ML19312D409
| ML19312D409 | |
| Person / Time | |
|---|---|
| Site: | Rancho Seco |
| Issue date: | 03/12/1980 |
| From: | Walbridge W SACRAMENTO MUNICIPAL UTILITY DISTRICT |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8003240356 | |
| Download: ML19312D409 (7) | |
Text
{{#Wiki_filter:_ _ _ o 4 $. SACRAMENTO MUNICIPAL UTILITY DISTRICT O 6201 S SMUD 95813; (916) 452 3211 March 12, 1980 Mr. Darrell G. Eisenhut, Acting Director Division of Operating Reactors Office of Nuclear Reactor Regulation Nuclear Regulatory Commission Washington, D. C. 20555-Re: Docket No. 50-312 LWR Primary Coolant System Pressure Isolation Valves
Dear Sir:
In response to your letter of' February 23, 1980, regarding LWR Primary Coolant System Isolation Valves: The scenario described in the Event V (see the Reactor Safety Study, WASH-1400) accident is initiated by the failure-of two check valves as a pressure isolation barrier. Further, these fail- ' ures are hypothesized to cause overpressurization and rupture of Low -Pressure Injection System piping which results in a LOCA that bypasses containment. The only areas where an Event V valve configuration exists within high pressure piping connecting the Reactor Coolant System to low pressure system piping at Rancho Seco is shown on Enclosure 1 and is described below.- Low Pressure Injection enters the Containment Building through Penetrations 27 and 28. In each loop, outer containment isolation is provided by a 10" motor-operated gate valve (SFV26005/SFV26006) which is normally closed dur-ing power operation. Piping upstream of this valve has a design pressure / temperature rating of 450 psig/300*F. Low Pressure Injection continues to the Reactor Vessel through 10" penetra-tion piping to a 10" stop theck valve (DHS015/DHS016). The design pressure / temperature rating of this penetration piping is 2500 psig/300*F. Inner con-tainment isolation is provided by the stop check valve which is " locked open" ~during normal operation, but in which the check function prevents high pres-sure reactor coolan*, from overpressurizing the Low Pressure Inj ection piping. Low Pressure Injection piping downstream of the stop check valve also has a design pressure / temperature rating of 2500 psig/300*F and is connected to 14" diameter Core Flood Injection ' piping which as a design pressure / temperature rating of 2500 psig/650*F. Low Pressure Injection / Core Flood Injection en-ters the Reactor Vessel af ter passing through a check valve (RCS001/RCS002). Core Flood Injection leaves the Core Flood Tanks through 14" diameter pipbg Od which has a design pressure and temperature of 700 psig/300*F and reaches a 5 motor-operated gate valve (HV26513 and HV26514), which is normally open dur- /// ing power operation with its breaker racked out. The injection path continuesgge 80032403 56 P, PeM / /
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AN_ ELECTRIC SYSTEM S E R VIN G f.10 R E THAN 600,000 IN THE HEART OF C A LI F O R N I A
et - Pzge-2 through piping.which has a design pressure and temperature rating of 2500 psig/650*F to -a check valve (CFS001/CFS002). The remainder of the Core Flood Injection path piping was described.above with the Low Pressure ' Injection: description. .Continu'aus surveillance of all check valves is being accomplished to assure ReactorLCoolant System integrity. Small-3/4" lines are connected to each Low Pressure Injection line upstream.of the stop check valve..-These lines bypass the stop check valves and are routed to each Core Flood Tank Dis-charge line. Each bypass line is'provided with a stop check valve.(DHS017 and DHS018), a pressure breakdown orifice (F026033 and F026034) and a sim-pie check. valve (DHS067,and DHS068). The bypass ' lines prevent overpressur-ization of the Decay Heat System Injection lines upstream of the Decay Heat System Injection line stop check valves (DHS015 and DHS016) by directing any back. leakage from the Decay Heat -System Injection check valves (RCS001
- and RCS002) and the Decay Heat System Injection stop check valves (DHS015 and DHS016)-to the Core Flood Tanks.
~ Leakage into the' Core Flood Tanks through the -Low Pressure Injection penetra-tion-leakoff lines or directly from Core Flood Injection check valves (CFS001 and CFS002) will cause changes in both Core Flood Tank pressure and level. Any changes in either of these parameters will be noted during daily surveil-lance of selected plant _ instrumentation required by SP 200.02, Instrumentation Surveillance Performed Each Day. - In addition, Core Flood Tank level and pres- ~ sure are both' indicated and annunciated in the Control Room. Annunciator' Pro-cedures for the H2SFA and H2SFB panels stipulate operator action for high Core F1. cod Tank level and pressure, which include determination of the cause of the ab ormal pressure or-level and restoration of pressure or level to normal. A reminder-is given that Core Flood Tank pressure and lefel must be normal for continued plant-operation. The Core Flood Tanks' pressures and volumes are maintained at 600 psig and 1040 cubic ft. respectively. The alarms are set .for'585 psig low, 615 psig high pressure and 1055 cubic feet high, 1025 cubic feet low. These critical limits will detect check valve leakage within a -short time once initiated. None of the Core Flood / Low Pressure Injection . check valves have ever.been known or-found to lack integrity. Upon approval of our IST submittal requests for relief and Amendment 63, Rev. 1,'to our Technical Specifications, periodic surveillance will be insti-tuted to further assureEcheck-valve integrity and availability of the Low Pressure Injection penetration leakoff lines which return to the Core Flood Tanks. Core Flood Injection / Low Pressure Injection check ' valves will be partial or full stroke tested at Cold Shutdown and Refueling. (See pages 4-11 and'12 of the Rancho Seco-Valve Testing Program, attached as Enclosure 2 for clari- -fication of stroking requirements for each valve.) Verification of actual . disc position' before stroking and during plant restart by the procedure shownlas Enclosure 3 will assure that disc movement'actually occurred during fatroking and that each. valve has reseated ~following stroking. If the pres-- sure tests outlined show L he valves to 'beileaking, leakage measurement tests t
- will~ be-performed with' allowable leakage based on the capacities of Core Flood
~ Tank:orLDecay Heat Cooler relief-valves. Verification that the Low Pressure LInjection penetration lenkoff -lines are free and that the check valves 4 p, l --y r y r F
c,. 1.
- z-Pags 3
-(DHS067/DHS068)'and"stop check valves 7(DHS017/DHS018) stroke will be per-formed.each cold shutdown. ~ ' Verification' that' Reactor. Coolant System leakage is within allowable limits is made daily by calculation with data taken-by SP 200.02, and weekly
- byiSP 207.04B,' Weekly Reactor Coolant System Leakage Test.
If leakage in- -creases beyond' Technical; Specification limits by SP 200.02, a calculation of-leakage is:made. utilizing SP-207.04B. Further action taken is based on Technical. Specification, requirements.- -We feel that-the program for periodic' testing and continuous surveillance outlined above will increase plant reliability and safety and that no modi-
- fication to the plant is necessary. Plant. procedures should_be modified to incorporate the requirements outlined 'above.
If you have' any questions or comments, please contact Mr. Ron Colombo at Rancho Seco Nuclear Generating Facility, Route 1, Box 550, Herald, Ca. -95638. . Respectfully submitted, }. / .( . A,,L. Wm. C. Walbridge, s General Manager WCW:WBG: bks Enclosures-L Subscribed and sworn to before me this-12th day of March, 1980. I Notaty Public h 0FFICIAL SEAL -l . l hd. PATRICIA K. GE!SLER l y-sofar eceuc cAuren.w - r P#'NCIP4 cNICE re - SACAAYLNTQ LOUNTY ^ My Cctnmisstori Ea tes &vember 22,1983 l e.............s.................e
ENCLOSURE 1: LOW PRESSURE INJECTION / CORE. FLOOD CONFIGURATION CORE FLOOOLW6 TANK vzes3/s j ggy RCS500(RC5500 Po= 700 PSI G To= 300* F . / l[$ Po=Z500 P516 g o=650*F-T HY26513(HV24Sl4.) CF5508(CF55t \\d k d ' CF55r5(CFS5t'O REALTOR ESEL DRSOb7(DHSO6B [7 N \\l-200 3//,d Kcs001(Rcsooz)s Po = 600 PstG @ CF5001(CF5002) To: 200*F id' d F026033(f02C330% __ DR5015(Ot%0lfo)\\ Po = 2500 PStG To : Soo* F h !M5tDE .A / OOTbtDE DBS0rl(bits 0t8) . 253MES25) N DHSS30(D05524) . SFV26005(sfV2600(,) # 1 ' w ~.. f4 F120H BECAY HEAT REMOVAL Po= 450 PStG COOLER E2(DA(E2606) To-SooE
'4-11'
- Rev.,1 ?
-ENCLOSURE 2 7 Sheet-1"of.: 2
- ASME CODE CLASS. VALVE TESTING REQUIREMENTS +
SYSTEM DECAY ' HEAT / CORE FLOOD VALVE VA M VALVE P&ID/ CATECORY-VALVE VALVE TEST TEST .NO. . COORDINATE A B ClD E ~ E ! L '3ER -DHS059 522/E10 X 11" CK . FST CS PV 7 HV20001 522/D11 X 12" ' GT. M0 FST CS PV 8 T CS VPI -RF' RCS002 522/D9-X 14"' CK P T. CS'&' PV 9-S RF
- CFS002 522/09 X
14" CK PST CS & PV 9 RF DHS016 522/09 X X X 10" ' SCK CS PV 9 FST SLTJ RF PV 38 SP205.02 LLRT VP RF RCS001 522/07 X 14" CK PST CS & PV 9 RF C'FS001 522/D7 X 14" CK PST CS & PV 9 RF DHS015 522/07 X X X 10" SCK FST CS py 9 1
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d = q -j) 3;;_ ; W k y :*: } 3+_, ;;;: -.c w ENCLOSURE 3: g.
- Low Pressure Injection./ Coreflood
- Check / - Stop LCheck -
Valve Disc Position.. Verification With RCS 0'750 psig Installa' pressure gauge on CFS508 (CFS516) and-read pressure. l Pressure is NRCS Pressure is 600 psig & CFT pressure,750 psig, level = constant & CFT level = constant. 1 l CFS001 - (CFS002) ll RCS001 ~- (RCS002) - is closed is closed i Close-HV26513-Close HV26513 .(HV26514)' (HV26514) SFV26005 :(SFV26006). and DHS 017 (DHS018) 'I Insta11' Pressure Gaugo Depressuriz'e Piping
- on CFS513 (CFS517).&
through CFS508 (CFS516) DHS530 (DHSS24) Pressurize Piping through'- Depressurization Depressurization-CFS508.(CFS516)~and' observe Successful Not Successful pressure lon CFSS13 (CFS517) & DHS530 -(DHSS24). RCS001-(RCS002). RCS001 - (RCS002) is closed is open. p -ig. - Pressure remains Pressure > 600 psig _ on. Pressure > 000 psig on - i% 600 psig.&_CFT CFS513 (CFS517) or CFT DHS530 (DHS524): Repair & Reter,t 1". vel = constant Jevel-increasing' i -l l-CFS001;(CFS002) & CFS001 (CFS002)___ DHS015 (DHS016) DHS015 (DHS106). is open
- is open cro-closed.
o g Repair.& . Repair & Retest. Retest .a 4-. 4 E 1 9 n e- = =v-}}