The resistance to impact of spent Magnox fuel transport flasks

International Nuclear Information System (INIS)

Anon.

1985-01-01

This book completes the papers of the four-year programme of research and demonstrations embarked upon by the CEGB in 1981, culminating in the spectacular train crash at Old Dalby in July 1984. It explains the CEGB's operations in relation to the transportation of spent Magnox fuel. The public tests described in this book are more effective in improving public understanding and confidence than any amount of explanations could have been, raising the wider question of how best the scientific community can respond to the legitimate concerns of the man and woman in the street about the generating of electricity from nuclear power. The contents are: Taking care; irradiated fuel transport in the UK; programming for flask safety; the use of scale models in impact testing; flask analytical studies; drop test facilities; demonstration drop test; a study of flask transport impact hazards; impact of Magnox irradiated fuel transport flasks into rock and concrete; rail crash demonstration scenarios; horizontal impact testing of quarter scale flasks using masonry targets; horizontal crash testing and analysis of model flatrols; flatrol test; analysis of full scale impact into an abutment; analysis of primary impact forces in the train crash demonstration; horizontal impact tests of quarter scale Magnox flasks and stylised model locomotives; predictive estimates for behaviour in the train crash demonstration; design and organization of the crash; execution of the crash demonstration by British Rail; instrumentation for the train crash demonstration; photography for the crash demonstration; a summary of the CEGB's flask accident impact studies

Radiological characterisation experience with Magnox reactors

International Nuclear Information System (INIS)

Westall, Bill A.; Towton, Barbara

2012-01-01

At the end of generation, power reactors will be decommissioned. Whether decommissioning is prompt or deferred, knowledge of the radioactive inventory of plant and structures is needed to develop and underpin the decommissioning strategy. As decommissioning progresses the level of detail required for the radioactive inventory increases as more specific and detailed questions need answering. Failure to adequately characterise will result in increased costs and project overruns due to missing optimal solutions, over pessimistic assumptions or unforeseen problems and regulatory issues. Radiological characterisation for decommissioning of Magnox power stations in the UK has been in progress for over a quarter of a century. Firstly measurements and calculations were carried out to develop a strategy. These have been followed by measurements to determine radioactive inventories of waste streams and packages or to allow decontamination of structures and most recently for partial de-licensing of sites. Some examples of the work carried out for the Magnox stations will be given, ranging from the neutron activation calculations to estimate the radioactive inventory within a bio-shield and measurements to validate them. Various plant and structures where the radioactive inventory is due to contamination have been characterised by measurements and examples for boilers and cooling ponds will be discussed. Various routine and ad-hoc measurements and shielding assessments have been performed on waste forms to help satisfy conditions for acceptance for disposal or exemption, which will be reviewed. Finally the measurements for de-licensing and the successful application of Data Quality Objectives will be addressed. (authors)

Upgrading of fire protection arrangements at Magnox power stations in the United Kingdom

International Nuclear Information System (INIS)

Zhu, L.H.

1998-01-01

The methodology used in conducting fire hazard assessments at Magnox Reactor power stations operated by Magnox Electric plc is described. The assessments use a deterministic approach. This includes the identification of essential plant and the associated supporting systems required for the safe trip, shutdown and post-trip cooling of the reactor, assessment of the location of the essential plant and the vulnerability of these plant in the presence of a fire, assessment of essential functions against the effects of a fire and identification of improvements to the fire protection arrangements. Practical aspects of fire protection engineering on operating power stations are discussed and examples of improvements in protection described. (author)

Optimising end of generation of Magnox reactors

International Nuclear Information System (INIS)

Hall, D.; Hopper, E.D.A.

2014-01-01

Designing, justifying and gaining regulatory approval for optimised, terminal fuel cycles for the last 4 of the 13 strong Magnox Fleet is described, covering: - constraints set by the plant owner's integrated closure plan, opportunities for innovative fuel cycles while preserving flexibility to respond to business changes; - methods of collectively determining best options for each site; - selected strategies including lower fuel element retention and inter-reactor transfer of fuel; - the required work scope, its technical, safety case and resource challenges and how they were met; - achieving additional electricity generation worth in excess of Pound 1 b from 4 sites (a total of 8 reactors); - the keys to success. (authors)

Nuclear Electric: the misuse of the subsidy and the case for the immediate closure of Magnox

International Nuclear Information System (INIS)

1992-11-01

The nature and purpose of fossil fuel levy which creates a subsidy for the nuclear industry is discussed. It is claimed that without the subsidy the operation of Magnox and AGR stations generates electricity at a loss. This means that most of the fossil fuel levy is being used to make up Nuclear Electric's losses. The rest is mostly being used to build the Sizewell-B power plant. This is in contrast to the popular belief and understanding that the subsidy is for decommissioning old plants, and cleaning up accumulated spent fuels and other wastes. The economics of the Magnox stations are discussed and Nuclear Electric's claim that closing them would not stop the losses is challenged. (U.K.)

Radiocarbon Mass Balance for a Magnox Nuclear Power Station

International Nuclear Information System (INIS)

Metcalfe, M.P.; Mills, R.W.

2016-01-01

Nuclear power generation in the United Kingdom is based principally on graphite-moderated gas-cooled reactors. The mass of irradiated graphite associated with these reactors, including material from associated experimental, prototype and production reactors, exceeds 96,000 tonnes. One of the principal long-lived radionuclides produced during graphite irradiation is radiocarbon (C-14), which has a half-life of 5730 ± 40 years. Decommissioning and graphite waste management strategies must take account of this radionuclide. In order to identify appropriate options for addressing the potential hazard of C-14, it is important that the production processes are understood and the distributions and concentrations of C-14 are characterised. In fact, C-14 precursors and their activation processes are well-known. However, there is ongoing debate over the relative importance of different C-14 precursors, which will determine the location of C-14 within graphite components and hence its mobility/response to treatment. A generally held misconception concerning C-14 in irradiated graphite is that generic statements can be made about its precursors and their location. C-14 location and activities will depend upon the composition of the original manufactured graphite (raw materials, impurities), the chemical environment of the graphite during service and the irradiation history of the graphite. So, while there may be some similarities across, for example, carbon dioxide cooled graphite moderated designs (Magnox, AGR, UNGG), any informed assessment of a core’s C-14 inventory would require more-precise characterisation. The analysis presented here focuses on a UK Magnox reactor core, Reactor 1 at Wylfa Nuclear Power Station. The objective of the analysis is to present a full C-14 mass balance over a selected period of operation for which there are accurate C-14 discharge records. The analysis presented here provides the first assessment of the principal C-14 activation pathways

Analysis of irradiated Magnox fuel for fission product and actinide elements

International Nuclear Information System (INIS)

Foster, E.; Fudge, A.J.; Glover, K.M.; Wiltshire, R.A.P.

1980-03-01

This report describes the methods used for, and the results obtained from, chemical and isotopic analysis of four Magnox fuel samples of known irradiation history. The analysis of this material was carried out in conjunction with CEGB, Berkeley Nuclear Laboratories and BNFL. The data obtained was used to evaluate the accuracy of fuel composition as predicted by computer codes such as RICE (Reactor Inventory Code). (author)

Applications of virtual reality in Magnox

International Nuclear Information System (INIS)

Smith, A.L.

2000-01-01

This paper describes the current state of use of VR-based simulation tools to assist the design, development and implementation of a range of complex projects within BNFL Magnox Generation. VR systems are used throughout the life cycle of a project. As a conceptual design tool, parametric techniques have been used to optimize limb lengths of a manipulator used for detailed in-reactor inspection. Extensive path planning is carried out off-line, allowing the rehearsal phase to concentrate on difficult issues such as interactions with the work site. During the rehearsal and site implementation phases, the use of a real-time display of a manipulator working in a simulated reactor environment supplements the views from surveillance cameras. Finally, use of output from the VR system can support the quality assurance and documentation aspects of a task by providing further evidence that the correct components have been inspected/repaired. (author)

Seismic evaluation of non-seismically designed existing Magnox nuclear power plants

International Nuclear Information System (INIS)

Kunar, R.R.

1984-01-01

The philosophy and method adopted for the seismic assessment of three existing Magnox nuclear stations in the United Kingdom are presented in this paper. The plants were not seismically designed. The particular procedures that were applied were tailored to suit the difficulties of lack of data which is somewhat inevitable for plants designed and built about 25 to 30 years ago. Special procedures included on-site testing with a portable shake table, low vibration testing using a structural dynamics analyser, and on-site inspections. The low vibration testing was most invaluable in detecting differences between 'as-built' conditions and the engineering drawings. From the point of view of economics, this was more effective than conducting full structural surveys to determine the as-built conditions. The testing results also provided confidence in the answers from numerical models. The philosophy adopted for the Magnox reactors in the seismic assessment was to determine what peak ground accelerations the sites can sustain and then evaluate the chances of exceeding the ground accelerations over the remaining lifetime of the plants. The peak ground acceleration for each site was determined on the basis of the criteria of safe shutdown and prevention of significant off-site radiological exposure

Magnox Electric Littlebrook reactor inspection and repair rehearsal facility

International Nuclear Information System (INIS)

Barnes, S.A.; Clayton, R.; Gaydon, B.G.; Ramsey, B.H.

1996-01-01

Magnox reactors, although designed to be maintenance free during their operational life, have nevertheless highlighted the need for test rig facilities to train operators in the methods and techniques of reactor inspection and repair. The history of the facility for reactor engineering development (FRED) is described and its present role as a repair rehearsal facility noted. Advances in computer graphics may, in future, mean that such operator training will be virtual reality rather than analog reality based; however the need for such rigs to commission techniques and equipment and to establish performance and reliability is likely to continue. (UK)

Equilibrium leach testing of Magnox swarf and sludge

International Nuclear Information System (INIS)

Amin, A.; Angus, M.J.; Kirkham, I.A.; Tyson, A.

1988-10-01

A static equilibrium leach test has been developed to simulate repository conditions after ground water has penetrated the near field barrier. The repository components - waste, matrix and backfill - have been equilibrated with water for up to one year. Leachates were analysed for U, Pu, Np 237 , Am 241 , Cs 137 , Sr 90 , Tc 99 , I 129 and C 14 . Results are presented for leaching from Magnox fuel cladding wastes using a combination of matrices, backfills and atmospheric conditions. The equilibrium concentrations were generally very low and have been compared with the concentration of each isotope in drinking water that would give an adult an annual effective dose equivalent of 0.1mSv. (author)

Equilibrium leach testing of Magnox swarf and sludge

International Nuclear Information System (INIS)

Amin, A.; Angus, M.J.; Kirkham, I.A.; Tyson, A.

1987-10-01

A static equilibrium leach test has been developed to simulate repository conditions after ground water has penetrated the near field barrier. The repository components - waste, matrix and backfill - have been equilibrated with water for up to one year. Leachates were analysed for U, Pu, Np 237 , Am 241 , Cs 137 , Sr 90 , Tc 99 , I 129 and C 14 . Results are presented for leaching from Magnox fuel cladding wastes using a combination of matrices, backfills and atmospheric conditions. The equilibrium concentrations were generally very low and have been compared with the concentration of each isotope in drinking water that would give an adult an annual effective dose equivalent of 0.1mSv. (author)

Radiocarbon mass balance for a Magnox nuclear power station

International Nuclear Information System (INIS)

Metcalfe, M.P.; Mills, R.W.

2015-01-01

Highlights: • First comprehensive assessment of C-14 arisings in a Magnox nuclear power station. • C-14 production in graphite and coolant gas quantified by activation modelling. • Principal C-14 production pathway is via C-13 with a small contribution from N-14. • C-14 mass balance model provides a basis for analyses on other reactors. - Abstract: Nuclear power generation in the United Kingdom is based principally on graphite-moderated gas-cooled reactors. The mass of irradiated graphite associated with these reactors, including material from associated experimental, prototype and plutonium production reactors, exceeds 96,000 tonnes. One of the principal long-lived radionuclides produced during graphite irradiation is radiocarbon (C-14). Its potential as a hazard must be taken into account in decommissioning and graphite waste management strategies. While C-14 production processes are well-understood, radionuclide distributions and concentrations need to be characterised. A common misconception is that generic statements can be made about C-14 precursors and their location. In fact, the composition of the original manufactured material, the chemical environment of the graphite during service and its irradiation history will all influence C-14 levels. The analysis presented here provides the first assessment of the principal C-14 activation pathways for a UK Magnox reactor. Activation modelling has been used to predict C-14 production rates in both the graphite core and the carbon dioxide coolant over a selected period of operation and the results compared with monitored site C-14 discharges. Principal activation routes have been identified, which should inform future graphite waste management strategies relating to radiocarbon

Magnox Swarf Storage Silo Liquor Effluent Management -Sellafield Site, Cumbria, UK - Legacy radioactive waste storage - 59271

International Nuclear Information System (INIS)

Le Clere, Stephen

2012-01-01

The Sellafield Magnox Swarf Storage Silo (MSSS) was constructed to provide an underwater storage facility for irradiated magnox cladding metal Swarf, as well as miscellaneous beta-gamma waste from several sources. Liquid effluent arisings from hazard reduction activities at this facility represent the toughest effluent treatment challenge within the company's Legacy Ponds and Silos portfolio. The key requirement for hazard reduction has generated many substantial challenges as the facility is readied for decommissioning. This has demanded the production of carefully thought out strategies for managing, and overcoming, the key difficulties to be encountered as hazard reduction progresses. The complexity associated with preparing for waste retrievals from the Magnox Swarf Storage Silo, has also generated the demand for a mix of creativity and perseverance to meet the challenges and make progress. Challenging the status quo and willingness to accept change is not easy and the road to overall hazard reduction for the high hazard MSSS facility will demand the skills and investment of individuals, teams, and entire facility work-forces. The first steps on this road have been taken with the successful introduction of liquor management operations, however much more is yet to be achieved. Clear communication, investing in stakeholder management, perseverance in the face of difficulty and a structured yet flexible programme delivery approach, will ensure the continued success of tackling the complex challenges of treating liquid effluent from a legacy fuel storage silo at the Sellafield Site. (authors)

Interim dry fuel storage for magnox reactors

Energy Technology Data Exchange (ETDEWEB)

Bradley, N [National Nuclear Corporation, Risley, Warrington (United Kingdom); Ealing, C [GEC Energy Systems Ltd, Whetstone, Leicester (United Kingdom)

1985-07-01

In the UK the practice of short term buffer storage in water ponds prior to chemical reprocessing had already been established on the early gas cooled reactors in Calder Hall. Thus the choice of water pond buffer storage for MGR power plants logically followed the national policy decision to reprocess. The majority of the buffer storage period would take place at the reprocessing plant with only a nominal of 100 days targeted at the station. Since Magnox clad fuel is not suitable for long term pond storage, alternative methods of storage on future stations was considered desirable. In addition to safeguards considerations the economic aspects of the fuel cycle has influenced the conclusion that today the purchase of a MGR power plant with dry spent fuel storage and without commitment to reprocess would be a rational decision for a country initiating a nuclear programme. Dry storage requirements are discussed and two designs of dry storage facilities presented together with a fuel preparation facility.

Interim dry fuel storage for magnox reactors

International Nuclear Information System (INIS)

Bradley, N.; Ealing, C.

1985-01-01

In the UK the practice of short term buffer storage in water ponds prior to chemical reprocessing had already been established on the early gas cooled reactors in Calder Hall. Thus the choice of water pond buffer storage for MGR power plants logically followed the national policy decision to reprocess. The majority of the buffer storage period would take place at the reprocessing plant with only a nominal of 100 days targeted at the station. Since Magnox clad fuel is not suitable for long term pond storage, alternative methods of storage on future stations was considered desirable. In addition to safeguards considerations the economic aspects of the fuel cycle has influenced the conclusion that today the purchase of a MGR power plant with dry spent fuel storage and without commitment to reprocess would be a rational decision for a country initiating a nuclear programme. Dry storage requirements are discussed and two designs of dry storage facilities presented together with a fuel preparation facility

An electrochemical study of the effect of nitrate and sulphate on the corrosion behaviour of Magnox AL80 in pond environments

International Nuclear Information System (INIS)

Tyfield, S.P.; Martin, F.

1987-04-01

The open circuit rest potential and the cyclic potentiodynamic polarisation behaviour of abraded Magnox AL80 has been studied at 22 0 C in sodium hydroxide solutions (200 gm -3 , pH ∼ 11.6) dosed separately and with a combination of chloride and nitrate. The results are considered in terms of the effect of the presence of nitrate on the initiation of localised breakdown of the passive film on Magnox AL80. A similar study of the effect of the presence of sulphate in the sodium hydroxide medium (200 gm -3 ) is described and the aggressivity of sulphate is compared to that of chloride. (author)

Recent advances in automated ultrasonic inspection of Magnox power stations

International Nuclear Information System (INIS)

Wooldridge, A.B.

2006-01-01

Magnox Electric operates a number of Magnox nuclear power stations, some of which have presented difficult inspection challenges. This paper will describe recent advances in automated ultrasonic techniques which have enabled additional, fully effective and qualified inspections to be introduced. The examples chosen involve phased array inspection of fillet welds and the introduction of 3D data display and analysis using NDT Workbench. Ultrasonic phased arrays have been optimised for inspection of fillet welded structures where physical access for the operator is very awkward and the surfaces available for probe scanning are very restricted. In addition to controlling the beam direction and focus depth, the systems have also optimised the depth of field by varying the number of phased array elements fired at a given time. These phased array inspections are substantially superior in quality, reliability and speed compared with that achievable by conventional manual inspection. Analysis of automated ultrasonic data can be very time-consuming if defects are complex. NDT Workbench significantly improves data analysis for complex geometries and defects primarily because of the 3D data displays of multiple beams and automated logging of measurements. This system has been used in 2005 for data analysis of complex defects where sizing accuracy was particularly important. Both these inspection procedures have been formally qualified using the ENIQ (European Network for Inspection Qualification) Methodology. Such qualification was achieved more easily because of the rigorous in house training programmes established in each case and because the Technical Justifications referred to evidence from previous related qualifications whenever appropriate. The timely achievement of inspection qualification demonstrates that the new systems have reached sufficient maturity to be used with confidence for high quality inspections. (orig.)

Radiation Protection in the Magnox Ponds Programme, United Kingdom

International Nuclear Information System (INIS)

2015-01-01

The Magnox ponds programme has a different approach to radiation protection. It is now seen as a key part of the delivery side in a project. It is embedded within the project, working permanently alongside the other members of the team. Typically, more resources have been provided to keep up with the changing conditions. The understanding of problems from a radiation protection standpoint is much greater, meaning solutions can be fully considered. Here are two examples of technologies implemented by radiation protection to help aid delivery: (a) Teledosimetry is used in high radiation environments for tasks such as pond floor cleanup. It uses wireless transmitters and receivers to transmit dose information to a remote computer, where it is monitored constantly. This means workers no longer need constant workface monitoring support. They can also focus on the task in hand and not worry about the dose they are accruing. It also reduces the potential for miscommunication between the work party and those monitoring dosages. A single clear instruction (a siren) is given to the workers when they are approaching their dose limit, indicating for them to leave the area. Using teledosimetry reduces total dosage by 33–50% and improves the efficiency of the workforce. (b) Historically, within Magnox, work in high radiation airborne environments would have been conducted in airline suits, owing to limited company tolerance for potential internal doses to the workforce. This method of working has a number of disadvantages such as increased time and cost and additional conventional safety issues. Work in such areas wearing respirators is much more effective, but has the potential to incur internal dosages. This is unlikely if managed properly. The ponds programme uses a method of derived air concentration hours (DACh) tracking to assess potential internal doses. This effectively assigns a potential dose to each worker based on air sample results from their location and

Remote repairs and refurbishment of reactor internal structures of magnox plant

International Nuclear Information System (INIS)

Barnes, S.A.; Kelly, D.E.

1992-01-01

The original designers of the UK Magnox reactor plant made provision for the then perceived time dependent processes that could have influenced the operational life of the plant. Changes in graphite properties with irradiation, particularly dimensional change, were well understood and in-core samples were provided for subsequent laboratory examination to monitor the processes throughout plant life. The tendency towards embrittlement with irradiation of the steel of the reactor pressure vessels was also acknowledged and again in-core samples were provided for monitoring changes in materials properties in-service and thus provide data in support of structural analyses to sustain the reactor safety cases. (author)

Development of techniques for monitoring corrosion in Magnox plant

International Nuclear Information System (INIS)

Haines, N.F.; Whittle, I.; Wilson, R.

1974-01-01

Steel oxidation in Magnox reactors has led to the development of techniques for measuring oxide thicknesses. An account is given of the methods used by the CEGB for making non-destructive measurements of oxide coatings both in the laboratory and remotely in the core regions of reactors. Specific techniques include β back-scattering which is compared with conventional microscope or weight gain methods for particular applications. The laser corrosion monitor and an ultrasonic method are described and compared as in-reactor techniques. An eddy current method is being developed for reactor regions where access is extremely restricted. A discussion considers the effect of oxide form upon the response of the instruments. The necessary further work is described which establishes the usefulness of each instrument over a range of oxide thicknesses and steels of different physical properties. (author)

Development and application of a welding procedure for remote repair of Magnox reactor internal components

International Nuclear Information System (INIS)

Morgan-Warren, E.J.

1988-01-01

This paper summarises the development and application of an all-welding repair method for reinforcing magnox reactor internal components. The development was dominated by the necessity for remote operation and the environmental constraints, in particular the oxide covering on the steel reactor structure. The choice of welding process is described, together with the development of the procedure for remote operation. The quality assurance procedure, including the verification of the technique and monitoring of the repair operation, is discussed. (author)

Volatilisation of ruthenium in vitrification. Isothermal calcination studies of 'Magnox' and thermal oxide simulates

International Nuclear Information System (INIS)

Cains, P.W.; Hay, D.A.

1982-12-01

Ru volatilities have been measured for the static, isothermal calcination of ''Magnox'' and Thermal Oxide HAL's (Highly Active Liquors) at temperatures up to 600 0 C. Model solutions containing Ru, HNO 3 , and nitrates of important individual cations have also been investigated. Experimental design was primarily based on the requirements of rotary calcination process development. The results have been interpreted in terms of a reaction model involving competition between the simple degradation of Ru(NO) complexes to RuO 2 and oxidative decomposition to volatile species (e.g. RuO 4 ). (author)

Individual and collective doses associated with the transport of irradiated magnox fuel within the UK

International Nuclear Information System (INIS)

Macdonald, H.F.; Mairs, J.H.

1978-12-01

A method is described of evaluating the individual and collective doses arising during the transport of irradiated fuel from a system of nuclear power stations to a central reprocessing plant. The doses associated with irradiated Magnox fuel movements in the UK are estimated and compared with those resulting from other phases of the nuclear fuel cycle. In addition, the individual and collective doses implied by the accidental activity release limits contained within the 1973 IAEA Tranport Regulations are discussed. (author)

The radioactive inventory of a decommissioned magnox power station structure. 1. Measurements of neutron induced activity in samples from the reactor island

International Nuclear Information System (INIS)

Woollam, P.B.

1978-09-01

This report is the first of a series which, together, aim to produce an accurate assessment of neutron induced activation levels in the fixed structural components of a reactor of the steel pressure vessel Magnox type. It describes the measurements made of induced activation, necessary in order to establish credibility in the complex calculations described in the subsequent reports. The report also attempts systematically to assess the potential contributions to the dose and disposal problem from all isotopes with a half-life in excess of 5 years. This is necessary in order to ensure that no isotope has been overlooked which could limit any part of the plan for the decommissioning of a Magnox reactor. In addition the report aims to determine concentrations, in each major material type, of trace elements which lead to the isotopes limiting in decommissioning. (author)

The decommissioning of commercial magnox gas cooled reactor power stations in the United Kingdom

International Nuclear Information System (INIS)

Holt, G.

1998-01-01

There are nine commercial Magnox gas-cooled reactor power stations in the United Kingdom. Three of these stations have been shutdown and are being decommissioning, and plans have also been prepared for the eventual decommissioning of the remaining operational stations. The preferred strategy for the decommissioning of the Magnox power stations has been identified as 'Safestore' in which the decommissioning activities are carried out in a number of steps separated by quiescent periods of care and maintenance. The final clearance of the site could be deferred for up to 135 years following station shutdown so as to obtain maximum benefit from radioactive decay. The first step in the decommissioning strategy is to defuel the reactors and transport all spent and new fuel off the site. This work has been completed at all three shutdown stations. Decommissioning work is continuing on the three sites and has involved activities such as dismantling, decontamination, recycling and disposal of some plant and structures, and the preparation of others for retention on the site for a period of care and maintenance. Significant experience has been gained in the practical application of decommissioning, with successful technologies and processes being identified for a wide range of activities. For example, large and small metallic and concrete structures, some with complex geometries, have been successfully decontaminated. Also, the reactors have been prepared for a long period of care and maintenance, with instrumentation and sampling systems having been installed to monitor their continuing integrity. All of this work has been done under careful safety, technical, and financial control. (author)

Annual limits on intake for aerosols in the working environment on Magnox power stations

International Nuclear Information System (INIS)

Bosch, F.G.C.; Harte, G.A.

1983-09-01

Annual Limits on Intake (ALIs) for inhaled radionuclides given by the International Commission on Radiological Protection are derived for single isotopes and for an aerosol size (AMAD) of 1 micron. A recent investigation into aerosols in the pond hall of a Magnox Power Station has demonstrated that the aerosol in the pond hall consists of particles of corroded fuel and that the size distribution has an AMAD nearer 6 microns than 1 micron. Experiments in rodents with a simulated pond hall aerosol indicate that clearance characteristics of these particles in the lung are closer to ICRP's class W classification than to any other. Accordingly ALIs were calculated as a function of particle size and for various cooling times for Magnox-fuel of burnup 3500 MWd/t and 7000 MWd/t. Separate values for alpha and beta activity were derived, based on stochastic and non-stochastic dose limits. For a 6 micron aerosol the ALI (α-activity) based on limiting the committed dose to bone surfaces lies between 120 and 320 Bq, depending on fuel burnup and cooling time. The ALI (β-activity) in the same circumstances lies between 10 4 and 8 x 10 4 Bq. Beta activity in the aerosol is dominated by the fission products but dose is overwhelmingly due to the actinides in the fuel. In addition an attempt was made to construct or to find a lung model which more closely represented the observed clearance to blood in the animal experiments. A recent model for large inhaled particles derived at the NRPB was found to give the best fit to the experimental data. ALIs derived on the basis of this model, for a 6 micron aerosol, are roughly 2 times higher than those based completely on the ICRP recommendations. (author)

The manufacture and use of sludge test materials for R and D purposes in the treatment and processing of magnox based sludge

International Nuclear Information System (INIS)

Blackburn, D.R.; Thompson, E.J.

2013-01-01

Among the Intermediate Level Waste materials in store and awaiting treatment and processing in the UK are quantities of magnesium hydroxide sludge. This sludge is a product of radioactive Magnox Swarf which arose from the de-canning of used magnox fuel element rods. As the Swarf was stored underwater, a corrosion reaction occurred over the course of time between the magnox and the water resulting in a magnesium hydroxide based sludge. The differing conditions and materials present in the various storage areas means that the sludge can range in consistency from that of a slurry through to a thick clay. Sludge test materials are required to underpin and validate the research and development equipment and processes that are to be used to treat the waste material. Necessary restrictions imposed on the sampling and testing of the radioactive waste means that the available data on the properties and behaviour of the sludge is limited. The raw materials used to create the sludge test materials are based upon magnesium hydroxide so that as far as possible the chemical behaviour will be similar to that of the waste material. The most representative sludge test material is manufactured by the corrosion of non-radioactive magnox or magnesium. However, time constraints make it impractical to supply this material in sufficient quantities for full scale validation trials. An alternative is to use sludge manufactured from commercially available magnesium hydroxide. The particle shape of commercially available materials differs from corrosion product magnesium hydroxide which means that properties such as the rheological behaviour cannot be replicated. Nevertheless, valuable trial data can be obtained, giving a greater degree of confidence in the waste treatment process than would be possible if only the more representative but less available corrosion product materials were to be used. Key test material parameters used in the trials have been identified as the particle size

The manufacture and use of sludge test materials for R and D purposes in the treatment and processing of magnox based sludge

Energy Technology Data Exchange (ETDEWEB)

Blackburn, D.R.; Thompson, E.J. [NSG Environmental Ltd, Chorley, Lancashire (United Kingdom)

2013-07-01

Among the Intermediate Level Waste materials in store and awaiting treatment and processing in the UK are quantities of magnesium hydroxide sludge. This sludge is a product of radioactive Magnox Swarf which arose from the de-canning of used magnox fuel element rods. As the Swarf was stored underwater, a corrosion reaction occurred over the course of time between the magnox and the water resulting in a magnesium hydroxide based sludge. The differing conditions and materials present in the various storage areas means that the sludge can range in consistency from that of a slurry through to a thick clay. Sludge test materials are required to underpin and validate the research and development equipment and processes that are to be used to treat the waste material. Necessary restrictions imposed on the sampling and testing of the radioactive waste means that the available data on the properties and behaviour of the sludge is limited. The raw materials used to create the sludge test materials are based upon magnesium hydroxide so that as far as possible the chemical behaviour will be similar to that of the waste material. The most representative sludge test material is manufactured by the corrosion of non-radioactive magnox or magnesium. However, time constraints make it impractical to supply this material in sufficient quantities for full scale validation trials. An alternative is to use sludge manufactured from commercially available magnesium hydroxide. The particle shape of commercially available materials differs from corrosion product magnesium hydroxide which means that properties such as the rheological behaviour cannot be replicated. Nevertheless, valuable trial data can be obtained, giving a greater degree of confidence in the waste treatment process than would be possible if only the more representative but less available corrosion product materials were to be used. Key test material parameters used in the trials have been identified as the particle size

The complex challenge of repairing the gantry steelwork on the first generation magnox storage pond at Sellafield: Legacy Waste Storage, First Generation Magnox Storage Pond - 59133

International Nuclear Information System (INIS)

Richardson, Ian E.

2012-01-01

This paper puts into context the challenges that were faced when repairing the Gantry Steelwork of the First Generation Magnox Storage Pond (FGMSP). The First Generation Magnox Fuel Storage Pond (FGMSP) provided fuel storage and de-canning capability from the early 1960's until 1986. A significant programme of work has been underway since the completion of operational activities to support the programmes strategic intent of retrieving and storing all legacy wastes, and remediating the structure of the plant to support decommissioning activities. A key enabler to the retrievals programme is the Pond Skip Handler Machine (SHM), removed from service in 2002 following the discovery of significant signs of corrosion and distress, an inevitable consequence of being located in a coastal, salt laden environment. The SHM provides sole capability to access and retrieve the inventory of over 1000 fuel skips. It is also fundamental to future operations and the deployment of de-sludging equipment to recover significant bulk sludge's from the pond floor. Failure of the SHM steelwork gantry at worst case could potentially result in the Skip Handler Machine being derailed. This has some potential to damage to the pond structure and at worst case may result in local radiological and environmental consequences. This paper will examine the challenges faced by the team as they successfully defined, planned and executed remedial work to a specific aspect of the civil structure, the SHM gantry rail system, using a purpose built refurbishment platform; the Gantry Refurbishment System. The paper will examine how an 'innovative' approach was adopted to resolve the related issues of: - Refurbishing an aged structure to meet extended future operational demands. - The application of pragmatic engineering solutions against current codes and standards including seismic performance; - Provision of safe access for the workforce to undertake the refurbishment work against significant radiological

The ratio between the decay heat output and activity content of discharged magnox fuel

International Nuclear Information System (INIS)

Davies, B.S.J.

1977-01-01

Values of the ratio between activity and heat production rate have been calculated for magnox fuel irradiated to 3500 and 8000 MWd.Te -1 and for cooling times of 100, 200 and 500 days. Results are expressed in terms of both MeV.decay -1 and MCi.KW -1 . The results indicate that: for these irradiation and cooling conditions 21 nuclides account for over 99% of the total activity; the calculated values show only small variations with burn-up and cooling time, although the mean energy per decay does fall slightly at 500 days cooling: so for many purposes a median value of 0.63 MeV.decay -1 (0.27 MCi.MW -1 ) may be used; the calculated values have standard deviations ranging from 2.6% at 100 days cooling to 9% at 500 days cooling. (author)

An analysis of ingestion doses from a range of postulated Magnox reactor releases

International Nuclear Information System (INIS)

Nair, S.

1985-06-01

An analysis has been carried out of ingestion doses from a range of postulated Magnox reactor releases to atmosphere. Calculations were made of the dose to the adult, ten year old child and one year old child, which showed the one year old child to receive the highest dose. Detailed studies were made of the significance of the ingestion dose to the one year old child in relation to other exposure routes. The ingestion dose was also analysed in terms of the contributing critical organs, foods and nuclides. Approximate calculations were also made of the dependence of the ingestion dose on the time of year when the release occurs. The results of the analysis were used to derive a set of release-specific Emergency Action Guidance Levels (EAGLs) of critical nuclide concentrations in the critical foods, which comply with NRPB's ingestion ERL recommendations. The EAGLs were supplemented with a corresponding set of EAGLs for grass, for use in situations where crop samples were not readily available. (author)

An investigation of magnox sludge and alumino-ferric floc waste simulate, immobilised by a cementitious matrix

International Nuclear Information System (INIS)

Halley, D.G.

1983-09-01

Magnox sludge and alumino ferric floc simulates, prepared using non-radioactive tracers were immobilised by a cementitious system. Formulation design aimed at optimising pollutant leaching with permeability and compressive strength as secondary considerations. The behaviour of the products under accelerated weathering conditions was investigated. The study was divided into two parts: Formulation design in Phase I and the systematic testing of the optimum formulations under freeze-thaw, and hydration -dehydration conditions in Phase 2. Analytical method development for leachate analysis continued through both Phases. The Barnwood method of leach testing was used. The immobilised waste had good physical properties (i.e. high strength and low permeability) and a significant improvement was achieved during the course of the work in the leach rates of the tracers, particularly of caesium and strontium. (author)

Graphite materials testing in the ATR for lifetime management of Magnox reactors

International Nuclear Information System (INIS)

Grover, S.B.; Metcalfe, M.P.

2002-01-01

A major feature of the Magnox gas cooled reactor design is the graphite core, which acts as the moderator but also provides the physical structure for fuel, control rods, instrumentation and coolant gas channels. The lifetime of a graphite core is dependent upon two principal aging processes: irradiation damage and radiolytic oxidation. Irradiation damage from fast neutrons creates lattice defects leading to changes in physical and mechanical properties and the accumulation of stresses. Radiolytic oxidation is caused by the reaction of oxidizing species from the carbon dioxide coolant gas with the graphite, these species being produced by gamma radiation. Radiolytic oxidation reduces the density and hence the moderating capability of the graphite, but also reduces strength affecting the integrity of core components. In order to manage continued operation over the planned lifetimes of their power stations, BNFL needed to extend their database of the effects of these two phenomena on their graphite cores through an irradiation experiment. This paper will discuss the background, purpose, and the processes taken and planned (i.e. post irradiation examination) to ensure meaningful data on the graphite core material is obtained from the irradiation experiment. (author)

Graphite Materials Testing in the ATR for Lifetime Management of Magnox Reactors

International Nuclear Information System (INIS)

Grover, S.B.; Metcalfe, M.P.

2002-01-01

A major feature of the Magnox gas cooled reactor design is the graphite core, which acts as the moderator but also provides the physical structure for fuel, control rods, instrumentation and coolant gas channels. The lifetime of a graphite core is dependent upon two principal aging processes: irradiation damage and radiolytic oxidation. Irradiation damage from fast neutrons creates lattice defects leading to changes in physical and mechanical properties and the accumulation of stresses. Radiolytic oxidation is caused by the reaction of oxidizing species from the carbon dioxide coolant gas with the graphite, these species being produced by gamma radiation. Radiolytic oxidation reduces the density and hence the moderating capability of the graphite, but also reduces strength affecting the integrity of core components. In order to manage continued operation over the planned lifetimes of their power stations, BNFL needed to extend their database of the effects of these two phenomena on the ir graphite cores through an irradiation experiment. This paper will discuss the background, purpose, and the processes taken and planned (i.e. post irradiation examination) to ensure meaningful data on the graphite core material is obtained from the irradiation experiment

An analysis of ingestion doses from a range of postulated Magnox reactor releases

International Nuclear Information System (INIS)

Nair, S.

1986-01-01

An analysis was carried out of ingestion doses from a range of postulated Magnox reactor releases to the atmosphere. Doses to the adult, ten year old child and one year old child were calculated, which showed the one year old child to receive the highest dose. Detailed studies were made of the significance of the ingestion dose to the one year old child in relation to other exposure routes. The ingestion dose was analysed for its contributing critical organs, foods and nuclides. Approximate calculations were also made of the dependence of the ingestion dose on the time of year when the release occurs. The ingestion pathway was found to dominate if the release occurs towards the end of the growing season but to be less significant relative to other exposure pathways at all other times. The calculations enabled a set of release-specific emergency action guidance levels of critical nuclide concentrations in the critical foods to be produced, which comply with NRPB's ingestion Emergency Reference Level guidelines. (author)

Review of operational experience with the gas-cooled Magnox reactors of the United Kingdom Central Electricity Generating Board

International Nuclear Information System (INIS)

Cave, L.; Clarke, A.W.

1984-01-01

The paper provides a review, which is mainly of a statistical nature, of 260 reactor years of operating experience which the (United Kingdom) Central Electricity Generating Board (CEGB) has obtained with its gas-cooled, graphite moderated Magnox reactors. The main emphasis in the review is on safety rather than on availability. Data are provided on the overall incidence and frequencies of faults and it is shown that the plant items which are predominantly responsible for recorded faults are the gas circulators and the turbo-alternators. Analysis of the reactor trip experience shows that the incidence of events which necessitate an automatic shutdown of the reactor has been about one per reactor year and that of other events leading to a reactor trip has not been much higher (1.4 per reactor year). As would be expected from the length of the operating experience, some relatively rare events have occurred (expected frequency 10 -2 per reactor year, or less) but on each occasion the reactor shutdown system and decay heat removal systems functioned satisfactorily. No overheating of, or damage to, the fuel occurred as a result of these rare events or of other, more frequent, faults. Analysis of the trend of failure rates has shown an improvement with time in nearly all safety-related items and external inspection of the primary coolant circuits has shown no significant deterioration with time. However, some derating of the reactors has been necessary to reduce the effects of oxidation of mild steel in CO 2 , in order to obtain optimum service lives. In spite of major differences between the systems, a comparison of the failure rates of analogous systems and plant items in PWRs and the Magnox reactors show a considerable similarity. Overall, the review of CEGB's operational experience with its Magnos reactors has shown that the frequencies of faults in systems and plant items has been satisfyingly low. (author)

Modelling of the anti-neutrino production and spectra from a Magnox reactor

Science.gov (United States)

Mills, Robert W.; Mountford, David J.; Coleman, Jonathon P.; Metelko, Carl; Murdoch, Matthew; Schnellbach, Yan-Jie

2018-01-01

The anti-neutrino source properties of a fission reactor are governed by the production and beta decay of the radionuclides present and the summation of their individual anti-neutrino spectra. The fission product radionuclide production changes during reactor operation and different fissioning species give rise to different product distributions. It is thus possible to determine some details of reactor operation, such as power, from the anti-neutrino emission to confirm safeguards records. Also according to some published calculations, it may be feasible to observe different anti-neutrino spectra depending on the fissile contents of the reactor fuel and thus determine the reactor's fissile material inventory during operation which could considerable improve safeguards. In mid-2014 the University of Liverpool deployed a prototype anti-neutrino detector at the Wylfa R1 station in Anglesey, United Kingdom based upon plastic scintillator technology developed for the T2K project. The deployment was used to develop the detector electronics and software until the reactor was finally shutdown in December 2015. To support the development of this detector technology for reactor monitoring and to understand its capabilities, the National Nuclear Laboratory modelled this graphite moderated and natural uranium fuelled reactor with existing codes used to support Magnox reactor operations and waste management. The 3D multi-physics code PANTHER was used to determine the individual powers of each fuel element (8×6152) during the year and a half period of monitoring based upon reactor records. The WIMS/TRAIL/FISPIN code route was then used to determine the radionuclide inventory of each nuclide on a daily basis in each element. These nuclide inventories were then used with the BTSPEC code to determine the anti-neutrino spectra and source strength using JEFF-3.1.1 data. Finally the anti-neutrino source from the reactor for each day during the year and a half of monitored reactor

Modelling of the anti-neutrino production and spectra from a Magnox reactor

Directory of Open Access Journals (Sweden)

Mills Robert W

2018-01-01

Full Text Available The anti-neutrino source properties of a fission reactor are governed by the production and beta decay of the radionuclides present and the summation of their individual anti-neutrino spectra. The fission product radionuclide production changes during reactor operation and different fissioning species give rise to different product distributions. It is thus possible to determine some details of reactor operation, such as power, from the anti-neutrino emission to confirm safeguards records. Also according to some published calculations, it may be feasible to observe different anti-neutrino spectra depending on the fissile contents of the reactor fuel and thus determine the reactor's fissile material inventory during operation which could considerable improve safeguards. In mid-2014 the University of Liverpool deployed a prototype anti-neutrino detector at the Wylfa R1 station in Anglesey, United Kingdom based upon plastic scintillator technology developed for the T2K project. The deployment was used to develop the detector electronics and software until the reactor was finally shutdown in December 2015. To support the development of this detector technology for reactor monitoring and to understand its capabilities, the National Nuclear Laboratory modelled this graphite moderated and natural uranium fuelled reactor with existing codes used to support Magnox reactor operations and waste management. The 3D multi-physics code PANTHER was used to determine the individual powers of each fuel element (8×6152 during the year and a half period of monitoring based upon reactor records. The WIMS/TRAIL/FISPIN code route was then used to determine the radionuclide inventory of each nuclide on a daily basis in each element. These nuclide inventories were then used with the BTSPEC code to determine the anti-neutrino spectra and source strength using JEFF-3.1.1 data. Finally the anti-neutrino source from the reactor for each day during the year and a half of

Magnox Fuel Cycles; Cycles des combustibles gaines de magnox; Toplivnye tsikly magnoks; Ciclos de combustible magnox

Energy Technology Data Exchange (ETDEWEB)

Johnson, A. [United Kingdom Atomic Energy Authority, Risley, Warrington, Lancs (United Kingdom)

1963-10-15

The interaction between reactivity flux and temperature distributions and irradiation patterns caused by different refuelling policies is considered and present calculation methods outlined. Various refuelling schemes for both batch and continuous discharge systems are compared. The problem of the efficient irradiation of the first charge is considered together with delayed onset refuelling and shuffling schemes. The economic advantages and problems of using non-natural uranium in flattened reactors are discussed. The practical consideration of on-load refuelling schemes on new reactors are considered and reference is made to the experience gained on Bradwell and Berkeley. The effect of the variation of fuel cost and endurance on fuel-cycle economics is outlined. (author) [French] L'auteur etudie en premier lieu l'interaction entre les distributions de la temperature du flux et de la reactivite, d'une part, et le regime de l'irradiation, d'autre part, dans le cas de differents programmes de rechargement du combustible et il decrit brievement les methodes de calcul actuelles. Il compare ensuite differents programmes de rechargement du combustible pour le dechargement par lots et le dechargement continu. Il etudie le probleme de l'irradiation effica ce de la premiere charge dans le cadre de programmes de remplacement et de deplacement des cartouches a action retardee. Il analyse les avantages economiques de l'utilisatio n d'uranium non naturel dans les reacteurs a flux aplati et les problemes qu'elle pose. Il examine les aspects pratiques des programmes de rechargement en marche pour les nouveaux reacteurs, en se referant a l'experience acquise au moyen des reacteurs de Bradwell et de Berkeley. Enfin, il decrit brievement les effets des variations du cout et de la resistance du combustible sur l'economie des cycles de combustible. (author) [Spanish] La memoria estudia la interaccion entre el flujo de reactividad y la distribucion de temperaturas, asi como los esquemas de irradiacion que se producen segun los diversos programas de carga del combustible, y describe someramente los metodos de calculo utilizados en la actualidad. Compara diversos programas de carga continua o intermitente del combustible. Estudia el problema de la irradiacion eficiente de la primera carga, junto con los metodos de reabastecimiento retardado y de transposicion de los elementos combustibles. Discute las ventajas economicas y los problemas que plantea la utilizacion de uranio, no natural en reactores de flujo nivelado. Formula consideraciones de orden practico sobre la carga de combustible durante la marcha en reactores nuevos y hace referencia a la experiencia adquirida en Bradwell y en Berkeley. Describe someramente el efecto que ejercen las variaciones del costo del combustible y de su resistencia sobre los aspectos economicos del ciclo de combustible. (author) [Russian] Rassmatrivaetsya vzaim o zavisimost' mezhdu potokom izlucheniya i temperaturnym raspredeleniem i kharakteristikami oblucheniya, vyzvannaya razlichnoj praktikoj zameny topliva, opisyvayutsya sushchestvuyushchie metody rascheta. Provoditsya sravnenie razlichnykh skhem zameny topliva, vklyuchaya kak sistemu vygruzki topliva portsiyami, tak i sistemu nepreryvnoj vygruzki. Problema ehffektivnogo oblucheniya pervoj zagruzki rassmatrivaetsya vmeste so skhemami zapazdyvayushchej nachal'noj zameny topliva i ego peremeshcheniya. Rassmatrivayutsya ehkonomicheskie preimushchestva i trudnosti ispol'zovaniya neprirodnogo urana v vyrovnennykh reaktorakh. Rassmatrivaetsya prakticheskoe reshenie skhemy zameny topliva na novykh reaktorakh i delaetsya ssylka na opyt, priobretennyj v Braduehlle i Berkli. Opisyvaetsya vliyani razlichnoj stoimosti topliva i prodolzhitel'nosti kampanii za ehkonomichnost' toplivnogo tsikla. (author)

The CEGB/SSEB response to Recommendation 17 in the Environment Committee's Report on Radioactive Waste. V.1

International Nuclear Information System (INIS)

1986-11-01

The first report from the Environment Committee concerning radioactive waste was published on 12th March 1986. Recommendation 17 of the Committee's report asked the CEGB and SSEB (the Home Boards) to carry out and publish an analysis of the costs of backfitting dry stores to Magnox stations and compare this with the costs of reprocessing, vitrification and subsequent storage of vitrified HLW. In addition the Committee asked that the Home Boards should examine the feasibility of drying Magnox spent fuel once it had been wet in the cooling ponds. This report represents the Home Boards' response to Recommendation 17. In addition, in order to provide a comprehensive economic comparison, consideration has also been given to the likely range of costs for treatment and final disposal of Magnox spent fuel. In carrying out this study the Home Boards have assessed the technical feasibility, costs and likely timescales associated with establishing new all-dry discharge routes on each of the individual Magnox stations and constructing dry storage facilities suitable for storing Magnox fuel for up to 100 years. (author)

The CEGB/SSEB response to Recommendation 17 in the Environment Committee's Report on Radioactive Waste. V.2

International Nuclear Information System (INIS)

1986-11-01

Assuming a government policy decision or a joint CEGB/SSEB decision to store rather than reprocess Magnox spent fuels alternative programmes for planning for the dry storage of spent fuels at each Magnox station or a central site are considered. The importance of the time required to obtain planning permission is emphasised. (U.K.)

Mechanistic investigation of internal corrosion in nuclear waste containers over extended time periods

International Nuclear Information System (INIS)

Onumonu, E.; Stevens, D. N. P. C.

2008-01-01

Storage of the UK's Intermediate Level Wastes (ILW), which comprises Magnox fuel cladding, uranium and small items of equipment exposed to radiation, is currently achieved via encapsulation within cementitious grout housed in 500 litre 316L stainless steel drums. The cements used display a high pH; in such an environment many metals form surface hydroxides or oxides. Magnox reacts with free water at high pH with the liberation of hydrogen whilst undergoing corrosion to form hydroxide species. Corrosion of Magnox cladding has previously been monitored by measuring the rate of hydrogen evolution and/or weight loss. Recent work by our group has shown impedance techniques may also be useful in monitoring early corrosion behaviour. In this project electrochemical polarisation techniques will be employed to examine the corrosion behaviour of Magnox fuel in situations where it is in electrical contact with other metals, including uranium, and hence determine how galvanic effects influence corrosion behaviour. In this paper we describe the background to such experiments along with some preliminary results. (authors)

Turning off the power

International Nuclear Information System (INIS)

Wyman, Vic.

1988-01-01

The decision to close the Berkeley Magnox nuclear power station in 1988 is reported and the implications for the other Magnox plants in the UK are discussed. Conflicting accounts of the economics of those stations, as derived by the CEGB and Friends of the Earth are reported. Finally the contrasting experience with the Scottish generating boards is discussed. (U.K.)

Sellafield

International Nuclear Information System (INIS)

1984-01-01

This small, illustrated, booklet describes Sellafield under the headings: introduction (historical and general); organisation (Windscale Works; Calder Works); Magnox reprocessing (using nuclear fuel in a reactor; transport of fuel; used fuel stored in ponds; decanning of Magnox fuel; separation process; highly-active storage tanks; vitrification); waste disposal; health and safety; Calder Hall; future developments; training young people; community relations. (U.K.)

Encapsulation of aluminium in geopolymers produced from metakaolin

Energy Technology Data Exchange (ETDEWEB)

Kuenzel, C. [Department of Civil and Environmental Engineering, Imperial College London (United Kingdom); Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London (United Kingdom); Neville, T.P. [Centre for CO_2 Technology, Department of Chemical Engineering, University College London (United Kingdom); Omakowski, T. [Flowcrete, Group Ltd., Cheshire (United Kingdom); Vandeperre, L. [Centre for Advanced Structural Ceramics, Department of Materials, Imperial College London (United Kingdom); Boccaccini, A.R. [Institute of Biomaterials, University of Erlangen-Nuremberg (Germany); Bensted, J.; Simons, S.J.R. [Centre for CO_2 Technology, Department of Chemical Engineering, University College London (United Kingdom); Cheeseman, C.R., E-mail: c.cheeseman@imperial.ac.uk [Department of Civil and Environmental Engineering, Imperial College London (United Kingdom)

2014-04-01

Magnox swarf contaminated with trace levels of Al metal is an important UK legacy waste originated from the fuel rod cladding system used in Magnox nuclear power stations. Composite cements made from Portland cement and blast furnace slag form a potential encapsulation matrix. However the high pH of this system causes the Al metal to corrode causing durability issues. Geopolymers derived from metakaolin are being investigated as an alternative encapsulation matrix for Magnox swarf waste and the corrosion kinetics and surface interactions of Al with metakaolin geopolymer are reported in this paper. It is shown that the pH of the geopolymer paste can be controlled by the selection of metakaolin and the sodium silicate solution used to form the geopolymer. A decrease in pH of the activation solution reduces corrosion of the Al metal and increases the stability of bayerite and gibbsite layers formed on the Al surface. The bayerite and gibbsite act as a passivation layer which inhibits further corrosion and mitigates H{sub 2} generation. The research shows that optimised metakaolin geopolymers have potential to be used to encapsulate legacy Magnox swarf wastes.

Product evaluation phase 1 report

International Nuclear Information System (INIS)

Fairhall, G.A.

1984-01-01

This report concerns the intermediate-level radioactive waste arisings from the reprocessing of magnox-clad fuel at BNFL Sellafield. The magnox swarf, with its associated debris, retrieved from previous operations has corroded to a sludge. Headings are: introduction (origin, current stocks and future arisings); waste characterisation; initial evaluation of potential matrices for solidification of waste in form suitable for disposal; waste simulation. (U.K.)

Partnership - its contribution to outage success

International Nuclear Information System (INIS)

Gill, K.S.; Kirton-Darling, F.; Robinson, F.T.

1996-01-01

An innovative approach to developing the teamwork between the power station and the outage contractor has been pioneered over the past three years at the Bradwell nuclear power station in the UK, which houses two Magnox reactors. Magnox Electric and Rolls-Royce Nuclear Engineering Services are now undertaking their third outage under a partnership contract which has provided significant benefits to both parties. (Author)

Recent development of fuelling grabheads and associated control equipment

International Nuclear Information System (INIS)

Carter, C.C.

1984-01-01

GEC Energy Systems has designed, developed, manufactured and supplied refuelling grabheads from the beginning of the Magnox nuclear power programme through to the present day. Early grabheads were mechanically complex, and a major rationalization of the grabhead design philosophy was developed in the late 1960s with the introduction of the solenoid operated grab. This paper describes the design features and development of solenoid operated grabs as used in CEGB and JAPC Magnox reactors. (author)

What will we do with the low level waste from reactor decommissioning?

International Nuclear Information System (INIS)

Meehan, A. R.; Wilmott, S.; Crockett, G.; Watt, N. R.

2008-01-01

The decommissioning of the UK's Magnox reactor sites will produce large volumes of low level waste (LLW) arisings. The vast majority of this waste takes the form of concrete, building rubble and redundant plant containing relatively low levels of radioactivity. Magnox Electric Ltd (Magnox) is leading a strategic initiative funded by the Nuclear Decommissioning Authority (NDA) to explore opportunities for the disposal of such waste to suitably engineered facilities that might be located on or adjacent to the site of waste arising, if appropriate and subject to regulatory acceptance and stakeholder views. The strategic issues surrounding this initiative are described along with an update of progress with stakeholder consultations in relation to the proposed licensing of the first such facility at Hinkley Point A, which could be viewed as a test case for the development of similar disposal facilities at other nuclear sites in England and Wales. (authors)

Operational and reliability experience with reactor instrumentation

International Nuclear Information System (INIS)

Dixon, F.; Gow, R.S.

1978-01-01

In the last 15 years the CEGB has experienced progressive plant development, integration and changes in operating regime through nine nuclear (gas-cooled reactor) power stations with corresponding instrumentation advances leading towards more refined centralized control. Operation and reliability experience with reactor instrumentation is reported in this paper with reference to the progressive changes related to the early magnox, late magnox and AGR periods. Data on instrumentation reliability in terms of reactor forced outages are presented and show that the instrumentation contributions to loss of generating plant availability are small. Reactor safety circuits, neutron flux and temperature measurements, gas analysis and vibration monitoring are discussed. In reviewing the reactor instrumentation the emphasis is on reporting recent experience, particularly on AGR equipment, but overall performance and changes to magnox equipment are included so that some appreciation can be obtained of instrumentation requirements with respect to plant lifetimes. (author)

Nuclear privatization

International Nuclear Information System (INIS)

Jeffs, E.

1995-01-01

The United Kingdom government announced in May 1995 plans to privatize the country's two nuclear generating companies, Nuclear Electric and Scottish Nuclear. Under the plan, the two companies will become operating divisions of a unified holding company, to be called British Electric, with headquarters in Scotland. Britain's nuclear plants were left out of the initial privatization in 1989 because the government believed the financial community would be unwilling to accept the open-ended liability of decommissioning the original nine stations based on the Magnox gas-cooled reactor. Six years later, the government has found a way around this by retaining these power stations in state ownership, leaving the new nuclear company with the eight Advanced Gas-cooled Reactor (AGR) stations and the recently completed Sizewell B PWR stations. The operating Magnox stations are to be transferred to BNFL, which operates two Magnox stations of their own at Calder Hall and Chapelcross

Graphics and control for in-reactor operations

International Nuclear Information System (INIS)

Smith, A.L.

1996-01-01

Remotely operated inspection, repair and maintenance tasks for Magnox Electric's eight twin MAGNOX-type reactor stations must conform to the Nuclear Installations Inspectorate's regulations. The performance of manipulator systems used to undertake such operations has improved significantly with the recent introduction of computer graphics. These are used for simulation and demonstration purposes as well as a real-time aid to the manipulator operator. Outage times can be reduced by the appropriate use of such computer technology to reduce manipulator operation times. (UK)

The status of spent fuel storage in the UK

International Nuclear Information System (INIS)

Dunn, M.J.; Topliss, I.R.

1999-01-01

Nuclear generating capacity in the UK is static with no units currently under construction. There are three main nuclear fuel types used in the UK for Magnox reactors, AGRs and PWRs. All Magnox fuel will ultimately be reprocessed following a short period of interim storage. AGR fuel will either be reprocessed or long term stored in ponds. PWR fuel will be stored underwater at the reactor site for the foreseeable future, with no decision as yet made to its ultimate management route. (author)

Synthesis of carbon-13 labelled carbonaceous deposits and their evaluation for potential use as surrogates to better understand the behaviour of the carbon-14-containing deposit present in irradiated PGA graphite

Energy Technology Data Exchange (ETDEWEB)

Payne, L., E-mail: liam.payne@bristol.ac.uk [Interface Analysis Centre, HH Wills Physics Laboratory, University of Bristol, BS8 1TL (United Kingdom); Walker, S.; Bond, G. [Centre for Materials Science, University of Central Lancashire, PR1 2HE (United Kingdom); Eccles, H. [John Tyndall Institute for Nuclear Research, School of Computing, Engineering and Physical Sciences, University of Central Lancashire, PR1 2HE (United Kingdom); Heard, P.J.; Scott, T.B. [Interface Analysis Centre, HH Wills Physics Laboratory, University of Bristol, BS8 1TL (United Kingdom); Williams, S.J. [Radioactive Waste Management, B587, Curie Avenue, Harwell Oxford, Didcot, OX11 0RH (United Kingdom)

2016-03-15

The present work has used microwave plasma chemical vapour deposition to generate suitable isotopically labelled carbonaceous deposits on the surface of Pile Grade A graphite for use as surrogates for studying the behaviour of the deposits observed on irradiated graphite extracted from UK Magnox reactors. These deposits have been shown elsewhere to contain an enhanced concentration of {sup 14}C compared to the bulk graphite. A combination of Raman spectroscopy, ion beam milling with scanning electron microscopy and secondary ion mass spectrometry were used to determine topography and internal morphology in the formed deposits. Direct comparison was made against deposits found on irradiated graphite samples trepanned from a Magnox reactor core and showed a good similarity in appearance. This work suggests that the microwave plasma chemical vapour deposition technique is of value in producing simulant carbon deposits, being of sufficiently representative morphology for use in non-radioactive surrogate studies of post-disposal behaviour of {sup 14}C-containing deposits on some irradiated Magnox reactor graphite.

Review of UK participation in ASSET activities 1995/96 for the annual workshop on ASSET experience

International Nuclear Information System (INIS)

Phipps, C.R.

1996-01-01

With the restructuring of the Nuclear Generation Industry in the UK over the last 12 months it has been difficult to provide support to international activities including ASSET. This is likely to continue for a further 12 months whilst consolidation of the privatised part of the industry takes place and Magnox Electric plc is merged with British Nuclear Fuels Ltd. Having made that statement I would confirm that the UK is fully supportive of the ASSET methodology and will continue to be a participant in as many ASSET activities as possible. It was noted that during 1995 ASSET completed its 100th mission and the UK would like to congratulate the staff in the IAEA on this achievement. Discussions are at present ongoing within Magnox Electric plc, regarding the possibility of hosting an ASSET Peer Review mission, at one of the UK's Magnox plants, in 1997/98. During the 1995/96 period the UK participated in a number of ASSET activities as detailed below

Review of UK participation in ASSET activities 1995/96 for the annual workshop on ASSET experience

Energy Technology Data Exchange (ETDEWEB)

Phipps, C R

1997-12-31

With the restructuring of the Nuclear Generation Industry in the UK over the last 12 months it has been difficult to provide support to international activities including ASSET. This is likely to continue for a further 12 months whilst consolidation of the privatised part of the industry takes place and Magnox Electric plc is merged with British Nuclear Fuels Ltd. Having made that statement I would confirm that the UK is fully supportive of the ASSET methodology and will continue to be a participant in as many ASSET activities as possible. It was noted that during 1995 ASSET completed its 100th mission and the UK would like to congratulate the staff in the IAEA on this achievement. Discussions are at present ongoing within Magnox Electric plc, regarding the possibility of hosting an ASSET Peer Review mission, at one of the UK`s Magnox plants, in 1997/98. During the 1995/96 period the UK participated in a number of ASSET activities as detailed below.

The curious accountancy of decommissioning

International Nuclear Information System (INIS)

Anon.

1990-01-01

Financial provision for the decommissioning and waste management of the United Kingdom Magnox and AGR reactor is discussed. In the last set of accounts prior to privatisation a decommissioning provision of Pound 8.34 bn was indicated whereas previous figures had only shown Pound 2.88. It is suggested that the increase was only achieved on paper, without real financial provision. Estimates of decommissioning costs for the Magnox stations have increased greatly. Cost estimates for AGR decommissioning have still to be released but it is expected that the post-privatisation owners of the nuclear power industry, Nuclear Electric, will have to find Pound 6-7 bn to dismantle its own reactors. Much of this it hopes to put off for over 100 years. The South of Scotland Electicity Board has made much more realistic provision for its own Magnox and two AGR stations. Reprocessing costs for AGR reactor fuel is uncertain and high reprocessing and decommissioning costs will mean increases in the price of nuclear electricity. (UK)

Reprocessing and waste management in the UK

International Nuclear Information System (INIS)

Mogg, C.S.; Howarth, G.G.

1987-01-01

The paper concerns the progress in irradiated fuel reprocessing and waste management at the Sellafield site. Magnox fuel reprocessing is reviewed and oxide fuel reprocessing, due to commence in the early 1990s, is compared with existing practices. The article describes how magnox fuel reprocessing will be sustained by recent additions of new plant and shows how waste management downstream of reprocessing will be integrated across the Sellafield site. This article was first presented as a paper at the Waste Management '87 (1-5 March, Tucson, Arizona) conference. (author)

The long and short of dry vault storage [for spent fuel

International Nuclear Information System (INIS)

Bradley, N.; O'Tallamhain, C.; Grine, C.J.

1984-01-01

The case has been made for purchasing Magnox reactors outside the UK without any prior commitment to reprocessing, the fuel being stored for an interim period. Two alternative storage concepts using natural draught air-cooled vaults have been presented, one based upon experience of 'buffer' storage at gas-cooled reactors in Britain, and te second based on the long term 'interim' storage developed to a detailed design stage for British AGRs. Although storage scenarios for new Magnox stations are discussed, they may also be of interest in relation to other types of reactor. (U.K.)

The influence of zeta potential and yield stress on the filtration characteristics of a magnesium hydroxide simulant

International Nuclear Information System (INIS)

Biggs, Simon; Nabi, Rafiq; Poole, Colin; Patel, Ashok

2007-01-01

In the UK, irradiated fuels from Magnox reactors are often stored in water-filled ponds under alkaline conditions, so as to minimise corrosion of fuel cladding. This is important to prevent or reduce leakage of soluble fission products and actinides to the pond water. A variety of intermediate level wastes derived from Magnox materials are stored at power stations. Under these alkaline conditions, various species of magnesium are formed, of which magnesium hydroxide is the dominant material. The particle-fluid interactions are significant for the design and operation of facilities for hydraulic retrieval, filtration, dewatering and ion exchange treatment of fuel storage pond water and stored wet Magnox wastes. Here we describe a study of particulate properties and filtration characteristics of oxide particle simulants under laboratory conditions. Cake and medium resistance data were correlated across a range of pH conditions with electro-acoustic zeta potential and shear yield stress measurements, as a function of particle volume fractions. The influence of zeta potential on filtration properties arises directly from the interaction of particles within the sediment cake. (authors)

The UK gas-cooled reactor programme - Progress report 1988

International Nuclear Information System (INIS)

Askew, J.R.

1989-01-01

This paper summarises key developments during 1988 on the 26 Magnox reactors and 14 AGRs now operating in the UK. Details are given of long-term safety reviews of the Berkeley and Bradwell Magnox stations which resulted in a decision by CEGB to cease generation at Berkeley but to continue operation at Bradwell. The summary of operating experience with the AGRs concentrates on the completion of construction and successful commissioning of the second generation AGRs at Heysham 2 and Torness. An appended article by John Wilson, Deputy Director of the UKAEA's gas-cooled reactor R and D programme, gives details of the aims and achievements of the programme during 1988. (author)

Nuclear Electric flask design and safety case development during the last ten years

International Nuclear Information System (INIS)

Dougall, I.; Jones, D.K.

1994-01-01

The scope of Nuclear Electric's (NE) requirements for irradiated fuel transport and the relevant safety and regulatory compliance standards are outlined. To illustrate NE's approach to demonstrating package design compliance the basis of the safety case for unbottled Magnox fuel transport in the Mk M2 Magnox flask is described. The considerations which lay behind the development of the Mk A2 AGR Flask are indicated and a description is given of the main design features of this flask. Finally there is a summary of progress in obtaining Type B(M) approvals, based on the 1985 IAEA Regulations, for the requisite range of flask contents. (author)

Decommissioning in British Nuclear Fuels plc

International Nuclear Information System (INIS)

Colquhoun, A.

1988-01-01

Decommissioning projects at the BNFL Sellafield site have been selected taking the following into account; the need to gain experience in preparation for the decommissioning of the Magnox reactors and for the post Magnox stage; the need to develop larger scale projects; the need to be cost effective and to foster long term safety. The balance between prompt or delayed decommissioning has to consider operator dose uptake and radioactive waste management. The ten year plan for decommissioning at Sellafield is described briefly. Currently decommissioning is of the fuel pond and decanning plant, the Windscale Pile Chimneys, the coprecipitation plant and the uranium recovery plant. (author)

The moderator's moderator

International Nuclear Information System (INIS)

Williamson, G.K.

1990-01-01

A brief account is given of the development of graphite moderators for Magnox and advanced gas cooled reactors. The accident at Windscale in 1957 brought to worldwide attention the importance of irradiation damage in graphite and the consequent storage of Wigner energy. In spite of the Windscale setback, preparations for the civil programme of Magnox reactors went ahead apace. Some of the background to the disastrous Dungeness B tender is presented. In spite of all the difficulties and uncertainties, the graphite in UK reactors has performed well. In all cases, as far as the author is aware, the behaviour of the graphite moderators will not prevent design life being achieved. (author)

Radioactive waste. Policy and perspective

Energy Technology Data Exchange (ETDEWEB)

Roberts, L E.J. [UKAEA, Harwell. Atomic Energy Research Establishment

1979-01-01

The subject is covered in sections as follows: general introduction (volume of waste arising from 1 GW/(e) energy per year); characteristics of highly active waste (output of some important fission products from an AGR, decay of activity with time for PWR and CFR wastes, toxic potential versus time for magnox and fast reactor wastes, toxic potential of unreprocessed magnox fuel); general principles of waste disposal (incorporation of waste into solid matrices, glass containers); design of stores and repositories (heat dissipation, siting and design, packing materials, size of repositories); the geologic barrier (location of repositories, safety analysis of repositories); the option of ocean disposal; status of work and present programme (vitrification, repository siting and design); conclusions.

Cast iron transport, storage and disposal containers for use in UK nuclear licensed sites - 59412

International Nuclear Information System (INIS)

Viermann, Joerg; Messer, Matthias P.

2012-01-01

Document available in abstract form only. Full text of publication follows: Ductile Cast Iron Containers of the types GCVI (UK trademark -GNS YELLOW BOX R ) and MOSAIK R have been in use in Germany for transport, storage and disposal of intermediate level radioactive waste (ILW) for more than two decades. In 2009 a number of containers of these types were delivered to various Magnox sites as so called pathfinders to test their suitability for Magnox waste streams. The results were encouraging. Therefore the Letter of Compliance (LoC) procedure was started to prove the suitability of packages using these types of containers for the future UK Geological Disposal Facility (GDF) and a conceptual Letter of Compliance (cLoC) was obtained from RWMD in 2010. Waste stream specific applications for Interim Stage Letters of Compliance (ILoC) for a number of waste streams from different Magnox sites and from the UK's only pressurised water reactor, Sizewell B are currently being prepared and discussed with RWMD. In order to achieve a package suitable for interim storage and disposal the contents of a Ductile Cast Iron Container only has to be dried. Mobile drying facilities are readily available. Containers and drying facilities form a concerted system

An investigation into the sealing of magnesium alloy cans by argon-arc welding

Energy Technology Data Exchange (ETDEWEB)

Taylor, A.F.

1964-05-15

The weldability of several magnesium alloys, which may be suitable as canning materials has been investigated. The most suitable welding conditions necessary for sealing Magnox C cans are recommended.

Nuclear power

International Nuclear Information System (INIS)

1987-01-01

''Nuclear Power'' describes how a reactor works and examines the different designs including Magnox, AGR, RBMK and PWR. It charts the growth of nuclear generation in the world and its contributions to world energy resources. (author)

Alien shores

International Nuclear Information System (INIS)

Viermann, Joerg

2014-01-01

The UK nuclear programme started out in the 1950's with some remarkable milestones: Calder Hall 1 was the first commercial reactor worldwide to be erected and was connected to the grid in 1956 with the other three Calder Hall Magnox reactors soon to follow. More Magnox reactors were built along the British coast in the 1950's and 60's. In 1971 the two reactors at Wylfa were the last UK Magnox reactors to be connected to the grid. Low level radioactive waste arising from electricity production went to the Drigg burial site, spent fuel to the Sellafield reprocessing facilities. Intermediate level waste was collected mainly on site, but also in the storage pools at Sellafield. This legacy now has to be dealt with. The UK's only PWR is operated by EDF Energy in Sizewell near Leiston which was connected to the grid in 1995. ILW resins have been collected over its first 18 years of operation. With the storage tanks running out of capacity within the following 2 years it was necessary to start filling these resins into waste containers, ideally into containers suitable for the planned UK repository. German expertise and experience in dealing with different types of ILW can be of benefit for UK operators. GNS products and services ideally match some of the actual challenges which GNS could prove in some initial waste processing projects. GNS also started to develop custom made solutions for the UK market.

Preliminary assessment of modified borosilicate glasses for chromium and ruthenium immobilization

Energy Technology Data Exchange (ETDEWEB)

Farid, Osama M. [Reactors Department, Nuclear Research Center, Atomic Energy Authority of Egypt, P.O. 13759, Inshas, Cairo (Egypt); Centre of Nuclear Engineering (CNE), Department of Materials, Imperial College London, London, SW7 2BP (United Kingdom); Abdel Rahman, R.O., E-mail: alaarehab@yahoo.com [Hot Laboratory Center, Atomic Energy Authority of Egypt, P.O. 13759, Inshas, Cairo (Egypt)

2017-01-15

The feasibility of using modified alkali borosilicate glasses for ruthenium and chromium immobilization is preliminary assessed by investigating the immobilization system structure under normal conditions. Within this context, reference alkali borosilicate, and simulated Magnox-modified glasses were prepared and studied. The results indicate that ruthenium is immobilized in the vitreous structure as encapsulated RuO{sub 2} crystallites that act as seeds for heterogeneous nucleation of other crystalline phases. The presence of Zn, as modifier, has contributed to chromium immobilization in zincochromite spinel structure, whereas Ca is accommodated in the vitreous structure. Immobilization performance was evaluated by conducting conservative static leach test and studying the leached glass. Leached glass morphology was altered, where near surface reference glass is leached over 400 nm and simulated Magnox-modified sample is altered over 300 nm. Normalized release rates are within normal range for borosilicate material. For simulated Magnox-modified sample, Ca and alkali structural element, i.e. Na and Li, are leached via ion-exchange reaction. The ion-exchanged fraction equals 1.06 × 10{sup −8} mol/m{sup 2} s and chromium has slightly lower normalized release rate value than ruthenium. - Highlights: • The presence of modifiers and waste oxides led to localized de-vitrification. • Ruthenium is encapsulated within the vitreous glass network as RuO{sub 2} crystals. • Chromium is immobilized within the zincochromite spinel structure. • Pitting and cracks induced by leaching did not affect the immobilization performance.

An investigation into the use of a fast breeder reactor to incinerate actinide waste from the U.K. nuclear power programme

International Nuclear Information System (INIS)

Harte, G.A.; Clarke, R.H.

1976-12-01

Preliminary investigations are described into the effect of actinide removal and incineration (i.e. re-irradiation in a high neutron flux) on the long term hazards of reprocessing wastes from a Magnox reactor and from a notional CFR operated on plutonium from a Magnox reactor and also from an AGR. The actinides neptunium, americium and curium extracted from these wastes would be amenable to incineration in a fast breeder reactor core with fluxes of the order of 10 16 ncm -2 s -1 . An incineration period of 35 years was found to achieve a reduction in hazard, for most cooling periods up to one million years. The reductions were 2 to 3 orders of magnitude for the Magnox wastes and 4 orders of magnitude for the waste from CFR fuelled with AGR-plutonium. The large reduction factors do not apply to the hazards of reprocessing wastes as a whole, however, since one actinide separation has been achieved the residual quantities of uranium and plutonium in the waste stream, assumed here to be 0.1% of the original fuel inventory of these elements, become dominant in determining the hazard. Shorter incineration periods may serve to reduce the hazards of the extracted transuranics below the levels determined by these residues. A discussion of the hazards associated with reprocessing wastes as compared to those associated with uranium mill tailings attempts to place the nuclear waste disposal problem in perspective. (author)

Scottish Nuclear, the company

International Nuclear Information System (INIS)

Yeomans, R.M.

1991-01-01

A former chief executive of Scottish Nuclear, formed when United Kingdom electricity generation was privatized, describes the financial viability of the company and considers the future of nuclear power. Scottish Nuclear owns and operates the Advanced Gas Cooled (AGR) and Magnox reactors at Hunterston and the AGR reactor at Torness and is a separate company from those dealing with hydro-electric and non-nuclear generation of electricity. Costs of running the reactors is identified as a proportion of the whole for certain key issues such as station costs, depreciation, decommissioning and insurance. While nuclear power generation using outmoded Magnox reactors is costly, the ecological cost of global warming is seen as more of a problem. Future policy for nuclear power in Scotland must include new plant, probably pressurized water reactors and a clear policy of safety enhancement. (UK)

Recent developments in simulator-based operator training in the UK

International Nuclear Information System (INIS)

Madden, V.J.

1987-01-01

Ever since the earliest days of the Magnox stations with training programs which were first run in the late 1950s, use has been made of simulation devices. In those early days of nuclear power, analog techniques were used to develop an understanding of reactor dynamics. The value of this type of limited scope device for training in basic principles has been confirmed over the years. The analog simulator - in use for over 20 years -has just been replaced by a microprocessor driven unit with extended scope to include a heat exchanger unit (thus completing the primary circuit). A wider range of faults have been incorporated together with tutor facilities and display systems which have taken advantage of today's technologies. The modelling software and the use of an interchangeable panel enable it to represent either a Magnox or an AGR system

Stainless steel fabrications: past and present

International Nuclear Information System (INIS)

Daniels, R.

1986-01-01

The paper deals with stainless steel fabrications of Fairey Engineering Company for the nuclear industry. The manufacture of stainless steel containers for Magnox and Advanced Gas Cooled Reactors, flexible fabrication facility, and welding development, are all briefly described. (U.K.)

Advanced gas-cooled reactors (AGR)

Energy Technology Data Exchange (ETDEWEB)

Yeomans, R. M. [South of Scotland Electricity Board, Hunterston Power Station, West Kilbride, Ayshire, UK

1981-01-15

The paper describes the advanced gas-cooled reactor system, Hunterston ''B'' power station, which is a development of the earlier natural uranium Magnox type reactor. Data of construction, capital cost, operating performance, reactor safety and also the list of future developments are given.

The relevance of crack arrest phenomena for pressure vessel structural integrity assessment

International Nuclear Information System (INIS)

Connors, D.C.; Dowling, A.R.; Flewitt, P.E.J.

1996-01-01

The potential role of a crack arrest argument for the structural integrity assessments of steel pressure vessels and the relationship between crack initiation and crack arrest philosophies are described. A typical structural integrity assessment using crack initiation fracture mechanics is illustrated by means of a case study based on assessment of the steel pressure vessels for Magnox power stations. Evidence of the occurrence of crack arrest in structures is presented and reviewed, and the applications to pressure vessels which are subjected to similar conditions are considered. An outline is given of the material characterisation that would be required to undertake a crack arrest integrity assessment. It is concluded that crack arrest arguments could be significant in the structural integrity assessment of PWR reactor pressure vessels under thermal shock conditions, whereas for Magnox steel pressure vessels it would be limited in its potential to supporting existing arguments. (author)

NUMEL: a computer aided design suite for the assessment of the steady state, static/dynamic stability and transient responses of nuclear steam generators

International Nuclear Information System (INIS)

Rowe, D.; Lightfoot, P.

1988-02-01

NUMEL is a computer aided design suite for the assessment of the steady state, static/dynamic stability and transient responses of nuclear steam generators. The equations solved are those of a monotube coflow or counterflow heat exchanger. The advantages of NUMEL are its fast execution speed, robustness, extensive validation and flexibility coupled with ease of use. The code can simultaneously model up to four separate sections (e.g. reheater, HP boiler). This document is a user manual and describes in detail the running of the NUMEL suite. In addition, a discussion is presented of the necessary approximations involved in representing a serpentine or helical AGR boiler as a monotube counterflow heat exchanger. To date, NUMEL has been applied to the modelling of AGR, Fast Reactor and once through Magnox and conventional boilers. Other versions of the code are available for specialist applications, e.g. Magnox and conventional recirculation boilers. (author)

Italian experience on the processing of solid radioactive wastes

International Nuclear Information System (INIS)

Costa, A.; De Angelis, G.

1989-12-01

Experimental work is under way in Italy for treatment and conditioning of different types of solid radioactive wastes. The following wastes are taken into account in this paper: Magnox fuel element debris, solid compactable wastes, radiation sources and contaminated carcasses. The metallic debris, consisting of Magnox splitters and braces, are conditioned, after drying and separation of corrosion products, by means of a two component epoxy system (base product + hardener). Solid compactable wastes are reduced in volume by using a press. The resulting pellets are transferred to a final container and conditioned with a cement mortar of a suitable consistency. As to the radiation sources, mainly contained in lightning-rods, gas detectors and radioactive thickness gauges, the encapsulation in a cementitious grout is a common practice for their incorporation. Early experiments, with satisfactory results, have also been conducted for the cementation of contaminated carcasses. (author)

Degradation of building materials over a lifespan of 30-100 years

International Nuclear Information System (INIS)

Lewis, G.H.

1985-01-01

Following preliminary visits to four Magnox Nuclear Power Stations, a study was made of existing Central Electricity Generating Board (CEGB) reports on the condition of buildings at eight Power Stations. Sampling of building materials, non-destructive testing and inspections were carried out at Transfynydd, Oldbury and Dungeness ''A'' Magnox Power Stations, and the samples were subsequently laboratory tested. From the results of this work it can be concluded that little major deterioration is likely to occur in the reactor buildings at Transfynydd and Oldbury over the next 50 years and at Dungeness ''A'' for at least 25 years, assuming reasonable maintenance and the continuation of suitable internal temperatures and relative humidities. Because of the limitations on taking samples from, and tests on, the reactor biological shields and prestressed concrete vessel, no sensible forecast can be made of their potential life in the 75-100 year range

Radiolytic graphite oxidation revisited

International Nuclear Information System (INIS)

Minshall, P.C.; Sadler, I.A.; Wickham, A.J.

1996-01-01

The importance of radiolytic oxidation in graphite-moderated CO 2 -cooled reactors has long been recognised, especially in the Advanced Gas-Cooled Reactors where potential rates are higher because of the higher gas pressure and ratings than the earlier Magnox designs. In all such reactors, the rate of oxidation is partly inhibited by the CO produced in the reaction and, in the AGR, further reduced by the deliberate addition of CH 4 . Significant roles are also played by H 2 and H 2 O. This paper reviews briefly the mechanisms of these processes and the data on which they are based. However, operational experience has demonstrated that these basic principles are unsatisfactory in a number of respects. Gilsocarbon graphites produced by different manufacturers have demonstrated a significant difference in oxidation rate despite a similar specification and apparent equivalence in their pore size and distribution, considered to be the dominant influence on oxidation rate for a given coolant-gas composition. Separately, the inhibiting influence of CH 4 , which for many years had been considered to arise from the formation of a sacrificial deposit on the pore walls, cannot adequately be explained by the actual quantities of such deposits found in monitoring samples which frequently contain far less deposited carbon than do samples from Magnox reactors where the only source of such deposits is the CO. The paper also describes the current status of moderator weight-loss predictions for Magnox and AGR Moderators and the validation of the POGO and DIFFUSE6 codes respectively. 2 refs, 5 figs

Key differentiators influencing the choice of robust shielded containers

Energy Technology Data Exchange (ETDEWEB)

Morris, Jenny; Wickham, Stephen [Galson Sciences Limited Oakham, Rutland (United Kingdom); Nicholls, David [AREVA Risk Management Consulting Abingdon, Oxfordshire (United Kingdom); Walsh, Ciara [NDA RWMD, Harwell, Oxfordshire (United Kingdom); McKinney, James [NDA Moor Row, Cumbria (United Kingdom)

2013-07-01

The NDA's Upstream Optioneering project has examined the potential implications of using an alternative type of waste package and its influence on the waste management lifecycle across the NDA estate. Robust Shielded Containers (RSCs) are radioactive waste packages that provide integral radiological shielding, reducing the need for remote handling. The robustness of the container could remove the need to immobilise waste by cement encapsulation. RSCs are routinely used to package ILW for interim storage in Germany and have fairly recently been considered for use in the UK because RSCs have the potential to simplify the waste management lifecycle and enable risk and hazard reduction. In particular, the current baseline (included in Magnox Limited lifetime plans) follows the strategy set out in the Magnox Operating Decommissioning Programme (MODP), in which Type II MOSAIK and Type VI Ductile Cast Iron Containers (DCICs) are used to package (in non-encapsulated form) most Magnox ILW arising prior to 2050. By considering representative types of Intermediate Level Waste (ILW) and exploring potential packaging options for these wastes, this paper identifies the factors that could differentiate between cases in which RSCs would, or would not, be an appropriate option. The potential role of RSCs across the waste management lifecycle is examined, from retrieval of waste through to emplacement at a Geological Disposal Facility (GDF), including consideration of other potential uses of RSCs, such as temporary storage of raw wastes for which appropriate treatment and conditioning measures have yet to be developed. (authors)

Fabrication of electroslag welded Magnox fuel transport flasks

International Nuclear Information System (INIS)

Tuliani, S.S.

1979-01-01

The high weld metal deposition rate of the electroslag welding process offers an attractive method of fabricating nuclear fuel transport flasks from 370 mm (14.5in) thick steel plates. The paper describes pre-production trials carried out on full scale corner-section joints to establish that the weld metal meets the exacting mechanical property requirements for the Nuclear Industry. The paper presents results obtained on welds produced using two base metal compositions and two wires, one recommended for submerged-arc and the other for electroslag welding processes. Details of mechanical tests and metallographic examinations are given which led to the selection of the latter type of wire. It was found that while the weld metal deposited by this process may be sensitive to cracking, this can be avoided by careful selection of welding consumables and sound joints can be obtained under production conditions. (author)

Nuclear Energy

International Nuclear Information System (INIS)

1982-11-01

A brief indication is given of the United Kingdom nuclear power programme including descriptions of the fission process, the Magnox, AGR and PWR type reactors, the recycling process, waste management and decommissioning, safety precautions, the prototype fast reactor at Dounreay, and the JET fusion experiment. (U.K.)

The development and implementation of a waste management strategy

International Nuclear Information System (INIS)

Fairhall, G.A.; Vickery, P.; Edmiston, L.

1999-01-01

Over the past forty years BNFL has operated 4 nuclear sites in the UK. Commercial operations on these sites span the full nuclear fuel cycle from enrichment, fuel fabrication, electricity generation, reprocessing, waste management, and decommissioning. Through the recent merger with Magnox Electric BNFL has acquired a further 8 Magnox reactor sites in the UK. Prior to 1980 BNFL adopted a policy of storing wastes generated by its activities in an unconditioned state in purpose built stores. This paper shows how BNFL's waste management strategy has developed to ensure how volume reduction technologies have been implemented for low level waste. Whilst immobilisation technologies have been implemented for high and intermediate level wastes. The paper describes how continual review of the strategy ensures waste management processes are continually monitored against progress and optimised to ensure all waste arisings are conditioned for final disposal. Finally the paper will show how the strategy can be used to develop waste management plans for customer sites. (author)

The seismic assessment of radially keyed graphite moderator cores

International Nuclear Information System (INIS)

Steer, A.G.; Payne, J.F.B.

1996-01-01

The modelling of AGR and Magnox cores has to deal with the very large number of components that make up the core, and the non-linear response due to the clearances in the keying system. This paper examines the conditions under which it is permissible to linearise the response. By comparing the results of discrete and continuum models of the core, the paper also shows that the number of components in the core is sufficiently large that the core can be approximated satisfactorily by an anisotropic solid material. The material has unusual properties, but these can be handled within the standard framework for the description of the elastic properties of an anisotropic solid. This description of the core by an equivalent solid material can readily be incorporated into finite element models of the reactor internal structure. Such models have been set up for both AGR and Magnox reactors. The models are being used to assess the seismic response of these reactors. (author). 5 refs, 6 figs

Keeping reactors on the road

International Nuclear Information System (INIS)

Anon.

1980-01-01

A description of the repair package developed by Marchwood Engineering Laboratories used for remotely reinforcing thermocouple support tubes at the Oldbury Magnox station is given. A system giving improved access to constrained areas by sterophotography is briefly discussed. The use of holography as an inspection tool is also outlined. (author)

Radionuclide compositions of spent fuel and high level waste from commercial nuclear reactors

International Nuclear Information System (INIS)

Goodill, D.R.; Tymons, B.J.

1984-10-01

This report provides information on radionuclide compositions of spent fuel and high level waste produced during reprocessing. The reactor types considered are Magnox, AGR, PWR and CFR. The activities of the radionuclides are calculated using the FISPIN code. The results are presented in a form suitable for radioactive waste management calculations. (author)

Main conclusions of a seminar on managing technical resources in a changing nuclear industry

International Nuclear Information System (INIS)

Storey, P.D.

2000-01-01

The author recapitulates the different points from I Mech E Conference (Managing Technical resources in a changing Nuclear Industry -London, 29 September 1999), as following: UK position, BNFL Magnox and AEAT, UK view from BEGL, view from WANO, UK view from UKAEA, USA view from PECO Energy, and view from OECD NEA

The effect on design of ISI

International Nuclear Information System (INIS)

Hart, J.D.

The evolution of in-service inspection techniques from the Magnox reactors through the AGR constructions is described. The following aspects are mentioned: general principles; factors that have influenced the development of ISI; objectives of ISI; examples drawn from AGR experience; major design changes to accommodate ISI; PWR reactors; occupational safety. (U.K.)

The development of direct core monitoring in Nuclear Electric plc

International Nuclear Information System (INIS)

Curtis, R.F.; Jones, S. Reed, J.; Wickham, A.J.

1996-01-01

Monitoring of graphite behaviour in Nuclear Electric Magnox and AGR reactors is necessary to support operating safety cases and to ensure that reactor operation is optimized to sustain the necessary core integrity for the economic life of the reactors. The monitoring programme combines studies for pre-characterized ''installed'' samples with studies on samples trepanned from within the cores and also with studies of core and channel geometry using specially designed equipment. Nuclear Electric has two trepanning machines originally designed for Magnox-reactor work which have been used for a substantial programme over many years. They have recently been upgraded to improve sampling speed, safety and versatility - the last being demonstrated by their adaptation for a recently-won contract associated with decommissioning the Windscale piles. Radiological hazards perceived when the AGR trepanning system was designed resulted in very cumbersome equipment. This has worked well but has been inconvenient in operation. The development of a smaller and improved system for deploying the equipment is now reported. Channel dimension monitoring equipment is discussed in detail with examples of data recovered from both Magnox and AGR cores. A resolution of ± 2 of arc (tilt) and ± 0.01 mm change in diameter in attainable. It is also theoretically possible to establish brick stresses by measuring geometry changes which result from trepanning. Current development work on a revolving scanning laser rangefinder which will enable the measurement of diameters to a resolution of 0.001 mm will also be discussed. This paper also discusses non-destructive techniques for crack detection employing ultrasound or resistance networks, the use of special manipulators to deliver inspection and repair equipment and recent developments to install displacement monitors in peripheral regions of the cores, to aid the understanding of the interaction of the restraint system with the core - the region

Steam generator materials constraints in UK design gas-cooled reactors

International Nuclear Information System (INIS)

James, D.W.

1988-01-01

A widely reported problem with Magnox-type reactors was the oxidation of carbon steel components in gas circuits and steam generators. The effects of temperature, pressure, gas composition and steel composition on oxidation kinetics have been determined, thus allowing the probabilities of failure of critical components to be predicted for a given set of operating conditions. This risk analysis, coupled with regular inspection of reactor and boiler internals, has allowed continued operation of all U.K. Magnox plant. The Advanced Gas Cooled Reactor (AGR) is a direct development of the Magnox design. The first four AGRs commenced operation in 1976, at Hinkley Point 'B' and at Hunterston 'B'. All known materials problems with the steam generators have been diagnosed and solved by the development of appropriate operational strategies, together with minor plant modifications. Materials constraints no longer impose any restrictions to full load performance from the steam generators throughout the predicted life of the plant. Problems discussed in detail are: 1. oxidation of the 9 Cr - 1 Mo superheater. 2. Stress corrosion of the austenitic superheater. 3. Creep of the transition joints between the 9 Cr - 1 Mo and austenitic sections. With the 9 Cr - 1 Mo oxidation maximum temperature restriction virtually removed and creep constraints properly quantified, boiler operation in now favourably placed. Stress corrosion research has allowed the risk of tube failure to be related to time, temperature, stress and chemistry. As a result, the rigorous 'no wetting' policy has been relaxed for the normally high quality AGR feedwater, and the superheat margin has been reduced to 23 deg. C. This has increased the size of the operating window and reduced the number of expensive, and potentially harmful, plant trips. (author)

The use of scale models in impact testing

International Nuclear Information System (INIS)

Donelan, P.J.; Dowling, A.R.

1985-01-01

Theoretical analysis, component testing and model flask testing are employed to investigate the validity of scale models for demonstrating the behaviour of Magnox flasks under impact conditions. Model testing is shown to be a powerful and convenient tool provided adequate care is taken with detail design and manufacture of models and with experimental control. (author)

A UK perspective on recycling

International Nuclear Information System (INIS)

Williams, T.

1991-01-01

The United Kingdom, through the recycling of depleted uranium from Magnox reactors into Advanced Gas-cooled Reactor (AGR) fuel, has already recycled significant quantities of reprocessed material in reactors owned by Nuclear Electric plc and Scottish Nuclear Limited. This AGR fuel has been satisfactorily irradiated and discharged over a decade or more, and will be reprocessed in the new Thermal Oxide Reprocessing Plant (THORP), currently under construction in the UK. British Nuclear Fuels plc (BNFL) and the UK Atomic Energy Authority (UKAEA) have also been exploiting the potential of plutonium recycled in mixed oxide (MOX) fuel, which they have been making since 1963. All of the UK nuclear companies are committed to further recycling of Magnox depleted uranium during the 1990s, and it is anticipated that oxide recycling will also become firmly established during the next decade. British Nuclear Fuels and Urenco Ltd, as the providers of fuel cycle services, are developing an infrastructure to close the fuel cycle for oxide nuclear fuel, using both the uranium and plutonium arising from reprocessing. (author)

Analysis and study of spent fuel reprocessing technology from birth to present

International Nuclear Information System (INIS)

Takahashi, Keizo

2006-01-01

As for the nuclear fuel reprocessing of the spent fuel, although there was argument of pros and cons, it was decided to start Rokkasho reprocessing project further at the Japan Atomic Energy Commission of ''Long-Term Program for Research, Development and Utilization of Nuclear Energy'' in year 2004. The operation of Tokai Reprocessing is going steadily to reprocess spent fuel more than 1,100 tons. In this paper, history, present status and future of reprocessing technology is discussed focusing from military Pu production, Magnox fuel reprocessing to oxide fuel reprocessing. Amount of reprocessed fuel are estimated based on fuel type. Then, history of reprocessing, US, UK, France, Germany, Russian, Belgian and Japan is presented and compared on technology, national character, development organization, environmental protection, and high active waste vitrification. Technical requirements are increased from Pu production fuel, Magnox fuel and oxide fuel mainly because of higher burnup. Reprocessing technology is synthetic of engineering and accumulation of operational experience. The lessons learned from the operational experience of the world will be helpful for establishment of nuclear fuel reprocessing technology in Japan. (author)

Report and accounts 1989/90

International Nuclear Information System (INIS)

1991-01-01

Nuclear Electric was set up to run all the Magnox and AGR nuclear power stations and nuclear-related assets of the Central Electricity Generating Board. It is also to be responsible for the construction and operation of the PWR station at Sizewell-B in Suffolk. The decision not to privatise the nuclear section of the electricity supply industry in England but to retain it in government ownership came quite late on so the handover to Nuclear Electric was set up in 20 weeks, so that the new company could start operating on 31st march 1990. This report sets out the first year's progress and reviews the operation of the Magnox and AGR reactors and the construction of Sizewell-B including a revised cost estimation. Health and Safety is an important objective of the company and its committment to this and to environmental protection is stated. The Directors Report and company accounts presented. The accounts show an operating profit but an overall loss for the financial year 1989/90. (UK)

Nuclear reactor types

International Nuclear Information System (INIS)

Jones, P.M.S.

1987-01-01

The characteristics of different reactor types designed to exploit controlled fission reactions are explained. Reactors vary from low power research devices to high power devices especially designed to produce heat, either for direct use or to produce steam to drive turbines to generate electricity or propel ships. A general outline of basic reactors (thermal and fast) is given and then the different designs considered. The first are gas cooled, including the Magnox reactors (a list of UK Magnox stations and reactor performance is given), advanced gas cooled reactors (a list of UK AGRs is given) and the high temperature reactor. Light water cooled reactors (pressurized water [PWR] and boiling water [BWR] reactors) are considered next. Heavy water reactors are explained and listed. The pressurized heavy water reactors (including CANDU type reactors), boiling light water, steam generating heavy water reactors and gas cooled heavy water reactors all come into this category. Fast reactors (liquid metal fast breeder reactors and gas cooled fast reactors) and then water-cooled graphite-moderated reactors (RBMK) (the type at Chernobyl-4) are discussed. (U.K.)

Nuclear power reactors

International Nuclear Information System (INIS)

1982-11-01

After an introduction and general explanation of nuclear power the following reactor types are described: magnox thermal reactor; advanced gas-cooled reactor (AGR); pressurised water reactor (PWR); fast reactors (sodium cooled); boiling water reactor (BWR); CANDU thermal reactor; steam generating heavy water reactor (SGHWR); high temperature reactor (HTR); Leningrad (RMBK) type water-cooled graphite moderated reactor. (U.K.)

Thermal reactor strategy

International Nuclear Information System (INIS)

1981-01-01

This statement sets down briefly the CEGB's views on the requirement for nuclear power and outlines current progress in the implementation of the CEGB's thermal reactor strategy. The programme is traced historically, together with statements of Government policy. The place of Magnox, AGR, SGHWR, PWR and fast breeder reactors is discussed. Advantages and problems associated with the various types are outlined. (U.K.)

The politics of fading dreams: Britain and the nuclear export business

International Nuclear Information System (INIS)

Boardman, R.; Grieve, M.

1983-01-01

The subject is discussed as follows: introduction to a chapter focused on the politics of Britain's foreign nuclear trade; export goals and the nuclear programme (discussion of Magnox, AGR, SGHWR and PWR); the pursuit of exports; nuclear exports and proliferation (reprocessing; fast reactors; plutonium; INFCE); public opinion, nuclear power and exports (interest groups); conclusions (Britain's nuclear exports and non-proliferation). (U.K.)

A preliminary redrafting of the Italian technical guide no.26 on radioactive waste management

International Nuclear Information System (INIS)

Tocci, M.

1993-01-01

The recent National Energy Plan confirms the need for reprocessing of the nuclear spent fuel arising from the Nuclear Power Plants (NPPs) that were definitively put out of operation after Chernobyl accident. Two campaigns concerning the Italian spent fuel reprocessing are starting at this time. The first-one is related to LATINA (MAGNOX, GCR 160 MWe) while the second one will concern GARIGLIANO (BWR 160 MWe), CAORSO (BWR 840 MWe) and TRINO (PWR, 200 MWe). The first campaign will involve about 600 tons of MAGNOX spent fuel arising from LATINA NPP which will be reprocessed in the next future by BNFL (British Nuclear Fuel Limited) at Sellafield. The vitrified High Level Wastes (HLW) shall return to Italy starting from 1994. ENEA-DISP (Italian directorate for Nuclear Safety) has received from BNFL the technical specifications of the glass blocks. The approval of those specifications is scheduled by the end of 1993, in order to allow the delivery of the wastes. During the licensing iter ENEA-DISP will use its own Technical Guide N. 26, which identifies and specifies the basic criteria and requirements for an appropriate waste management policy. (author). 4 figs., 5 refs

A study of explosive demolition techniques for heavy reinforced and prestressed concrete structures

International Nuclear Information System (INIS)

Fleischer, C.C.

1984-10-01

This report presents the results from a research programme aimed at advancing explosive demolition techniques from the present 'rule of thumb art' to a more scientifically based set of procedures to achieve the degree of control which will be essential in a nuclear power station decommissioning. The research is directed mainly at the biological shields of early Magnox reactors and the prestressed concrete pressure vessels (PCPVs) of later Magnox and Advanced Gas-cooled reactors. Relevant structures of other commercial nuclear power plants in the European Community, in particular the PCPVs of French Gas Graphite reactors and the biological shields of Light Water reactors are also considered. The bulk of the programme has been based on experiments with an extensive usage of scaled models. The programme investigated the use of buried explosive charges in cratering concrete and the use of shaped charges in stripping surface cover and drilling holes. After an initial parametric study the programme considered concrete layer stripping using multiple charges and culminated in the stripping off of an equivalent thickness of concrete, for radiation protection, from the inside walls of a complete cylindrical model of a biological shield. (author)

A study of explosive demolition techniques for heavy reinforced and prestressed concrete structures

International Nuclear Information System (INIS)

Fleischer, C.C.

1985-01-01

This report presents the results from a research programme aimed at advancing explosive demolition techniques from the present ''rule of thumb art'' to a more scientifically based set of procedures to achieve the degree of control which will be essential in a nuclear power station decommissioning. The research is directed mainly at the biological shields of early Magnox reactors and the prestressed concrete pressure vessels (PCPVs) of later Magnox and advanced gas-cooled reactors. Relevant structures of other commercial nuclear power plants in the European Community, in particular the PCPVs of French gas graphite reactors and the biological shields of light water reactors are also considered. The bulk of the programme has been based on experiments with an extensive usage of scaled models. The programme investigated the use of buried explosive charges in cratering concrete and the use of shaped charges in stripping surface cover and drilling holes. After an initial parametric study the programme considered concrete layer stripping using multiple charges and culminated in the stripping off of an equivalent thickness of concrete, for radiation protection, from the inside walls of a complete cylindrical model of a biological shield

Dungeness 'A' Nuclear Power Station. The findings of NII's assessment of Nuclear Electric's long term safety review

International Nuclear Information System (INIS)

1994-01-01

The assessment is reported of Nuclear Electrics' Long Term Safety Reviews (LTSR) of the Dungeness A magnox reactors. The assessment was undertaken by the Health and Safety Executive's Nuclear Installations Inspectorate (NII) which is responsible for regulating the safety of nuclear installations in the United Kingdom. This was one of a programme of LTSRs for all the UK magnox reactors. The LTSR for each plant was proceeded by a Generic Issues programme. The results of both the LTSR and the Generic Issues programme have been used by NII in forming the conclusions of this assessment. Overall the safety case for Dungeness A is satisfactory for continued operation. A programme of additional modifications and inspections has been put in place which further enhances the safety justification. Reactor operations will continue to be monitored and regulated in accordance with the inspections required under the licensing arrangements. Provided these requirements and the agreed further analysis, improvements and inspections give satisfactory results it is expected that the station will be able to operate safely till each reactor is at least 30 years old. Beyond this point a further Periodic Safety Review will be required. (UK)

Economies of scale in electricity generation and transmission since 1945

International Nuclear Information System (INIS)

Tombs, F.

1978-01-01

Progress in the electricity supply industry since 1945 is reviewed with particular reference to increased ratings of plant and transmission. The contribution of nuclear energy is emphasised. Developments which have taken place, and policy within the nuclear industry since the construction of Calder Hall, are examined. The performance of the Magnox stations, difficulties with AGRs, and the debate on the choice of reactors are discussed. (U.K.)

'E minimis maxima' or The work of the UKAEA Laboratories at Windscale

International Nuclear Information System (INIS)

Lawton, H.

1983-01-01

The paper describes the work carried out at Windscale's reprocessing site for thermal reactor fuels. Thermal reactor fuel behaviour is discussed, with reference to Magnox fuel, AGR fuel and water fuel. Fuel work that has application to more than one reactor system is mentioned. The plutonium studies on the development of the mixed plutonium/uranium oxide fuel for use in fast reactors is also considered. (U.K.)

The role of equilibrium leach testing in understanding the behaviour of nuclear wastes under disposal conditions

International Nuclear Information System (INIS)

Biddle, P.; Rees, J.H.

1988-01-01

Results from the equilibrium leach testing of a range of intermediate level nuclear wastes have been modelled using sorption and solubility data obtained in experiments with individual radionuclides. The wastes involved were AGR hulls, Magnox cladding wastes, combustible plutonium-contaminated materials and ferric/aluminium hydroxide flocs. The test has an important role in validating near-field models, and helps to build confidence in disposal assessments. (author)

Magnesium microelectrode corrosion product transport modelling in relation to chloride induced pitting

International Nuclear Information System (INIS)

Burrows, R.; Cook, A.; Stevens, N.P.C.

2012-09-01

The high magnesium alloy Magnox is used as a fuel clad for the UK gas cooled, graphite moderated reactors of the same name. The fuel is metallic uranium (typically natural enrichment), so a low neutron absorption cross-section clad is required. Following discharge from reactor, spent fuel is stored in water, which acts as an effective heat transfer medium and biological shield. The chemistry of these ponds is carefully controlled to ensure that the Magnox clad remains in a passive state. This is primarily through the maintenance of a high pH and very low anion concentration. Of particular concern is the presence of chloride ions as even very low levels may allow localised corrosion to initiate. Although extensive work has been undertaken historically considering the behaviour of Magnox clad and the acceptable storage envelopes, the challenges of ageing plant and aspirations for accelerated decommissioning give value to further understanding of the corrosion mechanisms of this material. Recently, electrochemical techniques have been employed to characterise performance in a variety of chemistries and microelectrodes have been produced which have shown characteristics of salt film corrosion at moderate chloride concentrations under polarisation. A characteristic of the electrochemical response observed during the mass transport limited (potential independent) salt film regime has been periodic transients which correspond to emission of microscopic hydrogen bubbles from the microelectrode cavity. A simple finite element multi-physics model has been employed to assist in understanding the dominant processes of corrosion product transport away from a magnesium electrode surface which is dissolving under a salt film and this shows that characteristic transients observed in electrochemical tests may be simulated with reasonable agreement by consideration of convection from laminar flow around hydrogen micro-bubbles in the pit cavity combined with aqueous diffusion in the

A review of the rates of reaction of unirradiated uranium in gaseous atmospheres

International Nuclear Information System (INIS)

Pearce, R.J.

1989-10-01

The review collates available quantitative rate data for the reaction of unirradiated uranium in dry and moist air, steam and carbon dioxide based atmospheres at temperatures ranging from room temperature to above the melting point of uranium. Reactions in nitrogen and carbon monoxide are also considered. The aim of the review is to provide a compilation of base data for the hazard analysis of fault conditions relating to Magnox fuel. (author)

The CEGB/SSEB response to Recommendation 18 in the Environment Committee's Report on Radioactive Waste

International Nuclear Information System (INIS)

1986-12-01

This report assesses the potential for the direct disposal of Magnox fuel which has previously been stored under dry conditions. It examines what, if any, processing the fuel may require prior to encapsulation, how encapsulation should be performed, the applicability of the existing multi-barrier concept for the disposal of spent oxide fuel and other relevant wastes, and whether the objectives for safe disposal can be attained. (author)

The reasons behind BNFL's corporate plan

International Nuclear Information System (INIS)

Holthorp, J.

1981-01-01

BNFL's Pound3000 million investment programme over the next ten years is described and explained. Major projects are the thermal oxide reprocessing plant (THORP), and renovation and improvement of the Magnox reprocessing plant and its associated highly active storage tanks. Other developments include a site ion exchange effluent plant (SIXEP), a vitrification plant, expansion of the centrifuge plant and upgrading of the fuel element fabrication facilities. (U.K.)

Preliminary studies on fabrication routes for SYNROC

International Nuclear Information System (INIS)

Evans, J.P.; Paige, E.L.

1980-12-01

The use of Synroc as a disposal medium for magnox waste has been evaluated and three possible methods of fabrication have been investigated. Hot pressing in graphite dies has produced the highest densities - further work is proceeding on sintering and hot isostatic pressing. The leach test results have indicated that the lowest density samples have adequate leach resistance while the higher density samples are an order of magnitude better. (author)

Environmental aspects of nuclear power

International Nuclear Information System (INIS)

Feates, F.

1981-01-01

The subject is discussed under the headings: background (scope of paper is a consideration of the radioactive by-products that arise from normal operation of nuclear power generating facilities; how regulated and their relative significance); legislation and regulation; the fuel cycle - fuel fabrication; use (of the fuel in the reactor; wastes from a typical CEGB Magnox power station); reprocessing (wastes from reprocessing); other wastes; disposal (including sea disposal). (U.K.)

Ultrasonic inspection of the Calder Hall and Chaplecross reactor pressure vessels

International Nuclear Information System (INIS)

Pennick, A.M.

1993-01-01

This paper describes the ultrasonic inspection surveys that have recently been carried out on the Calder Hall and Chapelcross Magnox steel reactor pressure vessels. The development of the inspection system, which is based on the Rediman manipulator and uses the Sonomatic Zipscan equipment and Time-of-Flight diffraction techniques is discussed. The inspection results are presented and compared with the original inspection findings and limiting crack sizes. (author)

Red alert. The worldwide dangers of nuclear power

Energy Technology Data Exchange (ETDEWEB)

Cook, J

1986-01-01

The book 'Red Alert' considers the problems and hazards of nuclear power. The politics behind the nuclear power programmes in the United Kingdom and other countries are examined, along with the sequence of events in Britain which led to the building of the Magnox and Advanced Gas-Cooled nuclear reactors. Health hazards of radiation, radioactive waste management, nuclear weapons programmes, and radiation accidents including the Chernobyl accident, are also discussed. (U.K.).

Tracked vehicles in hazardous environments

International Nuclear Information System (INIS)

Jones, S.; Walton, P.J.

1993-01-01

A programme of remote inspections has been conducted on the Magnox steel reactor pressure vessel at Trawsfynydd Power Station using climbing vehicles. Tracked remotely operated vehicles supported the inspection programme by assisting with the delivery and recovery of the climbing vehicles and facilitating the use of various accessory packages. This paper presents details of the support project, the tracked vehicles and of the uses made of them during the inspection programme. (author)

Annual report and accounts 1994/95: Scottish Nuclear

International Nuclear Information System (INIS)

1995-01-01

The Annual Report and Accounts for Scottish Nuclear are presented for the year 1994/1995. Scottish Nuclear Limited produces about half of Scotland's electricity requirement in its advanced gas-cooled reactors (AGRs) at Hunterston and Torness. It also has responsibility for decommissioning the Hunterston A Magnox nuclear power station. The role of the company in the international arena and as part of the United Kingdom's electric power industry, following privatisation, are discussed. (UK)

The testing of the in situ fire extinction system of the Trawsfynydd splitter debris storage package

International Nuclear Information System (INIS)

Newman, R.N.

1987-01-01

The proposed design of a Magnox splitter debris storage drum for Trawsfynydd incorporates an in situ solid fire extinguishant Graphex CK23 on the debris surface. This is an interlamellar graphite residue compound that intumesces when heated to provide an air-restricting layer. Two series of fire tests with the extinguishant in place have been carried out on full sized drums containing unirradiated splitter debris, to demonstrate the effectiveness of the system. (author)

Small-angle neutron-scattering experiments

International Nuclear Information System (INIS)

Hardy, A.D.; Thomas, M.W.; Rouse, K.D.

1981-04-01

A brief introduction to the technique of small-angle neutron scattering is given. The layout and operation of the small-angle scattering spectrometer, mounted on the AERE PLUTO reactor, is also described. Results obtained using the spectrometer are presented for three materials (doped uranium dioxide, Magnox cladding and nitrided steel) of interest to Springfields Nuclear Power Development Laboratories. The results obtained are discussed in relation to other known data for these materials. (author)

Safety Case for Safe-store

International Nuclear Information System (INIS)

Woollam, Paul B.

2002-01-01

Magnox Electric plc (Magnox), a wholly owned subsidiary of BNFL, owns 26 gas-cooled, graphite-moderated units on 11 sites in the UK. Eight units have been permanently shutdown and the remainder will shut this decade in a currently declared closure programme. The first of these reactors went to power in 1952 and the fleet has generated typically 9% of the UK's electricity during the last five decades. In accordance with UK Government policy, BNFL aims for a systematic and progressive reduction in hazards on its decommissioning sites. The end-point of the decommissioning process is that the reactors will be dismantled and their sites de-licensed. This will be done through minimising both the risks to the public, workers and the environment and also the lifetime cost, consistent with world class safety. There will be passive safe storage during deferment periods and it is BNFL's clear intent that the reactors will not be Safe-stored indefinitely. The main hazard associated with any decommissioned nuclear site is the spent fuel. Hence the reactors will be de-fuelled as soon as practicable after shutdown. After this work is complete, Cs-137 contaminated plant (e.g. fuel pools, effluent plant, and drains) will be dismantled when it is no longer needed. All other plant and buildings will also be dismantled when they are no longer needed, except for the reactor buildings which will be put into passive safe storage. Co-60 contaminated plant, such as steam generators, will be dismantled with the reactors. The reactors will be dismantled in a sequenced programme, with a notional start time around 100 years from shutdown. Magnox Electric is ensuring that the reactors and primary circuits on all its sites are well characterised. We have carried out a detailed, peer reviewed hazard identification on the lead site from which we have generated a rolling 25-year basic safety case. We have then searched for cliff edge effects and possible long-term changes to generate the 100-year

Britain's nuclear workhorses

International Nuclear Information System (INIS)

Hawkins, A.E.

1975-01-01

Britain's record in the field of nuclear power is briefly summarised. The success of the Magnox reactors is attributed to their reliability, good safety record, and the competitiveness of the fuel costs. The GR stations are expected to prove extremely valuable in spite of initial setbacks. In planning for future plant, it is suggested that the best way of utilizing the financial, human, and material resources required is by international collaboration on design and development. (U.K.)

Visit of the RPII to the Wylfa Nuclear Power Plant

International Nuclear Information System (INIS)

2007-08-01

This document is a report of the visit of RPII representatives to the Wylfa Nuclear Power Plant in Anglesey in North Wales. The principal topics covered are radioactive waste management, safety issues and the future of the Wylfa NPP. There was also a site tourwhich included the reactor building, the control room, the turbine hall and the simulator. Staff from Magnox Electric, which operates the Wylfa NPP, the NII and the UK Environment Agency participated in the visit

Direct-reading spectrochemical analysis of magnesium alloys

International Nuclear Information System (INIS)

Roca Adell, M.

1964-01-01

A Quantometer has been applied to the determination of aluminum, berylium, calcium, iron, silicon and zinc in magnesium alloys Magnox, after the conversion of the samples to the oxide. For the aluminum, whose concentration is relatively high, the conducting briquets technique with an interrupted discharge is employed, using the magnesium as the internal standard. For the other elements a total burning method with direct current arc is employed, using also the magnesium as the internal standard. (Author) 7 refs

Direct-reading spectrochemical analysis of magnesium alloys; Analisis espectroquimico de lectura directa de aleaciones de magnesio

Energy Technology Data Exchange (ETDEWEB)

Roca Adell, M

1964-07-01

A Quantometer has been applied to the determination of aluminum, berylium, calcium, iron, silicon and zinc in magnesium alloys Magnox, after the conversion of the samples to the oxide. For the aluminum, whose concentration is relatively high, the conducting briquets technique with an interrupted discharge is employed, using the magnesium as the internal standard. For the other elements a total burning method with direct current arc is employed, using also the magnesium as the internal standard. (Author) 7 refs.

Radioactive liquid waste discharged from Nuclear Electric licensed sites during 1991

International Nuclear Information System (INIS)

Austin, L.S.; Odell, K.J.

1993-03-01

This report presents the detailed isotopic composition of radioactive liquid waste discharged from Nuclear Electric licensed sites in 1991. Liquid discharges from those Magnox stations using pond storage of irradiated fuel contained low levels of activation and fission products, while those from Wylfa and the AGR stations contained lower levels of activation products with only traces of fission products. Discharges were similar to those observed in previous years, with any changes concordant with changes in stations' generation performance. (author)

Development and optimisation of generic decommissioning strategies for civil Magnox reactors

International Nuclear Information System (INIS)

Carpenter, G.; Hebditch, D.; Meek, N.; Patel, A.; Reeve, P.

2004-01-01

BNFL Environmental Services has formulated updated proposals for the use of decision analysis in the development of decommissioning strategy. The proposals are based on the Department of Transport, Local Government and the Regions manual for practitioners on multi-criteria analysis, specifically multi-criteria decision analysis, as suited to complex problems with a mixture of monetary and non-monetary objectives. They take account of up-to-date academic methodology, the newly issued BNFL decision analysis framework for environmental decisions and a wide variety of other engineering, optioneering and optimisation processes. The paper also summarises legislative and company policy areas of importance to decommissioning strategy development. Higher-level generic reactor and site remediation strategies already exist. At the lower level, various generic decommissioning reference processes and project options need development. For the past year, Environmental Services has held responsibility to respond to the Nuclear Installations Inspectorates' quinquennial review, develop and maintain up-to-date strategies, institute the review of a selected number of key strategies, and respond to changing circumstances including stakeholder views. Environmental Services is performing a range of generic studies for selection of strategies and end-points as used for a variety of waste management and site care and maintenance preparations. (author)

Fabrication of flasks for the transport of irradiated Magnox fuel elements

International Nuclear Information System (INIS)

Hamill, R.K.; Sandlan, R.

1979-01-01

A programme for the manufacture of rectangular box shaped fuel element flasks was undertaken and the paper sets out to describe some of the associated technical work. Alternative ways of making the flask bodies were considered in the light of the specified fracture toughness requirements and the successful achievement of these properties by the use of forgings is described in the paper. Welding to the body forgings, particularly of the fins attached around the four sides was characterised by extremely tight alignment tolerances. The reasons for adopting the method chosen and the success achieved are outlined. Particular attention was paid to preheat and the means of maintaining the requirement throughout manufacture are described. Procedure development work was conducted to establish and qualify the cladding of the top face by Type 347 stainless steel using the submerged arc strip method. A more unusual aspect of the manufacturing sequence was the attachment of thin nickel sheet to the base and cover plate of each flask to provide thermal insulation. The method adopted was spot welding using the MIG process and some of the problems which had to be overcome both in the welding itself and in the subsequent dressing of the spot welds are described. (author)

Status of spent fuel management in the United Kingdom

International Nuclear Information System (INIS)

Dodds, R.

1996-01-01

Nuclear generating capacity in the UK is static with no units currently under construction following the completion of the Sizewell B PWR. The Government's reviews of nuclear energy policy and radioactive waste management policy have been published following a public consultation procedure, largely with an endorsement of current policies. Nuclear Electric plc (NE) and Scottish Nuclear Limited's (SNL) AGR and PWR stations are to be privatised as two subsidiaries of a holding company, and it is planned that the Magnox stations and their liabilities will be kept in the public sector, initially in a stand alone company but ultimately integrated with BNFL. Prompt reprocessing of all Magnox fuel will continue. NE and SNL have signed contracts for extensive reprocessing of AGR fuel. In addition, SNL has agreed contractual arrangements with BNFL for long term storage of its remaining overlife arisings of AGR fuel and has therefore on commercial ground opted not to dry store their fuel at the reactor site. NE have not yet made a decision on the fate of their AGR fuel not covered by existing reprocessing contracts. No option selection has taken place for PWR fuel. Following the closure of the Dounreay PFR and the withdrawal from the EFR project, the option of recycle of plutonium in fast reactors has been suspended. (author)

Report and accounts 1994-1995

International Nuclear Information System (INIS)

1995-02-01

Nuclear Electric is the company which has been responsible for the United Kingdom government's nuclear power programme in England and Wales for the past five years. The report for 1994/95 shows that the company profits have increased by pound 422M to pound 1,218M reflecting a reduction in operating costs; this includes income from the Fossil Fuel Levy. Productivity, in terms of electricity output per employee, improved by 11% at the year end. Unit costs of electricity fell for the fifth consecutive year to 2.7p/kWR. Generation from the company's Magnox power stations increased by 1%. However, a reduction of total generation to 59.2 TWR compared to 61.0 TWR compared to 61.0 TWR in 1992/93 occurred as a consequence of extended outages in two of the AGR units to verify that hairline cracks in steam pipework welds would not compromise safety. In February, the completed Sizewell B reactor, the United Kingdom's first PWR, started supplying electricity to the grid. Another significant development during the year has been the government decision to privatise Nuclear Electric's AGR and PWR business while retaining the Magnox business in the public sector. Other aspects of the company's activities reviewed include: health and safety; environment; radioactive waste management; and decommissioning. The Directors' report and accounts are appended. (UK)

Risk-oriented analysis of the German prototype fast breeder reactor SNR-300: off-site accident consequence model and results of the study

International Nuclear Information System (INIS)

Bayer, A.; Ehrhardt, J.

1984-01-01

Accident off-site consequence calculations and risk assessments performed for the ''risk oriented analysis'' of the German prototype fast breeder reactor SNR-300 were performed with a modified version of the off-site accident consequence model UFOMOD. The modifications mainly relate to the deposition and resuspension processes, the ingestion model, and the dose factors. Consequence calculations at the site of Kalkar on the Rhine River were performed for 115 weather sequences in 36 wind directions. They were based on seven release categories evaluated for the SNR-300 with two different fueling strategies: plutonium from Magnox reactors only and plutonium from light water reactors and Magnox reactors. In parallel, the corresponding frequencies of occurrence are determined. The following results are generated: 1. complementary cumulative frequency distribution functions for collective fatalities and collective doses 2. expected values of the collective fatalities and collective doses as well as distance-dependent expected values of individual fatality 3. contributions of the different exposure pathways to fatalities with respect to the various organs. For comparison with the risk of a PWR-1300, calculations for the PWR-1300 of the ''German Risk Study'' were repeated with the same modified consequence model. Comparison shows that smaller risks result for the SNR-300. However, the confidence interval bandwidths obtained for the frequencies of the release categories for the SNR-300 are larger than those of the PWR-1300

Fuel Cycle and Waste Newsletter, Vol. 7, No. 2, September 2011

International Nuclear Information System (INIS)

2011-09-01

This issue contains the following topics: Fukushima clean-up; The nuclear world continues to change, whether we want it to or not; Decontaminating radioactive water using mobile technologies; Spent fuel management post-Fukushima; Yes, it will be safe; Leading spent fuel repository project reached its full length; Magnox decommissioning: an IAEA peer review; Mission to Malaysia: the Lynas project; the Internet reactor; New research reactor database interface; Converting research reactors from high to low enriched uranium; The IAEA peaceful uses initiative.

Country report for the UK

International Nuclear Information System (INIS)

Hesketh, Kevin

2001-01-01

Status of nuclear power generation in Britain can be summarised as follows: 7 Agr type reactors and 1 PWR, capacity 9.6 GW, and 7 Magnox reactors, capacity 2.9 GW. The fast reactors research and development programme is not sponsored by the Government, except for decommissioning work at Dounreay. Small BNFL-founded programme involves technology in fast reactor research and development in several fields: knowledge preservation, Capran-Cuadra European cooperation; Eu fifth framework activities; collaboration with Japanese research organisations

Funding Decommissioning - UK Experience

International Nuclear Information System (INIS)

MacKerron, Gordon

2006-01-01

'Funding' started with CEGB and SSEB (state-owned electric utilities) in 1976 using the internal un-segregated fund route (i.e unfunded). This continued until privatisation of electricity industry (excluding nuclear) in 1990. Assets bought with the internal un-segregated fund were mostly transferred into non-nuclear private utilities. New state-owned Nuclear Electric (England and Wales) was given a 'Fossil Fuel Levy', a consumer charge of 10% on retail bills, amounting to c. BP 1 bn. annually. This allowed Nuclear Electric to trade legally (A reserve of BP 2.5 bn. was available from Government if company ran out of money). By 1996 the newer nuclear stations (AGRS plus PWR) were privatised as British Energy. British Energy started an external segregated fund, the Nuclear Decommissioning Fund, with a starting endowment of c. BP 225 m. - and BE made annual contributions of British Pound 16 m. into the Fund. Assumptions were that BE had 70 to accumulate cash and could get a 3.5% average annual real return. Older stations (Magnox) were left in private sector and went to BNFL in 1997. Magnox inherited the surplus cash in BE - mostly unspent Fossil Fuel Levy receipts - of c. BP 2.6 bn. Government gave an 'Undertaking' to pay BP 3.8 bn. (escalating at 4.5% real annually) for Magnox liabilities, should Magnox Electric run out of cash. BNFL inherited the BP 2.6 bn. and by 2000 had a 'Nuclear Liabilities Investment Portfolio' of c. BP 4 bn. This was a quasi-segregated internal fund for liabilities in general. [Note: overall UK nuclear liabilities in civilian sector were running at c. BP 48 bn. by now]. BE started profitable and paid BP 100 m. annually in dividends to private investors for several years. BE ran into severe financial problems after 2001 and Government organised restructuring aid, now approved by European Commission. Terms include: - BE now to contribute BP 20 m. a year into an expanded Nuclear Liabilities Fund; - A bond issue of BP 275 m. to go to Fund; - 65

The waste management implications of decommissioning

International Nuclear Information System (INIS)

Passant, F.H.

1988-01-01

Decommissioning policy can only be framed in the light of radioactive waste management policy. What can be done with the waste materials, how and when, will determine the overall decommissioning plans and costs. In this paper the waste management options and their costs are reviewed for the decommissioning of the Central Electricity Generating Boards civil nuclear power stations. The paper concentrates on the decommissioning of Magnox stations, although comparative information on waste volumes and costs are given for the AGR programme and a typical PWR. (author)

Reduction of BNFL discharges: The Alara Principle

International Nuclear Information System (INIS)

Mummery, P.W.

1986-01-01

Although the title identified as the subject is rather broad, it is proposed to concentrate on liquid waste discharges from Sellafield to illustrate the range of considerations in practise. Such discharges arise from the nature of the work carried out at Sellafield. This comprises principally storage of spent fuel elements, magnox AGR and LWR, dismanteling and reprocessing of spent fuel and storage of recovered uranium and plutonium, manufacture of plutonium-based fuel for the prototype fast reactor at Dounreay, and management of the resulting wastes

Fire safety in atomic power plants

International Nuclear Information System (INIS)

Kench, R.L.; British Insurance

1988-01-01

The main reactor types are described briefly - Magnox, advanced gas cooled, pressurized water and fast reactors. Fire risks exist at fuel stores and spent fuel storage facilities. Simple fire prevention measures are suggested. Solid radioactive wastes can also be combustible. Various fire prevention measures for the different storage methods, eg compaction, are given. Gaseous and liquid wastes are also considered. The main types of reactor accident are described and the causes of four incidents - at Chernobyl, Windscale, Brownsferry and Three Mile Island, are examined. (U.K.)

For sale: 7 AGR stations and a brand new PWR

International Nuclear Information System (INIS)

Anon.

1995-01-01

Britain's seven AGR stations and the Sizewell B PWR will pass to private ownership under the UK government's plan to privatise the two nuclear generators, Nuclear Electric and Scottish Nuclear, sometime next year. Under the new set-up, the two generators will become operating subsidiaries of a holding company which will be headquartered in Scotland. The companies' ageing Magnox gas-cooled reactors will remain in a separate public sector company before being transferred to British Nuclear Fuels (BNFL) at the time of privatisation. (author)

Laser robot in the nuclear industry

International Nuclear Information System (INIS)

Contre, M.

1987-05-01

Possibilities of power lasers for welding, cutting, drilling, plugging surface treatment and hard-facing are reviewed. CO 2 and Nd:YAG lasers only have adequate power for nuclear applications. Radiation effects on lasers and contamination problems are examined. Then examples of applications to nuclear industry are given: PWR fuel fabrication, oxide thickness measurement in Magnox reactors, laser cutting of a cylindrical piece of steel on the bottom of a fuel channel in a gas graphite reactor, nuclear plant dismantling and fuel reprocessing. 51 refs [fr

Immobilization and leaching mechanisms of radwaste in cement-based matrices

International Nuclear Information System (INIS)

Glasser, F.P.; Rahman, A.A.; Crawford, R.W.; McCullough, C.E.; Angus, M.J.

1983-01-01

The effect of potential sorbers including silicas, titania, calcined kaolin, zirconium phosphate and two crystalline calcium silicates, tobermorite and xonotlite, have been used to improve the Cs-retention capacity of cement-based systems. The analysis of the pore fluid compositions of equilibrated cement-radwaste composites provides evidence concerning the leach mechanisms whereby Cs is removed. The reactions occurring between cement and clinoptilolite are elucidated and results of kinetic studies presented. Simulate Magnox waste is shown to react with cement, leading to a carbonate exchange. (author)

CEGB's radioactive waste management strategy

International Nuclear Information System (INIS)

Passant, F.H.; Maul, P.R.

1989-01-01

The Central Electricity Generating Board (CEGB) produces low-level and intermediate-level radioactive wastes in the process of operating its eight Magnox and five Advanced Gas Cooled Reactor (AGR) nuclear power stations. Future wastes will also arise from a programme of Pressurised Water Reactors (PWRs) and the decommissioning of existing reactors. The paper gives details of how the UK waste management strategy is put into practice by the CEGB, and how general waste management principles are developed into strategies for particular waste streams. (author)

Derived ERLs for inhalation of alpha-emitting aerorols

International Nuclear Information System (INIS)

Macdonald, H.F.

1977-01-01

Derived alpha action levels are expressed as dpm/m 3 and give the airborne concentration of an assumed mixture of α-emitters which if inhaled for a period of 4 hours would result in a dose commitment to members of the critical group in the exposed population equal to the emergency reference levels (ERLs) of dose recommended by the Medical Research Council (1975). The period of 4 hours is chosen as a realistic time during which an assessment of the severity of a release may be made and appropriate countermeasures instituted. The derived α ERLs are set with reference to the potential range of isotopic releases for a specific reactor system and in the case of gas-cooled magnox reactors, a value of 10 3 dpm/m 3 (170 Bqm -3 ) has been used. This level was based upon the lung and GI tract models originally recommended by ICRP 2 (1959:1964) and revised ERLs for the inhalation of α-emitters consequent upon the improved metabolic models subsequently proposed by the ICRP (1966:1972) are evaluated. It is shown that the derived α ERLs for irradiated magnox and AGR fuels are largely independent of the physico-chemical forms of the released material, while variations with cooling time of fuel are also discussed. In addition, the special limits imposed by the chemical toxicity of uranium when inhaled in a soluble, low enriched form are briefly outlined

Revised estimates of the radiological impact of the transport of irradiated nuclear fuels within the UK

International Nuclear Information System (INIS)

Macdonald, H.F.

1987-10-01

This report presents revised estimates of individual and collective doses associated with irradiated fuel movements from CEGB and SSEB nuclear power stations within the UK. In particular, earlier estimates of transport doses have been updated to take account of recent changes in the patterns of rail traffic. This results in a reduction in the estimated maximum individual doses to members of the public living near marshalling yards where flasks stop en route and also to rail workers incidentally exposed at these locations. The maximum levels of individual dose associated with irradiated fuel transport within the UK are in general low compared with those due to natural background radiation. Further, the associated collective doses are small compared with other sources of dose arising in the nuclear fuel cycle and represent -4 % of the natural background radiation dose to the UK population. In absolute terms the maximum contributions to the annual transport collective doses from Magnox, AGR and projected PWR fuel movements are estimated to be 18, 9 and 0.7 man mSv · a -1 respectively. These results neglect any reduction in doses due to the effects of shielding by buildings or natural obstacles such as railway cuttings or tunnels. Inclusion of these effects has been estimated to reduce the annual transport collective doses to 13, 6 and 0.45 man mSv · a -1 for Magnox, AGR and PWR fuels respectively. (U.K.)

Radioactive waste management at nuclear electric power stations

International Nuclear Information System (INIS)

Gordelier, S.C.

1993-01-01

After suitable treatment, gaseous and liquid wastes are routinely discharged from Nuclear Electric's stations and are diluted and dispersed in the environment. The discharges are controlled and authorized under UK legislation and the environmental impact is minimal. Most solid wastes were originally accumulated at the site of origin, but since 1978 low level wastes (LLW) have been send to the UK's main disposal site at Drigg. Recent changes at Drigg have resulted in changed arrangements for the transport and disposal of low-level wastes, including volume reduction by supercompaction. Small amounts of intermediate-level waste (ILW) have been conditioned and disposed of in the sea but this route is now effectively closed and there is currently no disposal route for ILW in the UK. Spent ion exchange resins at one power station have been conditioned and are stored pending the availability of a disposal route. Most ILW will continue to be stored in retrievable form on the site of origin until a mobile waste treatment plant can be brought into use. The timing of this will be subject to agreement with the regulators. In the case of Magnox fuel element debris, a demonstration dissolution plant has been constructed and this will significantly reduce the volume of waste being stored while retaining the bulk of the activity on site for later treatment. A further development has been the construction of a new facility which will hold Magnox fuel element debris in 500 liter drums

Magnox fuel dry storage and direct disposal assessment of CEGB/SSEB reports

International Nuclear Information System (INIS)

1987-12-01

This report assesses the Boards' presented work in response to Recommendations 17 and 18 of the Environment Committee's First Report (Jan 86). The Boards have made an extensive study of the dry store design and also considered direct disposal. Their basic conclusion that the financial advantage is with continued reprocessing is accepted with the comment that their storage and disposal costs may be on the high side. The Boards statements on drying wet-stored fuel and on improvement of the fuel's chemical stability are accepted. The Boards coverage of fuel after disposal is considered to be too brief; the assessment expresses a more pessimistic view than the Boards' of the acceptability of direct disposal. (author)

Annual report and accounts 1993-94

International Nuclear Information System (INIS)

1994-01-01

Scottish Nuclear produces almost half Scotland's electricity requirements from the two AGRs it owns and operates; Hunterston-B and Torness. It is also responsible for decommissioning the Magnox power station at Hunterson-A. In this report the company policy and a summary of its operation and technical programme are given. Unit generating costs have fallen over the preceding few years to 2.83 p/KWh in 1993/94. The accounts show an operating profit with a total profit of 472 million for the 1993/94 financial year. (UK)

A CEGB system for the assurance of quality in the commissioning of power plant

International Nuclear Information System (INIS)

Lake, M.W.

1984-01-01

This paper outlines a system of organization, documentation and surveillance which has been fully proven in practice and looks ahead to identify the arrangements for the organization, documentation, and audit which the CEGB proposes to use in the commissioning of the Sizewell 'B' PWR, so that quality may be assured. In the UK between 1967 and 1982, the CEGB commissioned approximately 40,000 M Watts of power plant. This comprised power plants that were coal fired, oil fired, water driven, gas turbine driven and nuclear (both magnox and advanced gas cooled (AGR) reactors)

Improvements in containers

International Nuclear Information System (INIS)

Guy, R.

1977-01-01

An improved container is described for transporting radioactive materials, such as irradiated Magnox fuel elements. It has a lid fixed to the container body and at the corners of the lid has shock absorbers that project from the corners and have part-spheroidal shape. The centre of curvature of the surface of the spheroid is positioned within the lid, so that impact loads on a shock absorber tend to hold it to the container rather than dislodge it. The shock absorbers may be Al-Si alloy castings. (U.K.)

BNFL Springfields Fuel Division

International Nuclear Information System (INIS)

Tarkiainen, S.; Plit, H.

1998-01-01

The Fuel Division of British Nuclear Fuels Ltd (BNFL) manufactures nuclear fuel elements for British Magnox and AGR power plants as well as for LWR plants. The new fuel factory - Oxide Fuel Complex (OFC), located in Springfields, is equipped with modern technology and the automation level of the factory is very high. With their quality products, BNFL aims for the new business areas. A recent example of this expansion was shown, when BNFL signed a contract to design and license new VVER-440 fuel for Finnish Loviisa and Hungarian Paks power plants. (author)

Session 1984-1985. Radioactive waste. Minutes of evidence, Monday 13 May 1985. British Nuclear Fuels plc

Energy Technology Data Exchange (ETDEWEB)

1985-01-01

The Environment Select Committee of the House of Commons received a memorandum from British Nuclear Fuels plc on the treatment and preparation for disposal of radioactive wastes, under the headings: introduction; waste categories; waste management policy; waste arisings; waste treatment plans; appendix I - British Nuclear Fuels plc; appendix II - the nuclear fuel cycle for Magnox, AGR and LWR reactors; appendix III - control of liquid radioactive discharges from Sellafield and their environmental impact. Representatives of BNF plc were examined on the subject of the memorandum and the minutes of evidence are recorded.

Dry storage of irradiated nuclear fuels and vitrified wastes

International Nuclear Information System (INIS)

Deacon, D.

1982-01-01

A review is given of the work of GEC Energy Systems Ltd. over the years in the dry storage of irradiated fuel. The dry-storage module (designated as Cell 4) for irradiated magnox fuel recently constructed at Wylfa nuclear power station is described. Development work on the long-term dry storage of irradiated oxide fuels is reported. Four different methods of storage are compared. These are the pond, vault, cask and caisson stores. It is concluded that there are important advantages with the passive air-cooled ESL dry stove. (U.K.)

Recent developments: Industry briefs

International Nuclear Information System (INIS)

Anon.

1992-01-01

The January 1992 Industry Briefs includes brief articles on: (1) the startup of Chinese and Indian nuclear units, (2) agreements between China and Pakistan for the construction of a nuclear unit, (3) international safeguards agreements, (4) restart of a nuclear unit in Armenia, (5) closure of a German nuclear waste site, (6) restructuring of the Hungarian state-owned utility MVMT, (7) requests for bids for Wolsong Units 3 and 4, (8) signing of the European Energy charter, (9) continued operation of the MAGNOX reactors, and (10) changing Canadian requirements on uranium

Session 1984-85. Radioactive waste. Minutes of evidence, Monday 13 May 1985. British Nuclear Fuels plc

International Nuclear Information System (INIS)

1985-01-01

The Environment Select Committee of the House of Commons received a memorandum from British Nuclear Fuels plc on the treatment and preparation for disposal of radioactive wastes, under the headings: introduction; waste categories; waste management policy; waste arisings; waste treatment plans; appendix I - British Nuclear Fuels plc; appendix II - the nuclear fuel cycle for Magnox, AGR and LWR reactors; appendix III - control of liquid radioactive discharges from Sellafield and their environmental impact. Representatives of BNF plc were examined on the subject of the memorandum and the minutes of evidence are recorded. (U.K.)

Nuclear power. Its development in the United Kingdom

International Nuclear Information System (INIS)

Pocock, R.F.

1977-01-01

The subject is covered chronologically in chapters, entitled: from war to peace; the Atomic Energy Authority and the first nuclear power station; a civil power programme; Windscale - the need for caution; research for the future; the new (Magnox) power stations; revision of the nuclear power programme; supply of nuclear fuels; nuclear power for ship propulsion; completion of first programme; Dungeness B and second programme, political assessment of (nuclear) industry's structure; reorganization of the industry; nuclear power in the environment; completion of second programme; the energy crisis; decision on third programme. (U.K.)

Plutonium re-cycle in HTR

Energy Technology Data Exchange (ETDEWEB)

Desoisa, J. A.

1974-03-15

The study of plutonium cycles in HTRs using reprocessed plutonium from Magnox and AGR fuel cycles has shown that full core plutonium/uranium loadings are in general not feasible, burn-up is limited due the need for lower loadings of plutonium to meet reload core reactivity limits, on-line refueling is not practicable due to the need for higher burnable poison loadings, and low conversion rates in the plutonium-uranium cycles cannot be mitigated by axial loading schemes so that fissile make-up is needed if HTR plutonium recycle is desired.

A Survey of the Fuel Cycles Operated in the United Kingdom; Etude d'ensemble sur les cycles de combustible au Royaume-Uni; Obzor toplivnykh tsiklov, ispol'zuemykh v soedinennom korolevstve; Estudio de los ciclos de combustible utilizados en el Reino Unido

Energy Technology Data Exchange (ETDEWEB)

Allday, C. [United Kingdom Atomic Energy Authority, Risley, Warrington, Lancs (United Kingdom)

1963-10-15

(a) The natural uranium/ magnox fuel cycle. The United Kingdom have chosen the natural uranium graphite-moderated gas-cooled reactor as the basis of their nuclear power programme. They have operated the reactors at Calder Hall and Chapelcross for seven years; the Berkeley and Bradwell reactors of the CEGB are now operating, and reactors at seven other sites are under construction or planned. The fuel for these reactors is designed and manufactured at the U.K.A.E.A. Springfields factory and then transported to the reactor site for loading. After irradiation and discharge the fuel is transported to the U.K.A.E.A. site at Windscale for separation of uranium and plutonium from fission products. The paper outlines the UK experience of design and manufacture of fuel, re actor operation, transport of irradiated fuel and subsequent processing of the fuel. Mention is made of the behaviour of fuel in a reactor and alternative charging and discharging programmes, the subject is further elaborated in another paper. (b) Reactors using enriched fuels. The UK are developing an advanced gas-cooled reactor (AGR), the prototype reactor of which came on power in 1963. The fuel is manufactured from enriched uranium oxide canned in stainless steel and it will be reprocessed through a ''head-end'' which will be added to the Windscale Magnox separation plant. The enriched uranium for the AGR is produced in the UK Diffusion Plant at Capenhurst. An alternative to enriched uranium oxide as a fuel is plutonium-enriched natural-uranium oxide. The paper outlines the experience in production of oxide fuel for AGR, the operating experience with the reactor so far and the plans for reprocessing the fuel. The alternative use of a plutonium fuel is considered and the effects of this on costs and the fuel cycle. Finally the paper outlines the place of Magnox and AGR reactors in the UK power programme. (author) [French] a) Cycle de l'uranlum naturel gaine de magnox. Le Royaume-Uni a choisi de fonder

Gas cooled reactor decommissioning. Packaging of waste for disposal in the United Kingdom deep repository

International Nuclear Information System (INIS)

Barlow, S.V.; Wisbey, S.J.; Wood, P.

1998-01-01

United Kingdom Nirex Limited has been established to develop and operate a deep underground repository for the disposal of the UK's intermediate and certain low level radioactive waste. The UK has a significant Gas Cooled Reactor (GCR) programme, including both Magnox and AGR (Advanced Gas-cooled Reactor) capacity, amounting to 26 Magnox reactors, 15 AGR reactors as well as research and prototype reactor units such as the Windscale AGR and the Windscale Piles. Some of these units are already undergoing decommissioning and Nirex has estimated that some 15,000 m 3 (conditioned volume) will come forward for disposal from GCR decommissioning before 2060. This volume does not include final stage (Stage 3) decommissioning arisings from commercial reactors since the generating utilities in the UK are proposing to adopt a deferred safe store strategy for these units. Intermediate level wastes arising from GCR decommissioning needs to be packaged in a form suitable for on-site interim storage and eventual deep disposal in the planned repository. In the absence of Conditions for Acceptance for a repository in the UK, the dimensions, key features and minimum performance requirements for waste packages are defined in Waste Package Specifications. These form the basis for all assessments of the suitability of wastes for disposal, including GCR wastes. This paper will describe the nature and characteristics of GCR decommissioning wastes which are intended for disposal in a UK repository. The Nirex Waste Package Specifications and the key technical issues, which have been identified when considering GCR decommissioning waste against the performance requirements within the specifications, are discussed. (author)

Questions for the nuclear installations inspectorate

International Nuclear Information System (INIS)

Conroy, C.; Flood, M.; MacRory, R.; Patterson, W.C.

1976-01-01

The responsibilities of the Nuclear Installations Inspectorate are considered, and the responsibilities of other bodies for (a) reprocessing and enrichment, and (b) security. Questions for the Nuclear Installations Inspectorate are then set out under the following heads: general (on such topics as vandalism, sabotage, threats, security, reactor incidents); magnox reactors; corrosion; advanced gas-cooled reactor; steam generating heavy water reactor; fast breeder reactor; reproces-sing and waste. Most of the questions are concerned with technical problems that have been reported or might possibly arise during construction or operation, affecting the safety of the reactor or process. (U.K.)

Sellafield - a nuclear licensed site

International Nuclear Information System (INIS)

Bloom, Phillipa.

1987-01-01

The report is based on the experience gained when visiting the Exhibition Centre at the BNFL Sellafield site and joining the hour-long coach trip round the site. The sights are recorded and a description given of the processes undertaken at Sellafield to reprocess the Magnox fuel and store the spent fuel from AGR reactors. The purpose of the main plant building, and the passage of the spent fuel through the various processes is described. Criticism is made of the safety record at Sellafield and a full and open debate on nuclear power is called for. (UK)

Dewatering of sludges

International Nuclear Information System (INIS)

Bode, P.

1984-01-01

A filter rig has been designed and built. Simulated magnox and alumino ferric hydroxide sludges have been successfully filtered on this equipment and both types of sludge produced a clear filtrate and a cake. The flow rates were low. The cake often partially remained adhered to the filter membrane instead of dropping clear during the filter cleaning cycle. This filtration technique can only be used on sludges which form a non-binding cake. Permeability of the membrane can be altered by stretching. Irradiation of the membrane showed that it should withstand 20 to 50 M.rads. (author)

A History of Dosimetry for the Advanced Gas-cooled Reactors

Directory of Open Access Journals (Sweden)

Shaw Simon

2016-01-01

Full Text Available This paper presents a summary of the methods used in the first ∼40 years of AGR neutron dosimetry and nuclear heating calculations, and the influence of the earlier Magnox reactor dosimetry programme. While the current state-of-the-art Monte Carlo methods are extremely powerful they still require very careful consideration of the quality of the input data, nuclear data validation and variance reduction techniques; in particular, this paper examines the difficulties in assuring the adequate convergence of calculations when Monte Carlo acceleration is applied in the presence of significant streaming paths through attenuating or scattering media.

Manufacture of steam generator units and components for the AGR power stations at Heysham II and Torness

International Nuclear Information System (INIS)

Glasgow, J.R.; Parkin, K.

1984-01-01

The current AGR Steam Generator is a development of the successful once-through units supplied for the Oldbury Magnox and Hinkley B/Hunterston B AGR power stations. In this paper a brief outline of the evolution of the steam generator design from the earlier gas cooled reactor stations is presented. A description of the main items of fabrication development is given. The production facilities for the manufacture of the units are described. Reference is also made to some of the work on associated components. The early experience on the construction site of installation of the steam generators is briefly outlined. (author)

Manufacture of steam generator units and components for the AGR power stations at Heysham II and Torness

Energy Technology Data Exchange (ETDEWEB)

Glasgow, J R; Parkin, K [N.E.I. Nuclear Systems Ltd., Gateshead, Tyne and Wear (United Kingdom)

1984-07-01

The current AGR Steam Generator is a development of the successful once-through units supplied for the Oldbury Magnox and Hinkley B/Hunterston B AGR power stations. In this paper a brief outline of the evolution of the steam generator design from the earlier gas cooled reactor stations is presented. A description of the main items of fabrication development is given. The production facilities for the manufacture of the units are described. Reference is also made to some of the work on associated components. The early experience on the construction site of installation of the steam generators is briefly outlined. (author)

Annual report and accounts 1992-93

International Nuclear Information System (INIS)

1993-07-01

Scottish Nuclear Limited is Scotland's nuclear power generating company. The Annual Report and Accounts for 1992-1993 are presented. The Company is owned by the Secretary of State for Scotland and supplies all its electricity to Scottish Power (74.9%) and Scottish Hydro-Electric (25.1%). It produces almost half of Scotland's electricity requirements. The Company owns and operates the Advanced Gas-Cooled Reactor (AGR) nuclear power stations at Hunterston on the Firth of Clyde and at Torness on the East Coast of Scotland. It is also responsible for the decommissioning of the magnox nuclear power station, Hunterston A. (Author)

The development of criteria for the design of insulation for nuclear reactors

International Nuclear Information System (INIS)

Furber, B.N.; Hopkins, I.H.G.; Stuart, R.A.

1976-01-01

In 1960 when the early design studies for the Oldbury Power Station were being carried out the use of insulation in a reactor environment was quite novel. No manufacturer had previous experience of this particular application of insulation. The paper describes the work carried out to establish the design criteria for Magnox and subsequent Advanced Gas Cooled Reactors (AGR) and indicates some of the new problems of the High Temperature Reactor (HTR). Unless otherwise stated the work was carried out by The Nuclear Power Group Ltd. (TNPG) and the conclusions express the present thinking of that Company. (author)

Nuclear electricity - a progress report

International Nuclear Information System (INIS)

England, G.

1980-01-01

A survey of the progress of nuclear power over the past three years reveals three major features: (i) the continued operation of the first generation of commercial nuclear power stations, based on the Magnox gas-cooled reactor; (ii) the introduction and operation of the first of the second-generation stations, based on the advanced gas-cooled reactor (AGR); and (iii) the commitment of two successive Governments to a flexible thermal reactor strategy. Each of these features is considered and a number of related issues, including the safety record and cost savings to the electricity consumer, are discussed. (author)

Sophisticated fuel handling system evolved

International Nuclear Information System (INIS)

Ross, D.A.

1988-01-01

The control systems at Sellafield fuel handling plant are described. The requirements called for built-in diagnostic features as well as the ability to handle a large sequencing application. Speed was also important; responses better than 50ms were required. The control systems are used to automate operations within each of the three main process caves - two Magnox fuel decanners and an advanced gas-cooled reactor fuel dismantler. The fuel route within the fuel handling plant is illustrated and described. ASPIC (Automated Sequence Package for Industrial Control) which was developed as a controller for the plant processes is described. (U.K.)

Review of experience with plutonium exposure assessment methodologies at the nuclear fuel reprocessing site of British Nuclear Fuels plc

International Nuclear Information System (INIS)

Strong, R.

1988-01-01

British Nuclear Fuels plc and its predecessors have provided a complete range of nuclear fuel services to utilities in the UK and elsewhere for more than 30 years. Over 30,000 ton of Magnox and Oxide fuel have been reprocessed at Sellafield. During this time substantial experience has accumulated of methodologies for the assessment of exposure to actinides, mainly isotopes of plutonium. For most of the period monitoring of personnel included assessment of systemic uptake deduced from plutonium-in-urine results. The purpose of the paper is to present some conclusions of contemporary work in this area

The engineering function in Scottish Nuclear

International Nuclear Information System (INIS)

Grant, J.

1991-01-01

The work of the Engineering and Development Division of Scottish Nuclear is described in this article. This company, formed since the privatization of electricity generation in the United Kingdom, owns and operates the two Hunterston Magnox reactors and the Torness Advanced Gass Cooled Reactors. Principle responsibilities such as maintaining safety standards, formulating policy for radioactive waste disposal and decommissioning and optimally controlling the nuclear generation cycle are outlined. Objectives for the next five years are identified and explained separately. The experience, knowledge and expertise of engineering staff is stressed as being of key importance to the future success of Scottish Nuclear. (UK)

The encapsulation of Magnox type fuel elements for extended storage in cooling ponds

International Nuclear Information System (INIS)

Baker, D.W.C.; Burt, G.A.

1978-01-01

A method of encapsulating spent fuel elements in a protective plastics medium to enable them to be stored for protracted periods under water, without risk of further significant corrosion, has been developed. It is visualised that the elements after discharge from the reactor would be allowed to cool under water for a period of at least 100 days and would then be encapsulated while remaining immersed. A suitable two pack system based on a solvent free epoxy resin cured with an aromatic amine adduct has been identified. The equipment and processes which have been developed for handling, conditioning and encapsulating the fuel are described. (author)

The decommissioning of Berkeley II

International Nuclear Information System (INIS)

Hannan, A.

2002-01-01

This paper describes the decommissioning progress at the Magnox site at Berkeley in Gloucestershire.Throughout the work at Berkeley the emphasis has been on conducting decommissioning safely. This has been reflected in the progress of decommissioning starting with removal of the fuel from site and thus much greater than 99% of the radioactive inventory. The major radioactive hazard is the Intermediate Level Waste in the form of fuel element debris (graphite struts and extraneous magnox components removed to increase the packing density of fuel elements in flasks going to Sellafield), miscellaneous activated components, sludges and resins. Approximately 1500 m 3 of such material exists and is stored in underground waste vaults on site. Work is underway to recover and encapsulate the waste in cement so rendering it 'passively safe'. All work on site is covered by a nuclear safety case which has a key objective of minimising the radiological exposures that could accrue to workers. Reflecting this an early decision has been taken to leave work on the Reactor Pressure Vessels themselves for several decades. Also important in protection of the workforce has been control of asbestos.Much material has been removed with redundant plant and equipment, but a programme of remediation in line with government legislation has been required to ensure personnel safety throughout the decommissioning period and into Care and Maintenance.In addition to health and safety matters the site approach to environmental issues has been consistent. Formally such standards as ISO 14001 have been adhered to and the appropriate certification maintained. At a working level the principles of reduce, reuse and recycle have been inculcated

Temperature measurement of the reactor materials samples irradiated in the fuel channels of the RA reactor - Annex 16; Prilog 16 - Merenje temperature uzoraka reaktorskih materijala ozracivanih u gorivnim kanalima reaktora RA

Energy Technology Data Exchange (ETDEWEB)

Nikolic, M; Djalovic, M [Institute of Nuclear Sciences Boris Kidric, Reaktor RA, Vinca, Beograd (Serbia and Montenegro)

1964-12-15

Reactor materials as graphite, stainless steel, magnox, zirconium alloys, etc. were exposed to fast neutron flux inside the fuel elements specially adapted for this purpose. Samples in the form ampoules were placed in capsules inside the fuel channels and cooled by heavy water which cools the fuel elements. In order to monitor the samples temperature 42 thermocouples were placed in the samples. That was necessary for reactor safety reasons and for further interpretation of measured results. Temperature monitoring was done continuously by multichannel milivoltmeters. This paper describes the technique of introducing the thermocouples, compensation instruments, control of the cold ends and adaptation of the instruments for precision (0.5%) temperature measurement in the range 30 deg - 130 deg C; 30 deg - 280 deg C and 30 deg - 80 deg C. Ozracivanje uzoraka materijala za izgradnju reaktora kao sto su grafit, nerdjajuci celik, magnox, legure cirkonijuma, aluminijuma itd. vrseno je u fluksu brzih neutrona unutar samih gorivnih elemenata koji su specijalno adaptirani za ovu svrhu. Uzorci u vidu ampula smesteni su u kapsulu od aluminijuma i postavljeni unutar kanala gde su hladjeni cirkulacijom teske vode koja hladi same gorivne elemente. U cilju kontrole temperature uzoraka radi bezbednosti samog reaktora, kao i radi kasnije interpretacije rezultata ispitivanja radijacionog ostecenja materijala, ugradjeno je 42 termopara u uzorke. Kontrola temperature je vrsena kontinualno visekanalnim registratorima. U radu je prikazana tehnika izvodjenja termoparova, kompenzacionih vodova, kontrola hladnih krajeva i prilagodjenje instrumentacije za merenje i registraciju temperature sa tacnoscu 0,5% u opsezima 30 deg - 130 deg C; 30 deg - 280 deg C i 30 deg - 80 deg C (author)

The contribution of nuclear training staff to human factors work in the CEGB and Nuclear Electric PLC

International Nuclear Information System (INIS)

Madden, V.J.

1990-01-01

The staff and simulators of utility's nuclear training function are being utilized in support of a wide range of human factor related activities. In addition to work on man machines interface review, operating procedures, operator support system and VDU format design and validation for the Magnox and AGR series of nuclear power plants, support is also being provided to the PWR Project Team through staff who have undergone extensive and comprehensive overseas PWR training programs. This paper discusses how recent initiatives in connection with a survey on operator stress and the possible use of psychometric testing in support of the selection of reactor desk engineers are also being supported

The use of simulation on courses at the CEGB's nuclear power training centre

International Nuclear Information System (INIS)

Madden, V.J.; Tompsett, P.A.

1986-01-01

Simulation used during training courses held at the Central Electricity Generating Board's (CEGB's) Nuclear Power Training Centre takes the form of desk-top kinetics units, generic Magnox and plant specific Advanced Gas Cooled Reactor (AGR) simulators. This paper reviews the CEGB's experience in the training use of the first three AGR simulators and describes both the developments made since their first commissioning and those currently envisaged. The Heysham 2 simulator is compared with the earlier units and its use during training courses is discussed. The role of the tutor in the provision of simulator training is considered together with the various facilities which he controls. (author)

The management of change in BNFL's UK group with particular reference to the restructuring of the health and safety functions

International Nuclear Information System (INIS)

Brandwood, A.R.

1996-01-01

BNFL's UK group business involves reprocessing of uranium metal (Magnox) fuel, storage and dismantling of advanced gas rector (ceramic UO 2 ) fuel, waste treatment and storage, decommissioning and electricity generation. These activities are carried out at three sites in the North West corner of England and Southern Scotland: Sellafield - all activities, Chapelcross -electricity generation, Drigg - waste storage. Achieving fundamental change in a well established nuclear business which is highly regulated is possible and can bring large benefits. The keys to success are leadership and commitment from all senior managers, involvement of all stakeholders and communication. It is essential to involve the regulator as a stakeholder. (author)

Preparation for commissioning of nuclear plant with reference to British Nuclear Fuels Plc fuel handling plant project

International Nuclear Information System (INIS)

Bamber, D.R.

1987-01-01

The new Fuel Handling Plant at British Nuclear Fuels Sellafield is part of a Pound 550M complex which provides facilities for the receipt, storage and mechanical preparation of both Magnox and A.G.R. fuel. The plant is very large and complex with considerable use of computer based process control systems, providing for physical and nuclear safety. The preparation of such plant for active commissioning necessitates a great many physical checks and technical evaluations in support of its safety case. This paper describes arrangements for plant commissioning checks, against the regulatory framework and explains the physical preparations necessary for their timely accomplishment. (author)

Report and accounts 1991-92

International Nuclear Information System (INIS)

1992-01-01

In the second full year of operation, Nuclear Electric has improved its competitive position and increased operating profits are recorded. The long-term aim is to be profitable without the fossil-fuel levy. The operating record of Nuclear Electric's Magnox and AGR power stations, progress on Sizewell-B and the decommissioning of Berkeley Station are recorded. The year 1991/92 is reviewed; the commercial, production and fuel operations are reported. Health and Safety - a main priority of Nuclear Electric is considered and Nuclear Electric's environmental policy is stated. Human resources, public relations and international affairs are covered. A statistical summary including the accounts is included. (UK)

Irradiated nuclear fuel transport from Japan to Europe

International Nuclear Information System (INIS)

Kavanagh, M.T.; Shimoyama, S.

1976-01-01

Irradiated nuclear fuel has been transported from Japan to Europe since 1969, although U.K. experience goes back almost two decades. Both magnox and oxide fuel have been transported, and the technical requirements associated with each type of fuel are outlined. The specialized ships used by British Nuclear Fuels Limited (BNFL) for this transport are described, as well as the ships being developed for future use in the Japan trade. The ship requirements are related to the regulatory position both in the United Kingdom and internationally, and the Japanese regulatory requirements are described. Finally, specific operational experience of a Japanese reactor operator is described

Preparation for commissioning of nuclear plant with reference to British Nuclear Fuels Plc fuel handling plant project

International Nuclear Information System (INIS)

Bamber, D.

1987-01-01

The new Fuel Handing Plant at British Nuclear Fuels Sellafield is part of a Pound 550M complex which provides facilities for the receipt, storage and mechanical preparation of both magnox and A.G.R. fuel. The plant is very large and complex with considerable use of computer based process control systems, providing for physical and nuclear safety. The preparation of such plant for ''active'' commissioning necessitates a great many physical checks and technical evaluations in support of its safety case. This paper describes arrangements for plant commissioning checks, against the regulatory framework and explains the physical preparations necessary for their timely accomplishment. (author)

Partnership - the heart of integrated outage management

International Nuclear Information System (INIS)

Robinson, F.T.

1995-01-01

Changes in the power generating industry continue apace. The effects of privatisation are widely visible: nowhere more so than in the growing national and international competition facing the generators around the world. A successful, long-term marriage between generator and contractor on power station outage management offers significant scope for cost reduction, shortening annual plant downtime and generating more megawatts, all within a safety environment of continuous improvement. Working in close partnership, Nuclear Electric and Rolls-Royce Nuclear Engineering Services have remodelled the whole contractor/client strategy. The new discipline, known as integrated outage management and partnering, is already producing shorter outage periods at Bradwell, a Magnox Station in Essex. (author)

Comportment of various magnesium alloys in carbon dioxide under pressure, between 400 and 600 deg; Compatibilite de divers alliages de magnesium avec le gaz carbonique sous pression entre 400 et 600 deg

Energy Technology Data Exchange (ETDEWEB)

Darras, R; Baque, P; Chevilliard, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

The following materials were studied: nuclear magnesium, two Mg-Zr alloys, a 'Magnox' type alloy, a Mg-Mn alloy and a 'sintered magnesium oxide'. The samples, taken from drawn metals, are suitably polished and given two reproducible surface conditions for purposes of comparison. The tests were carried out in purified carbon dioxide, at pressures of 25 to 60 atmospheres and temperatures from 400 to 600, using special, externally heated stainless steel autoclaves. The duration of the tests is generally more than 1000 hours. The equations of the weight increase curves obtained are of the type: ({delta}p){sup n} = k.t (({delta}p in mg/cm{sup 2} and t in hours), the index n being around 2, at least up to 500 deg. C. Referring to results obtained previously in the case of certain of these materials exposed to carbon dioxide at atmospheric pressure and at 15 atmospheres, it appears that: 1) for given material: - at a given pressure, oxidation increases with temperature, - at a given temperature oxidation increases with pressure, - under the same temperature and pressure conditions, the results vary little according to the two surface states studied; 2) Mg-Zr alloys show better oxidation resistance than non-alloyed magnesium; 3) The alloy magnox shows up much less favourably in carbon dioxide than in air, compared with the other alloys. Generally speaking, the oxidation curves tending towards a threshold after a certain exposure time, all the alloys considered appear to show a satisfactory compatibility with carbon dioxide up to a temperature around 500 deg. C, under the working conditions defined here; above 500, under differences appear between various alloys, but the sublimation phenomena interfere with those of oxidation, with the result that a classification of the various materials can only be based on their resultant. (author) [French] Les materiaux etudies comprennent: le magnesium nucleaire, deux alliages Mg-Zr, un alliage du type 'Magnox', un alliage Mg-Mn et un

On-site Destruction of Radioactive Oily Wastes Using Adsorption Coupled with Electrochemical Regeneration - 12221

Energy Technology Data Exchange (ETDEWEB)

Brown, N.W. [Arvia Technology Ltd, Daresbury Innovation Centre, Daresbury, WA4 4FS (United Kingdom); Wickenden, D.A. [Magnox Ltd, Berkeley Centre, Gloucestershire, GL13 9PB (United Kingdom); Roberts, E.P.L. [School of Chemical Engineering, University of Manchester, Manchester, M60 1QD (United Kingdom)

2012-07-01

Arvia{sup R}, working with Magnox Ltd, has developed the technology of adsorption coupled with electrochemical regeneration for the degradation of orphan radioactive oil wastes. The process results in the complete destruction of the organic phase where the radioactivity is transferred to liquid and solid secondary wastes that can then be processed using existing authorised on-site waste-treatment facilities.. Following on from successful laboratory and pilot scale trials, a full scale, site based demonstrator unit was commissioned at the Magnox Trawsfynydd decommissioning site to destroy 10 l of LLW and ILW radioactive oils. Over 99% of the emulsified oil was removed and destroyed with the majority of activity (80 - 90%) being transferred to the aqueous phase. Secondary wastes were disposed of via existing routes with the majority being disposed of via the sites active effluent treatment plant. The regeneration energy required to destroy a litre of oil was 42.5 kWh/l oil. This on-site treatment approach eliminates the risks and cost associated with transporting the active waste oils off site for incineration or other treatment. The Arvia{sup R} process of adsorption coupled with electrochemical regeneration has successfully demonstrated the removal and destruction of LLW and ILW radioactive oils on a nuclear site. Over 99.9% of the emulsified oil was removed, with the majority of the radioactive species transferred to the aqueous, supernate, phase (typically 80 - 90 %). The exception to this is Cs-137 which appears to be more evenly distributed, with 43% associated with the liquid phase and 33 % with the Nyex, the remainder associated with the electrode bed. The situation with Plutonium may be similar, but this requires confirmation, hence further work is underway to understand the full nature of the electrode bed radioactive burden and its distribution within the body of the electrodes. - Tritium gaseous discharges were negligible; hence no off-gas treatment

The regulation of technetium-99 discharges at Sellafield

International Nuclear Information System (INIS)

Mayall, A.

2002-01-01

The reprocessing of spent Magnox fuel at BNFL Sellafield produces a liquid waste concentrate containing technetium-99 and other, more radiotoxic, radionuclides such as plutonium and americium. The concentrate is known as medium active concentrate (MAC). Prior to 1981, MAC was discharged to sea untreated after several years' storage, during which short-lived radionuclides underwent radioactive decay. In the early 1980s, discharges of MAC were suspended and it was retained in storage tanks, pending the construction of a plant to remove the radionuclides of greatest radiological concern (these did not include technetium- 99). The Enhanced Actinide Removal Plant started operation in 1994 and began to clear the backlog of stored waste MAC, as well as current arisings from Magnox reprocessing. As a consequence technetium-99 was once more discharged to sea. Subsequently, concentrations of this radionuclide in the marine environment increased. In particular, there was a significant increase in the concentration of technetium-99 in lobster in the Irish Sea. An increase in technetium-99 has also been detected at locations far distant from Sellafield, e.g. in Scandinavian coastal waters, albeit at very low concentrations. This dispersal of technetium- 99 throughout the Irish Sea and further afield has therefore caused concern, although the radiological impact is low. This paper examines the nature and source of the technetium-99 in sea discharges at Sellafield and the levels of past and current discharges as well as their impact. It goes on to describe the Environment Agency's recent proposals on the future regulation of technetium-99 discharges and how these should lead to substantial reductions in not only technetium-99 discharges, but also of other radionuclides such as caesium-137 and strontium-90. (author)

Design and Implementation of Equipment for Enhanced Safeguards of a Plutonium Storage in a Reprocessing Plant

International Nuclear Information System (INIS)

Richir, P.; Dechamp, L.; Buchet, P.; Dransart, P.; Dzbikowicz, Z.; Peerani, P.; ); Pierssens, L.; Persson, L.; Ancius, D.; Synetos, S.; ); Edmonds, N.; Homer, A.; Benn, K.-A.; Polkey, A.

2015-01-01

The Nuclear Security unit (NUSEC) of the Institute for Transuranium Elements (ITU, JRC) was entrusted by DG ENER to design and implement equipment in order to achieve enhanced safeguards of a plutonium dioxide storage located on the MAGNOX reprocessing plant in Sellafield (UK). Enhanced safeguards must lead to a win-win situation for all parties involved. In this case the DG ENER inspectorate will save inspection time, manpower and future financial resources and the operator will have the right to access its storage without the need for inspector presence. To reach this goal, while at the same time taking into account current budget constraints, NUSEC developed applications that use equipment commonly used in the safety and security fields but so far have not been used in safeguards. For instance, two laser scanners are used to detect entry/exit events into and out of the store and to provide the necessary information to an algorithm in order to categorize objects/people passing the scanners, e.g., a Fork Lift Truck, a trolley used to bring in PuO 2 containers, a system used for the dispatch of cans, people, etc. An RFID reader is used to identify equipment duly authorized to access the store. All PuO 2 containers arriving from the production line must be weighed, identified and measured using gamma and neutron detectors before they can be transferred to the store. For this purpose an Unattended Combined Measurement System (UCMS) was designed and manufactured by the JRC in order to do all verification activities using a single instrument. This paper describes the design features of the equipment and its implementation with the support of the Sellafield Ltd. in the framework of the MAGNOX store project. (author)

Magnesium and related low alloys

Energy Technology Data Exchange (ETDEWEB)

Bernard, J; Caillat, R; Darras, R [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1959-07-01

In the first part the authors examine the comparative corrosion of commercial magnesium, of a magnesium-zirconium alloy (0,4 per cent {<=} Zr {<=} 0,7 per cent) of a ternary magnesium-zinc-zirconium alloy (0,8 per cent {<=} Zn {<=} 1,2 per cent) and of english 'Magnox type' alloys, in dry carbon dioxide-free air, in damp carbon dioxide-free air, and in dry and damp carbon dioxide, at temperatures from 300 to 600 deg. C. In the second part the structural stability of these materials is studied after annealings, of 10 to 1000 hours at 300 to 450 deg. C. Variations in grain after these heat treatments and mechanical stretching properties at room temperature are presented. Finally various creep rate and life time diagrams are given for these materials, for temperatures ranging from 300 to 450 deg. C. (author) [French] Dans une premiere partie les auteurs etudient la corrosion comparee du magnesium commercial, d'un alliage magnesium-zirconium (0,4 pour cent {<=} Zr {<=} 0,7 pour cent), d'un alliage ternaire magnesium-zinc-zirconium (0,8 pour cent {<=} Zn {<=} 1,2 pour cent), et d'alliages anglais 'type Magnox', dans l'air sec decarbonate, l'air humide decarbonate, le gaz carbonique sec et humide a des temperatures de 300 a 600 deg. C. Dans une seconde partie, est etudiee la stabilite structurale de ces materiaux apres des recuits de 300 a 450 deg. C, et de 10 a 1000 heures. Sont presentees les variations, apres ces traitements thermiques, de la grosseur du grain, et des caracteristiques mecaniques de traction a la temperature ambiante. Enfin, quelques diagrammes de vitesse de fluage et de durees de vie sont presentes sur ces materiaux pour des temperatures variant entre 300 et 450 deg. C. (auteur)

Factors determining the UK's back-end nuclear fuel cycle strategy and future nuclear systems

International Nuclear Information System (INIS)

Dunn, M.J.; Ainsworth, Z.E.

2002-01-01

Nuclear generating capacity in the UK is static with no units currently under construction. The AGRs and the UK's only PWR, Sizewell B, are operated by British Energy Generation Ltd (BEGL) and British Energy Generation (UK) Ltd (BEG(UK)L), who are subsidiaries of British Energy plc (BE) which was privatised in July 1996. Ownership of the Magnox stations, which were excluded from this privatisation, has now been transferred to BNFL.Government policy on spent fuel management in the UK is that it is for the owners of the spent fuel to decide on the appropriate spent fuel management options, based on their own commercial judgement, subject to meeting the necessary regulatory requirements. The main factors which have predominantly determined UK utility decisions on spent fuel management, to date, have been based on the technical considerations of the spent fuel characteristics, economic attractiveness of the options and at reactor site spent fuel storage capacities. To date, reprocessing has been the dominant form of spent fuel treatment in the UK. Spent fuel storage facilities consist of a mixture of at-reactor stores and large, centralised ponds associated with the reprocessing activities which take place at the Sellafield site. BEGL and BEG(UK)L have contracts for the lifetime arisings of AGR fuel which allow for all AGR spent fuel to be sent to Sellafield for reprocessing or long-term storage. The prompt reprocessing of all Magnox fuel will continue, and spent PWR fuel will continue to be stored at the reactor site in the short to medium term. It is likely that a combination of factors, which are discussed later in this paper, will continue to affect back-end nuclear fuel cycle strategy and future nuclear systems. (author)

A preliminary assessment of polymer-modified cements for use in immobilisation of intermediate level radioactive waste

International Nuclear Information System (INIS)

Burnay, S.G.; Dyson, J.R.

1982-11-01

A range of polymer-modified cements has been examined as candidate materials for the immobilisation of intermediate level radioactive waste. The waste streams studied were inactive simulates of real wastes and included ion-exchange resins, Magnox debris and dilute sludges. Preliminary experiments on the compatibility of the polymer-cement-waste combinations have been carried out and measurements of flexural strength before and after #betta#-irradiation to 10 9 rad and water immersion have been made. Soxhlet leach tests have been used to compare the leach rates of the different materials. From the results of these preliminary experiments, a limited number of polymer-modified cements have been suggested as suitable for more detailed study. (author)

Hot dewatering and resin encapsulation of intermediate level radioactive waste

International Nuclear Information System (INIS)

Rickman, J.; Birch, D.

1985-01-01

The chemistry of the processes involved in the hot dewatering and encapsulation of alumino-ferric hydroxide floc in epoxide resin have been studied. Pretreatment of the floc to reduce resin attack and hydrolysis and to increase the dimensional stability of the solidified wasteform has been evaluated. It has been demonstrated that removal of ammonium nitrate from the floc and control of the residual water in the resin are important factors in ensuring dimensional stability of the solidified resin. Resin systems have been identified which, together with the appropriate waste pretreatment have successfully encapsulated a simulated magnox sludge producing a stable wasteform having mechanical and physical properties comparable with the basic resin. (author)

Click - nuclear energy

International Nuclear Information System (INIS)

1986-01-01

The activities of British Nuclear Fuels are listed, explained and illustrated. It offers a complete cycle from uranium enrichment, fuel manufacture and transport, to fuel reprocessing and radioactive waste management. The uranium fission process is explained as are the basic principles of Magnox and Advanced Gas Cooled Reactors. BNFL's head office is at Risley in Cheshire and it has sites at Capenhurst (uranium enrichment plant), Springfields (fuel manufacturing plant) and Sellafield (fuel reprocessing plant). It owns Calder Hall and Chapelcross nuclear power stations. Safety is a major consideration and strict safety regulations are observed at all sites. BNFL also encourages public interest in its activities. This booklet is part of its public information effort. (U.K.)

Radioactive lobsters put squeeze on Sellafield

Energy Technology Data Exchange (ETDEWEB)

Anon.

1996-11-01

British Nuclear Fuels is facing a new controversy over its Sellafield Works in Cumbria. Levels of the radioactive isotope technetium-99 in lobsters close to the works have risen 40-fold since 1993 -and now far exceed EC standards for contamination of food after a nuclear accident. Radioactive doses to local seafood consumers have been rising steeply since BNFL commissioned a new enhanced actinide removal plant (EARP) in 1994. The Environment Agency has now asked BNFL to consider ways of reducing technetium-99 discharges from the plant - but the company is also under pressure to maintain throughput to meet the safety concerns of the Nuclear Installations Inspectorate (NII) and avoid disrupting the reprocessing of spent Magnox reactor fuel. (UK).

Radioactive lobsters put squeeze on Sellafield

International Nuclear Information System (INIS)

Anon.

1996-01-01

British Nuclear Fuels is facing a new controversy over its Sellafield Works in Cumbria. Levels of the radioactive isotope technetium-99 in lobsters close to the works have risen 40-fold since 1993 -and now far exceed EC standards for contamination of food after a nuclear accident. Radioactive doses to local seafood consumers have been rising steeply since BNFL commissioned a new enhanced actinide removal plant (EARP) in 1994. The Environment Agency has now asked BNFL to consider ways of reducing technetium-99 discharges from the plant - but the company is also under pressure to maintain throughput to meet the safety concerns of the Nuclear Installations Inspectorate (NII) and avoid disrupting the reprocessing of spent Magnox reactor fuel. (UK)

Licensing aspects of structural integrity

International Nuclear Information System (INIS)

Turner, M.J.; Hemsworth, B.; Boydon, F.M.D.; Harrop, L.P.; Waters, R.

1992-01-01

Examples are given of the wide variety of structural integrity assessments of nuclear plant carried out by the United Kingdom Nuclear Installations Inspectorate (NII) and the consequent need for a flexible approach within the framework provided by the Safety Assessment Principles. The paper describes the use of the Special Case Procedure and draws the distinction between the assessment of incredibility of failure of components and components whose failures are considered within the design basis. Assessment examples provided are the Sizewell B reactor pressure vessel, Magnox reactor pressure vessels, the Prototype Fast Reactor core support structure, Advanced Gas-cooled Reactor steam plant, Thermal Oxide Reprocessing Plant (THORP) vessels, and Steam Generating Heavy Water Reactor pressure tubes. (author)

Recent advances in the TIG welding process and the application of the welding of nuclear components

International Nuclear Information System (INIS)

Lucas, W.; Males, B.O.

1982-01-01

Recent advances in the field of precision arc welding techniques and infacilities for production of nuclear power plant components arc presented. Of the precision welding techniques, pulsed TIG welding, pulsed plasma arc welding, hot-wire TIG welding, and pulsed inert-gas metal-arc welding. In the field of weld cladding, GMA plasma welding is cited as an alternative to submerged-arc welding with a strip electrode. Transistors and computer-controlled welding systems get a special mention. Applications of TIG welding in the UK are cited, e.g. welding of components for the AGR nuclear power plant and construction of equipment for repair work in feedwater pipes of the MAGNOX reactor. (orig.) [de

Chemical and hydrothermal studies on once through boilers using a full scale replica

International Nuclear Information System (INIS)

Penfold, D.; Gill, G.M.; Greene, J.C.; Harrison, G.S.; Walker, M.A.

1987-01-01

The paper describes the scope of research work carried out on once through boilers on the test rig at Wythenshawe, United Kingdom. The latter rig was designed and built to replicate the chemical, metallurgical and hydrothermal conditions on single tube test sections of Heysham 1 (AGR) and Wylfa (Magnox) boilers. A description is given of the rig, along with the facilities for obtaining the research data. Research studies on the once through boilers include: Heysham 1 boiler inlet, oxygen stress corrosion risk in post trip operation, Wylfa two phase erosion-corrosion risk in post trip operation, Wylfa two phase erosion-corrosion, dryout phenomena in a helical coil, and heat transfer co-efficients. (UK)

Operating experience at Scottish Nuclear's power stations

International Nuclear Information System (INIS)

Blackburn, P.

1991-01-01

A brief history is presented of the design and operation of the four Scottish nuclear power stations currently run by Scottish Nuclear, namely Hunterston 'A' and 'B' and the Torness reactors. A design flaw in the Magnox reactor at Hunterston 'A' led to it being operated at lower than optimal temperature and hence producing less power. For Hunterston 'B' reactor the Advanced Gas Cooled design prototype was used. Operating setbacks and successes are noted. The design chosen for Torness embraced all the good points of Hunterston 'B' but sought to eliminate its faults. After 26 years of successful operation Hunterston 'A' is now being decommissioned, while the other three stations continue to generate electricity successfully. (UK)

A Review of the United Kingdom Fast Reactor Programme, March 1987

International Nuclear Information System (INIS)

Bramman, J.I.; Wheeler, R.C.

1987-01-01

Nuclear power produced about 20% of the electricity supply in the United Kingdom in 1986, mostly from gas-cooled reactors, i.e. the 10 AGRs currently in operation and the 26 older MAGNOX reactors. Plans to increase the nuclear component of generating capacity by building the first PWR in the UK, Sizewell 'B', were strongly endorsed in the report by Sir Frank Layfield published on 26 January 1987. This resulted from the Public Inquiry into building Sizewell 'B', which was held between 11 January 1983 and 7 March 1985, the longest Public Inquiry ever held in the UK. The government gave the go-ahead for the building of Sizewell 'B' on 12 March 1987

EDF energy generation UK transport of irradiated fuel

Energy Technology Data Exchange (ETDEWEB)

James, R. [EDF Energy, London, (United Kingdom)

2015-07-01

This paper give an overview of irradiated fuel transport in the UK. It describes the design of irradiated fuel flask used by EDF Energy; operational experience and good practices learnt from over 50 years of irradiated fuel transport. The AGRs can store approximately 9 months generation of spent fuel, hence the ability to transport irradiated fuel is vital. Movements are by road to the nearest railhead, typically less than 2 miles and then by rail to Sellafield, up to 400 miles, for reprocessing or long term storage. Road and rail vehicles are covered. To date in the UK: over 30,000 Magnox flask journeys and over 15,000 AGR A2 flask journeys have been carried out.

Temperature coefficients in the Dragon low-enriched power reactor

Energy Technology Data Exchange (ETDEWEB)

Hansen, U

1972-05-15

The temperature coefficient of the fuel and of the moderator have been evaluated for the Dragon HTR design for different stages in reactor life, initial core, end of no-refuelling period and equilibrium conditions. The investigation has shown the low-enriched HTR to have a strong, positive moderator coefficient. In some cases and for special operating conditions, even leading to a positive total temperature coefficient. This does not imply, however, that the HTR is an unsafe reactor system. By adequate design of the control system, safe and reliable operating characteristics can be achieved. This has already been proved satisfactory through many years of operation of other graphite moderated systems, such as the Magnox stations.

Options for Enhancing Education, Training and Knowledge Management for Decommissioning

International Nuclear Information System (INIS)

Roberts, John

2017-01-01

UK Nuclear Sites: Decommissioning: 26 Magnox Reactors, 2 Fast Reactors; Operational: 14 AGRs, 1 PWR; 9.6 GWe Total Capacity. Nuclear Technology Education Consortium (NTEC) Decommissioning Modules: N04 Decommissioning, Radioactive Waste and Environmental Management; N07 Nuclear Safety Case Development; N08 Particle & Colloid Engineering in the Nuclear Industry; N09 Policy, Regulation & Licensing; N10 Processing, Storage & Disposal of Nuclear Waste; N31 Management of the Decommissioning Process; N01 Reactor Physics, Criticality & Design; N02 Nuclear Fuel Cycle; N03 Radiation & Radiological Protection; N06 Reactor Materials & Lifetime Behaviour; N11 Radiation Shielding; N12 Reactor Thermal Hydraulics; N13 Criticality Safety Management; N23 Environmental Impact Assessment; N32 Experimental Reactor Physics

Immobilization of radioactive waste in cement-based matrices

International Nuclear Information System (INIS)

Glasser, F.P.; Rahman, A.A.; Crawford, R.W.; McCulloch, C.E.; Angus, M.J.

1984-01-01

Tobermorite and xonotlite, two synthetic calcium silicate hydrates, improve the Cs retention of cement matrices for Cs, when incorporated at the 6 to 10% level. A kinetic and mechanistic scheme is presented for the reaction of fine grained, Cs-loaded clinoptilolite with cement. The Magnox waste form reacts quickly with cement, leading to an exchange of carbonate between waste form and cement components. Carbonation of cements leads to a marked improvement in their physical properties of Cs retentivity. Diffusion models are presented for cement systems whose variable parameters can readily be derived from experimental measurements. Predictions about scaled-up behaviour of large immobilized masses are applied to extrapolation of laboratory scale results to full-size masses. (author)

The export of weapons grade plutonium to the USA

International Nuclear Information System (INIS)

Kollerstrom, N.

1986-01-01

Reprocessed spent Magnox fuel from British nuclear power plants has led, it is claimed, to the production of plutonium, some of weapons grade. Some of this has been exported to the USA where, it is assumed, it is used for military purposes. The route and agreements which make this possible and the quantities involved are reported. Inspection by IAEA is insufficient to check the Central Electricity Generating Board's (CEGB) claim that no CEGB plutonium has been used for a military purpose. The CEGB case, presented at the Sizewell Inquiry is discussed. In the United States it is not clear whether plutonium from Britain, at present in a civil stockpile, will be transferred to military use or not. (U.K.)

Estimating and comparing risks in the future

International Nuclear Information System (INIS)

Llewellyn, Gareth

1998-01-01

The current position of power generation in UK is balanced. Recently 16 advanced gas cooled reactors are in operation. Privatisation of most power generation plants is done. Some trialing of environmental premia is performed. Environmental management is very strong. Nuclear power status in the UK is as follows: 16 Advanced gas cooled reactors, 1 Pressurised water reactor, Nuclear Electric/Scottish Nuclear in commercial operation; out of 18 Magnox reactors in operation 3 are decommissioned, 8 are due to stop operating before 2000. Non-nuclear fuel used are coal, oil, gas, hydropower. Besides carbon dioxide emissions emerging issue is rad waste disposal. This presentation deals with the strategic risk assessment in power generation sector

Dealing with operational power station wastes

Energy Technology Data Exchange (ETDEWEB)

Pepper, R B [Central Electricity Generating Board, London (UK). Nuclear Health and Safety Dept.

1981-08-01

The disposal of wastes from nuclear power stations is discussed. Liquid and gaseous wastes, from magnox stations, which are of low level activity, are dispersed to the sea or estuaries on coastal sites or for the case of Trawfynyeld, to the nearby lake. Low activity solid wastes are either disposed of on local authority tips or in shallow land burial sites. Intermediate level wastes, consisting mainly of wet materials such as filter sludges and resins from cooling ponds, are at present stored in shielded storage tanks either dry or under water. Only one disposal route for intermediate waste is used by Britain, namely, sea-dumping. Materials for sea dumping have to be encapsulated in a durable material for example, concrete.

The transport implications of regional policies for the disposal of intermediate level radioactive wastes

International Nuclear Information System (INIS)

James, I.A.

1985-09-01

This report aims to evaluate transport parameters and logistics associated with the disposal of intermediate-level radioactive wastes, as generated by CEGB, SSEB, UKAEA and BNFL. The assumed power scenario is DoE Scheme 3, which approximates to a moderate power generation scenario, with a 15 GWe PWR programme commissioned between 1991 and 2010, existing Magnox and AGR stations are assumed to have a 30 year lifespan. Three transport options are again assumed, namely; road, rail and a hybrid system, as is consistent with previous studies. These three options will be used in investigating regional policies of disposal, initially at the national level and then progressively disaggregating to a system of three regional depositories serving their respective catchment areas. (author)

A microstructural study of dynamic crack propagation in nuclear graphites

International Nuclear Information System (INIS)

Burchell, T.D.; McEnaney, B.; Tucker, M.O.; Rose, A.P.G.

1986-01-01

This paper reports a new microstructural study of dynamic crack propagation in three nuclear graphites: (i) PGA, the moderator material in UK Magnox reactors; (ii) IMl-24, the moderator material in UK Advanced gas cooled reactors (AGR); and (iii) a pitch coke graphite, which is used in the fabrication of AGR fuel sleeves. The fracture mechanisms in nuclear graphites are initiated by microcrack formation at low stresses. Typically, microcracks form in regions of well-aligned binder or at favourably-oriented pores, where stress is concentrated. With increasing applied loads, microcracks propagate taking advantage of easy cleavage paths or linking with pores. Eventually, coalescence of such cracks and inherent porosity produces a crack of critical length for fast fracture. (orig./MM)

Construction gets underway on Hungary's Modern Vault Dry Store

International Nuclear Information System (INIS)

Anon.

1995-01-01

A construction licence has recently been granted for a Modular Vault Dry Store (MVDS) for spent fuel at the Paks reactor site in Hungary. The store will be used for medium term (50 years) storage of spent fuel from four VVER-440 reactors. It is anticipated that storage capacity for 1350 fuel assemblies will be available by 1996. Two further construction phases will take the capacity to 4950, covering the first ten years of reactor operation. The design provides for further extension to accommodate a total 15000 assemblies, corresponding to 30 years of reactor operation. The MVDS has developed out of the first application of dry store technology to spent Magnox reactor fuel at the Wylfa power station in the United Kingdom 25 years ago. (UK)

Planning and progress of the WAGR decommissioning project

International Nuclear Information System (INIS)

Boorman, T.

1988-01-01

In the United Kingdom, the earliest production reactors, which will be decommissioned first, are of the Magnox type. The Windscale Advanced Gas-cooled Reactor, is however, sufficiently similar to make it a suitable prototype decommissioning project. The planning and progress so far is described. Special decommissioning equipment, including a remote dismantling machine, has been developed and a waste packaging building built on site. Its function is to enable all intermediate-level and low-level radioactive waste removed from the reactor vault by remote equipment to be packaged remotely into suitable containers. The work done on the WAGR decommissioning has shown that the dismantling of a power-producing reactor is feasible and can be accomplished using existing engineering techniques. (U.K.)

Annual report and accounts [1992-1993

International Nuclear Information System (INIS)

1994-01-01

Uncertainty over the future of nuclear power and delay in gaining discharge authorisations for the Thermal Oixde Reprocessing Plant (THORP) affected the financial results, with profits down to Pound 76 million whilst turnover has also down to Pound 1049 million. This annual report was also delayed by 6 months whilst the delays to THORP were resolved. Failure to finalise important contracts covering the fixed price arrangements agreed with Nuclear Electric and Scottish Nuclear also caused poorer financial results and frustration. The third factor which reduced profits was the failure of an evaporator at the magnox reprocessing plant at Sellafield which caused its closure for 7 weeks. The company's operations are summarised and its policies stated. Detailed accounts are presented. (UK)

Removal of 14C from Irradiated Graphite for Graphite Recycle and Waste Volume Reduction

International Nuclear Information System (INIS)

Dunzik-Gougar, Mary Lou; Windes, Will; Marsden, Barry

2014-01-01

The aim of the research presented here was to identify the chemical form of 14 C in irradiated graphite. A greater understanding of the chemical form of this longest-lived isotope in irradiated graphite will inform not only management of legacy waste, but also development of next generation gas-cooled reactors. Approximately 250,000 metric tons of irradiated graphite waste exists worldwide, with the largest single quantity originating in the Magnox and AGR reactors of UK. The waste quantity is expected to increase with decommissioning of Generation II reactors and deployment of Generation I gas-cooled, graphite moderated reactors. Of greatest concern for long-term disposal of irradiated graphite is carbon-14 14 C, with a half-life of 5730 years.

Comparing nuclear decommissioning in the UK and France

International Nuclear Information System (INIS)

Walls, J.; Garcier, R.

2008-01-01

In this paper we will compare the decommissioning policies in the UK and France. Both countries have a long nuclear history and decommissioning has taken place since the 1960. However, the proposed decommissioning of Magnox and AGR sites in the UK and of UNGG sites in France brings decommissioning efforts to a new level. Whilst we explore in detail the approaches and methodologies adopted in each country we remain sensitive to the effects that political and economic history play in shaping the policy response. In this paper we draw upon interviews conducted with a range of key stakeholders including: national regulators, companies involved in decommissioning, local politicians and community representatives. We also analyse key academic and non academic literature. (authors)

Computer-based training at Sellafield

International Nuclear Information System (INIS)

Cartmell, A.; Evans, M.C.

1986-01-01

British Nuclear Fuel Limited (BNFL) operate the United Kingdom's spent-fuel receipt, storage, and reprocessing complex at Sellafield. Spent fuel from graphite-moderated CO 2 -cooled Magnox reactors has been reprocessed at Sellafield for 22 yr. Spent fuel from light water and advanced gas reactors is stored pending reprocessing in the Thermal Oxide Reprocessing Plant currently being constructed. The range of knowledge and skills needed for plant operation, construction, and commissioning represents a formidable training requirement. In addition, employees need to be acquainted with company practices and procedures. Computer-based training (CBT) is expected to play a significant role in this process. In this paper, current applications of CBT to the filed of nuclear criticality safety are described and plans for the immediate future are outlined

United Kingdom and USSR reactor types

International Nuclear Information System (INIS)

Lewins, Jeffery

1988-01-01

The features of the RBMK reactor operated at Chernobyl are compared with reactor types pertinent to the UK. The UK reactors covered are in three classes: the commercial reactors now built and operated or in commission (Magnox and Advanced Gas-cooled Reactor (AGR)); the prototype Steam Generating Heavy Water Reactor (SGHWR) and Prototype Fast Reactor (PFR) that have comparable performance to commercial reactors; and the proposed Pressurised Water Reactor (PWR) or Sizewell 'B' design which, it will be recollected, is different in detail from PWRs built elsewhere. We do not include research and test reactors nor the Royal Navy PWRs. The appendices explain resonances, Doppler and Xenon effects, the reactor physics of Chernobyl and positive void coefficients all of which are relevant to the comparisons. (author)

An international benchmark on safety review practices at nuclear power plants

International Nuclear Information System (INIS)

Wahlstroem, B.; Kettunen, J.

2000-02-01

A benchmarking exercise on safety review practices at nuclear power plants in Finland, Sweden and the United Kingdom has been carried out. In the exercise a comparison was made between documented practices at the Forsmark, Hinkley Point A and Olkiluoto nuclear power plants. In addition a total of 28 persons at FKA, Magnox and TVO were interviewed on their views on the efficiency of the plant modification processes in the later half of 1997. One specific example of a plant modification was selected from each of the nuclear power plant sites to provide a basis for the comparison. The report gives an account of the methodology used, a description of the plant modification projects, impressions from the interviews, potential problem areas and suggestions for possible improvements. (orig.)

Conditioning of alpha waste

International Nuclear Information System (INIS)

Halaszovich, S.; Gerontopoulos, P.; Hennart, D.; Ledebrink, F.W.; Loida, A.; Phillips, D.C.; Vandevoorde, N.

1985-01-01

The long life and high radiotoxicity of the alph-emitting transuranics in radioactive waste provide an incentive for the constant improvement of existing processes and waste forms or the development of new alternatives, to isolate them safely from the biosphere. In the following, five processes at differing stages of development are outlined, the products ranging between cement, glass and ceramics: a process developed by ALKEM for the cementation of waste from fuel element manufacture; a process to improve the quality of cement products containing Magnox hulls, under development at AERE Harwell; high-temperature slagging incineration, developed at SCK/CEN; embedding of waste in an alumosilicate-based ceramic, being developed at KfK; embedding of waste in a titanium dioxide-based ceramic, proposed by Agip

Control of radiocaesium discharges to the Irish Sea: ICRP-26 in practice

International Nuclear Information System (INIS)

Handyside, I.; Hunt, G.J.; Partington, C.

1982-01-01

Experience of application of the ICRP dose limitation system is described in the context of control of radioactive waste discharges to the north-east Irish Sea from the British Nuclear Fuels Limited (BNFL) Sellafield Works. The radiological significance of these discharges is mainly due to radiocaesium from the magnox fuel storage ponds. The discharges increased in 1974 owing to corrosion of magnox fuel; radiation exposure of the public mainly through the fish and shellfish consumption pathway also increased. BNFL, in consultation with Government Departments, decided to install an ion-exchange treatment plant to remove radioactivity from pond effluents. This plant is presently being built and will provide a long-term reduction in radiocaesium discharges. Optimization will play a major part in determining its operating regime. Meanwhile, measures to reduce discharges have been taken by circulating pond water through skips of zeolite installed in the ponds. Differential cost-benefit analysis has been used to indicate the optimum replacement rate of skips; experience of this is described. A range of skip costs was used to allow for some factors which were not uniquely definable. Detrimental costs were estimated from collective dose commitments and a range of values of the man-Sv from Pound 2000 to Pound 50,000. Other, non-quantifiable, factors were relevant. Following these considerations, the current skip replacement frequency is about 30 year -1 . Skips are presently reducing collective effective dose equivalent commitments to the UK and European populations by about half, or some 150 man-Sv.year -1 . Finally, to demonstrate conformity with the overall ICRP dose limitation system, compliance with dose limits is described. Effective dose equivalents to the relevant critical groups for the years 1977 to 1980 are presented. The use of zeolite skips has, here too, given significant reductions over this time, from 33% to (provisionally) 15% of the ICRP-recommended dose

Annual report and accounts 1989/90

International Nuclear Information System (INIS)

1990-01-01

When the government decided to privatise the electricity generating industry it was decided to retain nuclear generation in the public sector. Thus, Scottish Nuclear Ltd, formerly part of the South of Scotland Electricity Boeard, was created in March 1990. Scottish Nuclear owns and is responsible for the continued safe and commercially sound operation of two nuclear power stations, Hunterston 'B' on the Firth of Clyde and Torness on the Scottish east coast. Both are Advanced Gas Cooled Reactors. The company is also responsible for Hunterston 'A', a Magnox power station; both the Hunterston 'A' reactors have been shut down on economic grounds. This, the company's first Annual Report, includes the Chairman's statement, Chief Executive's review, a summary of the activities, a list of Directors and advisers, the Directors' report and the accounts. (UK)

United Kingdom national report

International Nuclear Information System (INIS)

Tomkins, B.

1998-01-01

Report of the United Kingdom deals with life extension granted to Calder Hall and Chapelcross reactors for further 10 years operation. The two well recognised life-limiting features of Magnox type reactors are graphite core ageing and materials properties of the reactor pressure circuit components. These features have been scrutinised particularly closely and the conclusion has been reached that there are no safety factors which will necessarily limit the plant life to less than 50 years. Two other life-limiting factors are hear exchanger tubes and the heat exchanger tube failures internal to boiler shells and the integrity of the main engineering structures of the plant. It was concluded that appropriate routine ageing monitoring programs are in place in respect to these features to support continuing operation beyond 40 years

Demonstrating the capability and reliability of NDT inspections

International Nuclear Information System (INIS)

Wooldridge, A.B.

1996-01-01

This paper discusses some recent developments in demonstrating the capability of ultrasonics, eddy currents and radiography both theoretically and in practice, and indicates where further evidence is desirable. Magnox Electric has been involved with development of theoretical models for all three of these inspection methods. Feedback from experience on plant is also important to avoid overlooking any practical limitations of the inspections, and to ensure that the metallurgical characteristics of potential defects have been properly taken into account when designing and qualifying the inspections. For critical applications, inspection techniques are often supported by a Technical Justification which draws on all the relevant theoretical and experimental evidence, as well as experience of inspections on plant. The role of technical justifications is discussed in the context of inspection qualification. (author)

Design and development of steam generators for the AGR power stations at Heysham II/Torness

Energy Technology Data Exchange (ETDEWEB)

Charcharos, A N; Jones, A G [National Nuclear Corp. Ltd., Cheshire (United Kingdom)

1984-07-01

The current AGR steam generator design is a development of the successful once-through units supplied for the Oldbury Magnox and Hinkley/Hunterston AGR power stations. These units have demonstrated proven control and reliability in service. In this paper the factors which have dictated the design and layout of the latest AGR steam generators are described and reference made to the latest high temperature design techniques that have been employed. Details of development work to support the design and establish the performance characteristics over the range of plant operating conditions are also given. To comply with current UK safety standards, the AGR steam generators and associated plant are designed to accommodate seismic loadings. In addition, provision is made for an independent heat removal system for post reactor trip operations. (author)

Session 1984-85. Radioactive waste. Minutes of evidence, Wednesday 23 October 1985. Department of the Environment

International Nuclear Information System (INIS)

1985-01-01

The Environment Select Committee of the House of Commons received a memorandum from the Department of the Environment on radioactive waste and reprocessing, under the headings: long-term management of spent fuel; comparison of wastes arising from reprocessing and storage/disposal of spent fuel; the spent fuel assemblies; waste arising from spent-fuel management at reactor sites; reprocessing wastes; long-term storage and direct disposal of spent fuel; liquid and gaseous discharges; CEGB note on the drying-off and subsequent long term storage of spent magnox fuel. The Minister of the Environment and representatives of the Department of the Environment were examined on the subject of the memorandum. The problems of finding sites suitable for radioactive waste storage/disposal and acceptable to public opinion were discussed. (U.K.)

Graphics and control for in-reactor operations

International Nuclear Information System (INIS)

Smith, A.L.

1996-01-01

A wide range of manipulator systems has been developed to carry out remotely operated inspection, repair and maintenance tasks at the Magnox reactors in the United Kingdom. A key factor in the improvement of these systems in recent years has been the extensive use of computer graphics as a real-time aid to the manipulator operator. This is exemplified by the reactor pressure vessel inspection work at the Bradwell reactor which is described in detail. The graphics sub-system of the control system for the manipulator plays a unique and wide-ranging role. The 3D modelling and simulation capability of the IGRIP software has contributed to the conceptual design, detailed path planning, rehearsal support, public relations, real-time manipulator display, post inspection documentation and quality assurance. (UK)

Operating experience of vault type dry storage and its relevance to future storage needs

International Nuclear Information System (INIS)

Maxwell, E.O.; Deacon, D.

1982-01-01

An outline description of the early passive cooled vault type dry stores for irradiated magnox fuel at the Wylfa Nuclear Power Station together with the valuable operating experience gained over many years. An outline description of the world's first air-cooled vault type dry store (350 Te) and comments on its construction and successful operation. A description of the basic principles that were used in the design of this store and how these principles have been developed for use on vault type storage systems for oxide fuel and vitrified waste. An examination of the basic parameters that the author's consider should be used to measure the adequacy of the many storage options currently being considered around the world is included in order that a better assessment of the various systems may be obtained

Quality checking of radioactive and hazardous waste

International Nuclear Information System (INIS)

Billington, D.M.; Burgoyne, S.M.J.; Dale, C.J.

1992-01-01

This report describes the work of the HMIP Waste Quality Checking Laboratory (WQCL) for the period September 1989 -August 1991. The WQCL has conducted research and development of procedures for the receipt, sampling and analysis of low level solid radioactive waste (LLW), intermediate level radioactive waste (ILW) and hazardous chemical waste (HW). Operational facilities have been commissioned for quality checking both LLW and HW. Waste quality checking has been completed on LLW packages seized from the UK waste disposal route by HMIP Inspectors. Packages have ranged in size from the 200 litre steel drum to half-height ISO freight container. Development work was continued on methods of sample extraction and radio-chemical analysis for cement encapsulated ILW in the form of magnox, graphite and stainless steel. This work was undertaken on non-radioactive simulants. (author)

Temperature measurement of the reactor materials samples irradiated in the fuel channels of the RA reactor - Annex 16

International Nuclear Information System (INIS)

Nikolic, M.; Djalovic, M.

1964-01-01

Reactor materials as graphite, stainless steel, magnox, zirconium alloys, etc. were exposed to fast neutron flux inside the fuel elements specially adapted for this purpose. Samples in the form ampoules were placed in capsules inside the fuel channels and cooled by heavy water which cools the fuel elements. In order to monitor the samples temperature 42 thermocouples were placed in the samples. That was necessary for reactor safety reasons and for further interpretation of measured results. Temperature monitoring was done continuously by multichannel milivoltmeters. This paper describes the technique of introducing the thermocouples, compensation instruments, control of the cold ends and adaptation of the instruments for precision (0.5%) temperature measurement in the range 30 deg - 130 deg C; 30 deg - 280 deg C and 30 deg - 80 deg C [sr

UK Nuclear Workforce Demand

International Nuclear Information System (INIS)

Roberts, John

2017-01-01

UK Nuclear Sites: DECOMMISSIONING - 26 Magnox Reactors, 2 Fast Reactors; OPERATIONAL - 14 AGRs, 1 PWR; 9.6 GWe Total Capacity. Nuclear Workforce Demand • Total workforce demand is expected to grow from ~88,000 in 2017 to ~101,000 in 2021 • Average “inflow” is ~7,000 FTEs per annum • 22% of the workforce is female (28% in civil, 12% in defence) • 81% generic skills, 18% nuclear skills, 1% subject matter experts • 3300 trainees total in SLCs and Defence Enterprise (16% graduate trainees) • At peak demand on Civils Construction, over 4,000 workers will be required on each nuclear new build site • Manufacturing workforce is expected to rise from around 4,000 in 2014 to 8,500 at the peak of onsite activity in 2025

Power station impacts: socio-economic impact assessment

International Nuclear Information System (INIS)

Glasson, John; Elson, Martin; Barrett, Brendan; Wee, D. Van der

1987-01-01

The aim of this study is to assess the local social and economic impacts of a proposed nuclear power station development at Hinkley Point in Somerset. The proposed development, Hinkley Point C, would be an addition to the existing Hinkley Point A Magnox station, commissioned in 1965, and the Hinkley Point B Advanced Gas Cooled Reactor (AGR) station, commissioned in 1976. It is hoped that the study will be of assistance to the CEGB, the Somerset County and District Councils and other agencies in their studies of the proposed development. In addition, the study seeks to apply and further develop the methodology and results from previous studies by the Power Station Impacts (PSI) team for predicting the social and economic effects of proposed power station developments on their localities. (author)

Specific problems and practical experience of regulatory inspection during commissioning in the United Kingdom

International Nuclear Information System (INIS)

Lewis, G.

1977-01-01

The commissioning of nine Magnox and two Advanced Gas-cooled Reactor Nuclear Power Plants in the United Kingdom during the last sixteen years under the regulatory control of the Nuclear Installations Inspectorate of the Health and Safety Executive has been based on a Stage Approval Philosophy starting with proof-testing of the primary gas circuit and concluding with tests on the reactor at full power. The practical experience gained during this period has enabled the Nuclear Installations Inspectorate to rationalise the procedures and test requirements without comporomising safety standards. The Operating Rules and Maintenance Schedules are approved for commissioning and during this period are reviewed for their adequacy for future power operation of the plant. The organisation, documentation, test procedures and the commissioning programme used for the Advanced Gas-cooled Reactors are briefly explained. (author)

A digital joint controller for manipulators

International Nuclear Information System (INIS)

Holt, E.J.; Palmer, D.E.B.

1993-01-01

Nuclear Electric's hydraulic heavy duty manipulators are used at a number of Magnox Power Stations for a wide variety of tasks. In recent years there has been a trend towards the use of manipulators for tasks requiring increasing precision of tip positioning. In order to meet this requirement, a digital controller has been designed to replace the analogue controller board used in almost all manipulator control systems. The new controller allows the programming of a wide range of closed loop control algorithms. Position and drive signal data may be passed to and from the controller by digital means, allowing direct connection to a graphical display system and/or a computer executing a guidance algorithm. The hardware and software design are outlined and performance in the laboratory and the field is reported. (author)

Design and development of steam generators for the AGR power stations at Heysham II/Torness

International Nuclear Information System (INIS)

Charcharos, A.N.; Jones, A.G.

1984-01-01

The current AGR steam generator design is a development of the successful once-through units supplied for the Oldbury Magnox and Hinkley/Hunterston AGR power stations. These units have demonstrated proven control and reliability in service. In this paper the factors which have dictated the design and layout of the latest AGR steam generators are described and reference made to the latest high temperature design techniques that have been employed. Details of development work to support the design and establish the performance characteristics over the range of plant operating conditions are also given. To comply with current UK safety standards, the AGR steam generators and associated plant are designed to accommodate seismic loadings. In addition, provision is made for an independent heat removal system for post reactor trip operations. (author)

Recent UK Experience of Involving the Public in Decisions on Radioactive Discharges

International Nuclear Information System (INIS)

Smith, R.E.; Weedon, C.J.; McGoff, A.; Bower, M.

2001-01-01

In January 1998 BNFL applied to the Agency for authorisations to dispose of gaseous, liquid, combustible and solid radioactive wastes in respect of each of Magnox Electric's power stations. The Agency is currently considering BNFL's applications. This is the first time that authorisations for radioactive waste disposal have been considered for all these stations together as a package. It has been a major task for BNFL to assemble all the relevant information and for the Agency to drive the process forward through public consultation to the decision-making stage. As part of its role of protecting and improving the environment, the Agency is committed to progressive reductions in radioactive discharges where practicable, seeking to achieve this through the limits and conditions of any authorisation it issues. It aims to review nuclear site authorisations on a four-yearly cycle and has used BNFL's applications as the basis for its review of the Magnox power station sites. The Agency carefully scrutinised the applications and obtained additional detailed information and clarification from BNFL in response to six rounds of questions. The applications and responses from the company to Agency questions were made publicly available. They include information on: the benefits and detriments of continued operation/decommissioning (as appropriate); the sources and amounts of radioactive waste associated with continued operation/decommissioning; the current levels of discharge of radioactive waste to the environment; and the application of best practicable means (BPM) to minimise discharges. The Agency is considering all the application information and must decide, separately for each power station, whether an authorisation should be issued to BNFL. It has consulted publicly to assist its decision making, the objective being to enable people and organisations to draw to the Agency's attention any matters they would wish it to consider when reaching its decisions on the

Decommissioning of nuclear power stations

International Nuclear Information System (INIS)

Gregory, A.R.

1988-01-01

In the United Kingdom the Electricity Boards, the United Kingdom Atomic Energy Authority (UKAEA) and BNFL cooperate on all matters relating to the decommissioning of nuclear plant. The Central Electricity Generating Board's (CEGB) policy endorses the continuing need for nuclear power, the principle of reusing existing sites where possible and the building up of sufficient funds during the operating life of a nuclear power station to meet the cost of its complete clearance in the future. The safety of the plant is the responsibility of the licensee even in the decommissioning phase. The CEGB has carried out decommissioning studies on Magnox stations in general and Bradwell and Berkeley in particular. It has also been involved in the UKAEA Windscale AGR decommissioning programme. The options as to which stage to decommission to are considered. Methods, costs and waste management are also considered. (U.K.)

The radioactive inventory of a Berkeley heat exchanger

International Nuclear Information System (INIS)

Hancock, R.

1988-10-01

The Central Electricity Generating Board has announced a date for the final shutdown of the first of the Magnox power stations at Berkeley (March 1989), and is in the process of preparing Pre-Decommissioning Safety Reports (PDSR) for the decommissioning of Berkeley and Bradwell. This report supports these PDSR studies and reports work carried out within the Research Division at Berkeley Nuclear Laboratories on the radioactive inventories of the heat exchangers at Berkeley Power Station. At Berkeley, the heat exchangers will be included in stage two decommissioning to which they will contribute the largest mass of contaminated material. The purpose of this report is to bring together all of the available data on the contamination in the heat exchangers at Berkeley Power Station, and to recommend a database from which the options for disposal of the heat exchangers may be formulated. (author)

Acoustic monitoring techniques for corrosion degradation in cemented waste canisters

International Nuclear Information System (INIS)

Naish, C.C.; Buttle, D.; Wallace-Sims, R.; O'Brien, T.M.

1991-01-01

This report describes work to investigate acoustic emission as a non-intrusive monitor of corrosion and degradation of cemented wasteforms where the waste is a potentially reactive metal. The acoustic data collected shows good correlation with the corrosion rate as measured by hydrogen gas evolution rates and the electrochemically measured corrosion rates post cement hardening. The technique has been shown to be sensitive in detecting stress caused by expansive corrosion product within the cemented wasteform. The attenuation of the acoustic signal by the wasteform reduced the signal received by the monitoring equipment by a factor of 10 over a distance of approximately 150-400 mm, dependent on the water level in the cement. Full size packages were successfully monitored. It is concluded that the technique offers good potential for monitoring cemented containers of the more reactive metals, for example Magnox and aluminium. (author)

The future for nuclear power

International Nuclear Information System (INIS)

Marshall of Goring, Lord.

1989-01-01

Lord Marshall explains how the situation for nuclear power in late 1989 in the United Kingdom had come about. Despite warnings that for a successful nuclear programme a large generator which has the obligation to supply in a defined geographical area should operate, this is not what will happen under the plans to privatise the electricity supply industry in the UK. Under these no body will have the obligation to supply electricity and the distribution Company will not have the obligation to supply after the first few years. Other problems with the privatisation plans are discussed. The implications of the government's decisions on nuclear power, first to maintain the Magnox stations in the government sector, second to abandon the full PWR construction programme and thirdly not to transfer the AGRs to the private sector, are discussed. (UK)

Calculating the plutonium in spent fuel elements

International Nuclear Information System (INIS)

Barnham, Keith

1992-01-01

Many members of the public are concerned about plutonium. They are worried about its environmental, health and proliferation risks. Fundamental to all such considerations are two related questions: how much plutonium do nuclear reactors produce ? and how accurately do the relevant authorities know these production figures ? These two questions have been studied with particular reference to the UK civil Magnox reactors. In 1990 these were still the only UK civil reactors whose spent fuel had been reprocessed to extract plutonium in routine production. It has not been possible to conclude that the relevant government industry and safeguard authorities are aware of how much plutonium these reactors produce and that the figures are known to the highest achievable accuracy. To understand why, this chapter will outline some of the history of the attempts to get answers to these two questions. (author)

Training of engineers for nuclear power station operation

International Nuclear Information System (INIS)

Myerscough, P.B.

1980-01-01

The requirements for staffing and training of a nuclear electric utility are described. Current training facilities at the Central Electricity Generating Board are applicable to gas-cooled technology with the possibility of the introduction of a thermal water system and fast reactors in the future. The CEGB training centres provide for the initial training of operational staff, revision training of experienced operational staff, and training of non-operational staff from the stations and supporting departments. Details are given of the content of the training courses which also provide simulation facilities of the basic dynamics of the CEGB stations. Further developments in simulation will include dynamics of the boiler and turbine plants in Magnox stations. The flexibility of the AGR simulations will enable the training exercises to be adjusted to meet changing operating patterns for each AGR station. (U.K.)

Graphite core design in UK reactors

International Nuclear Information System (INIS)

Davies, M.W.

1996-01-01

The cores in the first power producing Magnox reactors in the UK were designed with only a limited amount of information available regarding the anisotropic dimensional change behaviour of Pile Grade graphite. As more information was gained it was necessary to make modifications to the design, some minor, some major. As the cores being built became larger, and with the switch to the Advanced Gas-cooled Reactor (AGR) with its much higher power density, additional problems had to be overcome such as increased dimensional change and radiolytic oxidation by the carbon dioxide coolant. For the AGRs a more isotropic graphite was required, with a lower initial open pore volume and higher strength. Gilsocarbon graphite was developed and was selected for all the AGRs built in the UK. Methane bearing coolants are used to limit radiolytic oxidation. (author). 5 figs

Acoustic monitoring techniques for corrosion degradation in cemented waste canisters

International Nuclear Information System (INIS)

Naish, C.C.; Buttle, D.; Wallace-Sims, R.; O'Brien, T.M.

1991-01-01

This report describes work carried out to investigate acoustic emission as a monitor of corrosion and degradation of wasteforms where the waste is potentially reactive metal. Electronic monitoring equipment has been designed, built and tested to allow long-term monitoring of a number of waste packages simultaneously. Acoustic monitoring experiments were made on a range of 1 litre cemented Magnox and aluminium samples cast into canisters comparing the acoustic events with hydrogen gas evolution rates and electrochemical corrosion rates. The attenuation of the acoustic signals by the cement grout under a range of conditions has been studied to determine the volume of wasteform that can be satisfactorily monitored by one transducer. The final phase of the programme monitored the acoustic events from full size (200 litre) cemented, inactive, simulated aluminium swarf wastepackages prepared at the AEA waste cementation plant at Winfrith. (Author)

The nuclear review

International Nuclear Information System (INIS)

Jeffrey, R.

1995-01-01

The prospects for nuclear power in the United Kingdom are considered from the point of view of Scottish Nuclear and in the context of the government's Nuclear Review and forthcoming proposals for the future of nuclear generation. Scottish Nuclear has been successful in transforming a loss making public sector company into one which is profitable. If proper account is taken of the risks of higher gas prices, environmental costs and the vulnerability to which the UK energy supply industry might be exposed by over dependence on gas, nuclear power is seen to be attractive. Outcome from the Review which Scottish Nuclear would like to see includes: a separation of their successful ongoing AGR programme from the historical magnox liabilities; a segregated fund to deal with long term AGR decommissioning and waste liabilities; greater commercial freedom and a move towards privatisation. (UK)

α-particle radioactivity of hot particles from the Esk estuary

International Nuclear Information System (INIS)

Hamilton, E.I.

1981-01-01

Transuranium radionuclides (Pu, Am and Cm) present in effluents discharged into the north-east Irish Sea by British Nuclear Fuels Limited, Windscale, Cumbria, UK, are found in sediment and biota of the Esk estuary approximately 10 km to the south. The site of the present investigation was at Newbiggin and the materials examined were suspended particulate debris samples at the sea surface, bottom sediments and some forms of biota collected in September 1977. It is shown here that hot particles (defined as small volumes of material emitting α particles recorded in a dielectric detector as dense clusters of tracks from a common origin) found in the estuary are likely to be original effluent debris derived from the processing of Magnox uranium fuel elements and not formed in situ as a result of natural processes common to the estuary. (author)

Sampling practices and analytical techniques used in the monitoring of steam and water in CEGB nuclear boilers

International Nuclear Information System (INIS)

Goodfellow, G.I.

1978-01-01

The steam and water in CEGB Magnox and AGR nuclear boilers are continuously monitored, using both laboratory techniques and on-line instrumentation, in order to maintain the chemical quality within pre-determined limits. The sampling systems in use and some of the difficulties associated with sampling requirements are discussed. The relative merits of chemical instruments installed either locally in various parts of the plant or in centralized instrument rooms are reviewed. The quality of water in nuclear boilers, as with all high-pressure steam-raising plant, is extremely high; consequently very sensitive analytical procedures are required, particularly for monitoring the feed-water of 'once-through boiler' systems. Considerable progress has been made in this field and examples are given of some of the techniques developed for analyses at the 'μ/kg' level together with some of the current problems.(author)

Operational experience in the United Kingdom

International Nuclear Information System (INIS)

Gronow, W.S.

1977-01-01

In the UK there are 26 Magnox reactors and 4 AGRs operating on 11 licensed sites; a further 6 AGRs are under construction on 2 additional and one of the existing sites. The arrangements by which the Nuclear Installations Inspectorate, on behalf of the Health and Safety Executive, carries out its regulatory functions at operating nuclear power plants are described. The range of activities undertaken is described with special reference being made to the biennial shutdowns for approved maintenance and inspections which are required by conditions attached to the site licence. The other means by which the continuing safety of these power reactors is assured are explained and include the relationship with the licensee's own Nuclear Safety Committee, approved arrangements for modifications to plant systems or components which have importance for safety and long term reviews of safety aspects. (author)

Recent UK Experience of Involving the Public in Decisions on Radioactive Discharges

Energy Technology Data Exchange (ETDEWEB)

Smith, R.E. [Environment Agency, London (United Kingdom); Weedon, C.J. [Environment Agency, Penrith (United Kingdom); McGoff, A.; Bower, M. [Environment Agency, Bedford (United Kingdom)

2001-07-01

In January 1998 BNFL applied to the Agency for authorisations to dispose of gaseous, liquid, combustible and solid radioactive wastes in respect of each of Magnox Electric's power stations. The Agency is currently considering BNFL's applications. This is the first time that authorisations for radioactive waste disposal have been considered for all these stations together as a package. It has been a major task for BNFL to assemble all the relevant information and for the Agency to drive the process forward through public consultation to the decision-making stage. As part of its role of protecting and improving the environment, the Agency is committed to progressive reductions in radioactive discharges where practicable, seeking to achieve this through the limits and conditions of any authorisation it issues. It aims to review nuclear site authorisations on a four-yearly cycle and has used BNFL's applications as the basis for its review of the Magnox power station sites. The Agency carefully scrutinised the applications and obtained additional detailed information and clarification from BNFL in response to six rounds of questions. The applications and responses from the company to Agency questions were made publicly available. They include information on: the benefits and detriments of continued operation/decommissioning (as appropriate); the sources and amounts of radioactive waste associated with continued operation/decommissioning; the current levels of discharge of radioactive waste to the environment; and the application of best practicable means (BPM) to minimise discharges. The Agency is considering all the application information and must decide, separately for each power station, whether an authorisation should be issued to BNFL. It has consulted publicly to assist its decision making, the objective being to enable people and organisations to draw to the Agency's attention any matters they would wish it to consider when reaching its

Single phase and two phase erosion corrosion in broilers of gas-cooled reactors

International Nuclear Information System (INIS)

Harrison, G.S.; Fountain, M.J.

1988-01-01

Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 μg/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss

An example of the practical application of ALARP in planning, implementation and review at BNFL's Bradwell Power Station

International Nuclear Information System (INIS)

Devine, I.R.; James, C.

2000-01-01

The paper will describe three examples of the practical application of ALARP principles as applied to some major projects associated with enhancement of the safety cases for heat exchanger or reactor core support structures at some Magnox Power Stations operated by BNFL Magnox Generation. It will summarise and discuss some of the issues encountered during the pre-planning, engineering development/implementation, work in progress and post completion review phases. The first example is the response to minor defects discovered during an inspection of a sample of some welds in an upper restraint beam inside the concrete reactor pressure vessel at Oldbury Power Station. These inspections were carried out to enhance the existing safety case to justify a proposed increase in the period between statutory inspections from two to three years. The presence or absence of similar defects in the other welds was not sufficiently well characterised nor could be sufficiently accurately predicted without extensive additional NDT inspection. This would in itself have incurred a significant dose commitment. The engineering/ALARP assessment was required address the justification of the work and even determine what should be proposed. Available options included: extensive inspection to determine the status of load bearing welds to enable a subsequent assessment of the required remedial work (if any) which may include weld dressing, repair or reinforcement; pre-emptive reinforcement on a 'worst case scenario', or pre-emptive complete or partial weld repair. The second and third case studies relate to the response to minor defects in welds associated with support beams inside heat exchangers at Bradwell and Hinkley Point Power Stations. In these cases, pre-emptive repair or reinforcement was clearly justified and optimal. The engineering/ALARP assessments were required to address the optimisation of the required repair or reinforcement strategy and tasks associated with its implementation

Single phase and two phase erosion corrosion in broilers of gas-cooled reactors

Energy Technology Data Exchange (ETDEWEB)

Harrison, G S; Fountain, M J [Operational Engineering Division (Northern Area), Central Electricity Generating Board, Manchester (United Kingdom)

1988-07-01

Erosion-corrosion is a phenomenon causing metal wastage in a variety of locations in water and water-steam circuits throughout the power generation industry. Erosion-corrosion can occur in a number of regions of the once-through boiler designs used in the later Magnox and AGR type of gas cooled nuclear reactor. This paper will consider two cases of erosion-corrosion damage (single and two phase) in once through boilers of gas cooled reactors and will describe the solutions that have been developed. The single phase problem is associated with erosion-corrosion damage of mild steel downstream of a boiler inlet flow control orifice. With metal loss rates of up to 1 mm/year at 150 deg. C and pH in the range 9.0-9.4 it was found that 5 {mu}g/kg oxygen was sufficient to reduce erosion-corrosion rates to less than 0.02 mm/year. A combined oxygen-ammonia-hydrazine feedwater regime was developed and validated to eliminate oxygen carryover and hence give protection from stress corrosion in the austenitic section of the AGR once through boiler whilst still providing erosion-corrosion control. Two phase erosion-corrosion tube failures have occurred in the evaporator of the mild steel once through boilers of the later Magnox reactors operating at pressures in the range 35-40 bar. Rig studies have shown that amines dosed in the feedwater can provide a significant reduction in metal loss rates and a tube lifetime assessment technique has been developed to predict potential tube failure profiles in a fully operational boiler. The solutions identified for both problems have been successfully implemented and the experience obtained following implementation including any problems or other benefits arising from the introduction of the new regimes will be presented. Methods for monitoring and evaluating the efficiency of the solutions have been developed and the results from these exercises will also be discussed. Consideration will also be given to the similarities in the metal loss

The application of research and technology in the Highly Active Liquor storage and treatment facilities at Sellafield

International Nuclear Information System (INIS)

Nixon, C.R.

2004-01-01

At the Sellafield nuclear site, Highly Active Liquor (HAL) produced from Magnox and Oxide reprocessing operations is evaporated and interim stored in the Highly Active Liquor Evaporation and Storage (HALES) complex prior to vitrification in one of three Waste Vitrification Plant (WVP) processing lines. These plants are integral to the current commercial activities at Sellafield and also in safely discharging liabilities in the future. The management and operation of HALES and WVP are subject to significant regulatory and public scrutiny and there is the requirement to deliver a reduction in the HAL volumes stored in HALES in accordance with a regulator imposed HAL stock reduction specification. In delivering the required reduction BNFL has faced a number of technical and operational challenges which have resulted in the development and execution of significant programmes of research and development and technical and engineering projects. The key challenges faced are briefly presented. (author)

Magnesium and related low alloys

International Nuclear Information System (INIS)

Bernard, J.; Caillat, R.; Darras, R.

1959-01-01

In the first part the authors examine the comparative corrosion of commercial magnesium, of a magnesium-zirconium alloy (0,4 per cent ≤ Zr ≤ 0,7 per cent) of a ternary magnesium-zinc-zirconium alloy (0,8 per cent ≤ Zn ≤ 1,2 per cent) and of english 'Magnox type' alloys, in dry carbon dioxide-free air, in damp carbon dioxide-free air, and in dry and damp carbon dioxide, at temperatures from 300 to 600 deg. C. In the second part the structural stability of these materials is studied after annealings, of 10 to 1000 hours at 300 to 450 deg. C. Variations in grain after these heat treatments and mechanical stretching properties at room temperature are presented. Finally various creep rate and life time diagrams are given for these materials, for temperatures ranging from 300 to 450 deg. C. (author) [fr

The economic failure of nuclear power in Britain

International Nuclear Information System (INIS)

Henney, A.

1990-01-01

Claims made about the economics of nuclear power have been misleading. The history and political framework within which nuclear power has developed in Britain are explained so that those claims can be understood. The main factors affecting the development of nuclear power in Britain have been military requirements, national pride, the hope of cheap electricity and concern about the security of fuel supplies. Variations in the official view of the economics of Magnox reactors are used to illustrate changes in the government attitude to nuclear power economics. Other factors - the 'oil crisis' of the 1970's the miners' strike, the accident at Three Mile Island and methods of accounting are all shown to influence this attitude. At the Hinkley Point C Inquiry the Central Electricity Generating Board conceded that nuclear power was not economic a position recognised by the government in the non-privatisation of nuclear power. (UK)

Nuclear power now and in the future

Energy Technology Data Exchange (ETDEWEB)

Collier, J G [Nuclear Electric (United Kingdom)

1991-08-01

The future of the nuclear industry in the United Kingdom is considered from the perspective of the new public sector utility, Nuclear Electric, set up to retain control of nuclear power stations on the privatization of the rest of the electricity supply industry. Two major objectives are the increased nuclear generation of electricity and the cutting of costs. These are discussed in terms of life extension programmes for the magnox reactors, improved performance of AGR reactors and expectations for the Sizewell B PWR station now under construction; waste management, reactor decommissioning and fuel-cycle costs are also considered. Economic, environmental and political criteria are outlined which need to be addressed in relation to the government's review of nuclear power in 1991. Because of the marginal economic advantages of nuclear power in the United Kingdom, it will be important to quantify the environmental and diversity benefits of this source. (UK).

Improvements to the transient solution in the PANTHER space-time code

International Nuclear Information System (INIS)

Kutt, P.K.; Knight, M.P.

1993-01-01

The three dimensional, two-group, nodal diffusion code PANTHER has been developed for the analysis of almost all thermal reactor types [pressurized water reactor (PWR), boiling water reactor, VVER, RBMK, advanced gas-cooled reactor, MAGNOX]. It can perform a comprehensive range of calculations for fuel management, operational support including on-line application, and transient analysis. Transient results for a number of light water reactor (LWR) benchmark problems have been reported previously. This paper outlines some recent developments of the transient solution in PANTHER, showing results for two LWR benchmark problems. Recently, PANTHER results have been accepted as the reference solutions for a Nuclear Energy Agency Committee on Reactor Physics (NEACRP) rod ejection benchmark Unlike previous simplified rod ejection benchmarks, it represents a real PWR with a detailed thermal model and cross sections dependent on boron, fuel temperature, and water density and temperature. This reference solution was computed with fine time steps

The nuclear fuel cycle: (2) fuel element manufacture

International Nuclear Information System (INIS)

Doran, J.

1976-01-01

Large-scale production of nuclear fuel in the United Kingdom is carried out at Springfields Works of British Nuclear Fuels Ltd., a company formed from the United Kingdom Atomic Energy Authority in 1971. The paper describes in some detail the Springfields Works processes for the conversion of uranium ore concentrate to uranium tetrafluoride, then conversion of the tetrafluoride to either uranium metal for cladding in Magnox to form fuel for the British Mk I gas-cooled reactors, or to uranium hexafluoride for enrichment of the fissile 235 U isotope content at the Capenhurst Works of BNFL. Details are given of the reconversion at Springfields Works of this enriched uranium hexafluoride to uranium dioxide, which is pelleted and then clad in either stainless steel or zircaloy containers to form the fuel assemblies for the British Mk II AGR or advanced gas-cooled reactors or for the water reactor fuels. (author)

[Trawsfynydd] station aims to be third time lucky [with re-opening

International Nuclear Information System (INIS)

Patel, K.

1992-01-01

The Trawsfynydd Magnox power station in the United Kingdom was shut down last year after it was discovered that welds in the reactor's steel pressure vessel were becoming brittle. The Nuclear Installation Inspectorate (NII) says that the reasons for shutting down Trawsfynydd and refusing to allow the power generator to reopen the facility centre rest on two key issues. Firstly, says the NII, there are uncertainties regarding the changes in vessel material properties because of neutron irradiation that came to light in late 1990. The inspectorate also says that there is concern over the extended operation of parts of the vessel below the temperature at which the steel within it can be confidently predicted to exhibit ductile properties. The generator, Nuclear Electric, is optimistic that it will be able to allay these fears at its third attempt in September. The problems are examined in this article. (Author)

Polymer and bitumen-modified OPC for the immobilization of ILW

International Nuclear Information System (INIS)

Johnson, D.I.; Worrall, G.; Phillips, D.C.

1986-01-01

A detailed study has been made of the modification of ordinary Portland cement with polymeric additives, and of the properties of waste forms based on these matrix materials. The additives were styrene butadiene and bitumen emulsions, and epoxide and polyurethane resins: the simulated wastes were organic ion exchanger beads, PWR evaporator concentrate, reprocessing concentrate and Magnox metal. The effect of polymer: cement (p:c) and water:cement ratios on the properties of the hardened cement paste has been comprehensively investigated. Substantial increases in strain to failure, and modest reductions in permeability to water and leach rates for Cs 137 , are obtained at p:c > 0.2. Much larger volume fractions of organic ion exchange beads can be encapsulated in polymer modified OPC than in unmodified OPC, perhaps because of their better strain capability. The radiation stability of cemented PWR evaporator concentrate is better for a polymer-modified matrix than an unmodified OPC matrix. Two hundred litre trials have been successfully demonstrated. 20 refs, 20 tabs, 10 figs

Polymer and bitumen modified OPC for the immobilisation of ILW

International Nuclear Information System (INIS)

Johnson, D.I.; Worrall, G.; Phillips, D.C.

1986-05-01

A detailed study has been made of the modification of ordinary Portland cement with polymeric additives, and of the properties of waste forms based on these matrix materials. The additives were styrene butadiene and bitumen emulsions, and epoxide and polyurethane resins: the simulated wastes were organic ion exchanger beads, PWR evaporator concentrate, reprocessing concentrate and Magnox metal. The effect of polymer:cement (p:c) and water:cement ratios on the properties of the hardened cement paste has been comprehensively investigated. Substantial increases in strain to failure, and modest reductions in permeability to water and leach rates for 137 Cs, are obtained at p:c >= 0.2. Much larger volume fractions of organic ion exchange beads can be encapsulated in polymer modified OPC than in unmodified OPC, perhaps because of their better strain capability. The radiation stability of cemented PWR evaporator concentrate is better for a polymer modified matrix than an unmodified OPC matrix. Two hundred litre trials have been successfully demonstrated. (author)

Reviewing nuclear power station achievement

International Nuclear Information System (INIS)

Howles, L.R.

1976-01-01

For measurement of nuclear power station achievement against original purchase the usual gross output figures are of little value since the term loosely covers many different definitions. An authentically designed output figure has been established which relates to net design output plus house load at full load. Based on these figures both cumulative and moving annual load factors are measured, the latter measuring the achievement over the last year, thus showing trends with time. Calculations have been carried out for all nuclear stations in the Western World with 150 MW(e) gross design output and above. From these are shown: moving annual load factor indicating relative station achievements for all the plants; cumulative load factors from which return of investment can be calculated; average moving annual load factors for the four types of system Magnox, PWR, HWR, and BWR; and a relative comparison of achievement by country in a few cases. (U.K.)

Ten year report on the operation of the Latina nuclear power station 1964-1973

International Nuclear Information System (INIS)

1976-07-01

The final report on the operation of the Latina nuclear power station, required under the terms of the contract of participation between ENEL and EURATOM is presented. It covers the first ten years of commercial operation (1 January 1964-31 December 1973) of this power station. Latina uses a British Magnox-type gas-graphite natural uranium reactor with a design thermal capacity of 724 MW. The rated electrical output of the three main turbogenerators was originally 210 MW (3x70), but was reduced to 160 MW in 1971. Construction began in November 1958 and was completed when the reactor first reached criticality in December 1962, the station being connected to the Italian electricity network for the first time in May 1963. The gross rated output of 210 MWe was reached in December 1963 and commercial operation began on 1 January 1964, by which date, however, the power station had already fed 295.5 million kWh into the network

The nuclear review

International Nuclear Information System (INIS)

Robinson, C.

1995-01-01

Evidence in favour of privatisation which was submitted to the UK government's review of the nuclear industry is summarised. Only if capital markets judge proposals for new nuclear stations and they operate within competitive markets, can their economic and commercial viability be determined. The problem of state ownership is that politicians' time horizons are too short for an industry that must take a long view, unless standards are set by competitors, costs are likely to rise. Magnox stations, however, should remain in public ownership though to gain efficiency their operation should be contracted out. The rest of Nuclear Electric and Scottish Nuclear should be privatised as generation companies but should not be tied to nuclear generation. Current protective arrangements should be removed as soon as possible. Among the benefits expected from the entry of two formidable new companies into the privatised electricity are efficiency gains, price reductions, a stimulus to entrepeneurship and innovation, and more straightforward regulation. (UK)

A new model validation database for evaluating AERMOD, NRPB R91 and ADMS using krypton-85 data from BNFL Sellafield

International Nuclear Information System (INIS)

Hill, R.; Taylor, J.; Lowles, I.; Emmerson, K.; Parker, T.

2004-01-01

The emission of krypton-85 ( 85 Kr) from nuclear fuel reprocessing operations provide a classical passive tracer for the study of atmospheric dispersion. This is because of the persistence of this radioisotope in the atmosphere, due to its long radioactive halflife and inert chemistry; and the low background levels that result due to the limited number of anthropogenic sources globally. The BNFL Sellafield site in Cumbria (UK) is one of the most significant point sources of 85 Kr in the northern hemisphere, with 85 Kr being discharged from two stacks on the site, MAGNOX and THORP. Field experiments have been conducted since October 1996 using a cryogenic distillation technique (Janssens et al., 1986) to quantify the ground level concentration of 85 Kr. This paper reports on the construction of a model validation database to allow evaluation of regulatory atmospheric dispersion models using the measured 85 Kr concentrations as a tracer. The results of the database for local and regional scale dispersion are presented. (orig.)

Thermo-hydraulic characteristics of serpentine tubing in the boilers of gas cooled reactors under condition of rapid and slow depressurization

International Nuclear Information System (INIS)

Abouhadra, D.S.; Byrne, J.E.

2003-01-01

In nuclear reactors of the magnox or advanced gas cooled type, serpentine tubing is used in some designs to generate steam in a once through arrangement. The calculation of accidents using two phase flow codes requires knowledge of the heat transfer behaviour of the boiler steam side. A series of experiments to study the blowdown characteristics of a typical serpentine boiler section was devised in order to validate the MARTHA section of the MACE code used by nuclear electric . The tests were carried out on the thermal hydraulics experimental research assembly (THERA) loop at manchester university. Depressurization from an initial pressure of 60 bar, with fluid subcooling of 5 k, 50 k, and 100 k was controlled by discharging the test section contents through suitably chosen orifices to produce blowdown to 10% of the initial pressure over a time scale of 30 s to 3600 s. pressures and temperatures in the serpentine were measured at average time intervals of approximately 1 s

On the economic prospects of nuclear fusion with tokamaks

International Nuclear Information System (INIS)

Pfirsch, D.; Schmitter, K.H.

1987-12-01

This paper describes a method of cost and construction energy estimation for tokamak fusion power stations conforming to the present, early stage of fusion development. The method is based on first-wall heat load constraints rather than β limitations, which, however, might eventually be the more critical of the two. It is used to discuss the economic efficiency of pure fusion, with particular reference to the European study entitled 'Environmental Impact and Economic Prospects of Nuclear Fusion'. It is shown that the claims made therein for the economic prospects of pure fusion with tokamaks, when discussed on the basis of the present-day technology, do not stand up to critical examination. A fusion-fission hybrid, however, could afford more positive prospects. Support for the stated method is even derived when it is properly applied for cost estimation of advanced gascooled and Magnox reactors, the two very examples presented by the European study to 'disprove' it. (orig.)

Gas reactor and associated nuclear experience in the UK relevant to high temperature reactor engineering

International Nuclear Information System (INIS)

Beech, D.J.; May, R.

2000-01-01

In the UK, the NNC played a leading role in the design and build of all of the UK's commercial magnox reactors and advanced gas-cooled reactors (AGRs). It was also involved in the DRAGON project and was responsible for producing designs for large scale HTRs and other gas reactor designs employing helium and carbon dioxide coolants. This paper addresses the gas reactor experience and its relevance to the current HTR designs under development which use helium as the coolant, through the consideration of a representative sample of the issues addressed in the UK by the NNC in support of the AGR and other reactor programmes. Modern HTR designs provide unique engineering challenges. The success of the AGR design, reflected in the extended lifetimes agreed upon by the licensing authorities at many stations, indicates that these challenges can be successfully overcome. The UK experience is unique and provides substantial support to future gas reactor and high temperature engineering studies. (authors)

The Davros III supervisory control system

International Nuclear Information System (INIS)

Rice, P.

1996-01-01

Magnox Electric's Remote Operations Branch deploy a wide variety of remote inspection and maintenance tools into nuclear plant in order to perform a variety of tasks. In recent years much progress has been made on low-level control of individual manipulator axes, and a parallel need has emerged for a supervisory system to assist the operator in the control of the whole system. Some requirements are: 1) to improve operator control of systems; 2) to simplify software maintenance and version control; 3) to reduce the likelihood of damage to manipulators; 4) to assist with rehearsals and simulations. Davros III is a PC software system which has been developed over a number of years to address these requirements. In a single program capable of being configured for a wide variety of applications, it provides a technique for following pretaught routes, a comprehensive and fully configurable interlock system and several different facilities for simulation. (author)

The Davros III supervisory control system

International Nuclear Information System (INIS)

Rice, P.

1996-01-01

Magnox Electric's Remote Operations Bbranch deploy a wide variety of remote inspection and maintenance tools into nuclear plant in order to perform a variety of tasks. In recent years much progress has been made on low-level control of individual manipulator axes and a parallel need has emerged for a supervisory system to assist the operator in the control of the whole system. Some requirements are: 1, To improve operator control of systems. 2, To simplify software maintenance and version control. 3, To reduce the likelihood of damage to manipulators. 4, To assist with rehearsals and simulations. Davros III is a PC software system which has been developed over a number of years to address these requirements. In a single program capable of being configured for a wide variety of applications, it provides a technique for following pretaught routes, a comprehensive and fully configurable interlock system and several different facilities for simulation. (author)

Experience of ALARA in controlling radiocaesium discharges to the Irish Sea

International Nuclear Information System (INIS)

Hunt, G.J.

1984-01-01

Radiocaesium discharges to the Irish Sea, which primarily originate from corrosion of magnox fuel in the Sellafield storage ponds, are a source of public radiation exposure mainly through the fish and shellfish consumption pathway. Experience of ALARA in the context of reducing these discharges is described. The operators, British Nuclear Fuels Limited (BNFL), in consultation with Government Departments, decided to install an ion exchange plant to remove radioactivity from pond effluents. This plant is scheduled for commissioning in 1984 and optimisation will play a major part in determining its operating regime. Meanwhile, measures have been taken to reduce discharges using skips of zeolite installed in the ponds. Experience of ALARA in determining the optimum replacement rate of skips is described. A major consideration was differential cost-benefit analysis. Following installation of skips at the rate thereby indicated, discharges are being reduced by about half. A further major reduction is expected when the ion exchange plant becomes available. (author)

Juggling the figures

International Nuclear Information System (INIS)

Webster, David.

1987-01-01

There are three options as to how to cope with a nuclear reactor when it reaches the end of its operating life - simply withdraw the fuel rods and leave the structure standing, entombment or dismantling. The UKAEA have chosen to dismantle the WAGR reactor. This decision is criticised on the grounds that it will create large quantities of radioactive dust and liquids and disperse the radioactivity throughout the environment. The removal of the low and intermediate-level wastes will be expensive - it will be packaged in reinforced concrete boxes and as yet no disposal site has been found for intermediate-level wastes. Greenpeace support leaving disused reactors alone until a better option is available for waste disposal. Dismantling an AGR will not, it is argued, give the UKAEA the dismantling experience it needs as it will be the Magnox reactors that will end their service life first, and the techniques needed will be different. The UKAEA is accused of 'playing with robots'. (UK)

Public concern for decommissioning - why it must be addressed

International Nuclear Information System (INIS)

Kay, Martin.

1997-01-01

To demonstrate its responsible approach, the nuclear industry in the United Kingdom must recognise the benefits of satisfying and gaining the consent of the stakeholder society in the pursuit of its legitimate goals. Public acceptance can be achieved only by establishing and maintaining trust through two-way communication. Stakeholder audiences still perceive that waste management and decommissioning are the industry's ''achilles heel''. The simple message to be delivered is that waste and decommissioning are being managed safely, sensibly and ecnomically. An exemplar of how public consent may be gained is the consultation carried out by Magnox Electric with local stakeholders on the decommissioning strategy for the Trawsfyndd nuclear power plant. The basic strategy was confirmed but details were changed to take account of local concerns. Some valuable lessons learned were: communications should be integrated into the planning process as a strategic issue; openess is a cornerstone of good communication; gaining public trust and respect is fundamental; key stake holders need to be identified carefully. (UK)

Studies, Transport and Treatment Concept for Boilers from Berkeley NPP, England - 13599

International Nuclear Information System (INIS)

Wirendal, Bo; Saul, David; Robinson, Joe; Davidson, Gavin

2013-01-01

In November 2011 Studsvik was awarded a contract to transport five decommissioned boilers from the Berkeley Nuclear Licensed Site in the UK to the Studsvik Nuclear Site in Sweden for metal treatment and recycling. A key objective of the project was to remove the boilers from the site by 31 March 2012 and this was successfully achieved with all boilers off site by 22 March and delivered to Studsvik on 6 April. Four boilers have been processed and the fifth is planned for completion by end of December 2012.The project had many challenges including a very tight timescale and has been successfully delivered to cost and ahead of the baseline programme. This paper describes the project and the experience gained from treatment of the first four boilers. It is the first UK project to send large components overseas for recycling and provides new insight into the processing of Magnox gas-circuit components. (authors)

Removal of concrete layers from biological shields by microwaves

International Nuclear Information System (INIS)

Wace, P.F.; Harker, A.H.; Hills, D.L.

1990-01-01

A comprehensive literature review has been carried out, to provide information for an experimental programme and equipment design. Mathematical modelling of the microwave and power fields in a concrete block, both steel reinforced and unreinforced, subjected to a microwave attack at two frequencies, has been carried out and estimates of the likely temperature rise with time obtained. A method of launching microwaves into concrete has been established from theoretical considerations and from the findings of the literature review. Equipment for laboratory trials has been designed and assembled using an 896 MHz, 25 kW microwave generator. Reinforced concrete blocks, 0.6 m in dimension and representing the concrete in a Magnox reactor biological shield, have been attacked at different power levels and the surface removed to the depth of the reinforcing steel (100 mm). Outline proposals for the design of a remotely operated prototype microwave machine for stripping the surface of large concrete test panels have been prepared. (author)

Nuclear technology international 1987

International Nuclear Information System (INIS)

Geary, Neville

1987-01-01

A total of 59 articles cover a wide range of subjects within the scope of nuclear power generation. The first 13 are concerned with the design and construction of nuclear reactors - PWRs, AGRs, Magnox reactors, fast reactors. The final article in this section is on reactor decommissioning. The next 33 papers all concern services to the nuclear power industry. These include the supply of uranium, uranium enrichment, fuel fabrication, reprocessing, spent fuel storage, robotics and remote handling and radioactive waste disposal. The 13 articles in the safety and public acceptability section concern fears over the Chernobyl accident, safety aspects of nuclear power including risk assessment, fire protection, quality assurance, earthquake tolerance, non-proliferation of nuclear weapons and finally, general problems of balancing advances in nuclear technology and economic desirability against a lack of public confidence in the industry. All reactor and fuel types are represented. Most of the articles concern nuclear power in Europe or North America. All are indexed separately. (UK)

Bradwell Nuclear Power Station

International Nuclear Information System (INIS)

1987-01-01

When built, the Magnox reactors were expected to have operating lifetimes of 20-25 years. In order to satisfy the licensing authorities of their continued safety, long term safety reviews (LTSRs) are being carried out as the reactors reach 20 years of operation. This is the Nuclear Installations Inspectorate's (NII) summary report on Bradwell nuclear power station. The objectives of the LTSR are stated. A description of the plant is followed by an explanation of the statutory position on licensing. The responsibilities of the Central Electricity Generating Board (CEGB) and the NII are defined. From the examination of the CEGB's LTSR it is concluded that this generally confirms the validity of the existing safety case for present operation. However, some recommendations are made as to work required for reactor operation up to 1992. A summary of the NII findings is presented. This includes the reactor pressure circuit integrity, effects of ageing and in-service wear and radiation doses. (U.K.)

UK nuclear power: gone but not forgotten

International Nuclear Information System (INIS)

Anon.

1990-01-01

The nuclear power industry in Britain will not now be privatised. The future of nuclear power in the UK is discussed. In Scotland the South of Scotland Electricity Board will be expecting to sell some of its electricity to Britain. The structure of the new electricity supply industry in Scotland will also be unusual with most of the country's electricity being produced by a state-run company, while two private companies produce the rest and sell it on to customers. The situation in England is uncertain mainly because of the policy and potential costs involved in decommissioning of the Magnox stations as they are shutdown at the end of their service life. The privatisation of the electricity industry has highlighted the problems of decommissioning. It has also shown that the nuclear industry assumed itself to be immortal and has also assumed that money is not important, an attitude which has alarmed the City financiers. (UK)

Status of national gas cooled reactor programmes

International Nuclear Information System (INIS)

1991-08-01

This report has been compiled as a central source of summary-level information on the present status of High Temperature Gas-Cooled Reactor (HTGR) programmes in the world and on future plans for the continued development and deployment of HTGRs. Most of the information concerns the programmes in the United States, Germany, Japan and the Soviet Union, countries that have had large programmes related to HTGR technology for several years. Summary-level information is also provided in the report on HTGR-related activities in several other countries who either have an increasing interest in the technology and/or who are performing some development efforts related to HTGR technology. The report contains a summary-level update on the MAGNOX and AGR programmes. This is the twelfth issue of the document, the first of which was issued in March, 1979. The report has been prepared in the IAEA Nuclear Power Technology Development Section. Figs and tabs

The Safety Assessment of Long term Interim Storage at Sellafield

International Nuclear Information System (INIS)

Buchan, Andrew B.

2014-01-01

The Sellafield site comprises a wide range of nuclear facilities, including operating facilities associated with the Magnox reprocessing programme, the Thermal Oxide Reprocessing Plant (THORP) and a range of waste treatment plants. The operational life of some of the site facilities currently extends to 2120, requiring the retrieval, treatment, consolidation and safe extended storage of a variety of radioactive materials. Sellafield has utilised its existing safety assessment processes to inform and prioritise studies into beyond design basis events and resilience evaluation required following Fukushima by UK regulators and industry bodies such as WANO. There are significant differences between NPPs, for which the ENSREG 'stress tests' were originally intended, and the Sellafield site which is instead centered around two reprocessing facilities (Magnox and THORP), with a supporting infrastructure of waste processing and storage facilities, coupled with a legacy of high hazard older facilities. In the former case the consequences of a catastrophic failure are promptly realised, leading to significant problems such as fuel failure / meltdown in AGRs and LWRs respectively in the event of complete loss of cooling. At Sellafield, the processes are carried out at comparatively low temperatures and pressures with relatively low rates of change following any loss of cooling. Instead the consequences of catastrophic failure at Sellafield are more directly related to the very large inventories of radioactive materials, including high level liquid wastes and unprocessed fuels, present in specific plants and to the condition of the ageing assets, holding legacy wastes. The paper will consider how a number of analysis techniques have been used to establish a safety case for fault and accident conditions, i.e. design basis analysis (DBA), probabilistic safety analysis (PSA) and severe accident analysis (SAA) DBA is focused on the key safety measures for those initiating faults

Challenge of Replacing Obsolete Equipment and Systems on Brownfield Sites

International Nuclear Information System (INIS)

Teasdale, St.

2009-01-01

The Nuclear Decommissioning Authority (NDA) is responsible for the decommissioning and clean-up of the UK's civil public sector nuclear sites. One of their top priorities is the retrieval of sludge and fuel from the First Generation Magnox Fuel Storage Pond (FGMSP) at Sellafield site which is one of the most complex and compact nuclear sites in the world. The FGMSP plant is currently undergoing a series of major modifications in preparation for the retrievals operations. One of the most challenging modifications undertaken in the facility has been the Control and Surveillance Project which covered replacement of the existing Environmental Monitoring System, this presented the complex challenge of replacing an existing system whilst maintaining full functionality on a live radiological safety system with a constant radiological hazard. The Control and Surveillance Project involved the design, procurement, installation, changeover and commissioning of a new Radiological Surveillance System (alpha, beta and gamma monitoring) along with Building Evacuation Systems within the FGMSP complex to replace the existing obsolete system. This Project was a key enabler to future FGMSP retrievals and decommissioning activities. The project objective was to create and maintain a safe radiological working environment for over 450 personnel working in the plant up to 2020. The Legacy Ponds at Sellafield represent one of the biggest challenges in the civil nuclear clean up portfolio in the UK. Retrieval of sludge and fuel from the First Generation Magnox Fuel Storage Pond (FGMSP), and its safe long term storage is one of the NDA's top priorities. In June 2002 Sellafield Ltd contracted with the ACKtiv Nuclear Joint Venture to progress the risk mitigation, asset restoration and the early enabling works associated with preparation for clean up. Since then significant progress has been made in preparing the facility, and it's support systems, for the clean-up operations. This has been

Sorption on inactive repository components

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1990-11-01

The near-field of an intermediate level/low level radioactive waste repository will contain significant quantities of iron and steel, Magnox and Zircaloy. Their corrosion products may possess significant sorption capacity for radioelements. The sorption of americium and plutonium onto magnesium hydroxide, zirconium hydroxide, colloidal magnetite and colloidal haematite has been studied under conditions typical of the porewater of a cementitious near-field. R D values ≥ 10 5 m g -1 were measured for both actinides on the oxides and hydroxides. These values are at least as great as those measured on crushed 3:1 Blast Furnace Slag/Ordinary Portland cement. Competitive sorption experiments have shown that sorption onto the corrosion products does not take place in preference to that on the cement or the converse. Magnetite and haematite colloids are positively charged in cement-equilibrated water whilst zirconium hydroxide is negatively charged. Crushed cement was found to be positively charged. Simple experiments show that only a small proportion of haematite colloids is potentially mobile through a column of crushed cement. (author)

Sorption on inactive repository components

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1990-07-01

The near-field of an intermediate level/low level radioactive waste repository will contain significant quantities of iron and steel, Magnox and Zircaloy. Their corrosion products may possess significant sorption capacity for radioelements. The sorption of americium and plutonium onto magnesium hydroxide, zirconium hydroxide, colloidal magnetite and colloidal haematite has been studied under conditions typical of the porewater of a cementitious near-field. R D values ≥ 10 5 ml g -1 were measured for both actinides on the oxides and hydroxides. These values are at least as great at those measured on crushed 3:1 Blast Furnace Slag/Ordinary Portland Cement. Competitive sorption experiments have shown that sorption onto the corrosion products does not take place in preference to that on the cement or the converse. Magnetite and haematite colloids are positively charged in cement-equilibrated water whilst zirconium hydroxide is negatively charged. Crushed cement was found to be positively charged. Simple experiments show that only a small proportion of haematite colloids is potentially mobile through a column of crushed cement. (author)

The mathematical modelling of plant behaviour: an evolutionary history and forward projection: Pt. 3

International Nuclear Information System (INIS)

Whitmarsh-Everiss, M.J.

1993-01-01

The two previous articles in this series considered the evolution of analogue and hybrid computing techniques using examples from Magnox and advanced gas cooled reactor design. The parallel deployment and development of digital computing was discussed in relation to the simulation languages of the day which culminated in the formal release of the Plant Modelling Systems Program, PMSP. It is now proposed to trace the history from 1980 to the present day and discuss the highly sophisticated interactive digital computing environment known as the Plant Design Analyser. A backward step will be taken in time to look at the parallel and evolving design of Plant Operator Training Simulators. Once again, the development of these facilities had to track the evolving computer architectures and developments in computing science. During this period modelling disciplines and methodologies became formalised and were enshrined in elaborate Computer Aided Design Suites. However, they were consolidated at the end of our story. It is first our intention to discuss the simulation language PMSP as this is the foundation of the explanation which follows. (author)

National report on nuclear power plant control and instrumentation in the United Kingdom

International Nuclear Information System (INIS)

Goodings, A.

1992-01-01

This paper notes that, although no fundamental, NPPC and I technical developments have taken place in the UK since 1989, enormous organizational changes have occurred. The influence of these changes on instrumentation capability is discussed and the current situations on the Magnox, AGR and Fast Reactors and on the Sizewell PWR are described. Work on pulse-coded-logic reactor trip systems based on conventional microprocessor components is noted and a new, Dungeness B AGR, single channel trip systems which uses these principles is described. Other developments in sensors, instrumentation, ultrasonics and under-sodium viewing are also described as are studies on software reliability, human factors engineering and related topics. Comments are made on general aspects of computers in reactor safety systems. It is concluded that the last two years have seen considerable progress in the UK despite the interruptions and problems generated by organizational changes. It is felt that these changes may have produced a new sense of urgency and better insights into the needs of the industry. (author). 2 refs

Application of model based predictive control to a solvent extraction plant

International Nuclear Information System (INIS)

Harper, W.J.

1995-01-01

British Nuclear Fuels plc. (BNFL) is the most experienced nuclear fuel company in the world, having supplied nuclear fuel cycle services in the UK and overseas for over forty years. BNFL is one of only two companies in the world that is able to offer nuclear fuel manufacture, enrichment, reprocessing and waste management services. In addition to its work for the UK Nuclear Power Programme, BNFL has developed a substantial export business with nuclear power plant operators in Western Europe, Japan and North America, which now accounts for 18% of the annual turnover. BNFL's plants re situated in North West England and Southern Scotland. Nuclear fuel and fuel products are manufactured at Springfields near Preston; uranium enrichment by the centrifuge process is carried out at Capenhurst, near Chester; reprocessing and waste management services are provided at Sellafield, West Cumbria. The Company's headquarters and engineering design facilities are based at Risley, near Warrington. BNFL also owns and operates two (MAGNOX) nuclear power stations-Calder Hall, on the Sellafield site, the Chapelcross, near Dumfries in Southern Scotland

A design study for a fission product fixation plant and storage at Windscale

International Nuclear Information System (INIS)

Hill, K.M.; Ridley, G.; Adler, D.G.

1961-01-01

A flowsheet for a production plant has been worked out and the problems of designing a reliable production plant utilising it have been assessed. The properties of current glass compositions have been considered in relation to problems of permanent storage for periods of 800 to 1000 years and various storage proposals assessed. The performance of the preferred type of storage, i.e. dry storage in natural draught air-cooled vaults, has been estimated and consideration given to a number of variables affecting the optimum design. The design problems of a storage of the required life have been investigated in relation to suitable types of site and proposals made as to the types of construction to be used. Design work on tunnel loading facilities has been carried to the state of demonstrating feasibility. The capital costs and the economics of this type of waste storage have been investigated for unalloyed Magnox fuel and brief consideration given to alloyed and cermet fuels. Attention has been given to development problems of the whole system where they arise. (author)

BNFL/Siemens to merge?

International Nuclear Information System (INIS)

Anon.

1997-01-01

Negotiations are being conducted on the creation of a joint venture between British Nuclear Fuels Limited (BNFL) and the German company Siemens. The venture would merge Siemens' nuclear fuel, engineering and construction services businesses with BNFL's Magnox and AGR fuel fabrication business which is based at Springfields in Lancashire. It would incorporate Siemens' share of Nuclear Power International, a joint venture with the French company Framatone which is developing the European Pressurised Water Reactor project, and its US subsidiary Siemens' Power Corp. BNFL's mixed oxide (MOX) fuel fabrication business, its stake in the Dutch-German-UK uranium enrichment company Urenco and its nuclear waste reprocessing business would not be involved. There is already speculation that Siemens' greater input will lead to it taking a majority stake in what will be the world's second largest nuclear fuel manufacturer. Reaction to the news is reported. This has been muted in the United Kingdom, mixed in Germany and adverse in France because of the implications for the Siemens' Framatone collaboration. (UK)

A Study of the Oxidation Behaviour of Pile Grade A (PGA) Nuclear Graphite Using Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and X-Ray Tomography (XRT).

Science.gov (United States)

Payne, Liam; Heard, Peter J; Scott, Thomas B

2015-01-01

Pile grade A (PGA) graphite was used as a material for moderating and reflecting neutrons in the UK's first generation Magnox nuclear power reactors. As all but one of these reactors are now shut down there is a need to understand the residual state of the material prior to decommissioning of the cores, in particular the location and concentration of key radio-contaminants such as 14C. The oxidation behaviour of unirradiated PGA graphite was studied, in the temperature range 600-1050°C, in air and nitrogen using thermogravimetric analysis, scanning electron microscopy and X-ray tomography to investigate the possibility of using thermal degradation techniques to examine 14C distribution within irradiated material. The thermal decomposition of PGA graphite was observed to follow the three oxidation regimes historically identified by previous workers with limited, uniform oxidation at temperatures below 600°C and substantial, external oxidation at higher temperatures. This work demonstrates that the different oxidation regimes of PGA graphite could be developed into a methodology to characterise the distribution and concentration of 14C in irradiated graphite by thermal treatment.

Optimisation of treatment, storage and disposal strategies for (unconditioned and conditioned) radioactive waste

International Nuclear Information System (INIS)

Bealby, J.

1989-03-01

This study examines the trade-offs involved between unconditioned and conditioned waste storage, by investigating the effects of different cost and environmental minimisation strategies on radioactive waste treatment and disposal strategies. The costs and environmental impacts from storage (unconditioned and conditioned), conditioning, transport and disposal are examined. A single generic mixed Magnox/AGR site is investigated, assuming a moderate nuclear power growth scenario over the period 1986 to 2030. Assessments have been performed for four weighting sets which cover the range of views perceived to exist about the relative importance of cost and environmental impact reduction. The base case conditioning option considers the availability of a LLW low force compaction plant in 1986 and two ILW conditioning plants (cement encapsulation and dissolution) in 1990. A base case set of disposal options considers the options of disposal to shallow land and burial facility and deep cavity facilities. The study investigates the effect of deferring the opening dates of the conditioning plants. A set of sensitivity studies show that the assessments are robust to the assumptions and impact parameters used. (author)

Measurement techniques for AGR circulators in a full-density rig

International Nuclear Information System (INIS)

Watson, I.; Wilson, R.R.

1977-01-01

Safety and reliability are the most important factors of a nuclear power plant. This applies in particular to the circulators used to drive the high-density CO 2 around the reactor core and boiler circuits. Under operating conditions, very high sound-pressure levels are generated which could excite components and cause possible fatigue failures. Failures of this type were experienced on the original axial blowers for the Hinkley 'A' Magnox reactor and, following this, a stringent test plan was specified for the AGR circulators. The present paper describes some of the techniques used to measure strain, sound and vibration on circulators in a full-density rig. This rig reproduces the actual reactor working conditions of 300 0 C and 4.1 MN m -2 with gas velocities up to 120 m s -1 . Under these conditions sound-pressure levels of up to 172 dB are generated. This programme of circulator testing has continued for the past 10 years. During this period many obstacles and difficulties were encountered. Some of these problems, together with the solutions found, are discussed. (author)

To stay or to go? Balancing the risk of reprocessing plant control room evacuation following a criticality alarm

International Nuclear Information System (INIS)

Love, Suzanne; McCrindle, David; Harris, Neil; Haworth, Justin

2003-01-01

Following a criticality alarm within the Magnox Separation Plant at Sellafield, there is a conflict of interest between the risks associated with complete evacuation versus continued manning of the control room. The historic emergency response policy would be to completely evacuate the control room upon a criticality alarm. If, however, the alarm was found to be false, the inevitable loss in control over the plant could have environmental, operational and radiological release consequences. Maintaining control room manning following a genuine alarm might, however, result in an avoidable high dose to an operator. Based upon the estimated dose equivalent to a control room operator for a range of criticality incident morphologies a risk analysis was undertaken. The results indicate that the differential risk between an operator who evacuates immediately and an operator who remains for a short time to complete diagnostic checks is very small. As a consequence a new emergency policy was therefore developed on plant which results in a relatively low risk to control room operators, but still allows control over the plant to be retained following a false criticality alarm. (author)

Application of secondary and residual stresses to the assessment of the structural integrity of nuclear power-generating plant

International Nuclear Information System (INIS)

Banahan, B.D.

2008-01-01

Magnox nuclear power stations were built in the 1960s to design codes that, in general, required weldments to be subject to a post-weld heat treatment to remove residual stresses. Implicit in this was the assumption that the heat treatment reduced the stresses significantly such that as stated in the codes 'stresses caused by fabrication and welding are practically annulled'. However, it has since been realised that the stresses remaining, although small, could still be significant when incorporated into the subsequently developed failure avoidance methodologies such as R6. Moreover, either at the time of construction or during the operating life, repairs are undertaken to remove manufacturing or service-induced defects. These repairs can be put into service with or without a post-weld heat treatment. As a consequence of a paucity of data for the two- and three-dimensional distribution of the magnitude of these stresses, extremely conservative values of stresses have been adopted to ensure that the plant is secure against the design intent throughout the service life. In this paper, the requirements of the failure-avoidance methodology R6 Revision 4 are briefly reviewed with respect to the categorisation of secondary and residual stresses and the application of the three approaches for determining the as-welded residual stress distribution at room temperature. These three levels comprise, Level 1, simple estimates, Level 2, bounding profiles, and Level 3, detailed evaluation. Examples are presented where knowledge of the residual stresses has been an important component of the overall integrity assessment. The first relates to multi-pass weldments in superheater headers fabricated from a ferritic steel and the second to the weldments in the standpipes, both at Magnox power stations with concrete pressure vessels. Although in these cases the weldments had been subject to a post-weld heat treatment, the remaining residual stresses presented a significant challenge to

People, planet, prosperity - how a welsh nuclear generating site is tackling the challenge of sustainability

Energy Technology Data Exchange (ETDEWEB)

Jones, Iwan W.; Young, Einir M. [Welsh Institute for Natural Resources, Bangor University, Deiniol Road, Bangor, LL57 2UW (United Kingdom); JONES, JOHN IDRIS [Magnox North, Wylfa Site, Cemaes, LL67 0DH (United Kingdom)

2010-07-01

This paper will describe a Knowledge Transfer Partnership between Bangor University and Wylfa (a Magnox North generating site) to embed the wider principles of sustainability - 'beyond EHSS and Q' - into all the site's activities. Bangor University has created a sustainability health-check 'developed by academia but designed to bring understanding, innovation and culture change to businesses and other organisations on the ground'. This provided a starting point for the venture and gave Wylfa an opportunity to capture a snapshot of their current understanding of the dimensions and components of sustainable development, identifying strengths and weaknesses, and a chance to understand the interconnectedness of various activities - e.g. environmental health and safety, reducing risk, working to tight budgets, staff well-being, stakeholder engagement are all part of the same picture. In Wales, embedding sustainable development is a constitutional duty under Section 79 of the Government of Wales Act 2006. The current sustainable development scheme 'One Wales One Planet', launched on 22 May 2009 recognises that to achieve such aspirations a 'radical change is required in all sectors of society'. This has implications for the nuclear industry, especially at the dawn of a new build era, with regard to interactions with local authorities, supply chains and other stakeholders. Behavioural change is imperative, but how does this relate to the nuclear industry? Not only do we have to deliver on our core business with the obvious focus on risk management and environmental, health and safety and quality issues, but the site Director now finds him/herself being scrutinised on staff well-being, equality, diversity and equal opportunities, ethical trading, human rights, labour standards etc... All these may be 'good things' but there is a danger that this new obsession will divert attention from the core business. The findings

The rheology of oxide dispersions and the role of concentrated electrolyte solutions

International Nuclear Information System (INIS)

Biggs, Simon; Tindley, Amy

2007-01-01

Stability control of particulate dispersions is critical to a wide range of industrial processes. In the UK nuclear industry, significant volumes of waste materials arising from the corrosion products of Magnox fuel rods currently require treatment and storage. The majority of this waste is present as aqueous dispersions of oxide particulates. Treatment of these dispersions will require a variety of unit operations including mobilisation, transport and solid- liquid separation. Typically these processes must operate across a narrow optimal range of pH and the dispersions are, almost without exception, found in complex electrolyte conditions of high overall concentration. Knowledge of the behaviour of oxides in various electrolyte conditions and over a large pH range is essential for the efficient design and control of any waste processing approach. The transport properties of particle dispersions are characterised by the rheological properties. It is well known that particle dispersion rheology is strongly influenced by particle-particle interaction forces, and that particle-particle interactions are strongly influenced by adsorbed ions on the particle surfaces. Here we correlate measurements of the shear yield stress and the particle zeta potentials to provide insight as to the role of ions in moderating particle interactions. The zeta potential of model TiO 2 suspensions were determined (Colloidal Dynamics Zeta Probe) over a range of pH for a series of alkali metal halides and quaternary ammonium halides at a range of solution concentrations (0.001 M - 1 M). The results show some surprising co-ion effects at high electrolyte concentrations (>0.5 M) and indicate that even ions generally considered to be indifferent induce a shift in iso-electric point (i.e.p.) which is inferred as being due to specific adsorption of ions. The shear yield stress values of concentrated titania dispersions were measured using a Bohlin C-VOR stress controlled rheometer. The shear

People, planet, prosperity - how a welsh nuclear generating site is tackling the challenge of sustainability

International Nuclear Information System (INIS)

Jones, Iwan W.; Young, Einir M.; JONES, JOHN IDRIS

2010-01-01

This paper will describe a Knowledge Transfer Partnership between Bangor University and Wylfa (a Magnox North generating site) to embed the wider principles of sustainability - 'beyond EHSS and Q' - into all the site's activities. Bangor University has created a sustainability health-check 'developed by academia but designed to bring understanding, innovation and culture change to businesses and other organisations on the ground'. This provided a starting point for the venture and gave Wylfa an opportunity to capture a snapshot of their current understanding of the dimensions and components of sustainable development, identifying strengths and weaknesses, and a chance to understand the interconnectedness of various activities - e.g. environmental health and safety, reducing risk, working to tight budgets, staff well-being, stakeholder engagement are all part of the same picture. In Wales, embedding sustainable development is a constitutional duty under Section 79 of the Government of Wales Act 2006. The current sustainable development scheme 'One Wales One Planet', launched on 22 May 2009 recognises that to achieve such aspirations a 'radical change is required in all sectors of society'. This has implications for the nuclear industry, especially at the dawn of a new build era, with regard to interactions with local authorities, supply chains and other stakeholders. Behavioural change is imperative, but how does this relate to the nuclear industry? Not only do we have to deliver on our core business with the obvious focus on risk management and environmental, health and safety and quality issues, but the site Director now finds him/herself being scrutinised on staff well-being, equality, diversity and equal opportunities, ethical trading, human rights, labour standards etc... All these may be 'good things' but there is a danger that this new obsession will divert attention from the core business. The findings reported in this paper suggest that many of the actions

Safety and licensing: the British perspective

Energy Technology Data Exchange (ETDEWEB)

Anthony, R D

1986-02-01

The legal framework of British regulatory practice is described, with emphasis on its flexibility and the fact that responsibility rests with the licensee, leaving the NII to monitor his implementation of that duty. The UK regulatory philosophy, the mixture of selective and random sampling used and the organization of the regulatory bodies as it interacts with that of the nuclear industry are outlined. This is followed by a resume of the current nuclear safety issues and of the NII's attitude to them, including the continued operation of the aging Magnox reactors, the extended transition of the AGR from the prototype to the 'tried and tested' stage of its existence, the problems of licensing nuclear chemical plant, the CEGB's proposed introduction of the PWR into this country, the availability of increasingly sophisticated means of assessing safety, and the steadily rising public interest in nuclear power issues. The Lecture ends by noting the problems of risk perception and cost/benefit analysis, emphasizing that in striking the right balance the regulatory body must be open, prepared to justify its reasoning, and productive of conclusions which are acceptable to the public.

End of the nuclear dream. The UKAEA and its role in nuclear research and development

Energy Technology Data Exchange (ETDEWEB)

Flood, M

1988-01-01

The study sets out to assess the performance of the United Kingdom Atomic Energy Authority (UKAEA) and to make recommendations for its role in the future within the overall energy needs of the United Kingdom. It assumes that the Magnox stations will be phased out after 20-25 years service, that the Advanced Gas-Cooled reactors will be shut down after 20-25 years service and no more built and that perhaps five or so Pressurized Water reactors will be built by the year 2000, including the Sizewell-B station. The first part of the report traces the institutional changes that have taken place in the UKAEA from its formation in 1954 up to the late 1980s. The current structure of the UKAEA is described in part 2. Questions of accountability are raised and its dual role of assessor and promoter of nuclear power is questioned. Part three looks at the UKAEA's role in developing nuclear power, especially the economic implications. In part four fundamental errors of judgement by the UKAEA are blamed for the failure of the UK nuclear industry to provide cheap, abundant, electricity. Practical recommendations for a major restructuring of the Authority are made.

The effect of corrosion product colloids on actinide transport

International Nuclear Information System (INIS)

Gardiner, M.P.; Smith, A.J.; Williams, S.J.

1992-01-01

The near field of the proposed UK repository for ILW/LLW will contain containers of conditioned waste in contact with a cementious backfill. It will contain significant quantities of iron and steel, Magnox and Zircaloy. Colloids deriving from their corrosion products may possess significant sorption capacity for radioelements. If the colloids are mobile in the groundwater flow, they could act as a significant vector for activity transport into the far field. The desorption of plutonium and americium from colloidal corrosion products of iron and zirconium has been studied under chemical conditions representing the transition from the near field to the far field. Desorption R d values of ≥ 5 x 10 6 ml g -1 were measured for both actinides on these oxides and hydroxides when actinide sorption took place under the near-field conditions and desorption took place under the far-field conditions. Desorption of the actinides occurred slowly from the colloids under far-field conditions when the colloids had low loadings of actinide and more quickly at high loadings of actinide. Desorbed actinide was lost to the walls of the experimental vessel. (author)

Hinkley Point 'C' power station public inquiry: proof of evidence on emergency planning

International Nuclear Information System (INIS)

Western, D.J.

1988-09-01

A public inquiry has been set up to examine the planning application made by the Central Electricity Generating Board (CEGB) for the construction of a 1200 MW Pressurized Water Reactor power station at Hinkley Point (Hinkley Point ''C'') in the United Kingdom, adjacent to an existing nuclear power station incorporating Magnox and Advanced Gas Cooled reactors. The CEGB evidence to the Inquiry presented here introduces the concept of the Reference Accident as the basis for emergency arrangements. The description which follows of the emergency arrangements at the Hinkley Point site include: the respective responsibilities and their co-ordination of bodies such as the CEGB, external emergency services and government departments; the site emergency organization; practical aspects of the emergency arrangements; and consideration of the extension of the arrangements to a PWR on the same site. Recent developments in emergency planning, such as those arising out of post Chernobyl reviews and the Sizewell ''B'' PWR Inquiry, are taken into account. The conclusion is reached that soundly based emergency arrangements already exist at Hinkley Point which would require relatively minor changes should the proposed PWR be constructed. (UK)

Recent developments on in-reactor photography

International Nuclear Information System (INIS)

Clayton, R.; Jones, B.

1984-01-01

The bulk of nuclear reactor inspection is undertaken by CCTV survey. The immediacy of the results and the ability of this technique to scan large areas have obvious advantages. However for detailed inspection of particular components photography is preferred. Two problems beset in-reactor photography, these being radiation fogging of the film and the necessity to change the film in the camera. The former problem can be somewhat obviated by fast manipulator but only in relatively low radiation areas. The latter is more difficult to cope with since the constant removal of a camera to change film is operationally time consuming and also increases the total exposure of film to radiation. This paper describes a method which has recently been devised where film is transported to and from a pre-positioned camera at high speed both reducing drastically the exposure time to radiation and removing the need to extract the camera from the reactor in order to change the film. The full potential of this technique remained undeveloped until a need arose to photograph lower levels of core restraint in a Magnox reactor. (author)

Reactor accidents and the environment

International Nuclear Information System (INIS)

Beattie, J.R.; Griffiths, R.F.; Kaiser, G.D.; Kinchin, G.H.

1978-01-01

This is a condensed version of a paper, entitled 'The Environmental Impact of Radioactive Releases from Accidents in Nuclear Power Reactors', by the authors, presented to the Nuclear Energy Panel of the International Atomic Energy Agency/United Nations Environmental Programme. Headings include - Effects of ionising radiation on man; number of deaths expected from leukaemia and other cancers; risk estimates for incidence of benign nodules and thyroid cancer; maximum permissible levels and emergency levels of radiation and radioactivity; ICRP recommended dose limits for members of the general public; atmospheric dispersion and modelling; ICRP emergency reference levels for 1 131 , Cs 137 , Ru 106 and Sr 90 ; environmental consequences of accidental releases from nuclear power reactors; environmental impact of accidents to Magnox gas-cooled reactors; environmental impact of accidents to advanced gas-cooled reactors; environmental impact of accidents to fast reactors; and nature of risks. consequences are examined in terms of early and late biological effects on man, and contamination of land areas. Serious accidents are of low probability of occurrence, and the risk of accidents to nuclear power reactors is estimated to be very small. 43 references. (U.K.)

Ichthyoplankton entrainment at Wylfa power station, Anglesey and implications for a further siting proposal

International Nuclear Information System (INIS)

Dempsey, C.H.; Rogers, S.I.

1989-07-01

A 12 month survey of ichthyoplankton in the cooling water system of Wylfa Power Station and the surrounding 40 km 2 of sea, was carried out between October 1986 and September 1987. The larvae of 31 species and the eggs of 8 species were identified in the survey. Samples taken from the cooling water system and by boat from offshore were largely similar in respect of species diversity and density. Estimates of annual losses due to entrainment are given both in terms of immediate losses and consequential losses of adults to the population. Estimates of losses of six commercially exploited species are considered in terms of loss to the commercial fishery. Assuming the 'worst case' of a 100% mortality of eggs and larvae passing through the cooling system, losses of ichthyoplankton due to entrainment at the existing 'magnox' nuclear power station at Wylfa Point are small and could have no significant adverse effect on fish populations of those species entrained. The operation of the proposed 'pressurised water reactor' nuclear power station on the same site would increase losses by up to 100%. Such an increase would still not alter the existing situation. No significant adverse effect is likely. (author)

The response of film badge dosemeters to high energy photon radiation

International Nuclear Information System (INIS)

Playle, T.S.

1988-12-01

The sites of the earlier magnox reactor power stations at Berkeley and Bradwell in the United Kingdom are subject to 6 MeV photon radiation from the coolant gas. Since 1966 the Central Electricity Generating Board has included in its film badge personal dosimetry procedures an algorithm for applying a correction for over-response to high energy photon radiation. The correction is based on laboratory irradiations using a source of pure 6 MeV photon radiation. Recently, the opportunity arose to evaluate the response of the film badges at locations around the Berkeley reactors where spectrum-dependent dose equivalent rates had been measured. This report compares the response of the film badge in these characterised radiation environments with the response measured in the calibration laboratory. It is concluded that in the location where measurements were made, the high energy enhancement of measured dose was obscured by the effects of low energy scattered radiation, and it is considered that this will be the case for all practical situations on the power station site. There is therefore no advantage in using the 6 MeV correction factors for routine film badge dosimetry in these locations. (author)

From Core to Capture: Graphite Management by Gasification and Carbon Capture & Storage (CCS)

International Nuclear Information System (INIS)

Goodwin, J.; Bradbury, D.; Black, S.; Tomlinson, T.; Livesey, B.; Robinson, J.; Lindberg, M.; Newton, C.; Jones, A.; Wickham, A.

2016-01-01

Radioactive graphite waste arises principally from the moderators of graphite/gas-cooled reactors at the end of life of the reactors. Commercial power producing reactors (for example, Magnox, AGR and RBMK) have graphite moderators, each containing several thousand tonnes of graphite, with the UK having the largest inventory of over 90,000 tonnes. Additionally, there are smaller quantities of graphite arising from other sources such as fuel element components. The current long term strategy for management of reactor graphite in the UK is for these wastes to be conditioned for disposal followed by transfer to a geological disposal facility (GDF). With this baseline position, these wastes will account for about 30% of the ILW inventory in a GDF. As the volume of the graphite waste is so large, it is not currently economic to retrieve and process the graphite in advance of the availability of a geological disposal facility. Recent work by the NDA has ascribed a much smaller “incremental” volume of 2% due to graphite, calculated on the basis that the GDF has to be a certain size anyway in order to dissipate the decay heat from high level waste

Assessment of management modes for graphite from reactor decommissioning

International Nuclear Information System (INIS)

White, I.F.; Smith, G.M.; Saunders, L.J.; Kaye, C.J.; Martin, T.J.; Clarke, G.H.; Wakerley, M.W.

1984-01-01

A technological and radiological assessment has been made of the management options for irradiated graphite wastes from the decommissioning of Magnox and advanced gas-cooled reactors. Detailed radionuclide inventories have been estimated, the main contribution being from activation of the graphite and its stable impurities. Three different packaging methods for graphite have been described; each could be used for either sea or land disposal, is logistically feasible and could be achieved at reasonable cost. Leaching tests have been carried out on small samples of irradiated graphite under a variety of conditions including those of the deep ocean bed; the different conditions had little effect on the observed leach rates of radiologically significant radionuclides. Radiological assessments were made of four generic options for disposal of packaged graphite: on the deep ocean bed, in deep geologic repositories at two different types of site, and by shallow land burial. Incineration of graphite was also considered, though this option presents logistical problems. With appropriate precautions during the lifetime of the Cobalt-60 content of the graphite, any of the options considered could give acceptably low doses to individuals, and all would merit further investigation in site-specific contexts

An assessment of filter aids and filter cloths in the dewatering of intermediate level wastes

International Nuclear Information System (INIS)

Knibbs, R.H.; Hudson, B.C.; Blackwell, J.C.W.

1984-12-01

This report considers a range of filter cloths and precoat materials intended for use in dewatering intermediate level radioactive wastes, and their interaction when used on a rotary drum vacuum filter. The report outlines the advantages and disadvantages of various grades and types of precoat and shows that grades with permeabilities in the intermediate range, 3 to 4 x 10 -12 m 2 , give satisfactory filtrate quality together with ease of operation. The work on filter cloths shows that: radiation damage is not a limiting factor as regards operational life for any of the cloths examined; polyester-based cloths are unsuitable due to their poor resistance to alkali attack; polyamide cloths are satisfactory; and stainless steel Dutch weave cloths are satisfactory and have the added advantage of high strength. The report also briefly considers the radiation resistance of two elastomeric membranes used on the 'epidermal' filter and shows that the natural latex rubber membrane is considerably more resistant to radiation than the silicone rubber membrane and has an estimated operational life of at least 1200 hours when dewatering Magnox silo sludge or α-contaminated alumino ferric flocs. (author)

EPDM and fluorocarbon seal materials: a comparison of performance for nuclear fuel transport flasks

International Nuclear Information System (INIS)

Chivers, T.C.; George, A.F.

2004-01-01

The lid seals on the flasks used to transport spent fuel from U.K. AGR and Magnox Power Stations are fluorocarbon elastomer 'O' rings. Currently, only this material is qualified for the purpose and it was decided to investigate the possibility of qualifying other materials. One material that is already in use in similar applications is an Ethylene Propylene Diene Monomer (EPDM). The work presented in this paper compares the performance of the existing material with three candidate types of EPDM. The areas considered were: Extrusion and blow-out resistance when subjected to various steam pressures and temperatures at a range of flange separations, Permeability to water, caesium salt solution and hydrogen (as a typical 'benchmark' gas) Radiation resistance in warm (60 C) aqueous conditions It is concluded that the performance of the EPDM materials is good in respect of mechanical properties, radiation and water resistance. However, while permeation rates for gas and water can be higher than for fluorocarbon, this might be mitigated by assessing the actual radioactive burden in the permeate. In the case of dissolved salts, the test results indicate that this will be very low

MethodS of radioactive waste processing and disposal in the United Kingdom

International Nuclear Information System (INIS)

Tolstykh, V.D.

1983-01-01

The results of investigations into radioactive waste processing and disposal in the United Kingdom are discussed. Methods for solidification of metal and graphite radioactive wastes and radioactive slime of the Magnox reactors are described. Specifications of different installations used for radioactive waste disposal are given. Climatic and geological conditions in the United Kingdom are such that any deep storages of wastes will be lower than the underground water level. That is why dissolution and transport by underground waters will inevitably result in radionuclide mobility. In this connection an extended program of investigations into the main three aspects of disposal problem namely radionucleide release in storages, underground water transport and radionuclide migration is realized. The program is divided in two parts. The first part deals with retrival of hydrological and geochemical data on geological formations, development of specialized methods of investigations which are necessary for identification of places for waste final disposal. The second part represents theoretical and laboratory investigations into provesses of radionuclide transport in the system of ''sttorage-geological formation''. It is concluded that vitrification on the base of borosilicate glass is the most advanced method of radioactive waste solidification

Overview of the older nuclear power stations in the world

International Nuclear Information System (INIS)

Fuchs, H.; Zuend, H.

1991-01-01

The oldest reactors in the world which are still operative are of the Magnox type. These will probably reach that 'useful' service life of 40 years over the next 6 - 10 years and will then be closed down. Light water reactors will not reach this age for another 10 - 15 years since the vast majority of the first pioneering systems have already been closed down. However, these created the preconditions for later systems to achieve service lives of 40 years or more. A consideration of the ageing mechanisms of reactors shows that 'old' is not a suitable criterion for taking a decision as to whether a reactor should be shut down or not. The major criterion for a decision of this kind is safety. Older plants in particular, often have large reserves so that the safety targets can still be maintained even after the useful service life has expired by simply adding sensible equipment. What constitutes 'sensible' equipment must also be considered from a financial point of view. The important thing is that each case requires individual consideration. 1 fig., 4 tabs., 12 refs

Worker exposures: How much in the UK

International Nuclear Information System (INIS)

Shaw, K.B.

1985-01-01

Basically, four categories of workers are involved with transport operations: handlers, drivers, health physics monitoring staff, and supervisory staff. In 1984, the National Radiological Protection Board (NRPB) published results of a study covering all four of these worker categories, all types of radioactive material, and all modes of transport used in the United Kingdom. The study covered occupationally related exposure during all normal transport operations of radioactive materials, but did not cover potential consequences of accidents. Although mainly concerned with exposure of workers, the study included the exposure of the public from the transport of irradiated Magnox fuel from the first generation of nuclear power stations. The current evaluation - based on measurements as distinct from earlier assessments which were theoretical estimates - shows that the public exposure is much lower than the calculated maximum based on pessimistic assumptions. For workers, the study concluded that the annual collective dose from the transport of all radioactive materials in the UK is approximately 1 man-sievert. This compares with an annual collective dose estimated at 500 man-sievert from all occupational exposure to ionizing radiation in the UK

A Review of Past Reactor Progress in the UK, April 1975

International Nuclear Information System (INIS)

Smith, R.D.

1975-01-01

The fast reactor project in the UK is continuing at approximately the same scale of effort as last year, with great attention being paid to overcoming the difficulties being met in raising PFR to full power. Organisational arrangements for nuclear power in the UK during the year have been dominated by two interlinked issues, firstly the choice of thermal reactor system for the next stage of the British nuclear power programme, and secondly the consolidation of the British nuclear design and construction industry. On the former, widespread discussion on the merits of alternative thermal systems culminated in the announcement by the Secretary of State for Energy on 10 July 1974 that the British electricity boards would adopt the SGHWR for their next nuclear power station orders. The initial ordering programme was set at 4000 KW(E) over the next four years, with the prospect of extending the programme in the later 1970s given satisfactory initial experience of construction. Consent has now been given by the Department of Energy to the CEGB for an SGHWR station at Sizewell in Suffolk (adjacent to an existing Magnox station) and to the SSEB for one at Torness Point in East Lothian

Development and radiation stability of glasses for highly radioactive wastes

International Nuclear Information System (INIS)

Hall, A.R.; Dalton, J.T.; Hudson, B.; Marples, J.A.C.

1976-01-01

The variation of formation temperature, crystallizing behaviour and leach resistance with composition changes for sodium-lithium borosilicate glasses suitable for vitrifying Magnox waste are discussed. Viscosities have been measured between 400 and 1050 0 C. The principal crystal phases which occur have been identified as magnesium silicate, magnesium borate and ceria. The leach rate of polished discs in pure water at 100 0 C does not decrease with time if account is taken of the fragile siliceous layer that is observed to occur. The effect of 100 years' equivalent α- and β-irradiation on glass properties is discussed. Stored energy release experiments demonstrated that energy is released over a wide temperature range so that it cannot be triggered catastrophically. Temperatures required to release energy are dependent upon the original storage temperature. Helium release is by Fick's diffusion law up to at least 30% of the total inventory, with diffusion coefficients similar to those for comparable borosilicate glasses. Leach rates were not measurably affected by α-radiation. β-radiation in a Van de Graaff accelerator did not change physical properties, but irradiation in an electron microscope caused minute bubbles in lithium-containing glasses above 200 0 C. (author)

Cleanup Progress on High Hazard Legacy Facilities at Sellafield: Pile Fuel Cladding Silo

International Nuclear Information System (INIS)

Skilbeck, D.

2006-01-01

This facility was constructed in the 1940's as the original dry storage silo for Intermediate Level Waste (ILW) arising from the Windscale Pile Reactors. Subsequently it was used as the main storage facility for all ILW arising from the Sellafield operation. It was operated until it became full and the Magnox Swarf Storage Silos were constructed in the mid 1960's. A systematic and As Low As Reasonably Practicable (ALARP) risk reduction approach has been adopted at Sellafield to address issues in order of risk magnitude. Prior to being in a position to retrieve stored wastes it has been necessary to improve the overall safety performance of the silo. This has involved installing new fire prevention systems, improving structural integrity, clearing waste from the Transfer Tunnel, and improving overall seismic performance. A major step towards reducing the overall risk profile of this facility has been to seal the six charge holes in the Transfer Tunnel, that were used for tipping the waste into the silo compartments during operations. This also enabled the silo Transfer Tunnel to be removed. Overall this work has proved that significant cleanup can be performed safely and successfully, in one of the most hazardous environments at Sellafield. (authors)

The nuclear review

International Nuclear Information System (INIS)

Hawley, R.

1994-01-01

The United Kingdom Government's Review of the prospects for nuclear power, which commenced in May 1994, has terms of reference in which four key issues are identified. These are: whether privatisation is possible and on what timescale; the most cost-effective management of the public sector's liabilities; whether new nuclear stations can be built on a commercial basis and with private finance; and what particular benefits or disadvantages nuclear power has with respect to diversity, security of supply and environmental impacts. The response of Nuclear Electric to these issues is summarized. The Company believes that the financial obstacles to privatisation which existed when it was established in 1989 have been largely overcome and that privatisation now provides it with the best competitive opportunity in today's electricity market. Significant progress has been made in reducing and quantifying the financial liabilities associated with waste management and reactor decommissioning. To secure its future, Nuclear Electric must be allowed to build new plants to replace the 2500 MW(e) of Magnox capacity which will retire by the end of the century. Longer term wider policy objectives should also take account of the fact that during the last twelve months alone, Nuclear Electric has saved the emission of 60 million tonnes of carbon dioxide. (UK)

The Liabilities Management Group

International Nuclear Information System (INIS)

Whitehead, A.W.

1998-01-01

The Liabilities Management Group (LMG) was initiated by DTI. It is a cooperative forum which was set up in 1995. The current participants are DTI, UKAEA, NLM (for BNFL), MOD and Magnox Electric. The LMG was initiated to produce closer cooperation between public sector liability management organizations, achieve more cost-effective management of UK nuclear liabilities and enhance development of the UK nuclear decommissioning and waste management strategy. The objectives are to compare practices between liabilities management organizations discuss the scope for collaboration identify priority areas for possible collaboration agree action plans for exploring and undertaking such collaboration.Four task forces have been formed to look at specific areas (R and D, safety, contracts, and project management) and each reports separately to the LMG. The LMG has achieved its original aim of bringing together those with public sector liability management responsibilities. All participants feel that the LMG has been useful and that it should continue. Looking to the future, there is a continuing need for the LMG to facilitate removal of barriers to the achievement of best value for money. The LMG might also consider addressing the 'business process' elements that a liability management organization must be good at in order to define best practice in these. (author)

Improved estimates of external gamma dose rates in the environs of Hinkley Point Power Station

International Nuclear Information System (INIS)

Macdonald, H.F.; Thompson, I.M.G.

1988-07-01

The dominant source of external gamma dose rates at centres of population within a few kilometres of Hinkley Point Power Station is the routine discharge of 41-Ar from the 'A' station magnox reactors. Earlier estimates of the 41-Ar radiation dose rates were based upon measured discharge rates, combined with calculations using standard plume dispersion and cloud-gamma integration models. This report presents improved dose estimates derived from environmental gamma dose rate measurements made at distances up to about 1 km from the site, thus minimising the degree of extrapolation introduced in estimating dose rates at locations up to a few kilometres from the site. In addition, results from associated chemical tracer measurements and wind tunnel simulations covering distances up to about 4 km from the station are outlined. These provide information on the spatial distribution of the 41-Ar plume during the initial stages of its dispersion, including effects due to plume buoyancy and momentum and behaviour under light wind conditions. In addition to supporting the methodology used for the 41-Ar dose calculations, this information is also of generic interest in the treatment of a range of operational and accidental releases from nuclear power station sites and will assist in the development and validation of existing environmental models. (author)

News on the development of nuclear energy in Great Britain

International Nuclear Information System (INIS)

Oppenfeld, M. von

1991-01-01

Governmental influence on public utilities and on the government-controlled nuclear industry so far has been much stronger than in the Federal Republic. This influence was cut back considerable when denationalization pursuant to the Electricity Act 1989 took effect, but not for the nuclear industry. Despite governmental declarations to the contrary, the big reactor building program has shrunk to one started reactor being finished. The reasons for turning away from nuclear energy are not so much to be found with the greens, who have little influence because of majority suffrage, but with orientating at short-term maximization of profits as a result of the denationalization process which prevents at present the realization of financing large-scale projects in the field of nuclear energy on a long-term basis. With the Magnox reactors coming to the end of their working life and neither coal-fired power stations nor nuclear power plants being built, with the exception of Sizewell II, this situation will sooner or later lead to an out-of-date power plant pool, and considerations concerning power plant capacities (including nuclear reactors) will become necessary. As regards reprocessing, the abandonment of Wackersdorf has led to the Internal Market being already anticipated by long-term contracts concluded with BNF. (orig./HSCH) [de

The Storage of Power Development and Research Reactor Fuel at Sellafield

International Nuclear Information System (INIS)

Standring, P.N.; Callaghan, A.H.C.

2009-01-01

Sellafield Limited has extensive experience of building and operating spent nuclear fuel storage facilities on the Sellafield site. Since the first operation in 1952, a total of six storage facilities have been built in support of reprocessing spent fuel. Currently, four of these facilities are operational and two are undergoing decommissioning activities. Whilst the routine spent fuel operations are primarily associated with managing Magnox, Advanced Gas Reactor and LWR fuel from power generation reactors, management services to other fuel types are offered. Examples of these services include the storage of British naval training reactor fuel; the reprocessing of two skips of aluminium clad uranium metal fuel from Swedish AB SVAFO and the management of fuel from the UK Power Development Programme. The current paper provides an account of the management of the UK's Power Development Programme fuel stored on the Sellafield site. The fuel has been pond stored for up to 42 years and periodic inspection during this time has revealed no significant deterioration of the fuel, particularly that which has been containerised during its storage period. The paper also outlines some of the issues associated with the recovery and transfer of long stored fuel and assessment of the fuel storage can longevity if the material is not reprocessed. (author)

Wylfa nuclear boiler repair. How a major problem was solved

International Nuclear Information System (INIS)

1977-09-01

The CEGB has published a booklet, with coloured illustrations, that describes in detail the story of an unusually difficult boiler repair on a Magnox reactor at Wylfa nuclear power station. Boiler leaks affected the operation of No. 2 reactor in 1972, and persisted during 1973. A special procedure was developed for plugging the leaks using a remote welding machine but with the incidence of leaks continuing attempts were made to obtain a specimen of leaking tube by cutting through the boiler support tank to gain access. Eventually the fault was then traced to excessive relative motion between the tubes and support clips. Remedial work took seven months and was completed in December 1975. The start of the problem and the method of plugging the leaks is described. Details are given of the investigation leading to the obtaining and examination of a sample of leaking tube and the determination of the fault. Establishment of the cause as an unusual form of resonant vibration causing wear and fretting in clip-to-tube positions in the economiser region of the boiler is described in detail. The difficulties and accomplishments of the repair work are detailed. Finally the operation is looked at in retrospect and the experiences gained are summarised. (UK)

Radioactive waste package assay facility. Volume 2. Investigation of active neutron and active gamma interrogation

International Nuclear Information System (INIS)

Bailey, M.; Bunce, L.J.; Findlay, D.J.S.; Jolly, J.E.; Parsons, T.V.; Sene, M.R.; Swinhoe, M.T.

1992-01-01

Volume 2 of this report describes the theoretical and experimental work carried out at Harwell on active neutron and active gamma interrogation of 500 litre cemented intermediate level waste drums. The design of a suitable neutron generating target in conjunction with a LINAC was established. Following theoretical predictions of likely neutron responses, an experimental assay assembly was built. Responses were measured for simulated drums of ILW, based on CAGR, Magnox and PCM wastes. Good correlations were established between quantities of 235 -U, nat -U and D 2 O contained in the drums, and the neutron signals. Expected sensitivities are -1g of fissile actinide and -100g of total actinide. A measure of spatial distribution is obtainable. The neutron time spectra obtained during neutron interrogation were more complex than expected, and more analysis is needed. Another area of discrepancy is the difference between predicted and measured thermal neutron flux in the drum. Clusters of small 3 He proportional counters were found to be much superior for fast neutron detection than larger diameter counters. It is necessary to ensure constancy of electron beam position relative to target(s) and drum, and prudent to measure the target neutron or gamma output as appropriate. 59 refs., 77 figs., 11 tabs

The assessment of environmental consequences of nuclear reactor accidents

International Nuclear Information System (INIS)

Beattie, J.R.

1981-01-01

Thorough measures are taken throughout all stages of design, construction and operation of nuclear power reactors, and therefore no accident producing any significant environmental impact is likely to occur. Nevertheless as a precaution, such accidents have been the subject of intensive scientific predictive studies. After a historical review of theoretical papers on reactor accidents and their imagined environmental impacts and of those accidents that have indeed occurred, this paper gives an outline of fission products or other radioactive substances that may or may not be released by an accident, and of their possible effects after dispersion in the atmosphere. This general introduction is followed by sections describing what are sometimes called 'design basis accidents' for four of the main reactor types (magnox, AGR, PWR and CDFR), the precautions against these accidents and the probable degree of environmental impact likely. The paper concludes with a reference to those very low probability accidents which might have more serious environmental impacts, and proceeds from there to show that both the individual and community risks from such accidents are numerically moderate compared to other risks apparently accepted by society. A brief reflection on the relevance of numerical values and perceived risk concludes the paper. (author)

Long-term storage of spent nuclear fuel

International Nuclear Information System (INIS)

Kempe, T.F.; Martin, A.; Thorne, M.C.

1980-06-01

This report presents the results of a study on the storage of spent nuclear fuel, with particular reference to the options which would be available for long-term storage. Two reference programmes of nuclear power generation in the UK are defined and these are used as a basis for the projection of arisings of spent fuel and the storage capacity which might be needed. The characteristics of spent fuel which are relevant to long-term storage include the dimensions, materials and physical construction of the elements, their radioactive inventory and the associated decay heating as a function of time after removal from the reactor. Information on the behaviour of spent fuel in storage ponds is reviewed with particular reference to the corrosion of the cladding. The review indicates that, for long-term storage, both Magnox and AGR fuel would need to be packaged because of the high rate of cladding corrosion and the resulting radiological problems. The position on PWR fuel is less certain. Experience of dry storage is less extensive but it appears that the rate of corrosion of cladding is much lower than in water. Unit costs are discussed. Consideration is given to the radiological impact of fuel storage. (author)

The prospects for nuclear power in the UK. Conclusions of the Government's nuclear review

International Nuclear Information System (INIS)

1995-05-01

The conclusions of the United Kingdom government's review of the nuclear industry in Britain were presented to Parliament in May 1995. The provision of public sector support for a new nuclear power station is deemed unwarranted against the background of the current electricity market. In reaching this conclusion the government considered possible environmental and strategic advantages, the question of diversity of fuel sources, and wider economic benefits. It is intended to privatize parts of Nuclear Electric and Scottish Nuclear in 1996 as subsidiaries of a single holding company to take over the UK's AGR and PWR stations together with a significant level of their associated liabilities. A publicly owned company will continue to run the magnox stations and retain their liabilities. British Nuclear Fuels Ltd (BNFL) will continue to offer nuclear fuel services and to receive government support in developing business in overseas markets. Since their formation in 1990, Nuclear Electric and Scottish Nuclear have improved their financial performance significantly. At privatisation the nuclear component of the fossil fuel levy will cease to be paid to Nuclear Electric and Scottish Nuclear will no longer receive the current premium price paid under the Nuclear Energy Agreement. The current regulatory regime and rigorous safety standards for nuclear power will remain substantially unchanged. (UK)

The United Kingdom

International Nuclear Information System (INIS)

Jones, P.M.S.

1987-01-01

The history of nuclear development in the United Kingdom is traced, together with the factors (eg electricity demand, fossil fuel prices, political policy) that have influenced policy choices. Many of the research establishments and the fissile material production plants were established in the late 1940s. In these early years the civil and military development programmes were not separate. The initial growth period was in the 1950s when the plan was to build twelve reactors in three groups of four over ten years. The first were to be Magnox type reactors. This was trebled in 1957 and the advanced gas cooled reactor was developed. The Windscale fire in 1957 affected confidence in the nuclear programme. However, five AGR twin-reactor stations were ordered in 1964. These ran into construction problems and delay and it was not until 1980 that more new units were contemplated. The plan then was to build a pressurized water reactor at Sizewell-B. A delay to allow for the public inquiry put back the start of this until 1987 with commissioning planned for 1994. A list of the UK nuclear power stations is given and their operating performance discussed. The present situation and future prospects for nuclear power are reviewed. (U.K.)

LWR-plants. Their evolutionary progress in the last half-century. (4) The start of the nuclear power generation in Japan

International Nuclear Information System (INIS)

Ishikawa, Hiroshi

2008-01-01

Evolutionary progress of the LWR plants in the last half-century was reviewed in series. The start of the nuclear power generation in Japan was reviewed in this article. The Japan Atomic Energy Research Institute (JAERI) promoted nuclear power research and development and introduced the Japan Power Demonstration Reactor (JPDR)-a 12.5 MWe natural circulation BWR, which began operation in 1965. In 1969 its power uprate modifications to a forced circulation BWR (JPDR-II) began and attained operation in 1972. During 50% power test, primary coolant leakage was observed at reactor core spray pipes in 1972. In 1975 the operation resumed and faults observed at condenser tubes in 1976. Primary coolant leakage from in-core flux monitor guide tubes at the bottom of reactor pressure vessel in 1979 led to its permanent shutdown. The nuclear ship Mutsu was put into service in 1970 and during rising power test radiation leakage due to fast neutron streaming was observed in 1974. After modifications of shielding experimental voyage was made in 1991. The first commercial nuclear power reactor, Tokai-1-a 166 MWe gas-cooled (Magnox) reactor, began operation in 1966 and continued until 1998. The LWR plants became the mainstay in Japan. (T. Tanaka)

Safety audit of BNFL Sellafield 1986

International Nuclear Information System (INIS)

1986-01-01

The BNFL Sellafield site involved is the complex of buildings concerned with reprocessing spent nuclear fuel from the UK Magnox reactors. It includes facilities for the receipt and storage underwater of spent fuel from the power stations, the subsequent chemical separation of re-usable elements of uranium and plutonium from the radioactive waste, storage of the more radioactive of these wastes on the site and discharge to sea or atmosphere, or disposal at the nearby Drigg site of those wastes which are of very low-radioactive content. The audit (conducted in 1986) was undertaken to establish the physical state of the plant, to investigate the management policies and priorities and the supporting advisory structure and to determine the cause and severity of incidents (eg leaks) by a comprehensive study of those occuring since 1979. Some buildings have been studied in more detail than others. Volume 1 of the audit report covers details of how the audit was planned and carried out, the engineering audit, a review of procedures, an analysis of incidents, the findings as to the actions that need to be taken by BNFL, a general summary and the conclusions. Volume 2 contains more technical and detailed papers relating to the inspection on which the judgements presented in Volume 1 are based. (U.K.)

The decision on the application to carry out a decommissioning project at Hinkley Point A Power Station under the Nuclear Reactors (Environmental Impact Assessment for Decommissioning) Regulations 1999

International Nuclear Information System (INIS)

2003-01-01

European Council Directive 85/337/EEC, as amended by Council Directive 97/1 I/EC, sets out a framework on the assessment of the effects of certain public and private projects on the environment. The Directive is implemented in Great Britain for decommissioning nuclear reactor projects by the Nuclear Reactors (Environmental Impact Assessment for Decommissioning) Regulations 1999. The intention of the Directive and Regulations is to involve the public through consultation in considering the potential environmental impacts of a decommissioning project, and to make the decision-making process on granting consent open and transparent. The Regulations require the licensee to undertake an environmental impact assessment, prepare an environmental statement that summarises the environmental effects of the project, and apply to the Health and Safety Executive (HSE) for consent to carry out a decommissioning project. There is an optional stage where the licensee may request from HSE an opinion on what the environmental statement should contain (called a pre-application opinion). The licensee of Hinkley Point A Power Station, Magnox Electric pie, requested a pre-application opinion and provided information in a scoping report in December 2000. HSE undertook a public consultation on the scoping report and provided its pre- application opinion in April 2001. The licensee applied to HSE for consent to carry out a decommissioning project and provided an environmental statement in December 2001. Following a public consultation on the environmental statement, HSE requested further information that was subsequently provided by the licensee. A further public consultation was undertaken on the further information that ended in March 2003. All these public consultations involved around 60 organisations. HSE granted consent to carry out a decommissioning project at Hinkley Point A Power Station under the Regulations in July 2003, and attached conditions to the Consent. HSE took relevant

Behavior of spent nuclear fuel and storage system components in dry interim storage.

Energy Technology Data Exchange (ETDEWEB)

Johnson, A.B. Jr.; Gilbert, E.R.; Guenther, R.J.

1982-08-01

Irradiated nuclear fuel has been handled under dry conditions since the early days of nuclear reactor operation, and use of dry storage facilities for extended management of irradiated fuel began in 1964. Irradiated fuel is currently being stored dry in four types of facilities: dry wells, vaults, silos, and metal casks. Essentially all types of irradiated nuclear fuel are currently stored under dry conditions. Gas-cooled reactor (GCR) and liquid metal fast breeder reactor (LMFBR) fuels are stored in vaults and dry wells. Certain types of fuel are being stored in licensed dry storage facilities: Magnox fuel in vaults in the United Kingdom and organic-cooled reactor (OCR) fuel in silos in Canada. Dry storage demonstrations are under way for Zircaloy-clad fuel from boiling water reactors BWR's, pressurized heavy-water reactors (PHWRs), and pressurized water reactors (PWRs) in all four types of dry storage facilities. The demonstrations and related hot cell and laboratory tests are directed toward expanding the data base and establishing a licensing basis for dry storage of water reactor fuel. This report reviews the scope of dry interim storage technology, the performance of fuel and facility materials, the status of programs in several countries to license dry storage of water reactor fuel, and the characteristics of water reactor fuel that relate to dry storage conditions.

Graphite core stability during 'care and maintenance' and 'safe storage'

International Nuclear Information System (INIS)

Wickham, A.J.; Marsden, B.J.; Sellers, R.M.; Pilkington, N.J.

1998-01-01

The current decommissioning strategy for the graphite-moderated reactors operated by Magnox Electric plc, Nuclear Electric Ltd and Scottish Nuclear Ltd is to delay dismantling and to initiate a monitored period of care and maintenance followed by a period of safe storage totaling up to 135 years. This philosophy has the considerable advantage of permitting the majority of radionuclides to decay, thereby minimising personnel dose during dismantling which itself will require far less complex remote-handling equipment. It also defers the disposal of the graphite and other components so that the provision of a deep land-based repository can be achieved. A comprehensive review of all relevant data on the chemical, physical and mechanical properties of the graphite and its potential reactions, including radioactivity transport, has been undertaken in order to demonstrate that there are no potential mechanisms which might lead to degradation of the core during the storage period. It is concluded that no significant experimental work is necessary to support the safe storage philosophy although, since the ingress of rainwater over long periods of time cannot be assumed incredible, a number of anomalies in chemical leaching rates may be worthy of re-examination. No other potential chemical reactions, such as the radiolytic formation of nitric acid leading to corrosion problems, are considered significant. (author)

Remote technology: a series of articles

International Nuclear Information System (INIS)

Meieran, H.B.

1987-01-01

A series of articles on the use of remote technology in the nuclear industry. A worldwide survey of mobile robots suitable for actual or proposed use in nuclear facilities is presented. Details are given of the first Robot Users Group, recently formed in the U.S.A. Robots with artificial intelligence are under development at Tokyo Electric Power Company. Kansai Electric Power and Toshiba are two companies conducting RandD to further the application of robots. Westinghouse have used the Rosa robotic arm in zero-entry steam generator tube sleeving projects, and are now looking at further developments. The 'Warrior' manipulator, by Taylot Hitec, has conducted the first continuous path MIG weld inside a magnox reactor. The articulated boom for the JET fusion device can lift 1t. at full extension. The Savannah River Laboratory is studying an advanced intelligent machine which could lead to the introduction of legged mobile and multi-tasking teleoperated work stations. Plans are being made to equip the Surveyor mobile surveillance system at Nine Mile Point with a number of tools. Frastar, developed by Framatome, is a vehicle which can operate inside the containment of a reactor in operation or in hazardous areas. The mobile surveillance robot, Surbot, developed by Remotec, has successfully completed five months of testing at Browns Ferry BWR. (author)

Some UK experience and practice in the packaging and transport of irradiated fuel

International Nuclear Information System (INIS)

Edney, C.J.; Rutter, R.L.

1977-01-01

The origin and growth of irradiated fuel transport within and to the U.K. is described and the role of the organisations presently carrying out transport operations is explained. An explanation of the relevant U.K. regulations and laws affecting irradiated fuel transport and the role of the controlling body, the Department of the Environment is given. An explanation is given of the technical requirements for the transport of irradiated Magnox fuel and of the type of flask used, and the transport arrangements, both within the U.K. and to the U.K., from overseas is discussed. The technical requirements for the transport of C.A.G.R. fuel are outlined and the flask and transport arrangements are discussed. The transport requirements of oxide fuel from water reactors is outlined and the flask and shipping arrangements under which this fuel is brought to the U.K. from overseas is explained. The shipping arrangements are explained with particular reference to current international and national requirements. The requirements of the transport of M.T.R. fuel are discussed and the flask type explained. The expected future expansion of the transport of irradiated fuel within and to the U.K. is outlined and the proposed operating methods are briefly discussed. A summary is given of the U.K. experience and the lessons to be drawn from that experience

Annual report on operation, utilization and technical development of hot laboratories. From April 1, 1996 to March 31, 1997

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-02-01

This report describes activities, in fiscal year 1996, of the Reactor Fuel Examination Facility (RFEF), the Research Hot Laboratory (RHL) and the Waste Safety Testing Facility (WASTEF) which belong to the Department of Hot laboratories. In the RFEF, Post-Irradiation Examinations (PIEs) of PWR fuel assemblies irradiated in the Takahama Unit 3, a BWR fuel assembly irradiated in the Fukusima Daini Unit have been performed. Also, PIEs of assembly materials irradiated in the Fugen Reactor have been carried out. To support R and D works in JAERI, refabrication of segmented fuel rods have been done using irradiated LWR fuel rods for pulse irradiation in the NSRR and re-irradiation tests in the JMTR. PIEs have been performed on high burnup fuel rods and ROX fuel rods. For the RHL, PIEs have been performed on segment fuels irradiated in the NSRR, fuels and materials for HTTR, standard fuels for JRR-3M and materials for nuclear fusion reactor. In addition, a monitoring test of fuel elements in accordance with the surveillance program of the Magnox reactor of the Japan Atomic Power Corporation has been continued. In the WASTEF, leaching tests on TRU in simulated glass forms and a low flow rate tests on glass waste forms have been carried out. The examinations of alpha damage acceleration for the Synroc waste forms have also been performed. (author)

A spectrophotometric study of cerium IV and chromium VI species in nuclear fuel reprocessing process streams

International Nuclear Information System (INIS)

Nickson, I D; Boxall, C; Jackson, A; Whillock, G O H

2010-01-01

Nuclear fuel reprocessing schemes such as PUREX and UREX utilise HNO 3 media. An understanding of the corrosion of process engineering materials such as stainless steel in such media is a major concern for the nuclear industry. Two key species are cerium and chromium which, as Ce(IV), Cr(VI), may act as corrosion accelerants. An on-line analytical technique for these quantities would be useful for determining the relationship between corrosion rate and [Ce(IV)] and [Cr(VI)]. Consequently, a strategy for simultaneous quantification of Ce(IV), Cr(VI) and Cr(III) in the presence of other ions found in average burn-up Magnox / PWR fuel reprocessing stream (Fe, Mg, Nd, Al) is being developed. This involves simultaneous UV-vis absorbance measurement at 620, 540, 450 nm, wavelengths where Ce and Cr absorb but other ions do not. Mixed solutions of Cr(VI) and Ce(IV) are found to present higher absorbance values at 540 nm than those predicted from absorbances recorded from single component solutions of those ions. This is attributed to the formation of a 3:1 Cr(VI)-Ce(IV) complex and we report on the complexation and UV-visible spectrophotometric characteristics of this species. To the best of our knowledge this is the first experimental study of this complex in aqueous nitric acid solution systems.

Behavior of spent nuclear fuel and storage-system components in dry interim storage

International Nuclear Information System (INIS)

Johnson, A.B. Jr.; Gilbert, E.R.; Guenther, R.J.

1982-08-01

Irradiated nuclear fuel has been handled under dry conditions since the early days of nuclear reactor operation, and use of dry storage facilities for extended management of irradiated fuel began in 1964. Irradiated fuel is currently being stored dry in four types of facilities: dry wells, vaults, silos, and metal casks. Essentially all types of irradiated nuclear fuel are currently stored under dry conditions. Gas-cooled reactor (GCR) and liquid metal fast breeder reactor (LMFBR) fuels are stored in vaults and dry wells. Certain types of fuel are being stored in licensed dry storage facilities: Magnox fuel in vaults in the United Kingdom and organic-cooled reactor (OCR) fuel in silos in Canada. Dry storage demonstrations are under way for Zircaloy-clad fuel from boiling water reactors BWR's, pressurized heavy-water reactors (PHWRs), and pressurized water reactors (PWRs) in all four types of dry storage facilities. The demonstrations and related hot cell and laboratory tests are directed toward expanding the data base and establishing a licensing basis for dry storage of water reactor fuel. This report reviews the scope of dry interim storage technology, the performance of fuel and facility materials, the status of programs in several countries to license dry storage of water reactor fuel, and the characteristics of water reactor fuel that relate to dry storage conditions

Corrosion inhibition studies in support of the long term storage of AGR fuel

Energy Technology Data Exchange (ETDEWEB)

Standring, P [Sellafield Limited (United Kingdom)

2012-07-01

Thorp Receipt and Storage (at Sellafield, UK) is currently being investigated as a bridging solution for the storage of AGR fuel pending the out-come of a national review into spent fuel management. AGR spent fuel is known to be susceptible to corrosion through inter-granular attack. To avoid this, the chosen storage regime for AGR fuel is sodium hydroxide dosed pond water to pH 11.4; now 22 years of operating experience. The conversion of TR and S will require a phased transition. During this transition sodium hydroxide cannot be used due to materials compatibility issues. Alternative corrosion inhibitors have been investigated as an interim measure and sodium nitrate has been selected as a suitable candidate. The efficiency of sodium nitrate to inhibit propagating inter-granular attack of active AGR materials has yet to be established. In the longer term sodium hydroxide will be deployed along with a move to a closed loop pond water management system. Given that carbon dioxide is known to be absorbed by sodium hydroxide dosed water and can affect fuel integrity, in the case of Magnox fuel, there is a need to establish its impact on AGR fuel. The objectives are: To establish the impact of carbonate on AGR fuel corrosion; To establish the efficiency of sodium nitrate to inhibit propagating inter-granular attack of irradiated AGR materials.

Wylfa grabs the headlines

International Nuclear Information System (INIS)

Bindon, J.

1995-01-01

During normal refuelling operations on load at the Wylfa Magnox reactor in the United Kingdom on 31st July 1993, it was observed by an operator that part of the refuelling machine mechanism, the parasol grab weight, had become detached and had fallen into the reactor. The reactor conditions remained stable and no immediate operating changes were deemed necessary while immediate action was taken to locate the weight and evaluate the situation. However, after nearly nine hours fruitless search a controlled shut down of the reactor was undertaken in order to carry out inspection and recovery operations. The weight was finally recovered using specially constructed robotic equipment on 5th September 1993 and the reactor returned to power on 12th October. A welding failure was found to account for the detachment of the weight. During the depressurisation of the reactor pressure vessel to effect the recovery, the station's authorised weekly discharge of S35 was exceeded. This report examines the case brought by the Nuclear Installations Inspectorate against Nuclear Electric, the utility responsible for the reactor, and claims that the use of emotive language and misrepresentation of facts by the prosecuting counsel exaggerated the safety implications of the incident. Nuclear Electric, however, pleaded guilty to the basic case against the utility over an incident rated at level 2 on the International Nuclear Event Scale and was fined 1 250,000 with costs. (UK)

Simulation of Self-Irradiation of High-Sodium Content Nuclear Waste Glasses

International Nuclear Information System (INIS)

Pankov, Alexey S.; Ojovan, Michael I.; Batyukhnova, Olga G.; Lee, William E.

2007-01-01

Alkali-borosilicate glasses are widely used in nuclear industry as a matrix for immobilisation of hazardous radioactive wastes. Durability or corrosion resistance of these glasses is one of key parameters in waste storage and disposal safety. It is influenced by many factors such as composition of glass and surrounding media, temperature, time and so on. As these glasses contain radioactive elements most of their properties including corrosion resistance are also impacted by self-irradiation. The effect of external gamma-irradiation on the short-term (up to 27 days) dissolution of waste borosilicate glasses at moderate temperatures (30 deg. to 60 deg. C) was studied. The glasses studied were Magnox Waste glass used for immobilisation of HLW in UK, and K-26 glass used in Russia for ILW immobilisation. Glass samples were irradiated under γ-source (Co-60) up to doses 1 and 11 MGy. Normalised rates of elemental release and activation energy of release were measured for Na, Li, Ca, Mg, B, Si and Mo before and after irradiation. Irradiation up to 1 MGy results in increase of leaching rate of almost all elements from both MW and K-26 with the exception of Na release from MW glass. Further irradiation up to a dose of 11 MGy leads to the decrease of elemental release rates to nearly initial value. Another effect of irradiation is increase of activation energies of elemental release. (authors)

The economics of amine usage

International Nuclear Information System (INIS)

Fountain, M.J.

1994-01-01

Research carried out over the past decade in the USA (funded by EPRI) and by the CEGB/Nuclear Electric in the UK has identified several thermally stable, low-toxicity 'advanced' amines with good high-temperature basicity and low steam-water distribution ratio. As a direct result of this work several US PWR stations are now evaluating monoethanolamine (ETA) and Nuclear Electric's Wylfa Power Station (magnox) now doses 5 aminopentanol (5AP) instead of AMP, which had successfully combated erosion-corrosion for the past nine years. It has recently been stated that the use of 5AP ''...could save Nuclear Electric up to 1.5M pounds per year''. To provide US power station chemists with a tool for tailoring amine dosage to their own plant requirements EPRI has developed a computer model, Aminmod, which can, with user-defined circuit parameters and amine feed concentrations, calculate amine concentrations and pH(t) values at various points around the circuit. To complement this model a user-friendly spreadsheet program is being developed which will work in conjunction with Aminmod, via active links, to calculate the total operating cost associated with the selected amine dosing regime and compare alternative scenarios. This paper discusses the relationship between the technical and economic aspects of choosing an amine dosing regime and draws on combined Aminmod/spreadsheet results to illustrate how differences in amine properties can influence the optimum economic solution for a typical PWR. (author). 3 figs., 2 tabs., 5 refs

How much plutonium does North Korea really have?

International Nuclear Information System (INIS)

Dreicer, J.S.

1997-01-01

In a previous study, as part of the Global Nuclear Material Control Model effort, the author estimated the maximum quantity of plutonium that could be produced in thermal research reactors in the potential nuclear weapon states (including North Korea), based on their declared power level. D. Albright has estimated the amount of plutonium the North Koreans may have produced since 1986 in the 5-megawatt-electric power reactor at Yongbon. Albright provided an upper-bound estimate of 53 kilograms of weapon-grade plutonium produced cumulatively if the gas-graphite (magnox) reactor had achieved a load factor of 0.80. This cumulative estimate of 53 kilograms ignores the potential plutonium production in the 8-megawatt-thermal research reactor, IRT-DPRK. To better quantify the cumulative North Korean production, the author conducted a study to estimate the amount of plutonium that could have been produced in the IRT-DPRK research reactor operating at the declared power level during the entire period it has operated, including a period it was not safeguarded. The author estimates that, at most, an additional 6 to 33 kilograms of plutonium could have been produced cumulatively in the research reactor operating at the declared power level during the entire period it has operated, including a 12-year period it was not safeguarded, resulting in a total of 13 to 47 kilograms of plutonium possibly produced in both the research and power reactors

Annual report and accounts 1990/91

International Nuclear Information System (INIS)

1991-01-01

Scottish Nuclear Limited is Scotland's nuclear power generating company. It supplies a substantial proportion of Scotland's electricity requirement. Vested with its assets on 31 March 1990, the company is owned by the Secretary of State for Scotland and supplies all of its electricity to ScottishPower (74.9%) and Scottish Hydro-Electric (25.1%). The company owns and operates the Advanced Gas-cooled Reactor (AGR) nuclear power stations at Hunterston on the Firth of Clyde and at Torness on the east coast of Scotland. It is also responsible for the decommissioning of the Magnox nuclear power station, Hunterston 'A'. This was Scotland's first commercial nuclear power station and closed, after 26 years of successful electricity generation, on 30 March 1990. Scottish Nuclear's first year of operation as a separate entity has been both eventful and successful. In one short year we have demonstrated a determination to challenge established thinking and prove that nuclear generation can be both safe and economic. At Hunterston'B', Reactor 3 passed the milestone of 50,000 GWR generated, the first AGR to achieve this record. Torness continued to operate well and made progress towards the final commissioning of the fuel handling plant. Initiatives have been promoted in Eastern Europe. Closer to home the relative merits of reprocessing spent fuel and other means of disposal are being examined. The financial result for the year was a net loss of Pound 32.5 million which represents a major improvement on the Pound 189.9 million loss reported last year. (author)

Privatisation of the UK's nuclear power industry: nuclear's triple challenge

International Nuclear Information System (INIS)

Fraser, W.R.I.

1997-01-01

At the British Nuclear Congress in December 1996, Lord Fraser of Caryllie, then UK energy minister, set out the three key issues the nuclear industry must tackle for a successful future: (1) increased competition from other energy sources, (2) a growing world market for its skills and (3) a continuing tough regulatory regime. Nuclear power, with electricity generated in the UK rising to 25%, has responded well to competition from other energy sources, and also to the further competition generated by privatisation which has already generated benefits for the public. As other countries with nuclear programmes diversify and upgrade their technology this will create new export opportunities for Britain over and above those already in existence, notably by BNFL in Japan. Other areas that Britain has to offer relate to safety improvements, notably in eastern Europe, and decommissioning, in which Magnox Electric is one of the few operators in the world with experience in decommissioning a full scale commercial reactor. The regulatory framework for the nuclear industry will continue to be as rigorous as ever, but, however the industry is structured, it should be noted that commercial success and continued safe operations are inextricably linked. The industry must operate within the framework of the development of international treaties and agreements in the nuclear field. The Government will continue to take a close interest in the safety, security and prosperity of the nuclear industry, and help Britain as a whole to be a successful and influential player in the international nuclear community. (UK)

The measurement of moisture in nuclear coolant gases. Experience and new developments within the CEGB

International Nuclear Information System (INIS)

Hiorns, D.S.; Stallard, M.D.

1982-06-01

Humidity measurements on nuclear reactor coolant gases are required for many reasons, for instance to detect and locate water leakages from the boilers and to monitor the chemical composition of the coolant for normal operation and during commissioning and maintenance, and the assessment of the performance of driers. For leak detection sensitivity and rapid response are important whereas for routine monitoring drift may be a prime criterion. Some coolants include methane for chemical control that decomposes to water so the levels of moisture that normally exist in the coolant vary with reactor types. No one measurement technique or hygrometer system currently available can be expected to meet all these requirements and in the CEGB it has proved necessary to concentrate on finding a solution to each separately. This paper reviews CEGB experience with numerous hygrometer systems that have been used on both Magnox and AGR coolant gases and highlights some of the problems that have arisen. New development work in the important and demanding area of boiler leak detection and location is also included where a number of new approaches are being investigated, including:- (i) An improved 'first-up' system based on coulometric moisture analysers. (ii) A differential system based on the piezo-electric hygrometer. (iii) A microprocessor controlled system using capacitance probes. Whilst work on the development of new instruments and the design of approved systems is proceeding at different locations within the CEGB it is being reported, together with the latest operational experiences, through the CEGB Chemical Measuring Instruments Advisory Group, on whose behalf this paper is presented. (author)

Thermal oxidation of nuclear graphite: A large scale waste treatment option

Science.gov (United States)

Jones, Abbie N.; Marsden, Barry J.

2017-01-01

This study has investigated the laboratory scale thermal oxidation of nuclear graphite, as a proof-of-concept for the treatment and decommissioning of reactor cores on a larger industrial scale. If showed to be effective, this technology could have promising international significance with a considerable impact on the nuclear waste management problem currently facing many countries worldwide. The use of thermal treatment of such graphite waste is seen as advantageous since it will decouple the need for an operational Geological Disposal Facility (GDF). Particulate samples of Magnox Reactor Pile Grade-A (PGA) graphite, were oxidised in both air and 60% O2, over the temperature range 400–1200°C. Oxidation rates were found to increase with temperature, with a particular rise between 700–800°C, suggesting a change in oxidation mechanism. A second increase in oxidation rate was observed between 1000–1200°C and was found to correspond to a large increase in the CO/CO2 ratio, as confirmed through gas analysis. Increasing the oxidant flow rate gave a linear increase in oxidation rate, up to a certain point, and maximum rates of 23.3 and 69.6 mg / min for air and 60% O2 respectively were achieved at a flow of 250 ml / min and temperature of 1000°C. These promising results show that large-scale thermal treatment could be a potential option for the decommissioning of graphite cores, although the design of the plant would need careful consideration in order to achieve optimum efficiency and throughput. PMID:28793326

Thermal oxidation of nuclear graphite: A large scale waste treatment option.

Directory of Open Access Journals (Sweden)

Alex Theodosiou

Full Text Available This study has investigated the laboratory scale thermal oxidation of nuclear graphite, as a proof-of-concept for the treatment and decommissioning of reactor cores on a larger industrial scale. If showed to be effective, this technology could have promising international significance with a considerable impact on the nuclear waste management problem currently facing many countries worldwide. The use of thermal treatment of such graphite waste is seen as advantageous since it will decouple the need for an operational Geological Disposal Facility (GDF. Particulate samples of Magnox Reactor Pile Grade-A (PGA graphite, were oxidised in both air and 60% O2, over the temperature range 400-1200°C. Oxidation rates were found to increase with temperature, with a particular rise between 700-800°C, suggesting a change in oxidation mechanism. A second increase in oxidation rate was observed between 1000-1200°C and was found to correspond to a large increase in the CO/CO2 ratio, as confirmed through gas analysis. Increasing the oxidant flow rate gave a linear increase in oxidation rate, up to a certain point, and maximum rates of 23.3 and 69.6 mg / min for air and 60% O2 respectively were achieved at a flow of 250 ml / min and temperature of 1000°C. These promising results show that large-scale thermal treatment could be a potential option for the decommissioning of graphite cores, although the design of the plant would need careful consideration in order to achieve optimum efficiency and throughput.

Corrosion of inconel in high-temperature borosilicate glass melts containing simulant nuclear waste

Science.gov (United States)

Mao, Xianhe; Yuan, Xiaoning; Brigden, Clive T.; Tao, Jun; Hyatt, Neil C.; Miekina, Michal

2017-10-01

The corrosion behaviors of Inconel 601 in the borosilicate glass (MW glass) containing 25 wt.% of simulant Magnox waste, and in ZnO, Mn2O3 and Fe2O3 modified Mg/Ca borosilicate glasses (MZMF and CZMF glasses) containing 15 wt.% of simulant POCO waste, were evaluated by dimensional changes, the formation of internal defects and changes in alloy composition near corrosion surfaces. In all three kinds of glass melts, Cr at the inconel surface forms a protective Cr2O3 scale between the metal surface and the glass, and alumina precipitates penetrate from the metal surface or formed in-situ. The corrosion depths of inconel 601 in MW waste glass melt are greater than those in the other two glass melts. In MW glass, the Cr2O3 layer between inconel and glass is fragmented because of the reaction between MgO and Cr2O3, which forms the crystal phase MgCr2O4. In MZMF and CZMF waste glasses the layers are continuous and a thin (Zn, Fe, Ni, B)-containing layer forms on the surface of the chromium oxide layer and prevents Cr2O3 from reacting with MgO or other constituents. MgCr2O4 was observed in the XRD analysis of the bulk MW waste glass after the corrosion test, and ZrSiO4 in the MZMF waste glass, and ZrSiO4 and CaMoO4 in the CZMF waste glass.

Safety against releases in severe accidents. Final report

International Nuclear Information System (INIS)

Lindholm, I.; Berg, Oe.; Nonboel, E.

1997-12-01

The work scope of the RAK-2 project has involved research on quantification of the effects of selected severe accident phenomena for Nordic nuclear power plants, development and testing of a computerised accident management support system and data collection and description of various mobile reactors and of different reactor types existing in the UK. The investigations of severe accident phenomena focused mainly on in-vessel melt progression, covering a numerical assessment of coolability of a degraded BWR core, the possibility and consequences of a BWR reactor to become critical during reflooding and the core melt behavior in the reactor vessel lower plenum. Simulant experiments were carried out to investigate lower head hole ablation induced by debris discharge. In addition to the in-vessel phenomena, a limited study on containment response to high pressure melt ejection in a BWR and a comparative study on fission product source term behaviour in a Swedish PWR were performed. An existing computerised accident management support system (CAMS) was further developed in the area of tracking and predictive simulation, signal validation, state identification and user interface. The first version of a probabilistic safety analysis module was developed and implemented in the system. CAMS was tested in practice with Barsebaeck data in a safety exercise with the Swedish nuclear authority. The descriptions of the key features of British reactor types, AGR, Magnox, FBR and PWR were published as data reports. Separate reports were issued also on accidents in nuclear ships and on description of key features of satellite reactors. The collected data were implemented in a common Nordic database. (au)

Safety against releases in severe accidents. Annual report 1996. Project plan 1997

International Nuclear Information System (INIS)

1997-01-01

The work scope of the RAK-2 project is divided into three sub-projects: RAK-2.1 Severe Accident Phenomenology; RAK-2.2 Computerised Accident Management; RAK-2.3 Reactors In Nordic Surroundings. The work in subproject 1 progresses roughly according to budget and time schedule. Some adjustments in the technical work scope were made during 1996. Main tasks of RAK-2.1 in 1996: Complete recriticality studies for Nordic BWRs; Investigate phenomena related to late phase melt progression; Issue and NKS Final Technical Report on KTH experiments. Main tasks of RAK-2.2 in 1996: CAMS would be further developed with signal validation, tracking simulation, state identification and PSA and risk monitoring applications; Carry out a feasibility study for development of a PWR version of CAMS in collaboration with EdF, France; Use CAMS in the Halden Man-Machine laboratory to perform human factor studies. Main tasks of RAK-2.3 in 1996: Collect and report data from the British reactor types AGR, MAGNOX and PWR; Make a report on accidents in nuclear ships; Put the collected data together in a common data base covering neighbour reactors treated in SIK-3 and RAK-2.3; Update the data in the former SIK-3 report if needed. The work in project 2 progresses according to plans. The data collection of British reactors with in sub-project 3 has been delayed significantly due to difficulty of obtaining information from some of the British utilities, but the problems are expected to be solved by the end of 1997. (EG)

Safety against releases in severe accidents. Annual report 1996. Project plan 1997; Saekerhet mot utslaepp vid reaktorhaverier. Aarsrapport 1996. Plans 1997

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-01-01

The work scope of the RAK-2 project is divided into three sub-projects: RAK-2.1 Severe Accident Phenomenology; RAK-2.2 Computerised Accident Management; RAK-2.3 Reactors In Nordic Surroundings. The work in subproject 1 progresses roughly according to budget and time schedule. Some adjustments in the technical work scope were made during 1996. Main tasks of RAK-2.1 in 1996: Complete recriticality studies for Nordic BWRs; Investigate phenomena related to late phase melt progression; Issue and NKS Final Technical Report on KTH experiments. Main tasks of RAK-2.2 in 1996: CAMS would be further developed with signal validation, tracking simulation, state identification and PSA and risk monitoring applications; Carry out a feasibility study for development of a PWR version of CAMS in collaboration with EdF, France; Use CAMS in the Halden Man-Machine laboratory to perform human factor studies. Main tasks of RAK-2.3 in 1996: Collect and report data from the British reactor types AGR, MAGNOX and PWR; Make a report on accidents in nuclear ships; Put the collected data together in a common data base covering neighbour reactors treated in SIK-3 and RAK-2.3; Update the data in the former SIK-3 report if needed. The work in project 2 progresses according to plans. The data collection of British reactors with in sub-project 3 has been delayed significantly due to difficulty of obtaining information from some of the British utilities, but the problems are expected to be solved by the end of 1997. (EG).

Modular high-temperature gas-cooled reactor

International Nuclear Information System (INIS)

Shepherd, L.R.

1988-01-01

The high financial risk involved in building large nuclear power reactors has been a major factor in halting investment in new plant and in bringing further technical development to a standstill. Increased public concern about the safety of nuclear plant, particularly after Chernobyl, has contributed to this stagnation. Financial and technical risk could be reduced considerably by going to small modular units, which would make it possible to build up power station capacity in small steps. Such modular plant, based on the helium-cooled high temperature reactor (HTR), offers remarkable advantages in terms of inherent safety characteristics, partly because of the relatively small size of the individual modules but more on account of the enormous thermal capacity and high temperature margins of the graphitic reactor assemblies. Assessments indicate that, in the USA, the cost of power from the modular systems would be less than that from conventional single reactor plant, up to about 600 MW(e), and only marginally greater above that level, a margin that should be offset by the shorter time required in bringing the modular units on line to earn revenue. The modular HTR would be particularly appropriate in the UK, because of the considerable British industrial background in gas-cooled reactors, and could be a suitable replacement for Magnox. The modular reactor would be particularly suited to combined heat and power schemes and would offer great potential for the eventual development of gas turbine power conversion and the production of high-temperature process heat. (author)

Proceedings of the joint WANO/OECD-NEA workshop on pre-stress loss in NPP containments

International Nuclear Information System (INIS)

1997-01-01

This joint WANO/OECD-NEA workshop on pre-stress loss in NPP containments started with Opening Remarks (by OECD and EDF) and two presentations on 'Creep and Shrinkage of Concrete: Physical Origins, Practical Measurements', and 'Past, Present and Future Techniques for Predicting Creep and Shrinkage of Concrete'. It was then followed by papers and presentations from 12 countries, which titles are: Assessment of Creep Methodologies for Predicting Prestressing Forces Losses in Nuclear Power Plant Containments; Prestress Behaviour in Belgian NPP Containments; Presentation of Gentilly 2 NPP Containment (abstract only); Containment Structure Monitoring and Prestress Losses; Experience from Daya Bay Nuclear Power Plant (China); Prestress losses in NPP containments - the EDF experience; Prestress Force Monitoring on the THTR Prestressed Concrete Reactor Vessel During 19 Years; NPP Containment Design: Evolution and Indian Experience; In-Service Inspections and R and D of PCCVs in Japan; Comparison of Grouted and Un-grouted Tendons in NPP Containments; Prestress Losses in Containment of VVER 1000 Units; Prestressing in Nuclear Power Plants; Anchor Lift-off Measuring System for 37 T 15 Tendons; Monitoring of Stressed-Strained State and Forces in Reinforcing Cables of Prestressed Containment Shells of Nuclear Power Plants; Long-Term In-Service Monitoring of Pre-stressing in Magnox Pre-stressed Concrete Pressure Vessels; The Measurement of Un-bonded Tendon Loads in PCPV and Primary Containment Buildings; The Long Term In-service Performance of Corrosion Protection to Prestressing Tendons in AGR Prestressed Concrete Pressure Vessels; Prestress Force Losses in Containments of U.S. Nuclear Power Plants. Discussions and a synthesis are also presented

Nuclear Legislation in OECD and NEA Countries. Regulatory and Institutional Framework for Nuclear Activities - United Kingdom

International Nuclear Information System (INIS)

2003-01-01

This country profile provide comprehensive information on the regulatory and Institutional Framework governing nuclear activities as well as a detailed review of a full range of nuclear law topics, including: mining regime; radioactive substances; nuclear installations; trade in nuclear materials and equipment; radiation protection; radioactive waste management; non-proliferation and physical protection; transport; and nuclear third party liability. The profile is complemented by reproductions of the primary legislation regulating nuclear activities in the country. Content: I. General Regulatory Regime: 1. Introduction; 2. Mining Regime; 3. Radioactive Substances; 4. Nuclear Installations (Licensing and inspection, including nuclear safety; Protection of the environment against radiation effects; Emergency response); 5. Trade in Nuclear Materials and Equipment; 6. Radiation Protection; 7. Radioactive Waste Management; 8. Non-Proliferation and Physical Protection; 9. Transport; 10. Nuclear Third Party Liability; II. Institutional Framework: 1. Regulatory and Supervisory Authorities (Department of Trade and Industry - DTI; Secretary of State for Environment, Food and Rural Affairs and the Secretary of State for Health; Secretary of State for Transport; Secretary of State for Education); 2. Advisory Bodies (Medical Research Council - MRC; Nuclear Safety Advisory Committee; Radioactive Waste Management Advisory Committee); 3. Public and Semi-Public Agencies (United Kingdom Atomic Energy Authority - UKAEA; Health and Safety Commission and Executive - HSC/HSE; National Radiological Protection Board - NRPB; Environment Agencies; British Nuclear Fuels plc. - BNFL; Amersham International plc.; The National Nuclear Corporation Ltd. - NNC; United Kingdom Nirex Ltd.; Magnox Electric plc.; British Energy Generation Ltd.; Scottish Electricity Generator Companies; British Energy Generation Ltd.; Regional Electricity Companies in England and Wales)

Examination of Surface Deposits on Oldbury Reactor Core Graphite to Determine the Concentration and Distribution of 14C.

Directory of Open Access Journals (Sweden)

Liam Payne

Full Text Available Pile Grade A graphite was used as a moderator and reflector material in the first generation of UK Magnox nuclear power reactors. As all of these reactors are now shut down there is a need to examine the concentration and distribution of long lived radioisotopes, such as 14C, to aid in understanding their behaviour in a geological disposal facility. A selection of irradiated graphite samples from Oldbury reactor one were examined where it was observed that Raman spectroscopy can distinguish between underlying graphite and a surface deposit found on exposed channel wall surfaces. The concentration of 14C in this deposit was examined by sequentially oxidising the graphite samples in air at low temperatures (450°C and 600°C to remove the deposit and then the underlying graphite. The gases produced were captured in a series of bubbler solutions that were analysed using liquid scintillation counting. It was observed that the surface deposit was relatively enriched with 14C, with samples originating lower in the reactor exhibiting a higher concentration of 14C. Oxidation at 600°C showed that the remaining graphite material consisted of two fractions of 14C, a surface associated fraction and a graphite lattice associated fraction. The results presented correlate well with previous studies on irradiated graphite that suggest there are up to three fractions of 14C; a readily releasable fraction (corresponding to that removed by oxidation at 450°C in this study, a slowly releasable fraction (removed early at 600°C in this study, and an unreleasable fraction (removed later at 600°C in this study.

Safety against releases in severe accidents. Final report

Energy Technology Data Exchange (ETDEWEB)

Lindholm, I.; Berg, Oe.; Nonboel, E. [eds.

1997-12-01

The work scope of the RAK-2 project has involved research on quantification of the effects of selected severe accident phenomena for Nordic nuclear power plants, development and testing of a computerised accident management support system and data collection and description of various mobile reactors and of different reactor types existing in the UK. The investigations of severe accident phenomena focused mainly on in-vessel melt progression, covering a numerical assessment of coolability of a degraded BWR core, the possibility and consequences of a BWR reactor to become critical during reflooding and the core melt behavior in the reactor vessel lower plenum. Simulant experiments were carried out to investigate lower head hole ablation induced by debris discharge. In addition to the in-vessel phenomena, a limited study on containment response to high pressure melt ejection in a BWR and a comparative study on fission product source term behaviour in a Swedish PWR were performed. An existing computerised accident management support system (CAMS) was further developed in the area of tracking and predictive simulation, signal validation, state identification and user interface. The first version of a probabilistic safety analysis module was developed and implemented in the system. CAMS was tested in practice with Barsebaeck data in a safety exercise with the Swedish nuclear authority. The descriptions of the key features of British reactor types, AGR, Magnox, FBR and PWR were published as data reports. Separate reports were issued also on accidents in nuclear ships and on description of key features of satellite reactors. The collected data were implemented in a common Nordic database. (au) 39 refs.

The power of British Energy

International Nuclear Information System (INIS)

Hawley, R.

1997-01-01

When the power industry in Britain was privatized, British Energy plc (BE), whose head office is in Edingburgh, Scotland, was founded in July 1996. It is the only power utility in the world exclusively operating nuclear power stations. Operative business has remained the responsibility of the two regional supply companies, Nuclear Electric (NE) and Scottish Nuclear (SN) which, in addition to the modern PWR nuclear generating unit of Sizewell B, have included in the new holding company their advanced gas-cooled and gas-moderated reactor (AGR) units. The older gas-graphite reactor (GGR) plants were combined in the new Magnox Electric plc, Berkeley; at some later date, this company is to be merged with another nuclear power plant operator, British Nuclear Fuels plc (BNFL). Sizewell B, which was commissioned in 1995, is the last nuclear generating unit to be started up in the United Kingdom, for the time being. In times of low raw material prices and the need for a quick return on invested capital, BE is reluctant to run the risk associated with tying up capital for a long time. Instead, the company has backfitted its plants so that the production of electricity from nuclear power in Britain in 1996 of 92,476 GWh was increased by almost 10% over the 1995 level of 84,174 GWh. In addition to modernization and rationalization at home, BE together with Sizewell B vendor Westinghouse is engaged worldwide in the development and commercialization of future advanced reactors. This ensures that the know-how accumulated will be preserved and will be available for new nuclear power plants to be built in Britain in the next century. (orig.)

Gas Generation in Radioactive Wastes - MAGGAS Predictive Life Cycle Model

International Nuclear Information System (INIS)

Streatfield, R.E.; Hebditch, D.J.; Swift, B.T.; Hoch, A.R.; Constable, M.

2006-01-01

Gases may form from radioactive waste in quantities posing different potential hazards throughout the waste package life cycle. The latter includes surface storage, transport, placing in an operating repository, storage in the repository prior to backfill, closure and the post-closure stage. Potentially hazardous situations involving gas include fire, flood, dropped packages, blocked package vents and disruption to a sealed repository. The MAGGAS (Magnox Gas generation) model was developed to assess gas formation for safety assessments during all stages of the waste package life cycle. This is a requirement of the U.K. regulatory authorities and Nirex and progress in this context is discussed. The processes represented in the model include: Corrosion, microbial degradation, radiolysis, solid-state diffusion, chemico-physical degradation and pressurisation. The calculation was split into three time periods. First the 'aerobic phase' is used to model the periods of surface storage, transport and repository operations including storage in the repository prior to backfill. The second and third periods were designated 'anaerobic phase 1' and 'anaerobic phase 2' and used to model the waste packages in the post-closure phase of the repository. The various significant gas production processes are modeled in each phase. MAGGAS (currently Version 8) is mounted on an Excel spreadsheet for ease of use and speed, has 22 worksheets and is operated routinely for assessing waste packages (e.g. for ventilation of stores and pressurisation of containers). Ten operational and decommissioning generic nuclear power station waste streams were defined as initial inputs, which included ion exchange materials, sludges and concentrates, fuel element debris, graphite debris, activated components, contaminated items, desiccants and catalysts. (authors)

Safeguards By Design - As applied to the Sellafield Product and Residue Store (SPRS)

Energy Technology Data Exchange (ETDEWEB)

Chare, Peter; Lahogue, Yves; Schwalbach, Peter; Smejkal, Andreas; Patel, Bharat [European Commission, Directorate-General for Energy, Directorate E - Nuclear Safeguards, Euroforum, Luxembourg (Luxembourg)

2011-12-15

Sellafield Product and Residue Store (SPRS) is a new facility that has been constructed on the site of Sellafield. The design work started in early 2001 and active commissioning commenced with the introduction of the first nuclear material which arrived in the building early 2011. The store has been designed for the long term storage of Plutonium product (PuO2) from Thorp and Magnox, MOX residue powder from Sellafield MOX Plant (SMP) as well as pellet, powder or granular PuO2 residues from the older stores on the Sellafield site. This paper describes the application of Safeguards By Design commencing at the early design stage based upon the Safeguards Approach to be applied by DG ENER at the Sellafield Product and Residue Store (SPRS). The approach had been developed based upon the requirements for implementing Commission Regulation 302(2005) and the technical measures to be implemented in order to meet Article 77(a) of the Euratom Treaty. In order to meet these requirements a close dialogue was established between the different interested parties and the design team for the installation of instrumentation with associated cabling in order to implement the agreed safeguards measures. Early contacts at the design stage facilitated the inclusion of installed safeguards supplied instrumentation into the overall design and facility construction. The equipment and cabling supplied by Euratom was incorporated into the planning and construction phases. This ensured that upon plant completion the safeguards tools were commissioned and ready for the verification of the first nuclear material to be introduced into SPRS. Detailed discussions at the early stages of the design phase raised the profile of nuclear material safeguards and made certain that the necessary instrumentation infrastructure was incorporated into the plant infrastructure.

Conditioning for definitive storage of radioactive graphite bricks from reactor decommissioning

International Nuclear Information System (INIS)

Costes, J.R.; Koch, C.; Tassigny, C. de; Vidal, H.; Raymond, A.

1990-01-01

The decommissioning of gas-graphite reactors in the EC (e.g. French UNGGs, British Magnox reactors and AGRs, and reactors in Spain and in Italy) will produce large amounts of graphite bricks. This graphite cannot be accepted without particular conditioning by the existing shallow land disposal sites. The aim of the study is to examine the behaviour of graphite waste and to develop a conditioning technique which makes this waste acceptable for shallow land disposal sites. 18 kg of graphite core samples with an outside diameter of 74 mm were removed from the G2 gas-cooled reactor at Marcoule. Their radioactivity is highly dependent on the position of the graphite bricks inside the reactor. Measured results indicate an activity range of 100-400 MBq/kg with 90% Tritium, 5% 14 C, 3% 60 Co, 1.5% 63 Ni. Repeated porosity analyses showed that open porosity ranging from 0 to 100 μm exceeded 23 vol% in the graphite. Water penetration kinetics were investigated in unimpregnated graphite and resulted in impregnation by water of 50-90% of the open porosity. Preliminary lixiviation tests on the crude samples showed quick lixidegree of Cs (several per cent) and of 60 Co, and 133 Ba at a lesser degree. The proposed conditioning technique does not involve a simple coating but true impregnation by a tar-epoxy mixture. The bricks recovered intact from the core by robot services will be placed one by one inside a cylindrical metallic container. But this container may corrode and the bricks may become fragmented in the future, the normally porous graphite will be unaffected by leaching since it is proved that all pores larger than 0.1 μm will be filled with the tar-epoxy mixture. This is a true long-term waste packaging concept. The very simple technology required for industrial implementation is discussed

Impact of radiolysis and radiolytic corrosion on the release of {sup 13}C and {sup 37}Cl implanted into nuclear graphite: Consequences for the behaviour of {sup 14}C and {sup 36}Cl in gas cooled graphite moderated reactors

Energy Technology Data Exchange (ETDEWEB)

Moncoffre, N., E-mail: nathalie.moncoffre@ipnl.in2p3.fr [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Toulhoat, N. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); CEA/DEN, Centre de Saclay (France); Bérerd, N.; Pipon, Y. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Université de Lyon, Université Lyon, IUT Lyon-1 département chimie (France); Silbermann, G. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); EDF – DPI - DIN – CIDEN, DIE - Division Environnement, Lyon (France); Blondel, A. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); Andra, Châtenay-Malabry (France); Galy, N. [Université de Lyon, Université Lyon 1, CNRS/IN2P3, UMR5822, Institut de Physique Nucléaire de Lyon (IPNL) (France); EDF – DPI - DIN – CIDEN, DIE - Division Environnement, Lyon (France); and others

2016-04-15

Graphite finds widespread use in many areas of nuclear technology based on its excellent moderator and reflector qualities as well as its strength and high temperature stability. Thus, it has been used as moderator or reflector in CO{sub 2} cooled nuclear reactors such as UNGG, MAGNOX, and AGR. However, neutron irradiation of graphite results in the production of {sup 14}C (dose determining radionuclide) and {sup 36}Cl (long lived radionuclide), these radionuclides being a key issue regarding the management of the irradiated waste. Whatever the management option (purification, storage, and geological disposal), a previous assessment of the radioactive inventory and the radionuclide's location and speciation has to be made. During reactor operation, the effects of radiolysis are likely to promote the radionuclide release especially at the gas/graphite interface. Radiolysis of the coolant is mainly initiated through γ irradiation as well as through Compton electrons in the graphite pores. Radiolysis can be simulated in laboratory using γ irradiation or ion irradiation. In this paper, {sup 13}C, {sup 37}Cl and {sup 14}N are implanted into virgin nuclear graphite in order to simulate respectively the presence of {sup 14}C, {sup 36}Cl and nitrogen, a {sup 14}C precursor. Different irradiation experiments were carried out using different irradiation devices on implanted graphite brought into contact with a gas simulating the coolant. The aim was to assess the effects of gas radiolysis and radiolytic corrosion induced by γ or He{sup 2+} irradiation at the gas/graphite interface in order to evaluate their role on the radionuclide release. Our results allow inferring that radiolytic corrosion has clearly promoted the release of {sup 14}C, {sup 36}Cl and {sup 14}N located at the graphite brick/gas interfaces and open pores.

Sub-aquatic response of a scintillator, fibre optic and silicon photomultiplier based radiation sensor

Energy Technology Data Exchange (ETDEWEB)

Jackson, Sarah F., E-mail: s.f.jackson@lancaster.ac.uk [Engineering Department, Lancaster University, Lancaster (United Kingdom); Monk, Stephen D., E-mail: s.monk@lancaster.ac.uk [Engineering Department, Lancaster University, Lancaster (United Kingdom); Stanley, Steven J., E-mail: steven.j.stanley@nnl.co.uk [National Nuclear Laboratory, A709 Springfields, Preston (United Kingdom); Lennox, Kathryn, E-mail: kathryn.lennox@nnl.co.uk [National Nuclear Laboratory, A709 Springfields, Preston (United Kingdom)

2014-07-01

We describe an attempt at the utilisation of two low level light sensors to improve on the design of a dose monitoring system, specifically for underwater applications with consideration for the effects of water attenuation. The gamma radiation ‘RadLine{sup ®}’ detector consists of an inorganic scintillating crystal coupled to a fibre optic cable which transports scintillation photons, up to hundreds of metres, to an optical sensor. Analysed here are two contemporary technologies; SensL's MiniSL a silicon photomultiplier (SiPM) and a Sens-Tech photon counting photomultiplier tube (PMT). A clinical radiotherapy linear accelerator (linac) is implemented as test beam, subjecting the RadLine{sup ®} to a highly controlled dose rate (ranging from 0 Sv h{sup −1} to 320 Sv h{sup −1}), averaging at 2 MeV in energy. The RadLine's underwater dose monitoring capabilities are tested with the aid of epoxy resin ‘solid water’ phantom blocks, used as a substitute for water. Our results show that the MiniSL SiPM is unsuitable for this application due to extremely high background noise levels, however the Sens-Tech PMT performs satisfactorily and the detected dose rate due to the effects of water attenuation compares strongly with MCNP simulation data and NIST database values. We conclude that the PMT shows promise for its ultimate use in the First Generation Magnox Storage Pond (FGMSP) on the Sellafield site. - Highlights: • RadLine{sup ®} consists of a scintillating crystal coupled to a fibre optic cable and photon detector. • Here the dose monitoring system is trialled with SiPM and PMT type photon detectors. • A clinical linear accelerator (linac) is used as a test beam. • Sub-aquatic response is compared to Monte Carlo simulations and the NIST database.

SNAKES manipulator and ARD sluicer testing - April 1997

International Nuclear Information System (INIS)

Berglin, E.J.

1997-01-01

Long reach arms represent one of the options available for deployment of end effectors which can be used in the retrieval of radioactive waste, from the Hanford single shell tanks. The versatility of an arm based deployment system is such that it has the potential to improve the performance of a wide range of end effectors compared with stand-alone or other deployment methods. The long term reliability and availability of the deployment system is central to the timely completion of a waste retrieval program. However, concerns have been expressed over the dynamic performance of long reach arms and it is essential that an arm based system can cope with operational dynamic loads generated by end effectors. The test program conducted set out to measure static and dynamic loads and responses from a representative arm and sluicer, with the objective of extrapolating the data to a long reach arm system, that can be used for in-tank waste retrieval. As an arm with an appropriate reach was not available, the test program was undertaken to measure dynamic characteristics of a Magnox Electric 18 ft multi-link, hydraulically actuated SNAKES manipulator. This is the longest reach unit in service, albeit only one third of the 50 ft length required for in-tank waste retrieval. In addition operational performance and loading measurements were obtained from a low pressure confined system sluicer under development by ARD Environmental, to add to the end effector data base. When subject to impulse loading, the arm was found to behave in a repeatable manner having fundamental natural frequencies in the vertical and transverse directions of 1 Hz. There were also a large number of higher natural frequencies measured up to 100 Hz

Nuclear waste viewed in a new light; a synchrotron study of uranium encapsulated in grout

Energy Technology Data Exchange (ETDEWEB)

Stitt, C.A., E-mail: Camilla.stitt@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hart, M., E-mail: oxford.mike@gmail.com [Diamond Light Source Limited, Harwell Science and Innovation Campus, Fermi Avenue, Didcot, Oxfordshire OX11 0QX (United Kingdom); Harker, N.J., E-mail: nicholas.harker@esrf.fr [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Hallam, K.R., E-mail: k.r.hallam@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); MacFarlane, J., E-mail: james.macfarlane@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Banos, A., E-mail: antonis.banos@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Paraskevoulakos, C., E-mail: cp13846@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Butcher, E., E-mail: ed.j.butcher@nnl.co.uk [National Nuclear Laboratory, Seascale, Cumbria CA20 1 PG (United Kingdom); Padovani, C., E-mail: cristiano.padovani@nda.gov.uk [Radioactive Waste Management Limited (formerly the Radioactive Waste Management Directorate of the UK Nuclear Decommissioning Authority), Curie Avenue, Didcot, Oxfordshire OX11 0RH (United Kingdom); Scott, T.B., E-mail: t.b.scott@bristol.ac.uk [Interface Analysis Centre, H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)

2015-03-21

Highlights: • Unirradiated Magnox uranium was encapsulated in grout and exposed to hydrogen. • Synchrotron X-ray tomography imaged the uranium corrosion before and after exposure. • Synchrotron X-ray powder diffraction identified the corrosion products; UH{sub 3} and UO{sub 2}. • Uranium encapsulated in grout oxidised via the anoxic U + H{sub 2}O regime. • Successful in-situ, non-invasive examination of pyrophoric and radioactive material - Abstract: How do you characterise the contents of a sealed nuclear waste package without breaking it open? This question is important when the contained corrosion products are potentially reactive with air and radioactive. Synchrotron X-rays have been used to perform micro-scale in-situ observation and characterisation of uranium encapsulated in grout; a simulation for a typical intermediate level waste storage packet. X-ray tomography and X-ray powder diffraction generated both qualitative and quantitative data from a grout-encapsulated uranium sample before, and after, deliberately constrained H{sub 2} corrosion. Tomographic reconstructions provided a means of assessing the extent, rates and character of the corrosion reactions by comparing the relative densities between the materials and the volume of reaction products. The oxidation of uranium in grout was found to follow the anoxic U + H{sub 2}O oxidation regime, and the pore network within the grout was observed to influence the growth of uranium hydride sites across the metal surface. Powder diffraction analysis identified the corrosion products as UO{sub 2} and UH{sub 3}, and permitted measurement of corrosion-induced strain. Together, X-ray tomography and diffraction provide means of accurately determining the types and extent of uranium corrosion occurring, thereby offering a future tool for isolating and studying the reactions occurring in real full-scale waste package systems.

A study of the coefficient of thermal expansion of nuclear graphites

International Nuclear Information System (INIS)

Hacker, P.J.

2001-02-01

This thesis presents the results of a study of the Coefficient of Thermal Expansion (CTE) of two grades of nuclear graphite that are used as the moderator in the Magnox and Advanced Gas-Cooled reactors operated in the UK. This work has two main aims, the first is to characterise those elements of the graphite microstructure that control CTE within these materials and to relate these to the effects induced within the reactor. The second is to develop a microstructural model, of general applicability, that can initially be applied to model the CTE changes within the graphites under reactor conditions (neutron irradiation and radiolytic oxidation). These aims have been met by study in three interlinked areas, theoretical, experimental and modelling. Previous to this study, a loose assembly of single crystals together with changes in small scale nanometric porosity (Mrozowski cracks) were used to describe CTE behaviour of nuclear graphite both as-received and under reactor conditions. Within the experimental part of this thesis the graphite nanostructure was studied using, primarily, Transmission Electron Microscopy (TEM). This work concluded that structure on this scale was complex and that the loose assembly of single crystals was a poor microstructural approximation for modelling the CTE of these materials. Other experimental programmes measured the CTE of highly oxidised samples and simulated the effects of irradiation. The former discovered that CTE remained largely unaffected to high weight losses. This insensitivity was explained by ''The Continuous Network Hypothesis'' that was also related to classical percolation theory. The final part of the thesis modelled an abstraction of the key microstructural features identified in the previous parts of the thesis. This approach has been applied to AGR moderator graphite where it has successfully modelled the thermal expansion behaviour of the as-received, irradiated and oxidised material. (author)

Examination of long-stored uranium metal

International Nuclear Information System (INIS)

Gate, A.M.; Hambley, D.I.

2013-01-01

A small quantity of unirradiated uranium from Magnox fuel elements is currently held in archive storage. Some of these samples date back to the late fifties. This material has been stored, untreated, in unsealed containers in air at ambient temperature, humidity and pressure conditions. Such conditions are relevant to those that may exist in a passive storage facility. A sample of this material has been subject to optical, electron-optical and Raman spectroscopic examination to determine the extent of corrosion and the composition of corrosion product arising from long-term, low-temperature oxidation of uranium metal in air. The examinations have established that, even after a period in excess of 40 years, there was no observable spalling of uranium oxide from the sample during storage. The extent of oxidation of the metal, derived by SEM analysis, was slight and insignificant in relation to overall structural stability of the material. Raman spectroscopy data showed that the bulk of the oxide layer was comprised of hyper-stoichiometric UO 2 , with U 4 O 9 being the dominant component. The oxygen/uranium ratio was observed to be decreased at the metal/oxide interface, with a very thin layer that consisted of mainly UO 2 at the metal surface. At the oxide/air interface, a very thin U 3 O 8 layer was detected. U 4 O 9 is relatively mechanically stable, due to a significantly higher density than UO 2 and U 3 O 8 . It is likely that the lower internal stresses in the thick U 4 O 9 layer have resulted in less oxide film cracking than would be expected from UO 2 or U 3 O 8 and hence the low oxidation rate observed. These results suggest that storage of uranium metal in air over decades is a safe and credible option. (authors)

UK experience of safety requirements for thermal reactor stations

International Nuclear Information System (INIS)

Matthews, R.R.; Dale, G.C.; Tweedy, J.N.

1977-01-01

The paper summarises the development of safety requirements since the first of the Generating Boards' Magnox reactors commenced operation in 1962 and includes A.G.R. safety together with the preparation of S.G.H.W.R. design safety criteria. It outlines the basic principles originally adopted and shows how safety assessment is a continuing process throughout the life of a reactor. Some description is given of the continuous effort over the years to obtain increased safety margins for existing and new reactors, taking into account the construction and operating experience, experimental information, and more sophisticated computer-aided design techniques which have become available. The main safeguards against risks arising from the Generating Boards' reactors are the achievement of high standards of design, construction and operation, in conjunction with comprehensive fault analyses to ensure that adequate protective equipment is provided. The most important analyses refer to faults which can lead to excessive fuel element temperatures arising from an increase in power or a reduction in cooling capacity. They include the possibility of unintended control rod withdrawal at power or at start-up, coolant flow failure, pressure circuit failure, loss of boiler feed water, and failure of electric power. The paper reviews the protective equipment, and the policy for reactor safety assessments which include application of maximum credible accident philosophy and later the limited use of reliability and probability methods. Some of the Generating Boards' reactors are now more than half way through their planned working lives and during this time safety protective equipment has occasionally been brought into operation, often for spurious reasons. The general performance, of safety equipment is reviewed particularly for incidents such as main turbo-alternator trip, circulator failure, fuel element failures and other similar events, and some problems which have given rise to

Frequency and distribution of leakages in steam generators of gas-cooled reactors

International Nuclear Information System (INIS)

Bongratz, R.; Breitbach, G.; Wolters, J.

1988-01-01

In gas cooled reactors with graphitic primary circuit structures - such as HTR, AGR or Magnox - the water ingress is an event of great safety concern. Water or steam entering the primary circuit react with the hot graphite and carbon-oxide and hydrogen are produced. As the most important initiating event a leak in a steam generator must be taken into account. From the safety point of view as well as for availability reasons it is necessary to construct reliable boilers. Thus the occurrence of a boiler leak should be a rare event. In the context of a probabilistic safety study for an HTR-Project much effort was invested to get information about the frequency and the size distribution of tube failures in steam generators of gas cooled reactors. The main data base was the boiler tube failure statistics of United Kingdom gas cooled reactors. The data were selected and applied to a modern HTR steam generator design. A review of the data showed that the failure frequency is not connected with the load level (pressures, temperatures) or with the geometric size of the heating surface of the boiler. Design, construction, fabrication, examination and operation conditions have the greatest influence an the failure frequency but they are practically not to be quantified. The typical leak develops from smallest size. By erosion effects of the entering water or steam it is enlarged to perhaps some mm 2 , then usually it is detected by moisture monitors. Sudden tube breaks were not reported in the investigated period. As a rule boiler leaks in gas cooled reactors are much more, rare then leaks in steam generators of light water reactors and fossil fired boilers. (author)

Assessment of End-Plug Welding of Fuel Elements; Evaluation des Soudures Terminales des Elements Combustibles; Otsenka kachestva privarki kontsevoj probki toplivnykh ehlementov; Inspeccion de la Soldadura del Tapon Terminal de los Elementos Combustibles

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Y.; Aoki, T. [Tokai Refinery, Atomic Fuel Corporation (Japan)

1965-10-15

It is very important to correlate the testing results with the performance in reactor service, as well as to develop non-destructive testing techniques themselves. However, it is rather difficult to obtain these correlations because of high expense and radioactivity. Several kinds of assessments in out-of-pile state were carried out simulating the in-reactor conditions. Some details of these assessments on JRR-3 fuel elements are described. The reactor is a heavy-water moderated and cooled research reactor of 10-MW capacity, with aluminium-clad metallic uranium fuel elements. As the elements have only mechanical bonding between cladding and core, there might be a tensile stress at the end plug as a result of irradiation growth of the uranium core. Thermal cycling will cause a similar stress in the welds. Preferential corrosion by hot water might occur in the vicinity of the welds because of the difference of micro-structure. It is essential to keep leak-tightness during and after the reactor service. Specially designed specimens were used for tensile testing, high-temperature creep testing, thermal cycling and corrosion testing. Many sorts of weld characters were examined non-destructively before the tests and leak-checked at intervals of the tests. Evaluations of these results may be used for the establishment of inspection standards such as X-ray radiography and visual inspection of the end-plug welding. Some other results on Magnox-clad and Zircaloy clad fuel elements will also be described. (author) [French] Il est tres important de mettre en correlation les resultats d'essais et les performances d'un reacteur en service, et d'ameliorer les methodes d'essais non destructifs. Toutefois, cette correlation est souvent difficile S obtenir du fait des depenses elevees necessaires et de difficultes tenant S la radioactivite. Plusieurs sortes d'evaluations ont ete faites hors pile en simulant les conditions en pile. Le memoire donne certains details des evaluations

Extended storage of spent fuel

International Nuclear Information System (INIS)

1992-10-01

This document is the final report on the IAEA Co-ordinated Research Programme on the Behaviour of Spent Fuel and Storage Facility Components during Long Term Storage (BEFAST-II, 1986-1991). It contains the results on wet and dry spent fuel storage technologies obtained from 16 organizations representing 13 countries who participated in the co-ordinated research programme. Considerable quantities of spent fuel continue to arise and accumulate. Many countries are investigating the option of extended spent fuel storage prior to reprocessing or fuel disposal. Wet storage continues to predominate as an established technology with the construction of additional away-from-reactor storage pools. However, dry storage is increasingly used with most participants considering dry storage concepts for the longer term. Depending on the cladding type options of dry storage in air or inert gas are proposed. Dry storage is becoming widely used as a supplement to wet storage for zirconium alloy clad oxide fuels. Storage periods as long as under wet conditions appear to be feasible. Dry storage will also continue to be used for Al clad and Magnox type fuel. Enhancement of wet storage capacity will remain an important activity. Rod consolidation to increase wet storage capacity will continue in the UK and is being evaluated for LWR fuel in the USA, and may start in some other countries. High density storage racks have been successfully introduced in many existing pools and are planned for future facilities. For extremely long wet storage (≥50 years), there is a need to continue work on fuel integrity investigations and LWR fuel performance modelling. it might be that pool component performance in some cases could be more limiting than the FA storage performance. It is desirable to make concerted efforts in the field of corrosion monitoring and prediction of fuel cladding and poll component behaviour in order to maintain good experience of wet storage. Refs, figs and tabs

Development of a Systematic Approach to Post-Operation Clean Out at Sellafield

International Nuclear Information System (INIS)

Macpherson, Ian; Dunlop, Alister

2016-01-01

Post Operational Clean Out (POCO) relates to the activities undertaken directly after commercial operations cease to remove residual activity and facilitate decommissioning of a nuclear facility. Historically the transition of Sellafield facilities has proved sub-optimal resulting in loss of critical plant knowledge, additional cost and protracted delivery timelines. The move from reprocessing in Magnox and Thorp to POCO is a significant transition facing the site, with a large number of diverse facilities scheduled to cease operations over the next 15 years. In order to ensure that the facilities are dealt with in a consistent manner, that supports both Site and Nuclear Decommissioning Authority (NDA) strategies, the POCO programme has been established across the Sellafield Operations Division. Primary aims of the POCO programme are: - Risk and Hazard Reduction; - Enabling redeployment of resource and capability; - Life-cycle cost reduction; - Enhanced Reputation. Transition preparations will cover process, organisation, technology and information. Knowledge is a key output of POCO: the creation of records of the plant configuration and status to enable and support the safe and effective eventual decommissioning of the plant. The consistent approach that has been developed will: - Ensure the smooth transition from operations into POCO, and then into surveillance and maintenance. - Maximise the potential of facilities to support other site activities prior to POCO. - Optimise the facility schedules within the overall POCO programme, to ensure timely decoupling. - Define and manage the resource demands and capabilities prior to and during POCO. - Provide a baseline configuration for each facility at the end of the POCO phase. - Encourage and enable knowledge management to ensure that subsequent decommissioning activities are informed and supported. - Look for opportunities to progress housekeeping and co-processing activities so as to reduce inventory and make best

From the nuclear world

International Nuclear Information System (INIS)

Anon.

2016-01-01

This document gathers pieces of information concerning nuclear industry worldwide. The most relevant are the following ones. CGN (China General Nuclear) will launched in 2017 the construction of a prototype of a small transportable modular reactor whose purpose is to produce electricity on a remote place like an island or aboard a boat for long-term missions. The Wylfa reactor (490 MWe) was decommissioned on December 30., 2015. Wylfa was the last Magnox type reactor operating in the world. In France a campaign of information and iodine drug dispatching has been launched for people living near nuclear power plants. The global cost of the CIGEO project whose aim is the disposal of high-level radioactive wastes has been estimated to 25 billions euros including construction costs, operating costs over a 100 year period and dismantling costs. The European Commission has warned France that the financial provisions made for the dismantling of nuclear facilities and the processing of the consequent wastes are not sufficient to cover the future costs. 4 reactors with a power of 1400 MWe each, are being built on the Barakah site in Abu Dhabi, works are on time and the first unit may operate end 2016. Wikileaks has accused AREVA of not taking all necessary measures for the protection of its employees at the Bakouma mine. AREVA denies the charges and affirms that regulations and safety requirements are the same as for its French sites whatever the country. The initiative 'Nuclear for Climate' gathering pro-nuclear associations worldwide, intends to remind the international community that nuclear energy is an important tool to fight climate change. The French site for the disposal of low-level radioactive wastes is facing saturation in the very short term while the volume of such wastes is expected to soar in the next decades as the dismantling programmes will gain in importance. A new policy for the management of such wastes is needed. (A.C.)

A review of the United Kingdom fast reactor programme

International Nuclear Information System (INIS)

Bramman, J.I.; Hickey, H.B.; Whitlow, W.H.; Frew, J.D.; Gregory, C.V.

1990-01-01

Total energy consumption in the UK in 1989 was 340 million tonnes of coal or coal equivalent, made up as follows: coal 31%, petroleum 35%, natural gas 24%, nuclear electricity 8%, hydroelectricity 1% and imported electricity 1%. About half of the nuclear electricity generated came from 14 Advanced Gas-Cooled Reactors (AGRs) and about half from the 24 older gas-cooled Magnox reactors, one Steam-Generating Heavy-Water Reactor (SGHWR) and one fast reactor (the Prototype Fast Reactor, PFR, at Dounreay). The privatization of the Electricity Supply Industry (ESI) in the UK is proceeding. On 9 November 1989, however, it was announced by the Secretary of State for Energy that the privatization plan would be changed and that the CEGB's nuclear stations were to remain in state ownership, through the formation of an additional company, Nuclear Electric. At the same time, the Secretary of State for Scotland announced the formation of a similar state-owned company, Scottish Nuclear. Nuclear Electric was asked, in the interim, to examine priorities in the whole nuclear field with particular reference to the improvement of the economics and performance of existing reactors, to the development of the Sizewell and alternative reactors and to the development of longer-term options such as the fast reactor and fusion. Nuclear Electric has been asked to formulate its new policy by June 1990. The PFR programme will continue to be funded by the UK government until March 1994. AEA Technology is endeavouring to find alternative funding to maintain the operation of the PFR until at least the year 2000. The House of Commons Select Committee on Energy stated in its report that the fast reactor ''is a matter for the British Government to foster as a long-term option for the generation of electricity in this country'', and recommended that in the interim the Government reassesses its position on this new technology in the light of increasing concern about CO 2 emissions and the long

Examination of long-stored uranium metal

Energy Technology Data Exchange (ETDEWEB)

Gate, A.M.; Hambley, D.I. [National Nuclear Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom)

2013-07-01

A small quantity of unirradiated uranium from Magnox fuel elements is currently held in archive storage. Some of these samples date back to the late fifties. This material has been stored, untreated, in unsealed containers in air at ambient temperature, humidity and pressure conditions. Such conditions are relevant to those that may exist in a passive storage facility. A sample of this material has been subject to optical, electron-optical and Raman spectroscopic examination to determine the extent of corrosion and the composition of corrosion product arising from long-term, low-temperature oxidation of uranium metal in air. The examinations have established that, even after a period in excess of 40 years, there was no observable spalling of uranium oxide from the sample during storage. The extent of oxidation of the metal, derived by SEM analysis, was slight and insignificant in relation to overall structural stability of the material. Raman spectroscopy data showed that the bulk of the oxide layer was comprised of hyper-stoichiometric UO{sub 2}, with U{sub 4}O{sub 9} being the dominant component. The oxygen/uranium ratio was observed to be decreased at the metal/oxide interface, with a very thin layer that consisted of mainly UO{sub 2} at the metal surface. At the oxide/air interface, a very thin U{sub 3}O{sub 8} layer was detected. U{sub 4}O{sub 9} is relatively mechanically stable, due to a significantly higher density than UO{sub 2} and U{sub 3}O{sub 8}. It is likely that the lower internal stresses in the thick U{sub 4}O{sub 9} layer have resulted in less oxide film cracking than would be expected from UO{sub 2} or U{sub 3}O{sub 8} and hence the low oxidation rate observed. These results suggest that storage of uranium metal in air over decades is a safe and credible option. (authors)

Reactor decommissioning strategy: a new start for BNFL

International Nuclear Information System (INIS)

Woollam, P.; Nurden, P.

2001-01-01

The key points of BNFL Magnox Electric's revised waste management and reactor decommissioning strategy for the reactor sites are enlisted. Reactors will be defuelled as soon as practicable after shutdown. Predominantly Caesium contaminated plant will be dismantled when it is no longer needed. Cobalt contaminated plant such as boilers will remain in position until the reactors are dismantled, but appropriate decontamination technology will be regularly reviewed. All buildings except the reactor buildings will be dismantled as soon as practicable after they are no longer needed. Operational ILW, except some activated components, will be retrieved and packaged during the Care and Maintenance preparation period. All wastes will be stored on site, and handled in the long term in accordance with Government policy. Reactor buildings and their residual contents will be placed in a passive safe storage Care and Maintenance condition in a manner appropriate for the site. Contaminated land will be managed to maintain public safety. The reactors will be finally dismantled in a sequenced programme with a start date and duration to be decided at the appropriate time in the light of circumstances prevalent at that time. Currently, the Company is considering a sequenced programme across all sites, notionally beginning around 100 years from station shutdown, leading to a range of deferral periods. For provisioning purposes, the Company has costed a strategy involving reactor dismantling deferrals ranging from 85 to about 105 years in order to demonstrate prudent provisioning to meet its liabilities. A risk provision to reflect the potential for shorter deferral periods is included in the cost estimates. The end point for reactor decommissioning is site clearance and delicensing, based on the assumption that a reasonably practicable interpretation of the 'no danger' clause in the Nuclear Installations Act 1965 (as amended) can be developed. In line with Government policy, and taking

Progress in the development of tooling and dismantling methodologies for the Windscale advanced gas cooled reactor (WAGR)

International Nuclear Information System (INIS)

Cross, M.T.; Wareing, M.I.; Dixon, C.

1998-01-01

Decommissioning of the Windscale Advanced Gas-Cooled Reactor (WAGR) is a major UK reactor decommissioning project co-funded by the UK Government, the European Commission and Magnox Electric. WAGR was a CO 2 cooled, graphite moderated reactor which served as a test bed for the development of Advanced Gas-Cooled Reactor technology in the UK. It operated from 1963 until shutdown in 1981. AEA Technology plc are currently the Managing Agents on behalf of UKAEA for the WAGR decommissioning project and are responsible for the co-ordination of the project up to the point when the contents of the reactor core and associated radioactive materials are removed and either disposed of or packaged for disposal at some time in the future. Decommissioning has progressed to the point where the reactor has been dismantled down to the level of the hot gas collection manifold with the removal of the top biological shield, the refuelling standpipes and the top section of the reactor pressure vessel. The 4 heat exchangers have also been removed and committed to shallow land burial. This paper describes the work carried out by AEA Technology under separate contracts of UKAEA in developing some of the equipment and deployment methods for the next phase of active operations required in preparation for the dismantling of the core structure. Most recent work has concentrated on the development of specialist tooling for removal of items of operational waste stored within the reactor core, equipment for cutting and removal of the highly radioactive stainless steel 'loop' pressure tubes, diamond wire cutting equipment for sectioning large diameter pipework, and equipment for dismantling the reactor neutron shield. The paper emphasises the process of adaptation and extension of existing technologies for cost-effective application in the decommissioning environment, the need for adequate forward planning of decommissioning methodologies together with large-scale 'mock-up' testing of equipment to

Effect of humic acid & bacterial exudates on sorption-desorption interactions of 90Sr with brucite.

Science.gov (United States)

Ashworth, Hollie; Abrahamsen-Mills, Liam; Bryan, Nick; Foster, Lynn; Lloyd, Jonathan R; Kellet, Simon; Heath, Sarah

2018-05-18

One of the nuclear fuel storage ponds at Sellafield (United Kingdom) is open to the air, and has contained a significant inventory of corroded magnox fuel and sludge for several decades. As a result, some fission products have also been released into solution. 90Sr is known to constitute a small mass of the radionuclides present in the pond, but due to its solubility and activity, it is at risk of challenging effluent discharge limits. The sludge is predominantly composed of brucite (Mg(OH)2), and organic molecules are known to be present in the pond liquor with occasional algal blooms restricting visibility. Understanding the chemical interactions of these components is important to inform ongoing sludge retrievals and effluent management. Additionally, interactions of radionuclides with organics at high pH will be an important consideration for the evolution of cementitious backfilled disposal sites in the UK. Batch sorption-desorption experiments were performed with brucite, 90Sr and natural organic matter (NOM) (humic acid (HA) and Pseudanabaena catenata cyanobacterial growth supernatant) in both binary and ternary systems at high pH. Ionic strength, pH and order of addition of components were varied. 90Sr was shown not to interact strongly with the bulk brucite surface in binary systems under pH conditions relevant to the pond. HA in both binary and ternary systems demonstrated a strong affinity for the brucite surface. Ternary systems containing HA demonstrated enhanced sorption of 90Sr at pH 11.5 and vice versa, likely via formation of strontium-humate complexes regardless of the order of addition of components. The distribution coefficients show HA sorption to be reversible at all pH values studied, and it appeared to control 90Sr behaviour at pH 11.5. Ternary systems containing cyanobacterial supernatant demonstrated a difference in 90Sr behaviour when the culture had been subjected to irradiation in the first stages of its growth.

Decommissioning of nuclear facilities

International Nuclear Information System (INIS)

Lunning, W.H.

1977-01-01

Collaborative studies are in progress in the U.K. between the U.K.A.E.A., the Generating Boards and other outside bodies, to identify the development issues and practical aspects of decommissioning redundant nuclear facilities. The various types of U.K.A.E.A. experimental reactors (D.F.R., W.A.G.R , S.G.H.W.R.) in support of the nuclear power development programme, together with the currently operating commercial 26 Magnox reactors in 11 stations, totalling some 5 GW will be retired before the end of the century and attention is focussed on these. The actual timing of withdrawal from service will be dictated by development programme requirements in the case of experimental reactors and by commercial and technical considerations in the case of electricity production reactors. Decommissioning studies have so far been confined to technical appraisals including the sequence logic of achieving specific objectives and are based on the generally accepted three stage progression. Stage 1, which is essentially a defuelling and coolant removal operation, is an interim phase. Stage 2 is a storage situation, the duration of which will be influenced by environmental pressures or economic factors including the re-use of existing sites. Stage 3, which implies removal of all active and non-active waste material and returning the site to general use, must be the ultimate objective. The engineering features and the radioactive inventory of the system must be assessed in detail to avoid personnel or environmental hazards during Stage 2. These factors will also influence decisions on the degree of Stage 2 decommissioning and its duration, bearing in mind that for Stage 3 activation may govern the waste disposal route and the associated radiation man-rem exposure during dismantling. Ideally, planning for decommissioning should be considered at the design stage of the facility. An objective of present studies is to identify features which would assist decommissioning of future systems

Pyrolysis and its potential use in nuclear graphite disposal

International Nuclear Information System (INIS)

Mason, J.B.; Bradbury, D.

2001-01-01

Graphite is used as a moderator material in a number of nuclear reactor designs, such as MAGNOX and AGR gas cooled reactors in the United Kingdom and the RBMK design in Russia. During construction the moderator of the reactor is usually installed as an interlocking structure of graphite bricks. At the end of reactor life the graphite moderator, weighing typically 2,000 tonnes, is a radioactive waste which requires eventual management. Radioactive graphite disposal options conventionally include: In-situ SAFESTORE for extended periods to permit manual disassembly of the graphite moderator through decay of short-lived radionuclides. Robotic or manual disassembly of the reactor core followed by disposal of the graphite blocks. Robotic or manual disassembly of the reactor core followed by incineration of the graphite and release of the resulting carbon dioxide Studsvik, Inc. is a nuclear waste management and waste processing company organised to serve the US nuclear utility and government facilities. Studsvik's management and technical staff have a wealth of experience in processing liquid, slurry and solid low level radioactive waste using (amongst others) pyrolysis and steam reforming techniques. Bradtec is a UK company specialising in decontamination and waste management. This paper describes the use of pyrolysis and steam reforming techniques to gasify graphite leading to a low volume off-gas product. This allows the following options/advantages. Safe release of any stored Wigner energy in the graphite. The process can accept small pieces or a water-slurry of graphite, which enables the graphite to be removed from the reactor core by mechanical machining or water cutting techniques, applied remotely in the reactor fuel channels. In certain situations the process could be used to gasify the reactor moderator in-situ. The low volume of the off-gas product enables non-carbon radioactive impurities to be efficiently separated from the off-gas. The off-gas product can

Practical decommissioning experience with nuclear installations in the European Community

International Nuclear Information System (INIS)

Skupinski, E.

1993-01-01

Initiated by the Commission of the European Communities (CEC), this seminar was jointly organized by Kernkraftwerke RWE Bayernwerk GmbH (KRB) and the CEC at Gundremmingen-Guenzburg (D), where the former KRB-A BWR is presently being dismantled. The meeting aimed at gathering a limited number of European experts for the presentation and discussion of operations, the results and conclusions on techniques and procedures presently applied in the dismantling of large-scale nuclear installations in the European Community. Besides the four pilot dismantling projects of the presently running third R and D programme (1989-93) of the European Community on decommissioning of nuclear installations (WAGR, BR-3 PWR, KRB-A BWR and AT-1 FBR fuel reprocessing), the organizers selected the presentation of topics on the following facilities which have a significant scale and/or representative features and are presently being dismantled: the Magnox reprocessing pilot plant at Sellafield, the HWGCR EL4 at Monts d'Arree, the operation of an on-site melting furnace for G2/G3 GCR dismantling waste at Marcoule, an EdF confinement conception of shut-down LWRs for deferred dismantling, and the technical aspects of the Greifswald WWER type NPPs decommissioning. This was completed by a presentation on the decommissioning of material testing reactors in the United Kingdom and by an overview on the conception and implementation of two EC databases on tools, costs and job doses. The seminar concluded with a guided visit of the KRB-A dismantling site. This meeting was attended by managers concerned by the decommissioning of nuclear installations within the European Community, either by practical dismantling work or by decision-making functions. Thereby, the organizers expect to have contributed to the achievement of decommissioning tasks under optimal conditions - with respect to safety and economics - by making available a complete and updated insight into on-going dismantling projects and by

Managing the nuclear legacy in the UK - Progress towards the establishment of the nuclear decommissioning authority

International Nuclear Information System (INIS)

Sellers, Robin M.

2003-01-01

In November 2001, the British Government announced its intention to undertake a radical change in the arrangements for managing public sector civil nuclear liabilities in the UK. The UK Government's proposals for this transformation were published in a White Paper Managing the Nuclear Legacy - A Strategy for Actions published on 4 July 2002. This envisages the establishment of a new organisation, the Nuclear Decommissioning Authority (NDA), responsible to Government and with a remit to ensure that the UK's nuclear legacy is cleaned up safely, securely, cost effectively and in ways which protect the environment. The NDA will be responsible for some twenty UK nuclear sites comprising about 85% of the UK's civil nuclear liabilities. These sites are those currently operated by the United Kingdom Atomic Energy Authority (UKAEA) and British Nuclear Fuels plc (BNFL), and amongst other things include many facilities from the early years of nuclear power etc in the UK, liabilities associated with the Joint European Torus (JET) fusion research project at UKAEA's Culham site, the Magnox nuclear power stations, and the associated facilities at Sellafield for reprocessing. The challenge is to decommission and demolish these facilities, package the radioactive wastes ready for disposal and remediate the sites, taking into account the uncertainties associated with many of the older facilities and the potential technical novelty of the processes that will have to be deployed to achieve this. To prepare the way for the NDA, a special team has been established within the UK Department of Trade and Industry. This team, known as the Liabilities Management Unit (LMU), includes staff from both private and public sectors, and is supported by a partner contractor (Bechtel Management Company Ltd) who bring high quality, experienced project management skills to the team. LMU's principal tasks are: - Acquiring a detailed knowledge of BNFL and UKAEA liabilities; - Establishing common

Sogin enriched uranium extraction (EUREX) plant spent fuel pool cleaning and decontamination utilizing the Smart Safe solution

International Nuclear Information System (INIS)

Denton, M.S.; Gili, M.; Nasta, M.; Quintiliani, R.; Caccia, G.; Botzen, W.; Forrester, K.

2009-01-01

SOGIN's EUREX facility in Italy was developed as a pilot plant functional testing laboratory for spent fuel reprocessing. This facility was operated successfully for many years since 1970 and was eventually shutdown consistent with Italy's suspension of all nuclear operations. At the time of suspension, the EUREX facility still had spent nuclear fuel assemblies in storage from a nearby PWR. Other fuel assemblies from an Italian AGR had remained stored in the spent fuel pool for the 20 years or so waiting for removal and reprocessing abroad. Being Magnox fuel elements, their recovery for the transport produced a huge amount of sludge in the pool. During this time, sediment, dirt, corrosion products, fuel cladding, etc. has collected within the fuel pool as a crud layer dispersed throughout. Most of this crud has accumulated on the horizontal surfaces of the pool and fuel element assemblies, while some remains as a suspended colloidal material. Furthermore many other contaminated metal components, used during the operation years, where still inside the pool. Due to a pool leak discovered in 2006, SOGIN speeded up its pool decommissioning program, making also available the transfer of the spent fuel to a nearby interim repository, with the goal to completely drain the pool in the shortest period of time. In order for SOGIN to successfully transfer the fuel assemblies from their current storage basket locations to the spent fuel transfer cask, the bulk of the crud needed to be removed. This cleanup operation was deemed necessary to minimize the suspension of contamination in the water during underwater handling operations. This would reduce the decontamination efforts on the transfer cask upon removal, once loaded with the spent fuel, and enhance safety by reducing potential underwater visibility issues. The operations were completed in July 2008 with the release to the environment of the pool water, thoroughly purified and without any relevant radiological impact. The

Managing the nuclear legacy n the UK: Progress towards the establishment of the Nuclear Decommissioning Authority

International Nuclear Information System (INIS)

Sellers, R.M.

2003-01-01

In November 2001, the British Government announced its intention to undertake a radical revision of the arrangements for managing public sector civil nuclear liabilities in the UK. Its proposals for this transformation were published in a White Paper 'Managing the Nuclear Legacy - A Strategy for Action' published on 4 July 2002. This calls for the formation of a new organisation, originally referred to as the Liabilities Management Authority, but since renamed the Nuclear Decommissioning Authority (NDA), responsible to Government and with a remit to ensure that the UK's nuclear legacy is cleaned up safely, securely, cost effectively and in ways which protect the environment. The NDA will be responsible for some twenty-one UK nuclear sites comprising about 85% of the UK's civil nuclear liabilities. These sites are those currently operated by the United Kingdom Atomic Energy Authority (UKAEA) and British Nuclear Fuels plc (BNFL), and amongst other things include many facilities from the early years of nuclear power etc in the UK, liabilities associated with the Joint European Torus (JET) fusion research project at UKAEA's Culham site, the Magnox nuclear power stations, and the associated facilities at Sellafield for reprocessing as well as those associated with the UK's fast reactor programme based at Dounreay. The challenge is to decommission and dismantle these facilities, package the radioactive wastes ready for disposal and remedy the sites, taking into account the uncertainties associated with many of the older facilities and the potential technical novelty of the processes that will have to be deployed to achieve this. This paper is concerned with the work of the Liabilities Management Unit (LMU) in preparing the way for the NDA and what it has achieved in its first eighteen months. The following issues are addressed: The Liabilities Management Unit and its remit (which presents the LMU Functional Groups and their responsibilities); Acquiring a detailed

NEET and TIDY

International Nuclear Information System (INIS)

Hunt, A.J.

2010-01-01

Magnox North - Wylfa Nuclear Power Station have recognised that due to the remote location of the power station on Anglesey, North Wales does not offer up opportunities to young people easily whether in the educational systems or not. Aware of the skills issues they are actively engaged in promoting the links between business and education that are needed to ensure a nuclear capable workforce for the future. The skill sets required at the nuclear plant are not always suited for academics and many positions are preferential for those with vocational skills. These skills can be gained while in the classroom with the right inputs, however, the NEETs do not have the luxury of the classroom and are often not suited to that type of learning environment. Realising that these youngsters need an alternative learning style Wylfa have been working with various agencies in support of providing employment experiences for the NEETs. The paper considers the background of the skills gaps and the different ways this can be addressed. It provides detail of the various employment experiences being provided at Wylfa and how these interface with skills gaps. Employment experiences are provided through: - graduate placement scheme (Post graduate); - apprenticeship programme (16 - 19 year olds); - summer placement (17 - 25 year olds); - work experience (14 and 16 year olds); - NEETs programme (16 +). Wylfa is aware of the potential skill base that these young people posses and given the right opportunities to become engaged and motivated realise they could support the much needed vocational skills. The paper investigates the benefits of the NEETs programme being provided at Wylfa. It describes the processes involved in appointing the relevant person and the type of work they are given to experience. A sterile series of activity is provided to the individual who is appointed a mentor and team leader to guide them through their time on the programme. The young person's perspective of an

Permanent cessation of Tokai power plant's operation

International Nuclear Information System (INIS)

Satoh, T.

1998-01-01

Tokai power plant (166MWe, Magnox type: GCR) is the first commercial reactor in Japan and has been kept operating stable since its commissioning in July 1996. During this period it has produced electricity of approximately 27.7 billion KWh (as of March 1997) and its stable operation has contributed greatly to the stable supply of electricity in Japan. Furthermore, technologies in various fields have been developed, demonstrated and accumulated through the construction and operation of Tokai power plant. It also contributes to training for many nuclear engineers, and constructions and operations of nuclear power stations by other Japanese power companies. As a pioneer, it has been achieved to develop and popularize Japanese nuclear power generation. On the other hand, Tokai power plant has small capacity in its electric power output, even though the size of the reactor and heat exchangers are rather bigger than those of LWR due to the characteristics of GCR. Therefore, the generation cost is higher than the LWR. Since there is no plant whose reactor type is the same as that of Tokai power plant, the costs for maintenance and fuel cycle are relatively higher than that of LWR. Finally we concluded that the longer we operate it, the less we can take advantage of it economically. As a result of the evaluation for the future operation of Tokai power plant including the current status for supply of electricity by the Japanese utilities and study of decommissioning by Japanese government, we decided to have a plan of stopping its commercial operation of Tokai power plant in the end of March, 1998, when we completely consume its fuel that we possess. From now on, we set about performing necessary studies and researches on the field of plant characterization, remote-cutting, waste disposal for carrying out the decommissioning of Tokai power plant safely and economically. We are going to prepare the decommissioning planning for Tokai power plant in a few years based on the

Serpentine tube heat transfer characteristic under accident condition in gas cooled reactors

International Nuclear Information System (INIS)

Abouhadra, D.S.; Byrne, J.E.

2004-01-01

In nuclear reactors of the Magnox or advanced gas Cooled type, serpentine tubing is used in some designs to generate steam in a once through arrangement. The calculation of accident conditions using two phase flow codes requires knowledge of the heat transfer behavior of the boiler steam side. A series of experiments to study the blowdown characteristics of a typical serpentine boiler section was devised in order to validate the MARTHA section of the MACE code used by nuclear Electric. The tests were carried out on the Thermal Hydraulics Experimental Research Assembly (THERA) loop at Manchester University. The Thermal Hydraulic Experimental Research Assembly was designed to operate with pressures up to 180 bar and temperatures of 450degC. The geometry and dimensions of this test section were similar to part of a gas cooled reactor boiler of the Hinkley Point design. Blowdown from a pressure of 60 bar with subcoolings of 5degC, 50degC, 100degC formed the main part of the programme. A set of tests was conducted using discharge orifices of different sizes to produce depressurization times from 30 s to 10 mins, and in a few cases, the duration of blowdown approached 1 hour. These times were defined using the criterion of blowdown end as a final pressure of 10% of the initial pressure. Pressures, wall and fluid temperatures were all measured at average time intervals of 1.1s during the excursion and an inventory of the remaining water content in the serpentine was taken when the blowdown ended. Some tests were also conducted at an initial pressure of 30 bar. The results obtained show interesting stratification effects for the relatively fast discharge, with substantial wall circumferential temperature variations. For these tests, a relatively small water inventory remained after blowdown. The discharge characteristics of the serpentine in terms of orifice size have been mapped, and tests at 30 bar show the equivalence in terms of orifice size have been mapped

Some investigations into the behaviour of plutonium in the marine environment

International Nuclear Information System (INIS)

Hetherington, J.A.; Jefferies, D.F.; Lovett, M.B.

1975-01-01

Plutonium and other transuranic elements are produced during the operation of magnox reactors, although they do not usually present any problems of waste management until the fuel reaches the reprocessing stage. At this stage one of the chief aims is to separate and recover the plutonium from the depleted uranium and the fission products, the incentive being the value of plutonium itself as a nuclear fuel particularly for the fast breeder reactors. For this reason the amounts of plutonium appearing in the low activity waste streams for discharge to the environment are usually small, and their radiological impact insignificant compared with that of the more abundant fission products. However, with the prospect of use of large quantities of plutonium in the fast reactors, considerable interest surrounds all aspects of the properties of plutonium, and in an attempt to give a fuller understanding of the behaviour of plutonium in the marine environment use has been made of the small amounts which have been discharged in recent years to the north-east Irish Sea from the fuel reprocessing plant at Windscale in Cumbria. Details of the amounts of 239 Pu and 240 Pu discharged to sea are given and the resultant measured concentrations of the isotopes in the water throughout the Irish Sea are shown. The distribution of plutonium in sea water is shown to follow the same basic pattern as the fission products, details of which have been reported previously. By comparing the concentration gradients with distance from the point of discharge for plutonium and caesium, a value for the rate of loss of plutonium from the water to the other important compartment, namely the sediment, has been deduced. Measurements have been made of 239 Pu and 240 Pu in seabed and estuarine sediments and by combining these with the water data values of the concentration factor for the nuclide in sediment have been calculated. The results of a number of core samples have been used to calculate an

Derivation of a radionuclide inventory for irradiated graphite-chlorine-36 inventory determination

International Nuclear Information System (INIS)

Brown, F.J.; Palmer, J.D.; Wood, P.

2001-01-01

The irradiation of materials in nuclear reactors results in neutron activation of component elements. Irradiated graphite wastes arise from their use in UK gas-cooled research and commercial reactor cores, and in fuel element components, where the graphite has acted as the neutron moderator. During irradiation the residual chlorine, which was used to purify the graphite during manufacture, is activated to chlorine-36. This isotope is long-lived and poorly retarded by geological barriers, and may therefore be a key radionuclide with respect to post-closure disposal facilities performance. United Kingdom Nirex Limited, currently responsible for the development of a disposal route for intermediate-level radioactive wastes in the UK, carried out a major research programme to support an overall assessment of the chlorine-36 activity of all wastes including graphite reactor components. The various UK gas cooled reactors reactors have used a range of graphite components made from diverse graphite types; this has necessitated a systematic programme to cover the wide range of graphite and production processes. The programme consisted of: precursor measurements - on the surface and/or bulk of representative samples of relevant materials, using specially developed methods; transfer studies - to quantify the potential for transfer of Cl-36 into and between waste streams during irradiation of graphite; theoretical assessments - to support the calculational methodology; actual measurements - to confirm the modelling. For graphite, a total of 458 measurements on samples from 57 batches were performed, to provide a detailed understanding of the composition of nuclear graphite. The work has resulted in the generation of probability density functions (PDF) for the mean chlorine concentration of three classes of graphite: fuel element graphite; Magnox moderator and reflector graphite and AGR reflector graphite; AGR moderator graphite. Transfer studies have shown that a significant

Long Term Behaviour of 14C and Stability Assessments of Graphite Under Repository Conditions

International Nuclear Information System (INIS)

Jones, Abbie N.; McDermott, Lorraine; Worth, Robert; Hagos, Bereket; Black, Greg; Marsden, Barry J

2016-01-01

The key objectives of the University of Manchester’s nuclear graphite research within the CRP are to provide analysis on the long term behaviour and stability assessments of irradiated graphite waste. The research will concentrate on isotopic 14 C mobility under repository environments. This also requires an understanding the long-term behaviour of the final waste form under repository conditions. Procedures to evaluate the long term leaching properties of radionuclides from irradiated graphite waste has been developed by combining ANSI 16.1 (USA) and NEN 7345 (Netherlands) standardised diffusion leaching techniques. The ANSI 16.1 standard has been followed to acquire the leachates and to determine the leach rate and diffusion coefficient. The NEN 7345 standard technique has been used to determine the diffusion mechanism of radionuclides. The investigation employs simulated Drigg groundwater as a leachant using semi-dynamic technique for the production of leachate specimens. Analysis of 3 H and 14 C activity release from Magnox graphite was measured using liquid scintillating counting. Preliminary results show that there is an initial high release of activity and decreases when the leaching period increases. This may be due to the depletion of contaminants that were initially bound by the internal pore networks and the free surface. During the leaching test approximately 275.33 ± 18.20 Bq of 3 H and 106.26 ± 7.01 Bq of 14 C was released into the leachant within 91 days. The work reported herein contributed several key findings to the international work on graphite leaching to offer guidance leading toward obtaining leaching data in the future: (a) the effective diffusion coefficient for 14 C from graphite waste has been determined. The diffusion process for 14 C has two stages resulting two different values of diffusion coefficient, i.e., for the fast and slow components; (b) the controlling leaching mechanism for 3 H radionuclide from graphite is shown to be

The siting of UK nuclear reactors.

Science.gov (United States)

Grimston, Malcolm; Nuttall, William J; Vaughan, Geoff

2014-06-01

B (the first and so far only PWR power reactor in the UK) being colocated with an early Magnox station on the rural Suffolk coast. Renewed interest in nuclear new build from 2005 onward led to a number of sites being identified for new reactors before 2025, all having previously hosted nuclear stations and including the semi-urban locations of the 1960s and 1970s. Finally, some speculative comments are made as to what a 'fifth phase' starting in 2025 might look like.

Experiences in the emptying of waste silos containing solid nuclear waste from graphite- moderated reactors

International Nuclear Information System (INIS)

Wall, S.; Schwarz, T.

2003-01-01

Before reactor sites can be handed over for ultimate decommissioning, at some sites silos containing waste from operations need to be emptied. The form and physical condition of the waste demands sophisticated retrieval technologies taking into account the onsite situation in terms of infrastructure and silo geometry. Furthermore, in the case of graphite moderated reactors, this waste usually includes several tonnes of graphite waste requiring special HVAC and dust handling measures. RWE NUKEM Group has already performed several contracts dealing with such emptying tasks. Of particular interest for the upcoming decommissioning projects in France might be the activities at Vandellos, Spain and Trawsfynnyd, UK. Retrieval System for Vandellos NPP is discussed. Following an international competitive tender exercise, RWE NUKEM won the contract to provide a turn-key retrieval system. This involved the design, manufacture and installation of a system built around the modules of a 200 kg capacity version of the ARTISAN manipulator system. The ARTISAN 200 manipulator, with remote slave arm detach facility, was deployed on a telescopic mast inserted into the silos through the roof penetrations. The manipulator deployed a range of tools to gather the waste and load it into a transfer basket, deployed through an adjacent penetration. After commissioning, the system cleared the vaults in less than the scheduled period with no failures. At the Trawsfynnyd Magnox plants two types of intermediate level waste (ILW) accumulated on site; namely Miscellaneous Activated Components (MAC) and Fuel Element Debris (FED). MAC is predominantly components that have been activated by the reactor core and then discharged. FED mainly consists of fuel cladding produced when fuel elements were prepared for dispatch to the reprocessing facility. RWE NUKEM Ltd. was awarded a contract to design, supply, commission and operate equipment to retrieve, pack and immobilize the two waste streams. Major

Advertising is magic

International Nuclear Information System (INIS)

Haskins, Louise

1999-01-01

Full text: Now in its fourth year, BNFL's advertising strategy continues to evolve and build upon the communication achievements of previous years. The case study this year will reflect upon progress so far and will concentrate specifically on the 1998 campaign development. It will begin by briefly reiterating the role we believe advertising plays in the communications mix and by recapping on the theoretical framework upon which the strategy continues to be based. Last year, I presented a case study on the development of BNFL's second television advertisement and supporting media. This year, I will present opinion research data which indicates that BNFL has, indeed, begun to detach itself from the contentious debate which surrounds the nuclear industry in general. Verbatim comments from respondents demonstrate that BNFL is now being perceived more widely within the UK as a successful corporate entity. The presentation will concentrate on the decision-making and research process which led us to select the content of our third advertising campaign. One key consideration being the impact of BNR:s merger with Magnox Electric plc and how their activity was incorporated into the overall advertising strategy. Having established key image characteristics through describing BNFL's scientific achievements and, more recently, BNFL's fuel recycling capabilities, the presentation will outline why this time we have opted for a total capability' advertisement whilst endeavouring to retain the five key image criteria which are at the heart of the strategy. Specific areas covered will include our clearance of the advertisement through the UK's advertising regulatory bodies (the Broadcast Advertising Clearance Centre (BACC) and the Independent Television Commission (ITQ). This in itself will demonstrate the importance of gaining detailed substantiation and legal clearance of the advertising claims made. Finally, we will share our experiences of each production phase, not least, the

COGEMA Experience in Uranous Nitrate Preparation

International Nuclear Information System (INIS)

Tison, E.; Bretault, Ph.

2006-01-01

Separation and purification of plutonium by PUREX process is based on a sequence of extraction and back extraction which requires reducing plutonium Pu IV (extractable form) into Pu III (inextractable form) Different reducers can be used to reduce Pu IV into Pu III. Early plants such as that for Magnox fuel at Sellafield used ferrous sulfamate while UP 1 at Marcoule used uranous sulfamate. These reducers are efficient and easy to prepare but generates ferric and/or sulphate ions and so complicates management of the wastes from the plutonium purification cycle. Recent plants such as UP3 and UP2 800 at La Hague, THORP at Sellafield, and RRP at Rokkasho Mura (currently under tests) use uranous nitrate (U IV) stabilized by hydrazinium nitrate (N 2 H 5 NO 3 ) and hydroxyl ammonium nitrate (HAN). In the French plants, uranous nitrate is used in U-Pu separation and alpha barrier and HAN is used in Pu purification. Compared to sulfamate, U IV does not generate extraneous chemical species and uranyl nitrate (U VI) generated by reducing Pu IV follows the main uranium stream. More over uranous nitrate is prepared from reprocessed purified uranyl nitrate taken at the outlet of the reprocessing plant. Hydrazine and HAN offer the advantage to be salt-free reagents. Uranous nitrate can be generated either by electrolysis or by catalytic hydrogenation process. Electrolytic process has been implemented in early plant UP 1 at Marcoule (when changing reducer from uranous sulfamate to uranous nitrate) and was used again in UP2 plant at La Hague. However, the electrolytic process presented several disadvantages such as a low conversion rate and problems associated with the use of mercury. Electrolysis cells with no mercury were developed for the Eurochemic plant in Belgium and then implemented in the first Japanese reprocessing plant in Tokai-Mura. But finally, in 1975, the electrolytic process was abandoned in favor of the catalytic hydrogenation process developed at La Hague. The

Production of an impermeable composite of irradiated graphite and glass by hot isostatic pressing as a long term leach resistant waste form

International Nuclear Information System (INIS)

Fachinger, Johannes; Muller, Walter; Marsat, Eric; Grosse, Karl-Heinz; Seemann, Richard; Scales, Charlie; Easton, Michael Mark; Anthony Banford

2013-01-01

Around 250,000 tons of irradiated graphite (i-graphite) exists worldwide and can be considered as a current waste or future waste stream. The largest national i-graphite inventory is located in UK (∼ 100,000 tons) with significant quantities also in Russia and France [5]. Most of the i-graphite remains in the cores of shutdown nuclear reactors including the MAGNOX type in UK and the UNGG in France. Whilst there are still operational power reactors with graphite cores, such as the Russian RBMKs and the AGRs in UK, all of them will reach their end of life during the next two decades. The most common reference waste management option of i-graphite is a wet or dry retrieval of the graphite blocks from the reactor core and the grouting of these blocks in a container without further conditioning. This produces large waste package volumes because the encapsulation capacity of the grout is limited and large cavities in the graphite blocks could reduce the packing densities. Packing densities from 0.5 to 1 tons per cubic meter have been assumed for grouting solutions. Furthermore the grout is permeable. This could over time allow the penetration of aqueous phases into the waste block and a potential dissolution and release of radionuclides. As a result particularly highly soluble radionuclides may not be retained by the grout. Vitrification could present an alternative, however a similar waste package volume increase may be expected since the encapsulation capacity of glass is potentially similar to or worse than that of grout. FNAG has developed a process for the production of a graphite-glass composite material called Impermeable Graphite Matrix (IGM) [3]. This process is also applicable to irradiated graphite which allows the manufacturing of an impermeable material without volume increase. Crushed i-graphite is mixed with 20 vol.% of glass and then pressed under vacuum at an elevated temperature in an axial hot vacuum press (HVP). The obtained product has zero or

Production of an impermeable composite of irradiated graphite and glass by hot isostatic pressing as a long term leach resistant waste form

Energy Technology Data Exchange (ETDEWEB)

Fachinger, Johannes; Muller, Walter [FNAG ZU Hanau, Hanau (Germany); Marsat, Eric [FNAG SAS Le Pont de Claix (France); Grosse, Karl-Heinz; Seemann, Richard [ALD Hanau (Germany); Scales, Charlie; Easton, Michael Mark [NNL, Workington (United Kingdom); Anthony Banford [NNL, Warrington (United Kingdom); University of Manchester, Manchester (United Kingdom)

2013-07-01

Around 250,000 tons of irradiated graphite (i-graphite) exists worldwide and can be considered as a current waste or future waste stream. The largest national i-graphite inventory is located in UK (∼ 100,000 tons) with significant quantities also in Russia and France [5]. Most of the i-graphite remains in the cores of shutdown nuclear reactors including the MAGNOX type in UK and the UNGG in France. Whilst there are still operational power reactors with graphite cores, such as the Russian RBMKs and the AGRs in UK, all of them will reach their end of life during the next two decades. The most common reference waste management option of i-graphite is a wet or dry retrieval of the graphite blocks from the reactor core and the grouting of these blocks in a container without further conditioning. This produces large waste package volumes because the encapsulation capacity of the grout is limited and large cavities in the graphite blocks could reduce the packing densities. Packing densities from 0.5 to 1 tons per cubic meter have been assumed for grouting solutions. Furthermore the grout is permeable. This could over time allow the penetration of aqueous phases into the waste block and a potential dissolution and release of radionuclides. As a result particularly highly soluble radionuclides may not be retained by the grout. Vitrification could present an alternative, however a similar waste package volume increase may be expected since the encapsulation capacity of glass is potentially similar to or worse than that of grout. FNAG has developed a process for the production of a graphite-glass composite material called Impermeable Graphite Matrix (IGM) [3]. This process is also applicable to irradiated graphite which allows the manufacturing of an impermeable material without volume increase. Crushed i-graphite is mixed with 20 vol.% of glass and then pressed under vacuum at an elevated temperature in an axial hot vacuum press (HVP). The obtained product has zero or

Reactor Physics Development for Advanced Gas-Cooled Reactors; Recherches en Physique des Reacteurs, pour des Reacteurs Perfectionnes Refroidis par un Gaz; Razrabotka metodov v oblasti reaktornoj fiziki dlya usovershenstvovannogo reaktora s gazovym okhlazhdeniem; Progresos de la Fisica de los Reactores de Tipo Avanzado Refrigerados por Gas

Energy Technology Data Exchange (ETDEWEB)

Moore, J. [United Kingdom Atomic Energy Authority (United Kingdom)

1964-04-15

The paper is a general one reviewing the detailed experimental and theoretical work that has been done during design, development and commissioning of the Windscale AGR. and in general support of development of Advanced Gas-Cooled Reactors for civil power production. The main purpose of the paper is to describe die considerable amount of work that has been necessary to develop adequate theoretical methods for calculating (a) flux distribution and reactivity balance in a complex reactor core, (b) power distribution in complex fuel geometries, and (c) the effect of irradiation on fuel cycles and power distribution. As an introduction reference is made to experimental information and theoretical methods available from work on uranium Magnox systems and the experimental information obtained from the British Industries Collaborative Experimental Programme (BICEP) both of which provided the starting point for development of theoretical methods applicable to AGRs. The approach to critical facility APEX and the zero energy reactor HERO have been used with regular lattice arrangements and with combinations of perturbers such as control rods in them to determine lattice parameters for AGR and to check the theoretical methods developed for dealing with heterogeneous reactor cores. The theoretical methods that have been developed and used to date are known as hetrecontrol and FTD2. Experiments were designed to check detailed features of these methods and measurements on a number of different sized ''reactor'' cores in APEX and HERO were analysed to determine a self-consistent set of lattice constants that fitted the experimental results. These purely empirical constants were the used in hetrecontrol and FTD2 to successfully plan commissioning and choice of the loading pattern for the Windscale AGR. Reference is made to experimental techniques that have been tested and those developed for the particular problems encountered. The methods examined for measurement of reactivity

ORIGEN-based Nuclear Fuel Inventory Module for Fuel Cycle Assessment: Final Project Report

Energy Technology Data Exchange (ETDEWEB)

Skutnik, Steven E. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Nuclear Engineering

2017-06-19

processing, and depletion/decay solvers) can be self-contained into a single executable sequence. Further, to embed this capability into other software environments (such as the Cyclus fuel cycle simulator) requires that Origen’s capabilities be encapsulated into a portable, self-contained library which other codes can then call directly through function calls, thereby directly accessing the solver and data processing capabilities of Origen. Additional components relevant to this work include modernization of the reactor data libraries used by Origen for conducting nuclear fuel depletion calculations. This work has included the development of new fuel assembly lattices not previously available (such as for CANDU heavy-water reactor assemblies) as well as validation of updated lattices for light-water reactors updated to employ modern nuclear data evaluations. The CyBORG reactor analysis module as-developed under this workscope is fully capable of dynamic calculation of depleted fuel compositions from all commercial U.S. reactor assembly types as well as a number of international fuel types, including MOX, VVER, MAGNOX, and PHWR CANDU fuel assemblies. In addition, the Origen-based depletion engine allows for CyBORG to evaluate novel fuel assembly and reactor design types via creation of Origen reactor data libraries via SCALE. The establishment of this new modeling capability affords fuel cycle modelers a substantially improved ability to model dynamically-changing fuel cycle and reactor conditions, including recycled fuel compositions from fuel cycle scenarios involving material recycle into thermal-spectrum systems.

Full-Scale Cask Testing and Public Acceptance of Spent Nuclear Fuel Shipments - 12254

Energy Technology Data Exchange (ETDEWEB)

Dilger, Fred [Black Mountain Research, Henderson, NV 81012 (United States); Halstead, Robert J. [State of Nevada Agency for Nuclear Projects Carson City, NV 80906 (United States); Ballard, James D. [Department of Sociology, California State University, Northridge Northridge, CA 91330 (United States)

2012-07-01

Laboratories, the 1980's regulatory and demonstration testing of MAGNOX fuel flasks in the United Kingdom (the CEGB 'Operation Smash Hit' tests), and the 1980's regulatory drop and fire tests conducted on the TRUPACT II containers used for transuranic waste shipments to the Waste Isolation Pilot Plant in New Mexico. The primary focus of the paper is a detailed evaluation of the cask testing programs proposed by the NRC in its decision implementing staff recommendations based on the Package Performance Study, and by the State of Nevada recommendations based on previous work by Audin, Resnikoff, Dilger, Halstead, and Greiner. The NRC approach is based on demonstration impact testing (locomotive strike) of a large rail cask, either the TAD cask proposed by DOE for spent fuel shipments to Yucca Mountain, or a similar currently licensed dual-purpose cask. The NRC program might also be expanded to include fire testing of a legal-weight truck cask. The Nevada approach calls for a minimum of two tests: regulatory testing (impact, fire, puncture, immersion) of a rail cask, and extra-regulatory fire testing of a legal-weight truck cask, based on the cask performance modeling work by Greiner. The paper concludes with a discussion of key procedural elements - test costs and funding sources, development of testing protocols, selection of testing facilities, and test peer review - and various methods of communicating the test results to a broad range of stakeholder audiences. (authors)

VSOP, Neutron Spectra, 2-D Flux Synthesis, Fuel Management, Thermohydraulics Calculation

International Nuclear Information System (INIS)

Teuchert, E.; Haas, K.A.

1995-01-01

1 - Description of problem or function: VSOP (Very Superior Old Programs) is a system of codes linked together for the simulation of reactor life histories. It comprises neutron cross section libraries and processing routines, repeated neutron spectrum evaluation, 2-D and 3-D diffusion calculation, depletion and shut-down features, in- core and out-of-pile fuel management, fuel cycle cost analysis, and thermal hydraulics (steady state and transient). Various techniques have been employed to accelerate the iterative processes and to optimize the internal data transfer. The code system has been used extensively for comparison studies of thermal reactors, their fuel cycles, thermal transients, and safety assessment. Besides its use in research and development work for the Gas Cooled High Temperature Reactor, the system has been applied successfully to Light Water and Heavy Water Reactors, MAGNOX, and RBMK. 2 - Method of solution: The nuclear data for 184 isotopes are contained in two libraries. Fast and epithermal data in a 68 group GAM-I structure have been prepared mainly from ENDF/B-V and JEF-1. Resonance cross section data are given as input. Thermal data in a 30 group THERMOS structure have been collapsed from a 96 group THERMALIZATION (GATHER) library by a relevant neutron energy spectrum generated by the THERMALIZATION code. Graphite scattering matrices are based on the Young phonon spectrum in graphite. The neutron spectrum is calculated by a combination of the GAM and THERMOS codes. They can simultaneously be employed for many core regions differing in temperature, burnup, and fuel element lay-out. The thermal cell code THERMOS has been extended to treat the grain structure of the coated particles inside the fuel elements, and the epithermal GAM code uses modified cross sections for the resonance absorbers prepared from double heterogeneous ZUT-DGL calculations. The diffusion module of the code is CITATION with 2 - 8 energy groups. It provides the neutron

Isotope Specific Remediation Media and Systems - 13614

Energy Technology Data Exchange (ETDEWEB)

Denton, Mark S.; Mertz, Joshua L. [Kurion, Inc. Oak Ridge, Tennessee 37831 (United States); Morita, Keisuke [Japan Atomic Energy Agency, Tokai Research and Development Center, Fukushima Project Team, Tokai-mura, Ibaraki-ken, 319-1195 (Japan)

2013-07-01

Electric Power Company (TEPCO). The tests have proven quite successful, even in high salt conditions, and, with loading and dose calculations being completed, will be proposed to add to the existing cesium system. There is no doubt, as high gamma isotopes are removed, other recalcitrant isotopes such as this will require innovative removal media, systems and techniques. Also coming out of this international effort are other ISM media and systems that can be applied more broadly to both Commercial Nuclear Power Plants (NPPs) as well as in Department of Energy (DOE) applications. This cesium and strontium specific media has further been successfully tested in 2012 at a Magnox station in the UK. The resulting proposed mitigation systems for pond and vault cleanup look quite promising. An extremely unusual ISM for carbon 14 (C-14), nickel (Ni-63) and cesium (Cs-137) has been developed for Diablo Canyon NPP for dose reduction testing in their fuel pool. These media will be deployed in Submersible Media Filter (SMF) and Submersible Columns (SC) systems adapted to standard Tri-Nuclear{sup R} housings common in the U.S. and UK. External Vessel Systems (mini-Fukushima) have also been developed as a second mitigation system for D and D and outages. Finally, technetium (Tc- 99) specific media developed for the Waste Treatment Plant (WTP) recycle or condensate (secondary) waste streams (WM 2011) are being further perfected and tested for At-Tank Tc-99 removal, as well as At Tank Cs media. In addition to the on-going media development, systems for deploying such media have developed over the last year and are in laboratory- and full-scale testing. These systems include the fore mentioned Submersible Media Filters (SMF), Submersible Columns (SC) and external pilot- and full-scale, lead-lag, canister systems. This paper will include the media development and testing, as well as that of the deployment systems themselves. (authors)

Radioactivity in the environment. Report for 2001 : a summary and radiological assessment of the Environment Agency's monitoring programmes

International Nuclear Information System (INIS)

2003-01-01

their high occupancy over inter-tidal sediments that contain radionuclides discharged from both BNFL Sellafield and BNFL Springfields. On the Cumbria coast, annual doses were up to 37 μSv, similar to previous years. Elsewhere in England and Wales, annual doses arising from radionuclides in sediment or water were about 15 μSv or less. An assessment was also made of exposure to radionuclides in air discharged from Magnox nuclear power stations and from Sellafield. The doses ranged from 10 μSv/y near Oldbury to 85 μSv/y near Dungeness A. (author)

Innovative Highly Selective Removal of Cesium and Strontium Utilizing a Newly Developed Class of Inorganic Ion Specific Media - 16221

International Nuclear Information System (INIS)

Denton, Mark S.; Kanatzidis, Mercouri G.

2009-01-01

Highly selective removal of Cesium and Strontium is critical for waste treatment and environmental remediation. Cesium-137 is a beta-gamma emitter and Strontium-90 is a beta emitter with respective half-lives of 30 and 29 years. Both elements are present at many nuclear sites. Cesium and Strontium can be found in wastewaters at Washington State's Hanford Site, as well as in waste streams of many Magnox reactor sites. Cesium and Strontium are found in the Reactor Coolant System of light water reactors at nuclear power plants. Both elements are also found in spent nuclear fuel and in high-level waste (HLW) at DOE sites. Cesium and Strontium are further major contributors to the activity and the heat load. Therefore, technologies to extract Cesium and Strontium are critical for environmental remediation waste treatment and dose minimization. Radionuclides such as Cesium-137 and Strontium-90 are key drivers of liquid waste classification at light water reactors and within the DOE tank farm complexes. The treatment, storage, and disposal of these wastes represents a major cost for nuclear power plant operators, and comprises one of the most challenging technology-driven projects for the DOE Environmental Management (EM) program. Extraction technologies to remove Cesium and Strontium have been an active field of research. Four notable extraction technologies have been developed so far for HLW: solvent extraction, prussian blue, crystalline silico-titanate (CST) and organic ion-exchangers (e.g., resorcinol formaldehyde and SuperLig). The use of one technology over another depends on the specific application. For example, the waste treatment plant (WTP) at Hanford is planning on using a highly-selective organic ion-exchange resin to remove Cesium and Strontium. Such organic ion-exchangers use molecular recognition to selectively bind to Cesium and Strontium. However, these organic ion-exchangers are synthesized using multi-step organic synthesis. The associated cost to

Ion irradiation used as surrogate of neutron irradiation in graphite: Consequences on 14C and 36Cl behavior and structural evolution

Science.gov (United States)

Galy, N.; Toulhoat, N.; Moncoffre, N.; Pipon, Y.; Bérerd, N.; Ammar, M. R.; Simon, P.; Deldicque, D.; Sainsot, P.

2018-04-01

Graphite has been widely used as neutron moderator, reflector or fuel matrix in different types of reactors such as gas cooled nuclear reactors (UNGG, Magnox, AGR), RBMK reactors or high temperature gas cooled reactors. Their operation produces a great quantity of irradiated graphite or other carbonaceous waste (around 250,000 tons worldwide) that requires a special management strategy. In the case of disposal, which is a current management strategy, two main radionuclides, 14C and 36Cl might be dose determining at the outlet. Particular attention is paid to 14C due to its long half-life (T∼5730 years) [1] and as major contributor to the radioactive dose. 14C has two main production routes, i) transmutation of nitrogen (14N(n,p)14C) where nitrogen is mainly adsorbed at the surfaces of the irradiated graphite; ii) activation of carbon from the matrix (13C(n,γ)14C). According to leaching tests, it was shown that even if the quantity of 14C released in the solution is low (less than 1% of the initial inventory), around 30% is in the organic form that would be mobile in repository conditions [2,3]. 36Cl is mainly produced through the activation of 35Cl (35Cl(n,γ)36Cl) which is an impurity in nuclear graphite. Its activity is low but it might be highly mobile in clay host rocks. Thus, in order to make informed decisions about the best management process and to anticipate potential radionuclide dissemination during dismantling and in the repository, it is necessary to collect information on 14C and 36Cl location and speciation in graphite, after reactor closure. The goal of the present paper is therefore to use ion irradiation to simulate neutron irradiation and to evaluate the irradiation effects on the behavior of 36Cl and 14C as well as on the induced graphite structure modifications. For that, to understand and model the underlying mechanisms, we used an indirect approach based on 13C or 37Cl implantation to simulate the respective presence of 14C or 36Cl. These

Reactor Dosimetry State of the Art 2008

Science.gov (United States)

Voorbraak, Wim; Debarberis, Luigi; D'Hondt, Pierre; Wagemans, Jan

2009-08-01

Oral session 1: Retrospective dosimetry. Retrospective dosimetry of VVER 440 reactor pressure vessel at the 3rd unit of Dukovany NPP / M. Marek ... [et al.]. Retrospective dosimetry study at the RPV of NPP Greifswald unit 1 / J. Konheiser ... [et al.]. Test of prototype detector for retrospective neutron dosimetry of reactor internals and vessel / K. Hayashi ... [et al.]. Neutron doses to the concrete vessel and tendons of a magnox reactor using retrospective dosimetry / D. A. Allen ... [et al.]. A retrospective dosimetry feasibility study for Atucha I / J. Wagemans ... [et al.]. Retrospective reactor dosimetry with zirconium alloy samples in a PWR / L. R. Greenwood and J. P. Foster -- Oral session 2: Experimental techniques. Characterizing the Time-dependent components of reactor n/y environments / P. J. Griffin, S. M. Luker and A. J. Suo-Anttila. Measurements of the recoil-ion response of silicon carbide detectors to fast neutrons / F. H. Ruddy, J. G. Seidel and F. Franceschini. Measurement of the neutron spectrum of the HB-4 cold source at the high flux isotope reactor at Oak Ridge National Laboratory / J. L. Robertson and E. B. Iverson. Feasibility of cavity ring-down laser spectroscopy for dose rate monitoring on nuclear reactor / H. Tomita ... [et al.]. Measuring transistor damage factors in a non-stable defect environment / D. B. King ... [et al.]. Neutron-detection based monitoring of void effects in boiling water reactors / J. Loberg ... [et al.] -- Poster session 1: Power reactor surveillance, retrospective dosimetry, benchmarks and inter-comparisons, adjustment methods, experimental techniques, transport calculations. Improved diagnostics for analysis of a reactor pulse radiation environment / S. M. Luker ... [et al.]. Simulation of the response of silicon carbide fast neutron detectors / F. Franceschini, F. H. Ruddy and B. Petrović. NSV A-3: a computer code for least-squares adjustment of neutron spectra and measured dosimeter responses / J. G