Round-robin study of a priori modelling predictions of the Dalmarnock Fire Test One

Quantifying differences between computational results and measurements in the case of a large-scale well-confined fire scenario

Im Rahmen dieser Arbeit erfolgt die Ableitung einer energiebasierten Brandlast fur Tunnel mittels CFD. Eine energiebasierte Brandlast ermoglicht es in der Planung und Nachrechnung von technisch geregelten Temperatur-Zeit-Kurven abzuweichen und damit den Ansatz realer Brandlasten. Diese unnelindividuellen Brandlasten werden uber eine transiente thermisch-mechanisch gekoppelte Mehrphasen-FEM-Simulation auf unbewehrte Tunnelschalen aus Beton unter Berucksichtigung der dauerhaften thermischen Materialschadigung nach einer Temperaturbeanspruchung angesetzt.

Zur Traglastberechnung kreisförmiger, unterirdischer Strukturen im Hochtemperaturbereich

Energy balance in a large compartment fire

An integrated methodology for spatio-temporal incorporation of underlying failure mechanisms into fire probabilistic risk assessment of nuclear power plants

During the 1990s, the Electric Power Research Institute (EPRI) developed methods for fire risk analysis to support its utility members in the preparation of responses to Generic Letter 88-20, Supplement 4, 'Individual Plant Examination - External Events' (IPEEE). This effort produced a Fire Risk Assessment methodology for operations at power that was used by the majority of U.S. nuclear power plants (NPPs) in support of the IPEEE program and several NPPs overseas. Although these methods were acceptable for accomplishing the objectives of the IPEEE, EPRI and the U.S. Nuclear Regulatory Commission (NRC) recognized that they required upgrades to support current requirements for risk-informed, performance-based (RI/PB) applications. In 2001, EPRI and the USNRC's Office of Nuclear Regulatory Research (RES) embarked on a cooperative project to improve the state-of-the-art in fire risk assessment to support a new risk-informed environment in fire protection. This project produced a consensus document, NUREG/CR-6850 (EPRI 1011989), entitled 'Fire PRA Methodology for Nuclear Power Facilities' which addressed fire risk for at power operations. NUREG/CR-6850 developed high level guidance on the process for identification and inclusion of human failure events (HFEs) into the fire PRA (FPRA), and a methodology for assigning quantitative screening values to these HFEs. It outlinedmore » the initial considerations of performance shaping factors (PSFs) and related fire effects that may need to be addressed in developing best-estimate human error probabilities (HEPs). However, NUREG/CR-6850 did not describe a methodology to develop best-estimate HEPs given the PSFs and the fire-related effects. In 2007, EPRI and RES embarked on another cooperative project to develop explicit guidance for estimating HEPs for human failure events under fire generated conditions, building upon existing human reliability analysis (HRA) methods. This document provides a methodology and guidance for conducting a fire HRA. This process includes identification and definition of post-fire human failure events, qualitative analysis, quantification, recovery, dependency, and uncertainty. This document provides three approaches to quantification: screening, scoping, and detailed HRA. Screening is based on the guidance in NUREG/CR-6850, with some additional guidance for scenarios with long time windows. Scoping is a new approach to quantification developed specifically to support the iterative nature of fire PRA quantification. Scoping is intended to provide less conservative HEPs than screening, but requires fewer resources than a detailed HRA analysis. For detailed HRA quantification, guidance has been developed on how to apply existing methods to assess post-fire fire HEPs.« less

EPRI/NRC-RES Fire Human Reliability Analysis Guidelines

Verification and Validation--How to Determine the Accuracy of Fire Models. | NIST

Fire ignition frequency is the first quantitative measure of fire risk. Different models have been employed by the industry to estimate the frequency of fire occurrence at different locations within a plant. Earlier models provided frequencies by building type (e.g., auxiliary building and turbine building) and specific rooms (e.g., control room and cable spreading room). In the later models, fire ignition frequencies were estimated by equipment type. As fire event database expanded, a combined model was developed that combined location specific information with equipment type. In the Fire Risk Requantification Study, the latter model was further enhanced in terms of combined categories of location and equipment type and enhanced use of the information provided in event reports of the underlying database. Two-stage Bayesian approach was used to characterize the plant-to-plant variability uncertainties in the fire ignition frequencies and facilitate incorporation of plant specific information.

Fire Risk Requantification Study — Fire Ignition Frequencies

The U.S. Nuclear Regulatory Commission (NRC) Office ofNuclear Regulatory Research (RES) and the Electric Power Research Institute (EPRI), in cooperation with nuclear power generating utilities in the U.S., have embarked on a joint effort to document and demonstrate state of the art methods in fire probabilistic risk assessment (PRA). One principal objective of this project is to resolve methodological issues affecting the application of fire PRA methods. This paper discusses current work in progress to establish new fire modeling approaches that appropriately address dependencies with other analysis tasks and include an explicit treatment of fire severity.

Bijan Najafi

Papers

EPRI/NRC-RES Fire Human Reliability Analysis Guidelines

Verification and Validation--How to Determine the Accuracy of Fire Models. | NIST

Fire Risk Requantification Study — Fire Ignition Frequencies

Methods Advances in the EPRI/USNRC Fire Risk Requantification Study — Fire Modeling

Methods advances in the EPRI/USNRC fire risk requantification study.