ML21222A034

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SNC Slides - Hatch TSTF-505 LAR - Pre-Submittal Meeting - 08-16-2021
ML21222A034
Person / Time
Site: Hatch  Southern Nuclear icon.png
Issue date: 08/16/2021
From:
Southern Nuclear Operating Co
To:
Office of Nuclear Reactor Regulation
Lamb J
References
EPID L-2021-LRM-0072
Download: ML21222A034 (18)
v • d • e


Text

Hatch Pre-Submittal Meeting for TSTF-505 Revision 2 August 16, 2021

Meeting Agenda

  • Introductions
  • PRA Models and Configuration Risk Model Overview
  • License Amendment Request Overview 2

PRA Models and Configuration Risk Model Overview

Overview of PRA Portion of HNP TSTF-505 LAR

  • PRA Acceptability
  • PRA models are periodically updated to reflect plant changes and updated data
  • Uncertainty analysis performed per NUREG-1855 Rev 1.
  • PRA models are peer-reviewed and F&O Closure was independently validated
  • Seismic: Penalty applied for CDF and LERF (detailed in Enclosure 4 to LAR)
  • Other External Hazards screened per the standard
  • High Winds: losses of offsite power (LOOPs) included in internal event (IE) PRA (Other High Wind effects screened)
  • Unit-specific PRAs will be used for application
  • Sample RICT calculations to be presented in LAR are for Unit 2 configurations.
  • A sample of Unit 1 configurations will also have RICTs calculated, to demonstrate the similarity between unit results.

4

Internal Events / Internal Flood PRA November 2009 - HNP IE and internal flooding (IF) PRA model was subject to a full-scope peer review against RG 1.200 Rev. 2 utilizing guidance in NEI-05-04.

IE and IF open findings were reviewed; all but 2 IE and 2 IF closed in April 2017 for the IE and IF PRA models using the process documented in Appendix X to NEI 05-04, NEI 07-12, and NEI 12-13, Close-out of Facts and Observations (F&Os) as accepted by NRC (ML17079A427).

Two IF findings required a focused scope peer review, performed in October 2019 and findings closed.

There are two remaining open IE findings related to documentation. Corrective actions for those have been performed and all applicable supporting requirements are met at capability category II.

IE and IF peer review and finding closures examined by NRC during 50.69 submittal review (see document ML20077J704).

5

Fire PRA May 2016 - HNP Fire PRA was subject to full-scope peer review against RG 1.200 Rev. 2 utilizing guidance in NEI 07-12.

Findings were reviewed and closed in October 2017 for the Fire PRA models using the process documented in Appendix X to NEI 05-04, NEI 07-12, and NEI 12-13.

There are no open findings, and all applicable supporting requirements are met to at least capability category II.

SNC will use as-built Fire PRA, and will only credit implemented NFPA-805 modifications.

Fire PRA peer review and finding closeout reviewed during HNP NFPA-805 submittal review (see document ML20066F592).

6

RICT Program Configuration Risk Model RICT will use Configuration Risk Model as currently used for existing Maintenance Rule a(4) Configuration Risk Management Program (CRMP)

Uses PHOENIX Risk Analysis Software. Operations and Work management familiar with software, and it is integrated with clearance and work scheduling software.

Incorporates RICT calculation features. PHOENIX used for example RICT calculations in submittal.

Utilizes single fault tree, all hazard model, re-quantified for each configuration.

One-Top model has been validated to produce identical results to individual hazards. One-top model is used for all HNP risk-informed applications.

7

License Amendment Request LAR Discussion

  • RICTs apply in Mode 1 only, consistent with PRA model
  • Only PRA modeled features (or appropriate surrogate) have RICT proposed
  • No Loss of Function RICTs proposed
  • Additional administrative (clean-up) items included in LAR
  • Variations and administrative items discussed on upcoming slides 9

Administrative Changes

  • Remove one-time, temporary changes to Unit 2 TS 3.5.1, ECCS - Operating and Unit 1 and Unit 2 TS 3.8.1, AC Sources - Operating
  • These were one-time allowances to extend the CTs, and are no longer applicable
  • Remove page 3.4-25 from both Unit 1 and Unit 2 TS
  • Page is a duplicate of page 3.4-22 reflecting LCO 3.4.10
  • Revise title of LCO 3.3.2.2 Feedwater and Main Turbine Trip High Water Level Instrumentation, by moving Trip to after Level. Also add high water level to LCO statement
  • This phrasing will establish consistency with phrasing in the Actions, Surveillance Note, and Bases
  • Change is also consistent with NUREG-1433 phrasing 10

Variations

  • Industry precedence (Peach Bottom) exists for including a RICT to one inoperable RHR Drywell Spray subsystem
  • Re-typed (Clean) TS Pages not included
  • SNC proposing to include sample RICTs only for TS 3.8 Required Actions
  • TSTF-505 requires identification of risk managed actions (RMAs) for evaluation of electrical power systems; sample RICTs would be included with RMAs
  • SNC not aware of a requirement to include identification of RMAs or sample RICTs to other TSs 11

Variations (continued)

  • TS 3.3.6.1, 3.6.1.3, and 3.8.1 are re-formatted to maintain only first level logical connectors in Completion Times.
  • Maintains consistency with TS 1.2 requirements for nesting.
  • Revised format maintains intent of existing TS.
  • For example:

Current TS 3.3.6.1 Condition A:

CONDITION REQUIRED ACTION COMPLETION TIME A. One or more required A.1 Place channel in trip. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> for channels inoperable. Functions 2.a, 2.b, 6.b, 7.a, and 7.b AND 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> for Functions other than Functions 2.a, 2.b, 6.b, 7.a, and 7.b 12

Variations (continued)

Proposed TS 3.3.6.1 Condition A

  • Same intent as existing 3.3.6.1 Condition A (i.e.

12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> CT for Functions 2.a, 2.b, 6.b, 7.a, and 7.b; 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> CT for all other Functions)

  • Allows use of RICT without nesting logical connectors
  • Note excluding RICT for items not modeled in PRA (e.g. Functions 2.c, 2.d, 2.e, 6.a, 6.b, 7.a, and 7.b) 13

Variations (continued)

Proposed TS 3.5.1 Conditions C and D

  • Per PRA success criteria AND design basis success criteria, this is not a LOF Condition
  • LCO 3.0.3 provides 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to initiate action to place unit in Mode 2 in 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, Mode 3 in 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />, and Mode 4 in 37 hours4.282407e-4 days <br />0.0103 hours <br />6.117725e-5 weeks <br />1.40785e-5 months <br />
  • Similar to Vogtle and Farley reformatting made during their respective amendment request for risk-informed TS 14

HNP Electrical Distribution System - Simplified Diagram 15

Variations - Revision to TS 3.8.1 Current Unit 1 RA B.4.1 Proposed Unit 1 RA B.4.1

  • TS 3.8.1 Conditions rearranged to avoid Completion Time nesting
  • Due to shared systems (e.g. SGT, MCREC), and due to loads being supplied from opposite unit (e.g.

LPCI valve load centers), each Unit requires AC sources (e.g. a required EDG or offsite transmission network) from the opposite Unit

  • TS 3.8.1 includes Conditions for required AC sources from opposite unit
  • For inoperable Unit DG, TS allow 14 day CT provided swing DG is locked to that unit and provided maintenance restrictions (e.g.

required Operable systems and functions) are met 16

Loss of Function (LOF) Considerations

  • Some Instrumentation Conditions are TS 3.3.1.1 applicable when one or more channels are REQUIRED inoperable, which could represent a LOF CONDITION COMPLETION TIME ACTION
  • TSTF-505 suggests a Note to limit the C. One or more C.1 Restore 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> application of RICT Functions with RPS trip
  • Should a LOF exist, TS require entry into a RPS trip capability.

capability not separate Condition that does not have RICT maintained.

option. Using TS 3.3.1.1 as an example:

  • Should LOF exist for Condition A or Condition B, Condition C will also be entered
  • Condition C is more restrictive and precludes applying a RICT for LOF 17
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