ML12166A560

Licensee Presentation on June 12 & 13, 2012, Meeting License Amendment Request on NFPA 805 Adoption

ML12166A560
Person / Time
Site:	Arkansas Nuclear
Issue date:	06/12/2012
From:	Clark R Entergy Operations
To:	Kalyanam N Plant Licensing Branch IV
Kalyanam N
Shared Package
ML12166A553	List: ML12166A560 ML12167A021
References
TAC ME8282
Download: ML12166A560 (28)

Text

License Amendment Request NFPA 805 Acceptance Review Arkansas Nuclear One Unit 2 June 12, 2012

NRC four areas of concern with the LAR

• The modifications for transition need to be described and, as appropriate, modeled in the PRA to properly estimate the change in risk associated with transition. The LAR needs to be supplemented with the descriptions of these modifications and provide adequate information to review the evaluations supporting these modifications.

• About one third of the fire areas in the "Additional Risk of RAs column of Table W-2 of the LAR do not contain a quantitative risk result. The LAR needs to be supplemented with all of the quantitative Recovery Action risk estimates to demonstrate that the evaluations supporting the transition have been satisfactorily completed.

• Attachment G of the LAR states that ANO-2 ANO 2 has no primary control station, besides the Main Control Room (MCR), yet only eight Recovery Actions are identified for Fire Area G. It is also unclear how both the total change in risk and the additional risk from Recovery Actions is bounded by a risk estimate of "0.0." The LAR needs to be supplemented with additional discussion about the planned modifications and Recovery Actions, and how these are modeled in the PRA in sufficient detail to explain the unexpected results.

• Two sensitivity studies compare the results based on one "unaccepted method" to results based on another "unaccepted method." The LAR needs to be supplemented with the risk results (in relation to the sensitivity analyses for non-suppression probability for long-term fires and adjustment factor for electrical cabinet ignition frequency) calculated using an acceptable analysis method.

Technical Acceptance Issues

1. ANO has prepared more detailed modification descriptions. Draft changes available for discussion.

2. ANO has prepared a draft analysis to address the risk estimates of the quantitative Recovery Actions (RA).

These draft RA risk values are available for discussion.

3. ANO will explain the results in Fire Area G (Control Room) and how the mods and RAs were modeled in the Fire PRA.

4. ANO has drafted a new Sensitivity analysis in compliance with NUREG/CR-6850 for comparison to the current results. Further analysis is needed to accurately reflect the risk and minimize the need for unnecessary plant modifications.

Item No. 1 -

Modification Details The modifications for transition need to be described and, as appropriate, modeled in the PRA to properly estimate the change in risk associated with transition. The LAR needs to be supplemented with the descriptions of these modifications and provide adequate information to review the evaluations supporting these modifications.

Item No. 1 -

Modification Details

• Detailed final plant configurations have been completed and will be discussed for all 16 modifications identified

• The Th modifications difi ti will ill b be completed l t d iin a manner that supports the assumptions of the Fire PRA

Insert Att. S Excerpt Item No. 2 - Risk Estimates for Recovery Actions About one third of the fire areas in the "Additional Risk of RAs column of Table W-2 of the LAR do not contain a quantitative risk result. The LAR needs t be to b supplemented l t d with ith allll off th the quantitative Recovery Action risk estimates to demonstrate that the evaluations supporting the transition have been satisfactorily completed.

Item No. 2 - Risk Estimates for Recovery Actions

• The delta risk from recoveries are currently being drafted and preliminary results are available for review

• An A example l off th the iinformation f ti tto b be provided id d iin the Supplement to the ANO-2 LAR is contained in the next slide

Example of the information to be provided in the Supplement to address the delta risk of recoveries Table W-2 ANO-2 Fire Area Risk Summary Additional Risk Fire NFPA 805 Fire Area Fire Area VFDR Recovery Fire Risk Eval Fire Risk Eval Area Description of RAs Area Basis CDF LERF (Yes/No) Actions CDF LERF (CDF/LERF) fire zones 2019-JJ, 2032-JJ, 2040-JJ, and 2068-DD (boric Revised Column for delta acid condensate tank room, DD spent resin storage tank 4.2.4.2 2.45E-06 2.76E-08 yes no -2.85E-06 -9.64E-08 n/a room, corridor, and hot machine shop)

EE-L fire zones 2055-JJ and 2084-DD (piping penetration rooms) risk of Recovery action only 4.2.4.2 3.81E-07 7.53E-09 yes yes -7.89E-07 -2.64E-08

-6.00E-09/1.51E-09 fire zone 2111-T (lower south EE-U electrical penetration room) 4.2.4.2 2.03E-06 4.81E-08 yes yes -5.77E-06 -1.94E-07 2.00E-08/2.70E-09 fire zone 2025-JJ (motor-FF driven emergency feedwater 4232 4.2.3.2 1 15E 08 1.15E-08 3 66E 10 3.66E-10 no n/a n/a n/a n/a pump room) fire zones 2199-G, 2119-H, 2136-I, 2137-I, 2150-C, G 2098-C, and 2098-L (control 4.2.4.2 2.64E-06 3.52-08 yes yes -2.65E-06 -9.78E-08 -2.00E-08/1.60E-09 room and other alternate shutdown areas) fire zones 2074-HH and 2081-HH (electrical GG equipment room and upper 4.2.4.2 1.03E-06 2.17E-08 yes yes -1.12E-05 -3.82E-07 -9.27E-06/3.20E-09 north and lower north piping penetration room).

fires zones 2063-DD, 2072-R, 2073-DD, 2096-M, 2106-R, and 2107-N (sample HH room, VCT room, 2B-62 4.2.4.2 3.11E-06 4.65E-08 yes yes -5.80E-07 -2.18E-08 -1.13E-06/1.23E-08 room, 2B-63 room, degasifier vacuum pump room, and corridor) fire zone 2101-AA (north II switchgear 2A-3 room) 4.2.4.2 2.90E-06 9.31E-08 yes yes -1.33E-04 -4.52E-06 -2.70E-07/6.80E-09 JJ fire zone 2109-U (corridor) 4.2.4.2 2.70E-06 7.97E-08 yes yes -3.78E-06 -1.21E-07 -1.50E-07/1.24E-08 fire zones 16-Y and 2020-JJ (clean waste receiver tank K 4.2.3.2 6.47E-10 1.44E-11 no n/a n/a n/a n/a room and boron holdup tank vault)

Example of the information to be provided in the Supplement to address the delta risk of recoveries Table W-2 ANO-2 Fire Area Risk Summary Fire Area Zero delta risk removed and Area Description NFPA 805 Basis Fire Area CDF Fire Area LERF VFDR (Yes/No)

Recovery Actions Fire Risk Eval CDF Fire Risk Eval LERF Additional Risk of RAs (CDF/LERF)

DD actual delta risk fire zones 2019-JJ, 2032-JJ, 2040-JJ, and 2068-DD (boric acid condensate tank room, 4.2.4.2 2.45E-06 2.76E-08 yes no -2.85E-06 -9.64E-08 n/a spent resin storage tank incorporated to show room, corridor, and hot machine shop) fire zones 2055-JJ and 2084-negative delta risk

-6.00E-09/1.51E-09 EE-L DD (piping penetration 4.2.4.2 3.81E-07 7.53E-09 yes yes -7.89E-07 -2.64E-08 rooms) fire zone 2111-T (lower south EE-U electrical penetration room) 4.2.4.2 2.03E-06 4.81E-08 yes yes -5.77E-06 -1.94E-07 2.00E-08/2.70E-09 fire zone 2025-JJ (motor-FF driven emergency feedwater 4232 4.2.3.2 1 15E 08 1.15E-08 3 66E 10 3.66E-10 no n/a n/a n/a n/a pump room) fire zones 2199-G, 2119-H, 2136-I, 2137-I, 2150-C, G 2098-C, and 2098-L (control 4.2.4.2 2.64E-06 3.52-08 yes yes -2.65E-06 -9.78E-08 -2.00E-08/1.60E-09 room and other alternate shutdown areas) fire zones 2074-HH and 2081-HH (electrical GG equipment room and upper 4.2.4.2 1.03E-06 2.17E-08 yes yes -1.12E-05 -3.82E-07 -9.27E-06/3.20E-09 north and lower north piping penetration room).

fires zones 2063-DD, 2072-R, 2073-DD, 2096-M, 2106-R, and 2107-N (sample HH room, VCT room, 2B-62 4.2.4.2 3.11E-06 4.65E-08 yes yes -5.80E-07 -2.18E-08 -1.13E-06/1.23E-08 room, 2B-63 room, degasifier vacuum pump room, and corridor) fire zone 2101-AA (north II switchgear 2A-3 room) 4.2.4.2 2.90E-06 9.31E-08 yes yes -1.33E-04 -4.52E-06 -2.70E-07/6.80E-09 JJ fire zone 2109-U (corridor) 4.2.4.2 2.70E-06 7.97E-08 yes yes -3.78E-06 -1.21E-07 -1.50E-07/1.24E-08 fire zones 16-Y and 2020-JJ (clean waste receiver tank K 4.2.3.2 6.47E-10 1.44E-11 no n/a n/a n/a n/a room and boron holdup tank vault)

Item No. 3 - Recovery Actions Credited for Control Room Abandonment Attachment G of the LAR states that ANO-2 has no primary control station, besides the Main Control Room (MCR), yet only eight Recovery Actions are identified for Fire Area G. It is also unclear how both the total changeg in risk and the additional risk from Recovery Actions is bounded by a risk estimate of "0.0." The LAR needs to be supplemented with additional discussion about the planned modifications and Recovery Actions, and how these are modeled in the PRA in sufficient detail to explain the unexpected results.

Item No. 3 - Recovery Actions Credited for Control Room Abandonment

• Fire Area G contains several zones including the Control Room

• A fire in Fire Area G may result in control room abandonment

• Mods and operator actions outside the Control Room have been credited for Core Damage Mitigation

Proposed Control Room Modifications for Transition to NFPA-805

• Modification to eliminate potential spurious operation

- 2CV-1002 ADV Block valve

- 2CV-1052 2CV 1052 ADV Bl Block k valve l

- 2CV-4698-1 ECCS Vent Valve

• AFW Modification

Human Recovery Actions Credited for Control Room Abandonment Scenario

• Operator action to Isolate blowdown

• Operator action to Isolate Letdown Flow

• Operator action to trip RCPs at the switchgear

• Operator action to start and align AFW

• Operator action to stop Charging Pumps

• A specific location is used by the Shift Manager to monitor process instrumentation and coordinate operations activities

Control Room Analysis Discussion

• RCS integrity and primary to secondary heat removal are evaluated crediting the proposed mods and recoveries

• Additional Defense in Depth p actions will enhance plant control and reduce the likelihood of equipment damage

• CDF = ~2.6E-06 (Crediting mods and recovery actions)

Control Room Analysis Discussion (Contd)

• Spurious Operation of equipment has been considered in the Fire PRA analysis.

Pump start with no suction HPSI - mini-recirc capability LPSI - spurious pump start EDG and support systems assumed failed

Control Room Analysis Discussion (Contd)

Compliant Case Analysis Methodology

• Control Room Variance from Deterministic Requirements (VFDR)

Compliant Case Analysis Methodology

• Single success train for plant control and mitigation

• RG 1.205: The deterministically compliant plant has been referred to as an ideal plant l t th thatt may nott exist i t or be b feasible f ibl iin practice.

• Modeling configuration assumed

- EFW Train A to SG B

- RCS remains intact

Delta Risk Analysis IGF CDF LERF Scenario Zone Description (/rx-yr) NSP SF CCDP (/rx-yr) CLERP (/rx-yr) 2199-G Compliant Case 3.79E-05 1.0 1.0 1.40E-01 5.29E-06 3.50E-03 1.33E-07 Post Transition 2199-G Case 3.79E-05 1.0 1.0 6.97E-02 2.64E-06 9.29E-04 3.52E-08 Results Delta Delta CDF -2.65E-06 LERF -9.78E-08

Item No. 4 - Sensitivity Study Two sensitivity studies compare the results based on one "unaccepted method" to results based on another "unaccepted method." The LAR needs to be supplemented with the risk results (in relation to the sensitivity analyses for non-suppression probability for long-term fires and adjustment factor for electrical cabinet ignition frequency) calculated using an acceptable analysis method.

Item No. 4 - Sensitivity Study

• Electrical Panel Propagation Factors are removed from the original analysis to comply with 6850 methodology.

- CDF Analysis

- Multi-compartment/Hot Gas Layer (MCA/HGL) screening

• This will meet the NRC expectation for 6850 compliance

Core Damage Frequency

• Draft results show an increase in risk from that reported in Attachment W of the LAR

- CDF increased from 4.3E-05/yr to

~6 6.0E 0E-05/yr 05/yr

- LERF increased from 8.3E-07/yr to

~1.3E-06/yr

• Results will be provided in the LAR Supplement

Multi-compartment/Hot Gas Layer

• Draft results show that less than 2% of 1955 previously screened scenarios will no longer screen

• The list of unscreened fire scenarios will be provided in the LAR Supplement

Additional Level of Effort

• Efforts have begun to perform fire modeling.

• This effort is expected to more accuratelyy calculate the risk of a MCA/HGL as well as reduce the increase in CDF

• The refined results will be provided once this additional level of effort is completed

Example Case

• Scenario (2098-C) was chosen to analyze the impact of additional walkdowns and fire modeling

• 2098-C is the Core Protection Calculator Room

- This room uses Halon for fire suppression

- Low voltage electrical panels are contained within this room

- Current analysis assumes full room burnup

• The new fire modeling shows that a fire in this room will not generate a hot gas layer.

• This new information will be used to refine the risk results for fires in this zone

Impact on ANO-1 LAR

• Additional work to supplement the ANO-2 LAR challenges completion of the ANO-1 LAR

• ANO-1 ANO 1 has similar issues identified for ANO-2

• The ANO-1 LAR submittal is scheduled for August 31, 2012

Summary ANO-2 supplemental response will be provided by the July 11 deadline

Questions ??