The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Samad Khakshournia - One of the best experts on this subject based on the ideXlab platform.
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A liquid injection based Second Shutdown System for a typical material testing research reactor
Annals of Nuclear Energy, 2018Co-Authors: Ehsan Boustani, Samad KhakshourniaAbstract:Abstract Many research reactors are used all over the world. There is a higher probability of accidents in nuclear research reactors compared their wide applications in a broad spectrum of sciences and industries. Material Testing Reactor (MTR) type is one large species of nuclear research reactors. Safety criteria are of main concern issues in the entire nuclear research reactor lifetime to satisfy the defense in depth criteria. In this paper, the main focus is on Second Shutdown System (SSS) as an Engineered Safety Feature (ESF) considered to enhance safety which will transfer the reactor to a subcritical state at actuation of any command circuits when a specific parameters exceeds some pre-established set points. Tehran Research Reactor (TRR) is selected as an MTR case study and one SSS is designed and studied in detail using MCNPX 2.6.0 code with regard to its requirements. It turns out that this SSS improves the overall reactor safety, and has not considerable penalties on different capabilities and characteristics of the reactor such as neutronic characteristics, safety criteria, and performance applications.
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Enhancing Tehran Research Reactor safety through a Second Shutdown System: A probabilistic safety assessment
Progress in Nuclear Energy, 2017Co-Authors: Ehsan Boustani, Samad KhakshourniaAbstract:Abstract One of the conceivable safety features for enhancing safety of a research reactor such as the Tehran Research Reactor (TRR) is a Second Shutdown System (SSS). One innovative SSS is designed with considering the TRR requirements and limitations such as safety, operational problems, neutronic and aging problems. The SSS of TRR is a reliable, independent and diverse Shutdown System which can actuate and shut down the reactor following the First Shutdown System (FSS) failure. In the present study, the effect of this new option on upgrading the reactor safety is studied with performing level 1 of Probabilistic Safety Assessment (PSA) using the SAPHIRE code based on the selected initiating events. PSA is increasingly being used as a part of the decision making process to assess the level of safety of nuclear reactors. Considering only internal events in this analysis, it is seen that with the existence of the SSS the failure rate of reactor Shutdown System decreases at least to 3.20E-04 of its previous value. The core damage frequency conservatively turns out to decrease at least by the half of the value previously reported to be 8.37E-06/y. In order to enhance the TRR, reactor personnel and other public safety, equipping TRR with a SSS is a rational plan. To avoid accidents which can cause mass environmental damage and human loss is the prime advantage of equipping TRR with this engineered safety feature.
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A pragmatic approach towards designing a second Shutdown System for Tehran research reactor
Nuclear Technology and Radiation Protection, 2016Co-Authors: Ehsan Boustani, Samad Khakshournia, Hossein KhalafiAbstract:One second Shutdown System is proposed for the Tehran Research Reactor to achieve the goal of higher safety in compliance with current operational requirements and regulations and improve the overall reliability of the reactor Shutdown System. The proposed second Shutdown System is a diverse, independent Shutdown System compared to the existing rod based one that intends to achieve and maintain sub-criticality condition with an enough Shutdown margin in many of abnormal situations. It is designed as much as practical based on neutron absorber solution injection into the existing core while the changes and interferences with the existing core structure are kept to a minimum. Core neutronic calculations were performed using MCNPX 2.6.0 and MTR_PC package for the current operational core equipped with the second Shutdown System, and one experiment was conducted in the Tehran Research Reactor to test the neutronic calculations. A good agreement was seen between theoretical results and experimental ones. In addition, capability of the second Shutdown System in the case of occurrence of design basis accident in the Tehran Research Reactor is demonstrated using PARET program.
Ehsan Boustani - One of the best experts on this subject based on the ideXlab platform.
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Neutronic design investigation of a liquid injection-based second Shutdown System for a typical research reactor using MCNPX
Nuclear Science and Techniques, 2018Co-Authors: Ehsan Boustani, Mostafa HassanzadehAbstract:Safety Systems, built on state-of-the-art technology, are essential for achieving acceptable levels of plant safety to minimize hazards to the reactor and the general public. The second Shutdown System (SSS) as an engineered safety feature and a part of the reactor protection System (RPS) is a means for rapidly shutting down a nuclear reactor, keeping it in a subcritical state and serving as a backup to the first Shutdown System (FSS). In this research, one SSS with two types of optimum chamber designs is proposed that take into account the main current characteristic features of the Tehran research reactor with improvements over earlier designs. They are based on a liquid neutron absorber injection that is preferably different, diverse, and independent from the FSS based on the rod drop mechanism. The major design characteristics of this SSS with two different chambers were investigated using MCNPX 2.6.0 code. The performed calculations showed that the designed SSS is a reliable Shutdown System, assuring an appropriate Shutdown margin and injection time, with no significant effects on the effective delayed neutron fraction while causing minimal variations to the core structure. Further, the reasonable financial cost and the prolongation of the operation cycle are additional advantages of this design.
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A liquid injection based Second Shutdown System for a typical material testing research reactor
Annals of Nuclear Energy, 2018Co-Authors: Ehsan Boustani, Samad KhakshourniaAbstract:Abstract Many research reactors are used all over the world. There is a higher probability of accidents in nuclear research reactors compared their wide applications in a broad spectrum of sciences and industries. Material Testing Reactor (MTR) type is one large species of nuclear research reactors. Safety criteria are of main concern issues in the entire nuclear research reactor lifetime to satisfy the defense in depth criteria. In this paper, the main focus is on Second Shutdown System (SSS) as an Engineered Safety Feature (ESF) considered to enhance safety which will transfer the reactor to a subcritical state at actuation of any command circuits when a specific parameters exceeds some pre-established set points. Tehran Research Reactor (TRR) is selected as an MTR case study and one SSS is designed and studied in detail using MCNPX 2.6.0 code with regard to its requirements. It turns out that this SSS improves the overall reactor safety, and has not considerable penalties on different capabilities and characteristics of the reactor such as neutronic characteristics, safety criteria, and performance applications.
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Enhancing Tehran Research Reactor safety through a Second Shutdown System: A probabilistic safety assessment
Progress in Nuclear Energy, 2017Co-Authors: Ehsan Boustani, Samad KhakshourniaAbstract:Abstract One of the conceivable safety features for enhancing safety of a research reactor such as the Tehran Research Reactor (TRR) is a Second Shutdown System (SSS). One innovative SSS is designed with considering the TRR requirements and limitations such as safety, operational problems, neutronic and aging problems. The SSS of TRR is a reliable, independent and diverse Shutdown System which can actuate and shut down the reactor following the First Shutdown System (FSS) failure. In the present study, the effect of this new option on upgrading the reactor safety is studied with performing level 1 of Probabilistic Safety Assessment (PSA) using the SAPHIRE code based on the selected initiating events. PSA is increasingly being used as a part of the decision making process to assess the level of safety of nuclear reactors. Considering only internal events in this analysis, it is seen that with the existence of the SSS the failure rate of reactor Shutdown System decreases at least to 3.20E-04 of its previous value. The core damage frequency conservatively turns out to decrease at least by the half of the value previously reported to be 8.37E-06/y. In order to enhance the TRR, reactor personnel and other public safety, equipping TRR with a SSS is a rational plan. To avoid accidents which can cause mass environmental damage and human loss is the prime advantage of equipping TRR with this engineered safety feature.
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A pragmatic approach towards designing a second Shutdown System for Tehran research reactor
Nuclear Technology and Radiation Protection, 2016Co-Authors: Ehsan Boustani, Samad Khakshournia, Hossein KhalafiAbstract:One second Shutdown System is proposed for the Tehran Research Reactor to achieve the goal of higher safety in compliance with current operational requirements and regulations and improve the overall reliability of the reactor Shutdown System. The proposed second Shutdown System is a diverse, independent Shutdown System compared to the existing rod based one that intends to achieve and maintain sub-criticality condition with an enough Shutdown margin in many of abnormal situations. It is designed as much as practical based on neutron absorber solution injection into the existing core while the changes and interferences with the existing core structure are kept to a minimum. Core neutronic calculations were performed using MCNPX 2.6.0 and MTR_PC package for the current operational core equipped with the second Shutdown System, and one experiment was conducted in the Tehran Research Reactor to test the neutronic calculations. A good agreement was seen between theoretical results and experimental ones. In addition, capability of the second Shutdown System in the case of occurrence of design basis accident in the Tehran Research Reactor is demonstrated using PARET program.
Jin Jiang - One of the best experts on this subject based on the ideXlab platform.
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Potential improvement of CANDU NPP safety margins by shortening the response time of Shutdown Systems using FPGA based implementation
Nuclear Engineering and Design, 2012Co-Authors: Jingke She, Jin JiangAbstract:Abstract The relationship between the peak values of critical reactor variables, such as neutronic power, inside a CANDU reactor and the speed of the response of its Shutdown System has been analyzed in the event of a large loss of coolant accident (LOCA). The advantage of shortening the response time of the Shutdown action has been demonstrated in term of the improved safety margin. A field programmable gate array (FPGA) platform has been chosen to implement such a Shutdown System. Hardware-in-the-loop (HIL) simulations have been performed to demonstrate the feasibility of this concept. Furthermore, connections between the speed of response of the Shutdown System and the nominal operating power level of the reactor have been drawn to support for potential power upgrade for existing power plants.
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On the speed of response of an FPGA-based Shutdown System in CANDU nuclear power plants
Nuclear Engineering and Design, 2011Co-Authors: Jingke She, Jin JiangAbstract:Abstract Several issues in an FPGA based implementation of Shutdown Systems in CANDU nuclear power plants have been investigated in this paper. A particular attention is on the response time of an FPGA implementation of safety Shutdown Systems in comparison with operating System based software solutions as in existing CANDU plants. The trip decision logic under “steam generator (SG) level low” condition has been examined in detail. The design and implementation of this logic on an FPGA platform have been carried out. The functionality tests are performed in a hardware-in-the-loop (HIL) environment by connecting the FPGA based System to an NPP simulator, and replacing one channel of Shutdown System Number 1 (SDS1) in the simulator by the FPGA implementation. The response time of the designed System is also measured through multiple tests under different conditions, and statistical data analysis has been performed. The results of the response time tests are compared against those of a software-based implementation of the same trip logic.
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analysis of surveillance test interval by markov process for sds1 in candu nuclear power plants
Reliability Engineering & System Safety, 2008Co-Authors: Jin JiangAbstract:The Canadian Nuclear Safety Commission (CNSC) requires that each Shutdown System (SDS) of CANDU plant should be available more than 99.9% of the reactor operating time and be tested periodically. The compliance with the availability requirement should be demonstrated using the component failure rate data and the benefits of the tests. There are many factors that should be considered in determining the surveillance test interval (STI) for the SDSs. These includes: the desired target availability, the actual unavailability, the probability of spurious trips, the test duration, and the side effects such as wear-out, human errors, and economic burdens. A Markov process model is developed to study the effect of test interval in the Shutdown System number one (SDS1) in this paper. The model can provide the quantitative data required for selecting the STI. Representing the state transitions in the SDS1 by a time-homogeneous Markov process, the model can be used to quantify the effect of surveillance test durations and interval on the unavailability and the spurious trip probability. The model can also be used to analyze the variation of the core damage probability with respect to changes in the test interval once combined with the conditional core damage model derived from the event trees and the fault trees of probabilistic safety assessment (PSA) of the nuclear power plant (NPP).
G. Dragffy - One of the best experts on this subject based on the ideXlab platform.
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The design of a highly reliable safety critical emergency Shutdown System
Reliability Engineering & System Safety, 1998Co-Authors: G. DragffyAbstract:Abstract An emergency Shutdown System (ESD) by its nature should be fail-safe. That is, in case of failure in any of its operations, in order to safeguard human life, property and the environment, it should shut down the plant that it controls. However, a complete Shutdown, for example, of a petrochemical or nuclear plant is extremely costly. Therefore, as an alternative, the design of highly reliable emergency Shutdown Systems should be investigated. The major difference between a Shutdown System and other control Systems is the degree of tolerable operational integrity. A malfunction in the latter is immediately visible and the System can be replaced by a fully operational one. A Shutdown System on the other hand is usually, sometimes for years and hopefully forever, `dormant'. When, however, a true emergency situation arises and real demand is placed on it, it must be fully functional. Reliability is of paramount importance. Therefore, besides applying structured design techniques and improved testability other design methods will also need to be incorporated in the final System in order to increase its reliability.
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Hardware programmable VLSI emergency Shutdown System
Reliability Engineering & System Safety, 1998Co-Authors: G. DragffyAbstract:Abstract As the required intelligence of Systems increases so does their complexity, to the extent that their design is becoming less and less manageable. The issue of complexity explosion and its management during the product design phase is examined through the design and design implementation of a VLSI Emergency Shutdown System (ESD) chip. Highly structured Algorithmic State Machine (ASM) design techniques are used to achieve a hardware programmable and flexible implementation of the product specification. The chip is capable to monitor up to four but upward extendable process variables and activate a Shutdown operation if any one of the variables falls outside predetermined limits. It is supported by a single operator interface panel that controls and observes the operation of all channels. This paper, in two parts, describes the results of a research effort to design a general purpose VLSI ESD System which aims to achieve a level of reliability and testability exceeding current implementations.
R.r. Bevins - One of the best experts on this subject based on the ideXlab platform.
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Requirements Analysis Study for Master Pump Shutdown System Project Development Specification [SEC 1 and 2]
2000Co-Authors: R.r. BevinsAbstract:This study is a requirements document that presents analysis for the functional description for the master pump Shutdown System. This document identifies the sources of the requirements and/or how these were derived. Each requirement is validated either by quoting the source or an analysis process involving the required functionality, performance characteristics, operations input or engineering judgment. The requirements in this study apply to the first phase of the W314 Project. This document has been updated during the definitive design portion of the first phase of the W314 Project to capture additional software requirements and is planned to be updated during the second phase of the W314 Project to cover the second phase of the project's scope.
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Failure and Reliability Analysis for the Master Pump Shutdown System
2000Co-Authors: R.r. BevinsAbstract:The Master Pump Shutdown System (MPSS) will be installed in the 200 Areas of the Hanford Site to monitor and control the transfer of liquid waste between tank farms and between the 200 West and 200 East areas through the Cross-Site Transfer Line. The Safety Function provided by the MPSS is to Shutdown any waste transfer process within or between tank farms if a waste leak should occur along the selected transfer route. The MPSS, which provides this Safety Class Function, is composed of Programmable Logic Controllers (PLCs), interconnecting wires, relays, Human to Machine Interfaces (HMI), and software. These components are defined as providing a Safety Class Function and will be designated in this report as MPSS/PLC. Input signals to the MPSS/PLC are provided by leak detection Systems from each of the tank farm leak detector locations along the waste transfer route. The combination of the MPSS/PLC, leak detection System, and transfer pump controller System will be referred to as MPSS/SYS. The components addressed in this analysis are associated with the MPSS/SYS. The purpose of this failure and reliability analysis is to address the following design issues of the Project Development Specification (PDS) for the MPSS/SYS (HNF 2000a): (1) Single Component Failure Criterion, (2) System Status Upon Loss of Electrical Power, (3) Physical Separation of Safety Class cables, (4) Physical Isolation of Safety Class Wiring from General Service Wiring, and (5) Meeting the MPSS/PLC Option 1b (RPP 1999) Reliability estimate. The failure and reliability analysis examined the System on a component level basis and identified any hardware or software elements that could fail and/or prevent the System from performing its intended safety function.
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Requirements Analysis Study for Master Pump Shutdown System Project Development Specification [SEC 1 and 2]
2000Co-Authors: R.r. BevinsAbstract:This document has been updated during the definitive design portion of the first phase of the W-314 Project to capture additional software requirements and is planned to be updated during the second phase of the W-314 Project to cover the second phase of the Project's scope. The objective is to provide requirement traceability by recording the analysis/basis for the functional descriptions of the master pump Shutdown System. This document identifies the sources of the requirements and/or how these were derived. Each requirement is validated either by quoting the source or an analysis process involving the required functionality, performance characteristics, operations input or engineering judgment.