Search

The development of sustainable advanced nuclear fuel cycles is a long-term goal of the Office of Nuclear Energy’s (DOE-NE) Fuel Cycle Technologies program. The Material Protection, Accounting, and Control Technologies (MPACT) campaign is supporting research and development (R&D) of advanced instrumentation, analysis tools, and integration methodologies to meet this goal. This advanced R&D is intended to facilitate safeguards and security by design of fuel cycle facilities. The lab-scale demonstration of a virtual facility, distributed test bed, that connects the individual tools being developed at National Laboratories and university research establishments, is a key program milestone for 2020. These tools will consist of instrumentation and devices as well as computer software for modeling. To aid in framing its long-term goal, during FY16, a modeling and simulation roadmap is being developed for three major areas of investigation: (1) radiation transport and sensors, (2) process and chemical models, and (3) shock physics and assessments. For each area, current modeling approaches are described, and gaps and needs are identified.

The first wall armor of the inertial confinement fusion reactor chambers must withstand high temperatures and significant radiation damage from target debris and neutrons. The resilience of multiple materials to one component of the target debris has been investigated using energetic (20–40 keV) helium ions generated in the inertial electrostatic confinement device at the University of Wisconsin. The materials studied include: single-crystalline, and polycrystalline tungsten, tungsten-coated tantalum-carbide ‘foams’, tungsten–rhenium alloy, silicon carbide, carbon–carbon velvet, and tungsten-coated carbon–carbon velvet. Steady-state irradiation temperatures ranged from 750 to 1250 °C with helium fluences between 5 × 1017 and 1 × 1020 He+/cm2. The crystalline, rhenium alloyed, carbide foam, and powder metallurgical tungsten specimens each experienced extensive pore formation after He+ irradiation. Flaking and pore formation occurred on silicon carbide samples. Individual fibers of carbon–carbon velvet specimens sustained erosion and corrugation, in addition to the roughening and rupturing of tungsten coatings after helium ion implantation.

Energy demand and GDP per capita are strongly correlated, while public concern over the role of energy in climate change is growing. Nuclear power plants produce 16% of world electricity demands without greenhouse gases. Generation-IV advanced nuclear energy systems are being designed to be safe and economical. Minimizing the handling and storage of nuclear waste is important. NIF and ITER are bringing sustainable fusion energy closer, but a significant gap in fusion technology development remains. Fusion–fission hybrids could be a synergistic step to a pure fusion economy and act as a technology bridge. We discuss how a pulsed power-driven Z-pinch hybrid system producing only 20 MW of fusion yield can drive a sub-critical transuranic blanket that transmutes 1280 kg of actinide wastes per year and produces 3000 MW. These results are applicable to other inertial and magnetic fusion energy systems. A hybrid system could be introduced somewhat sooner because of the modest fusion yield requirements and can provide both a safe alternative to fast reactors for nuclear waste transmutation and a maturation path for fusion technology. The development and demonstration of advanced materials that withstand high-temperature, high-irradiation environments is a fundamental technology issue that is common to both fusion–fission hybrids and Generation-IV reactors.

Efficient burn up of minor actinides is one of the most promising alternatives for minimizing waste in advanced nuclear fuel cycles. This work examines the concept of employing Z-pinch driven fusion source in a sub-critical transmutation reactor designed to burn up actinides and generate constant power. Its fuel cycle is designed to allow on-line fission product removal and fuel replenishment. The variation of the actinide inventory is an essential quantity used to calculate the energy multiplications and neutron spectrum, as well as to design an appropriate reactivity control mechanism. In this paper we develop a method to calculate time-dependent isotopic distributions, fuel feeding rate and fission product removal rate necessary to obtain a constant power level. The calculation is performed by using both MCise, a Monte Carlo isotopic inventory code, and MCNP5. An important feature of MCise for this system is the ability to simulate the on-line removal of fission products from the actinide mixture. In addition to reporting the actinide inventory and burn rates, the impact of the actinide inventory on the fission/fusion energy multiplication will be examined.

Sandia National Laboratories has initiated a scoping level design of a sub-critical transmutation reactor driven by Z-Pinch fusion. The baseline design is able to burn up 1,280 kg of actinides per year while at the same time producing 3,000 MW th . The fusion driver required for this application is 20 MW, or a 200 MJ target fired once every 10 seconds. This paper discusses how a fusion actinide burner can fit into the nuclear fuel cycle.

The initiation of the Global Nuclear Energy Partnership includes nuclear-based transmutation devices to recycle the spent fuel. Fusion can offer an alternative to the use of fast reactors for the transmutation of actinides. At a modest fusion power of 20 MW, a Z-Pinch driven sub-critical blanket can burn actinides and produce power. Several engineering issues have been examined: the effect of the sub-critical blanket and its internal fission neutrons on tritium breeding, radiation damage to structure, energy deposition and extraction, and chamber activation. Our initial assessment indicates the Z-Pinch could be an attractive option for burning actinides, but special attention should be paid to the challenging engineering issues.

The D-3He fusion reaction has been used to produce medical radioisotopes using the University of Wisconsin Inertial Electrostatic Confinement (IEC) Fusion Device. The high-energy 14.7 MeV proton ge...

In Inertial Electrostatic Confinement (IEC) devices, a voltage difference between concentric, nearly transparent spherical grids accelerates ions to fusion-relevant velocities. The University of Wisconsin (UW) operates two IEC devices: a cylindrical aluminum chamber and a spherical, water-cooled, stainless-steel chamber, with a power supply capable of 75 mA and 200 kV. The research program aims to generate fusion reaction products for various applications, including protons for creating radioisotopes for nuclear medicine and neutrons for detecting clandestine materials. Most IEC devices worldwide, including the UW devices, presently operate primarily in a pressure range (1-10 mtorr) that allows ions to make only a few passes through the core before they charge exchange and lose substantial energy or they collide with cathode grid wires. It is believed that fusion rates can be raised by operating at a pressure where neutral gas does not impede ion flow, and a helicon ion source has been developed t...

The Z-Pinch Power Plant (ZP3) uses the results from Sandia National Laboratories' Z accelerator in a power plant application to generate energy pulses using inertial confinement fusion. A collaborative project has been initiated by Sandia to investigate the scientific principles of a power generation system. Research is underway to investigate the use of recyclable transmission lines to directly connect the wire array and the hohlraum to the pulsed power driver. The resulting power plant will require an intense on-site manufacturing system to rebuild the transmission lines, wire arrays and hohlraums at a rate of 0.1 Hz per power unit. By recycling virtually all of the materials, the system is expected to be economically competitive with other power generation technologies. Current research is investigating the available approaches to manufacturing and determining the cost effectiveness of the alternatives. This paper examines the various options available for manufacturing and development requirements leading to a Proof-of-Principle experiment to demonstrate the technology.

The high-energy 14.7 MeV protons generated from the D- 3 He fusion reaction can be used to produce medical radioisotopes. Steady-state D 3 He operation is possible using Inertial Electrostatic Confinement (IEC); however, the location of the reactions must be known to use them effectively for isotope production. In the University of Wisconsin IEC Device, it has been found that as much as 2/3 of the total D- 3 He reaction rate can be due to embedded fusion reactions, reactions occurring within the cathode due to ion implantation. Therefore, the cathode surface sees a large, high-energy proton flux. Using a solid molybdenum cathode, and taking advantage of the embedded reactions, about I nCi of the medical isotope 94m Tc was created via 94 Mo(p,n) 94m Tc in a proof of principle experiment. This represents the first time the IEC concept has been used to produce a radioisotope using D- 3 He fusion.

A major effort to find near-term, non-electric applications of fusion energy has shown that the production of radioisotopes is attractive. The use of the D3He fusion reaction to produce Positron Em...

This paper describes a proof of principle experiment to produce 13N using an inertial electrostatic confinement (IEC) fusion device. This radioisotope is often used in positron emission tomography ...

University of Wisconsin (UW) inertial electrostatic confinement (IEC) facility has made significant progress since 2000. The operating voltage has doubled to 160 kV. The neutron production rate has increased by a factor of 2, from 4.9 x 10{sup 7}/s to 1.1 x 10{sup 8}s{sup -1}. The D-{sup 3}He proton production rate has increased by, a factor of over 40. In addition new diagnostics have been developed, including a method to determine the spatial distribution of fusion reactions A new water cooled stainless steel chamber for higher power and lower pressure has been put into operation. Medical isotopes have been produced in an IEC device for the first time.

This report gives an overview of expected design characteristics, concepts, and procedures for small modular reactors. The purpose of this report is to provide those who are interested in reducing the cost and improving the safety of advanced nuclear power plants with a generic design that possesses enough detail in a non-sensitive manner to give merit to their conclusions. The report is focused on light water reactor technology, but does add details on what could be different in a more advanced design (see Appendix). Numerous reactor and facility concepts were used for inspiration (documented in the bibliography). The final design described here is conceptual and does not reflect any proposed concept or sub-systems, thus any details given here are only relevant within this report. This report does not include any design or engineering calculations.

Advanced nuclear fuel cycle concept is interested in reducing separations to a simplified, one-step process if possible. This will benefit from the development of a one-step universal getter and sequestration material so as a simplified, universal waste form was proposed in this project. We have developed a technique combining a modified sol-gel chemistry and electrospinning for producing ultra-porous ceramic nanofiber membranes with controllable diameters and porous structures as the separation/sequestration materials. These ceramic nanofiber materials have been determined to have high porosity, permeability, loading capacity, and stability in extreme conditions. These porous fiber membranes were functionalized with silver nanoparticles and nanocrystal metal organic frameworks (MOFs) to introduce specific sites to capture gas species that are released during spent nuclear fuel reprocessing. Encapsulation into a durable waste form of ceramic composition was also demonstrated.

Nuclear fuel reprocessing plants contain a wealth of plant monitoring data including material measurements, process monitoring, administrative procedures, and physical protection elements. Future facilities are moving in the direction of highly-integrated plant monitoring systems that make efficient use of the plant data to improve monitoring and reduce costs. The Separations and Safeguards Performance Model (SSPM) is an analysis tool that is used for modeling advanced monitoring systems and to determine system response under diversion scenarios. This report both describes the architecture for such a future monitoring system and present results under various diversion scenarios. Improvements made in the past year include the development of statistical tests for detecting material loss, the integration of material balance alarms to improve physical protection, and the integration of administrative procedures. The SSPM has been used to demonstrate how advanced instrumentation (as developed in the Material Protection, Accounting, and Control Technologies campaign) can benefit the overall safeguards system as well as how all instrumentation is tied into the physical protection system. This concept has the potential to greatly improve the probability of detection for both abrupt and protracted diversion of nuclear material.

The future of reprocessing in the United States is strongly driven by plant economics. With increasing safeguards, security, and safety requirements, future plant monitoring systems must be able to demonstrate more efficient operations while improving the current state of the art. The goal of this work was to design and examine the incorporation of advanced plant monitoring technologies into safeguards systems with attention to the burden on the operator. The technologies examined include micro-fluidic sampling for more rapid analytical measurements and spectroscopy-based techniques for on-line process monitoring. The Separations and Safeguards Performance Model was used to design the layout and test the effect of adding these technologies to reprocessing. The results here show that both technologies fill key gaps in existing materials accountability that provide detection of diversion events that may not be detected in a timely manner in existing plants. The plant architecture and results under diversion scenarios are described. As a tangent to this work, both the AMUSE and SEPHIS solvent extraction codes were examined for integration in the model to improve the reality of diversion scenarios. The AMUSE integration was found to be the most successful and provided useful results. The SEPHIS integration is still a work in progress and may provide an alternative option.

Small Module Reactors (SMRs) face a number of licensing issues due to the fact that existing regulations were designed for large units. The move toward smaller cores, more reliance on passive safety, and modular construction will require new research to meet existing regulations and possibly regulatory change that would be more appropriate to and cost effective for this technology. The Department of Energy is funding a number of research projects to address SMR licensing issues, including both regulatory framework and design-related issues. Near term priorities include Emergency Planning Zone (EPZ) sizing, operations & staffing, and physical security integration. The recent accident in Japan only heightens the need for thorough analysis of these issues. The purpose of these activities is to provide research support to assist SMR vendors with licensing and to assist the Nuclear Regulatory Commission (NRC) in any data needs that might be required for these unique designs. These research activities will be described with attention to how they will address the SMR licensing needs.Copyright © 2011 by ASME

Research and development of advanced reprocessing plant designs can greatly benefit from the development of a reprocessing plant model capable of transient solvent extraction chemistry. This type of model can be used to optimize the operations of a plant as well as the designs for safeguards, security, and safety. Previous work has integrated a transient solvent extraction simulation module, based on the Solvent Extraction Process Having Interaction Solutes (SEPHIS) code developed at Oak Ridge National Laboratory, with the Separations and Safeguards Performance Model (SSPM) developed at Sandia National Laboratory, as a first step toward creating a more versatile design and evaluation tool. The goal of this work was to strengthen the integration by linking more variables between the two codes. The results from this integrated model show expected operational performance through plant transients. Additionally, ORIGEN source term files were integrated into the SSPM to provide concentrations, radioactivity, neutron emission rate, and thermal power data for various spent fuels. This data was used to generate measurement blocks that can determine the radioactivity, neutron emission rate, or thermal power of any stream or vessel in the plant model. This work examined how the code could be expanded to integrate other separation stepsmore » and benchmark the results to other data. Recommendations for future work will be presented.« less

The Separations and Safeguards Performance Model is a reprocessing plant model that has been developed for safeguards analyses of future plant designs. The model has been modified to integrate bulk process monitoring data with traditional plutonium inventory balances to evaluate potential advanced safeguards systems. Taking advantage of the wealth of operator data such as flow rates and mass balances of bulk material, the timeliness of detection of material loss was shown to improve considerably. Four diversion cases were tested including both abrupt and protracted diversions at early and late times in the run. The first three cases indicated alarms before half of a significant quantity of material was removed. The buildup of error over time prevented detection in the case of a protracted diversion late in the run. Some issues related to the alarm conditions and bias correction will need to be addressed in future work. This work both demonstrates the use of the model for performing diversion scenario analyses and for testing advanced safeguards system designs.

A past difficulty in safeguards design for reprocessing plants is that no code existed for analysis and evaluation of the design. A number of codes have been developed in the past, but many are dated, and no single code is able to cover all aspects of materials accountancy, process monitoring, and diversion scenario analysis. The purpose of this work was to integrate a transient solvent extraction simulation module developed at Oak Ridge National Laboratory, with the SSPM Separations and Safeguards Performance Model, developed at Sandia National Laboratory, as a first step toward creating a more versatile design and evaluation tool. The SSPM was designed for materials accountancy and process monitoring analyses, but previous versions of the code have included limited detail on the chemical processes, including chemical separations. The transient solvent extraction model is based on the ORNL SEPHIS code approach to consider solute build up in a bank of contactors in the PUREX process. Combined, these capabilities yield a much more robust transient separations and safeguards model for evaluating safeguards system design. This coupling and the initial results are presented. In addition, some observations toward further enhancement of separations and safeguards modeling based on this effort are provided, including: items to be addressed in integrating legacy codes, additional improvements needed for a fully functional solvent extraction module, and recommendations for future integration of other chemical process modules.

Traditional safeguards and security design for fuel cycle facilities is done separately and after the facility design is near completion. This can result in higher costs due to retrofits and redundant use of data. Future facilities will incorporate safeguards and security early in the design process and integrate the systems to make better use of plant data and strengthen both systems. The purpose of this project was to evaluate the integration of materials control and accounting (MC&A) measurements with physical security design for a nuclear reprocessing plant. Locations throughout the plant where data overlap occurs or where MC&A data could be a benefit were identified. This mapping is presented along with the methodology for including the additional data in existing probabilistic assessments to evaluate safeguards and security systems designs.

Next generation nuclear fuel cycle facilities will face strict requirements on security and safeguards of nuclear material. These requirements can result in expensive facilities. The purpose of this project was to investigate how to incorporate safeguards and security into one plant monitoring system early in the design process to take better advantage of all plant process data, to improve confidence in the operation of the plant, and to optimize costs. An existing reprocessing plant materials accountancy model was examined for use in evaluating integration of safeguards (both domestic and international) and security. International safeguards require independent, secure, and authenticated measurements for materials accountability--it may be best to design stand-alone systems in addition to domestic safeguards instrumentation to minimize impact on operations. In some cases, joint-use equipment may be appropriate. Existing domestic materials accountancy instrumentation can be used in conjunction with other monitoring equipment for plant security as well as through the use of material assurance indicators, a new metric for material control that is under development. Future efforts will take the results of this work to demonstrate integration on the reprocessing plant model.

The reprocessing and recycling of spent nuclear fuel can benefit the nuclear fuel cycle by destroying actinides or extending fissionable resources if uranium supplies become limited. The purpose of this study was to assess reprocessing and recycling in both fast and thermal reactors to determine the effectiveness for actinide destruction and resource utilization. Fast reactor recycling will reduce both the mass and heat load of actinides by a factor of 2, but only after 3 recycles and many decades. Thermal reactor recycling is similarly effective for reducing actinide mass, but the heat load will increase by a factor of 2. Economically recoverable reserves of uranium are estimated to sustain the current global fleet for the next 100 years, and undiscovered reserves and lower quality ores are estimated to contain twice the amount of economically recoverable reserves--which delays the concern of resource utilization for many decades. Economic analysis reveals that reprocessed plutonium will become competitive only when uranium prices rise to about %24360 per kg. Alternative uranium sources are estimated to be competitive well below that price. Decisions regarding the development of a near term commercial-scale reprocessing fuel cycle must partially take into account the effectiveness of reactors for actnides destructionmore » and the time scale for when uranium supplies may become limited. Long-term research and development is recommended in order to make more dramatic improvements in actinide destruction and cost reductions for advanced fuel cycle technologies.The original scope of this work was to optimize an advanced fuel cycle using a tool that couples a reprocessing plant simulation model with a depletion analysis code. Due to funding and time constraints of the late start LDRD process and a lack of support for follow-on work, the project focused instead on a comparison of different reprocessing and recycling options. This optimization study led to new insight into the fuel cycle. AcknowledgementThe authors would like to acknowledge the support of Laboratory Directed Research and Development Project 125862 for funding this research.« less

The resurgence of interest in reprocessing in the United States with the Global Nuclear Energy Partnership has led to a renewed look at technologies for transmuting nuclear waste. Sandia National Laboratories has been investigating the use of a Z-Pinch fusion driver to burn actinide waste in a sub-critical reactor. The baseline design has been modified to solve some of the engineering issues that were identified in the first year of work, including neutron damage and fuel heating. An on-line control feature was added to the reactor to maintain a constant neutron multiplication with time. The transmutation modeling effort has been optimized to produce more accurate results. In addition, more attention was focused on the integration of this burner option within the fuel cycle including an investigation of overall costs. This report presents the updated reactor design, which is able to burn 1320 kg of actinides per year while producing 3,000 MWth.

Due to increasing concerns over the buildup of long-lived transuranic isotopes in spent nuclear fuel waste, attention has been given in recent years to technologies that can burn up these species. The separation and transmutation of transuranics is part of a solution to decreasing the volume and heat load of nuclear waste significantly to increase the repository capacity. A fusion neutron source can be used for transmutation as an alternative to fast reactor systems. Sandia National Laboratories is investigating the use of a Z-Pinch fusion driver for this application. This report summarizes the initial design and engineering issues of this ''In-Zinerator'' concept. Relatively modest fusion requirements on the order of 20 MW can be used to drive a sub-critical, actinide-bearing, fluid blanket. The fluid fuel eliminates the need for expensive fuel fabrication and allows for continuous refueling and removal of fission products. This reactor has the capability of burning up 1,280 kg of actinides per year while at the same time producing 3,000 MWth. The report discusses the baseline design, engineering issues, modeling results, safety issues, and fuel cycle impact.

This report summarizes the work conducted for the Z-inertial fusion energy (Z-IFE) late start Laboratory Directed Research Project. A major area of focus was on creating a roadmap to a z-pinch driven fusion power plant. The roadmap ties ZIFE into the Global Nuclear Energy Partnership (GNEP) initiative through the use of high energy fusion neutrons to burn the actinides of spent fuel waste. Transmutation presents a near term use for Z-IFE technology and will aid in paving the path to fusion energy. The work this year continued to develop the science and engineering needed to support the Z-IFE roadmap. This included plant system and driver cost estimates, recyclable transmission line studies, flibe characterization, reaction chamber design, and shock mitigation techniques.

The Z-Pinch fusion experiment at Sandia National Laboratories has been making significant progress in developing a high-energy fusion neutron source. This source has the potential to be used for the transmutation of nuclear waste. The goal of this research was to do a scoping-level design of a fusion-based transmuter to determine potential transmutation rates along with the fusion yield requirements. Two ''In-Zinerator'' designs have been developed to transmute the long-lived actinides that dominate the heat production in spent fuel. The first design burns up all transuranics (TRU) in spent fuel (Np, Pu, Am, Cm), and the second is focused only on burning up Am and Cm. The TRU In-Zinerator is designed for a fuel cycle requiring burners to get rid of all the TRU with no light water reactor (LWR) recycle. The Am/Cm In-Zinerator is designed for a fuel cycle with Np/Pu recycling in LWRs. Both types of In-Zinerators operate with a moderate fusion source driving a sub-critical actinide blanket. The neutron multiplication is 30, so a great deal of energy is produced in the blanket. With the design goal of generating 3,000 MW{sub th}, about 1,200 kg/yr of actinides can be destroyed in each In-Zinerator. Each TRU In-Zinerator willmore » require a 20 MW fusion source, and it will take a total of 20 units (each producing 3,000 MWth) to burn up the TRU as fast as the current LWR fleet can produce it. Each Am/Cm In-Zinerator will require a 24 MW fusion source, and it will take a total of 2 units to burn up the Am/Cm as fast as the current LWR fleet can produce it. The necessary fusion yield could be achieved using a 200-240 MJ target fired once every 10 seconds.« less

Recent interest in reprocessing nuclear fuel in the U.S. has led to advanced separations processes that employ continuous processing and multiple extraction steps. These advanced plants will need to be designed with state-of-the-art instrumentation for materials accountancy and control. This research examines the current and upcoming instrumentation for nuclear materials accountancy for those most suited to the reprocessing environment. Though this topic has received attention time and again in the past, new technologies and changing world conditions require a renewed look and this subject. The needs for the advanced UREX+ separations concept are first identified, and then a literature review of current and upcoming measuring techniques is presented. The report concludes with a preliminary list of recommended instruments and measurement locations.