Abstract

Fault trees (FT) and event trees (ET) are widely used in industry to model and evaluate the reliability of safety systems. This work seeks to analyze and estimate the core damage frequency (CDF) due to flow blockage (FB) and loss of coolant accident (LOCA) due to large rupture of primary circuit pipe with respect to a specific 10 MW Water-Water Research Reactor in Ghana using the FT and ET technique. Using FT, the following reactor safety systems: reactor protection system, primary heat removal system, isolation of the reactor pool, emergency core cooling system (ECCS), natural circulation heat removal, and isolation of the containment were evaluated for their dependability. The probabilistic safety assessment (PSA) Level 1 was conducted using a commercial computational tool, system analysis program for practical coherent reliability assessment (SAPHIRE) 7.0. The frequency of an accident resulting in severe core damage for the internal initiating event was estimated to be 2.51e − 4/yr for the large LOCA as well as 1.45e − 4/yr for FB, culminating in a total core damage frequency of 3.96e − 4/yr. The estimated values for the frequencies of core damage were within the expected margins of 1.0e − 5/yr to 1.0e − 4/yr and of identical sequence of the extent as found for similar reactors.

Highlights

  • Following the Fukushima accident, the International Scientific Community’s attention to unmitigated nuclear power plant (NPP) accidents and their mitigation has become a major highlight [1, 2]

  • Is paper uses the probabilistic safety analysis (PSA) technique to examine the probability of occurrence of an accident and evaluate its consequences, providing a numerical estimate to indicate how safe the water-water reactor (VVR) 10 MWth is. e PSA analysis is employed in approximating the risk cutback that could be accomplished by making alterations to the nuclear reactor design or the operation and maintenance practices

  • E series of occurrences that could result in fuel integrity loss or core damage and their frequency of occurrence were identified and quantified in PSA Level 1. is paper presents the results obtained as part of the probabilistic safety assessment (PSA) Level 1 conducted for the Science and Technology of Nuclear Installations

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Summary

Research Article

Analysis and Estimation of Core Damage Frequency of Flow Blockage and Loss of Coolant Accident: A Case Study of a 10 MW Water-Water Research Reactor-PSA Level 1. Fault trees (FT) and event trees (ET) are widely used in industry to model and evaluate the reliability of safety systems. Is work seeks to analyze and estimate the core damage frequency (CDF) due to flow blockage (FB) and loss of coolant accident (LOCA) due to large rupture of primary circuit pipe with respect to a specific 10 MW Water-Water Research Reactor in Ghana using the FT and ET technique. E probabilistic safety assessment (PSA) Level 1 was conducted using a commercial computational tool, system analysis program for practical coherent reliability assessment (SAPHIRE) 7.0. Using FT, the following reactor safety systems: reactor protection system, primary heat removal system, isolation of the reactor pool, emergency core cooling system (ECCS), natural circulation heat removal, and isolation of the containment were evaluated for their dependability. e probabilistic safety assessment (PSA) Level 1 was conducted using a commercial computational tool, system analysis program for practical coherent reliability assessment (SAPHIRE) 7.0. e frequency of an accident resulting in severe core damage for the internal initiating event was estimated to be 2.51e − 4/yr for the large LOCA as well as 1.45e − 4/yr for FB, culminating in a total core damage frequency of 3.96e − 4/yr. e estimated values for the frequencies of core damage were within the expected margins of 1.0e − 5/yr to 1.0e − 4/yr and of identical sequence of the extent as found for similar reactors

Introduction
Safety systems and safety function
No emergency ventilation in LOCA
Primary heat removal
Water valve fails stuck closed
Wrong weight WW
Diesel motor fails
Sensor fails to give a signal
Operator fails to connect hose Water valves fail stuck closed
Std Dev
Full Text
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