agr reactor safety

These cores consist of about 3,100 graphite barrels stacked ~10 m high by ~10 m wide and ~10 m long. They have been the backbone of the UK's nuclear generation fleet since the 1980s. generation of AGR type of reactor with improved safety features. Quintessa are using COMSOL Multiphysics ® to construct a diverse assessment of the reactor brick evolution, largely independent of its own internal modelling approach, which can be used to predict the evolution of the shape of the bricks and the rate at which keyway root cracking will occur. Control of reactor operation within limits predicted to be acceptable to the fuel. The approach combines statistical models of the main model inputs, a nonlinear coupled mechanical model of the graphite, and the Monte Carlo approach to determine the cracking rates. CHANSELA is able to suggest the combination of channels that will provide the most useful information subject to user-specified constraints, and to compare this with user-defined selections. Continuing design development of fuel components. The Torness AGR plant on the Lothian coastline of Scotland, 60 km east of Edinburgh, has been chosen as the reference plant and is described in some detail. As of 22 May 2010 , there are seven nuclear generating stations each with two operating AGRs in the United Kingdom, owned and operated by EDF Energy: AGR Fuel Irradiation Performance German fuel has historically demonstrated ~1,000 times better performance than U.S. fuel. Potential failure modes mostly relate to overloading or deterioration of the tensioning system or severe local stressing due to thermal effects. Other custom tools developed for EDF Energy include ASPECT, used to visualise and interpret information collected from eddy current scanning of the graphite core, and LoTAS, a web-based application used for managing and analysing data recorded as fuel is moved in the reactor. Failure of a man-access penetration. In an advanced gas-cooled (AGR) station a controlled chain reaction generates heat which turns water into steam. Low stress levels and in-service inspection facilities ensure that defects in weld or parent metal will not grow undetected during reactor life to critical lengths. These are the second generation of British gas-cooled reactors, using graphite as the neutron moderator and carbon dioxide as coolant. Running The design is such as to make instability failures, for example, weld buckling, impossible. The last of the UK Magnox reactors was completed in 1971 and in the UK was superseded by the Advanced Gas-Cooled Reactor (AGR). A method to assess the performance of AGR vented containment systems S. J. GrahamPerformance Analyst , G. HulmeSenior Performance Analyst , and R. P. HornbyGroup Head NNC Ltd 240 245 Introduction Discussion Acknowledgements To show that a dropped assembly incident would not lead to a situation where radiological targets set in AGR Design Safety Guidelines would be exceeded, the … Physical Integrity of AGR Graphite Cores. Credible failures must not cause sufficient movement of the dome to prevent control rod entry. This safety case shows the reactor can operate and shutdown in all circumstances. LoTAS: Load Trace Analysis Software developed for EDF Energy, Quintessa Supports EDF Energy in Nuclear Reactor Safety, Quintessa becomes a COMSOL Certified Consultant, Quintessa Supports EDF Energy Safety Assessments, Portfolio Selection Tool for AGR Channel Inspections. Advanced Gas-Cooled Reactor (AGR) This is the type of reactor operated by British Energy and is unique to the UK. The QuinStats software was developed in order to fit such statistical models and calculate predictions including variability and uncertainty. FuelThe fuel constitutes the principal source of radioactivity in the reactor and as such presents the main potential hazard of radioactivity. Component The result is that any incidence of high loading leading component failure does not result in gross channel distortion or failure of surrounding components. Provision of an environment compatible with coolant corrosion, deposition, flow-induced vibration and acoustic fields. Reactor Core Design Features and Safety Provisions. Quintessa Supports EDF Energy in Nuclear Reactor Safety. Development of fuel pin coatings to reduce oxide spalling. The baffle material properties are such that any initial defect escaping inspection during manufacture will not grow to critical size during reactor life or before it is detected (unless shown to be inconsequential). AGR-2. Provision of environmental conditions for the fuel stringer tie bar compatible with coolant temperature and corrosion, flow-induced vibration and acoustic fields. Table 1: Failure modes and design safeguards of nuclear fuel. The software employs some novel concepts, including a genetic algorithm for optimising channel selections, and allows every stage of the process to be documented, providing a clear and transparent audit trail. Table 3: Failure modes and design safeguards of the diagrid, gas baffle and restraint tank. We plan to operate the reactor for six months before carrying out further inspections and, subject to regulatory approval, a … Portfolio Selection Tool for AGR Channel Inspections. Provision of a compatible in-reactor fuel route geometry and gas flow conditions. Better fuel performance. “I commend this report and encourage councillors and those interested in the future of the remaining AGR reactors to read it. Tests are also conducted to determine the ultimate capacity of restrain system components. Supporting Reactor Inspections with Data Visualisation. View our energy mix.. We are building a new nuclear power station at Hinkley Point and are planning a second at Sizewell.. Find out which reactors at our eight nuclear power stations are in service and what they are generating (updated on weekdays). Poorer fuel performance. We plan to operate the reactor for six months before carrying out further inspections and, subject to regulatory approval, a … Plot of Kr-85m release -to-birth ratio for various fuel types. The AGR was developed from the Magnox reactor. These various reactor types will now be described, together with current An Advanced Gas-cooled Reactor (AGR) is a type of nuclear reactor designed and operated in the United Kingdom. Data on the other 6 stations are given only … We build and run wind farms across the UK, and we run a large fleet of low carbon nuclear power stations and a smaller fleet of coal and gas stations. The connections that are capable of transferring shear loading between beams and still allowing circumferential movement and a limited amount of rotation. The Reactor At the heart of the reactor is a graphite core called the moderator. Provision of a compatible in-reactor fuel route geometry and gas flow conditions. Plot of Kr-85m release -to-birth ratio for various fuel types. Credible failures of weld or parent material must not exceed sub-critical defects. The design is such as to make instability failures, for example, weld buckling, impossible. This type of reactor is operational only in Great Britain. With specific designs, each type of reactor also has particular operating characteristics. These methods are applied to each of the reactors when they are shut down for routine outages. The integrity of the restraint cylinder connections to the core restraint system and the gas baffle will ensure that significant disturbance of the fuel and control rod channel alignment will not occur. The design of the reactor core complies with the general geometrical and physical requirements of the core as a moderator and a structure. Diagrid AGR power station at Torness. They have been the backbone of the UK's nuclear generation fleet since the 1980s. This includes a 1 in 10,000 year earthquake, larger than the UK as ever experienced. This is called keyway root-cracking which arises in the graphite moderator cores of the reactors. Please enable java script and try again to get complete user experience. Two of them, at Dungeness B on the south-east coast of England, have been undergoing repairs since 2018 – this time because of corrosion of vital pipework – although cracks in the graphite blocks are also a safety issue here too. The structures mentioned above are key components to the reactor coolant circuit, the purpose being to determine the flow path of the coolant through the moderator and fuel channels. Post Irradiation Examination (PIE) of components. This is provided in accordance with the maximum allowable clearance required for channel straightness and the minimum clearance dictated by graphite distortion. Over the past 15 years, Quintessa has carried out research and development in support of EDF Energy (and formerly British Energy) for the continued safe operation of Advanced Gas Cooled Reactors (AGRs). Nuclear Power-> Nuclear Power Plant-> Types of Reactors-> Advanced Gas-cooled Reactor. The presence of seals reduces the increase in coolant flow into an empty channel that normally occurs and this guards against flow starvation into neighboring channels. Continued operation of Advanced Gas cooled Reactors. Provision of adequate cooling under normal and fault conditions. When the reaction becomes self-sustaining, the reactor is said to be ‘critical’. The graphite brick and key geometry is optimized to give the best possible component and interconnecting strength, which is derived from tests conducted on slices of graphite bricks. The fundamental nuclear safety requirements of the AGR cores are to allow unimpeded movement of control rods and fuel, and to secure adequate cooling of the fuel and core structure, both in normal and fault /hazard conditions. Credible failures must not cause movement of the circulator casings that are connected to the baffle skirt. Credible failures must not cause sufficient movement of the dome to prevent control rod entry. As the name suggests, it is an advance on the earlier UK Magnox design. Failure Modes and Design Safeguards Quintessa has developed a custom software tool, CHANSELA, which is used to visualise information on the reactor cores and to support decisions on which fuel channels should be inspected to support continued safe operation. To ensure that the release of activity from the fuel pins is strictly limited, it is essential that all the fuel components are of high integrity under all operating and fault conditions. The models employed are based on physical understanding of the key processes taking place and have been shown to have good predictive power by comparing model predictions made before samples are taken from the reactor with measurements made at inspection outages. Pressure induced loads in graphite columns, keys and the restraint system; Instability loading generated by brick bowing resulting from irradiation induced distortion; Vibration loading, including seismic loading; Self weights and dropped channel components; Any other interacting loads from in-channel components; Transient loads arising from differential response to power changes or faults; Irradiation induced stresses in the graphite; Thermal stresses in restraint and support structures. The graphite core of the AGR design has the potential to be the life-limiting component. 12 Jan 2012. Keyway clearances are kept to a minimum to prevent brick-to-brick jamming and to reduce cumulative core moments. ABOUT AGR Local experts, global supply We bring quality, reliability and experience to Sodium Cyanide manufacture and supply. EDF Energy currently owns and operates 8 nuclear power plants in the UK. The structural redundancy of the diagrid ensures that significant disruption of the reactor core is not possible as a result of a credible growth of defects in structural welds or parent material. Serious breach of the structure could cause a reduction in coolant flow over the fuel, which in turn, could lead to fuel failures. ; As the reactors age some of the graphite is oxidised, resulting in increased porosity and lower density. The growth rate of possible defects will be low and observable by in-service inspection by remote TV cameras. 6 Jul 2005 HOW AGR CORE MODELLING SUPPORTS REACTOR SAFETY CASES Tom Bush 1 1 Senior Structural Analyst, AMEC Foster Wheeler, UK ABSTRACT EDF Energy can only operate an Advanced Gas-cooled Reactor (AGR) if the safety of operation is demonstrated by a safety case. From the viewpoint of distortion, the keying length in the nine middle layers extends over approximately one third of each layer, while in the top and bottom layers, this length can be increased: it is in these two layers that the maximum loads are transmitted. Credible failures of weld or parent material must not exceed sub-critical defects. reactors such as AGR. A further reactor type, the so-called fast reactor, has been developed to full-scale demonstration stage. These assessments are used by EDF as evidence in their safety cases, demonstrating that the control rods can always be used to shut down and hold down a reactor, even during a one-in-10,000-year earthquake. An overview of the design and characteristics of the Advanced Gas Cooled Reactor (AGR) is given. committed to the receipt of spent Advanced Gas-cooled Reactor (AGR) fuel from Électricité de France Energy Nuclear Generation Ltd (EdF) which would have previously been reprocessed but from December 2018 will be interim stored until final disposal. The Yongbyon reactor, which refer to the Calder Design of a pin structure to withstand pressure differentials and temperature transients associated with credible reactor faults. Six types of reactor (Magnox, AGR, PWR, BWR, CANDU and RBMK) have emerged as the designs used to produce commercial electricity around the world. Failure Modes Today, in-reactor AGR TRISO fuel performance is as good as German fuel at twice the burnup. The graphite core of these reactors cannot be replaced and ageing mechanisms such as weight loss and cracking can change the mass, dimensions and material properties within the core. The graphite core of the AGR design has the potential to be the life-limiting component. The graphite brick and key geometry is optimized to give the best possible component and interconnecting strength, which is derived from tests conducted on slices of graphite bricks. The Torness AGR plant on the Lothian coastline of Scotland, 60 km east of Edinburgh, has been chosen as the reference plant and is described in some detail. Design development of lifting, supporting and handling components and the development of handling techniques. It looks like your browser does not have JavaScript enabled. ... breaches of safety procedures, which led to the steam explosion at Chernobyl in 1986. A critical part of the AGR safety case is demonstrating the continued physical integrity of the graphite cores that are made up of a large number of bricks. An advanced gas-cooled reactor (AGR) is a British design of nuclear reactor.AGRs are using graphite as the neutron moderator and carbon dioxide as coolant. The reasons for the development of this reactor type were part political (development of a domestic technology) and part technical, in particular the increased thermodynamic efficiency associated with the much higher coolant temperatures of the AGR … The main problem is a serious generic fault in AGR reactors. As such, they pose unique challenges to the operator, EDF Energy and to us as the regulator. Within the interconnecting restraint beams connections between adjacent restraint beams provide a high degree of redundancy in the restraint system. Over the past 15 years, Quintessa has carried out research and development in support of EDF Energy (and formerly British Energy) for the continued safe operation of Advanced Gas Cooled Reactors (AGRs). On current plans, 7 of those stations - the Advanced Gas-Cooled Reactor stations (AGRs) - … generation of AGR type of reactor with improved safety features. The steam then powers turbines which, in turn, drive the electrical generators. 2. As such that are a number of safety related objectives pursued at the design stage of the reactor together with measures to secure them. Poorer fuel performance. Advanced statistical methods have been used to enable the safe period of reactor operation to be calculated on the basis of the history of brick defects observed to date, and to determine the optimum future inspection strategy. Reactor Core Inspections _ Channel Bore Measurement Unit (CBMU). We value service, long-term relationships and contributing to the success of our customers with an uncompromising focus on people, safety and the environment. Credible failures must not cause disruption of the boilers (which the baffle supports). Reactor Core Design Features and Safety Provisions The design of the reactor core complies with the general geometrical and physical requirements of the core as a moderator and a structure. Currently, six of these 12 AGR reactors are turned off, out of service for maintenance or safety checks. These are the second generation of British gas-cooled reactors, using graphite as the neutron moderator and carbon dioxide as coolant. 11 Jan 2016. Better fuel performance. Poorer fuel performance. Provision of an environment compatible with coolant corrosion, deposition, flow-induced vibration and acoustic fields. The Boilers “We seismically assess each of the UK’s AGR reactor cores. The Redundancy within the core structure is provided by horizontally by the inter-brick keying system and vertically by the inter-brick shear connections. Safety tests were conducted on fourteen fuel compacts from AGR-1, the first irradiation experiment of the Advanced Gas Reactor (AGR) Fuel Development and Qualification program, at temperatures ranging from 1600 to 1800°C to determine fission product release at temperatures that bound reactor … Quintessa provides support in a number of key areas associated with the evolution of the reactor cores as they age, and predictions of the evolution of graphite properties with time. This safety case shows the reactor can operate and shutdown in all circumstances. - There are seven AGR Stations with 14 reactors • The early AGRs have had significant safety upgrades to meet modern standards - But even the Sizewell B basic (USA) design had to be upgraded to meet modern UK standards The AGR is a higher temperature reactor than the PWR with higher thermal efficiency Better fuel performance. Low stress levels and in-service inspection facilities ensure that defects in weld or parent metal will not grow undetected during reactor life to critical lengths. Radioactive contamination of the gas circuit due to spalled oxide. An Advanced Gas-cooled Reactor (AGR) is a type of nuclear reactor designed and operated in the United Kingdom. It would be possible simply to use the 'best' model, but it is better to work with several models that are consistent with the data but which may give different forecasts of future core behaviour, enabling uncertainties to be quantified. failure or a need to shut the reactor down, gravity makes these rods drop fully into the core, shutting down the reactor. This safety evaluation will help accelerate licensing of advanced high-temperature reactor designs, by obtaining NRC review and approval of key AGR program data demonstrating TRISO fuel particle performance under high-temperature reactor conditions. Design development of lifting, supporting and handling components and the development of handling techniques. SAFETY & COMPLIANCE Our uncompromising focus on safety. Today, in-reactor AGR TRISO fuel performance is as good as German fuel at twice the burnup. Currently, 14 AGR's are in operation at 6 different sites. The user experience is limited because of Java Script of your browser is disabled. The baffle material properties are such that any initial defect escaping inspection during manufacture will not grow to critical size during reactor life or before it is detected (unless shown to be inconsequential). Currently six of these 12 AGR reactors are turned off – out of service for maintenance or safety checks. Credible failures must not cause movement of the circulator casings that are connected to the baffle skirt. Like with Hunterston, it also appears prudent for public safety reasons to consider the early closure of the Hinkley Point B site given a similar age and an increasing level of keyway route cracks in the graphite bricks. Magnox reactors were also graphite moderated and CO 2 cooled, used natural uranium fuel in metal form, and water as secondary coolant. The thick bioshield above the reactor vessel and the design of the control ... • System used for AGR -1 safety testing campaign; AGR -2 and AGR -3/4 safety tests in progress . Statistical modelling methods are also used to model the evolution of graphite properties including weight loss. HOW AGR CORE MODELLING SUPPORTS REACTOR SAFETY CASES Tom Bush 1 1 Senior Structural Analyst, AMEC Foster Wheeler, UK ABSTRACT EDF Energy can only operate an Advanced Gas-cooled Reactor (AGR) if the safety of operation is demonstrated by a safety case. Incorporation of central hoists inertial collectors to collect active dust. It is a requirement of the nuclear site licence for the licensee to determine and justify the operating limits of its nuclear plant. Credible failures must not cause disruption of the boilers (which the baffle supports). • TRISO and SiC failure fractions during irradiation and during safety testing are well below applicable reactor design specifications • Our understanding of fission product behavior in TRISO fuel and coating evolution during irradiation has been greatly advanced by the AGR-1 … AGR Fuel Irradiation Performance German fuel has historically demonstrated ~1,000 times better performance than U.S. fuel. Hunterston B nuclear power plant (Image: EDF) Dungeness Reactor 22 and Reactor 21 were taken offline, respectively, on 27 August and 19 September, 2018 - for pre-planned outages. The graphite irradiations in the High Flux Reactor (HFR) mimic and accelerate the aging mechanisms that take place in an AGR. 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