Academic literature on the topic 'Nuclear engineering (including fuel enrichment and nuclear waste processing and storage)'

Recently, issues related to the effects (benefit or harm) of processing nuclear waste and its further use as fuel have been increasingly often raised in the scientific discussion. In this regard, the research aims to investigate issues related to the assessment of the economic potential of nuclear waste use, as well as the cooperation between states in the context of the reduction of risks associated with nuclear waste storage and processing. The research methodology is based on an integrated approach, including statistical, factor analysis, and the proposed system of performance indicators for managing spent nuclear fuel use. The research was carried out on the basis of materials from Russia and the EU countries. In the course of the study, a model of cooperation between states has been developed (based on the example of technologies and methods of processing nuclear waste used in the EU and Russia) according to the nuclear waste (spent nuclear fuel) management algorithm. The model considers the risks and threats associated with ecology and safety. The developments and other results described in the study should be used in further research devoted to the use of nuclear waste as heat-producing elements.

Austenitic stainless steels have received much attention in recent years due to their excellent combination of corrosion, mechanical and wear properties. They are finding wide applications in chemical, power, oil, refinery, biomedical, marine sectors and other industries where both good mechanical properties and excellent corrosion and wear resistances are demanded. In the spent nuclear fuel reprocessing plants and waste storage and processing plants involving nitric acid as the main process medium, type 304L stainless steels (SS) are employed as work horse materials for manufacturing more than 90% of the plant components. Though these alloys form a protective Cr2O3 passive film over the surface in nitric acid under plant operating conditions, they undergo various types of corrosion failures in service. Welding and other metallurgical parameters including alloying elements, cold working, heat treatment etc. degrade the performance of the alloy in service. For qualifying the alloy for plant applications, ASTM A262 practice A and C are currently employed, however, long term performance under simulated plant operating conditions is necessary to understand the failure modes and life prediction of components. Today, nitrogen represents an economically, environmentally, attractive and versatile alloying element to steels and stainless steels. The beneficial effect of nitrogen alloying in stainless steels are manifolds, including solid solution strengthening, precipitation effects, phase control and corrosion and wear resistances. Recent years have seen a rapid development of these alloys with improved properties owing to advances in alloy processing technologies. The objective of the lecture is to bring out the various corrosion issues in reprocessing plants, short term laboratory versus long term field corrosion data, modeling for life prediction, effect of redox ions, nitrogen alloying, welding and corrosion damage, etc. and highlight the remedial actions to overcome the shortcomings due to corrosion issues.

A major Russian political and economic objective is to increase exports, particularly for front-end fuel cycle services through Tenex, as well as nuclear power plants. Russia uses about 3800 tonnes of natural uranium per year. After enrichment, this becomes 190 tU enriched to 4.3% for 9 VVER-1000 reactors (at 2004, now 13), 60 tU enriched to 3.6% for 6 VVER-440s, 350 tU enriched to 2.0% for 11 RBMK units, and 6 tU enriched to 20% (with 9 tU depleted) for the BN-600. Some 90 tU recycled supplements the RBMK supply at about 2% enrichment. This RepU arises from reprocessing the used fuel from BN, VVER-440 and marine and research reactors. There is high-level concern about the development of new uranium deposits, and a Federal Council meeting in April 2015 agreed to continue the federal financing of exploration and estimation works in Vitimsky Uranium Region in Buryatia. It also agreed to financing construction of the engineering infrastructure of Mine No. 6 of Priargunsky Industrial Mining and Chemical Union (PIMCU). The following month the Council approved key support measures including the introduction of a zero rate for mining tax and property tax; simplification of the system of granting subsoil use rights; inclusion of the Economic Development of the Far East and Trans-Baikal up to 2018 policy in the Federal Target Program; and the development of infrastructure in Krasnokamensk. In June 2015 Rosgeologia signed a number of agreements to expedite mineral exploration in Russia, including one with Rosatom. It was established in July 2011 by presidential decree and consists of 38 enterprises located in 30 regions across Russia, but uranium is a minor part of its interests. Russia is engaged in international nuclear energy markets, far from the traditional sites of Eastern Europe. In June 2011, Rosatom announced that it was creating a "Rusatom" overseas company, a new structure responsible for building projects that could not benefit from them. It can be executed as a primary contractor as well as as owner of foreign capacities under a self-exploitation agreement (BOO). She actively strives for shopping in developing countries and has set up eight offices abroad. The Soviet Union also used 116 nuclear explosions (81 in Russia) for geological research, creating underground gas storage, boosting oil and gas production and excavating reservoirs and canals. Most were in the 3-10 kiloton range and all occurred 1965-88.

According to current forecasts, nuclear power plant construction and nuclear-generated electricity production is projected to increase in the next half-century. This is likely due to the fact that nuclear energy is an ‘environmental alternative’ to fossil fuel plants that emit greenhouse gases (GHG). Nuclear power also has a much higher energy density output than other alternative energy sources such as solar, wind, and biomass energies. There is also growing consensus that processing of low- and high-level waste, LLW and HLW respectively, is a political issue rather than a technical challenge. Prudent implementation of a closed fuel cycle not only curbs build-up of GHGs, but can equally mitigate the need to store nuclear used fuel. The Global Nuclear Energy Partnership (GNEP) is promoting gradual integration of fuel reprocessing, and deployment of fast reactors (FRs) into the global fleet for long-term uranium resource usage. The use of mixed oxide (MOX) fuel burning Light Water Reactors (LWR) has also been suggested by fuel cycle researchers. This study concentrated on modeling the construction and decommissioning rates of six major facilities comprising the nuclear fuel cycle, as follows: (1) current LWRs decommissioned at 60-years service life, (2) new LWRs burning MOX fuel, (3) new (Gen’ III+) LWRs to replace units and/or be added to the fleet, (4) new FRs to be added to the fleet, (5) new reprocessing and MOX fuel fabrication facilities and (6) new LWR fuel fabrication facilities. Our initial work [1] focused on modeling the construction and decommissioning rates of reactors to be deployed. This is being followed with a ‘mass flow model’, starting from uranium ore and following it to spent forms. The visual dynamic modeling program Vensim was used to create a system of equations and variables to track the mass flows from enrichment, fabrication, burn-up, and the back-end of the fuel cycle. Sensible construction and deployment rates were benchmarked against recent reports and then plausible scenarios considered parametrically. The timeline starts in 2007 and extends in a preliminary model to 2057; a further mass flow model scenario continues until 2107. The scenarios considered provide estimates of the uranium ore requirements, quantities of LLW and HLW production, and waste storage volume needs. The results of this study suggest the number of reprocessing facilities necessary to stabilize and/or reduce recently reported levels of spent fuel inventory. Preliminary results indicate that the entire national spent fuel inventory produced over the next ∼50 years can be reprocessed by a reprocessing plant construction rate of less than 0.07 plants/year (small capacity) or less than 0.05 plants /year (large capacity). Any larger construction rate could reduce the spent fuel inventory destined for storage. These and additional results will be presented.

The government of Iraq, through the Ministry of Science and Technology (MoST) is decommissioning Iraq’s former nuclear facilities. The 18 former facilities at the Al-Tuwaitha Nuclear Research Center near Baghdad include partially destroyed research reactors, a fuel fabrication facility and radioisotope production facilities. These 18 former facilities contain large numbers of silos and drums of uncharacterized radioactive waste and approximately 30 tanks that contain or did contain uncharacterized liquid radioactive wastes. Other key sites outside of Al Tuwaitha include facilities at Jesira (uranium processing and waste storage facility), Rashdiya (centrifuge facility) and Tarmiya (enrichment plant). The newly created Radioactive Waste Treatment Management Directorate (RWTMD) within MoST is responsible for Iraq’s centralized management of radioactive waste, including safe and secure disposal. In addition to being responsible for the uncharacterized wastes at Al Tuwaitha, the RWTMD will be responsible for future decommissioning wastes, approximately 900 disused sealed radioactive sources, and unknown quantities of NORM wastes from oil production in Iraq. This paper presents the challenges and progress that the RWTMD has made in setting-up a radioactive waste management program. The progress includes the establishment of a staffing structure, staff, participation in international training, rehabilitation of portions of the former Radioactive Waste Treatment Station at Al-Tuwaitha and the acquisition of equipment.