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At least 1,081 records · Page 60

Measuring the Electrochemical Corrosion of 233U-doped UO2 in a Microfluidic Device

We have developed a microfluidic, ‘particle-attached microfluidic electrochemical’ device, or PAMEC, that uses microgram quantities of radioactive materials, such as uranium dioxide (UO2), rather than bulk specimens to both observe electrochemical changes and measure spectroscopic properties. The PAMEC device reduces the need for running experiments in a shielded facility and allows for in-operando, real-time investigations of electrochemical properties and morphological changes of micrograms of particles. This novel design offers a promising platform to investigate spent nuclear fuel (SNF) and other nuclear materials under various controlled condition, and to provide insights to nuclear waste management, and fuel performance

Electrochemistry↗

AniMACCS

AniMACCS is an animation software used in conjunction with MELCOR Accident Consequence Code System (MACCS), which is responsible for estimating the offsite consequences of potential severe accidents at nuclear power plants (NPPs) and of atmospheric releases of radioactive aerosols and gases from other nuclear facilities. MACCS is used to perform probabilistic health and economic consequence assessment of hypothetical releases of radioactive material. AniMACCS utilizes the MACCS output files to generate visual and geographical depictions of the accident consequences. SAND2020-12229 M Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Gallagher, LInda↗

Monitoring the Possible Effects of Corroding Fuel Cladding in Nuclear Ponds: a Modified ROV for Storage Ponds - 20144

Nuclear ponds are used worldwide to store radioactive nuclear material, often for extended periods of time. The pond water conditions need to be closely monitored so that mitigation strategies can be put in place should any leakage of radioactive material occur. This paper describes the selection, development and on-site deployment of a bespoke system whose design was based on of-the-shelf components. The system is able to identify, locate and differentiate the leakage of radioactive material stored in nuclear ponds from the background activity of the water in the pond. The selection of an appropriate detector and monitoring geometry was supported by MCNP modelling which allowed a high degree of confidence in the proposed design. The development of the system allowed a real-time indication of the canister integrity, without incurring the increased operator doses from manual sampling operations that were previously used on site. The benefits of the developed system include the fact that the system is lightweight, easily deployable, retrievable, decontaminable and results in negligible waste products. Moreover, it is able to analyse the samples in-situ, in this way reducing the time needed to manually collect and send the samples to a laboratory for lengthy analysis. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Measurement Quality Objective Considerations for Residual Alpha Surface Radioactivity Measurements at Remediation Sites - 16522

Surveys for residual alpha surface radioactivity on materials, equipment, and other non-porous surfaces are most-commonly performed using the traditional 'best available' equipment. The best available equipment for measuring alpha surface radioactivity includes portable gas-flow proportional or scintillation detectors with active surface areas typically ranging from 50 to 800 square centimeters (cm{sup 2}). The measurement equipment is offered by numerous service providers and instrument vendors applying basic detection principles that date back to the early-Atomic Age. The detector face is held as close to the surface as possible and scanned at a typical rate of 2 to 5 centimeters per second (cm/s). Any audible or visual indication of elevated alpha activity would result in a more careful assessment of the possible 'hot spot'. Modern surface contamination surveys continue to employ these best available technologies while endeavoring to achieve ever more restrictive measurement quality objectives and screening or release criteria. This paper considers the possibly unforeseen consequences to sensitivity and precision as scanning speeds are reduced to meet constraining measurement quality objectives. Sensitivity calculations are conducted to demonstrate how application of real-world efficiencies and the most common survey approaches are inadequate to meet sensitivity objectives based on American National Standard N13.12-2013, Surface and Volume Radioactivity Standards for Clearance screening criteria. Alternate data collection and assessment methodologies are offered to enhance the defensibility of collected data with stakeholders. Limitations of available or applied alpha survey technologies should be considered when establishing survey programs at project sites where alpha-emitting radionuclides are expected to contribute to residual surface radioactivity. These include but are not limited to nuclear fuel-cycle sites, military/weapons/energy research and production facilities, and 19.-20. Century-era commercial/ industrial/research/medical facilities where radioactive materials were handled. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Non-destructive Material Characterization of Radioactive Waste Packages with QUANTOM{sup R} - 20130

During the last decades, the nuclear and non-nuclear industry has produced a considerable amount of low and intermediate level radioactive wastes. In many countries, it is foreseen to dispose of these waste packages safely in a final repository under strict waste acceptance requirements (e.g. the radiological and material characterization) defined by national licensing and supervisory authorities. The material characterization of waste packages can be performed on the basis of existing documentation or, if the documentation is insufficient, on further destructive or non-destructive analysis. Non-destructive methods are to be preferred to minimize radiation exposures of operating personnel as well as costs. We offer here an innovative non-destructive technology called QUANTOM{sup R} (Quantitative Analysis of Toxic and nontoxic Materials) based on prompt and delayed gamma neutron activation analysis (P and DGNAA). This technology is able to identify, quantify and thus verify the amount of hazardous and non-hazardous substances in 200-l radioactive drums, which is required for a final disposal characterization. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Radioactivities of Long Duration Exposure Facility (LDEF) materials: Baggage and bonanzas

Radioactivities in materials onboard the returned Long Duration Exposure Facility (LDEF) satellite were studied by a variety of techniques. Among the most powerful is low background Ge semiconductor detector gamma ray spectrometry. The observed radioactivities are of two origins: those radionuclides produced by nuclear reactions with the radiation field in orbit and radionuclides present initially as contaminants in materials used for construction of the spacecraft and experimental assemblies. In the first category are experiment related monitor foils and tomato seeds, and such spacecraft materials as Al, stainless steel, and Ti. In the second category are Al, Be, Ti, Va, and some special glasses. Consider that measured peak-area count rates from both categories range from a high value of about 1 count per minute down to less than 0.001 count per minute. Successful measurement of count rates toward the low end of this range can be achieved only through low background techniques, such as used to obtain the results presented here.

Smith, Alan R.↗

Radioactivities of Long Duration Exposure Facility (LDEF) materials: Baggage and bonanzas

Radioactivities in materials onboard the returned Long Duration Exposure Facility (LDEF) satellite were studied by a variety of techniques. Among the most powerful is low-background Ge-semiconductor detector gamma-ray spectrometry, illustrated here by results obtained at the Lawrence Berkeley Laboratory's (LBL) Low Background Facilities. The observed radioactivities are of two origins: those radionuclides produced by nuclear reactions with the radiation field in orbit, and radionuclides present initially as 'contaminants' in materials used for construction of the spacecraft and experimental assemblies. In the first category are experiment-related monitor foils and tomato seeds, and such spacecraft materials as aluminum, stainless steel, and titanium. In the second category are aluminum, beryllium, titanium, vanadium, and some special glasses.

Smith, Alan R.↗

Induced radioactivity of LDEF materials and structural components

We present an overview of the Long Duration Exposure Facility (LDEF) induced activation measurements. The LDEF, which was gravity-gradient stabilized, was exposed to the low Earth orbit (LEO) radiation environment over a 5.8 year period. Retrieved activation samples and structural components from the spacecraft were analyzed with low and ultra-low background HPGe gamma spectrometry at several national facilities. This allowed a very sensitive measurement of long-lived radionuclides produced by proton- and neutron-induced reactions in the time-dependent, non-isotropic LEO environment. A summary of major findings from this study is given that consists of directionally dependent activation, depth profiles, thermal neutron activation, and surface beryllium-7 deposition from the upper atmosphere. We also describe a database of these measurements that has been prepared for use in testing radiation environmental models and spacecraft design.

NASA Discipline Radiation Health↗

ORNL Package Testing Program Overview

When transporting radioactive or hazardous materials, safety and security are top priorities. Packaging and transportation regulations require reliable evidence that containers have passed rigorous performance tests to ensure that the public and the environment are protected from the hazardous nature of the cargo. Because of its long history in energy and security research, Oak Ridge National Laboratory (ORNL) has needed to ship hazardous packages for the past 65 years. Since the 1940s, ORNL has made significant contributions to transportation regulations and has been at the forefront of regulatory testing development. Today, ORNL is a leader in standards development and testing of designs of radioactive material packages. ORNL plays a critical role in ensuring the safe transportation of radioactive materials across the United States by executing rigorous testing campaigns of packages that contain radioactive materials. Early testing activities focused on supporting the development of transportation regulations established by both the International Atomic Energy Agency (IAEA) and the United States. Currently, all package testing activities are performed under the Package Testing Program (PTP) at the Package Evaluation Facility (PEF) located at the National Transportation Research Center (NTRC), which is about 10 miles from the main ORNL campus. The PTP develops and evaluates testing solutions, ensuring that they are safe efficient, and in compliance with regulatory requirements. The vision for the PTP is to be a world-class leader in the evaluation and testing of radioactive and hazardous material packages. The key elements necessary to fulfill this mission are an experienced and professional staff; state-of-the-art facilities, equipment, and instrumentation; and completion of challenging programs and projects important to package transportation. Collaborations with other internal and external organizations play a significant role in building stronger teams and achieving this vision. By adhering to and advancing regulatory standards, ORNL’s PTP supports development of safe and compliant packaging, safeguarding the transportation process from potential risks associated with radioactive material logistics.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Trace radioactive impurities in final construction materials for EXO-200

Here, we report results from a systematic measurement campaign conducted to identify low radioactivity materials for the construction of the EXO-200 double beta decay experiment. Partial results from this campaign have already been reported in a 2008 paper by the EXO collaboration. Here we release the remaining data, collected since 2007, to the public. The data reported were obtained using a variety of analytic techniques. The measurement sensitivities are among the best in the field. We concluded the construction of the EXO-200 detector and Phase-I data was taken from 2011 to 2014. The detector’s extremely low background implicitly verifies the measurements and the analysis assumptions made during construction and reported in this paper.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Solidification of radioactive waste resins using cement mixed with organic material

Solidification of radioactive waste resins using cement mixed with organic material i.e. biochar is described in this paper. Different percentage of biochar (0%, 5%, 8%, 11%, 14% and 18%) was investigated in this study. The characteristics such as compressive strength and leaching behavior were examined in order to evaluate the performance of solidified radioactive waste resins. The results showed that the amount of biochar affect the compressive strength of the solidified resins. Based on the data obtained for the leaching experiments performed, only one formulation showed the leached of Cs-134 from the solidified radioactive waste resins.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Leakage Rate Testing Considerations and Implementation of ANSI N 14.5-2014 Standard within EnergySolutions Type (B) cask fleet - 18629

In March 2016, Nuclear Regulatory Commission (NRC) staff issued Information Notice 2016-04: 'ANSI N14.5-2014 Revision and leakage rate testing considerations'. American National Standards Institute (ANSI) N14.5, 'American National Standard for Radioactive Materials-Leakage Tests on Packages for Shipment', applies to leakage rate testing of Low Level Radioactive Waste (LLRW) Type B packages operated under 10CFR71. In their information notice NRC is encouraging Type B cask license holders and licensees (cask users) to adapt a new version of ANSI N 14.5 standard. Typically, leakage rate testing for Type B packages (or casks) is performed at different stages of cask development (design and fabrication leak tests) and operations (periodic/maintenance and pre-shipment leak tests) with the purpose to reasonably assure that the packaging will contain radioactive material under both normal and hypothetical accident conditions of transport described in 10CFR71. The standard was updated to provide a modern, robust and standardized approach for performance of leak rate testing on Type B casks by the industry stakeholders. Although implementation of new version of the leak testing standard may not be problematic for a modern Type B package designs, it may be extremely challenging to apply its principles to the existing legacy Type B casks which were designed/fabricated more then 20-30 years ago based on older requirements. Majority of such casks are not 'leak test' friendly. Some of legacy Type B packages may not readily available to meet newer ANSI N 14.5 standard requirements and will require implementation of alternative compensatory measures in lieu of the standard's requirements. In addition, the new standard mandates implementation of additional requirements for leak rate testing performance and personnel qualifications during routine maintenance of Type B casks by owner and during operations of casks by users. The focus of the paper will be to discuss ANSI N 14.5-2014 requirements and provide specific examples on how these requirements will impact the current leak rate test practices. This will be illustrated based on several Type B cask models operated within EnergySolutions fleet (both newer and legacy cask designs). Finally, the paper will cover considerations of the cask closure design features that have to be considered by Type B cask designers in order to ensure robustness of leak testing during design, fabrication and, most importantly, operation of a package. This information shall benefit both owners and users of Type B casks with respect to improvement of the cask designs and Type B cask operational experience. (author)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Smart Drum Technology for Radioactive and Other Hazardous Materials - 18273

Smart drum technology is the result of a coupling between a robust drum-type package containing radioactive and other hazardous materials and the ARG-US radio frequency identification (RFID) system that enables 'unattended' remote monitoring of the State of Health of the package and contents - in real time, 24/7, with automatic alert/alarm capabilities. Recent educational demos of the system are highlighted. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Low sintering temperature glass waste forms for sequestering radioactive iodine

Materials and methods of making low-sintering-temperature glass waste forms that sequester radioactive iodine in a strong and durable structure. First, the iodine is captured by an adsorbant, which forms an iodine-loaded material, e.g., AgI, AgI-zeolite, AgI-mordenite, Ag-silica aerogel, ZnI.sub.2, CuI, or Bi.sub.5O.sub.7I. Next, particles of the iodine-loaded material are mixed with powdered frits of low-sintering-temperature glasses (comprising various oxides of Si, B, Bi, Pb, and Zn), and then sintered at a relatively low temperature, ranging from 425.degree. C. to 550.degree. C. The sintering converts the mixed powders into a solid block of a glassy waste form, having low iodine leaching rates. The vitrified glassy waste form can contain as much as 60 wt % AgI. A preferred glass, having a sintering temperature of 500.degree. C. (below the silver iodide sublimation temperature of 500.degree. C.) was identified that contains oxides of boron, bismuth, and zinc, while containing essentially no lead or silicon.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗

Radioactivity in returned lunar materials

The H-3, Ar-37, and Ar-39 radioactivities were measured at several depths in the large documented lunar rocks 14321 and 15555. The comparison of the Ar-37 activities from similar locations in rocks 12002, 14321, and 15555 gives direct measures of the amount of Ar-37 produced by the 2 November 1969 and 24 January 1971 solar flares. The tritium contents in the documented rocks decreased with increasing depths. The solar flare intensity averaged over 30 years obtained from the tritium depth dependence was approximately the same as the flare intensity averaged over 1000 years obtained from the Ar-37 measurements. Radioactivities in two Apollo 15 soil samples, H-3 in several Surveyor 3 samples, and tritium and radon weepage were also measured.

Source record↗

Radioactivity Calculator for Research and Test Reactor Neutron-Activated Materials

The Idaho National Laboratory (INL) Nuclear Science User Facility (NSUF) supports nuclear energy-relevant research into the effects of radiation on nuclear fuels and structural materials. The NSUF provides access, at no cost to the researcher, to the Advanced Test Reactor (ATR), the High-Flux Isotope Reactor (HFIR), and other university and national laboratory research and test reactors for radiation effects experiments. Post-irradiation examination of materials poses some difficulties when studying neutron-irradiated materials due to the radioactivity levels of the materials. Inside a test reactor, under high neutron flux, stable materials can activate (capture a neutron) and become unstable or radioactive. These newly created radioactive materials decay, based on their respective half-lives, and emit energetic radiation. Nuclides with short half-lives are able to decay to sufficiently low radiation levels prior to the sample being removed from the reactor. However, nuclides with longer half-lives present a challenge since they must be handled with extreme caution and stored until their radioactivity levels decrease. If immediate examination is required, the examination may take place in a hot cell, which can dramatically increase the cost of the project. The NSUF has access to a variety of hot cells and characterization capabilities at national laboratories, universities, and industrial sites across the United States. In order to estimate the post-irradiation radioactivity levels of materials early in the experiment cycle, we created a radioactivity calculator, hosted on the NSUF web site (nsuf.inl.gov), which will consider three stages of neutron activations and decays for sample materials.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Synthesis and characterization of uranyl chromate sheet compounds containing edge-sharing dimers of uranyl pentagonal bipyramids

Eight uranyl chromates have been crystallized from aqueous solution and characterized: Mg(H{sub 2}O){sub 6}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 2}(OH){sub 2}](H{sub 2}O){sub 3} (1), (NH{sub 4}){sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 2}(OH){sub 2}](H{sub 2}O){sub 3}, Rb{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 2}(OH){sub 2}](H{sub 2}O){sub 3} (3), Cs[(UO{sub 2})(CrO{sub 4})(OH)]H{sub 2}O (4), Rb[(UO{sub 2})(CrO{sub 4})(OH)]H{sub 2}O (5) Co(H{sub 2}O){sub 4}(Co(H{sub 2}O){sub 6}){sub 2}[(UO{sub 2}){sub 4}(CrO{sub 4}){sub 6}(OH){sub 2}](H{sub 2}O){sub 4} (6), Li{sub 2}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}](H{sub 2}O){sub 7} (7), and Zn(H{sub 2}O){sub 6}[(UO{sub 2}){sub 2}(CrO{sub 4}){sub 3}](H{sub 2}O){sub 3} (8). The structural units of 1 through 8 each consist of a sheet of uranyl pentagonal bipyramids and (Cr(VI)O{sub 4}){sup 2-} tetrahedra. In each case two uranyl pentagonal bipyramids share an equatorial edge, giving a dimer that is linked into the sheet through vertex sharing with (Cr(VI)O{sub 4}){sup 2-} tetrahedra. The sheets are based upon three distinct sheet anion topologies, and the sheets based on a given anion topology can differ in the orientations of the non-bridging O atoms of (CrO{sub 4}){sup 2-} tetrahedra. The interlayers of these compounds contain either monovalent or divalent cations, as well as H{sub 2}O groups that are either bonded to the interlayer cation or are held in place by H bonding only. We explore the relationships between sheet topologies and interlayer configuration in these compounds. - Graphical abstract: Eight uranyl chromate compounds containing sheet structural units built from uranyl pentagonal bipyramids and (CrO{sub 4}){sup 2-} tetrahedra are reported. Relationships between sheet topologies and interstitial constituents is examined. Highlights: Black-Right-Pointing-Pointer Eight uranyl Cr(VI) compounds with sheet structural units are reported. Black-Right-Pointing-Pointer Relationships between the topology of the uranyl chromate sheets and interlayers are examined. Black-Right-Pointing-Pointer Uranyl and chromate polyhedra form a topologically novel sheet.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗