND CONTROL BYPASS VALVES -
The MF control valves are air-operated angle valves which automatically control feedwater between 20 percent an.d full power.
The bypass control valves are air-operated globe valves, which are used during startup up to 25-percent power.
The MF control valves and bypass control valves are located in the turbine building.
In the event of a secondary cycle pipe rupture inside the containment, the main feedwater control valve (and associated bypass valve) provide a diverse backup to the MFIV to limit the quantity of high energy fluid that enters the containment i
through the broken loop.
For emergency closure, either of two separate solenoids, when de-energized, will result in valve closure.
Electrical solenoids are energized from separate Class IE sources.
MAIN FEEDWATER CHECK VALVES - The main feedwater check valves are located i d iatM y d r.;tre s of-- G.x.in fn d=
2-
n::tr-In the event of a secondary cycle,
alc/A lY "b O
emeb.
10.4-26
~. _
SNUPPS pipe rupture,inside the containment, the main feedwater k
check valves provide a diverse backup to the MFIV to assure the pressur boundary "-
MO the three intact loops.
CHEMICAL ADDITION LINE CHECK VALVES AND ISOLATION VALVES -
The check valves are located downstream of the isolation valves in the chemical addition lines.
The check valves provide a diverse backup to the isolation valves to assure the pressure boundary.
The normally closed isolation valves are air-operated valves which fail closed.
CONDENSATE PUMPS - The three condensate pumps are motor driven and operate in parallel.
Valving is provided to allow individual pumps to be removed from service.
Pump capacity is sufficient to meet full power requirements with two of the three pumps in operation.
LOW-PRESSURE FEEDWATER HEATERS - Parallel strings of closed feedwater heaters are located in the condenser necks.
The No. 1, 2, 3, and 4 heaters have integral drain coolers, and their drains are cascaded to the next lower stage feed-water heater in each case.
The drains from No. I heaters are dumped to the main condenser.
Feedwater leaving the No. 4 heaters is headered and goes to the steam generator feed pumps.
The heater shells are carbon steel, and the
(
tubes are stainless steel.
s-HIGH-PRESSURE FEEDWATER HEATERS - Parallel strings of three high-pressure feedwater heaters with integral drain coolers in heaters 6 and 7 are used.
The No. 7 heaters are drained to the No. 6 heaters which, in turn, drain to the heater drain tank.
The No. 5 heaters drain directly to the heater drain tank.
The heater shells are carbon steel, and the tubes are stainless steel.
Isolation valves and bypasses are provided which allow each string of high-pressure and low-pressure heaters to be removed from service.
System operability is maintained at reduced power in the case of the low-pressure heaters with the parallel heaters and bypass line.
Provisions are made in all heater drain lines, except No.
5, which drains via the heater drain tank, to allow direct discharge to the condenser in the event the normal drain path is blocked.
HEATER DRAIN TANK - A single heater drain tank drains the shells of No. 5 and No. 6 feedwater heaters and provides reservoir capacity for drain pumping.
The heater drain tank is installed in such a way that the No. 5 heaters drain
- (
freely by gravity flow.
The drain level is maintained within the tank by a level controller in conjunction with a heater drain pump.
u 10.4-27
SNUPPS
.r er SAFETY EVALUATION TWO - The safety-related portions of the
}
CFS are designed to remain functional after a SSE.
Sections 3.7(B).2 and.3.9(B) provide the design loading conditions that were considered.
Sections 3.5, 3.6, and 9.5.1 provide the hazards analyses to assure that a safe shutdown, as out-lined in Section 7.4, can be achieved and maintained.
SAFETY EVALUATION THREE - The CFS safety functions are accomplished by redundant means, as indicated by Table 10.4-7.
No single failure will compromise the system's safety functions.
All vital power can be supplied from either onsite or offsite power systems, as described in Chapter 8.0.
SAFETY EVALUATION FOUR - Preoperational testing of the CFS is performed as described in Chapter 14.0.
Periodic inservice functional testing is done in accordance with Section 10.4.7.4.
Section 6.6 provides the ASME Boiler and Pressure Vessel Code Section XI requirements that are appropriate for the CFS.
SAFETY EVALUATION FIVE - Section 3.2 delineates the quality group classification and seismic category applicable to the i
safety-related portion of this system and supporting systems.
Table 10.4-6 shows that the components meet the design and
'S fabrication codes given in Section 3.2.
All the power
- r. # g./
s_,
asdescribedinChapters,/yF)pt supplies and controls necessary for the safety-related functions of the CFS are Class IE,
,p g#
7.0 and 8.0.
SAFETY EVALUATION SIX - Fcr a main feedwater line break p[ pv inside the containment or an MSLB, the MFIVs located in th hat' auxiliary building and the main feedwater control valves V
located in the turbine building are automatically clos 0"
upon receipt of a feedw ter isolation signaled"For ep associated redundant isolation of the chemical addition line p intact 1 cop, the QMdevu2%eod$h MFIV Fand will close, formino a pressure boundary to permit auxiliarv.
_feedwater addition.
The auxiliary feedwater system is described in Section 10.4.9.
SAFETY EVALUATION SEVEN - For a main feedwater line break upstream of the MFIV, the MFIVs are supplied with redundant power supplies and power trains to assure their closure to isolate safety and nonsafety-related portions of the system.
Branch lines downstream of the MFIVs contain normally closed, power-operated valves which close on a feedwater isolation signal.
These valves fail closed on loss of power.
w 1
10.4-30 i
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FIGURE 82.4-1 C
PAGE 8 OF 74 asoset
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PURPOSE TO PERFORM A RELIABILITY ANALYSIS TO DETERMINE THE RELATIVE RELIABILITY OF THE SNUPPS AUXILIARY FEEDWATER SYSTEM (AFWS).
TO FACILITATE A MEANINGFUL COMPARIS0N WITH NRC ANALYSES, THE INITIATING EVENTS GIVEN IN NUREG-0611 WERE USED, AS WELL AS SIMILAR ASSUMPTIONS, RELIABILITY DATA, AND EVALUATION TECHNIQUES.
TO IDENTIFY THE DOMINANT FAILURE MODES OF THE SNUPPS AFWS.
TO EXAMINE IN MORE DETAIL THAN TREATED IN NUREG-0611, THE POSSIBLE CONTRIBUTIONS OF SINGLE POINT VULNERABILITIES, COMMON CAUSES, HUMAN ERROR, AND TEST / MAINTENANCE OUTAGES TO AFWS UNAVAILABILITY.
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SCOPE THREE INITIATING EVENT SCENARIOS WERE ANALYZED:
CASE 1: LOSS OF MAIN FEEDWATER (LMFW)
CASE 2: LOSS OF MAIN FEEDWATER COINCIDENT WITH LOSS OF 0FFSITE POWER (LMFW/ LOOP)
CASE 3: LOSS OF MAIN FEEDWATER COINCIDENT WITH LOSS OF ALL A.C.
POWER (LMFW/LOAC)
THE EXISTENCE OF THE AB0VE SCENARIOS WAS CONSIDERED A PRIORI AND AN EVALUATION OF THEIR PROBABILITY OF OCCURRENCE WAS CONSIDERED TO BE OUTSIDE THE BOUNDS OF THIS STUDY.
BROAD OR RELATIVELY RARE COMMON CAUSE FACTORS SUCH AS FLOOD, FIRE, EARTHOUAKE, SAB0TAGE OR HIGH ENERGY LINE BREAKS WERE NOT CON-SIDERED.
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TECHNICAL SYSTEM t
TASK P&lD'S NUREG'061 '
i SPECIFICATION DESCRIPTIONS I
I I
I SYSTEM BOUNDS FAULT TREE TASK 2 DEVELOPMENT TASK 3 MINIMAL CUT SETS 1
STATISTICAL INDEPENDENT HA A
A A ION, TASK 4 T+M, AND HUMAN ERROR QUANTIFICATION IMPORTANCE TASK 5 EVALUATION I
COMMON CAUSE HARDWARE 10PERATOR ACTION TASK 6 T+M, AND HUMAN ERROR OUANTIFICATION I
RESULTS TASK 7 CONCLUSIONS
-.4
MAJOR ASSUMPTIONS MISSION SUCCESS CRITERIA A MINIMUM WATER FLOW 0F 470 GPM MUST BE DELIVERED WITHIN ONE MINUTE TO AT LEAST TWO STEAM GENERATORS FOLLOWING A LOSS OF MAIN FEEDWATER.
DC AND BATTERY BACKED AC POWER AVAILABLE WITH A PROBABILITY OF o
1.0.
FOR THE BASE CASE, ONE DIESEL GENERATOR IS ASSUMED AVAILsBLE o
WITH A PROBABILITY OF 1.0, AND THE SECOND DIESEL GENERATOR FAILS WITH A PROBABILITY OF.04/ DEMAND.
AN ACTUATION FAILURE PROBABILITY OF 7 x 10 3 PER TRAIN WAS IN-o CLUDED IN THE EVENTS REPRESENTING THE FAILURE OF THE MDPs AND TDP.
TEST AND MAINTENANCE OUTAGES WERE CONSISTENT WITH THE o
STANDARD TECHNICAL SPECIFICATION.
ASSUMPTIONS REGARDING COMPONENT STATUS (0N/0FF),
PARTIAL-o CAPACITY PERFORMANCE, AND TIME-DEPENDENT (DELAYED) FAILURES ARE MADE CONSERVATIVELY. THAT IS, COMPONENTS ARE ASSUMED OFF, TO HAVE ZERO FLOW AND TO FAIL IMMEDIATELY.
NO TREATMENT OF PIPE BREAKS IN THE AFW SYSTEM. HOWEVER, DURING o
THE SENSITIVITY PHASE OF THE STUDY, THE IMPACTS OF PIPE BREAKS IN NON SEISMICIN0N 0 INTERFACING SYSTEMS WERE EXAMINED.
HUMAN ERROR TREATMENT (0PTIONS A,8 AND C)
OPTION A: THESE PROBABILITIES CONTAIN NO EXPLICIT HUMAN ERROR, l.E., THE FAILURES ARE STRICTLY HARDWARE FAILURES.
OPTION B: THESE PROBABILITIES INCLUDE HUMAN ERROR FOR FAILURE TO POSITION MANUAL AND MOV VALVES PROPERLY; THIS OPTION ASSUMES DOUBLE CHECK AND WALK-AROUND PROCEDURES FOR MANUAL VALVES. NOTE:
THIS APPLIES ONLY TO THE LOCKED OPENED VALVES IN THE AFWS FLOW PATH (l.E., FROM WATER SUPPLY TO STEAM GENERATORS).
OPTION C: THIS OPTION IS SIMILAR TO OPTION B EXCEPT THAT NO VALVE POSITION CHECKING IS ASSUMED AND, THEREFORE, A HIGHER HUMAN ERROR PROBABILITY IS ASSIGNED.
NOTE: ALL HUMAN ERROR PROBABILITIES ARE TAKEN FROM NUREG 0611, TABLE lll-2.
ALSO, NO CREDIT WAS TAKEN FOR POSITIVE OPERATOR ACTION AFTER INITIATION OF THE ACCIDENT.
l
TABLEE 2*
BASIC DATA USED FOR PURPOSEE OF CONDUCTING A COMPARAT1VE ASSESSMENT OF EXISTING AFWS DESIGNS & THElR POTENTIAL RELIABILITIES POINT VALUE ESTNATE OF PROBABILITv 0F
- FAILUAE ON DEY AND 1.
COMPONENT (H A ADW ARE) F AILUAE D ATA
- 3. VALVES MANUAL VALVES (PLUGGED)
- 1 x 10-d CHECK VALVES
- 1 x 10 d MOTOR OPERATED VALVES
- MECHAN! CAL COMPONENTS
-1x10 3
- PLUGGlNG CONTRIBUTION
- 1 x 10 d
- CONTROL CRCUli(LOCAL TO VALVE)
Wl0UARTERLY TESTS
- 6 x 10 3 WIMONTHLY TESTS
-2x10 3 PtSTON ACTUATEDVALVES
- A0V-MECHANICAL COMPONENTS
- 3 x 10 4
- SOV MECHANICAL COMPONENTS
- 1 x 10 3
- CONTROL CIRCUIT (NOTE.USE MOV 6"
FA! LURE R ATE IF V ALVE IS NOT Fall SAFE)
- b. PUMPS:(1 PUMP)
- MECHANICAL COMPONENTS
- 1 x 10 3
APPLIES TO ELECTRICAL PUMdn Wl0VARTERLY TESTS
- 7 x 10 3 WIMONTHLY TESTS
-4x10 3
- c. ACTUATION LOGIC (ASSUMES AT LEAST 3
10F 2 LOGIC)
- 7 x 10 ma,n t.l
' ERROR F ACTORS OF 310 (UP AND DOWN) ABOUT SUCH VAGd!S AAE NOT UNEXPECTED FOR BA$lC OATA UNCERTAINTIES
" 6 REPRESENTS A NUMBER SO SMALL IN MAGN TUDE THAT IT MAY BE NEGLECTED FOR BASIS OF THIS STUDY
- TABLE lli 2 WAS TAKEN FROM NUREG-0611. FOR SOME ITEMS NOT INCLUDED IN THIS TABLE. THE LERs AND WASH 1400 WERE USED AS REFERENCES.
u
e f
TABLE 5 2 (CONTINUED) 11 TEST & MAINTEN ANCE OUTAGE CONTRIBUTIONS a CALCULATIONAL APPROACH
- 1. TEST OUTAGE OTEST. ( s hrsitest)( s testst ear) f
- hrs / year
- 2. Maint enance Octage O AINT.
- O 22 (
- hrs!maint. act)
M 720 b.
Data Tables for Test & Ma:nt 0utages
- SUMVARY OF TEST ACT DUR ATION CALCULATED RANGE ON TEST MEANTEST ACT COMPONINT ACT DURATION TIME. HR DUR ATION TIME. tD h' v
PUMPS 025 4 1.4 VALVES 0.25 2 0 86 DIESELS 0.25 4 14 INSTRUMENTATION 0.25 4 14 LOG NORYAL YOCELED MAINTENANCE ACT DURATION RANGE ON MEAN ACT COMPONENT DUR ATION TIME, HR DUR ATION TiVE. MR PUMP $
1/2 24 7
1/2-72 19 VALVES 1/2-24 7
DIESELS 2 72 21 INSTRUVENTATION 1/4 24 6
' NOTE. THESE DATA TABLES WERE TAKEN FROM THE REACTOR SAFETY STUDY (W ASH 1400)(2) FOR puqPOSES 05 THIS AFW SYSTEM ASSESSMENT. WHERE THE PLANT TECHNICAL SPECIFICATIONS PLACED LIVITS CN TnE OUTAGE DURATION (S) ALLOWED FOR AFW SYSTEM TRAINS THIS TECH SPEC LIMIT WAS USED TO ESTiv ATE THE MEAN DURATION TIMES FOR MAINTENANCE ACTS. iN GENERAL. IT WAS FOUND THAT THE CUTAGES ALLOWED FOR MAINTEN ANCE DOM!NATED THOSE CONTRIBUTIONS TO AFW SYSTEM UNAVAILAB:LITY FROY OUT4GES DUE TO TESTING.
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TABLE O 2 (t,uMTMED) i Ill. HUMAN ACTS & ERRORS - FAllORE DATA ESTNATI D HtM AN E RROR/F Aft URE PROBABILITIES MODIF YING FACTORS & SITUATIONS WITH VALVE POSITION WITH LOCAL WAl K AROUND &
NDCATION W CONTROL ROOM DOUBLE CHECK PROCEDURES Wl0 EITHER EST ON EST ON EST ON EAROR ERROR ERROR P0lNT V ALUE EST FACTOR PolNT VALUE EST FACTOR POINT VALUE EST.
FACTOR
- a. ACTS & ERRORS OF A PRE ACCIDENT NATURE
- 1. VALVES MISPOSITIONED DURING TESTIMAINT.
(a) SPECIFC SINGLE VALVE WRONGLY SELECTED 00T OF A POPUL ATlON OF VALVES DURING CONDUCT OF A TEST OR MAINTENANCE ACT (X NO 1 *10 2"1 1 '10 2~1 102~1 0F VALVES M POPUt A190N AT CHOCE) 20 X
20 2
X 10 X
10 (b) NADVERTENTLY LE AVES CORRECT VALVE N WRONG POSITION 5x10 4 20
$x103 go io 2 10
- 2. MORE THAN ONE VALVE IS AFFECTED 1x10 4 20 1x10 3 10 3xto2 go (CDUPLED ERRORS) 3 MISCAllBRAT10N OF SENSORS /ELECTRCAL RELAYS (a) ONE SENSOR / RELAY AFFECTED 5x103 10 102 10 (t,) MORE THAN ONE SENSOR / RELAY AFFECTED 1 x to 3 go 3, 20 3 ic
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STATISTICAL INDEPENDENT HARDWARE, TEST
& MAINTENANCE & OPERATOR ERROR QUANTIFICATION IDENTIFICATION OF DOMINANT MINIMAL CUT SETS 1
MANUAL CALCULATION IMPORTANCE EVALUATION CONSERVATIVE FIRST ORDER APPR0XIMATION FOR THE TOP EVENT PROBABILITY
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1 GENERATION OF MINIMAL CUT SETS A MINIMAL CUT SET IS A GROUP OF HARDWARE /0PERATOR ACTION FAILURE (S)
THAT CAUSE SYSTEM FAILURE.
GENERATE MINIMAL CUT SETS IDENTIFY MINIMAL CUT SETS FOR HARDWARE /0PERATOR t,CTION FAILURES IDENTIFY MINIMAL CUT SETS FOR HUMAN ERROR IDENTIFY MINIMAL CUT SETS FOR TEST AND MAINTENANCE FAILURES
=_
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IMPORTANCE
- '*" - [Pg.(E) yTION A PtT0e) where.
P(TOP) = PROBABILITY OF TOP EVENT,i E.,
(AFWS FAKURE) FCd A PARTCULAR CASEM)Pil0N
[P (E) = SUMMATK)N OF PR00A9tlTIES OF K k
CUT SETS WHCH CONTitBUTE TO THE TOP EVENT AND WHCH CONTAIN THE EVENT E.
CASE 1 ua E
E CASE ?
E E
CASE 3 N/A F
s TEST ACTUATION
" PUMP" F AILURES HUMAN ERROR THROTTLETAVERN081 DIESEL CSi tSOL ATK)N AND FAILURE VALVE GEN (RATOR VALVE MAINTENANCE
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c COMMON CAUSE HARDWARE, TEST &
MAINTENANCE & HUMAN ERROR CALCULATIONS OUALITATIVE IDENTIFY COMMON OR SIMILAR HARDWARE, TEST, MAINTENANCE,
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HUMAN ACTIONS, ETC., BETWEEN REDUNDANT TRAIN (S).
QUANTITATIVE INCORPORATE COMMONALITY FACTORS INTO STATISTICALLY IN-DEPENDENT MODEL TO ESTIMATE THE COMMON CAUSE EFFECT.
l
t LOSS OF MAIN FEEDWATER (WITH OFFSITE POWER AVAllABLE)
THE SYSTEM UNAVAILABILITY DURING THIS TRANSIENT IS DOMINATED BY SEVERAL COMBINATIONS OF THREE EVENT CUT-SETS. THESE INCLUDE:
TEST AND MAINTENANCE HARDWARE FAILURES CST ISOLATION VALVE FAULT COINCIDENT WITH FAILURE OF THE ESWS
FAILURE TYPES TEST AND MAINTENANCE OUTAGES OF THE MOTOR-DRIVEN PUMP AND TURBINE-DRIVEN PUMP ARE BASED ON MONTHLY PUMP TESTS, AS WELL AS, A MEAN MAINTENANCE DURATION BASED ON 72 HOURS OF ALLOWABLE INOPERABILITY. THE HARDWARE FAILURES OF THE MDP TRAIN INCLUDE PUMP FAILURE, IN-LINE VALVE FAILURES AND CONTROL SIGNAL FAILURES TO THE PUMP. ADDITIONALLY, HUMAN ERRORS, WHICH CONSISTED OF FAILURES TO MAINTAIN MANUAL VALVES (IN-LINE)IN AN OPEN POSITION DURING OPERATION, WERE MODELED FOR VARIOUS PROBABILITIES.
NOTE: THE TURBINE-DRIVEN PUMP WAS MODELED IN THE SAME MANNER AS THE MDPs EXCEPT THAT VALVE FAILURES IN THE STEAM SUPPLY LINES WERE INCLUDED IN THE MODEL.
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LOSS OF MAIN FEEDWATER (BUT WITH LOSS OF 0FFSITE AC POWER?
GENERALLY, THE DOMINANT FAILURE CONTRIBUTORS FOR THIS SCENARIO ARE THE SAME AS IN THE PREVIOUS TRANSIENT EXCEPT THAT FAILURE OF A MOTOR-DRIVEN PUMP CAN RESULT FROM THE POTENTIAL FAILURE OF THE ASSOCIATED DIESEL-GENERATOR TRAIN. AS CAN BE SEEN IN FIGURE II, THE RESULTS ARE SENSITIVE TO THE FAILURE PROBABILITIES ASSIGNED TO THE DIESEL GENERATORS.
t' LOSS OF MAIN FEEDWATER (WITH LOSS OF ALL AC POWER)
SINCE IN THIS SCENARIO LOSS OF BOTH OFFSITE AND ONSITE AC POWER IS POSTULATED TO OCCUR, THE AFWS IS REDUCED TO THE SINGLE TURBINE-DRIVEN PUMP TRAIN. THE UNAVAILABILITY OF THE TDP TRAIN IS DOMINATED BY THE FOLLOWING SINGLE EVENTS:
TEST AND MAINTENANCE FAILURE OF THE TDP (INCLUDES ACTUATION FAILURE)
DISCHARGE VALVE LEFT CLOSED (HUMAN ERROR)
CST ISOLATION VALVE LEFT CLOSED (HUMAN ERROR)
FAILURE OF THE STEAM SUPPLY THROTTLE OR SPEED GOVERNOR VALVES
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