United Kingdom Atomic Energy Authority Research Articles

Fusion decommissioning and regulation (UK-STEP perspectives)

A Funded Decommissioning Programme (FDP) is submitted to the secretary of state for approval as a requirement for a nuclear site licensee to install or operate a nuclear power station. The United Kingdom Atomic Energy Authority (UKAEA) Spherical Tokamak for Energy Production (STEP) reactor will not require a nuclear site licence and therefore a FDP is currently not a legal requirement under Section 45 of the Energy Act 2008, (HMG 2008 Energy act 2008). However, it is expected that in line with the UK energy sector the UKAEA STEP programme needs to understand what is required both technically and financially to decommission the STEP reactor and associated facilities. This considers the initial summary level documents to support the FDP, which sets out the steps to decommission STEP at the end of its operational life. These documents are not fully developed as the STEP programme is currently in the concept design stage and is expected to be revised as more information becomes available and the Funding Arrangements Plan (FAP) and Decommissioning and Waste Management Plan (DWMP) are developed further along with the Detailed DWMP (DDWMP) which underpins the DWMP is also developed. Ultimately the DWMP, DDWMP and references should demonstrate UKAEA’s plans for the decommissioning of the West Burton site and for the management and disposal of waste 3 3Waste in this paper includes both primary and secondary waste arisings. arisings are realistic, clearly defined and achievable. Although this work has been done within the context of the UK and for a spherical tokamak a lot of the designated technical matters and technical matter that are not designated will be applicable to decommissioning outside of the UK as the work for decommissioning is still required, irrespective of the legal framework for funding of the decommissioning. This work is also applicable for other forms of fusion devices, especially as they develop into commercial scale for energy production, as the drivers are associated with the hazards from ionising radiation.

Detritiation of JET Beryllium and Tungsten

During the operation of a fusion reactor, first wall components are exposed to the plasma and therefore tritium, resulting in generation of tritiated materials that would be classified as intermediate level waste (ILW) following their removal from the vessel. Investigations were undertaken into the thermal treatment of beryllium and tungsten representative of the materials used within the Joint European Torus (JET) fusion reactor to assess if tritium from these materials can be removed in the Material Detritiation Facility at the United Kingdom Atomic Energy Authority. This detritiation process may allow the reclassification of these materials as low level waste (LLW). When heated in the presence of oxygen, both tungsten and beryllium readily oxidize as temperature increases. The oxide layers that are formed on tungsten and beryllium surfaces are thought to act as a tritium barrier, reducing the amount of tritium that can be removed by thermal treatment. As such, the generation of oxide layers may need to be minimized for treatment of tungsten and beryllium, potentially via thermal treatment at lower temperatures. Additionally, the formation of beryllium oxide presents health and safety concerns due to its toxicity and physical form. Experiments were undertaken using tungsten and beryllium samples from previous JET campaigns. The samples were heated in a pyrolyzer, and the tritium released was captured in a series of bubblers. The remaining tritium in the material was characterized by acid dissolution to allow for detritiation factors (which are defined as the fraction of tritium inventory in the sample before and after the thermal treatment) to be calculated. Tritium was successfully removed from the samples by thermal treatment in air. Future trials will use samples with larger tritium inventory to confirm obtained results and demonstrate the feasibility of thermal treatment as a detritiation method for tungsten and beryllium on higher-activity samples. This should allow for samples representative of the JET ITER-like wall (current JET configuration) to be detritiated and could demonstrate the ability of the process to reduce the tritium inventory of JET materials and allow reclassification of components from ILW to LLW.

Advancing Methods for Fusion Neutronics: An Overview of Workflows and Nuclear Analysis Activities at UKAEA

Global research programs seeking to achieve a commercially viable model of a fusion power plant are being accelerated at an unprecedented rate. One critical element to the design and licensing is an accurate understanding of the radiation environment throughout the plant lifetime and subsequent decommissioning phase. The radiation field, which results from the nuclear fusion reaction, gives rise to highly complex phenomena such as flux leakage, materials activation, and decay gamma fields. Demonstration of compliance with limits, the integrity of components, and the permissibility of operations are all fundamental to regulatory approval and the overall safety of a nuclear device. As such, neutronics, which is used in the general sense to refer to the mapping of radiation fields in nuclear devices, is a critical design driver. The Applied Radiation Technology group at the United Kingdom Atomic Energy Authority is a world leader in this field, developing new methods and deploying state-of-the-art codes to conduct nuclear analysis. As well as applied neutronics in areas spanning fusion reactors, medical applications, spallation neutron sources, and nuclear fission, there is an extensive parallel experimental program undertaking critical radiation field characterization and conducting measurements using an array of bespoke particle detection systems. This paper highlights recent technical developments made by this group in the context of outstanding challenges in this field, as well as providing an overview of current methods and capabilities for the broader interest of the community.

Film and the British Atomic Project

This essay explores the process through which the moving image became part of the promotion of Britain as a new nuclear nation in the mid-1950s. Made by, for, or with the authority of the newly created United Kingdom Atomic Energy Authority, a number of films were produced by different companies, all presenting the UKAEA as a modern, national asset, justifying its development of both military and civil uses of atomic energy together. There was no sophisticated studio for this purpose to match Lookout Mountain and the role it played in the US military development of atomic weapons. Instead the Central Office of Information Films Division and the documentary production companies it employed used the skills and resources still in existence after the heyday of the British documentary movement to document and represent a new important reality.

Dounreay: Creating the Nuclear North

This article combines the traditionally rural focus of Highland history with the growing field of nuclear culture to examine the impact which Dounreay Experimental Research Establishment had on Caithness between 1953 and 1966. From the outset of the project the United Kingdom Atomic Energy Authority knew that it would have to import specialist technical staff into an area economically driven by agriculture and fishing. This resulted in a distinct form of employment-based migration to the Highlands, reversing population decline in Caithness during the period of study. This article identifies the reasons for, and local reaction to, the UKAEA's choice of Caithness as the location for its fast breeder reactor establishment. It assesses the significant in-migration to the area during the initial phase of the Dounreay plant's development, before exploring how perceptions of distance and Caithnessian ‘difference’ affected the recruitment of staff in what the UKAEA considered an ‘unconventional’ location. It puts people and place at the centre of the nuclear project, revealing Dounreay's role in creating a mid-twentieth century Highland counter-narrative of in-migration and modernity far removed from traditional discourses of depopulation.

Characterization of radioactive particles from the Dounreay nuclear reprocessing facility

Radioactive particles originating from nuclear fuel reprocessing at the United Kingdom Atomic Energy Authority's Dounreay Facility were inadvertently released to the environment in the late 1950s to 1970s and have subsequently been found on site grounds and local beaches. Previous assessments of risk associated with encountering a particle have been based on conservative assumptions related to particle composition and speciation. To reduce uncertainties associated with environmental impact assessments from Dounreay particles, further characterization is relevant.Results of particles available for this study showed variation between Dounreay Fast Reactor (DFR) and Materials Test Reactor (MTR) particles, reflecting differences in fuel design, release scenarios, and subsequent environmental influence. Analyses of DFR particles showed they are small (100–300 μm) and contain spatially correlated U and Nb. Molybdenum, part of the DFR fuel, was identified at atomic concentrations below 1%. Based on SR-based micrometer-scale X-ray Absorption Near Edge Structure spectroscopy (μ-XANES), U may be present as U(IV), and, based on a measured Nb/U atom ratio of ~2, stoichiometric considerations are commensurable with the presence of UNb2O7. The MTR particles were larger (740–2000 μm) and contained U and Al inhomogeneously distributed. Neodymium (Nd) was identified in atomic concentrations of around 1–2%, suggesting it was part of the fuel design. The presence of U(IV) in MTR particles, as indicated by μ-XANES analysis, may be related to oxidation of particle surfaces, as could be expected due to corrosion of UAlx fuel particles in air. High 235U/238U atom ratios in individual DFR (3.2 ± 0.8) and MTR (2.6 ± 0.4) particles reflected the presence of highly enriched uranium. The DFR particles featured lower 137Cs activity levels (2.00–9.58 kBq/particle) than the MTR (43.2–641 kBq 137Cs/particle) particles. The activities of the dose contributing radionuclides 90Sr/90Y were proportional to 137Cs (90Sr/137Cs activity ratio ≈ 0.8) and particle activities were roughly proportional to the size. Based on direct beta measurements, gamma spectrometry, and the VARSKIN6 model, contact dose rates were calculated to be approximately 74 mGy/h for the highest activity MTR particle, in agreement with previously published estimates.

Report on the accident at Windscale No. 1 Pile on 10 October 1957**Reproduction of the Report (the ‘Penney Report’) of the Committee of Inquiry (Chairman, Sir William Penney) established by the United Kingdom Atomic Energy Authority (UKAEA), which reported to the UKAEA on 26 October, 1957. The Report was made public in January, 1988, and the original can be found

A serious fire developed in the core of a nuclear reactor at Windscale Works, Sellafield, northwest England, which led to the release of significant quantities of radioactive material into the environment during 10–11th October, 1957. In 1957, Windscale Works was operated by the United Kingdom Atomic Energy Authority (UKAEA), and on 15th October it was announced by the Chairman of the UKAEA that a Committee of Inquiry had been established under the chairmanship of Sir William Penney to conduct an investigation into the accident. The Committee sat at Windscale Works during 17–25th October, interviewed 37 people (some more than once), and examined 73 technical exhibits. The Committee reported to the Chairman of the UKAEA on 26th October. The Report of the Committee formed the technical basis of a UK Government White Paper (Cmnd. 302) published on 8th November, 1957, but the Penney Report itself was not published, and was only made public (at what is now The National Archives, TNA, Kew) in January, 1988. The original Report of the Committee of Inquiry is reproduced here from a copy of the Report supplied by TNA from TNA File AB 86/25.

The Diamond Light Source.

This Current Commentary was prompted by a recent talk given by Laura Holland, at Reading Skeptics in the Pub, about the Diamond Light Source, where she is the Outreach and Events Manager. Skeptics in the Pub (1) is a growing, informal network of (usually) monthly meetings, where the invited speaker presents a topic of interest in a pub, which is followed by a discussion. A broad range of subjects is aired, covering various aspects of science and technology, and such diverse matters as philosophy, homeopathy, the media, education, electric cars, GM crops, the paranormal, and depletion of the Earth's resources (which I have spoken about to various Skeptics groups). Skeptics in some respects resembles Cafe Scientifique, although the latter meetings (2) tend to be more particularly focussed on features of science and technology. Diamond (3) (Figure 1) is the UK's national synchrotron science facility, and is situated on the Harwell campus in Oxfordshire, which also houses the Rutherford Appleton Laboratory. The campus is owned by the United Kingdom Atomic Energy Authority (UKAEA), the Science and Technology Facilities Council and the Health Protection Agency. It is managed by Harwell Oxford Developments Ltd. The Diamond synchrotron can produce intense beams of light, said (3) to be 10 billion times brighter than the sun. Here, the term does not only refer to the region of the electromagnetic spectrum that is visible to humans (namely wavelengths in the 400-700 nm range), since Diamond generates synchrotron light, which is a spectrum of electromagnetic radiation spanning X-rays to microwaves. The UK led the world with the first second-generation light source, the SRS at the Daresbury Laboratory in Cheshire, which opened in 1981. The SRS proved how vital synchrotrons are to researchers from a wide range of disciplines and, when it had expanded as much as it could, scientists and engineers began designing a third generation synchrotron for the UK. Diamond is the largest scientific facility to be built in the UK, since the Nimrod proton synchrotron at the Rutherford Appleton laboratory (RAL) in 1964. Nimrod was converted into the (ISIS) neutron spallation source in 1977. ISIS is not an acronym, but is both the name by which the River Thames is known locally, and a goddess of Ancient Egypt who could restore life to the dead: this seemed appropriate since the ISIS facility was partially constructed from cannibalised equipment from the Nimrod and NINA accelerators. [FIGURE 1 OMITTED] In contrast, DIAMOND is an acronym: Dipole And Multipole Output for the Nation at Daresbury, as derived by Mike Poole, who inaugurated the DIAMOND project. Since the facility is no longer at Daresbury, it is said that the name now reflects the fact that the synchrotron light is both 'hard' (as in the hard X-ray region of the electromagnetic spectrum) and bright, similar to those qualities of a diamond. The Diamond facility cost an initial 260 m [pounds sterling] to build, including the synchrotron building, the accelerators, the first seven beamlines and the adjacent office block, Diamond House. 86% of Diamond's funding comes from the Science and Technology Facilities Council (STFC) and 14% from the Wellcome Trust. More than 3,000 research workers carry out experiments using synchrotron radiation at Diamond, and are assisted by some 500 permanent staff there. Features of synchrotron radiation 1. A wide energy-range of the electromagnetic spectrum, spanning X-rays to microwaves. 2. The very intense beam of photons means that crystals that scatter radiation only weakly may be studied, and experiments can be done rapidly. 3. Due to a small divergence and small size source (spatial coherence), a highly collimated beam is obtained. 4. A source stability is obtained at the sub-micron level. 5. Both linear and circular polarisation are possible. 6. …

Seismic Evaluation of a Multipurpose Tower in Yellowknife, Northwest Territories, Canada

Locating scientific instruments in remote regions of the planet poses many common problems beyond just logistics, in particular when these instruments are to function autonomously or semiautonomously. In seismology, this is particularly prevalent for seismic stations located in the polar regions of the planet. Extremely cold, but also variable temperature, wind, and sunlight conditions as well as general inaccessibility hamper both operation and maintenance of equipment in such regions (Gill, 1974; Holcomb, 1982). The search for a reliable source of electrical power for the continuous operation of sensors and digitizing equipment continues to be one of these concerns. Many technologies have been investigated including radioisotope thermoelectric generation (e.g., Lamp, 1994), thermal electric generators (TEGs) (e.g., Holcomb, 1982), diesel engines, chemical batteries, wind and solar power generation (Anandakrishnan et al. , 2000), and more recently, fuel‐cell technology (e.g., Stehle et al. , 2011). Each technology has its own pros and cons, and in general, the technology that is chosen is based on which best suits the application, its requirements, and stresses of the station and its operators. For seismic instruments, this often requires that any noise generated by this choice does not adversely affect the operation or observations of ground motion the instrument is trying to measure. Such is the case at the Yellowknife teleseismic array in Canada’s Northwest Territories. Commissioned in 1962, the role of the Yellowknife seismic array (YKA) was to investigate the capabilities of distributed arrays of seismometers to monitor for the tell‐tale ground motions from explosions of nuclear weapons testing by the then nuclear‐capable countries of the United States, Great Britain, France, and the former Soviet Union. In one of the eventually five similar arrays constructed by the United Kingdom Atomic Energy Authority (UKAEA), the research was to determine if small numbers of seismic arrays could be …

Uncertainties on Lung Doses from Inhaled Plutonium

In a recent epidemiological study, Bayesian uncertainties on lung doses have been calculated to determine lung cancer risk from occupational exposures to plutonium. These calculations used a revised version of the Human Respiratory Tract Model (HRTM) published by the ICRP. In addition to the Bayesian analyses, which give probability distributions of doses, point estimates of doses (single estimates without uncertainty) were also provided for that study using the existing HRTM as it is described in ICRP Publication 66; these are to be used in a preliminary analysis of risk. To infer the differences between the point estimates and Bayesian uncertainty analyses, this paper applies the methodology to former workers of the United Kingdom Atomic Energy Authority (UKAEA), who constituted a subset of the study cohort. The resulting probability distributions of lung doses are compared with the point estimates obtained for each worker. It is shown that mean posterior lung doses are around two- to fourfold higher than point estimates and that uncertainties on doses vary over a wide range, greater than two orders of magnitude for some lung tissues. In addition, we demonstrate that uncertainties on the parameter values, rather than the model structure, are largely responsible for these effects. Of these it appears to be the parameters describing absorption from the lungs to blood that have the greatest impact on estimates of lung doses from urine bioassay. Therefore, accurate determination of the chemical form of inhaled plutonium and the absorption parameter values for these materials is important for obtaining reliable estimates of lung doses and hence risk from occupational exposures to plutonium.

Design and licensing of UKAEA IP 2m box

Abstract Croft Associates Ltd (Croft) was contracted by the United Kingdom Atomic Energy Authority (UKAEA), Winfrith in 2006 to design, manufacture, test and license an intermediate level waste industrial package transport packaging (UKAEA 2 m Box Design no. 3954) for decommissioning waste from the Dragon and steam generating heavy water reactors at Winfrith. The package had to meet the requirements of the existing UK. Nuclear Decommissioning Authority (NDA) (Nirex) 2 m Box specification. The UKAEA 2 m Box is intended for on-site storage at Winfrith and possibly another site for 50 years and subsequent transport to the NDA repository without further processing. The design of the box closure includes a leak testable sealing system which is capable of being replaced at a later date (e.g. before shipment), by the removal of the lid and replacement of seals remote from the box location. Initially the specification for the UKAEA 2 m Box called for rating for gross weight of 40 t, but this was raised to 50 t as...

Project WAGR: the UK Demonstration Project for Power Reactor Decommissioning

The United Kingdom Atomic Energy Authority (UKAEA) has built and operated a wide range of nuclear facilities since the late 1940’s. UKAEA’s mission is to restore the environment of its sites in a safe and secure manner. This restoration includes the decommissioning of a number of redundant research and power reactors.The Windscale Advanced Gas-cooled Reactor (WAGR) was the UK’s prototype Advanced gas cooled reactor and became the forerunner of a family of 14 reactors built to generate cheaper and more efficient electricity in the UK. WAGR was constructed between 1957 and 1961 and was a carbon dioxide cooled, graphite moderated reactor using uranium oxide fuel in stainless steel cans. The reactor consisted of a graphite moderator housed in a cylindrical reactor vessel with hemispherical ends. The reactor and associated heat exchangers were enclosed in the iconic spherical containment building regularly used by the media in the UK as an illustration of the nuclear industry.The reactor first produced power in August 1962 and achieved full design output in 1963. It operated at an electrical output of 33 MW (E) for 18 years (average load factor of 75%). In 1981 the reactor was shut down after satisfactory completion of all the research and development objectives.In anticipation of the UK’s likely nuclear decommissioning needs the UKAEA decided to decommission WAGR to the International Atomic Energy Agency’s (IAEA) stage 3 (restoration of the area occupied by the facility to a condition of unrestricted re-usability) as the national demonstration exercise for power reactor decommissioning.Since 1998 the UKAEA and its contractors have been undertaking the dismantling of the reactor core components and pressure vessel in a series of 10 campaigns. These contain neutron activated components expected to produce dose rates well in excess of 1Sv/hr. To carry out the work UKAEA installed an £8M remote dismantling machine (RDM), a waste recovery and transport system and a shielded waste route through which to move, sort, assay condition and package the waste. The RDM and associated hoist have been used to deploy the numerous tools and end effectors necessary to effect the painstaking dismantling process.Now that the remote operations are reaching a conclusion it is possible to review the success of both these tools and the RDM itself.

Detritiation studies for JET decommissioning

JET is the world's largest tokamak and has operated with tritium plasma. In the Deuterium-Tritium Experiment (DTE1) about 30% of tritium fed to the tokamak was retained in the vessel and in-vessel components. It is expected that in a several years time JET will cease experimental operations and enter a decommissioning phase. In situ detritiation of the vacuum vessel is likely to be needed prior to its dismantling. To reduce cost of subsequent storage and disposal, post-dismantling detritiation of components and waste will be needed. The United Kingdom Atomic Energy Authority, which operates the JET machine, has been carrying out studies of various detritiation techniques in order to select and experimentally prove technologies for in situ and ex situ detritiation of potential waste. This paper summarises the results.

Experience in Progressing the Planning Application for New LLW Disposal Facilities for Dounreay

AbstractAn integral part of decommissioning the Nuclear Decommissioning Agency's (NDA) Dounreay site is the management of the solid low level radioactive waste (LLW). The United Kingdom Atomic Energy Authority (UKAEA) has developed and progressed a technical and stakeholder programme that has enabled it to submit a robust Planning Application to Highland Council (HC) for New LLW Disposal Facilities at Dounreay and to submit substantive preliminary safety and environmental cases to the Nuclear Installations Inspectorate (NII) and the Scottish Environment Protection Agency (SEPA). To UKAEA’s knowledge this is the most advanced project in the UK for new LLW disposal facilities. Experience has been gained in progressing the Best Practicable Environmental Option (BPEO) Study, working with regulators in unfamiliar areas, and undertaking groundbreaking stakeholder consultation. Key lessons learnt are that stakeholders should be engaged in dialogue on the project as early as possible, documentation must be high quality and tailored to its audience, and internationally respected and credible consultants must be involved.

Determining a strategy for managing radioactive particles in the environment: establishingthe BPEO**This paper has been revised following evolution of the BPEO process.

The United Kingdom Atomic Energy Authority (UKAEA) is in the process ofidentifying the long-term management strategy for radioactive particles in theenvironment. Application of the standard best practicable environmental option (BPEO)methodology to this issue is, however, complicated because particles reside in both theon-shore and off-shore environments. Methods for implementation of potentialmanagement options may vary due to the differing characteristics of the on- and off-shoreenvironments. A different management option may therefore be required, andfurthermore the dynamic interaction between these two environments influences howthese options could be combined to provide an overall management strategy.UKAEA has developed the standard BPEO appraisal process so that distinct managementoptions for both environments are initially assessed separately. This allows identification ofthe key issues that influence how they are combined into an overall management strategy.Over the last two years the public consultation on this issue has progressed substantiallyand therefore the paper presented at the Nairn conference in 2005 has been revised to takeinto account the work carried out to date.

Rendel Sebastian Pease

Rendel Sebastian Pease

Decommissioning of a liquid effluent treatment R&D facility

The United Kingdom Atomic Energy Authority (UKAEA) is responsible for managing the decommissioning of the nuclear reactors and other radioactive facilities used for the UKAEA nuclear research and development programme in a safe and environmentally responsible manner with the objective of restoring the sites for conventional use. It is also responsible for input to the European fusion research programme and for maximizing the income from the land and buildings at its sites at Dounreay in Scotland, Windscale in Cumbria, Harwell and Culham in Oxfordshire and Winfrith in Dorset. Building 336.28 typified the problems encountered during the removal of redundant facilities from the liquid effluent treatment plant at Harwell. The building was constructed in the late 1940s, was lined with asbestos limpet and contained a range of poorly characterized liabilities that had been ‘mothballed’ after use. Decommissioning was carried out following competitive tender. The work involved the removal of radioactive liquids and wastes, the dismantling and removal of contaminated tanks, vessels, glove boxes and test rigs and the demolition of the building. There were uncertainties associated with the radioactive inventory, the extent of the contamination beneath the floor slab and the processing requirements for the waste ion-exchange resins. These were addressed by a combination of characterization surveys (carried out by UKAEA at the pre-tender stage) and the use of unit work rates within the contract for some activities. In addition, the flexible approach by both the client (UKAEA) and the implementation contractor (NNC Limited) enabled the project end-point to be redefined to manage the widespread low-level contamination discovered beneath the floor slab.

Mortality of employees of the United Kingdom Atomic Energy Authority, 1946–97

Background: The workforce of the UK Atomic Energy Authority has been the subject of several previous epidemiological investigations. Aims: To detect and investigate associations between mortality rates and employment in...

Detection of radioactive particles offshore by γ-ray spectrometry Part I: Monte Carlo assessment of detection depth limits

A joint research project between the British Geological Survey and Nuclear Geophysics Division of the Kernfysisch Versneller Instituut, Groningen, the Netherlands, was commissioned by the United Kingdom Atomic Energy Authority to establish the efficiency of a towed seabed γ-ray spectrometer for the detection of 137 Cs -containing radioactive particles offshore Dounreay, Scotland. Using the MCNP code, a comprehensive Monte Carlo feasibility study was carried out to model various combinations of geological matrices, particle burial depth and lateral displacement, source activity and detector material. To validate the sampling and absolute normalisation procedures of MCNP for geometries including multiple (natural and induced) heterogeneous sources in environmental monitoring, a benchmark experiment was conducted. The study demonstrates the ability of seabed γ-ray spectrometry to locate radioactive particles offshore and to distinguish between γ count rate increases due to particles from those due to enhanced natural radioactivity. The information presented in this study will be beneficial for estimation of the inventory of 137 Cs particles and their activity distribution and for the recovery of particles from the sea floor. In this paper, the Monte Carlo assessment of the detection limits is presented. The estimation of the required towing speed and acquisition times and their application to radioactive particle detection and discrimination offshore formed a supplementary part of this study.

Decontamination and waste minimisation techniques in nuclear decommissioning

Decommissioning of redundant nuclear facilities requires judicious use of decontamination either to reduce the radiation levels or to minimise the volume of radioactive waste produced when a facility is dismantled. A range of decontamination techniques is available, such as scabbling or pressure-jet washing. The choice of technique depends on individual circumstances. This paper describes the pros and cons of various decontamination techniques which are available, giving examples from a number of successfully completed United Kingdom Atomic Energy Authority projects. It also considers instances of novel applications where such practices have not been so successful and the lessons that have been learned.