AGRs were developed from the Magnox type reactor.These are the second generation of British gas-cooled reactors. This safety case shows the reactor can operate and shutdown in all circumstances. 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 sources of stresses on the reactor core have been identified as the following: There are significant safety provisions incorporated into the design of the reactor core to address the above stresses. They have been the backbone of the UK's nuclear generation fleet since the 1980s. Failure modes and design safeguards of the diagrid, gas baffle and restraint tank. The 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. Credible failures must not cause sufficient movement of the dome to prevent control rod entry. AGR Fuel Irradiation Performance German fuel has historically demonstrated ~1,000 times better performance than U.S. fuel. The AGR was developed from the Magnox reactor. AGR-2. 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 … 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. 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. An overview of the design and characteristics of the Advanced Gas Cooled Reactor (AGR) is given. The design is such as to make instability failures, for example, weld buckling, impossible. Credible failures of weld or parent material must not exceed sub-critical defects. 20 Jan 2010. Portfolio Selection Tool for AGR Channel Inspections. 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. Poorer fuel performance. Data on the other 6 stations are given only … Restraint Tank Better fuel performance. “I commend this report and encourage councillors and those interested in the future of the remaining AGR reactors to read it. 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. Magnox reactors were also graphite moderated and CO 2 cooled, used natural uranium fuel in metal form, and water as secondary coolant. Measurements of the channel gas outlet temperature, fission product level in the coolant and coolant composition are used to assess and, if necessary, to control stringer performance and integrity. Since the Yongbyon reactor is a Magnox type GCR, the operating principle is the same, but the electrical power is different, so there is a difference in the amount of nuclear fuel to be loaded and so is the moderator. The reactor core is a sixteen sided stack of interconnected graphite bricks maintained in position by a steel restraint structure surrounding the core, and is supported by a system of steel plates known as the diagrid. Quintessa Supports EDF Energy in Nuclear Reactor Safety. 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. Poorer fuel performance. 6 Jul 2005 Failure Modes 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. This is provided in accordance with the maximum allowable clearance required for channel straightness and the minimum clearance dictated by graphite distortion. EDF Energy currently owns and operates 8 nuclear power plants in the UK. ; As the reactors age some of the graphite is oxidised, resulting in increased porosity and lower density. ... breaches of safety procedures, which led to the steam explosion at Chernobyl in 1986. It is a requirement of the nuclear site licence for the licensee to determine and justify the operating limits of its nuclear plant. Design Safeguards The fuel constitutes the principal source of radioactivity in the reactor and as such presents the main potential hazard of radioactivity. 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 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 … Today, in-reactor AGR TRISO fuel performance is as good as German fuel at twice the burnup. Please enable java script and try again to get complete user experience. Continuing design development of fuel components. These various reactor types will now be described, together with current The Yongbyon reactor, which refer to the Calder Provision of adequate cooling under normal and fault conditions. 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. Supporting Reactor Inspections with Data Visualisation. The QuinStats software was developed in order to fit such statistical models and calculate predictions including variability and uncertainty. As the name suggests, it is an advance on the earlier UK Magnox design. Tests are also conducted to determine the ultimate capacity of restrain system components. We plan to operate the reactor for six months before carrying out further inspections and, subject to regulatory approval, a … The UK's last Magnox reactor closed at the end of 2015. 2. Better fuel performance. This includes a 1 in 10,000 year earthquake, larger than the UK as ever experienced. Development of fuel pin coatings to reduce oxide spalling. We plan to operate the reactor for six months before carrying out further inspections and, subject to regulatory approval, a … Credible failures must not cause movement of the circulator casings that are connected to the baffle skirt. 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 . FuelThe fuel constitutes the principal source of radioactivity in the reactor and as such presents the main potential hazard of radioactivity. Design development of lifting, supporting and handling components and the development of handling techniques. 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. 12 Jan 2012. Currently, six of these 12 AGR reactors are turned off, out of service for maintenance or safety checks. generation of AGR type of reactor with improved safety features. 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: Each station employs twin reactors. 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. An Advanced Gas-cooled Reactor (AGR) is a type of nuclear reactor designed and operated in the United Kingdom. Today, in-reactor AGR TRISO fuel performance is as good as German fuel at twice the burnup. As such that are a number of safety related objectives pursued at the design stage of the reactor together with measures to secure them. 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. PIE of the AGR … 11 Jan 2016. 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). We are committed to being a safe and responsible manufacturer and global distributor of quality Sodium Cyanide products, ensuring the wellbeing of employees, customers, communities and the environments in which we operate. 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). 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. Pin failure during reactor operation. Reactor Core Inspections _ Channel Bore Measurement Unit (CBMU). 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 … 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. As well as moderation, the fun… ORNL Core Conduction Cooldown Test Facility • Built previously for TRISO particle heating tests and In the event of a Warwick link failure, the loading applied to a beam can be transferred to its immediate neighbour without seriously affecting core behaviour. This is called keyway root-cracking which arises in the graphite moderator cores of the reactors. Redundancy within the core structure is provided by horizontally by the inter-brick keying system and vertically by the inter-brick shear connections. The graphite irradiations in the High Flux Reactor (HFR) mimic and accelerate the aging mechanisms that take place in an AGR. The steam then powers turbines which, in turn, drive the electrical generators. Potential failure modes are listed in the table below, together with brief comments on the design and operational features provided to afford protection against them. EDF Energy currently owns and operates 8 nuclear power plants in the UK. These methods are applied to each of the reactors when they are shut down for routine outages. 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. Provision of a compatible in-reactor fuel route geometry and gas flow conditions. Statistical modelling methods are also used to model the evolution of graphite properties including weight loss. The connections that are capable of transferring shear loading between beams and still allowing circumferential movement and a limited amount of rotation. These cores consist of about 3,100 graphite barrels stacked ~10 m high by ~10 m wide and ~10 m long. 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. 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. Potential failure modes mostly relate to overloading or deterioration of the tensioning system or severe local stressing due to thermal effects. It looks like your browser does not have JavaScript enabled. AGR Fuel Irradiation Performance German fuel has historically demonstrated ~1,000 times better performance than U.S. fuel. 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. Design of a pin structure to withstand pressure differentials and temperature transients associated with credible reactor faults. Hunterston B nuclear power station is a nuclear power station in North Ayrshire, Scotland.It is located about 6 miles (9 km) south of Largs and about 2.5 miles (4 km) north-west of West Kilbride on the Firth of Clyde coast. 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. Plot of Kr-85m release -to-birth ratio for various fuel types. Credible failures must not cause sufficient movement of the dome to prevent control rod entry. The restarts of three advanced gas-cooled reactor (AGR) units at EDF's Dungeness B and Hunterston B nuclear power plants in the UK have been postponed. When they are partially raised, the neutrons become free to cause `fission’ in the uranium atoms and release more neutrons. These are the second generation of British gas-cooled reactors, using graphite as the neutron moderator and carbon dioxide as coolant. Looked at functionally, the three basic safety functions in a nuclear reactor are: to control reactivity, to cool the fuel and; to contain radioactive substances. Safety Requirements of an Advanced Gas Reactor, 1. Credible failures must not cause disruption of the boilers (which the baffle supports). 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. 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