The Atomic Energy Regulatory Board (AERB) has published a new Safety Guide on Deterministic Safety Analysis (DSA) for Water Cooled Reactors (WCR), encompassing Boiling Water Reactors (BWR), Pressurized Heavy Water Reactors (PHWR), and Pressurized Water Reactors (PWR). This guide was issued on January 13, 2025.
This guide aims to standardize the methodology for conducting safety analysis and replaces the previous guide specific to PHWRs (AERB/NPP-PHWR/SG/D-19).
Key Objectives and Scope
The primary objective of this Safety Guide is to provide recommendations and guidance on performing DSA for WCR-based nuclear power plants (NPPs). The guide aims to standardize the methodology to meet the safety requirements outlined in AERB Safety Codes related to:
- Siting
- Design
- Operation
- Management of nuclear and radiological emergencies
The scope of the guide covers various aspects of DSA, including:
- Different approaches for conducting DSA
- Safety analysis rules
- Acceptance criteria for various plant states (Normal Operation, Anticipated Operational Occurrences, Design Basis Accidents, and Design Extension Conditions)
- Verification and validation of computer codes used for DSA
- Presentation of results
- Documentation and updating of safety analysis
Key Changes and Focus Areas
The new guide applies to all WCR types (BWR, PHWR, and PWR), unlike the previous guide, which focused solely on PHWRs. The guide emphasizes standardizing the methodology for conducting safety analysis to ensure consistency and compliance with AERB safety codes.
It is applicable for DSA carried out as part of licensing requirements for Preliminary Safety Analysis Reports (PSAR), Final Safety Analysis Reports (FSAR), Periodic Safety Reviews (PSR), and submissions supporting modifications in operating NPPs.
Additionally, the guide primarily focuses on neutronics, thermal hydraulics, fuel behavior, source term estimation, and dose evaluation. It does not cover aspects like structural mechanics or electrical transients.
Guidance on methodology for selecting events to be analyzed should be referred from the AERB Safety Guide on ‘Design Basis Events for Water Cooled Nuclear Power Plants’ (AERB/NPP-WCR/SG/D-5, Rev.1).
The guide clarifies that DSA and safety analysis are used interchangeably. The guide also emphasizes the need to update safety analysis in light of significant changes in NPP configuration, operational experience, improved technical knowledge, changes in operating parameters, and to ensure consistency with the ‘as-built’ and ‘as-operated’ state of the plant.
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