ML19257E274
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DJI TRIBUTION:
FEB 2 81980 vCENTRAL FILE NRR READING EBXXE AS3 READING MEMORANDUM F0Et: Harley Silver, Project Manager THI-1 Restart FROM:
Jared Wemiel:
Auxiliary Systems Branch, DSS THRU:
Gerald Mazetis, Section Leader ReactorsSystems Branch, DSS
SUBJECT:
THI-l RESTART REVIEW, AUTOMATIC INITIATION OF EMERGENCY FEEDWATER (EFW)
As part of the restart requirements included in the Order for THI-1, Met-Ed is required to 1@lement Short Term Lessons Learned. NUREG-0578 prior to restart. P,ecently issued Orders to all operating PWR licensees (except Met-Ed) exempt them from compliance with Lessons Learned item 2.1.7.a.
Automatic Initiation of Auxiliary Feedwater. No schedule for its implemen-tation has been established. Since Met-Ed t.id not receive this notifica-tion, we nave assumed that they are tequired % implement the short term requiremnts of 2.1.7.a prior to mstart.
Requirement 2 of item 2.1.7.a specifically states that automatic EFW initia-tion snall meet the single failure critorion to prevent loss of system function. Met-Ed has committed to provide single failure proof auto initia-tion signals for EFW pump actuation prior to restart. However, the staff interpretation of " system function" includes automatic opening of the EFW contml valves. This interpretation presents a problem to THI-l (and a number of other B&W plants) in that EFW system flow control is provided through the Integrated Control System (ICS) which is subject to single failures that could prevent automatic delivery of feedwater even if the EFW pugs are properly actuated.
Met-Ed has comitted to eventually upgrade the EFW system to meet all safety grade requirements and eliminate the ICS dependency of the EFW control valves.
However, this modification involves procurement of certain long lead time equipment (nuclear class valves and instrumentation) and Met-Ed states that the equipment cannot be installed prior to the presently projected restart date. They indicate that delivery and installation of these items is not expected before mid-1981. The licensee propopes, therefore, to install the safety grade system modifications 44 the first refueling outage after restart.
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DATEk Nac ronu sie a r6) Nacu o.no c u.s. cov enNMENT PRINTING OFFICE : 1979-289-369
FEB 2 g 880 Harley Silver
-2 In the interim. Het-Ed has stated in the Restart Report that they will make certain procedural and hardware modifications to enhance EFW system reliability prior to restart. These modifications include the addition of a de powered manual backup EP.4 control valse operating station in the control room fully independent of ICS (although steam generator level indication is not separated from ICS). This station enhances operator capability to contml EFW flow in the event of an ICS fails re. Plant operating and emergency procedures have been revised to instruct the operator en use of this new manual station. To further ehhance system availability, a backup air compressor powered from vital busses and a passive air. peservoir have been added to assure airssupply to the flow control valves, and thereby provide the capability to modulate them as necessary.
In addition, recently approved analyses by B&W indicates that a 20 minute delay in EFW initiation in B&W plants including TMI-1 will not compromise core cooling capability. This time would allow an operator to assume local manual control (outside the control room) of EPd at the valves if needed.
With the licensee's stated schedule problems, it appears that delay in restart is inninent unless relief from 2.1.7.a is allowed. A decision on applicability to TMI-1 of the previous exemptions to 2.1.7.a is therefore requested.
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NRC FORM 316 to 76) NRC%1024J D U.%. GOV CRWENT PRINTING OF FICE: 1979 289-369