scholarly journals Application of REPAS Methodology to Assess the Reliability of Passive Safety Systems

2009 ◽  
Vol 2009 ◽  
pp. 1-18 ◽  
Author(s):  
Franco Pierro ◽  
Dino Araneo ◽  
Giorgio Galassi ◽  
Francesco D'Auria
Keyword(s):  
Monte Carlo ◽  
Safety Assessment ◽  
Probability Distributions ◽  
Passive Safety ◽  
Passive System ◽  
Passive Systems ◽  
Passive Safety Systems ◽  
Passive Safety System ◽  
Uncertain Input ◽  
Safety Systems

The paper deals with the presentation of the Reliability Evaluation of Passive Safety System (REPAS) methodology developed by University of Pisa. The general objective of the REPAS is to characterize in an analytical way the performance of a passive system in order to increase the confidence toward its operation and to compare the performances of active and passive systems and the performances of different passive systems. The REPAS can be used in the design of the passive safety systems to assess their goodness and to optimize their costs. It may also provide numerical values that can be used in more complex safety assessment studies and it can be seen as a support to Probabilistic Safety Analysis studies. With regard to this, some examples in the application of the methodology are reported in the paper. A best-estimate thermal-hydraulic code, RELAP5, has been used to support the analyses and to model the selected systems. Probability distributions have been assigned to the uncertain input parameters through engineering judgment. Monte Carlo method has been used to propagate uncertainties and Wilks' formula has been taken into account to select sample size. Failure criterions are defined in terms of nonfulfillment of the defined design targets.

Integration of Passive System Reliability in PSA Studies

2006 ◽  
Author(s):  
Luciano Burgazzi ◽  
Michel Marques
Keyword(s):  
Safety Assessment ◽  
Natural Circulation ◽  
Fault Tree ◽  
Passive Safety ◽  
Passive System ◽  
Passive Systems ◽  
Probabilistic Safety Assessment ◽  
Passive Safety Systems ◽  
Safety Systems ◽  
Probabilistic Safety

The treatment of passive safety systems within the probabilistic safety assessment models is a difficult and challenging task. The main concern arises from the nature of the passive systems whose predominant operating principles are based on physical phenomena rather than on active components. The present study provides a consistent approach for the integration of passive safety systems into fault tree and event tree based Probabilistic Safety Assessment (PSA) model of accident sequences, in the fashion of and in combination with a front line system or a human action. With reference to the thermal-hydraulic passive systems (e.g. natural circulation systems), in addition to the component failures (i.e. mechanical and electrical faults), the impairment of the physical principle upon which the system relies, deserves special consideration. This makes the relative assessment process different as regards the system model commonly adopted in the fault tree approach (i.e. exponential failure model). For the thermal-hydraulic passive system, since the failure process is driven mainly by the occurrence of the phenomenological failure modes, each pertinent basic event will be characterized by defined critical parameters (e.g. non-condensable fraction) that are expected to drive the failure mechanisms. An application of this approach is presented, with reference to a system designed for decay heat removal of advanced Light Water Reactors, relying on natural circulation and provided with a heat exchanger immersed in a cooling pool, acting as heat sink, and connected to the pressure vessel via steam and condensate lines.

Investigation of effects of nonavailability of passive safety systems on the reactor behaviour during LOCA Scenario in AP600

Kerntechnik ◽  
2021 ◽  
Vol 86 (3) ◽  
pp. 244-255
Author(s):  
S. H. Abdel-Latif ◽  
A. M. Refaey
Keyword(s):  
Passive Safety ◽  
Primary System ◽  
Water Storage Tank ◽  
The Core ◽  
Passive Safety Systems ◽  
Loss Of Coolant Accident ◽  
Passive Safety System ◽  
Stage 4 ◽  
Core Cooling ◽  
Safety Systems

Abstract The AP600 is a Westinghouse Advanced Passive PWR with a two–loop 1 940 MWt. This reactor is equipped with advanced passive safety systems which are designed to operate automatically at desired set-points. On the other hand, the failure or nonavailability to operate of any of the passive safety systems may affect reactor safety. In this study, modeling and nodalization of primary and secondary loops, and all passive reactor cooling systems are conducted and a 10-inch cold leg break LOCA is analyzed using ATHLET 3.1A Code. During loss of coolant accident in which the passive safety system failure or nonavailability are considered, four different scenarios are assumed. Scenario 1 with the availability of all passive systems, scenario 2 is failure of one of the accumulators to activate, scenario 3 is without actuation of the automatic depressurization system (ADS) stages 1–3, and scenario 4 is without actuation of ADS stage 4. Results indicated that the actuation of passive safety systems provide sufficient core cooling and thus could mitigate the accidental consequence of LOCAs. Failure of one accumulator during LOCA causes early actuation of ADS and In-Containment Refueling Water Storage Tank (IRWST). In scenario 3 where the LOCA without ADS stages 1–3 actuations, the depressurization of the primary system is relatively slow and the level of the core coolant drops much earlier than IRWST actuation. In scenario 4 where the accident without ADS stage-4 activation, results in slow depressurization and the level of the core coolant drops earlier than IRWST injection. During the accident process, the core uncovery and fuel heat up did not happen and as a result the safety of AP600 during a 10-in. cold leg MBLOCA was established. The relation between the cladding surface temperature and the primary pressure with the actuation signals of the passive safety systems are compared with that of RELAP5/Mode 3.4 code and a tolerable agreement was obtained.

scholarly journals Experimental investigation of LWR passive safety systems performance at the INKA test facility

2019 ◽  
Vol 137 ◽  
pp. 01035
Author(s):  
Rafał Bryk ◽  
Thomas Mull ◽  
Holger Schmidt
Keyword(s):  
Test Facility ◽  
Passive Safety ◽  
Light Water Reactors ◽  
Passive Systems ◽  
Actual Performance ◽  
Passive Safety Systems ◽  
Original Plant ◽  
Water Reactors ◽  
Original Objective ◽  
Safety Systems

INKA is a test facility designed by Framatome and built in the technical center in Karlstein. The original objective for establishing this test rig was the investigation of the performance of the passive safety systems developed in a new Framatome Boiling Water Reactor (BWR) design – KERENA. INKA was constructed in the scale of 1:1 in heights while the total volume of the containment was replicated in 1:24. Since the geometries of particular safety systems are faithfully reflected, their actual performance in the original plant can be investigated at the full scale. Due to the unquestionable interest of the nuclear community in the inherent safety, not only new BWR and PWR designs are equipped with the passive systems, but also particular passive solutions are considered to be applied into the already existing Light Water Reactors (LWR). In this context and due to the fact that both, single component tests and integral tests can be conducted at INKA, the facility can be employed for a demonstration/qualification of a large range of passive safety systems foreseen for quite different types of LWRs. Hence, the goal of the EASY project was the experimental confirmation of the passive systems performance and the analysis of their interactions between each other in the integral tests. Besides, the overarching target of all tests performed at INKA is provision of data for codes validation. This paper presents major outcomes and conclusions drawn on the basis of EASY project results.

Dependency Analysis of Critical Parameters Influencing the Reliability of Thermal-Hydraulic Nuclear Passive Systems

2017 ◽  
Author(s):  
Samuel Abiodun Olatubosun ◽  
Zhijian Zhang
Keyword(s):  
Nuclear Power ◽  
Critical Parameters ◽  
Passive Safety ◽  
Distribution Analysis ◽  
Passive Systems ◽  
Research Issues ◽  
Passive Safety Systems ◽  
Influencing Parameters ◽  
Safety Systems ◽  
Nuclear Applications

The deployment of passive safety systems in nuclear applications especially in advanced nuclear power reactors (both evolutionary and innovative designs) is on the rise. This can be linked to the simplicity, economic and less dependence on human interventions attributes of those passive systems. The reliability of nuclear passive systems especially the thermal-hydraulic ones is influenced by parameters which are interdependent in reality. As a result, the need to critically consider the synergetic effects of determinants of reliability of the thermal-hydraulic nuclear passive systems is of utmost importance. Reliability methodologies are now being modified by factoring the dependency nature of those determinants into reliability analysis to obtain more realistic and accurate results. This paper thus focused on the introduction of more influencing factors in parameters dependency consideration of phenomenological reliability using multivariate distribution analysis. A passively water cooled steam generator was used to demonstrate the interdependency effects of some selected critical parameters. The results obtained justified the need for considering the dependency effects of these parameters influencing the reliability of thermal-hydraulic passive systems. In addition, the research issues on dependency consideration of influencing parameters in evaluation of reliability of these nuclear passive systems were also discussed.

scholarly journals Onshore Nuclear Power Plant Concept with Enhanced Passive Safety System

2019 ◽  
Vol 4 (6) ◽  
pp. 155-159
Author(s):  
A.H.M. Iftekharul Ferdous ◽  
T. H. M Sumon Rashid ◽  
Md Asaduzzaman Shobug ◽  
Tanveer Ahmed ◽  
Nitol Kumar Dutta
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Nuclear Power ◽  
Power Plants ◽  
Water Source ◽  
Passive Safety ◽  
Electric Power Supply ◽  
Passive Safety Systems ◽  
Passive Safety System ◽  
Safety Systems

Bangladesh is a developing country and it’s increasing economy can be maintained by providing sufficient amount of electric power supply. Therefore government is initiating Rooppur nuclear power project is one of them which is needed to be sited beside a vast amount of water source, lowest populated area and away from the locality to reduce the damage caused by any nuclear accidents. In this thesis paper we have shown that, the the dangers of residing errors of Rooppur nuclear power plant and give a proposal to go for onshore nuclear power plant in Bangladesh with two proposed designs of passive safety systems PSS-I & PSS-II. These systems will give safety to the power plants in the case of plant blackout during accidents.

scholarly journals Experiment for Justification the Reliability of Passive Safety System in NPP

2018 ◽  
Vol 3 (3) ◽  
pp. 1
Author(s):  
D.S. Samokhin ◽  
Mohammad Alslman ◽  
A. D. Vostrilova ◽  
O.Yu. Kochnov
Keyword(s):  
Power Systems ◽  
Nuclear Power ◽  
Critical Issue ◽  
Nuclear Industry ◽  
Passive Safety ◽  
Mathematical Methods ◽  
Mean Time Between Failures ◽  
Passive Safety Systems ◽  
Passive Safety System ◽  
Safety Systems

This article gives an overview of the formation of the global nuclear industry, highlighted a critical issue of ensuring safe operation of nuclear power systems in modern projects. Considering the use of passive safety systems in the design of a nuclear power plant, and discussed the different mathematical methods for assessing the reliability of passive systems. Also it considers the possibility of finding the mean time between failures, using these methods to assess the reliability of passive safety systems.

scholarly journals Reliability Assessment of Passive Safety Systems for Nuclear Energy Applications: State-of-the-Art and Open Issues

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4688
Author(s):  
Francesco Di Maio ◽  
Nicola Pedroni ◽  
Barnabás Tóth ◽  
Luciano Burgazzi ◽  
Enrico Zio
Keyword(s):  
Nuclear Power ◽  
Reliability Assessment ◽  
Nuclear Industry ◽  
Passive Safety ◽  
Passive Systems ◽  
Empirical Modelling ◽  
Energy Applications ◽  
Passive Safety Systems ◽  
Safety Systems ◽  
Open Issues

Passive systems are fundamental for the safe development of Nuclear Power Plant (NPP) technology. The accurate assessment of their reliability is crucial for their use in the nuclear industry. In this paper, we present a review of the approaches and procedures for the reliability assessment of passive systems. We complete the work by discussing the pending open issues, in particular with respect to the need of novel sensitivity analysis methods, the role of empirical modelling and the integration of passive safety systems assessment in the (static/dynamic) Probabilistic Safety Assessment (PSA) framework.

scholarly journals The Investigation of Nonavailability of Passive Safety Systems Effects on Small Break LOCA Sequence in AP1000 Using RELAP5 MOD 4.0

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Anwar Hussain ◽  
Amjad Nawaz
Keyword(s):  
Active Region ◽  
Reactor Core ◽  
Passive Safety ◽  
Primary System ◽  
Passive Safety Systems ◽  
Passive Safety System ◽  
Stage 4 ◽  
Loss Of Coolant ◽  
Core Cooling ◽  
Safety Systems

The passive safety systems of AP1000 are designed to operate automatically at desired set-points. However, the unavailability or failure to operate of any of the passive safety systems will change the accident sequence and may affect reactor safety. The analysis in this study is based on some hypothetical scenarios, in which the passive safety system failure is considered during the loss of coolant accidents. Four different cases are assumed, that is, with all passive systems, without actuation of one of the accumulators, without actuation of ADS stages 1–3, and without actuation of ADS stage 4. The actuation of all safety systems at their actuation set-points provides adequate core cooling by injecting sufficient water inventory into reactor core. The LOCA with actuation of one of the accumulators cause early actuation of ADS and IRWST. In case of LOCA without ADS stages 1–3, the primary system depressurization is relatively slow and mixture level above core active region drops much earlier than IRWST actuation. The accident without ADS stage 4 actuation results in slow depressurization and mixture level above core active region drops earlier than IRWST injection. Moreover, the comparison of cladding surface temperature is performed in all cases considered in this work.

Injury Criteria Based Optimisation of Automobile Passive Safety Systems to Mitigate the Effects of Full-Frontal Automobile Collisions

2014 ◽  
Author(s):  
Volkan Esat
Keyword(s):  
Interior Design ◽  
Simulation Software ◽  
Safety System ◽  
Passive Safety ◽  
Steering Wheel ◽  
System Parameters ◽  
Passive Safety Systems ◽  
Injury Criteria ◽  
Passive Safety System ◽  
Safety Systems

Passive safety systems such as airbags, seat belts, and interior structural design of the automobile play a significant role in injury prevention of the occupant during collisions. Important design and operation parameters of the passive safety systems such as airbag firing times and steering wheel position as an interior design attribute potentially affect the dynamics of the occupant during impact and determine the amount of mitigation of a possible injury. This research aims to contribute towards improving passive safety systems in automobile design for mitigation of injuries by optimising the features and parameters of various subsystems such as driver’s airbag and steering wheel. Two separate computational models, a 5th percentile female and a 50th percentile male, comprising of a typical automobile interior with passive safety systems are constructed in the specialised impact simulation software MADYMO. Two different crash pulses of 30 kph and 48 kph are applied to the computational human body models in full-frontal crashes. Passive safety system parameters; in particular, airbag firing times and steering wheel column angles, are varied to investigate their effects on the head, neck and upper torso through injury criteria. Injury criteria predictions are employed in optimisation algorithms to figure out the best combinations for passive safety system parameters in order to mitigate possible injuries for all drivers.

scholarly journals PECULIARITIES OF CONDUCTING FORENSIC RESEARCH ON PASSENGER SRS VEHICLE SYSTEM TO ESTABLISH THE REASON NOT CAUSE THE FRONT BUCKLES

2019 ◽  
Vol 19 (1) ◽  
pp. 309-319
Author(s):  
V. Varlahov ◽  
A. Lubentsov
Keyword(s):  
Technical Condition ◽  
Safety System ◽  
Passive Safety ◽  
Vehicle Electrical System ◽  
Passive Safety Systems ◽  
Road Users ◽  
Passive Safety System ◽  
The One ◽  
Safety Systems ◽  
Serious Injuries

Issues that arise from experts during the performance of court automotive expert assessments (expert researches) of technical condition of automobiles are considered, namely: SRS passive safety systems. The sequence of carrying out elemental research of the passive safety system of the SRS of cars on establishing the reasons for failure of the front (front) airbag of the passenger during a traffic accident is presented. The urgency of this paper is due, on the one hand, to the mass installation of airbags on cars of different brands, which are intended to protect the driver and passengers of vehicles from injuries during a collision, and on the other hand, frequent cases of not triggering airbags in the collision, associated as both for technical and operational reasons, resulting in serious injuries to the driver and passengers in the event of a collision. The increase in the level of constructive safety of the car, above all, is ensured by strengthening the requirements for the development, installation of structural elements and systems that provide protection of life and health of road users. Given the diversity of sources of risk factors for road accidents, constructive safety is divided into active, passive and after emergency. The examination of the technical condition of the SRS passive safety system is essentially a study of the vehicle electrical system requiring safety measures, since damage to the insulation of wires, shorting of individual circuits of electrical wires, and the introduction of extraneous current to the connectors can lead to the deployment of airbags during research.

Sign in / Sign up

Export Citation Format

Share Document