ML19219B292
| ML19219B292 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 02/28/1981 |
| From: | Epps R LAWRENCE LIVERMORE NATIONAL LABORATORY |
| To: | |
| Shared Package | |
| ML19219B289 | List: |
| References | |
| NUDOCS 8103110840 | |
| Download: ML19219B292 (16) | |
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TEChhlCAL EVALUATION OF THE SUSCEPiiEltITY OF SAFETY-REL ATED S)LTEMS TO FLOODIho CAUSED EY THE F AILURE OF h0h-CATEGOPY I SYSTEMS FOR THE M IhE YANKEE ATOMIC POWER STATI0h Docket ho. 50-309 by Richarc C. Epps Februar; 1981 huclear Systems Safety Progran, Lawrence Livermore Naticnal Lcboratory Liser wre, Calif c nis 8103110 ryo
AE STR ACT This repcrt occu~.erits the technic al es abatier, cf the.cire iankee Ator1c F wer S t a t i c r..
Tne rurpost of this a aluatior, res
- 1. cetermine nnetter the failure of any non-Class I (selsnic) equipment cc,1c result in a conditicn, such as flooding, that mignt aaversely af ect the pcricrmar.ce cf the s af ety-relutu. cquipment reCuired f or the s af t shutconn of tne f ac ~ lity,
or to mitigate the consecuences Lf an accicent.
Crit (ria otselcpec by the U.S. Nuclear Regulatory Corrission were uset to evaluate the acceptatilitj cf the e>1 sting protection system as well as rieas ures taken by Maine Yankee Atomic Power Conpany (MYAPC) to minirize the aanger of ficocing anc to protect saf ety-related equipment.
Based on the information supplied, we conclude that the licensee, Maine Yankee Atomic Poner Company (MYAPC), has dem0nstrated ir, its analysis that tne Maine Yankee Atomic Power Station has tne capacity enc capability to manage end mitigate any single incident, such as floodina from e non-Class I system component or pipe, so that this flooding will not prevent a saf e shutcown of the facility.
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FLREn'?.D This report is st.;pliec as part cf ine Se;ectec Electrical i r : t r u r.t r.1-etion ar.a Control Systens Issues (SEIC51; Prc cran Lein; ccnductec f or the U 5.
Nuclear Regulatory Com ission (NRC), Office cf tsuclear Reactcr -iegulaticn,.
D n sion of Oper at ing React or s, to t he L aare ric e L is er:..cre f,ational L : orat ory,
Nuclear Systens Safety Program.
The t<RC work is f unced under the autt.crization entitled " Electrical,
' Instrumentation and Control Sys. tem Support", ELR 201904 031. F i f, n-0121.
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- a n d Pete lii Abstract Fcrew;ra.
iv 1
1.
Introcuction 4.
tvaluation.
2 2.1 General Considerations 2
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Steam,ialve nclosurcs 2
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3 2.2 Turoine Building 2. ~, Primary n,ux111ary cu11dir.g
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5 2.5 Circulating Water Pump Hcuse 3.
Conclusions 6
4.
P.eferences..........................
6 8
Appendix A.
10 Appendix B....
s
1.
INTECDDCTION Sy lctter to the Maine Y cnkee nicn.ic F oner Co car'y (Mt A-L) catec Septenber 27, 1972 [ Pef. 1], the U.S. huclear Fegsiatcry Ccn rission (NCl recaested MYAPC to resiew the Maine Yankee Atomic Pcner 5:ation to ceternir+
nhether the feilure of any non-Class ] (seismic) equipnent coulo resu,1 in a condition su:h as flooding that riight adversely cf fect the safe shutdonn of the facility.
By letter to the hRC cated October 20,1972 [Ref 2], MYAPC responced to the orignal NRC recuest, furnishing information on postulateo failure of the sersice water pumps and the circulating water pumps.
On June 7, 1973, MYAPC submitted acditional detailec infornaticn to the NRC [Ref. 3] which was the result of an extensive study ccnducted on the effects of piping failure external to the Containment builcing.
Proposea modifications to the system as outlined in inis letter were not ecceptable to the NRC.
Revised modificat ion designs were outliroa by Mi APC in their letter to the NRC Cated October 19, 1973 [Ref. 4].
The NRC transmitted to MYAPC on December 17, 1974 [Ref. 5], a so+ cf Guidelines f or Protection f rom Flooding of Ecuipment In.portant to Saf ety.
These guidelines expendec on the scope of MYAPC's original study and requirec f urther study of the flooding problem ty MYAPC.
MYAPC responded to the hRC Guiceiines by letter reports cated Jar.uary 23,1975 [Ref. Ej, and February 19, 1975 [Ref. 7].
The various sources of potential flonding identified by MYAPC and the affected safety-releted equipnent are discussed in Sections 2.2 through 2.5.
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' FC G 1celines tne (c scner.t Ccolir.c nater Syster are Cate; cry I s.,:ters.
[Ref. 5) hac listec these as ncr,-Categ:ry I syste s.
rc-eser, NYJ: ar,cly s : s has treatec these water systems as ncn-Category i systs~s.
All of the ncn-safety relatec systers in Eef er er :e [f] nere inclucec in the licensee's investicaticn.
The licensee nas inclucec an analys's cf ne vulnerability to floccing of eli Class lE e;ulp tr,t recsirec for a safe shutccan 2.1.1 Shutdenn CaDability Saf e shutoonn is accomplishec in the f cllowing mar.r.er:
Poner rate is recutea to cero
- Decay heat is removed by cpening the atncspheric Sent velses
- Steen generator water is maintainec Dy auxiliary feec pumps
- P,eactor coolant system is borated
- When temperature is reaucec to 350 F, arc pressure is recutec to 400 ps ig, flow is establishec inrcugh tre Resitual Heat Eemoval Syst em
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c.c 2.2.1 Safety-Felated Ecuir ent Vulr.erable to Ficccing The saf ety-relatec equipment in this area of ccncern nnicn is requirec for safe shutconn cf the plant, are the stear crisen erergency f eec pu ps anc c'able trays nolding poner caoles.
2.2.2 Sources cf Flooding The source of flooding ir, inis area wculc te a break in the rain feec v.etcr line.
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1.2.3 Lystens enc /cr Frccecures :
4-itigatir9 u.: :: r:I s. - r i:.c.n; ine main are es of cco;ern are tr.e s t e ar cri.u. c > > ie 3 fee: ;. _ s ar.c electric p:nar cables tc tr.e spray ;
- area eina.st ian
7% fa;1 re oce consicerec 1r. this area was a treet in tne eir fisc ' re.
A treat in the main f eec line tc tre stear ger eratcr ncu'.c tri; the icn steam generatcr level and ine steat crisen cue 11iary pu ;: nca c r,ct te availaDie f or f ortner use.
inis fur,ction is iner, harcle:. ty tne e Mctrically criven auxiliary f eed pumps which are lccatec in arJ thcr area that is nct subject to flooding. The energency ciesel gereratcrs are sicec se that they have ample capacity to handle these recuncar1 pumps in the absence cf cf f-site poner.
The power cables in this area have been rerouted f. c-the cable trays to the underground cable vault to minimice potertial ficocirig camage The analysis showec that the rupture cf a rair, f eec lire mill not present a saf e plant shutconn.
2.2.4 Conc lu s ion s he conclude inat the system f eatures in tr.e Stea-Valse Encicsure rrea are adecuate to mitigate ine ef fects of a rupture cf a ron-Eategory : pipe er component on saf ety-related ecuioment recuirec f er a sEf e ;iant snutdenn.
2.3 TUREINE EUILDING 2.3.1 Saf ety-Relatec Ecuiorent Vulr.ernle to Floccing The saf ety-related ecuip ent involved in ine Turrine Euilcing sculc re the emergency ciesel generators, the co ccnent ccoling pumrs, the ur.derground cable trencnes in the diesel generater rooms. the Ccntrol Acom, the 4100 a arc the 480 V switchgear and the Dattery rooms.
2.3.2 Sources of Flooding The sources of floccing which are of concern in the ivrbir e Euilcing, circulating are the main f eed mater lire arc the condensate line, ar:: ine water line..
2.3.3 Systems anc/or Measures to Mitigate the Ef fects of Ficacina A rupture of dny of the high volute nater pipes such as a feec cr condensate line could result in ficcair,g of the grcur c floor of the Turoint Euilding.
The analysis shoned that there are suf ficier.1 openings ir, init.
building to offer ample avenues of egresE for this ficocing. Any ficccing ccnditicn would be detected e crly ar.d corrective acticn taktr. ty the tuilliery operator stationed in this building.
Tnere is also a guaro post just outsice the main door to the Turbine Building and the guard staticnec there can provide early detection and notification to the Control Room of any floccing condition in this building. The analysis did icentify a prcblem area in nhich water could enter and fill the undergrouna cable trench in the diesel generator rooms.
The licensee has constructed curds in f ront of the entrance to e3ch diesel generator room to prevent water from the Turbine builoin,c flocr (Elev. 21') from entering the diesel generator roors.
Breaks in the condensate or feed lines in this area woulC result in an interrupt to the steam generator feed and would result in a plant trip cue to a low water level in the steam generator, a condition which is alarmec in the Control Room.
Saf e shutdown in accomplished as cutlined in 2.2.3 above, by utilizing the electrical auxilialry feea pumps.
The safety-related 4160. cnd 480 V switchgear, and the batteries ar.c battery charging equipment are all loc 2ted at the 45' level whicn is well above any conceivab1 - flooding f rom tne floor lesel in the Turbine Building which is at elevation 21'.
The licensee, however, did not include in his suteittals an enalysis of flooding of safety-related equipment in the Turbine Euilcing (Elev. 21')
resulting f rom a f ailure of a circulating water line or expansion joint.
2'.3.4 Conclusions We conclude that the system features the Turbine Building are adequate to mitigate the effects of flooding due to a rupture of the feec water or condensate piping in this area.
However, the evaluation of flcoding a
of safety-related equipment in the Turbir e Eulicing is inco plete, anc cannet ts ' completed until ne receive the licensee's Er.cly(1s icentifica eccve in section 2.3.3.
2.4 PRIMARY AUXILIARY BUILDING 2.4.1 Saf ety-Related Ecuipment Vulnerable to Floocing The equipment in the Primary Auxiliary Building, (pas), which would Le used f or saf e shutdown and which would be subject to thE effects of flooding are the high pressure safety injection pumps (charging pumps) and the emergency shutdown panel.
2.4.2 Sources of Ficoding The sources of flooding in the PAS are the charging lines from each chaiging pump.
There is also a fluid line f eeding the Heise gauge on the emergency snutdown panel.
2.4.3 Systems and/or Measures to Mitigate the Eff ects of Floccing Each charging pump in the PAS is in a separate ccepartment.
E ach pur:p is subject to the environmental eff ects of a postulated break in that compartment only.
Should a charging pung De taken out cf service f or any reason, its function is replaced by valving,in an installeo spare pump provided for this purpose.
The emergency shutdown panel is ',rcated at elevation ll' in the basement of the PAB which is constructec with floor crains which flow to the building sump.
If a rupture occured in a non-Categcry I system on any floor of the PAB, the water would collect in the sump. An alarm in the sump woulc alert the operators in the Conrtrol Room and corrective action would be initiated. The accumulation of water to any appreciable depth is highly unlikely due to the large floor area of the building and the existence of the alarm system.
The tubing f eeding the Heise gauge on the emergency shutdown panel is de-energized during normal operations by closing the root valve at the sampling line.
Under normal operations there snould be n'a fluid damage io the emergency shutdown panel f rom this source..
2.4.4 Conclusions We concluce that the systems as descrited in the Primary nuxiliary cuilding cre adequate to prevent camege to er.) safety-relatec ecuiprent which r,ight be caused by flooding due to a rupture cf a r.on-C ciegcry ] pipe er component.
2.5 CIRCULATIf,G WATER PUMP HOUSE 2.5.1 Saf ety-Related Ecuipment Vulnerable to Flooding The service water pumps which are recuirec f or a saf e snutdown are located in the Circulating Water Pump House.
2.5.2 Sources of Flooding The source of flooding in the Circulatina Water Pump House woulc be a rupture of a circulating water pipe which coulo cause flooding of the service water pump motors.
2.5.3 Svstems and/or Measures to Mitigate the Ef f ects of Flooding The Circulating Water Syst eri is located at elevaticn 7'0" in this building.
To prevent the floodiaq of the service water pump motors which might result f rom a break in a circulating water system pipe, a reir.f orced concrete weil was constructed f rom elevation 7' to elevction 14' which extencs the f ull length of the Circulating Water Punp House.
The licensee has also installec redundant, multi-lesel alarm switches on the circulating water pump side of the concrete wall which will alert the Control Room operators of a flooding incioent and automatically trip the circulating water pumps when the water level reaches a cepth of ten inches.
2.5.4 Conclusions We conclude that the measures t aken by the licensee are adequate to protect the service water pump motors which are requireo f or a saf e shutdown of the plant.
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3.
CONCLUSIONS Based on information supplied by the licenste, ne concluce that MYAPC has demonstrated in their analysis that the Paine Yariee Atonic Loner Station, excludir g the Turbine building, has the Capacity anc capacility to manage &nc mitigate any single incident, such as flooding from a ncn-Class 1 System component or pipe, sc that flooding will not pre',ent the saf e shutcown of the plant.
The licensee has further shown in the analysis for those areas aadressed, that no single f ailure would result in common moae f ailure of redundant saf ety-related equipment.
We recomicond that the NRC require the licensee to submit its analysis of flooding of scfety-related equipment in the Turbine building resulting from f ailure of the c irculating water piping or expansion joir,t in this area.
The receipt of this analysis is required to enable us to complete the evaluation for flooding of safelty-related equipment / systems at the Maine Yankee Atomic Power l'ation.
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4 R E F E R E f,C E S 1.
U.S. Nuclear Regulatcry Ccrcission (t,RC) letter to Maine Y a%ee Atcric Power Company (MYAPC), datea September 27, 1972.
2.
MYAPC letter to hRC dated October 20, 1972.
3.
MKYAPC letter to NRC dated June 7, 1973.
4.
MYAPC letter to NRC dated October 19, 1973.
5.
NRC letter to Yankee Atomic Electric Conpany datea Decemcer 17, 1974.
6.
MYAPC letter to NRC dated January 23, 1975.
7.
MYAPC letter to NRC dated February 19, 1975.
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APPENDIX.
UNITED STATES ATOMIC EN S GY COM*I55 ION Weshington, D.C.
2C545 Docket No. 50-309 September 27, 1972 Maine Yankee Atomic Power Company ATTN:
Mr. William H. Uunham Presiaent 9 Green Street August, Maine 04330 Gentlemen:
A f ailure of an expansion bellows in the circulating water line which serves the main condenser recently occurred at Quad-Cities Unit 1.
The resultant flooding caused degradation of some safety related equipment.
You are requested to review Maine Yankee Atomic Power Station to cetermine whether the f ailure of any non-Category 1 (seismic) equipment, particularly in the circulating water system ano fire protection system, could result in a condition, such as flooding or the release of chemicals, that might potentially adversely affect the perf ormance of s af ety-related equipment required f or saf e shut 00wn of the f acility, or to limit the consequences of an accident.
The integrity of barriers to protect critical equipment f rom pctentially damaging conditions should be assumed only when the barrier has been specifically cesigned f or such conoitions.
If your review cetermines that safety-related equipment could be adversely 7.f fectec, providc your plans and schedules for corrective action.
Please submit your response within 30 days of receipt of this letter.
Sincerely, R. C. DeYoung Assistant Director for Pressurized Water Reactors Directorate of Licensing 9
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r. c a <. r e n c e E. M i r.r. i c k V i ce P re s i dent, E n'y r'eer i r c 20 Turr. pike. Rcac
' estt;cro, Massacr.usetts OlEEl Jonn A. Ritsher, Esquire scres and Grey 225 Franklin Street Ecston, Massacnusetts 02110 DISTRIBUTION:
Docket AEC PDR R. Reading PWR-3 Peading RKlecker DCrutchfield RCDeYoung RBoyd OGC VWilson (2) e P E8 e
APPENDIX E hRC GUIDELlhES FOR PROTECTION FROM FLOODlh5 0F EQUIFMEhi IFDRTAhl TO SAFETY Litensees are required to investigate their facilites to review their designs to assure that ecuipment important to safety wiIl not be damageo by
- flooding due to rupture of a non-Class I system component or pipe such that engineered saf ety f eatures will not perform their aesign function.
No single incident of a non-Class I syst?m component or pipe f ailure shall prevent saf e shutcown of the facility.
Review of responses to the letters should assure that the plants meet the following guidelines:
1.
Separation f or redunaancy - single f ailures of non-Class 1 system components or pipes shall not result in loss of a system important to safety. Redundant saf ety equipment shall be separated and protected to assure operability in the event a non-Class 1 system or comp Tent fails.
2.
Access doors and alarms - watertight-barriers f or protect ion ' rom flooding of equipment important to safety shall have all ;ccess coors or hatches fitted with reliable switches and circuits that provide an alarm in the control room when the access is open.
3.
Sealed water passages - passages or piping and other penetrations through walls of a room containing equipment important to safety shall be sealed against water leakage f rom any postulated f ailure of non-Class I water system.
The seals shall be designed f or the SSE, including seismically induced wave action of water inside the affectea compartment auring the SSE.
4.
Class I watertight structures - walis, doors, panels, or other compartment closures designed to protect equipment important to safety from dariage due to flooding fror, a non-Class I system rupture shall be desior,ed for the SSE, including seismically induced wave action of sater insiae the af f ected compartment during the SSE..
5.
nater level alarms anc trips - rccr.s cont ain1r4 re-us syste-components anc pipes nhose rupture cculc result u,
1.cc cen e;e te equipment important to saf ety shall base level clarrs cr,c pump trips (where necessary) that alerm in the ccrtrol rcc~ arc licit flo:.cir.g te within the cesign flood vclume.
Redurcar.ce cf swittnes is re ;uirec.
Critical pump (i.e. hign volume flon, sach as cor. denser circulatinc water purps) trip circuits shoula meet IEEE 27i criteria.
6.
Class ] equipment should be located or prctected such that rupture of a ncn-Class I system connectec to a toner containing nater or bocy of water (river, lake, etc.) will not result in f ailure of the ecuipnent f rom flooding.
7.
The saf ety analysis shall consider simultaneous loss cf of f site poner with the rupture of a non-Class I system component cr pipe.
The licensees' responses should incluce a listing of the non-Class I syttems consicered in their analysis.
These shoula inciuce et least tne following systems:
Firewater Demineralizec Later Service Water Drains Condensata Heating Sciler Cenoensate Feecnater Concenser Circulating nater Reactor Building Cooling Water
, Makeup Turbine Building Cooling Water Potable Water If the licensee indentifies deficiencies, he should cescribe interim and final corrective action to be taken anc provide a schecule f or completion of any required modifications.
All corr ctive action shoulc be ccaple':'d as espeditiously as is practicable.
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