ML12278A255

Licensee Slide Presentation, ANO-2 NFPA 805 Application, at the October 9, 2012, pre-submittal Meeting to Discuss the NFPA 805 Application

ML12278A255
Person / Time
Site:	Arkansas Nuclear
Issue date:	10/09/2012
From:	Kalyanam N Plant Licensing Branch IV
To:	Entergy Operations
Kalyanam N
Shared Package
ML12278A251	List: ML12278A253 ML12278A255
References
TAC ME9706
Download: ML12278A255 (10)

Text

ANO-2 NFPA 805 Application NRC Public Meeting - October 9, 2012 In advance of ANO-2 re-submittal of its NFPA 805 application, Entergy requested a public meeting with the NRC in order to ensure gaps which resulted in non-acceptance of the previous ANO-2 License Amendment Request (LAR) will be resolved appropriately.

Agenda

1. Description of non-acceptance and gaps as described in NRC letter, followed by a description of Entergys proposed resolution

2. Open discussion to ensure Entergys understanding of gaps (following each gap identified)

ANO-2 NFPA 805 Application

• On September 7, 2012, the NRC notified Entergy of non-acceptance of ANO-2 Application to Transition to NFPA 805, including the loss of enforcement discretion of fire protection issues, based on the following:

1) the LAR contained insufficient information supporting a new method estimating the change in risk associated with transition (transition risk),

2) regulatory guidance was not followed because sensitivity studies were not provided on the new method to estimate the transition risk and not completed on the other new method related to the values assigned to non-suppression probabilities, and

3) the results of replacing the new methods with acceptable methods could precipitate further changes in the plant or the fire probabilistic risk analysis (PRA).

ANO-2 NFPA 805 Application ITEM 1

1) the LAR contained insufficient information supporting a new method estimating the change in risk associated with transition (transition risk)

The NRC letter also stated:

The expectation for performing the fire risk evaluation is to identify conditions that deviate from the deterministic requirements (designated as Variances from the Deterministic Requirements or VFDRs); present those VFDRs on a fire-area basis in the Fire Risk Evaluation and in the LAR; and indicate how each VFDR has been addressed either through plant modifications or an estimate of the risk increase associated with accepting the VFDR as part of the post-transition licensing basis. For the alternative shutdown area at ANO-2, Fire Area G (Area G), the LAR did not provide this information.

ANO-2 NFPA 805 Application ITEM 1 (continued)

The NRC letter also stated:

the LAR supplement explains that the baseline risk is estimated by assuming a minimally compliant success path defined as one emergency feed water train to one steam generator and an intact primary coolant system. This approach overestimates the baseline risk because it does not credit the in-situ equipment and procedures that would be available after the current configuration has been brought into compliance by removal of the VFDRs. The supplement further clarifies that the post transition risk only assumes that fire affected equipment fails and is, therefore, a realistic estimate of the post transition risk. Subtracting an overestimated baseline risk from a realistic post-transition risk yields a transition risk that is smaller than warranted and may incorrectly result in a negative transition risk.

ANO-2 NFPA 805 Application ITEM 1 (continued)

ANO Response ANO-2 Control Room (Area G) Analysis Methodology

• VFDRs for the Control Room have been identified using Deterministic Criteria

• The VFDRs address the following Safety Functions:

• Reactor Coolant System Pressure Control

• Inventory

• Decay Heat Removal

• Vital Auxiliaries - Electrical

• Vital Auxiliaries - Service Water

• Vital Auxiliaries - Heating, Ventilation, and Air Conditioning

ANO-2 NFPA 805 Application ITEM 1 (continued)

ANO Response (continued)

ANO-2 Control Room (Area G) Analysis Methodology (continued)

• The compliant case has been constructed by incorporating the VFDRs as if the VFDRs were brought into compliance with the deterministic regulation

• As-Built/As-Operated Fire PRA model is used in this application

• The results of the new compliant case is ~1.2E-01 CCDP

• This compares closely to the previous results of 1.4E-01 CCDP

• The delta CDF result is negative based on the Auxiliary Feedwater (AFW) pump modification which provides risk benefit over existing Emergency Feedwater pumps

ANO-2 NFPA 805 Application ITEM 1 (continued)

OPEN DISCUSSION

ANO-2 NFPA 805 Application ITEM 2

2) regulatory guidance was not followed because sensitivity studies were not provided on the new method to estimate the transition risk and not completed on the other new method related to the values assigned to non-suppression probabilities The NRC letter also stated:

Additionally, the LAR used non-suppression probabilities different from those that the NRC has accepted. The supplement did not provide the results of the sensitivity study using accepted non-suppression probabilities instead of values proposed in the LAR. Instead, you provided a commitment to submit the results of scenario evaluations and the results of a focused scope peer review of fire modeling by November 2, 2012.

ANO-2 NFPA 805 Application ITEM 2 (continued)

ANO Response Sensitivity Analysis for NSPs

• Completion of sensitivity evaluation based on approved methods of the unscreened scenarios is ongoing

• New NSP probabilities are being reviewed for incorporation into the multi-compartment analysis (MCA)

OPEN DISCUSSION

ANO-2 NFPA 805 Application ITEM 3

3) the results of replacing the new methods with acceptable methods could precipitate further changes in the plant or the fire probabilistic risk analysis (PRA).

ANO Response

• Thus far, the development of the VFDRs and the corresponding revision to the Control Room analysis has not identified any additional plant modifications or model changes beyond those previously identified.

• The incorporation of acceptable methods into the sensitivity analysis is ongoing. Finalization of this effort will dictate whether additional changes to plant or the fire PRA are required.

OPEN DISCUSSION