ML080380288

Preliminary Request for Additional Information

ML080380288
Person / Time
Site:	Callaway
Issue date:	02/07/2008
From:	Thadani M NRC/NRR/ADRO/DORL/LPLIV
To:	Ameren Corp
Thadani, M C, NRR/DORL/LP4, 415-1476
References
TAC MD7252
Download: ML080380288 (3)

Text

From:

Mohan Thadani To:

Internet:smaglio@ameren.com Date:

2/7/2008 9:53:40 AM

Subject:

PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION-TAC NO. MD7252 Scott:

The NRC staff has reviewed the Ameren UE request regarding one-time AOT extension for EDGs for Callaway plant. The NRC staff has identified a need for additional information. Attached is a preliminary request for additional information. A formal letter request will follow. I request that Ameren respond to the subject request within 30 days, to facilitate timely completion of the requested action.

Thanks.

Mohan REQUEST FOR ADDITIONAL INFORMATION AMERENUE Callaway Plant Docket No. 50-483

1)

Describe the safety margins that are being credited in the license amendment request section titled, Evaluation of Safety Margins. Also, demonstrate that the safety margins for the events analyzed in the Callaway Plant Final Safety Analysis Report will not be impacted during the implementation proposed change.

2)

Based on previously approved diesel generator (DG) Technical Specification (TS) Completion Time (CT) extension requests, the staff has found that certain compensatory measures, in the form of regulatory commitments, need to be implemented during the extended DG CT. These regulatory commitments help ensure continued safe operation of the plant. The following compensatory measures are provided as examples of regulatory commitments that other licensees have provided in support of obtaining DG CT extensions. Provide a discussion as to how you will address each of the following compensatory measures for the Callaway Plant.

No maintenance or testing that affects the reliability of the train associated with the OPERABLE DG will be scheduled during the extended CT. If any testing and maintenance activities must be performed while the extended CT is in effect, an evaluation will be performed in accordance with Title 10 to the Code of Federal Regulations (10 CFR) Section 50.65(a)(4).

An alternate power source with capacity equal to or greater than the capacity of the inoperable DG will be available as a backup to the inoperable DG. After entering the extended CT, this source will be verified available every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and treated as protected equipment.

The scheduling of DG preplanned maintenance will be avoided during seasons when the probability of severe weather or grid stress conditions are high or forecasted to be high.

The system load dispatcher will be contacted once per day to

ensure no significant grid perturbations are expected during the extended CT.

Also, the system load dispatcher should inform the plant operator if conditions change during the extended CT (e.g., unacceptable voltages could result due to a trip of the nuclear unit).

Component testing or maintenance of safety systems and important non-safety equipment including offsite power systems (auxiliary and startup transformers) that increase the likelihood of a plant transient or loss-of-offsite power (LOOP) will be avoided. In addition, no discretionary switchyard maintenance will be allowed.

TS requirements of verification that the required systems, subsystems, trains, components, and devices that depend on the remaining DG(s) are operable and positive measures will be provided to preclude subsequent testing or maintenance activities on these systems, subsystems, trains, components, and devices.

Turbine driven auxiliary feedwater pump will be controlled as protected equipment, and will not be taken out of service for planned maintenance while a DG is out of service for extended maintenance.

3)

In accordance with the defense-in-depth philosophy, describe how the remaining systems will be capable of performing the function of the safety system that is being removed from service.

4)

If the DG on the affected train continues to be functional but not OPERABLE, describe the loading capabilities of the functional DG. Also describe how the functional DG would respond if called upon (e.g., a LOOP event).

Mail Envelope Properties (47AB1B74.3C3 : 23 : 35106)

Subject:

PRELIMINARY REQUEST FOR ADDITIONAL INFORMATION-TAC NO. MD7252 Creation Date 2/7/2008 9:53:40 AM From:

Mohan Thadani Created By:

MCT@nrc.gov Recipients ameren.com smaglio (Internet:smaglio@ameren.com)

Post Office Route ameren.com Internet Files Size Date & Time MESSAGE 881 2/7/2008 9:53:40 AM RAI_ML0803601840.doc 33280 2/7/2008 9:51:08 AM

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