ML19206B247
| ML19206B247 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/09/1977 |
| From: | Herbein J Metropolitan Edison Co |
| To: | Grier B NRC Office of Inspection & Enforcement (IE Region I) |
| Shared Package | |
| ML19206B246 | List: |
| References | |
| GQL 1044, GQL-1044, NUDOCS 7905080169 | |
| Download: ML19206B247 (2) | |
Text
.
A
\\
.r q
W S jf 2 1, 2,,
-f
?/ =
_m l METROPOLITAN EDISON COMPAN SUBSICIARY OF GE VERAUUBUC UDUMES cCRPORA T!ON TELEPHONE 215 - 923-3601 GT OFFICE BOX 542 REACING PENNSYLVANIA 196c3 August 9, 1977 GQL 10hh Mr. 3. 5. Grier, Director U. S. Nuclear Regulatory C~"d ssica Office ~cf Inspectica & Inforcement Region I 631 Park Avenue King of Prussia, Pennsylvania 19hC6
Dear Sir:
Three Mile Island Nuclear Station Unit 2 (TMI-2)
License No. C??S-66 Dcchet No. 50-320 Reacter Ccolant,Purp Seal Failure ?ctential C~ 4 Following Less of Offsite ?cver Cn July 1,1977, Mr. Lcu Narrev and Mr. '2. Rebelevski of your office were verbally nctified of a situatics which Metrcpolitan Ediscn Cc=pany censidered
=ay be repcrtable in,ccordance with the require =ents of ICCFR50.55(e).
This letter constitutes the required thirty-day fellev-up letter and is su'. itted late per cur letter of August 1,1977 Descrittien The Reactor Ccolant (RC) pressure boundary along each RC pu=p shaft censists of three face seals. 'Ihro =eans are e=plcyed to provide ecoling to the RC pu=p seals.
Cne =eans, seal injecticn, provides cooling by passing RC =ake-up water along the pu=p shaft and into the RC syste= preventing het reacter coolant frc= passing upward thrcugh the shaft seal sys,e=.
fhe seccnd =eans Fesctor of ecoling is provided by the inte. ediate c1csed cooling vater.
ecolant is recirculated by an edidary impeller en the RC pu p shaft and eccled by an auxiliary heat exchanger cennected to each RC pu=p.
This seccnd syste= provides adequate cooling for the seal syste= provided the RC pu.p is r"-nd g.
Either of these two syste=s alene vd provide viequate protection fcr the pu=p seals during ncr=al cperations.
If both seal eccling systems becc=e incperable, the possibility exists for the RC syste= pressure to force hot reacter ecclant upward along the RC pu=p
'"he rate at which 3 shaft and cut the seal leakoff and/cr seal --+"
'd es.
G i.) this cccurs is dependent upcn the RC syste= pressure and the initial condi-v' tiens of the seal faces. The heat tr-d **ed to the RC pu=p shaft sleeve and seal rings during the passage of reacter ecolant creates the a1 stresses
- '2 7905080/[9 S
c,
~
e Mr. 3. E. Orier 2
August 9, 1977 GQL 1Chh sufficiently large to cause the seal rings to fail when uey reach a te=perature of approxi=ately 2kOc F.
As a result, all three seal rings in ene RC pu=p can fail, a=d the resulting leakage frem that pa=p cculd be as =uch as 150 g;:n.
Analvsis of Safe *r_T=rlicatice Fc11cving a less of offsite pcver, ecoling accc=plished by i=peller recircu-latien is lost due to the less of RC pu=p rctation.
The ecoling of the seals then becc=es dependent en the culy re a ning ecoling systes; the seal d
injection syste=.
The seal 1:Jectica systen vill provide adequate ecoling folleving the 1 css of offsite pcver if the =akeup pu=p aligned fer ner-
-^eup service starts as requirei. The =akeup pu=p, which receives pcVer frc= an e=ergency diesel generater, is sequenced to sta-t, cc=e up to speed, and previde adequate seal injectica flev to all fcur reacter ecolant pu=ps within approv' tely 30 seconds. Any one of the folleving single failures: 1) failure of the isciaticn valve (MU-7378) in tue seal inj ectica line, 2) failure of the flow centrol valve (MU-V32) in the seal 1 Jection line, 3) failure of the diesel providing pcver to the two makeup Fa=ps.sup-plying seal injecticn; in ec=binatica vith the 1 css cf offsite power veuld result in a less of bcth seal eccling systems. This in turn eculd lead to p.} RC pu=p seal failures and possible reacter ecolant leakage in excess of the
-r -, *
- g =e.keup' (EFI) pu=p cspacity.
The event described above veuld be classified as a s=all break 1 css of ecci'-t accident. The results of this accile.nt have been presented and referenced in the FSAR, Chapters 6 and 15
- he resultant effect of this event en the health and safety af the general public is as reported in the FSAR.
Cer etive Actics Tc eld dmte the possibility of a loss of seal injection, the design vill be =cdified to previde tvo separate, safety-grade scurces of water to the aed i=J ecticn header. This =cdificatica vill provide a single failure-prcof seal injection supply to the reacter ecolant pr=ps felleving a less of offsite pcver. The =cdification vill te described fally in the appro-prtate secticns of the FSAR. Plant modifications vill be ec=pited prior to initial f2el lead.
Very trul7 7 curs, t
wat
. G. Hersein JGH:JRS:-
Vice President rx. -
cc:
Dr. Ernst Volgenau, Director qG $
Office of Inspecticn & E=forcement n,
U. S. Nuclear Regulatcry C d ssics L. a t-Washington, D. C.
20555
-..