ML20039E545

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Forwards Addl Info Clarifying Certain Design Features Incorporated as Part of Equipment Used for Automatic Switchover of Suctions for HPCI & RCIC Sys,Per NRC Request
ML20039E545
Person / Time
Site: Fermi DTE Energy icon.png
Issue date: 01/06/1982
From: Tauber H
DETROIT EDISON CO.
To: Youngblood B
Office of Nuclear Reactor Regulation
References
EF2-55-977, NUDOCS 8201110015
Download: ML20039E545 (3)


Text

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f 'OJanuary 6, 1982 42 > EF2 - 55,977

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l Mr. B. J. Youngblood, Chief U. S. Nuclear Regulatory Commission i

Office of Nuclear Reactor Regulation Division of Licensing l Washington, D. C. 20555

Dear Mr. Youngblood:

Reference:

Enrico Fermi Atomic Power Plant, Unit 2 NRC Docket No. 50-341 i

Subject:

Automatic Switchover of the Suetions for j the HPCI and RCIC Systems Detroit Edison has carefully reviewed your recent request for clarification of certain design features incorporated as part of the equipment used for automa-l tic switchover of the suctions for the HPCI and RCIC systems. Attached please find a description of the system which meets the guidance of the ICSB position on freeze protection. Secondly, a discussion and justification of the seismic design adequacy of the level instrumentation is included. Finally, a state-l ment of the quality design basis for the system is provided. Detroit Edison believes this supplemental material addresses the identified technical concerns.

l If further clarification is required, please contact Mr. L. E. Schuerman, 313-649-7562.

Sincerely, f 'Bool 4

f,(.AAf $t' 'K j til Enclosure cc: Mr. L. L. Kintner 8201110015 820106 PDR ADOCK 05000341 Mr. B. Little A PDR

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Attachment to EF2-55,977 AUTOMATIC HPCI/RCIC SUCTION SWITCHOVER SYSTEM As discussed in the Fermi 2 Final' Safety Analysis Report on page H.II.K.3 22-1, a redundant pair of analog level transmitters (E41-N061B & D) provide an automatic transfer of the RCIC and HPCI suction valves-(n low condensate storage tank level. The condensate storage tank level instrumentation is designed to meet the ICSB position with respect to freeze protection as described in the following summary:

A single source connection penetrates the tank. This source connection is common to both the analog transmitters which monitor tank level for the purpose of transferring the RCIC/HPCI pump suction and the

-transmitter associated with the continuous wide range tank level indication provided in the main control room. This equipment is contained within a large insulated steel cabinet (H21-P492) welded directly to the exterior of the condensate storage tank about three feet above ground level. The access doors to' the cabinet are locked, and administratively controlled by the plant operating staff. The environ-ment within the cabinet is maintained at a temperature of approximately 80 degrees Fahrenheit by a 100 watt radiant strip heater and a local control thermostat.

A temperature sensing device which is independent of the strip heater and its associated control thermostat is_also located within the cabinet. This sensor pro-duces a visual and audible alarm in the main control room whenever the temperature in the transmitter cabi-net falls below thirty five degrees Fahrenheit. The cabinet temperature control and the low temperature alarm are electrically independent and powered from completely independent and diverse power sources. A failure of either would not affect the ability of the other to perform its function. In order to guarantee the continued performance of the environmental control-and monitoring systems, Edison will perform a yearly functional surveillance of the systems prior to the advent of freezing weather.

Edison has justified the non-seismic location of the transmitters used in the suction transfer system based primarily on the degree of conservatism in instrumentation seismic design. The level transmitters used in this transfer application were seismically qua.ified as described in the licensing topical report NED0-21617

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Attachment to.EF2-55,977 i Page 2 l

L Fermi site ground response spectra applicable to a

transmitter mounting on the tank located at grade level would fall well below the values used for qualification of the transmitters in the reference document. As a result, the transmitters;are expected to operate pro-perly during and after a seismic event. As an added l degree of conservatism, a complete failure of the-tank l and/or transmitter system would result in an automatic suction transfer since the loss of the current signal from either transmitter will cause the trip units (E41-N661B and D) and associated trip relays to transfer the RCIC and HPCI suction valves to the suppression pool. These trip units and relays are located on the first floor of the' reactor building (reference C-9) in panel H21-P081. These devices and cabinet are located within the-seismically qualified portion of the plant and meet the environmental and seismic qualification requirements for Class 1E electrical equipment.

All of the equipment which accomplishes the automatic suction valve transfer on low condensate tank level is classified as quality level 1. The transmitters were purchased as qualified instruments along with the balance of the transfer system and are included with the trip units and relays in the plant technical speci-fications since the surveillance requirement includes the entire measurement loop.

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