ML18064A638
| ML18064A638 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 03/02/1995 |
| From: | Haas K CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| RTR-REGGD-01.097, RTR-REGGD-1.097 NUDOCS 9503070392 | |
| Download: ML18064A638 (3) | |
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1, consumers Power POWElllNG MICHIGAN'S fl1UJGRES5 Palisades Nuclear Plant: 27780 Blue Star Memorial Highway, Covert, Ml 49043 March 2, 1995 Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, DC 20555 KurtM. Haas Plant Safety and Licensing Director DOCKET 50-255 - LICENSE DPR PALISADES PLANT - PALISADES PLANT REQUEST FOR DEVIATION FROM REGULATORY GUIDE 1.97 REQUIREMENTS -
ADDITIONAL INFORMATION By letter dated October 20, 1987, the NRC provided the Staff's Safety Evaluation Report (SER) on Palisades Response to Generic Letter 82-33, "Conformance to Regulatory Guide (RG) 1.97.
11 The SER stated that Palisades conforms with, or had acceptably justified deviations from, the guidance of RG 1.97 for each*post accident variable, with minor exceptions.
For the Condensate Storage Tank (CST) water level, the SER referred to our commitment to upgrade the power supply with seismically qualified components.
This upgrade was subsequently completed and it was our belief that the condensate storage tank water level indication was in full compliance with RG 1.97 requirements.
Recent review of cable separation issues at Palisades identified that the cables for both channels of CST level instruments are routed through the non-Seismic Category I turbine building. This cable routing is not in strict compliance with the require~ents of RG 1.97.
Our letter dated October 31, 1994 requested a deviation from the RG 1.97 requirements related to seismic qualification of the CST water level instrumentation and provided information supporting that request.
As a result of Staff reviews and discussion during our January 24, 1995 conference call, it was agreed that additional information supporting the deviation request would be provided.
For clarity, this letter contains all information supporting our request for deviation from the RG 1.97 requirement that the condensate storage tank level instrumentation be seismically qualified, and replaces our October 31, 1994 submittal.
9503070392 ~§8~8~55 PDR ADOCK PDR
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JUSTIFICATION FOR DEVIATION FROM THE REGULATORY GUIDE 1.97 REQUIREMENTS FOR REDUNDANT.SEISMICALLY QUALIFIED CONDENSATE STORAGE TANK LEVEL INSTRUMENTATION For post accident operation, the Condensate Storage Tank (CST) provides a 1
- source of water to the auxiliary feedwater pumps for decay heat removal via the steam generators.
Level indication for the 125,000 gallon CST tank is provided in the control room by redundant level indicators driven by two separate level transmitters mount~d adjacent to the tank~ These redundant level instrumentation channels meet all Regulatory Guide 1.97 Category 1 requirements, with the exception that cables for both channels are routed through the non-Seismic Category I turbine buildi.ng. Cabling for one of the level instrument channels has not been reviewed and no attempt has been made to specifically identify the routing or judge seismic capability for this channel. Cabling for the second channel of level instrumentation has been routed to preclude damage due to seismic events.
Our request for deviation is based on our judgement that seismic qualification for the cabling for both channels of the condensate storage tank level instruments is not needed.
We have verified the seismic ruggedness of one channel and during an event, time is available and procedures are in place to adequately mitigate the unlikely s~enario of losing both channels of Condensate Storage Tank (CST) level instrumentation.
The basis for this justification follows:
- 1.
The tables for each set of the redundant CST level indicating channels take different routes through the turbine building. Drawings show that one channel is routed in standard cable trays while the other has been walked down and verified to be routed in its own conduit.
- 2.
The channel _that is run in conduit has b~en selectively routed through the turbine building to preclude damage due to seismic events.
The Palisades turbine building has previously been evaluated and remains intact (no collapse) following a safe shutdown earthquake ( FSAR Section 5.7.3.1.2). The conduit is either routed away from block walls or protected from block wall collapse. Over much of its length, the conduit is protected by building steel by mounting the condu H on the web of heavy I-beams.
Routing of this cable was walked down by the plant seismic capability engineers who are qualified under the SQUG program and experienced in the design of seismic structures and supports.
The review.
concluded that the conduit was seismically adequate and well protected from adverse seismic interactions such that it is highly unlikely that a design basis seismic event would disable this channel of CST level instrumentation cabling in the turbine building.
- 3.
In the unlikely event that both channels of indication were lost, procedures are in place to direct the operators to assure a successful feedwater path..
With the CST unavailable, or its inventory jeopardized, plant Emergency Operating Procedures (EOP) provide instruction for assuring alternate sources of feedwater, such as from the condensate pumps, or service water or firewater systems. (Several EOP's refer to the
2 condensat~ storage tank level. For example, Success Path flR-1 step 13 of EOP-9 directs the operator to evaluate feedwater inventory using Attachment E-1.
Attachment E-1 gives alternative sources of water to fulfill the feedwater requirements.
In addition, Success Path HR-2 step 20 of EOP-9 gives direction that feedwater can be supplied from the service water system or the fire water system if the condensate storage tank is not available}.
Also, there is ample time for the plant to respond to a loss of tank level indication.
As an example, based on the minimum water level required in the CST, in response to a Station Blackout (SBO} the plant would have over four hours available to take actions to ensure an
. adequate supply of condensate storage tank inventory.
(Station Blackout compliance provides a method for determining how much water would be needed to remove decay heat during an SBO event. Calculations applicable to Palisades (EA-SB0-1} show that 55,964 gallons of water are required to remove decay heat for four hours.
FSAR section 9.7.2.1 states that the low-level alarm for T-2 is set at 88,300 gallons to assure that the required inventory is maintained}.
In summary, granting relief from the R.G.1.97 requirements for the condensate
- storage tank level instrument cabling to be Seismic Class I will not impair the plant's ability to meet the feedwater design basis requirements.
It is our judgement that one channel of the level instrumentation will survive a design basis seismic event.
In the unlikely event that both channels of condensate storage tank level instrumentation are lost, we have time and procedures are in place to assure that the source of water for decay heat removal is maintained.
SUMMARY
OF COMMITMENTS This letter contains no new commitments.
t Kurt M Haas Plant Safety and Licensing Director CC Administrator, Region III, USNRC Project Manager, NRR, USNRC NRC Resident Inspector - Palisades