ML19308C822
| ML19308C822 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 02/08/1978 |
| From: | Creitz W METROPOLITAN EDISON CO. |
| To: | Varga S Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19308C823 | List: |
| References | |
| TASK-TF, TASK-TMR GQL-0211, GQL-211, NUDOCS 8002070573 | |
| Download: ML19308C822 (2) | |
Text
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MMit PGA NQGR/33 METHOPOLITAN EDISON COMPANY POST OFFICE Box 542 READING, PENNSYLV ANI A 19603 TELEPHONE 215 - 929-0601 February 8, 1978 GQL 0211 i....
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Director of Nuclear Reactor Regulation
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Mr. Steven A. Yarga, Chief
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Lisht Water Reactors 3 ranch No. k U. S. Nuclear Regulatory C - 4ssion FES, ;'/: :3w
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Washington, D.C.
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Dear Sir:
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Three Mile Island Nuclear Station Unit 2 (TMI--20i ! '.6
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License No. CPC'l-66 Docket No. 50-320 Additienal Ites Which Will Not be Cc=pleted Prior to Puel Load
,,, _m.c a My letter to you on January 25J1?TS described items which vculd not be co=pleted prior to 'initialufttel'lc~ading of TMI-2.
At that time ve anticipated
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that there vould be no incenplete construction items which would otherwise be required for fael load. Since that time ve have identified one ite= vhich vill not be ec=plete. The inter =ediate closed cooling vater heat exchangers
(!C-C-1A/3) are supposed to be designed as Seis=ic Category I cc=tonents. Due to a ec==unications difficulty between the parties involved in the design, this work vill not be ec=pleted for at least one conth. Please note chat the TMI-2 FSAR describes these ec=ponents as non-seis=ic Category I.
The coolers were upgraded as a result of a~=oderate energv pipe break survey conducted in the plant approx 1=ately two years ago. However, the FSAR could not be updated until the design work had been ec=pleted, as reqaired by the Met-Ed Qaality Assurance Program.
Verv truly ycurs, eh
j W. M. C.
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President WMC:CWS:tas Attach =ent
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The inter =ediate closed cooling vater heat exchangers (IC-C-1A/3) are provided with cooling water fran the nuclear services river water syste=, which is a seismic Category 1 systen. Due to the essential services supplied the NSRW systen, any impair =ent of flev has a potential for affecting plant safety. Since the internediate closed cooling water system interfaces with the NSRW system, there are two potential safety concerns.
First, failure of the cooler as a result of a seismic event could result in flooding da= age to various safety related equip =ent located at the south end of the auxiliary building, at elevations 305 ft., 280 5 ft., and 258 ft; second, under certain operating conditions, the loss of cooler integrity could result in redaced flow to co=ponents essential to safety.
The river water syste= in the vicinity of the ICCN heat exchangers consists of one 3 inch dia=eter supply line from each redundant river water header with ES actuated river water valves (NR-V51A/3) for cooler isolation.
From the supply line upstream of the isolation valve, a backvash supply line with =anual isolation (NR-V52A/3) connects to the cooler discharge, which is a single cross-connection between the automatic isolation valve and cooler inlet providing a path for discharge of river water during backvashing operation.
Due to the lov frequency of backvashing, this path is =anually controlled. In the backvashing =ede, a seismically induced cooler failure could result in excessive demand on the river water systen and consequent reduction in flow to essential co=ponents.
A seismic failure under any operating condition (i.e. not only during backwashing) could discharge water to the auxiliary building from the discharge lines at flow-rates sufficient to create a potential flooding ha:ard.
The cooler location is in close proxi=ity to an open stairvell leading to the building lover level in the vicinity of the reactor building emergency cooling booster pu=ps and the decay heat re= oval punps.
Due to the ccnditions described above, the design of the coolers was changed to seismic Categerv I approximately two years ago. The analysis of the seis=ic design conditions is nearly co=plete and indicates a require =ent for no::le bracing and reinforcement of the heat exchanger support saddle design.
If additional structural support is required, it vill be provided between the existing structural supports and the building south wall approxi=ately three feet from the structure.
Delay of this work beyond the TMI-2 fuel load dhte does not represent a substantial risk to the health and safety of the public. First, the probability of a large earthquake in the area within the next several months is extre=ely 1.ov.
- Second, the consequences of an accident during this ti=e fra=e are inconseq,uential because there is not a significant fission product inventory available for release.
Finally, should such an event occur, =anual actions could be taken to isolate the ICC cooler.
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