ML19224A797
| ML19224A797 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/16/1979 |
| From: | Macmillan J BABCOCK & WILCOX CO. |
| To: | |
| Shared Package | |
| ML19224A796 | List: |
| References | |
| NUDOCS 7905300391 | |
| Download: ML19224A797 (30) | |
Text
-
6ne/a.5are /
U?i!TED STATES NUCLEAR REGULATORY CC"li!SSION ADVISORY CC:Oi!TTEE CN REACTOR SAFEGUARDS April 16, 1979 Washington, D.C.
Statement on Sehalf of THE BA3CCCK & WILCCX CC:GA'IY 168 090 7905ggg3 @e nv
OUTLINE I.
INTRODUCTION A.
PLANT OVERVIEW B.
SUMMARY
OF B&W ACTIONS IN SUPPORT OF TMI-2 C.
DISCUSSION OF SIGNIFICA'IT FACTORS IN THE INCIDEIT II.
ACTIINS IMPLEMENTED FOR OPERATING PIACTORS -
A.
ACTIONS ALREADY TAKri B.
NEtt'4-TERM ACTIONS C.
LONGER-TERM. ACTIONS III.
CONCLUSIONS m
6 168 091
PPISENTATION BY J.
H.
MacMILLAN TO ACRS GCOD AFTER2!CCN.
MY NAME IS JOHN MacMILLAN.
I AM VICE-PRESIDENT CF THE NUCLEAR POWER GENERATICN DIVISION OF THE BAECCCK & WILCOX COMPANY.
THE DIVISION IS RESPONSIBLE FOR THE MARKETING, ENGI'iEERING, PROJECT MANAGEMENT, AND RELATED SERVICES OF THE NUCLEAR STEAM SYSTEMS SUPPLIED TO THE UTILITY, INDUSTRY BY BABCCCK & WILCOX.
I.
INTRODUCTION TODAY I WILL DISCUSS THE INCIDENT AT THREE MILE ISLAND-2, WITH SPECIAL FliPHASIS CN B&W'S ACTIVITIES WHICH WE HAVE CURRENTLY UNDERWAY OR SHORTLY WILL HAVE UNDERWAY AS A RESULT OF '" HAT INCIDENT.
I HAVE WITH ME TODAY A NUMBER OF SUPPORT PERSONNEL, MANY OF WHOM ARE FAMILIAR TO THE COMMITTEE, TO ASSIST IN ANSWERING QUESTICNS.
FROM THE TIME THAT B&W WAS FIRST NOTIFIED OF THE TMI-2 INCIDENT, B&W'S NUMBER ONE PRIORITY HAS SEEN TO PROVIDE SUPPORT AND ASSISTANCE TO 3 RING THE PLANT TC A COLD SHUTDCWN CCNDITICN.
CLOSELY PARALLELING THAT HAVE BEEN EFFORTS TO ASSURE CCNTINUED SAFE OPERATION OF THE OTHER B&W OPERATING PLANTS.
AS THE SITUATION AT THREE MILE ISLAND CCNTINUES TO IMPROVE, WE WILL 3E STRENGTHENING CUR EFFORTS RF. LATED TO THE CTHER PLANTS.
CN THE BASIS OF WHAT IS NCW ICIOWN ABOUT THE FACTORS AFFECTING i68 092
.- :su a
TH
,u 3
u,.. --: v :
- m. u n,. a.u.n.u. P.. m.:
,-, S..., S....
n :.a,.
.=n a.
x u r.:.
.a v :
.s
- m. A.s.1 3*./
mu..r fJm. '..' m. *. r.S, 3 &*a*,
n.s t. D
- m..u..r. si*.JC mO.nIS*u*;r
- m..u..r. C e, s.*m..? s. t L' r D m
SAFE OPERATICN OF THOSE PLMITS.
MY RD! ARKS TODAY WILL BE PREFACED BY:
1)
AN OVERVIEW OF THE B&W NUCLEAR STEAM SYSTDI, WITH EMPHASIS CN THOSE PLMIT FEATURES OF RELEVANCE TO THE
- INCIDENT, 2)
A SU:! MARY OF THE SPECIFIC ACTICNS TAKEN SY B&W TO SUPPORT MID ASSIST THE LICENSEE I:I CCN:IEC" ION WITH THE TMI-2 INCIDENT, A'ID 3)
OUR PRELIMINARY VIEWS CN TFb SIX FACTORS IDE5hTIFIED BY THE NRC IN ITS I.E. BULLETIN 79.05A AS SIG:iIFICMITLY AFFECTI'IG THE COURSE OF 'I T. INCIDENT.
~
IN THAT CCNTEX", I WILL THEN PROCEED TO ADDRESS:
1)
THE I 0!EDIA"'E ACTIONS TAKEN SY 3&W, THE U"'ILITIES,
MID THE NRC TO ASSURE CC'T"I'iUED SAFE OPERATICN OF OTHER B&W REACTORS M!D 2)
CUR PLANNED NEAR-MID LCNG-TERM ACTICNS TO PROVIDE FURTHER ASSURANCE OF CCNTI'IUED SAFE OPERATION.
168 093
. A.
PLAN"; OVERVIEW FOR THE PURPOSE OF TODAY'S DISCUSSICN, I WILL PROV!DE A BRIEF OVERVIEW CF TYPICAL B&W DESIGN FEATURES.
Slide 1 THE BA3CCCK-177 FUEL ASSEMBLY NUCLEAR STEAM SYSTD1 USES Pri:mry System TWO STEAM GENERATORS, FOUR REACTOR CCOLANT PUMPS, A PPISSURIIER AND ASSCCIATED PRIMARY PIPING.
"'WO ASME CODE SAFETY VALVES ARE MCUNTED ON TOP OF THE PRESSURIIER.
ALSO MOUNTED ON THE PRESSURIIER IS AN ELECTRCMATIC PILOT-OPERATED RELIEF VALVE WITH RDIOTELY OPERATED ISOLATION VALVE IN SERIES.
THE SAFETY M;D FILIEF VALVES DISCHARGE TO A CUENCH TANK WHICH HAS A STCPID WATER SUPPLY TO CCNDENSE THE STEAM DISCHARGE.
~
Sl* 2 THE PPESSURIIER IS CONNECTED TO THE P2 ACTOR CCOLANT SYSTEM Elevaticn AT THIS POINT.
(Indicate on slide.)
Slide 3 IN THE SECCNDARY OR STEAM SYSTEM OF TMI-2, CCNDENSATE FRCM Seccrf.ary Systst THE CONDENSER IS DIRECTED THROUGH THE CCNDENSATE POLISHERS AND CONDENSATE 3 COSTER PUMPS TO THE SUCTION OF THE MAIN FEEDWATER PRIPS AS SECWN CN THE SECONDARY SYSTD1 DIAGRAM.
FROM THE MAIN FIEDWATER PUMPS, THE FEEDWATER PASSES THRCUGH THE FEEDiiATER CONTROL VALVES TO EACH OF THE ONCE-THROUGH STEAM GENERATORS WHERE IT IS CONVERTED TO SUPERHEATFP IT AM WHICH FLOWS TO THE TURBINE.
IN THE EVENT OF THE LOSS OF MAIN FEECWATER TO THE ONCE-THROUGH STEAM GENERATCRS, AUXILIARY FEEDWA'"ER IS PIQUIRED i
AND THEP2 FORE THE AUXILIARY FEEDWATER SYSTEM IS AUTOMATICALLY ACTUATED.
AUXILIARY FEEDWATER FROM EITHER THE CCNDENSER OR 168 094
- CONDENEATE STORAGE TANKS IS PROVIDED THROUGH THREE AUXILIARY FEEDWATER PUMPS - CNE-FULL CAPACITY TUR3INE DRIVEN AND TWO-HALF CAPACITY MOTOR DRI'/EN - FOR INJECTION AT THE TOP OF EACH ONCE-THRCUGH STEAM GOIERATOR.
AS DESIGNED, THIS ARPJdiCDiC C WILL SATISFACTORILY 1.CCOm10DATE A LOSS-OF-FEEDWATER (LOFW) TRANSIENT.
THIS IS CONFIRMED BY OUR SAFZ"Y A'IALYSES AND EXPERIENCES WITH '
A NUMBER OF LOFW TRANSII'CS WHICH HAVE CC"URRED AT THIS AND OTHER S&W PLANTS.
B.
SUMMARY
OF B&W ACT!ONS i SUPPORT OF TMI '2 EARLY ON THE MORNING OF MARCH 28, B&W MANAGDLENT IN LYNCH 3URG WAS NCTIFIED OF THE INCIDENT.
IMMEDIATELY THEREAFTER, WE CONVENED A MEETING OF EXPERTS TO IDENTIFY SPECIFIC INFORMATION A'iD MANPOWER NEEDS FOR PROVIDING SUPPORT TO THE LICENSEE.
AS A RESULT OF THAT MEETING, FIVE PEOPLE WERE DISPATCHED TO THE SITE AND BY EARLY AFTERNCON _A CCMMUNICATION CEICER WAS ESTABLISHED IN LY'ICH3URG WHICH WAS STAFFED BY OUR SENIOR MANAGEME'IT AND TECHNICAL PEOPLE.
BY THE SECCND DAY WE FAD ESTABLISHED AN ORGA'CIATION TO PROVIDE ROUND-THE-CLCCK SUPPORT.
WITHIN THAT ORGANIIATICN, SPECIFIC RESPCNSIBILITY WAS ASSIGNED FOR EVALUATI'!G DATA OBTAINED FROM THE SITE AND DEVrLOPING A POSTULATED SEQUENCE OF EVENTS, FOR CONDUCTING SD!ULATIONS OF THE EVE:TS ON THE 3&W CONTROL RCCM 6IMULATOR AND FOR CEVELOPING AND RECCM'4ENDING CCNTINGENCY PRCCEDURES FCR PERFORMING COMPARISCNS OF PHYSICAL PLANT DATA FOR CONDUCTING SPECIFIC ANALYSES AS RECUESTED BY THE LICENSEE OR THE NRC, AND FOR REVIEWING REPORTS OF OTHER LOSS-OF-FEEDWATER TPJdISIENTS.
168 094. 5 b
AS THE COURSE OF THE INCIDCiT PRCGRESSED AND THE NEED FOR SUPPORT INCREASED, WE DISPATCHED ADDITICNAL PEOPLE AND EQUIPMENT TO THE SITE.
I PERSCNALLY WENT TO THE SITE TO HEAD THE B&W ON-SITE TEAM.
AT THE PEAK OF THE S&W EFFORT CN THE INCIDCIT, WE HAD DEPLOYED 47 PEOPLE TO THE SITE AND SCME 213 PEOPLE IN LYNCHBURG WERE ASSIGNED TO THE CONTROL CENTER AND RELATED SUPPORT ACTIVITIES.
CUT OF THIS INITIAL EFFORT GREW AN ORGANI::ATIONAL FRAMEWORK WHICH GAVE US THE CAPABILITY TO SHIFT CUR EMPHASIS
~
TO EFFORTS TO ASSURE CONTINUED SAFE OPERATICN OF THE OTHER B&W OPERATING REACTORS.
C.
DISCUSSICN OF SIGNIFICANT FACTORS IN THE INCIDENT Slide 4 FOR THE PURPOSE OF TODAY'S DISCUSSION, WE ACCEPT THE SEQUENCE Six Factors AND LIST OF SIX SIGNIFICANT FACTORS IDCiTIFIED BY THE NRC IN ITS IE BULLETIN 79.05A.
THUS, I WILL NOT RETREAD GRCUND ALP"ADY COVERED BUT INSTEAD WILL SUMMARIZE OUR VIEWS ON THE SIGNIFICANCE OF THOSE FACTORS AND THEIR SECUCICE.
o FIRST, AFTER THE LOSS OF FEEDWATER TRANSIENT WAS UNDERNAY, THE ABSENCE OF AUXILIARY FEEDWATER TO PROVIDE SECONDARY SIDE CCOLING FOR A PERIOD IN EXCESS OF 8 MINUTES RESULTED IN DELAY IN RESIDUAL HEAT REMOVAL AND TEMPERATURE INCREASE IN THE REACTOR COOLANT SYSTEM.
THE PRESENCE OF AUXILIARY FEEDWATER, AS DESIGNED, WOULD HAVE STABILI::ED REACTOR
~
COOLANT TEMPERATURE EARLIER IN THE TRANSIENT AND ELIMINATED A CCMPLICATING DISTRACTICN TO THE OPERATOR.
168 096 9
w o-
,, 6 --
AS A RESULT OF THE SYSTEM PRESSURE INCREASE,
- SECOND, THE PILOT-OPERATED PRESSURIIER RELIEF VALVE OPENED AS DESIGNED, BUT DID NOT RESEAT PROPEPJ Y, THUS ALLCNING REACTOR CCOLANT SYSTEM PRESSURE TO CCNTINUE DECPIASING.
THE SIGNIFICANCE OF THIS FACTCR IS NOT CNLY IN OUR VIEW, MORE IMPORTANTLY, THE FAILUPI OF THE VALVE TO RESEAT SUT,
/
THE TIME WHICH ELAPSED SECiEEN THE FAILURE TO PISEAT AND THE RSCCGNITION THAT THIS HAD OCCURRED.
WHICH HAD SEEN THE HIGH PPISSURE INJECTION SYSTEM, TH IRD,.
AUTOMATICALLY ACTUATED AS DESIGNED CN LOW P2 ACTOR C SYSTEM PRESSURE, WAS PPIMATURELY TERMINATED EVEN THCUGH THERI WERE INDICATIONS OF AN OPENING 'N THE REACTOR CCOLAN SUCH AS INCREASING CUENCH TANK PPISSUPI AND PRESSURE SOUNDARY, DECBFASING REACTOR CCOLANT SYSTEM PRESSUPE.
FOURTH, THE CONTAINMENT DID NOT ISOLATE AT THE TIME THE THIS IS IM EMERGENCY COP 2 CCOLING SYSTEM WAS ACTUATED.
THIS LED TO RADICA.
ACCORDANCE WITH THE LICENSED DESIGN.
WATER IN THE REACTOR BUILDING SUMP AND THE LACK OF CC ISOLATICN ELOWED THIS FLUID TO BE PUMPED TO THE AUTILI 6
SUILDING, FRCM WHICH SUBSEQUENT RADIATICN FILEASES CCCURRED.
FIFTH, EIGH PRESSUP2 INJECTION WAS EVIDENTLY MANUALLY WE OPERATED SASED CN HIGH PRESSURIIER LEVIL INDICATICN.
HAVE CCNDUCTED REVIEUS OF CATA FRCM THPIE MILE ISLA PERFORMED ANALYSES THAT LEAD US TO CCNCLUDE THAT THE INDICATED PRESSURIIER LEVEL WAS NOT SIGNIFICANTLY IN WE BELIEVE THAT THE PRESSURIIER ERROR (; ONE FOOT).
168 097 9
WAS ESSE::TIALLY FULL CURING A LCNG PERIOD CF THIS TRANSIE T, SUT A PORTION CF THE PIACTOR CCCLA';T SYSTEM WAS VOID.
CCNSECUENTLY, TEP24INATICN OF HIGH PRESSURE INJECTION FLCW SECULD NOT HAVE SEEN BASED CN THE SI::GLE PARAMETER CF PRESSURIIER LEVEL.
SIXTH, ALL FOUR REACTOR CCOLANT PU11PS WERE SECURED.
ALTHCUGH SECURING ONE PIACTOR CCOLANT PUMP IN EACH LCCP IN RESPCNSE TO INDICATICI, OF LCW CCOLA';T FLCW MAY BE ADVISABLE, SECURIMG ALL PUMPS UNDER THE CIRCUMSTANCES T H7
- SENT CAUSED AN UNCCVERING OF THE CORE.
0 4
8 h
er 168 098 3
. _ _ II.
ACTICNS IMPLEMENTED FOR CPEPATING REACTORS OUR ANALYSIS OF THE FOREGOING FACTORS HAS LED US TO CONCLUDE THAT, THE S&W SYS"' EMS CAN BE OPERATED SAFELY FCR A 3PECTRUM CF ECUIPMENT FAILURES, INCLUDING THOSE EXPERIENCED AT TMI-2.
- ECER, THE SEVERITY OF THE TMI-2 INCIDENT WARRA2iTS TDELY ACTICMS TO ENCOURAGE PROPER OPERATOR PERFORMANCE IN THESE EVENTS.
CUR
~
RECOMMENDED ACTIONS CAN AND SHOULD SE IMPLEMENTED IN CHRONOLOGICAL STEPS TO ASSURE AND ENHANC CONTINUED SAFE OPERATION.
THUS, M'Y DISCUSSICN CONSISTS OF ADDRESSING:
a)
THE ACTIONS ALREADY TAREN, b)
THE NEAR-TEP24 ACTICNS TO BE TAKEN,,AND c)' LCNGER-TEPli ACTIONS APPROPRIATE TO MEET THCSE OBJECTIVES.
BEFORE PROCEEDING TO A DISCUSSICN.OF THE SPECIFIC _ ACTIONS, I WOULD LIKE TO ESTABLISH A CCNTEXT FOR THOSE DISCUSSIONS WITH OCR INITIAL VIEW CF THE LESSON LEARNED FRCM THE INCIDENT.
CUR ANALYSIS OF THE SIX FACTORS IDENTIFIED BY THE NRC H M YIELDED A m iPo 5 Prirr.iples SET CF THREE BASIC PRINCIPLES WHICH h*E BELIEVE WARRAN"' EMPHASIS IN CONSIDERING ANY FUTURE ACTION.
FIRST, FINEWED EMPHASIS MUST BE PLACED IN THE NEAR TEPM CN ADMINISTRAT'VE CC r"ROLS TO ASSURE THAT PLANT SYSTEMS D!PORTANT TO SAFETY ARE AVAILA3LE.
IN THE LONGER TERM, CCNSIDERATICN SHOULD BE GIVIN TO WHETHER PLANT SYSTEl4S TO AUGMENT THOSE ADMINISTRATIVE CCNTRCLS SECULD 3E DEVELOPED AND IMPLE-MENTED.
SECCND, RENEWED Es1PHASIS MUST BE PLACED CN MAINTAINING THE INDIVIDUAL OPERATOR'S FCCUS UFCN THE FUNDAMENTAL PHYSICAL PRCCESSES WHICH ASSUP2 CORE COCLING, AND ON DETEPJ4INING THAT CUR SYSTEMS COMPLE ENT CR INCREASE THE LIRELIHCCD OF MAINTIANING THAT FCCUS IN ANY EVENT IN THE NEAR TEPM, THIS MEANS PLACING EMPHASIS IN 168 099 M*6
_g_
OPERATOR TRAEiniG PROGRAMS AND INSTRUCTIC.NS ON THE FACT "FJT THE MOST STA3LE AND FORGIVING CCNDITICN IN A PRESSURI':ED WATER FIACTOR
~
IS ONE IN WHICH THE FIACTOR CCOLANT IS SUECCOLED, AND COPI CCOLING IS MAINTAEiED.
AS A CORACLLARY, A SATURATED LCOP MUST SIGNAL IN THE MIND OF THE OPERATOR:
1)
EXTREME CAUTICN BEF0PI SECURING ANY MEANS OF MAINTAINING PRE!ARY SYSTEM INVENTORY, 2)
A WARNING
~
THAT A SYSTEM OPENING EXISTS, AND 3)
A PROHIBITICN AGAINST ANY ACTION WHICH MIGHT DIMUi!SH CORE CCOLING.
THIRD, ANY ACTIONS OR MODIDIFICATICMS IMPLEMENTED MUST 3E CCNSIDERED IN THE BROADER CONTEXT CF TCTAL P! ANT SAFETY.
HASTY AND ILL-CONSIDERED ACTIONS, WHICH MIGHT BE PARTIALLY RESPCNSIVE TO THE TMI-2 E'IENTS, COULD, 2i CERTAIN CASES, PRCDUCE ADVERSE IMPACTS DI OTHER SAFETY SYSTD15 WHICH WERE NOT INVCLVED AT TMI-2.
WITH THAT INTRODUCTION, I WILL PRCCEED TO DISCUSS THE ACTIONS ALREADY TAEN, AND THOSE ANTICIPATED FOR THE NEAR AND LONGER TERM.
A.
ACTICNS ALPIADY TAE'I B&W CCNTACTED REPRESENTATIVIS OF ITS OTHER OPERATING PLANTS BY TELEPECNE BETWEEN MARCH 29 AND MARCH 31 TO PROVIDE THEM WITH INFORMATION FIGARDING TMI-2 AND TO PICOMMEND THAT THEY HAVE STATION PERSONNEL CHECK THE CONFIGUPATICN CF THEIR AUXILIARY FEEDWATER SYSTEMS AND MAKE SUCH INSPEC"IGNS AND TESTS AS NECESSARV TO CONFImi THAT THE SYSTE"S NOULD INITIATE FLCW OF AUXILIARY FEEDWATER UFCN ACTUATICN.
168 100 a
. BY APRIL 1, 3&W HAD FURTHER DATA PIGARDING TMI-2 WHICH WE BELIEV-
......~
ED WCULD BE HELPFUL TO OTHER 3&W' OPERATING PLA'iTS IN UNDERSTA:iDI:IG THE C1.USES AND CCURSE OF EVENTS CF THAT INCIDENT.
I CONTACTED EACH OF THE JTILITIES A:iD INVITED THEM TO SEiD REPRESE:iTATIVES TO A
.sLnm.. G -sJ m.f A~mL,Ra.
7 a
SOON THEREAFTER NRC ISSUED BULLETIN 79-05.
THE MEETING WAS HELD ON APRIL 3 AND.: IN LY'ICH3CRG WITH EACH OF THE UTILITIES HAVING REPRESENTATIVES PRESENT.
AT THAT MEETING, B&W PPISENTED THE DATA WE HAD ON THE INCIDE:IT A'iD DISCUSSED WITH THE REPRESE:ITATIVES SIMILARITIES AND DIFFERENCES IN THEIR EQUIPMENT AND PRCCEDURES FRCM THOSE OF TMI-2.
ADDITIONAL INFCEMATION WAS PROVIDED AD SPECIFIC QUESTICNS SY CUSTOMER REPRESENTATIVES WERE A'iSWEPID.
SULLETIN 79-05 WAS. DISCUSSED AND B&W PROVIDED ASSISTANCE IN RESPONDING TO BULLETI'T 79-05 BCTH DURING THIS MEETING AliD SUBSECUDIT THERETO.
THE FIRST B&W ADVISORY WAS FORWARDED BY TELECDPY ON APRIL 2.
IT PICCMMENDED, AS A PPICAUTIONARY STEP, THAT THE OPERATORS PERFORM A THOROUGH REVIEW OF THE AUXILIARY FEEDWATER SYSTEM, ASSCCIATED SUPPORT AND CCNTROL SYSTDiS, A'ID NORMAL MAINTENANCE AND EMERGENCY PRCCEDUPJS TO IDENTIFY POTENTIAL PROBLEMS THAT MIGHT LEAD TO FAILURE OF THE AUXILIARY FEEDWATER SYSTEM WHEN IT IS REQUIRED.
IT ALSO RECCMME'iDED THAT THE DESIGN OF THE AUXILIARY FEEDWATER SYSTDi AND THE CPERATING, MA_"JTENANCE, AND EMERGECY PRCCEDURES ASSCCIATED WITH THIS SYSTEM BE PSVIEWED WITH ALL OPERATORS, MAINTENAliCE A'ID SUPERVISORY PERSONNEL WITH SPECIAL EMPFTSIS ON ITS IMPORTANCE TO PLANT SAFETY.
168 1.01 4
V
THE SECOND ADVISCRY WAS FORWARDED SY TELECOPY TO OPERATING m.e - c. u.r,. D.D. u.n-.
.v.r
- u. r.
.Seen.
I.
m C L,S. v Lr u S Ch n.e R.--
P r.n i.
..w.
.t
.e u
HIGH PRESSURE !'iJECTICN SYSTEM HAS BEEN ACTUATED 3ECAUSE OF A LCW PPISSURE CONDITION, IT SECULD RD!AI'i IN OPERATION U'ITIL b P r.C Ie m. C P a-,,. Cn,D-.yn.c eX S..
T u..r. CCs.4 D.7..rC.,iS.e.a-. rD ne r
....a o..
THAT. OPERATION OF THE HIGH PRESSURE I:iJECTICN CONT!' ICE FOR AT LEAST 20 MINU"'ES AND AS LONG THEREAFTER AS NECESSARY TO OBTAIN TDiPERATURES IN THE LCOP WHICH ARE AT LEAST 50*F BELOW SATURATION m iPEeATUPS; OR THAT OPERATICN CF THE HIGH PRESSURE INJECTICN CC:ITI:iUE C'ITIL SOTH LCW PRESSUPI INJECTICN PCMPS ARE FLCWING AT A RATE OF AT LEAST 1000 GALLONS PER MINUTE EACH IN A STABLE CONDITICN AND HAVE BEE:i 50 FLCWING FOR AT LEAST 20 MINUTES.
THE ADVISCRY ALSO CALLED FOR CONTINUED OPER5 TION OF AT LEAST CNE REACTOR CCOLANT PUMP PER LCOP IF THE HIGH PRESSURE INJECTION SYSTD1 HAS 3EEN ACTIVATED AND THE REACTOR CCOLANT PUMPS ARE IN OPERATION AT THE TIME OF ACTUATION.
ON APRIL 6, ANCTHER MEETING 3E* WEEN 3&W AND THE CWNERS WAS HELD SPECIFICALLY TO DISCUSS I'IFOP3.ATICN AVAILABLE A.'ID B&W RECOMMENDATIONS PZGARDING THE RESPONS?S THE UTILITIES 'iERE PREPARING TO II SULII*IN 79-05 AND 05A.
WE PROVIDED FURTHER ASSISTA' ICE IN REGARD TO ITD1 1 INVOLVING UNDERSTANDING THE SEQUENCE OF EVENTS, AND I*EM 3 I'PICLVING OPEPATI:iG PRCCEDURES FOR COPING WI~H TRA:iSIENTS WITH A POTENTIAL FOR I'ITRCDUCING VOIDS IN THE REACTOR CCCLA.'!" SYSTEM.
168 102 O
..-nr L,,.ID e R.e..a,.D. u..n,...n.,
AC.,.,,,. S
., o r -., c.,.. r D A., D n, L,D.-. S 4
CCNDUCTED IN RESPONSE TO NRC SULLETIN 79-05 AND 05A HA'/E BEEN POS-.rt/;.
- m. h. -, C O L.P L,D
<a-.. u.
. e..e,I.C. c S. n, e.:.
e r,7.e... O.r L..I,.-. y A.
s.
..s
.a
.r o
RESPONSES TO THOSE BULLETINS, AND ITS ONGOING R.rVIEW CF THE r u.. C v D. e,.1.,
...O V.D. e.
p:
. rG.
- d. d CC..Lr -, r.,..C,
-u.a,.
- m. u..r. -. G,..,. r C.. m.
eAC. O.a.S er s.
A.
...... i.
IN THE TMI-2 INCIDENT HAVE BEEN PROPERLY ADDRESSED.
THUS, NE BELIEVE THAT THE ACTIONS TAKEN TO DATE BY B&W, THE UTILITIES, AND THE NRC PROVIDE ADECUATE ASSURANCE CF CONTINUED SAFE OPERATICN WHILE CCNSIDERING ADDITICNAL NEAR AND LON';ER TERM
' ACTIONS.
B.
NEAR-TERM ACTIONS ALTHOUGH WE BELIEVE THAT THE STEPS TAKEN BY THE UTILITIES, THE NRC, AND B&W ASSURE SAFE OPEPA* ION OF NUCLEAR' UNITS, WE RECOGNIIE THAT ADDITICNAL MEASURES MUST BE TAKEN SO THAT OPERATORS ARE BETTER ABLE TO MANAGE TRANSIENTS.
I WCULD LIRE TO SUMMARIII THE ACTICNS B&W HAS CURRENTLY C'IDERWAY OR WILL BE COMMENCING SCCN TC FUR *HER.97 HANCE THE SAFETY OF B&W UNITS.
1.
B&W IS PREPARING A SUPPLEMENTARY ADVISORY REQUESTING THAT ALL OPERATING AND SUPERVISORY P.
.CNNEL REVIEW THE INDICATICNS OF AN OPENING IN THE REACTOR COOLA.'IT SYSTEM BOUNDARY, RESULTING FRCM AN OPEN RELIEF VALVE.
THESE SUPPLEME'ITARY INSTRUCTIONS WILL BE ISSUED THIS WEEK TO ALL CF CUR CUSTCMERS WITH OPERATING. REACTORS.
168 103 2.
DURING THE APRIL 6TH MEETI';G h!TH P2PRESE::TATIVES OF CUR OTHER B&W CPERATING PLAli"'S, S&W SUGGESTED A SPECIAL TRAINI:IG PROGRAM FOR OPERATORS TO BE CCNDUCTED CN CUR SIMULATOR SO THAT THEY WOULQ BECCME MORE FAMILIAR WITH THE T!!I-2 SECUENCE OF EVE;TS.
ON MONDAY, APRIL 9, B&W BEGAN CC:iDUCTING TRAIN ::G FOR OPERATING A:iD MA'!AGEMENT PERSONNEL ON THE EVE::TS INVOLVED IN THE S1 % 6 TMI-2 INCIDENT.
THE TRAINING CCNSISTS OF THE FOLLOWING:
T:2Lning DISCUSSION OF THE TMI-2 TRANSIENT FROM THE INFORMATICN AVAILA3LE TO B&W.
DEMCNSTRATION OF THE INCIDEN"' ON THE B&W SIMULATOR.
TRAINING SESSION ON THE SI_'iULATOR tiAVING STUDENTS RECOVER THE PLANT FRCM A DEPRESSURI2ATION EVE'IT WHICH INVOLVT.S THE FOP 24ATICN OF STEAM VOIDS IN THE REACTOR CCOLANT SYSTEM CUTSIDE THE PRESSURI':ER.
SIX OPERATCRS ARE INCLUDED IN EACH TRAINING SESSION.
THE TRAINING SESSIONS LAST CNE DAY.
AT THIS TIME, 33 CPERATORS HAVE BEEN THRCCGH THE CCURSE AND 99 MORE HAVE DEFINITE SCHEDULES ESTA3-LISHED INCLUDING CPERATORS FROM ALL OPERATING B&W PLANTS.
WE BELIr/E THIS COURSE WILL SIG:::FICANTLY CCNTRIBUTE TO THE ABILITY OF OPERATCRS TO RESPCND PROPERLY TO TRANSII:;TS IN GENERAL A:.
THE LOSS-OF-FEEDWATER TRA'ISTENT IN PARTICULAR.
WE ALSO SELITIE THAT IT WILL SERVE TO EMPHASIZE THE PRCCEDURES TO 3E FOLLCWED IN IDENTIFYING A SMALL REACTOR CCOLANT SYSTEM LEAK, AND PARTICULARLY AN OPEN PRESSURI':ER RELIEF VAL 7E.
168 104
...- 3.
BASED CN INFORMATICN CURRE:ITLY AVAILABLE TO B&W, THE EQUIPMENT IN BOTH THE PRIMARY A'ID SECONDARY PLA';T, WITH THE EXCEPTICN OF THE PILCT-OPERATED PRESSURI':ER RELIEF VALVE, PERFCR'1ED AS DESIGNED.
HCWEVER, CONSIDERI::G THE UNANTICIPATED EVENTS AT TMI-2, DESIGN IMPRCVC.r.JTS SECULD BE CCNSIDERED IN ORDER TO ASSIST PLANT CPERATORS IN CCNTROLLING NUCLEAR POWER PLANTS DURING TP.'JISIENTS.
SOME POTENTIAL DESIGN I:1PROVEMENTS ARE CURRENTLY BEING STUDIED,.
IN THE NEAR TERM WE EXPECT-TO RECCIO!END DESIGN IMPRCVEMENTS WHICH DO NOT AFFECT OTHER PLANT SYSTEMS OR RECUIRE EXTENSIVE ANALYSIS TO IMPRCVE CPERATOR PERFCE 1A2 ICE DURING TRANSIENTS SIMILAR TMI-2.
IN THIS CATEGORY ARE SUCH THINGS AS:
MOPZ POSITIVE INDICATICN OF PILOT OPERATED RELIEF VALVE PCSITICN; AN :NTERI.CCK THAT UOULD ISOLATE CERTAIN CONTAINMENT PENETRATIONS INCLUDING THE CCNTAINMENT SUMP UPON EMERGENCY CORE CCOLING SYSTE 1 ACTUATICN; AlD INSTRUMENTATICN WHICH WILL INDICATE TO THE OPERATOR WHETHER THE P2 ACTOR CCOLANT IS APPROACHING "HE SATURATED CONDITICN WITHCUT HIS HAVING TO CONSULT STEAM TA3LES OR CURVES.
WE ANTICIPATE THAT RECOM:1ENDATICNS OF THIS TYPE WILL BE MADE WITHIN SIX WEEES.
IMPLEMENTATICN WCULD BE POSSI3LE CURING ALMOST MIY CUTAGE.
WE ARE ALSO REVIEWING THE IMPLICATION CF THESE DESIGN IMPROVEMENTS FCR OTHER B&W 145, 177 AND 205 FUEL ASSEMBLY PLMITS NCW 3EING DESIGNED RID CONSTRUCTED.
4.
I HAVE APPOINTED A SPECIAL TASK FORCE TO ADVISE ME WITHIN THREE MCNTHS CCNCEP2 LING OTHER IMPLICATIONS FOR PLANT DESIGN AS A RESULT CF THE TMI-2 INCIDENT.
THE CHARTER OF THIS TASK FORCE IS lide 7 SHCWN CN THE NEXT OVERHEAD.
THIS TASK FORCE IS CCMPRISED OF A hl~..er DIVERSE GRCUP OF TECH'IICE PERSCNNEL SCSI WITHIN THE NUCLEAR POWER GENERATION DIVISICN MID FRCM CTHER DIVISICNS.
i68 105
C.
LONGER-TEPli ACTIONS SEYCND THE DiMEDIATE-AND NEAR-TERM ACTICNS, LCNGER-TERM ACTIONS WILL SE UNDERTAKEN.
THE ACRS HAS RECC201 ENDED A MAJOR RE-ANALYSIS EFFCRT CN TRANSIENTS IN PPISSURIIED WATER REACTORS THAT INVOLVE INITIALLY, OR AT SCME TIME DURING THEIR CCURSE, A S 1ALL 3 REAR IN THE PRDIARY SYSTEM, AND EXPRESSID ITS BELIEF THAT THE TMI-2 INCIDE'IT HAS,.
AND THESE ANALYSES WILL, DE21CNSTRATE THAT ADDITICNAL INFOPJ1ATION REGARDING THE STATUS OF THE SYSTEM WILL BE NEEDED IN ORDER FOR THE PLANT OPERATOR TO FOLLOW THE CCURSE OF AN ACCIDENT AND THUS BE ASLE TO R.ESPOND IN Ali APPRCPRIATE MANNER.
ALTHCCGH WE AGPIE THAT THE TMI-2 niCIDENT HAS SHOWN A NEED TO CCNSIDER, ON SCTH A NEAR AND LCNG-TERM BASIS, THE FEASIBILITY AND DESIRABILITY OF POTENTIAL DESIGN MOD!?!CATICNS TO IMPROVE THE niFOP2dATION AVAILA3LE TO OPERATORS, WE DO NOT BELIEVE THAT fiAJOR P2-ANALYSIS IS NECESSARY FOR THESE NEAR AND LONGER TERM DESIGN DECISIONS.
AT THIS JUNCTURE, WE I'iTEND TO UNDERTAKE A PIVIEW OF TECSE ANTICIPATED TRANSIENTS NHICH RESULT IN THE OPENING OF THE PILOT CPERATEJ FILIEF VALVE TO CONFIRM
" FAT AN CPEN PILCT OPERATED RELIEF VALVE I'.. CCNJUNCTION UITH ANTICIPATED TRANSIENTS IS CCVEPID BY EXISTING SMALL 3REAK ANALYSIS.
IF THESE REVIEWS, CUR OWN AND THE NRC STAFF'S CNGOING REVIEWS CF THE TMI-2 INCIDENT, AND OCR PLANNED EFFORTS TO ASSESS PRCPOSED NEAR AND LCNGER TEP24 MCDIFICATICNS SHOULD INDICATE A NEED FOR ADDITICNAL ANALYSES, WE WILL PRCf1PTLY CNDERTARE TO PERFCR21 THDi.
WITH RESPECT TO FURTHER CRITERIA FOR DESIGN MCDIFICATIONS BEYOND THAT BEING I '24EDIATELY ADDRESSED, WE WILL BE EXAMINING SUCH CTHER CRITERIA, BUT WITH THE CAVEAT THAT EACH MUST BE 168 106 -
CAREFULLY EVALUATED WITH REFECT TO ANY IMPACT CN OTHER DESIGN
-. REQUIRE?INTS.
WITHIN THIS AREA, WE WILL CONSIDER THE MERITS OF REACTOR VESSEL FLUID LEVEL INDICATICN INSTRUMENTATICN AND REACTOR TRIP IN LCSS OF FEEDWATER FLCW.
MCRE EXTENSIVE CCNSIDERATICN WILL BE GIVEN TO CONTAINMCiT ISOLATION UPON ACTUATICN OF THE EM2RGDICY CORE CCOLING SYSTEM TO PARTICULARLY REVIEW WHICH SYSTEMS SHOULD BE ISOLATED AND WHICH SHOULD BE MAINTAINED AS NECESSARY TO CiHANCE PLANT SAFETY.
AN ADDITICNAL DIRECTION FOR CCNSIDERATICN OF FURTHER CRITERIA INVOLVES RECOVERY FROM THE MITIGATICN OF TRANSICITS.
CBVIOUSLY, PREVENTICN IS NOW, AS BEFORE, THE FOREMC ' GOAL OF DESIGN BUT CCNSIDERATICN WILL BE GIVEN TO SUCH ITEMS (S ISOLATED AND SHIELDED LCNG-TERM DECAY HEAT CCOLING, REACTOR VESSEL VENTING, MORE FORMALI::ED STRUCTURE AND PROCEDURES FOR CCMMUNICA-TION BETWEEN THE SITE MID OUTSIDE SUPPORT, AND HMIDLING OF HYDROGEN GENERATICN.
III. CCNCI.USION IN CONCLUSION, IT IS B&W'S VIEW THAT:
THE B&W DESIGNED PLKITS CAN BE CPERATED SAFELY.
o THE SEVERI'"Y CF TMI-2 INCIDENT WMutANTS RE-EMPHASIS OF:
o NEAR-TERM UPGRADING OF ADMINISTRATIVE CCNTROLS AND LCNGER-TERM CONSIDERATION OF SYSTEM MODIFICATICNS TO PROVICE ADDITIONAL ASSURANCE THAT SAFETY SYSTEMS WILL BE AVAILABLE ON DEMAND.
NEAR-TERM OPERATOR TRAINING AND INSTRUCTIONS, AND LCNGER-TERM CCNSIDERATICN OF SYSTEM MCDIFICATICNS TO PROVIDE ADDITICNAL ASSURANCE THAT THE OPERATOR WILL RECCGNIIE THE IMPORTANCE OF MAINTAINING SUBCCCLED LCOP CONDITICNS AND CORE COOLING CAPA3ILI'""? FOR A BROAD SPECTRUM OF TRMISIENT CONDIT!CNS.
168 107
IN RESPO:ISE TO TIIE TMI-2 I:iCIDENT, B&W HAS:
EXPENDED MAJCR PRIORITY EFFORTS TO SUPPORT /CID ASSIST THE LICENSEE ni BRINGING TMI-2 TO A COLD SHUTCOWN CCNDITICN.
T7 DEN DD1EDIATE ACTICN TO REVIEW THE UTCIDENT WITH OPERATORS OF B&W PL1d1TS, ISSUE INSTRUCTIONS AND ADVISORIES TO OPERATORS OF S&W PLANTS, IdID TO PROVIDE SUPPORT MiD ASSISTANCE TQ OPERATORS OF B&W PLtdiTS, ALL WITH A VIEW TO ASSURING THAT DiCIDENTS SIMILAR TO TMI-2 WILL NOT RECUR.
UNDERTAKEN EFFORTS TO CONTINUE ITS REVIEW-OF THE INCIDENT /diD REVISE AND UPDATE DISTRUCTICNS MID ADVISORIES AS NECESSARY, MID TO DiPLDIENT AN OPERATOR TRAEFNG PRCGRAM WITH SPECIFIC REFERENCE TO THE TMI-2 INCIDENT.
IMPLDIENTED EFFORTS TO EVALUATE PCTINTIAL NEAR-TERM DESIGN MODIFICATICNS', WHICH CO NOT OTHERWISE IMPACT OTHER ELDIENTS QF PLtdlT SAFETY, WITH A VIEW TCWARD PROVIDING FURTHER ASS.UPASCE AGAINST RECURRENCE OF INCIDENTS SDi!LAR TO TFI-2.
DEVELOPED PL; dis FOR CCNSIDERATICN OF LONGER-TEPoi IMPROVEMENTS IN THE CAPASILITY OF B&W PLANTS TO PREVENT, MITIGATE, MID RECOVER FRCM INCIDENTS SIMILAR TO TMI-2, 168 108 WHILE THE TMI-2 INCIDENT WAS SERICUS, WE 3ELIEVE THAT THERE ARE CCNSTRUCTIVE LESSONS TO 3E LEARNED AND THAT TIMELY, RESPCNSIVE ACTIONS HAVE BEIN TAKEN TO ASSURE THE SAFE CPERATlCN OF B&W REACTORS.
WE BELIEVE THAT THE ADDITIONAL ACTIONS WHICH I HAVE OUTLINED TODAY
- iILL FURTHER E:iHANCE THAT SAFE OPERATION IN CLOSING, LET ME EMPHASIIE THAT WE WILL REMAIN CPEN TO ANY SUGGESTICNS THAT THE CCMMITTEE MIGHT HAVE AT THIS TIME, AND AS THE RESULTS OF CUR NEAR AND LCNG-TERM ACTICNS SECCME AVAILABLE.
IN THE MEANTIME, WE WILL ENDEAVOR TO KEEP THE CCMMIMEE AND THE NRC ADVISED AT EACH SIGNIFICANT JUNCTURE IN OUR EFFORTS.
I w
168 109 e-
h, ROM DECAY HEAT REMOVAL COOLERS PRIMARY SYSTEM F
_ww
's---- H I4 RE EF - "k]'
"O D""'" I"""
Y
.-l-To ac DRAIN PUMP VALVE t-g C4-H PRESSURIZEN g
FLOOD TANK ~
(1)
STEAM STEAM STEAM 2-GENERATOR
^
REACTOR VESSEL F E EDWA T E R - --C
- Q 4_b =-- d_A
]
O-FEEDWA TER
-.J
'(
I to OH sysitM s->
bI w>
(j runt MOT 04
- _Nk, f ROM HIGH st AL RETURN *-
3 t.t a N PRissunt
~3 p
-NN ]
L__ !
IN JEC T M)N RC PuuP vi st -i ruMrs s '-N #4-(T YPIC AL)
VL----
-1 iROts M ANEUP CONTROL VALVE to yo l
LET DOWN COOLERS
. * * ~
CO M
i
NUCLEAR STEAM SYSTEM D
Q&
=
LEV L SENSING AUX FEEDwATER 40ZZLE M
l
}
f FEEDwATER g-N0ZZLE 1
s f
- (
$ URGE LINE e
x R
p N0ZZLE
-- d LEVEL SENSING O
q-Q g <u,,
, -E 9
~
K i X,a 5
ah 0
(a a
e a
)
'y
/
\\
1 168 111 9
,I O = e 4p
_ l i
t i
e e
f
-a owee TI
\\'
/
l1 s
5 g
w
=
.g I
I l
O
- !r
<A 9 %W
.O ii l 7
Q I
T I%
~
Y,el
- i7 ffl I.,
5., =
i 3
2
~.e I
I ee I
- l i
i
. p:7
=
.t.
/
1
~
og l
l. 7 llE I
T! Y I
w
.s I
s 5:
7 9I i
i 7
7 m
n y
i 30 E
i 1 -
et j
4 m
_ =
D C ! !.
7 7
_j T I
e:
e m
C 4 4 y
3 Z
i e * -
L A :
o J0 I
l i = ":
=
o V:
- I 9 '
l l
- 8:
w y0 I$
M
- I 23 O h D3 :
L y
sa sa Ti Ias=
i 3:2
- a t
=
I l
l 7
'D 95 =r Mq 7 gs 1
1
,1, 8.2 m
r
+
78 7
T
~
i i
-a i
i 7
- 3 M"
Y l
4
+
.T
=2
.=!
A aa 4
==
i.
-l: r 3
4
,o-
$2 x !; -
N 2
' ~ 0,- :d a
>+, -C,
- ~
g
~
m +
! n*,.i a zk.b, :
E l4 3
71 5
o 168 112 e
G G
SIX SIGNIFICANT FACTORS e
DELAYED AUXILIARY FEED' DATER o
PILOT-OPERATED PRESSURIZER RELIEF VALVE NOT RESEATING AND LACK OF RECOGNITI0tl 0F THIS EVENT SECURING HIGH PRESSURE INJ_ECTION PREMATURELY.
e e
CONTAINMENT ISOLATION o
INAPPROPRIATE EMPHASIS ON PRESSU31ZER LEVEL INDICATION e
SECURING REACTOR C00LAtli PUMPS e
h 168 113 9
PRIi!CIPLES FOR C0ilSIDERIllG FUTURE ACTIOilS e
ASSURANCE THAT SYSTEMS IMPORTAllT TO SAFETY ARE AVAILABLE e
FOCUS ON FUtlDAMENTAL PHYSICAL PROCESSES WHICH ASSURE CORE COOLING
~ ~
~
e CONSIDER ALL ACTIONS IN THE C0ilTEXT OF TOTAL PLANT SAFETY O
168 114 69 e
=
ym 6
e6eee
TMI-2 INCIDEllT TRAIi1ING
,9 SCOPE DISCUSSION OF TMI-2 TRANSlENT SIMULATOR DEM0i!STPATION HANDS-ON OPERATOR INCIDEUT RECOVERY TRAIN-ING ALL REACTOR OPERATORS DURATION 1 DAY i
START DATE APRIL 9, 1979 I
e o
e 168 115 e
TMI-2 OCCURREilCE - TECHNICAL REVIEW COMMITTEE CHARTER e
REVIEN TECHHICAL ASPECTS OF THE TMI-2 OCCURRENCE o
DEVELOP REC 0i"'ENDATI0flS FOR EQUIPMENT IMPROVEMEilTS, OPEPATOR INTERFACE, RECOVERY REQUIREMENTS AND INCIDENT SUPPORT, e
ASSESS IMPACT OF THE TMI-2 OCCURRENCE AND POTENTIAL RESULTING CHANGES IN REGULATORY REQUIREF:ENTS ON NUCLEAR POWER GENEPATION DIVISION TECHNICAL ACTIVITIES.
m m
9 168 116 ga me
CONTENTS OF ACRS DRAFT LETTER (As reaa co NRC Commissioners on 4/17/79)
Natural circulation is an important mode of reactor cooling, both as a planned process and as a process that may be used under abnormal circumstances. The Ccamittee believes that greater understanding of this mode of cooling is required and that detailed analyses should be developed by licensees and their suppliers. The analyses should be supported, as necessary, by experiment. Procedures should be developed for initiating natural circulation in a safe manner and for provid-ing the operator with assurance that circulation has, in fact, been established. This may require installation of instrumentation to measure or indicate flow at low water velocity.
The use of natural circulation for decay heat removal following a loss of off-site power sources requires the maintenance of a suit-able overpressure on the reactor coolant system. This overpressure may be assured by placing the pressurizer heaters on a qualified on-site power source with a suitable arrangement of heaters and power distribution to provide redundant capability. Presently operating PWR plants should be surveyed expeditiously to determine whether such arrancarents can be provided to assure this aspect of natural cir-culati capability.
The plant operator should be adequately informed at all times concerning the conditions of reactor coolant system operation which might affect a capability to place the system in the natural cir;;ud 11/_
g m--
N-*
Mu ee eme-w - * * - - -
tion mode of operation or to sustain such a mode.
Of particular importance is that information which might indicate that the reactor coolant system is approaching the saturation pressure corresponding to the core exit temperature. This impending loss of system over-pressure will signal to the operator a possible loss of natural circula-tion capability. Such a warning may be derived from pressurizer pres-sure instruments and hot leg temperatures in conjunction with con-ventional steam tables. A suitable display of this information should be provided to the plant operator at all times.
In addition, considera-tion should be given to the use of fuel exit temperatures from the fuel subassemblies, where available, as an additional indication of natural circulation.
The exit temperature of coolant from the core is currently measured by thermocouples in many PWR's to determine core perfor-mance. The Committee recommends that these temperature measure-ments, as currentiv available, be used to guide the operator concern-ing core status. The range of the information displayed and recorded should include the full capability of the thernacouples.
It is also recommended that other existing instrumentation be examined for its possible use in assisting operating action during a transient.
The ACRS recommends that operating power reacters receive priority with regard to the definition and implementation of instrumentation which provides additional information to help diagnose and follow the course of a sericus ac:ident. This should include improved sampling 168 118
-hne
-e e.
p,e og -
wMe g
_m e*
3-procedures under accident conditior.s, and techniques to help provide improved guidance to offsite authorities, should this be needed. The Committee recommends that a phased implementation approached be employed so that techniques can be adopted shortly after they are judged to be appropriate.
The ACRS recommends that a high priority be placed on the develop-ment and implementation of safety research on the behavior of light water reactors during anomalous transients. The NRC may find it appropriate to develop a capability to simulate a wide range of postu-lated transient and accident conditions in order to gain increased in-sight into measures which can be taken to improve reactor safety. The ACRS wishes to reiterate its pret ious recommendations that a high priority be given to research to improve reactor safety.
Consideration should be given to the desirability of additional equipment status monitoring on various engineered safeguards features and their supporting services to help assure their availability at all times.
The ACRS is continuing its review of the implications of this accident and will provide further advice as it is developed.
168 119 e
w em e
---