Developing a method for time-variant reliability assessment of passive heat removal systems in nuclear power plants. (15th September 2021)

• Record Type: Journal Article
• Authors: Ebrahimian, M.; Pirouzmand, A.; Rabiee, A.
• Is Part Of: Annals of nuclear energy. Volume 160(2021)
• Publication Date: 2021-09-15
• Subjects: AC Alternating current -- AEOI Atomic Energy Organization of Iran -- AHWR Advanced Heavy-Water Reactor -- APSRA Analysis of Passive Systems Reliability -- BNPP Bushehr Nuclear Power Plant -- CDF Cumulative Distribution Function -- DG Diesel Generator -- DN Nominal Diameter -- FORM First Order Reliability Method -- GFR Gas-cooled Fast Reactor -- GIF Generation IV International Forum -- HL-RF Hasofer Lind–Rackwitz Fiessler -- IAEA International Atomic Energy Agency -- ICS Isolation Condenser System -- NPP Nuclear Power Plant -- PCCS Passive Containment Cooling System -- PDF Probability Density Function -- PHRS Passive Heat Removal System -- PSAR Preliminary Safety Analysis Report -- RCP Reactor Coolant Pump -- REPAS Reliability Evaluation of the Passive Safety Systems -- RELAP Reactor Excursion and Leak Analysis Program -- RMPS Reliability Methodology for Passive Safety Systems -- SBO Station Black Out -- SBWR Simplified Boiling Water Reactor -- SG Steam Generator -- TDV Time Dependent Volume -- VVER Water-Water Energetic Reactor; Passive safety systems -- Time-variant reliability -- FORM -- PHI2 -- PHRS -- VVER-1000; Nuclear energy -- Periodicals; Nuclear engineering -- Periodicals; 621.4805
• DOI: 10.1016/j.anucene.2021.108365
• Languages: English
• ISSNs: 0306-4549

Abstract

Highlights: A new algorithm is proposed to evaluate the time-variant reliability of the PHRS in NPPs. The methodology is applied to evaluate the reliability of VVER-1000′s PHRS. Failure probability of passive safety systems is significant in terms of amplitude and its variation over time. The new algorithm can be easily incorporated into PSA methodology for risk analysis of new generation NPPs. Abstract: Nowadays, the use of passive safety systems is considered as the most important candidate to improve the safety level of new generation nuclear power plants. However, the functioning parameters of the passive systems vary significantly over time and are extremely tied to uncertainty. Time dependency may be due to the changes in certain and uncertain parameters and the mission of the passive systems. In this paper, a time-variant reliability analysis method that combines the out-crossing approach (PHI2) and the first-order reliability method (FORM) is developed and applied to analyze the passive heat removal system (PHRS) of VVER-1000 NPP as a case study. The thermo-hydraulic model of the PHRS and its related parameters besides the solving process of PHRS parameters in the PHI2 method are illustrated. The cumulative failure probability of the PHRS is calculated in terms of the system functioning parameters. The results of this study demonstrate that the failure probability of passive safety systems is significant in terms of amplitude and its variation over time and must be considered in the design and operation of these systems in the nuclear industry.