ML19340A942
| ML19340A942 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/12/1975 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19340A939 | List: |
| References | |
| NUDOCS 8009100771 | |
| Download: ML19340A942 (2) | |
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U flit E C STATES fo U C L E A R REGULATORY C O fA M IS SI O rd W AS HINGTO N D. C. 20 5 5 5 9
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATIC" SUPPORTING A'RND:ENT NO.11 TO FACILITY LICENSE '.'0. DF2-2 Cl!ANGE NO. 30 TO TECH':'ICAL SFECIFICATIO."E C0""03lEALTH EDIS0" CC"PANY DRESDEN 'n: CLEAR POSR STATIO" ls'IT 1 DOCKET NO. S0-10 INTRODUCTION By letter dated December 3, 1974, Corenvealth Edison (CE) recuested changes to the Technical Specifications appended to Facility Operating License No. DPR-2 for Dresden Nuclear Po. er Station Unit 1.
The uronosed changes add interin operability recuirenents for the primary reactor'
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feedwater systems.
DI SCUSS10::
At Dresden Unit 1, at least one of the three prirary reactor feedwater punps nust continue to operate through a Loss of Coolant Accident (LOCA) involving a small to interr.ediate size pipe break to assure that peal clad temperatures renain below 2300*F as recuired by the Co m ission's Interin Acceptance Criteria (IAC).
However, CE has proposed to install a high pressure coolant injection system (HPCI) that will eliainate the Dresden Unit I reliance on the feedwater systen to meet the IAC.
in the interin period, prior to installation of the EPCI systen, CE has preposed a node of operation thr.t rec;uires one ;*irary fecc' water pump to be epcrable.
This pu:;p notor will be powered from At:xiliary Pcxer Transformer No. 12 which is supplied directly fre effsite pcxer.
E'iA L'JATIO" The onsite power recuirerents for the Dresden Unit I vital leads are supplied by
.o 10,000/12,000 kva auxiliary perer transformers.
One trar.3forner, TR-12, is connected to the CE 13S kV transmissien systen.
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. The other auxilf ary power transformer, TR-11, is connected to the Unit 1 generator terminals.
In the event that the output of either of the two auxiliary transformers is lost, low voltage relays autonatically transfer the effected equipment bus to the remaining transforner.
Requiring that at least one prinary feedwater pump be operable and powered from transformer TR-12 assures that in the event of a loss of transformer TR-11, which is connected to the Dresden Unit I generator terminals, ak least one primary feedwater pump will be operable and continuously powered by offsite power without reliance on automatic transfer to transformer TR-12.
The proposed Technical Specifications also require that the emergency feedwater pump be operable during reactor power operation with reactor pressure greater than 140 psig. The operability of this pump will assure that in the unlikely event of loss of both transformers TR-11 and TR-12 that the emergency feedwater pump can supply up to 100 gpm at 1200 psig to the reactor vessel from the 50,000 gallon condensate storage tank.
The licensee has also proposed to add two new surveillance requirements to verify the operability and source of power of the feedwater system daily, and the operability of the emergency feedwater pump nonthly.
These surveillance intervals are adequate to assure the operability of these systems.
These changes to the Technical Specifications do not require any modifi-
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cations to the reactor or to the reactor operational procedures. They are administrative in nature and operation in confornity with these revised specifications will provide added assurance that the Dresden 1 peak clad temperatures will not exceed 2300*F as a result of a loss of coolant accident before the HPCI system is installed.
CONCLUSION 3ased on the considerations discussed in our evaluation, ce have concluded that:
(1) because the change does not involve a significant increase in the probability or consequences of accidents previously considered and does not involve a significant decrease in a safety nargin, the change does not involve a significant hazards considerntion, (2) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed canner, and (3) such activities will be conducted in compliance with the Connissien's regula-tions and the issuance of this anendaent will not he inirical to the connon defense and security or to the health and safety of the public.
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