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DOE OSTI2014

Nano-Scale Fission Product Phases in an Irradiated U-7Mo Alloy Nuclear Fuel

Irradiated nuclear fuel is a very difficult material to characterize. Due to the large radiation fields associated with these materials, they are hard to handle and typically have to be contained in large hot cells. Even the equipment used for performing characterization is housed in hot cells or shielded glove boxes. The result is not only a limitation in the techniques that can be employed for characterization, but also a limitation in the size of features that can be resolved The most standard characterization techniques include light optical metallography (WM), scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). These techniques are applied to samples that are typically prepared using grinding and polishing approaches that will always generate some mechanical damage on the sample surface. As a result, when performing SEM analysis, for example, the analysis is limited by the quality of the sample surface that can be prepared. However, a new approach for characterizing irradiated nuclear fuel has recently been developed at the Idaho National Laboratory (INL) in Idaho Falls, Idaho. It allows for a dramatic improvement in the quality of characterization that can be performed when using an instrument like an SEM. This new approach uses a dual-beam scanning microscope, where one of the beams isa focused ion beam (FIB), which can be used to generate specimens of irradiated fuel (-10µm x 10µm) for microstructural characterization, and the other beam is the electron beam of an SEM. One significant benefit of this approach is that the specimen surface being characterized has received much less damage (and smearing) than is caused by the more traditional approaches, which enables the imaging of nanometer sized microstructural features in the SEM. The process details are for an irradiated low-enriched uranium (LEU) U-Mo alloy fuel Another type of irradiated fuel that has been characterized using this technique is a mixed oxide fuel.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2020

Production of Cf-252 and other transplutonium isotopes at Oak Ridge National Laboratory

In 1957 Glenn T. Seaborg conceived and advocated for the construction of the High Flux Isotope Reactor (HFIR) and the Transuranium Processing Plant (since then renamed the Radiochemical Engineering Development Center, or REDC) at Oak Ridge National Laboratory. There, heavily shielded hot cells, glove boxes, and laboratories allow recovery of transuranium elements produced in substantial quantities. Seaborg’s vision of HFIR and REDC producing milligram quantities of berkelium, californium, and einsteinium has been fulfilled beginning in 1966 through May 2019 with 78 production campaigns yielding a cumulative totals of 1.2 g of 249 Bk, 10.2 g of 252 Cf, 39 mg of 253 Es, and 15 pg of 257 Fm. Notably, 252 Cf is a neutron source used in many industrial applications including oil exploration; process control systems for the cement industry, coal analysis, and power production; sources to start nuclear reactors and perform nondestructive materials analyses; homeland security and national defense detection devices; and medical research. Isotopes made available through transplutonium production at HFIR/REDC have enabled scientists to study the nuclear properties and reactions, chemical properties, optical properties, and solid-state properties of transplutonium elements. Long-lived isotopes have served as targets in heavy ion accelerators to produce heavier elements leading to the discovery of 104 Rf, 105 Db, 106 Sg, 113 Nh, 114 Fl, 115 Mc, 116 Lv, 117 Ts, and 118 Og. This paper reviews the evolution of the processing flowsheets to produce, separate, and purify transplutonium isotopes, which have evolved over 50 years of operation at HFIR and REDC, and summarizes directions of future work to improve the efficiency of the production operations.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

DOE OSTI2020

Demonstration of Integrated PostIrradiation Process Steps forMultikilogram Amounts of Low- and High-Burnup Used Nuclear Fuels

sponsored research and development (R&D) on the advanced, closed nuclear fuel cycle, including post-irradiation processing of used fuels, recovery of separated components, and preparation of recycle nuclear fuels. During the period 2007–2010, kilogram-scale demonstrations of the integrated processing steps were performed for actual light water reactor (LWR) used nuclear fuels (UNF). These integrated processing demonstrations were called “the Coupled-End-to-End” (CETE) campaigns and were associated with the Global Nuclear Energy Partnership program, which ran concurrently. The demonstrations were carried out in the shielded hot cells and associated gloveboxes located in the Irradiated Fuels Examination Laboratory (IFEL) and the Radiochemical Engineering Development Center (REDC) at the Oak Ridge National Laboratory (ORNL). Limited circulation program reports and a few technical papers were issued. The subject document provides a comprehensive summary of results, technical comparisons, and conclusions obtained from the demonstration campaigns and subsequent associated R&D.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2021

Monitoring Radiochemical Processing Streams for the 238 Pu Supply Program with Process Pulse II

Oak Ridge National Laboratory (ORNL) is developing advanced spectroscopic and real-time monitoring capabilities to improve the timeliness of analytical measurements and process decisions for the 238Pu Supply Program. Reducing the time, resources, and costs associated with each production campaign is critical because overlapping campaigns will be required to meet the production goals of the National Aeronautics and Space Administration. Real-time, in situ analytical measurements in the heavily shielded hot cells at the Radiochemical Engineering Development Center (REDC) will allow for rapid process information feedback and operational benefits that help the 238Pu supply program scale-up production efforts. Noteworthy steps were taken during Campaign 5 to establish the ability to monitor processing streams in real time with spectrophotometry and a commercially available online monitoring software called The Unscrambler X Process Pulse II (PP) multivariate statistical process monitoring system by Camo Analytics (version 5.60). PP automates univariate-type calculations within the software itself and executes multivariate models built using The Unscrambler X (version 10.4 or newer). The Unscrambler is a commercially available data analysis software made by the same company. PP is composed of easy-to-use-tools for all personnel, including data scientists and technicians. The software can be used to plot analyte concentration profiles, spectral data, and other process variables in real time. All process data are represented in a single view with interactive charts useful for viewing how a process evolves over time.

07 ISOTOPE AND RADIATION SOURCES↗

NASA NTRS2000

Facility Designed and Built to Investigate the Combined Effects of Contaminant and Atomic Oxygen on a Light-Transmitting Surface

A need exists to investigate changes in the transparency of a light-transmitting surface during simultaneous exposure to a contaminant and an atomic oxygen (AO) flux. This mechanism may be responsible for the degradation of the light-transmitting surfaces of both photovoltaic cells and photodiodes currently in use on many low-Earth-orbit spacecraft. To address this need, researchers from the Electro-Physics Branch of the NASA Glenn Research Center at Lewis Field built such a test system within their AO beam facility. This facility produces an effective AO flux of 1.4 10(exp 16) atoms/sq cm/sec and contains a three-axis positioning system that provides the motion capability necessary for test operations. During testing, a target surface is held directly within the AO beam and close to two contaminant effusion cells. The effusion cells are shielded from the AO beam, and the outgassing contaminant is constrained to move across the target surface when heat is applied to either of the reservoirs. A light source is periodically moved over the target surface, and the transmitted light intensity is checked with a photodiode located below the target. This light source is also periodically checked with a separate photodiode, which is protected from contamination and AO exposure, to allow adjustments necessary to maintain a consistent light intensity.

Sechkar, Edward A.↗

DOE OSTI2013

Casting evaluation of U-Zr alloy system fuel slug for SFR prepared by injection casting method

Metal fuel slugs of U-Pu-Zr alloys for Sodium-cooled Fast Reactor (SFR) have conventionally been fabricated by a vacuum injection casting method. Recently, management of minor actinides (MA) became an important issue because direct disposal of the long-lived MA can be a long-term burden for a tentative repository up to several hundreds of thousand years. In order to recycle transuranic elements (TRU) retained in spent nuclear fuel, remote fabrication capability in a shielded hot cell should be prepared. Moreover, generation of long-lived radioactive wastes and loss of volatile species should be minimized during the recycled fuel fabrication step. In order to prevent the evaporation of volatile elements such as Am, alternative fabrication methods of metal fuel slugs have been studied applying gravity casting, and improved injection casting in KAERI, including melting under inert atmosphere. And then, metal fuel slugs were examined with casting soundness, density, chemical analysis, particle size distribution and microstructural characteristics. Based on these results there is a high level of confidence that Am losses will also be effectively controlled by application of a modest amount of overpressure. A surrogate fuel slug was generally soundly cast by improved injection casting method, melted fuel material under inert atmosphere.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2016

Treatment of LLW Components for Waste Minimization and Recycling - 16258

The Studsvik Melting Facility has been in operation for almost 30 years. Many turbines, heat exchangers and other retired components, pipes, structures have been treated in the facility during those years. The ambition of all projects is to minimize the waste volumes for final disposal and to maximize the amount of material that can be recycled. Another objective, respecting ALARA, is to keep dose exposition to the personnel at very low levels. The overall concept comprises the whole sequence of preparations from road and sea transports, the management of the metallic LLW by segmentation, decontamination and sorting using specially devised tools and shielded treatment cell, to the decision criteria for recycling of the metals, radiological analyses and conditioning of the residual waste into a final form suitable for customer-related disposal. The records show that the amount of material possible for conditional clearance to open market after treatment is between 95 - 97 % on weight for falling metallic scrap. For large components there is a larger span and especially for heat exchangers. This paper describes the Studsvik technical concept and experience related to treatment of metals from the program for modernization and power upgrade of the Swedish nuclear power plants. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2018

Adaptation of Commercially Available Robots for Conditioning and Packaging ILW at Sellafield - 18282

The Legacy Ponds and Silos at Sellafield site contain some of the most hazardous Intermediate Level Waste (ILW) in the UK. As part of a multi-billion pound decommissioning programme, this waste will be retrieved and transported across the site for conditioning and packaging in the Box Encapsulation Plant (BEP). Current plans are to commence plant active commissioning in 2022, which will represent a major milestone in the UK nuclear decommissioning programme. Within the plant, skips of waste will be transferred from the shielded transport package into standard 3 cubic metre ILW containers. Waste from the Pile Fuel Storage Pond and First Generation Magnox Storage Pond will be immobilised in cementitious grout before being transferred to an adjacent store. Waste from the Magnox Swarf Storage Silo will not be immobilised in grout, but will be packaged, providing multi-barrier containment. During the concept design, the project team selected commercially available robots as the most viable technology for carrying out the numerous dexterous and repetitive tasks involved in characterising, conditioning and packaging the waste within the shielded 'hot' cells. Significant technical challenges had to be overcome during the design to adapt a commercially available robot for use within a high radiation / high contamination environment, where human access is not safe even for short periods of time. These challenges included: - Designing robot assemblies that could be retrofitted into the existing cell structure that was constructed as part of an earlier project but never completed; - Designing robot assemblies that could be recovered to their 'transport' position without requiring manual intervention; - Designing robot assemblies that could be remotely removed and replaced with new ones if they failed part way through the plant operational life; - Designing through-wall service and power connections that allow maintenance and recovery; - Designing control systems and human-machine interfaces that enable both manual and automated operation of the robot, whilst avoiding collisions with the in-cell cranes and other in cell furniture; - Assessing the radiation tolerance of all items. Bespoke computer simulations and full-scale development trials have been carried out, using non-active test materials, in order to demonstrate the Technology Readiness Level (TRL) required by Sellafield Limited (SL) at each stage of the project [1]. The results of these trials have been recorded in both video and written form so that they can form part of the project's Knowledge Management database. Detailed designs and specifications for the robot assemblies have been updated to incorporate the recommendations from the development trials. Procurement and manufacture of robot assemblies has already commenced to deliver two waste handling robots, two waste container lidding / swabbing robots and associated critical spares. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2023

Acoustic Monitoring of Pyroprocessing Equipment

This paper provides an introduction to using acoustic monitoring to advance detection techniques for pyroprocessing in support of nuclear safeguards and non-proliferation. The usage of free air acoustic monitoring has been previously demonstrated at Idaho National Laboratory (INL) facilities such as the Advanced Test Reactor and the National Security Test Range. However, the proposed work revolves around a new deployment environment, the Fuel Conditioning Facility, that brings forward several questions regarding the performance of the technology in non-free air media. The confinement of the pyroprocessing equipment to a heavily shielded hot cell, the atmosphere of the hot cell containing argon gas, and the radiation dose inside the hot cell are all new environments for acoustic monitoring. To our knowledge, acoustic measurements have not been completed in such an environment before. This offers a new opportunity to study not only the acoustic signatures of the equipment inside of the hot cell, but also the propagation of the signals through the hot cell and at distances away from their origination. The objective of this paper is to explain the planned instruments to monitor the Fuel Conditioning Facility in order to evaluate acoustic signals emitted from equipment during various stages of operation. Identifying these signals can potentially enable the identification of specific pieces of equipment used in pyroprocessing and produce information of their operational status. If successful, this type of monitoring could offer a new method to aid in safeguards and proliferation detection of pyroprocessing activities.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗

DOE OSTI2017

Preliminary Analysis of Facility Design for Pyro-processing Safeguardability

The deployment of advanced nuclear energy systems can assure sustainable energy use worldwide. For some of these systems, nuclear fuel will be fabricated in remotely-handled facilities in which batch-type processing will occur in heavily-shielded hot cells. Because special nuclear material is in both different physical and chemical form than that of the contemporary fuel cycle, new challenges have arisen in terms of safeguards, safety, and security, integrated with facility design; i.e., safeguardability. There is a need to develop models that can quantitatively assess safeguardability from a design-driven perspective. Previously, the first build of a material throughput model was established using discrete event simulation (DES) for the fuel fabrication process. Results showed that the DES model potentially can detect diversion attempts. This paper continues the study by further developing the the model. We test the use of the probability of the false alarm; i.e., the Type I error, as a metric for safeguardability assessment. Initiating events leading to a false alarm arise from aspects of safeguards, safety, and security. Different conceptual facility designs could exhibit different frequencies for the Type I error, and this could provide a measure of the safeguardability of each design. A quantitative assessment for safeguardable facility designs has not been developed in this manner. Much of the research into safeguardability has been qualitative. Engineering design approaches for a safeguardable facility are now needed. As there are not accepted metrics for safeguardability assessment, our motivation is to develop this design facet of safeguardability further.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2025

Seismoacoustic Monitoring of Pyroprocessing Equipment

With the projected increase in world nuclear capacity comes the hurdle of spent nuclear fuel. Pyroprocessing is one method to process irradiated fuel by using high temperatures and electrochemical steps to separate radioactive components. High temperatures, high radiation levels, and equipment confined to a heavily shielded hot cell are a few of the challenges introduced regarding safeguards for pyroprocessing. The first stage of the process utilizes an element chopper to cut irradiated fuel into smaller pieces, offering the potential to identify equipment operation through seismoacoustic monitoring. Eleven seismic and infrasound sensors were deployed at various locations and distances near a pyroprocessing hot cell to evaluate signals emitted from the chopper. Signals were processed using short-time Fourier transforms and manually scanned to locate chopping events. Operator logs were then collected for a ground truth comparison. Results indicate that both infrasound and seismic signals offer the ability to accurately measure this stage of pyroprocessing, though seismic signals are more prominent. Sensor locations are also evaluated to determine where the signal is detectable. This type of monitoring offers a method to aid in safeguards and proliferation detection by validating a pyroprocessing facility’s schedule and identifying activity that does not align with records.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

NASA NTRS1996

Shielding against galactic cosmic rays

Ions of galactic origin are modified but not attenuated by the presence of shielding materials. Indeed, the number of particles and the absorbed energy behind most shield materials increases as a function of shield thickness. The modification of the galactic cosmic ray composition upon interaction with shielding is the only effective means of providing astronaut protection. This modification is intimately conntected with the shield transport porperties and is a strong function of shield composition. The systematic behavior of the shield properites in terms of microscopic energy absorption events will be discussed. The shield effectiveness is examined with respect to convectional protection practice and in terms of a biological endpoint: the efficiency for reduction of the probability of transformation of shielded C3H1OT1/2 mouse cells. The relative advantage of developing new shielding technologies is discussed in terms of a shield performance as related to biological effect and the resulting uncertainty in estimating astronaut risk.

Schimmerling, W.↗

DOE OSTI2022

Total-internal reflection elastic metasurfaces: design and application

An acoustic shield for protecting a vibrational sensitive device includes a first unit cell and a second unit cell. The first unit cell includes a first locally resonant unit. The first locally resonant unit controls a first phase gradient and the first unit cell includes a first surface. The second unit cell includes a second surface proximate to the first surface. The second unit cell includes a second locally resonant unit embedded along the second interface. The second locally resonant unit controls a second phase gradient. The first phase gradient is different from the second phase gradient. The first unit cell and the second unit cell comprise a super cell. The acoustic shield is configured such that a vibrational wave from a first side of the super cell to a second side of the super cell is substantially attenuated.

Walsh, Timothy↗

NASA NTRS1995

Micro-abrasion package capture cell experiment on the trailing edge of LDEF: Impactor chemistry and whipple bumper shield efficiencies

Four of the eight available double layer microparticle capture cells, flown as the experiment A0023 on the trailing (West) face of LDEF, have been extensively studied. An investigation of the chemistry of impactors has been made using SEM/EDX techniques and the effectiveness of the capture cells as bumper shields has also been examined. Studies of these capture cells gave positive EDX results, with 53 percent of impact sites indicating the presence of some chemical residues, the predominant residue identified as being silicon in varying quantities.

Fitzgerald, Howard J.↗

DOE OSTI2019

Vaccination with Glycan-Modified HIV NFL Envelope Trimer-Liposomes Elicits Broadly Neutralizing Antibodies to Multiple Sites of Vulnerability

The elicitation of broadly neutralizing antibodies (bNAbs) against the HIV-1 envelope glycoprotein (Env) trimer remains a major vaccine challenge. Most cross-conserved protein determinants are occluded by self-N-glycan shielding, limiting B cell recognition of the underlying polypeptide surface. The exceptions to the contiguous glycan shield include the conserved receptor CD4 binding site (CD4bs) and glycoprotein (gp)41 elements proximal to the furin cleavage site. Accordingly, we performed heterologous trimer-liposome prime:boosting in rabbits to drive B cells specific for cross-conserved sites. To preferentially expose the CD4bs to B cells, we eliminated proximal N-glycans while maintaining the native-like state of the cleavage-independent NFL trimers, followed by gradual N-glycan restoration coupled with heterologous boosting. This approach successfully elicited CD4bs-directed, cross-neutralizing Abs, including one targeting a unique glycan-protein epitope and a bNAb (87% breadth) directed to the gp120:gp41 interface, both resolved by high-resolution cryoelectron microscopy. This study provides proof-of-principle immunogenicity toward eliciting bNAbs by vaccination.

1C2↗

DOE OSTI2022

Radiation Effects on Line Heat Detection Cable AP Hot Cells Fire Detection at Brookhaven National Laboratory

Hot cells are used to safely shield workers from high radiation environments while allowing a process to take place within the cell's shielded enclosure, often with the assistance of remote manipulators. The interior of a cell may not be accessible by personnel for years at a time, either due to the lingering radiation environment or due to the constant use of these specialized pieces of equipment. High radiation levels are known to cause undesirable effects and changes to different materials in varying degrees. Selecting equipment for a radiation environment requires an evaluation of materials used (preferably completed assembles), to ensure all interactions of materials are known and ensure that the equipment will have a high degree of reliability and functionality over the intended life of the facility. Hot cells contain systems to support the primary purpose of the enclosure. Fire detection is one such support system. Safety of hot cell operations often establish limits on the amounts of combustibles with the cells, but the presence of some combustible materials is unavoidable. Fire detection is provided to quickly detect a fire and summon manual intervention before damage is too great. Detection may also be used to initiate fire suppression systems. As a safety system, fire detection needs to remain functional to protect the facility throughout the facility's life. Equally important is that the false alarms from the fire detection are minimized to retain confidence in the alarm system and avoid unnecessary interruptions in the hot cell operations. There are many types of fire detection available with various pros and cons. Not all types of fire detection are suited for hot cell application.

36 MATERIALS SCIENCE↗

NASA NTRS2009

Honeycomb vs. Foam: Evaluating Potential Upgrades to ISS Module Shielding

The presence of honeycomb cells in a dual-wall structure is advantageous for mechanical performance and low weight in spacecraft primary structures but detrimental for shielding against impact of micrometeoroid and orbital debris particles (MMOD). The presence of honeycomb cell walls acts to restrict the expansion of projectile and bumper fragments, resulting in the impact of a more concentrated (and thus lethal) fragment cloud upon the shield rear wall. The Multipurpose Laboratory Module (MLM) is a Russian research module scheduled for launch and ISS assembly in 2011 (currently under review). Baseline shielding of the MLM is expected to be predominantly similar to that of the existing Functional Energy Block (FGB), utilizing a baseline triple wall configuration with honeycomb sandwich panels for the dual bumpers and a thick monolithic aluminum pressure wall. The MLM module is to be docked to the nadir port of the Zvezda service module and, as such, is subject to higher debris flux than the FGB module (which is aligned along the ISS flight vector). Without upgrades to inherited shielding, the MLM penetration risk is expected to be significantly higher than that of the FGB module. Open-cell foam represents a promising alternative to honeycomb as a sandwich panel core material in spacecraft primary structures as it provides comparable mechanical performance with a minimal increase in weight while avoiding structural features (i.e. channeling cells) detrimental to MMOD shielding performance. In this study, the effect of replacing honeycomb sandwich panel structures with metallic open-cell foam structures on MMOD shielding performance is assessed for an MLM-representative configuration. A number of hypervelocity impact tests have been performed on both the baseline honeycomb configuration and upgraded foam configuration, and differences in target damage, failure limits, and derived ballistic limit equations are discussed.

Ryan, Shannon J.↗

NASA NTRS1993

A proposed performance index for galactic cosmic ray shielding materials

In past studies, the reductions in absorbed dose and dose equivalent due to choice of material composition have been used to indicate shield effectiveness against exposure to galactic cosmic rays. However, these quantities are highly inaccurate in assessing shield effectiveness for protection against the biological effects of long-term exposure to the galactic heavy ions. A new quantity for shield performance is defined that correlates well with cell killing and cell transformation behind various shield thicknesses and materials. In addition, a relative performance index is identified that is inversely related to biological injury for different materials at a fixed shield mass and is directly related to the ratio of the fourth- and the second-order linear energy transfer (LET) moments.

Wilson, John W.↗