ML19255K397
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TMI-I Restart SER Supolement Inout 2.1.7.a Automatic Initiation cf the Auxiliary Feedwater System for PWR's The Clarifications for this item were taken from a preliminary draft of the Discussion of TMI Lessons Learned Short Term Requirements. The final Clarn ications for item 2.1.7.a should read as follows:
CLARIFICATION Control Grade (Short-Term) 1.
Provide automatic / manual initial of AFWS.
2.
Testability of the initiating signals and circuits is required.
3.
Initiating signals and circuits shall be powered from the emergenty buses.
4.
'!ecessary pumps and valves shall be included in the automatic sequence of the loads to the emergency buses. Verify that the addition of these loads does not compromise the emergency diesel generating capacity.
5.
Failure in the automatic circuits shall not result in the loss of manual capability to initiate the AFWs from the control room.
6.
Other Considerations a.
For those designs where instrument air is needed for operation, the electric power supply requirement should be capable of being manually connected to emergency power sources.
In the Status Report we required additional justification for not meeting safety grade requirements for the main feedwater pump differential pressure switches and circuitry which will be utilized in the long term safety grade design for automatic initiation of emergency feedwater on loss of both 8004100
main feedwater pumps.
In Amendment 12, the licensee indicated that the model of differential pressure switch to be used has been seismically 0
tested and will function in a temperature range of -60 to 200 F.
The switches will be arranged to meet the single failure criterion, two switches per main feedwater pump (one per train). However, they cannot be treated as fully safety grade as they are installed in a non-seismic building. Their circuits will therefore be tied to the respective EFW initiating circuits through buffer relays. We have requested and the licensee has agreed to provide qualification documentation for the buffer relays., Based on the above, we conclude that the licensee has satisfactorily resolved our concern in this area and the proposed design is acceptable.
The present EFW system design requires instrument air for operation of the EFW flow control valves and steam admission valves to the EFW pump turbine.
The new backup air ccmpressor which provides air to these valves in the event of loss of normal instrument air is powered frcm an emergency power supply and is automatically loaded to its associated diesel generator in the event of aloss of offsite power. The backup air compressor is then manually started by the operator. The backup air system also contains a passive air reservoir for additional assurance of air supply. Refere to Order Item la., No. 2 for further discussion of this feature. We, therefore, conclude that the licensee meets the requirement identified in Clarification 6a.