ML19220A816
| ML19220A816 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 09/02/1976 |
| From: | Arnold R Metropolitan Edison Co |
| To: | O'Reilly J NRC Office of Inspection & Enforcement (IE Region II) |
| References | |
| GQL-1258, NUDOCS 7904250001 | |
| Download: ML19220A816 (3) | |
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METRCPOLITAN EDISON COMPANY susvorm cf as.venat pu3 tic uritiries cas?cazric.i
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PCST OFFICE DOX 542 REACING, PENNSYLVANI A 19Cc3 TELEPHONE 215 - 020 C001 Se,ruc=ber 2,1970 m: 12P Mr. J. P. O'Reilly, Director Office of Inspection and Enforce:ent, Regicn 1 s
U. S. Nuclear Regulatory Co ission 631 Park Avenue King of Prussia, Pennsylvania 19406
Dear Mr. O'Reilly:
Subject:
Three Mile Island Nucicar Station Unit 2, Docket No. 50-320 Response Tine On August 3, 1976, Mr. L. Narrow of your office was verbally notified of a situation which Metropolitan Edison Company considered to be reportable in accordance with the require =ents of 10CR50.55(a).
This letter constitutes the required thirty-day follow-up letter.
Descriotion Cathering infor=ation on required and expected Engineered Safety Features response ti=es during the preparation of the response ti=e test progra= revealed that several of the expected response tines (based on vendor test data, diesel loading sequence, etc.) were in excess of the required ti=es established by FSAR analyses or other considerations.
See attached Table I.
Analysis of Safetv Irelications If the discrepancies in the rec;uired versus expected response times had re=ained undetected, and if a LCCA coupled with a total loss of offsite power had occurred, the consequences of nuch an acci-dent conceivably could have exceeded those consequences of this accident as calculated in the plant safety analysis, however, preliminary evaluation indicates that the effect would be slight, adding only about 0.3 psi to the calculated peak contain=ent pressure, and would thus have produced only a s=all increase in the effect of such an accident on the health or safety of the public or the plant staff.
Corrective Action 1.
The single centain=ent isolation valve having a closing time in excess of one =inute is in series with a second isolation valve in the sa=e line with a closing time of 31 seconds.
Since the line is in a closed system, built to AST:. Code Section III 10'059 C 0968 7904enoa!
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Mr. J. P. O'Reilly GQL 1258 U.S. Nuclear Regulatory Coc=1ssieu Page 2 standards and seis=ically supported, the effects of this slow valve closure are considered to have an insignificant effect on the overall leckage from the ccutain= cat following a LOCA.
Thereforc, no changes are considered necessary for this valve.
2.
The diesel loading sequence for the high pressure and low pressure injection pu=ps will be revised to ensure that these pumps will be delivering rated flow in less than the 25 seconds assumed in the safety analyscc.
3.
The diesel loading sequence and pu=p electrical logic will be reviscd to enable the reactor building fans and cooling water to be started as early as possible consistent with other i
requirements. However, the 35 second response time assumed in the safety analysis will be extended to be consistent with the revised expected response tine for this system. A new reactor building pressure analysis will be done which, by pre-lbhry evaluation will cause only a s=all increase in the calculated peak pressure, from 55.7 psig to about 56.0 psig, l
which is still below the design pressure of 60 psig.
4.
Since the required response ti=e for the Nuclear Service River Water System is based on supporting the startup of the Reacter Building E=ergency Cooling Booster Pu=ps (see ite 3 above), the required response time will be revised to be con-i sistent with the ti=e requirements for these booster pu=ps.
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l Perfor=ance of the response tiae test progran prior to initial fuel l
loading will provide additional assurance of the satisfactory resolutien of the noted discrepancies.
i Very truly yours, Signd - R. C. ArncM R. C. Arnold Vice President RCA:CWS:=ft Attachment i
Dr. Ernst Vol6enau, Director 00:
Cffice cf ins?ection and Enforcement U.S. Nuclear Regulatory Cc==ission
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Washington, D.C.
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At tacl:uent TABLE I ESF Response Tina Discrepancies System Exceeted Tine Recuired Time i
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1.
Reactor Euilding Isolation 65 seconds 60 seconds f
2.
High Pressure Injection 26.4 seconds 25 seconds Low Pressure Injection 30.4 seconds 25 seconds 3.
Reactor Building Emergency Cooling Fans 39 seconds 35 seconds l
Cooling 'n'ater 126 seconds 35 seconds 4.
Nuclear Services River Water 81.4 seconds
- 10 seconds
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- = 3ased on LOCA with nor=al power available. All other ti=es are based on loss of offsite power.
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