ML21098A128

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1D - Modeling Overview
ML21098A128
Person / Time
Issue date: 04/06/2021
From: Gabe Taylor
Office of Nuclear Regulatory Research
To:
Kenneth Hamburger
Shared Package
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Download: ML21098A128 (7)


Text

Modeling Overview Gabriel Taylor, P.E.

Office of Nuclear Regulatory Research

HEAF Research Working Group Update - April 6th, 2021 Overview of ZOI development 2

Scenario Current Duration Equipment Config.

Material Modeling Incident Energy Heat Flux Fragility Target Vulnerability Threshold ZOI Tables

+

=

Zone of Influence (ZOI)

HEAF Research Working Group Update - April 6th, 2021 Flashback : April 2018 3

Merging with incorporation of CFD modeling insights

HEAF Research Working Group Update - April 6th, 2021 Modeling Approaches

  • SNL SIERRA Suite

- Multi-physics coupled model

- Focus on modeling arc (source term)

- CFD modeling

- Focus on modeling thermal transport to target

  • Empirical

- Data fit

- Focus on specific phenomena; enclosure breach, arc voltage 4

HEAF Research Working Group Update - April 6th, 2021 Modeling Scenarios 5

  • Medium Voltage, Non-segregated phase bus duct

Enclosure:

Steel or Aluminum

- Conductors: Aluminum or Copper

  • Medium Voltage Switchgear

- Configuration: Supply, Main, Load

- Energy Profile: Stiff, Decay, or Stiff + Decay

- Conductors: Aluminum or Copper

  • Low Voltage Switchgear

- Conductors: Aluminum or Copper

HEAF Research Working Group Update - April 6th, 2021 Scenario Consolidation

  • PRA document covers over 300 scenarios for just aluminum
  • Low energy scenarios are being removed from initial list using empirical correlations and slightly conservative fragility thresholds
  • Reduces scenario list by 88%
  • Some scenarios have similar or identical hazard and can be consolidated even further 6

HEAF Research Working Group Update - April 6th, 2021 Summary

  • Overall approach to decouple modeling and fragility efforts remains intact
  • Modeling approach has evolved into a hybrid between category and dynamic
  • PRA guidance document supports defining model scenarios
  • Modeling appears to provide reasonable estimates to inform the working groups ZOI determination. However, areas for uncertainty reduction exist.

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