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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Optical/UV-to-X-Ray Echoes from the Tidal Disruption Flare ASASSN-14li

We carried out the first multi-wavelength (optical/UV and X-ray) photometric reverberation mapping of a tidal disruption flare (TDF) ASASSN-14li. We find that its X-ray variations are correlated with and lag the optical/UV fluctuations by 32 ± 4 days. Based on the direction and the magnitude of the X-ray time lag, we rule out X-ray reprocessing and direct emission from a standard circular thin disk as the dominant source of its optical/UV emission. The lag magnitude also rules out an AGN disk-driven instability as the origin of ASASSN-14li and thus strongly supports the tidal disruption picture for this event and similar objects. We suggest that the majority of the optical/UV emission likely originates from debris stream self-interactions. Perturbations at the self-interaction sites produce optical/UV variability and travel down to the black hole where they modulate the X-rays. The time lag between the optical/UV and the X-rays variations thus correspond to the time taken by these fluctuations to travel from the self-interaction site to close to the black hole. We further discuss these time lags within the context of the three variants of the self-interaction model. High-cadence monitoring observations of future TDFs will be sensitive enough to detect these echoes and would allow us to establish the origin of optical/UV emission in TDFs in general.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Mid-infrared Variability of Changing-look AGNs

It is known that some active galactic nuclei (AGNs) transit from Type 1 to Type 2 or vice versa. There are two explanations for the so-called changing-look AGNs: one is the dramatic change of the obscuration along the line of sight, and the other is the variation of accretion rate. In this Letter, we report the detection of large amplitude variations in the mid-infrared luminosity during the transitions in 10 changing-look AGNs using the Wide-field Infrared Survey Explorer ( WISE ) and newly released Near-Earth Object WISE Reactivation data. The mid-infrared light curves of 10 objects echo the variability in the optical band with a time lag expected for dust reprocessing. The large variability amplitude is inconsistent with the scenario of varying obscuration, rather it supports the scheme of dramatic change in the accretion rate.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

The Role of Pulse Radiolysis in Advanced Nuclear Fuel Cycles

The effects of ionizing radiation are ubiquitous throughout all aspects of a nuclear fuel cycle. The complexity and intensity of these effects are greatest during reactor operations and in the management of used nuclear fuel and waste. Radiation-induced processes typically promote the chemical transformation of molecules and materials with the formation of potentially detrimental degradation products and corresponding changes in physical and chemical properties, which ultimately impact the effectiveness and longevity of nuclear technologies. Consequently, a molecular-level understanding of radiation effects over multiple time, distance, and material domains is essential for the innovation and deployment of next generation nuclear technologies. Attaining this knowledge necessitates a firm grasp of radiation-induced reaction kinetics, for which pulsed electron radiolysis is the methodology of choice. Presented here are several recent studies from our group that demonstrate the critical role of pulsed electron radiolysis techniques in the advancement of our understanding of radiation-induced chemistry under advanced nuclear fuel cycle conditions. Research topics include late actinide redox chemistry, radiation robustness of used nuclear fuel reprocessing complexants, and the behavior of metal cations in high temperature molten salt media.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2017

LaserSnake2: An Innovative Approach to Nuclear Decommissioning - 17080

Nuclear decommissioning challenges exist the world over and require innovative approaches to ensure safe and cost effective dismantling of high hazard nuclear facilities. LaserSnake technology makes use of the flexibility and dexterity of snake arm robots to deploy high-powered laser cutting, lifting and manipulation tools. This paper describes the development and use of the system to achieve the successful size reduction and removal of a substantial stainless steel vessel within the First Generation Reprocessing Plant (FGRP) at Sellafield in the UK. Due to the environment, nuclear decommissioning is an extremely challenging activity. High ambient radiation levels often preclude entry to the areas involved, and as industry tries to minimise dose uptake, even moderate radiation levels now require remote solutions. 'In-situ' size reduction of process plant, including vessels and pipework, will allow the removal of the nuclear inventory from a building prior to further decontamination and demolition. The term 'in situ' is in this case used to mean work done on plant items within their existing cells as opposed to moving items from their original location to a dedicated size reduction facility. Traditional size reduction cutting methods, such as reciprocating saws or grinders, pose a significant challenge for remote deployment platforms. This includes the loss of haptic feedback and the length of time taken to perform the task, and difficulty dealing with the reaction forces. Although remote engineered solutions for these tools are possible, they are are typically complicated, unreliable and expensive. Robot deployed laser cutting is widely used in non-nuclear industrial sectors, and offers a simpler method for size reduction. LaserSnake2 is a UK collaborative project, co-funded by the Nuclear Decommissioning Authority, Innovate UK and the Department of Energy and Climate Change. The project combined the skills of robotic experts and laser and optic specialists, to develop a remote handling technology suited for deployment within active nuclear environments. As well as meeting strict safety case requirements, the system provides a safe and cost effective method for decommissioning of complex nuclear spaces. An overview of the system development and deployment is presented in this paper. In July 2016, a successful decommissioning campaign was conducted in the FGRP at Sellafield. The LaserSnake2 system was used to size reduce a double-skinned dissolver vessel within a radiologically active nuclear cell. Planning of the size reduction method and processes, as well as results of the campaign itself are described in this paper. The containment procedures and radiological considerations for the system are presented along with the effects of operations on the cell and ventilation systems. LaserSnake, developed as a modular arm system with up to 4.5 m of articulation, carries an integrated tool comprising a high power, decommissioning specific, laser cutting head, high definition cameras and high powered illumination LEDs. It is designed for precise dismantling work within confined and hazardous environments. The tool can be interchanged, allowing the snake-arm robot also to carry grippers, environmental mapping sensors and other tools which may prove advantageous during a decommissioning campaign. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Benefits from developments in the field of Decommissioning for Fukushima Daiichi fuel debris retrieval: Remote-Controlled Laser Cutting Process - 17110

Among the numerous challenges towards the decommissioning of Fukushima Dai-ichi reactors, removing fuel debris is certainly one of the tougher ones, requiring several technical developments. One of them, related to laser cutting of fuel debris is being developed by a French consortium 'ONET Technologies, CEA and IRSN'. Remote controlled laser cutting was implemented for the first time in a real decommissioning workshop in 2015, in UP1 reprocessing plant. In addition to laser cutting development in air and underwater, key aspects of fuel debris cutting of representative of corium debris simulants was performed to test the quantities of aerosols, gas and dusts released during the debris laser cutting. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2017

Remediation of the FGMSP at Sellafield: The First Transfer of Bulk Sludge - 17133

The very first bulk transfers of radioactive sludge have commenced from one of the most hazardous nuclear plants in Europe, using equipment and systems researched, designed, installed and commissioned by Jacobs as part of the ACKtiv alliance. Sellafield is a nuclear fuel reprocessing and decommissioning site, close to the village of Seascale on the coast of the Irish Sea in Cumbria, England. Sellafield incorporates the original nuclear reactor site at Windscale, which is currently undergoing decommissioning, and dismantling, and Calder Hall, the world's first nuclear power generating reactor. The first nuclear facilities were built in the 1940's.The First Generation Magnox Storage Pond (FGMSP) dates back to the 1950's as part of the UK's expanding nuclear programme and was constructed to store, cool and prepare used Magnox nuclear fuel for recycling into new fuel. It urgently needs to be emptied of 1500 cubic metres of radioactive sludge. In this paper we describe the work undertaken by Jacobs to deliver a very challenging programme of work to provide the capability to remove sludge from the pond. The FGMSP Retrievals Project was awarded in March 2007 to supply equipment and services for the removal of sludge and miscellaneous waste from the First Generation Magnox Storage Pond at Sellafield. The Project is being executed by ACKtiv Nuclear (Jacobs, Carillion and Atkins) of which Jacobs is a 40% stakeholder. ACKtiv Nuclear is a mature Joint Venture and has been operating continuously and successfully since 2002, the oldest JV still in operation on Sellafield Site. The roots of the JV can be traced back to the 1980's. The Project covers all project phases from front-end engineering through detailed design, procurement, installation and commissioning support. The Project places huge emphasis on off-Site testing and has several facilities for both installation and integrated testing. This proves equipment prior to installation in a radioactive environment. The Project has achieved success and recognition including winning the 2014 and 2015 Sellafield Business Excellence awards, as well as numerous internal Jacobs awards. The Project achieved a major decommissioning milestone in March 2016. Since the installation of a 31 m pipe-bridge in 2012, using a 1200 te mobile crane surrounded by several other facilities with nuclear inventory, the Project has successfully installed the sludge retrieval and effluent system into the FGMSP. This 4 year programme of work included 2 booster pump platforms, sludge recovery tooling, hoses, umbilicals and a deluge skip wash box which were all trialled and proven off-Site prior to installation in the pond. This milestone to commence transfer of sludge to modern stainless steel containment is a major step forward in the hazard reduction of the facility.The presentation will cover the installation of the pond de-sludging equipment, the innovations deployed that ensured that the milestone was achieved under budget and ahead of schedule, as well the benefits to the facility, the Site and the nuclear industry. It will also examine the challenges that needed to be overcome such as high dose, contamination, limited working times and space constraints. The presentation will describe why the work is of national Importance and conclude with the achievement of commencement of bulk sludge transfer to a modern facility. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Water Cleaning System for the Exhaust Pipe of HLW Glass Melter (LFCM) - 17180

Vitrification technology has been generally applied to stabilize High-Level Radioactive Waste (HLW) generated from spent fuel reprocessing. In Japan, Joule Heated Liquid Fed Ceramic Melter (LFCM) system is selected for HLW vitrification and the recent active test has been successfully demonstrated its stable operation. The higher reliability of off-gas treatment system (OGTS) which consists of wet scrubber, absorbers and filters connected to the LFCM is also important to ensure long term system operation. The OGTS removes radioactive gases, mists and dust generated by LFCM and maintains radioactive containments by keeping negative pressure inside. In the past active and inactive tests, it was observed that differential pressure in the exhaust pipe attached to LFCM gradually increased during continuous operation and some deposits were observed inside the off-gas pipe. So the cleaning operation needs to be improved and more frequent in order to avoid the exhaust pipe clogging. Therefore we investigated several cleaning systems and operational methods for the exhaust pipe of LFCM. As a result, we have successfully developed the modified water cleaning system. In this presentation we will introduce our water cleaning system. In addition, we will present the result of inactive mock-up tests for the visualization of this water cleaning system. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Experience in Decommissioning of Nuclear Fuel Cycle Facilities in Germany - 17195

Several nuclear fuel cycle facilities have been decommissioned in Germany and the sites released from regulatory control. There is an overview of past and current decommissioning projects of fuel cycle facilities, either past fuel element fabrication facilities or past and current (experimental) reprocessing facilities. Several examples of technological advances are given, being developed due to obstacles, which occurred during conduct of these decommissioning projects. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Understanding Uranium Binding Mechanisms and Speciation on Stainless Steel - 17462

Stainless steels have been exposed to nitric acid solutions containing natural uranium under similar conditions to those found in reprocessing plants. Solution and solid analysis of the stainless steel samples has been undertaken to describe the contamination phenomenon. General corrosion of the surface was seen to take place over the month-long experiments. Contamination has been shown on all exposed surfaces. Solution analysis indicates that an equilibrium state is reached after 2 weeks exposure to the 12 M HNO{sub 3}. Surface analysis through autoradiography and X-ray absorption near edge structure (XANES) indicate that multiple mechanisms of uptake may occur and consequently concentrated regions of contamination may be produced. (authors)

36 MATERIALS SCIENCE↗
DOE OSTI2017

Pile Fuel Cladding Silo Deflector Plate Removal Project Using Long Reach Tooling and Suspended Abrasive Water Jet Cutting System - 17541

The Pile Fuel Cladding Silo (PFCS) at the Sellafield decommissioning, reprocessing and nuclear waste management facility in the UK was constructed in the late 1940-s and used for the storage of Intermediate Level Waste (ILW) arising from the Windscale Piles, Calderhall and Chapelcross Reactors until the 1960's. The PFCS is 21 metres high and comprises 6 identical tall compartments with the waste added to the silo via a charge-hole at the top of each compartment; each compartment is split by a central dividing wall that runs from the base of the silo to a few metres below the underside of the silo roof. A deflector plate assembly (DPA) supported on two horizontal beams is located between the top of the dividing wall and the roof and allowed the waste to spread as it fell into the silo and prevent excessive mounding. Sellafield Ltd is currently engaged in an overall programme of works to remove the waste for storage within modern ILW containers. Prior to the commencement of these works the Deflector Plate Assemblies (DPA) and beam structures within the silos are required to be removed to allow access for the waste retrievals equipment through the side of the silo at the point where the DPAs are situated. James Fisher Nuclear (JFN) and Sellafield Ltd have developed a system using suspended water jet cutting equipment combined with custom long reach tooling, installed through penetrations made in the side of the silo, to enable the remote size reduction of the DPA and beams within each compartment. The use of a low pressure suspended water jet cutting system has enabled a single water/abrasive hose to be routed down a tool deployment pole and allowed long hose lengths up to 80 m from pump to nozzle enabling siting of equipment on a congested and difficult access site. The use of lightweight, yet high strength, carbon fibre poles within the tools has enabled the deployment of tool end effectors at distances of up to 6.5 m from the compartment walls using a relatively small 60 mm diameter pole. This maximised articulation of the pole within the 300 mm wall penetrations to reach all areas of the DPA. Capability of the operators to install the tooling and size reduce DPA and beam assemblies have been demonstrated through the training on a Full Scale Test Rig (FSTR). The FSTR was integral to the development of the equipment and techniques and to providing assurance to the client that the project was technically achievable given the tight building restraints and safety issues. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

The Micro-Optical Ring Electrode: A Sensor for Multiple Actinide Ions Monitoring - 17586

We present on the development of the Micro-Optical Ring Electrode (MORE) for the analysis of trans-uranium elements in aqueous mixtures. The MORE is a photo-electrochemical device based on a ring microelectrode that uses the insulator interior to the ring as a light guide. This single device exploits the unique photophysical and electrochemical properties of multiple analytes present in mixtures to quantify them. Our study aims to develop a protocol for the analysis of ions of uranium, neptunium and plutonium, which are most relevant to the nuclear industry, especially in the areas of decommissioning and fuel reprocessing, where speedy and safe identification of radioactive contaminants is essential. The technique offers a number of advantages over traditional methods in the area of radiochemical analysis such as real time monitoring in-situ, reduced radiation dose impact to the analyst as a result of greatly reduced sample handling and preparation, improved analysis times allowing quick decision making, at a much reduced cost (e.g. compared to ICP-MS and Scintillation counting). Here we present results of our study on non-radioactive surrogates for the target elements and discuss the advantages the technique can deliver to the nuclear industry. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Drying Simulated Advanced Gas Reactor Fuel: Proving the Concept - 17637

Spent Nuclear Fuel (SNF) reprocessing is due to cease in the UK in 2018 and a new interim storage method may be required if it is found that pond storage is not viable beyond the 25 year period which is currently understood to be safe. Dry storage has been used elsewhere in the world for zircaloy and aluminium clad fuel and has been proposed for use in the UK, however since the UK's fuel is predominantly stainless steel (SS) clad, testing will need to be carried out to ensure that drying methods are suitable. This will require representative samples for macro scale drying tests. To date, little long term stored fuel has been examined. As a result, work has been carried out to try and ascertain whether the corrosion associated with long term storage leads to significant bound water and whether through wall cracks can be formed in intact lengths of SS tube. It was found that unlike an aluminium simulant, corroded SS showed no sign of water loss as a result of oxide dehydration during controlled drying by thermogravimetric analysis, and consequently bound water could be disregarded. It was also found that through wall cracks could be produced in an intact length of SS tube which would be suitable for macro scale drying tests. Some initial macro scale drying tests have been carried out using an alternative test piece with preformed cracks, and three distinct drying regimes to complete dryness have been detected. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Preparation of Waste Fingerprints for the Miscellaneous Beta Gamma Waste Feeds to the Box Encapsulation Plant at Sellafield - 16080

There are a number of legacy pond and silo storage facilities on Sellafield Site that contain a broad range of ILW arising from the early Windscale Pile and Magnox Fuel Reprocessing Programmes. The waste comprises of solid Miscellaneous Beta Gamma Waste (MBGW) from operations (including filters, containerised waste, thermocouple wire, support struts, pumps, soft wastes) and associated sludges that have arisen from the corrosion of the fuel, Magnox Swarf cladding and the MBGW. It is intended to retrieve and package this waste to meet the requirements of interim storage and final disposal in the Box Encapsulation Plant (BEP) at Sellafield. As part of this process each package must be assigned a realistic and justifiable radionuclide and material inventory. These inventories can either be assigned by radiometric measurements including the associated errors or developed by fundamental data underpinning these assessments and a 'chain of custody' approach of knowing where the waste has been and how it has evolved. The subject of this paper is concerned with the development of the waste fingerprints for these legacy waste streams. As the wastes have arisen over a ∼70 year period there have been an assortment of different working practices and developments in equipment design that have led to significant variations in the waste condition and its composition. During storage the waste items have become mixed, corroded and sludge deposits have arisen. Because of this, and that early consignment records are either incomplete or missing, the task of assigning material and radionuclide fingerprints has been very challenging. In addition, to comply with regulatory requirements the inventory assignment has to be sufficiently robust to meet the processing envelope of the encapsulation process i.e. to allow controls to be made on the amounts of reactive materials (e.g. aluminium, Magnox and uranium) that can be processed within each product and allow identification of excluded items from being consigned from the donor plants. Also, as the waste comprises actinides, fission and activation products it was noted that whilst the UK standard inventory code FISPIN10 predicts the actinides and fission products well, there was a significant discrepancy in the prediction of activation products when compared with those predicted by the specialised fusion code FISPACT. It should be noted that the use of FISPACT to predict actinides and fission products is not recommended. To address these issues, - position statements were produced for each of the waste streams that would be consigned to BEP; - gaps within the data were assessed and where possible inactive trial work was identified to address it; - material and radionuclide fingerprint justification documents were developed from the position statements based upon available data, the experimental work and justified assumptions; - where FISPIN runs were required, these were run with a modified activation data library based on the European Activation File 2010 (EAF2010) to model the activation products. This paper summarises the BEP process, discusses examples of how the material and radionuclide waste stream fingerprints have been justified by revisiting the sample data, original consignment records, engineering drawings and recent remotely operated vehicle (ROV) pond surveys and making reasoned assumptions based on operational practices and non-active experimental work. Incorporation of the EAF2010 library within the FISPIN code has offered significant benefits to BEP and indeed other plants processing mixed fission and activated wastes as it allows comparable predictions of activation products compared with that made by FISPACT and for the plant to maintain one data processing stream rather than two if it had to utilise both modelling codes. This work will underpin the inventory submission in support of the Interim Letter of Compliance (ILoC) to Radioactive Waste Management Limited (RWM). The process of examining the original records, plant operation schedules and engineering drawings has enabled removal of some of the pessimisms that have been made in previous assessments. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

The INFODEM Information Centre at CEA Marcoule: A Unique Information Tool in Europe About Nuclear Decommissioning - 16217

In September 2014, the French Alternative Energies and Atomic Energy Commission (CEA) inaugurated a unique information center focused on decommissioning of its nuclear facilities. This facility, named INFODEM information center, is inside the main building of the G1 nuclear reactor at Marcoule, a nuclear site in the south of France with world-recognized expertise in decommissioning. Constructed in the 1950's, the G1 reactor was the first industrial-scale reactor for plutonium production in France; it was also used to produce electricity. Operations ceased in 1968, and it was progressively dismantled (through removal of fuel and main components) and placed in monitoring status. In the 1980s, mockups of fuel cycle process equipment were built under a temporary mission to support development activities for the La Hague reprocessing plant. When that ended, further dismantling occurred, and during 1996 through 2010, the site established itself as a reference example for worldwide nuclear dismantling activities. In 2012, the project to establish an information center at the reactor began, targeting three main audiences: the public, agency personnel and politicians, and technical professionals. Considerable thought went into the facility design, to address the interests and information needs of these three audiences. The INFODEM concept extended over 800 square meters (about 960 square yards), to host an informative tour addressing several major themes: CEA's D and D strategy, programs, skills, tools and methodologies and 'everyday life' on decommissioning projects. Illustrating its unique value and considerable success, INFODEM received the Public Information Prize from the French Nuclear Energy Society (SFEN) in June 2015. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Preferred Concepts for Disposal of the UK Inventory of Depleted, Natural and Low Enriched Uranium - 16382

Depleted, natural and low enriched uranium (DNLEU) forms a significant quantity of the UK inventory of higher activity radioactive materials. The great majority comprises uranic materials produced from uranium enrichment operations and from reprocessing of spent nuclear fuels. The most recent estimate of the total quantity (stocks plus arisings) of UK-owned DNLEU from civil nuclear operations is 170,000 tU. Current UK Government strategy is for DNLEU to be stored indefinitely in existing or new facilities, as required. However, Government strategy for long-term management of uranic materials is under review and a change could potentially cause this material to be reclassified as a waste. An Integrated Project Team (IPT) was formed in 2012 with the objective of identifying and addressing the issues associated with the potential need to dispose of DNLEU, in order to inform wider decision-making on the long-term management of UK DNLEU. Key technical issues considered by the IPT relate to the following: 1. The need for an improved understanding of the UK DNLEU inventory. 2. The identification of preferred chemical and physical form(s), and preferred packaging and disposal concepts for DNLEU - the main subject of this paper. 3. The approach to safety assessment of DNLEU disposal. This paper summarises the disposal concepts under consideration by the IPT, and the rationale for identification of preferred concepts for disposal of DNLEU inventory components. The conclusions will be of interest to other programmes and countries with a requirement to manage large quantities of similar materials. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Application of Modular Design in Abatement of Fuel Element Debris (FED) Liquid Waste Stream - 16635

This paper provides a description of the processes applied within the Aqueous Discharge Abatement Plant (ADAP) at Bradwell nuclear power plant in the UK. This incorporates the Fuel Element Debris (FED) abatement plant and the Modular Active Effluent Treatment Plant (MAETP). These plants are housed in adjacent, but separate, structures and are inter-linked and share common services and control systems. The FED abatement plant, which has a shorter mission than MAETP, can be removed for decommissioning or redeployment without any impact to MAETP operation. ADAP treats aqueous waste streams generated during the ongoing decontamination and decommissioning (D and D) operations for release from the Bradwell Power Station. The plant is designed to receive and treat two major classes of liquids: 1. Slightly contaminated water from various D and D sources and collected rainwater from the power station, referred to as Aqueous Effluent (AE). 2. Dissolved fuel element debris solution. This comprises of contaminated magnesium alloy (generated during the stripping of external structures from spent Magnox fuel elements prior to shipment for reprocessing) which has been dissolved in nitric acid. All received wastes are treated to remove heavy metals and radioactive constituents prior to isolation, sampling, verification, and ultimately release to the Blackwater Estuary. The treatment consists of multiple processes including precipitation, filtration, adsorption and ion exchange carefully designed to remove targeted radionuclides and heavy metals. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Use of advanced optimization algorithms for the design of critical experiments

The need for validating molybdenum and rhodium cross sections in the thermal energy range has arisen for many years for reprocessing activities and burnup credit calculations. An Integral Experimental Request (IER) sheet was submitted by IRSN to the NCSP (Nuclear Criticality Safety Program) in 2015. A preliminary design was therefore proposed for review. In order to define experiments that meet the requirements and that exhibit optimized sensitivities of k{sub eff} to the capture cross sections of {sup 95}Mo and {sup 103}Rh, advanced algorithms of the PROMETHEE workbench, developed at IRSN, were used. The methodology as well as the main results are presented in this paper, which focuses only on the molybdenum experiments design. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗