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Research paper thumbnail of Evolution of South African nuclear regulatory regime from the British nuclear regulatory system

This open-access article is distributed under the terms of the Creative Commons Attribution Non-C... more This open-access article is distributed under the terms of the Creative Commons Attribution Non-Commercial License (CC BY-NC) (http:// creativecommons.org/licenses/by-nc/4.0/), which permits reuse, distribution and reproduction of the article, provided that the original work is properly cited and the reuse is restricted to noncommercial purposes. For commercial reuse, contact reprints@pulsus.com Evolution of South African nuclear regulatory regime from the British nuclear regulatory system

Research paper thumbnail of Methodology for Licensing Burnup Creditin Nuclear Criticality Safety Analysis: ACalculational Basis

Research paper thumbnail of Preserving Spent Fuel Storage Capacity by Taking Credit for Burnup in Nuclear Criticality Safety Analysis: An Alternative Solution to Spent Fuel Storage Shortage

Research paper thumbnail of Time-dependent variation of the neutron multiplication factor in spent fuel storage

Kerntechnik, 2017

After spent fuel assemblies have been discharged from the reactor, reactivity will fluctuate as t... more After spent fuel assemblies have been discharged from the reactor, reactivity will fluctuate as the cooling period progresses because of changes in the number density of fissile nuclides and neutron absorber nuclides. The purpose of this project was (1) to quantify the contribution of each individual nuclide to the reactivity of the fissile system, (2) to identify nuclides that are responsible for the fluctuation in reactivity, and (3) to determine the effect of the number of nuclides on reactivity. This paper will present the results of the study of the behaviour of the keff with respect to variation in the duration of the cooling period during storage.

Research paper thumbnail of Sensitivity of the neutron multiplication factor to water ingress into a spent fuel cask

Kerntechnik, 2020

An essential component of safety analyses is the investigation of accident scenarios. In this pap... more An essential component of safety analyses is the investigation of accident scenarios. In this paper water ingress scenarios of spent fuel containers, as they may occur during transport or storage, are examined. In the main body of this paper, a number of paths are studied through which water can gain access to the spent fuel cask and eventually reach the fuel pellet, potentially resulting in an increase in reactivity as a result of over-moderation. The primary objective of this project was to perform an assessment of what, in the unlikely event of a Fukushima- type accident, the impact would be on the reactivity of the cask by analyzing a gradual increase in water level in the spent fuel casks. In addition, the way the keff of the system responds to such an increase is discussed. The paper also provides the results of an assessment of the reactivity effect of water ingress via various pathways/channels.

Research paper thumbnail of Prediction of dose rates around the interim spent fuel storage facility

Radiation Physics and Chemistry, 2020

This paper presents the results of radiation shielding analyses performed for siting of the Inter... more This paper presents the results of radiation shielding analyses performed for siting of the Interim Spent Fuel Storage Facility (ISFSF) with a view of determining what the radiation levels will be around the ISFSF when it is made up of a certain number of casks of a specific design ( Radulescu et al., 2018 ) ( Radiation Shielding Analy, 2004 ). It will also determine the equivalent neutron energy where each cell damage scenarios occurs as a result ionisation.

Research paper thumbnail of Investigation of the release of gaseous fission products from pebble bed molecular reactor's triso coated fuel particle during the HFR-K5 fuel irradiation test

Research paper thumbnail of Criticality safety analysis of the design of spent fuel cask, its manipulation and placement in a long-term storage

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fu... more A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015

Research paper thumbnail of Ranking of Aluminium Composite Materials for Use as Neutron Absorber Inserts in Spent Fuel Pools

A number of spent fuel pools at nuclear power stations that have been operating since the mid 198... more A number of spent fuel pools at nuclear power stations that have been operating since the mid 1980s or earlier are gradually approaching their full capacity. This puts pressure on the nuclear facility to develop strategies to increase the storage space of the spent fuel pool if untimely shut down is to be avoided. One of the methods that can be employed is to insert neutron-absorbing materials in the spent fuel pool with a view to reducing the number of thermal neutrons which cause fission. This will subsequently reduce the k eff of the system and permit a higher fuel storage density. This paper evaluates the suitability of the material used as neutron absorber inserts (or absorber inserts for short) and ranks several aluminium composite materials for use as absorber inserts on the basis of their effectiveness in decreasing the k eff of the system, thereby recovering some of the storage space consumed as a result of over-conservatism.

Research paper thumbnail of The Effects of Storage Patterns on the Neutron Multiplication Factor of Spent Nuclear Fuel Casks

The type of an array selected for the storage of fissile material such as fuel assemblies or spen... more The type of an array selected for the storage of fissile material such as fuel assemblies or spent fuel casks has a profound effect on the neutron multiplication factor (k eff ) of the system. Given a particular initial enrichment, the neutron multiplication factor of the system can either increase or decrease depending on either the type of the array used (which may either be an n x n , or n x m where n m ), the distance among various fissile units or the total number of units. This paper will present the effects of changes in distances between spent fuel casks in various storage arrays using fresh fuel assumptions.

Research paper thumbnail of Effects of the Location of a Misloaded Fuel Assembly on the Neutron Multiplication Factor of CASTOR X/28 F Spent Fuel Cask

Fuel assembly misload incidents represent a serious nuclear safety concern from a nuclear critica... more Fuel assembly misload incidents represent a serious nuclear safety concern from a nuclear criticality safety point of view, since they can potentially cause reactivity induced accidents (RIA) accidents with severe consequences. Misloads are a result of inadequate spent fuel management such as poor record keeping of important data of the spent fuel (e.g. the exact location of each fuel assembly in the spent fuel pool, the cooling period and burnup) which are crucial for decision whether they will be acceptable for cask loading or not. The cask under study is CASTOR X/28 F which is designed for fuel assemblies with a 10-year cooling period and the average enrichment of 3.25 wt%.

Research paper thumbnail of Sensitivity analysis of parameters important to nuclear criticality safety of Castor X/28F spent nuclear fuel cask

Kerntechnik, 2015

In nuclear criticality safety analysis it is essential to ascertain how various components of the... more In nuclear criticality safety analysis it is essential to ascertain how various components of the nuclear system will perform under certain conditions they may be subjected to, particularly if the components of the system are likely to be affected by environmental factors such as temperature, radiation or material composition. It is therefore prudent that a sensitivity analysis is performed to determine and quantify the response of the output to variation in any of the input parameters. In a fissile system, the output parameter of importance is the keff. Therefore, in attempting to prevent reactivity-induced accidents, it is important for the criticality safety analyst to have a quantified degree of response for the neutron multiplication factor to perturbation in a given input parameter. This article will present the results of the perturbation of the parameters that are important to nuclear criticality safety analysis and their respective correlation equations for deriving the sen...

Research paper thumbnail of Time-dependent variations in the radiological health impact of an interim spent fuel storage facility

Radiation Physics and Chemistry

Research paper thumbnail of Establishing an Effective Nuclear Regulatory Regime: A Case Study of South Africa

Science, Technology & Public Policy

Research paper thumbnail of The Effects of Storage Patterns on the Neutron Multiplication Factor of Spent Nuclear Fuel Casks

International Nuclear Safety Journal, Nov 19, 2012

The type of an array selected for the storage of fissile material such as fuel assemblies or spen... more The type of an array selected for the storage of fissile material such as fuel assemblies or spent fuel casks has a profound effect on the neutron multiplication factor (keff) of the system. Given a particular initial enrichment, the neutron multiplication factor of the system can either increase or decrease depending on either the type of the array used (which may either be an n x n, or n x m where nm), the distance among various fissile units or the total number of units. This paper will present the effects of changes in distances between spent fuel casks in various storage arrays using fresh fuel assumptions.

Research paper thumbnail of Preferential Water Ingress into a Dry Spent Fuel Cask

Journal of Nuclear Energy Science & Power Generation Technology

Research paper thumbnail of Preferential Water Ingress into a Dry Spent Fuel Cask

Journal of Nuclear Energy Science & Power Generation Technology

Research paper thumbnail of Evolution of South African nuclear regulatory regime from the British nuclear regulatory system

This open-access article is distributed under the terms of the Creative Commons Attribution Non-C... more This open-access article is distributed under the terms of the Creative Commons Attribution Non-Commercial License (CC BY-NC) (http:// creativecommons.org/licenses/by-nc/4.0/), which permits reuse, distribution and reproduction of the article, provided that the original work is properly cited and the reuse is restricted to noncommercial purposes. For commercial reuse, contact reprints@pulsus.com Evolution of South African nuclear regulatory regime from the British nuclear regulatory system

Research paper thumbnail of Methodology for Licensing Burnup Creditin Nuclear Criticality Safety Analysis: ACalculational Basis

Research paper thumbnail of Preserving Spent Fuel Storage Capacity by Taking Credit for Burnup in Nuclear Criticality Safety Analysis: An Alternative Solution to Spent Fuel Storage Shortage

Research paper thumbnail of Time-dependent variation of the neutron multiplication factor in spent fuel storage

Kerntechnik, 2017

After spent fuel assemblies have been discharged from the reactor, reactivity will fluctuate as t... more After spent fuel assemblies have been discharged from the reactor, reactivity will fluctuate as the cooling period progresses because of changes in the number density of fissile nuclides and neutron absorber nuclides. The purpose of this project was (1) to quantify the contribution of each individual nuclide to the reactivity of the fissile system, (2) to identify nuclides that are responsible for the fluctuation in reactivity, and (3) to determine the effect of the number of nuclides on reactivity. This paper will present the results of the study of the behaviour of the keff with respect to variation in the duration of the cooling period during storage.

Research paper thumbnail of Sensitivity of the neutron multiplication factor to water ingress into a spent fuel cask

Kerntechnik, 2020

An essential component of safety analyses is the investigation of accident scenarios. In this pap... more An essential component of safety analyses is the investigation of accident scenarios. In this paper water ingress scenarios of spent fuel containers, as they may occur during transport or storage, are examined. In the main body of this paper, a number of paths are studied through which water can gain access to the spent fuel cask and eventually reach the fuel pellet, potentially resulting in an increase in reactivity as a result of over-moderation. The primary objective of this project was to perform an assessment of what, in the unlikely event of a Fukushima- type accident, the impact would be on the reactivity of the cask by analyzing a gradual increase in water level in the spent fuel casks. In addition, the way the keff of the system responds to such an increase is discussed. The paper also provides the results of an assessment of the reactivity effect of water ingress via various pathways/channels.

Research paper thumbnail of Prediction of dose rates around the interim spent fuel storage facility

Radiation Physics and Chemistry, 2020

This paper presents the results of radiation shielding analyses performed for siting of the Inter... more This paper presents the results of radiation shielding analyses performed for siting of the Interim Spent Fuel Storage Facility (ISFSF) with a view of determining what the radiation levels will be around the ISFSF when it is made up of a certain number of casks of a specific design ( Radulescu et al., 2018 ) ( Radiation Shielding Analy, 2004 ). It will also determine the equivalent neutron energy where each cell damage scenarios occurs as a result ionisation.

Research paper thumbnail of Investigation of the release of gaseous fission products from pebble bed molecular reactor's triso coated fuel particle during the HFR-K5 fuel irradiation test

Research paper thumbnail of Criticality safety analysis of the design of spent fuel cask, its manipulation and placement in a long-term storage

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fu... more A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2015

Research paper thumbnail of Ranking of Aluminium Composite Materials for Use as Neutron Absorber Inserts in Spent Fuel Pools

A number of spent fuel pools at nuclear power stations that have been operating since the mid 198... more A number of spent fuel pools at nuclear power stations that have been operating since the mid 1980s or earlier are gradually approaching their full capacity. This puts pressure on the nuclear facility to develop strategies to increase the storage space of the spent fuel pool if untimely shut down is to be avoided. One of the methods that can be employed is to insert neutron-absorbing materials in the spent fuel pool with a view to reducing the number of thermal neutrons which cause fission. This will subsequently reduce the k eff of the system and permit a higher fuel storage density. This paper evaluates the suitability of the material used as neutron absorber inserts (or absorber inserts for short) and ranks several aluminium composite materials for use as absorber inserts on the basis of their effectiveness in decreasing the k eff of the system, thereby recovering some of the storage space consumed as a result of over-conservatism.

Research paper thumbnail of The Effects of Storage Patterns on the Neutron Multiplication Factor of Spent Nuclear Fuel Casks

The type of an array selected for the storage of fissile material such as fuel assemblies or spen... more The type of an array selected for the storage of fissile material such as fuel assemblies or spent fuel casks has a profound effect on the neutron multiplication factor (k eff ) of the system. Given a particular initial enrichment, the neutron multiplication factor of the system can either increase or decrease depending on either the type of the array used (which may either be an n x n , or n x m where n m ), the distance among various fissile units or the total number of units. This paper will present the effects of changes in distances between spent fuel casks in various storage arrays using fresh fuel assumptions.

Research paper thumbnail of Effects of the Location of a Misloaded Fuel Assembly on the Neutron Multiplication Factor of CASTOR X/28 F Spent Fuel Cask

Fuel assembly misload incidents represent a serious nuclear safety concern from a nuclear critica... more Fuel assembly misload incidents represent a serious nuclear safety concern from a nuclear criticality safety point of view, since they can potentially cause reactivity induced accidents (RIA) accidents with severe consequences. Misloads are a result of inadequate spent fuel management such as poor record keeping of important data of the spent fuel (e.g. the exact location of each fuel assembly in the spent fuel pool, the cooling period and burnup) which are crucial for decision whether they will be acceptable for cask loading or not. The cask under study is CASTOR X/28 F which is designed for fuel assemblies with a 10-year cooling period and the average enrichment of 3.25 wt%.

Research paper thumbnail of Sensitivity analysis of parameters important to nuclear criticality safety of Castor X/28F spent nuclear fuel cask

Kerntechnik, 2015

In nuclear criticality safety analysis it is essential to ascertain how various components of the... more In nuclear criticality safety analysis it is essential to ascertain how various components of the nuclear system will perform under certain conditions they may be subjected to, particularly if the components of the system are likely to be affected by environmental factors such as temperature, radiation or material composition. It is therefore prudent that a sensitivity analysis is performed to determine and quantify the response of the output to variation in any of the input parameters. In a fissile system, the output parameter of importance is the keff. Therefore, in attempting to prevent reactivity-induced accidents, it is important for the criticality safety analyst to have a quantified degree of response for the neutron multiplication factor to perturbation in a given input parameter. This article will present the results of the perturbation of the parameters that are important to nuclear criticality safety analysis and their respective correlation equations for deriving the sen...

Research paper thumbnail of Time-dependent variations in the radiological health impact of an interim spent fuel storage facility

Radiation Physics and Chemistry

Research paper thumbnail of Establishing an Effective Nuclear Regulatory Regime: A Case Study of South Africa

Science, Technology & Public Policy

Research paper thumbnail of The Effects of Storage Patterns on the Neutron Multiplication Factor of Spent Nuclear Fuel Casks

International Nuclear Safety Journal, Nov 19, 2012

The type of an array selected for the storage of fissile material such as fuel assemblies or spen... more The type of an array selected for the storage of fissile material such as fuel assemblies or spent fuel casks has a profound effect on the neutron multiplication factor (keff) of the system. Given a particular initial enrichment, the neutron multiplication factor of the system can either increase or decrease depending on either the type of the array used (which may either be an n x n, or n x m where nm), the distance among various fissile units or the total number of units. This paper will present the effects of changes in distances between spent fuel casks in various storage arrays using fresh fuel assumptions.

Research paper thumbnail of Preferential Water Ingress into a Dry Spent Fuel Cask

Journal of Nuclear Energy Science & Power Generation Technology

Research paper thumbnail of Preferential Water Ingress into a Dry Spent Fuel Cask

Journal of Nuclear Energy Science & Power Generation Technology