ML19170A321

NEIs Presentation Slides for Public Meeting on Endorsement of NEI 96-07, Appendix D, June 25, 2019

ML19170A321
Person / Time
Site:	Nuclear Energy Institute
Issue date:	06/19/2019
From:	Nuclear Energy Institute
To:	Division of Inspection and Regional Support
Govan T, 415-6197, NRR/DIRS
References
NEI 96-07
Download: ML19170A321 (26)

Text

©2019 Nuclear Energy Institute NEI 96-07 Appendix D Criterion 6 Examples June 25, 2019

©2019 Nuclear Energy Institute 2 Sec. 4.3.6 of Appendix D is consistent with NEI 96-07, R1 Two decades of implementation Developed with NOPR and 1999 Final Rule SOC in mind Logic and treatment of Criterion 6 is consistent with the application of other 10 CFR 50.59 Evaluation criteria Consistent with NEI 96-07, R1 Consistent with NRCs Reliability Principle of Good Regulation Supports NRC focus on risk-significant issues Sec. 4.3.6 of Appendix D avoids uneven application of 50.59 Examples Will Show:

©2019 Nuclear Energy Institute 3 Instrument Air Compressor Digital Controls Diesel Generator Jacket Water Surge Tank Level Control Containment Fan Coolers Digital Controls Digital Feedwater Control System As time allows:

Feedwater Debris Strainer Examples for Discussion

©2019 Nuclear Energy Institute 4 The Instrument Air system provides compressed, filtered and regulated air in support of various plant needs.

Compressed air is supplied to the IA system by three 50% capacity (405 scfm), oil-free, reciprocating air compressors, each with its own after-cooler, moisture separator and air receiver.

When Instrument and Station Air Systems are separated, only two of the three IA compressors are required to supply the IA header requirements for both units.

Instrument Air (IA) Compressor Digital Controls

©2019 Nuclear Energy Institute 5 Instrument Air Compressor Digital Controls Example Plant UFSAR

©2019 Nuclear Energy Institute 6 Instrument Air Compressor Digital Controls UFSAR The IA compressors discharge to an IA header which is common to both units.

FMEA: 2 of 3 IA compressors are required during normal ops; low P in the supply line auto starts standby IA compressors Safety analyses: assume loss of the Instrument Air System Proposed Activity Install new IA compressors with digital controls Likelihood of SCCF of all compressors not sufficiently low = 0 of 3 compressors Possible loss of normal feedwater event

©2019 Nuclear Energy Institute 7 IA Compressor Digital Controls Scenario UFSAR Description 3.12 Safety Analyses SA current new different result?/LAR?

Plant 1 - NEI 2/3 0/3 Loss of Normal Feedwater (LONF)

IA system assumed to fail (no change)

No Plant 2 - NEI No existing description LONF No change No Plant 1 - NRC 2/3 0/3 LONF No change Yes Plant 2 - NRC No existing description LONF No change Not Clear

©2019 Nuclear Energy Institute 8 Appendix Ds approach is consistent with NEI 96-07, Rev. 1 using the safety analysis level Appendix Ds approach supports NRC focus on risk-significant issues The NRCs approach appears to require LARs for a lot of very reasonable and benign modifications.

IA Compressor Digital Controls Illustrates

©2019 Nuclear Energy Institute 9 Diesel generator supplies power to required emergency loads D/G needs jacket water supply in order to perform its design function Two 100% redundant trains Surge tank is described as having a manual-operated supply and drain, along with various alarms and a high temperature D/G trip Low level alarm actuates at 200 gallons remaining in a 450 gallon surge tank Drain line averages 5 GPM Effect of operator error on surge tank draining is discussed Diesel Generator (D/G) Jacket Water Surge Tank Level Control

©2019 Nuclear Energy Institute 10 D/G Jacket Water Surge Tank Level Control

©2019 Nuclear Energy Institute 11 D/G Jacket Water Surge Tank Level Control UFSAR One D/G train operates FMEA: low water makeup water replaces losses Safety analyses: assume single failure; one train operates Proposed Activity Replace manual control with digital controllers and air-operated valves Likelihood of SCCF of both controllers not sufficiently low

= 0 of 2 D/G FMEA would examine losing both trains Safety analyses would reflect FMEA outcome

©2019 Nuclear Energy Institute 12 Procedures already exist for:

Local operator monitoring of D/G operation Response to Low Surge Tank alarms

MCR Trouble Alarm typically points to a local panel Operator manipulation of surge tank supply and drain valve 40 minutes (200 gallons being drained at 5 GPM) are available after alarm generation Operator complies with procedural guidance Surge tank function is preserved D/G design function is preserved D/G Jacket Water Surge Tank Level Control - new/revised FMEA

©2019 Nuclear Energy Institute 13 D/G Jacket Water Surge Tank Level Con.

Scenario UFSAR Description 3.12 Safety Analyses SA current new different result?/LAR?

Plant 1 - NEI Detailed FMEA D/G Operation At least one D/G operates (no change)

No Plant 2 - NEI No existing description D/G Operation No change No Plant 1 - NRC Detailed FMEA D/G Operation No change Yes Plant 2 - NRC No existing description D/G Operation No change Not Clear

©2019 Nuclear Energy Institute 14 Appendix Ds approach produces a consistent answer independent of UFSAR detail, avoiding uneven application NRCs approach appears to differ based upon level of UFSAR detail (reinstates problem of uneven application)

NRCs approach is not clear for plants with no existing UFSAR description Appendix Ds approach is consistent with NEI 96-07, Rev. 1 Both developed with NOPR and 1999 Final Rule SOC in mind Revised FMEA = The result of the logically required operator actions in response to the effect of the level controllers failure is the preservation of the D/Gs function D/G Jacket Water Surge Tank Level Control Illustrates

©2019 Nuclear Energy Institute 15 Limits the containment ambient temperature during normal plant operating conditions Reduce containment ambient temperature and pressure following a Loss of Coolant Accident (LOCA) or a Main Steam Line Break (MSLB) inside containment Provides mixing of the sprayed and unsprayed regions of the containment to improve airborne fission product removal Provides a mixed atmosphere for hydrogen control Five containment fan coolers provided Containment Fan Coolers Digital Controls

©2019 Nuclear Energy Institute 16 Containment Fan Coolers Digital Controls

©2019 Nuclear Energy Institute 17 Containment Fan Coolers Digital Controls UFSAR 2 of 5 coolers required to operate following a DBA FMEA: at least two operable coolers has no effect on the Containment Heat Removal System Containment pressure safety analyses: two coolers assumed to operate Proposed Activity Install digital controls for each containment fan cooler Likelihood of SCCF of all fan coolers "not sufficiently low = 0 of 5 coolers following a DBA Calculation that used the cooling rate produced by two fan coolers revised to using a value of zero (0)

©2019 Nuclear Energy Institute 18 Containment Fan Coolers Digital Controls Scenario UFSAR 3.12 Safety Analyses (vi) different result?

(vii) DBLFPB exceeded or altered?

LAR?

Plant 1 -

NEI 2/5 0/5 coolers Ctmt Press.

Yes - SA Acc. Crit.

NOT Met No - SA Acc. Crit.

Met Yes Plant 2 -

NEI No existing description Not Credited No No No Plant 1 -

NRC 2/5 0/5 Coolers Ctmt Press.

Yes No Yes Plant 2 -

NRC No existing description Not Credited Not Clear No Not Clear

©2019 Nuclear Energy Institute 19 Appendix Ds approach produces a consistent answer independent of UFSAR detail, avoiding uneven application NRCs approach appears to differ based upon level of UFSAR detail (reinstates problem of uneven application)

NRCs approach is not clear for plants with no existing UFSAR description Appendix Ds approach focuses on the same safety analysis as criterion 7, but with differing assumptions Criterion 6: to create a possibility, assume SCCF (0/5 coolers)

Criterion 7: to reflect performance as designed, assume single failure (at least 2/5 coolers)

Containment Fan Coolers Digital Controls Illustrates

©2019 Nuclear Energy Institute 20 Main Feedwater Regulating Valves (MFRV) and Bypass Feedwater Regulating Valves (BFRV) automatically control feedwater flow and maintain steam generator water level.

The Steam Generator Water Level Control System (SGWLCS) establishes and maintains the steam generator water level within predetermined limits during normal operating transients. The SGWLCS also maintains the steam generator water level within predetermined limits and unit trip conditions.

Digital Feedwater Control System

©2019 Nuclear Energy Institute 21 Digital Feedwater Control System UFSAR A switchover from the BFRVs to the MFRVs is initiated manually by the operator at approximately 25 percent power UFSAR Section 15.1.2, Feedwater System Malfunctions that Result in an Increase in Feedwater Flow, considers the full opening of one feedwater regulating valve Proposed Activity Install digital controls to use the BFRV alone, the MFRV and BFRV in parallel, or the MFRV alone to automatically control feedwater flow as power level changes.

Possible increase in feedwater flowrate in two loops due to both the MFRVs and BFRVs going fully open.

©2019 Nuclear Energy Institute 22 The reanalysis of the hot full power case feedwater malfunction event in one loop demonstrated that the results and conclusions discussed in UFSAR Section 15.1.2 are acceptable with the proposed change and assuming a SCCF. An analysis of a hot full power case feedwater malfunction event in two loops was also performed and also demonstrated that the results and conclusions discussed in UFSAR Section 15.1.2 for the hot full power case for one loop are also satisfied. Specifically, the peak heat flux does not exceed 118 percent of its nominal value, and the DNBR remains above the design DNBR limit of 1.24/1.23. Additionally the RCS pressure remains below 110%

of RCS design pressure.

Digital Feedwater Control System

©2019 Nuclear Energy Institute 23 Digital Feedwater Control System Scenario UFSAR Description 3.12 Safety Analyses SA current new different result?/LAR?

Plant 1 - NEI 1 con/ loop 1 con/ 2 loops Increase in FW Flow 1 FRV full open 4 FRV full open (2 MFRV & 2 BFRV)

No - SA Acc.

Crit. Met Plant 2 - NEI No existing description Increase in FW Flow See above No - SA Acc.

Crit. Met Plant 1 - NRC 1 con/ loop 1 con/ 2 loops Increase in FW Flow See above Yes Plant 2 - NRC No existing description Increase in FW Flow See above Not Clear

©2019 Nuclear Energy Institute 24 Appendix Ds approach is consistent with NEI 96-07, Rev. 1 using the safety analysis level Appendix Ds approach produces a consistent answer independent of UFSAR detail, avoiding uneven application Consistent with NRCs Reliability Principle of Good Regulation Supports NRC focus on risk-significant issues Digital Feedwater Control System Illustrates

©2019 Nuclear Energy Institute 25 Criterion 6 - Four Major Points 1.

NEI 96-07, Definition 3.9, malfunction of an SSC important to safety is used within Section 4.3.6 of Appendix D consistently 2.

The rulemaking record is clear - the rules intent to identify a different result is to examine the safety analyses 3.

Consistent with NEI 96-07, Rev. 1, Section 4.3.6 of Appendix D avoids uneven application of 10 CFR 50.59 4.

Section 4.3.6 of Appendix D is consistent with the other 10 CFR 50.59 Evaluation criteria

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