Radioactive Waste Inventory Research Articles

Microbial degradation of isosaccharinic acid at high pH.

Intermediate-level radioactive waste (ILW), which dominates the radioactive waste inventory in the United Kingdom on a volumetric basis, is proposed to be disposed of via a multibarrier deep geological disposal facility (GDF). ILW is a heterogeneous wasteform that contains substantial amounts of cellulosic material encased in concrete. Upon resaturation of the facility with groundwater, alkali conditions will dominate and will lead to the chemical degradation of cellulose, producing a substantial amount of organic co-contaminants, particularly isosaccharinic acid (ISA). ISA can form soluble complexes with radionuclides, thereby mobilising them and posing a potential threat to the surrounding environment or ‘far field'. Alkaliphilic microorganisms sampled from a legacy lime working site, which is an analogue for an ILW-GDF, were able to degrade ISA and couple this degradation to the reduction of electron acceptors that will dominate as the GDF progresses from an aerobic ‘open phase' through nitrate- and Fe(III)-reducing conditions post closure. Furthermore, pyrosequencing analyses showed that bacterial diversity declined as the reduction potential of the electron acceptor decreased and that more specialised organisms dominated under anaerobic conditions. These results imply that the microbial attenuation of ISA and comparable organic complexants, initially present or formed in situ, may play a role in reducing the mobility of radionuclides from an ILW-GDF, facilitating the reduction of undue pessimism in the long-term performance assessment of such facilities.

Simulation of repository gas migration in a bentonite buffer

The inventory of high-level radioactive waste in the UK is likely to be disposed of in a geological disposal facility, which will generate gases due to processes such as anoxic metal corrosion and water radiolysis. Such gases have the potential to migrate through the repository system and may be detrimental to the engineered barrier system by damaging the physical fabric of the buffer material through the build-up of pressure. An investigation into the migration of gases and the ranges of gas pressures expected in such a repository is presented. A model of gas transport is presented to simulate the transport of gases in conjunction with coupled thermo-hydro-chemical-mechanical processes. This model includes a boundary condition linking the corrosion behaviour to gas generation and water supply. A realistic range of gas generation rates has been established from available data alongside realistic ranges of material properties of a bentonite buffer. Numerical simulations were then undertaken for a range of realistic scenarios considering the corrosion processes and buffer properties. It was found that in all realistic cases, including realistic maxima and minima considered, the risk of pneumatic fracture was negligible.

Advances in the conceptual design of a gas-cooled Accelerator Driven System (ADS) transmutation device for a sustainable nuclear energy development

The possibilities of a nuclear energy development are considerably increasing with the world energetic demand increment. However, the management of nuclear waste from conventional nuclear power plants and its inventory minimization are the most important issues that should be addressed. Fast reactors and Accelerator Driven Systems (ADS) are the main options to reduce the long-lived radioactive waste inventory. Pebble Bed Very High Temperature advanced systems have great perspectives to assume the future nuclear energy development challenges. The conceptual design of a Transmutation Advanced Device for Sustainable Energy Applications (TADSEA) has been done in preliminary studies. The TADSEA is an ADS cooled by helium and moderated by graphite that uses as fuel small amounts of transuranic elements in the form of TRISO particles, confined in 3 cm radius graphite pebbles forming a pebble bed configuration. It would be used for nuclear waste transmutation and energy production. In the paper, the results of a method for calculating the number of whole pebbles fitting in a volume according to its size are showed. From these results, the packing fraction influence on the TADSEAs main work parameters is studied. In addition, a redesign of the previous configuration, according to the established conditions in the preliminary design, i.e. the exit thermal power, is made.Additionally, the heterogeneity of the TRISO particles inside the pebbles is not negligible. In the paper, a study of the power density distribution inside the pebbles using a detailed model of the TRISO particles and a homogeneous composition of the fuel is addressed.

Radioactive waste management in Italy

After a short review of radioactive waste origins and inventories in Italy, the paper deals with the current major challenges that Italy has to cope with to pursue its radioactive waste sustainable management and safe disposal. Site restoration by Sogin of dismissed nuclear installations is part of the waste management challenge. The importance of assuring the highest levels of safety culture among the employees and an overall manpower, adequate both in number and qualification according to the best international good practices, is underlined and included in the largest effort of the knowledge management project. Sogin is coping with the above challenges also with the Italian School on Radioprotection, Safety and Environment, a unique centre of know-how and know-why transfer in Italy.

Intended long term performances of cementitious engineered barriers for future storage and disposal facilities for radioactive wastes in Romania

Considering the EU statements, Romania is engaged to endorse in the near future the IAEA relevant publications on geological repository (CNCAN a ), to update the Medium and Long Term National Strategy for Safe Management of Radioactive Waste and to approve the Road Map for Geological Repository Development. Currently, for example, spent fuel is wet stored for 6 years and after this period it is transported to dry storage in MACSTOR-200 (a concrete monolithic module) where it is intended to remain at least 50 years. The present situation for radioactive waste management in Romania is reviewed in the present paper. Focus will be done on existent disposal facilities but, also, on future facilities planned for storage / disposal of radioactive wastes. Considering specific data for Romanian radioactive waste inventory, authors are reviewing the advance in the radioactive waste management in Romania considering its particularities. The team tries to highlight the expected limitations and unknown data related with cementitious engineered barriers that has to be faced in the near future in case of interim storage or for the upcoming long periods of disposal.

ACSEPT – Status in Advanced Separation Process Developments in Europe

Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste and to optimize the use of natural resources. With its multidisciplinary consortium of 34 partners from 12 European countries plus Australia and Japan, the European Research Project ACSEPT (Actinide reCycling by SEParation and Transmutation) aims at contributing to the development of this strategy by studying both hydrometallurgical and pyrochemical partitioning routes.After three years of work, significant progresses were achieved in process development with the demonstration of the SANEX and innovative SANEX flowsheets. Chemical systems were selected for GANEX and a demonstration flowsheet in under finalization. These results were achieved thanks to a strong involvement and reactivity of the consortium members. After about fifteen years of exploratory research on new extracting molecules, the work focuses now on the optimisation of the selected systems, particularly on some hydrophilic molecules or masking agents for specific fission products. Aside, the dissolution studies are now on the tracks.In pyrometallurgy, the work progresses as well. Headsteps studies gave promising results and two methods were developed for the back extraction of the actinides from the aluminium, wich is the metallic solvent involved in the two ACSEPT pyro processes.In addition, efforts were made to increase collaborations, mutualise and homogenise procedures and share good practices. Based on these assessments, it is then time to look at the future challenges to be issued.A training and education program is implemented to share the knowledge among the partitioning community, and present and future generations of researchers. Specific attention is also given to the funding of postdoctorate fellowships, and student exchanges between Partners. Through this training and education programme, the first ACSEPT International Workshop was organised in March 2010 in Lisbon, Portugal. This T&E program is a key point for maintaining a high expertise level in actinide separation sciences in Europe.The following of ACSEPT is currently under preparation to go further towards demonstration at the pilot scale.

ACSEPT—Partitioning technologies and actinide science: Towards pilot facilities in Europe

Actinide recycling by separation and transmutation is considered worldwide and particularly in several European countries as one of the most promising strategies to reduce the inventory of radioactive waste and to optimise the use of natural resources. With its multidisciplinary consortium of 34 partners from 12 European countries plus Australia and Japan, the European Research Project ACSEPT (Actinide reCycling by SEParation and Transmutation) aims at contributing to the development of this strategy by studying both hydrometallurgical and pyrochemical partitioning routes. ACSEPT is organised into three technical domains: (i) Considering technically mature aqueous separation processes, ACSEPT works to optimise and select the most promising ones dedicated either to actinide partitioning (for the heterogeneous recycling of actinides in ADS target or specific actinide bearing blanket fuels in fast reactor) or to grouped actinide separation (for the homogeneous recycling of the actinides in fast reactor fuels). In addition, dissolution and conversion studies are underway taking into account the specific requirements of these specific fuels. (ii) Concerning pyrochemical separation processes, ACSEPT focuses on the enhancement of the two reference cores processes selected within FP6-EUROPART. R&D efforts are also devoted to key scientific and technical issues compulsory to set up a complete separation process (head-end steps, salt treatment for recycling and waste management). (iii) By integrating all the experimental results in engineering and system studies, both in hydro and pyro domains, ACSEPT will deliver relevant flowsheets and recommendations to prepare for future demonstrations at a pilot level. After more than two years of work, significant progress was achieved in process development with the demonstration of the SANEX and innovative SANEX flowsheets. Chemical systems were selected for GANEX and are under study. In addition, efforts were made to increase collaborations, mutualise and homogenise procedures and share good practices. Based on these assessments, it is now time to look at the future challenges to overcome. A training and education program is implemented to share the knowledge among the partitioning community, present and future generations of researchers. Specific attention is paid to the funding of post-doctorate fellowships, two having been appointed respectively at the end of 2008 and at the end of 2009. Through this training and education programme, the first ACSEPT International Workshop was organised last March in Lisbon, Portugal. It gave an emphasis to young researchers’ contributions (two thirds of the contributions) and allowed young scientists to meet and exchange with international recognised experts.

Role of ADS in the back-end of the fuel cycle strategies and associated design activities: The case of Japan

Reduction of burden caused by radioactive waste management is one of the most critical issues for the sustainable utilization of nuclear power. The Partitioning and Transmutation (P&T) technology provides the possibility to reduce the amount of the radiotoxic inventory of the high-level radioactive waste (HLW) dramatically and to extend the repository capacity. The accelerator-driven system (ADS) is regarded as a powerful tool to effectively transmute minor actinides (MAs) in the “double-strata” fuel cycle strategy. The ADS has a potential to flexibly manage MA in the transient phase from light water reactors (LWRs) to fast breeder reactors (FBRs), and can co-exist with FBR symbiotically and complementarily to enhance the reliability and the safety of the commercial FBR cycle. The concept of ADS in JAEA is a lead–bismuth eutectic (LBE) cooled, tank-type subcritical reactor with the power of 800 MWth driven by a 30 MW superconducting LINAC. By such an ADS, 250 kg of MA can be transmuted annually, which corresponds to the amount of MA produced in 10 units of LWR with 1 GWe. The design study was performed mainly for the subcritical reactor and the spallation target with a beam window. In Japan, Atomic Energy Commission (AEC) has implemented the check and review (C&R) on P&T technology from 2008 to 2009. In the C&R, the benefit of P&T technology, the current status of the R&D, and the way forward to promote it were discussed.

Nuclear Power – A Panacea for Future Energy Needs?

Each week seems to bring further evidence that the Earth is warming at a faster rate than previously estimated. Pressure is building to replace power sources that emit carbon dioxide with those tha...

Advances in 79Se analyses on Savannah river site radioactive waste matrices

Waste cleanup efforts underway at the United States Department of Energy’s (DOE) Savannah River Site (SRS) in South Carolina, as well as other DOE nuclear sites, have created a need to characterize 79Se in radioactive waste inventories. Successful analysis of 79Se in high activity waste matrices is challenging for a variety of reasons. As a result of these unique challenges, the successful quantification of 79Se in the types of matrices present at SRS requires an extremely efficient and selective separation of 79Se from high levels of interfering radionuclides. A robust 79Se radiochemical separation method has been developed at the Savannah River National Laboratory (SRNL) which is routinely capable of successfully purifying 79Se from a wide range of interfering radioactive species. In addition to dramatic improvements in the Kd, ease, and reproducibility of the analysis, the laboratory time has been reduced from several days to only 6 h.

Study of the nuclide inventory of operational radioactive waste for the RBMK-1500 reactor

The experimental and modeling results on the radionuclide concentrations in the Ignalina NPP operational waste are presented in the work. The scaling factors between easy-to-measure γ emitters 137Cs, 60Co and a number of difficult-to-measure radionuclides, the activity measurements of which are related to radiochemical procedures, α and β spectrometry, have been determined. The study shows that the scaling factor method can be applied for RBMK-1500 reactor waste characterization. The scaling factors were used in determination of the nuclide composition of operational radioactive waste and characterization of radioactive waste during the Ignalina NPP decommissioning.

La gestion des déchets du démantèlement

The availability of long term waste management routes is a condition for the success of decommissioning programs. The 28th of June 2006 waste act provides a new framework to assess the relevancy of the French waste management program, with the implementation of National Waste Management Plan. Input data for this Plan are provided by the National Inventory of Radioactive Waste that is issued by ANDRA with a triennial periodicity. The National Inventory considers operational wastes as well as decommissioning wastes.More than 90% of radioactive waste that are generated in France can be accommodated in existing surface disposal facilities : in Centre de l’Aube disposal facility for low and intermediate short lived wastes, in Morvilliers disposal facility for very low level wastes.During the past twenty years annual deliveries to Centre de l’Aube have been divided by a factor of nearly 3, thanks to great efforts by nuclear facilities operators to reduce operational waste production. Therefore Centre de l’Aube should be able to take in charge an additional flow for decommissioning wastes that could double the present annual flow.The design of Morvilliers facility takes into account wastes to be generated by decommissioning works for thirty years according to the particular French regulatory framework. This framework prescribes the implementation of a waste zoning to segregate conventional wastes and nuclear wastes. Nuclear wastes have to be managed within a reinforced traceability management route.The flexibility of surface disposal facilities enables the disposal of large components. It has been tested in Centre de l’Aube and in Morvilliers facilities. An industrial approach should now be promoted for these wastes, depending on the forecast inventory for such wastes. However the relevancy of this disposal mode should be assessed for each waste, considering its advantages not only for dismantling works, but also for transportation and disposal issues, in particular with regards to the occupancy of the disposal volume capacity.According to the waste act of June 2006, the 28th , these disposal routes should be completed by 2019 for graphite waste by a dedicated repository for low level long lived wastes and by 2025 by a deep geological repository for high level waste and intermediate level long lived wastes.Disposal facilities are indeed rare resources. Therefore incentives for waste volume reduction should be searched and recycling routes within the nuclear industry should be encouraged for some kinds of very low contaminated waste (i.e. metallic wastes). A tight dialogue between ANDRA and dismantlers is necessary that can take benefit from the national and the international experiences.

「ふげん」の廃止措置における被ばく低減の取り組み

Operation of the Fugen nuclear power station ended in March 2003, and the preparations for decommissioning have started. Fugen has been preparing for the project, and various evaluations and studies are underway, including evaluation of radioactive waste inventory, improvement of decontamination for decommissioning, development of a tritium decontamination and decommissioning engineering support system, etc. Activities to reduce the occupational radioactivity dosage during the decommissioning process are also discussed.

Nuclear power: waste management issues

Of all the aspects of nuclear power in the UK, none is so contentious or so pivotal as the issue of nuclear waste and its management. While there is no immediate cause for alarm, a huge amount of improvement is needed if the UK's custody of its radioactive waste is to become a programmed and prosecuted success. This paper discusses the UK radioactive waste inventory, UK radioactive waste policy, and radioactive waste storage.

Probabilistic safety assessment model for near surface radioactive waste disposal facilities

A probabilistic safety assessment model has been developed for assessing the performance of near surface disposal facilities for low-level radioactive waste. Two modes of disposal such as single dump and multiple dump are considered in the model. The model is composed of four components: source term, repository failure, geosphere transport and radiological assessment. The source term contains low-level radioactive waste equivalent to 50 GWe.y energy production (1 GWe.y=3.2×10 16 J of electrical energy production) either disposed at an instant or distributed over 50 years. The endpoints of assessment are expressed as radioactivity release rate, radionuclide concentration in ground water, radiation dose to a member of the critical group through drinking water pathway and total risk to critical group due to disposal practice. Sensitivity analysis is carried out to identify the critical parameters, which have maximum effect on the assessment endpoints. Uncertainty analysis, based on random selection of all main parameters, is also carried out to identify the effect of overall variation of parameters used in the model in relation to a reference level. The reference level delivers a maximum annual effective dose of 1.2×10 −2 mSv to a member of the critical group after about 1.25×10 2 years of disposal mostly from 129I, the long-lived and less sorbing radionuclide. The corresponding risk to the public due to the disposal practice (9.0×10 −7 y −1) is found to be lower than that due to natural background radiation. The most critical parameters as indicated by the sensitivity analysis are the distribution coefficient of radionuclides, seepage velocity in the unsaturated zone between the facility and the water table, dispersivity in ground water and thickness of the unsaturated zone. The uncertainty analysis shows that 129I is the critical radionuclide delivering maximum dose in most cases though it constitutes a low percentage in the low-level radioactive waste inventory. The annual effective doses derived from the uncertainty analysis fall in a log normal distribution with a geometric mean of 3.6×10 −2±3.9 mSv and the most probable annual effective dose to a member of the critical group works out to be 2.8×10 −4 mSv.

How will we manage the waste from reactor decommissioning?

This paper aims to give a brief overview of the issues surrounding the radioactive waste management aspects of reactor decommissioning, concentrating on those aspects which are relevant to the UK's fleet of Magnox reactors. It outlines the UK's reactor decommissioning strategy and describes how the radioactive waste inventory of a decommissioned site, knowledge of which is critical for strategy development, is determined. The routes by which the waste can be disposed of are then reviewed together with current experience of decommissioning waste management on a commercial nuclear power station. Finally, the major challenges in managing radioactive waste from the eventual dismantling of reactors are discussed.

How will we manage the waste from reactor decommissioning?

This paper aims to give a brief overview of the issues surrounding the radioactive waste management aspects of reactor decommissioning, concentrating on those aspects which are relevant to the UK's fleet of Magnox reactors. It outlines the UK's reactor decommissioning strategy and describes how the radioactive waste inventory of a decommissioned site, knowledge of which is critical for strategy development, is determined. The routes by which the waste can be disposed of are then reviewed together with current experience of decommissioning waste management on a commercial nuclear power station. Finally, the major challenges in managing radioactive waste from the eventual dismantling of reactors are discussed.

Radioactive contamination in the environment of the nuclear enterprise ‘Mayak’ PA. Results from the joint Russian-Norwegian field work in 1994

A brief overview of the radioactive waste inventory of the ‘Mayak’ PA reprocessing plant, Chelyabinsk Region, Russia is given together with a description of the environmental contamination caused by its activities and the origins of contamination. The joint Russian-Norwegian field work in 1994 is described, together with the major analytical results. The field work was of a limited extent, and was not designed to include a complete mapping of the environmental contamination around the plant. The results are, however, in good agreement with the very extensive previous Russian investigations. The highest concentrations of radioactivity were found in Reservoirs 10 and 11 and at the floodplain of the upper Techa River (Asanov Swamp). Also high concentrations are found in biota, especially fish from Reservoir 10.

Nuclear Contamination from Weapons Complexes in the Former Soviet Union and the United States

Over a 50-year period, the Soviet Union and the United States developed the largest nuclear weapons complexes in the world. In doing so, they also created the world's largest inventories of radioactive waste. Although some of the waste has been stored in safely managed systems such as tanks or converted into stable and storable forms such as glass, significant amounts of it have been released into the environment. This article focuses primarily on these weapons-related discharges because of their size and less-well-known nature.

95/06054 Integrated data base report — 1993: U.S. spent nuclear fuels and radioactive waste inventories, projections and characteristics

A new assembly concept, designated APA (for Advanced Plutonium fuel Assembly), should make it possible to multi-recycle plutonium in pressurized water reactors. The basic idea is founded on the manufacture of a large plutonium thin annular fuel rod with an inert support, cooled on both faces. The absence of plutonium generation, combined with moderate fuel temperature should make it possible to achieve substantial burn-up fractions in these rods. The assembly is compatible with the internals of a Pressurized Water Reactor (PWR), and provides for permanent reversibility. Neutronic studies showed a compliance with actual safety/control criteria. A multi-recycling scenario was simulated for 84 years' operation with a 65 GW electrical power installed capacity, comprising forty-five 1450 MW electrical power PWRs, 32 of which are loaded with UO2 and 13 with APAs. It showed that the plutonium inventory is controlled. Thermal-hydraulic studies showed one can find an annular rod geometry allowing one to respect both margins to Critical Heat Flux (CHF) during normal and accidental operations and void fraction limitations.