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NASA NTRSDate not supplied

Overview of SatCORPS Satellite-Derived Cloud and Radiation Retrieval Coverage of ARM Domains

The ARM Climate Research Facility program maintains a number of climatically representative sites, which provide long-term cloud- and climate-monitoring records via ground-based instrumentation. These measurements provide a valuable data record over a localized region, but can be greatly enhanced by use of satellite monitoring. Satellite analyses over larger domains can provide parameters helpful for monitoring climate and evaluating models. The NASA/Langley Cloud group routinely derives such cloud and radiative parameters, from various geostationary and polar-orbiting satellite coverage over ARM sites; the group provides near-realtime analyses covering the 3 ARM fixed sites, as well as the GO-Amazon AMF site. This is accomplished by employing a suite of algorithms including VISST (Visible Infrared Solar Split-Window Technique), SIST (Solar Infrared Split-Window Technique), and SINT (Solar-infrared Infrared Near-Infrared Technique), now collectively called SatCORPS (Satellite Cloud Observations and Radiative Property retrieval System). An overview and catalog of SatCORPS-derived datasets processed for ASR, and available from both the ARM archive and the NASA/Langley Cloud group website, is provided. Specific improvements included in recently added datasets such as GO-Amazon and Azores are highlighted, including an improved cloud-detection mask, as well as improvements in derived Top-of-Atmosphere (TOA) SW albedoes and LW fluxes. New narrowband-to-broadband (NB-BB) fits and corrections for improved TOA fluxes are illustrated, including MTSAT-1/CERES Aqua NB-BB fits for the TWPICE field campaign, as well as new fits covering the Azores region which incorporate GERB TOA fluxes (Geostationery Earth Radiation Budget). Finally, validation of the reprocessed SatCORPS datasets is shown.

M M Khader↗
DOE OSTI2016

Cosmic Ray Muon Radiography of Spent Fuel in Dry Storage Casks

In the absence of a permanent repository or reprocessing facilities, highly radioactive spent nuclear fuel bundles are typically placed in long-term storage in above ground casks. These dry storage casks are heavily shielded to prevent the escape of radiation from the contents to the environment. Casks under international safeguards are monitored to detect diversion of spent fuel. The heavy shielding of the cask walls also precludes inspection of cask contents with typical radiographic probes. When international safeguards inspectors need to verify cask contents (which may be necessary to recover from a loss of continuity of knowledge), the casks must be moved back into a cooling pool to be safely opened and visually inspected. This time-consuming procedure is invasive and potentially dangerous. A non-destructive radiographic method to verify a cask's contents in situ would therefore be a useful safeguards tool. Highly energetic cosmic ray muons are an alternative tomographic probe. Since muons are colorless leptons, they do not participate in strong interactions with nucleons, and their large mass suppresses radiative energy loss while passing through materials. These properties allow muons to penetrate dense shielding that defeats more typical probes like photons and neutrons. Measurements of the scattering of muons that pass through objects provide information on the object's internal structure. This summary describes the first measurements using cosmic ray muons to inspect the contents of a partially loaded dry storage cask. We show that partial defects in the cask loading can be identified with this technique. This data shows that cosmic ray muons are an effective radiographic probe of dry storage casks. This technique may be useful for international safeguards inspectors wishing to verify a cask's contents without opening it. The analysis techniques described here allow the column of missing fuel bundles to be determined, but not the row. Recording data from several positions around the cask would allow ambiguities in x-y position to be resolved. Alternatively, a detector could be designed such that it surrounds the cask and provides a full image of the casks interior. Improved measurements and the design of optimized cask imaging instruments are being explored. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

FCRD Advanced Reactor (Transmutation) Fuels Handbook

Transmutation of minor actinides such as Np, Am, and Cm in spent nuclear fuel is of international interest because of its potential for reducing the long-term health and safety hazards caused by the radioactivity of the spent fuel. One important approach to transmutation (currently being pursued by the DOE Fuel Cycle Research & Development Advanced Fuels Campaign) involves incorporating the minor actinides into U-Pu-Zr alloys, which can be used as fuel in fast reactors. U-Pu-Zr alloys are well suited for electrolytic refining, which leads to incorporation rare-earth fission products such as La, Ce, Pr, and Nd. It is, therefore, important to understand not only the properties of U-Pu-Zr alloys but also those of U-Pu-Zr alloys with concentrations of minor actinides (Np, Am) and rare-earth elements (La, Ce, Pr, and Nd) similar to those in reprocessed fuel. In addition to requiring extensive safety precautions, alloys containing U, Pu, and minor actinides (Np and Am) are difficult to study for numerous reasons, including their complex phase transformations, characteristically sluggish phasetransformation kinetics, tendency to produce experimental results that vary depending on the histories of individual samples, rapid oxidation, and sensitivity to contaminants such as oxygen in concentrations below a hundred parts per million. Although less toxic, rare-earth elements such as La, Ce, Pr, and Nd are also difficult to study for similar reasons. Many of the experimental measurements were made before 1980, and the level of documentation for experimental methods and results varies widely. It is, therefore, not surprising that little is known with certainty about U-Pu-Zr alloys, particularly those that also contain minor actinides and rare-earth elements. General acceptance of results commonly indicates that there is only a single measurement for a particular property. This handbook summarizes currently available information about U, Pu, Zr, Np, Am, La, Ce, Pr, and Nd and alloys of two or three of these elements. It contains information about phase diagrams and related information (including phases and phase transformations); heat capacity, entropy, and enthalpy; thermal expansion; and thermal conductivity and diffusivity. In addition to presenting information about materials properties, the handbook attempts to provide information about how well the property is known and how much variation exists between measurements. Although it includes some results from models, its primary focus is experimental data. The Handbook is organized in two sections: one with information about the U-Pu-Zr ternary and one with information about other elements and binary and vi ternary alloys in the U-Np-Pu-Am-La-Ce-Pr-Nd-Zr system. Within each section, information about elements is presented first, followed by information about binary alloys, then information about ternary alloys. The order in which the elements in each alloy are mentioned follows the order in the first sentence of this paragraph. Much of the information on the U-Pu-Zr system repeats information from the FCRD Transmutation Fuels Handbook 2015. Most of the other data has been published elsewhere (although scattered throughout numerous references, some quite obscure); however, some data from Idaho National Laboratory is presented here for the first time. As the FCRD programmatic mission evolves, future editions of this handbook will begin to include other advanced reactor fuel designs and compositions. Hence, the title of the handbook will transition to the Advanced Reactor Fuels Handbook.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

West Valley Demonstration Project (WVDP) (Annual Site Environmental Report (ASER), Calendar Year 2022)

The report, prepared for the U.S. Department of Energy West Valley Demonstration Project office (DOE-WVDP), summarizes the environmental protection program at the WVDP for calendar year (CY) 2022. Monitoring and surveillance of the facilities used by the DOE are conducted to verify protection of public health and safety and the environment. The report is a key component of DOE’s effort to keep the public informed of environmental conditions at the WVDP. The quality assurance protocols applied to the environmental monitoring program ensure the validity and accuracy of the monitoring data. In addition to demonstrating compliance with environmental laws, regulations, and directives, evaluation of data collected in 2022 continued to indicate that WVDP activities pose no threat to public health or safety, or to the environment.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

West Valley Demonstration Project (WVDP) Annual Site Environmental Report (ASER) for Calendar Year 2023

The report, prepared for the U.S. Department of Energy West Valley Demonstration Project office (DOE-WVDP), summarizes the environmental protection program at the WVDP for calendar year (CY) 2023. Monitoring and surveillance of the facilities used by the DOE are conducted to verify protection of public health and safety and the environment. The report is a key component of DOE’s effort to keep the public informed of environmental conditions at the WVDP. The quality assurance protocols applied to the environmental monitoring program ensure the validity and accuracy of the monitoring data. In addition to demonstrating compliance with environmental laws, regulations, and directives, evaluation of data collected in 2023 continued to indicate that WVDP activities pose no threat to public health or safety, or to the environment.

Record of Decision↗
NASA NTRS2003

Global Properties of Local Star Forming Galaxies (ADP 2000)

We performed an archival study of the Hopkins Ultraviolet Telescope (HUT) Astro-2 database. Nineteen spectra of star-forming regions and starburst galaxies were retrieved, reprocessed, and analyzed. The spectra cover the wavelength region 912- 1800 A, providing access to the domain of peak luminosity from a young stellar population. We created an atlas of galaxy spectra documenting the continuum and line properties with an emphasis on the relatively unexplored spectral region below 1200 A. The dust obscuration law was derived from a comparison of the HUT spectra with synthetic population models. The law is similar to the commonly adopted starburst reddening curve at longer wavelengths and approaches the Milky Way law near the Lyman break. A simple power-law parameterization is given, which allows users to express the reddening law in terms of the stellar or nebular color excess at ultraviolet or optical wavelengths. We studied the effect of time-dependent dust obscuration on synthetic ultraviolet line profiles of a young stellar population. If the youngest and most massive stars are more obscured than the older, less massive stars, the C IV 1550 and other stellar wind lines are significantly diluted with respect to a simple foreground screen model for the dust. We propose to use stellar wind lines as a probe of the dust-obscuration model instead of the previously employed nebular emission lines. Since purely stellar diagnostics are utilized, uncertain assumptions on the nebular properties are unnecessary. Photoionization models demonstrate that the C IV 1550 emission is typically dominated by stellar winds and nebular contamination is negligible. A first comparison with the galaxy sample observed with the Hopkins Ultraviolet Telescope favors a dust geometry affecting ionizing and nonionizing stars equally. We point out the need for higher quality data for a more rigorous comparison. The Hubble Space Telescope is capable of obtaining such data in the future.

Leitherer, Claus↗
DOE OSTI2019

Iodine Retention of Long-chain Organic Iodides on Silver-based Sorbents under DOG and VOG Conditions

The aqueous reprocessing of used nuclear fuel releases four key volatile radionuclides ( 3 H, 14 C, 85 Kr, and 129 I) from the used fuel into the off-gas streams of a reprocessing facility. Some semi-volatile radionuclides such as 106 Ru may also be released into the gas streams. Compliance with US regulations may require removal of these radionuclides from the off-gas streams before their discharge to the environment (Jubin et al. 2017). Iodine is released during multiple unit operations within a plant and can be found in gas streams such as the shear off-gas, dissolver off-gas, vessel off-gas (VOG), and waste solidification off-gas. To achieve DFs >1,000, treatment of the plant off-gas streams must include, at minimum, removal of both the dissolver off-gas and VOG. A 2015 analysis showing that the speciation of iodine in the VOG is primarily composed of organic alkyl iodides and that abatement technology for organic iodides is not well developed has produced increased interest in removing iodine from VOG. The lack of knowledge surrounding iodine removal from the VOG prompted the Office of Nuclear Energy within the US Department of Energy to initiate experimental efforts targeted at understanding organic iodide removal from prototypic VOG streams. In 2018 a joint test plan was developed and issued by Oak Ridge National Laboratory and Idaho National Laboratory. This test plan is intended to guide a multiyear experimental effort that will provide substantial amounts of information about the removal of organic iodides from VOG streams. This document reports on the progress of Idaho National Laboratory and Oak Ridge National Laboratory in the execution of the joint test plan as of the end of fiscal year 2019. Silver-based sorbents are the primary removal technology being characterized, and this report includes data on iodine adsorption by reduced silver-exchanged mordenite (also called silver-exchanged zeolite [AgZ]) (as a baseline iodine sorbent) and silver-functionalized silica aerogel (AgAero or Ag Aerogel) (as an advanced iodine sorbent). Conclusions are preliminary in nature and reflect the ongoing execution of the test plan through close collaboration between the two laboratories.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Re-evaluation of the Gamma Radiolysis Radiation Chemistry of Neptunium

The reprocessing of spent nuclear fuel by solvent extraction techniques starts with dissolving fuel in concentrated nitric acid (HNO{sub 3}). The resulting radioactive liquor is subjected to multiple stages of solvent extraction to partition desired metal ions (e.g. uranium, plutonium, and neptunium) into an organic phase using specialized extractants. Under process conditions the solvent system is continuously exposed to a high intensity radiation field, which induces radiolytic degradation of both the diluent and extractants. This degradation occurs through the formation of radicals, as well as degradation products. Moreover, both radicals and degradation products can undergo redox chemistry with metal ions within the solvent system. This can be particularly problematic for metals such as neptunium which depend on the maintenance of a particular valence state amenable to complexation by extractants such as tributylphosphate in the PUREX (Plutonium Uranium Redox Extraction) process. Neptunium (Np) is well extracted when it is Np(IV) and Np(VI) but almost unextractable when Np(V). A recently study showed that the radiolysis of Np (VI) in acidic (4 M HNO{sub 3}) solution underwent reduction to Np(V). This reduction only occurred after sufficient production of nitrous acid (HNO{sub 2}) which countered the action of radiolytically-produced oxidizing free radicals (nitrate radical, NO{sub 3}{sup .} and hydroxyl radical, {sup .}OH). This radiation-induced chemistry was successfully modeling using a simplified kinetic model, that included a reaction set for water radiolysis, plus published rate constants for the reactions of free radicals with Np(VI) and Np(V). The most sensitive reaction rate constants were identified in this model, and optimization of the five most sensitive was performed to get excellent model agreement with the experimental data. No Np(IV) was observed or predicted by the model under these conditions. The present research re-evaluates this radiation chemistry of neptunium in aerated aqueous solutions of HNO; by using a far more comprehensive FACSIMILE code. We have also extended this modeling to study the radiolytically-induced Np redox chemistry occurring under multiple other nitric acid acidities, to fully characterize the importance of the oxidizing radical and reducing nitrous acid reactions under a range of conditions relevant to large-scale process conditions. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

The Effect of Kr-85 Decay to Rb-85 on Waste Forms - 17105

Krypton-85 (Kr-85) is a volatile radionuclide released during the reprocessing of used nuclear fuel (UNF). Prior to discharge of process off-gas streams to the environment, removal of Kr-85 is required to meet emission regulations. Once removed from the off-gas streams, Kr (containing stable Kr in addition to Kr-85) must be placed in storage until the Kr-85 has decayed to levels such that its potential release would meet regulatory guidelines. The current method of storage is high-pressure metal canisters. Historically, concerns have been expressed that the decay product of Kr-85, Rubidium-85 (Rb-85), could cause corrosion and weakening in the canisters that would ultimately lead to premature failure and release of Kr-85. Alternate methods and materials, such as matrix isolation in a vapor deposited metal and immobilization in zeolites, have been investigated as storage approaches for Kr. However, even these storage methods may become compromised due to the chemical effects of Rb-85 arising from the decay of Kr-85. A review was conducted of the available literature to examine topics relevant to the effects of Rb on the long-term storage of Kr-85, examine the source terms in the context of this concern, and suggest a path forward to resolve outstanding knowledge gaps. In the course of this analysis, several knowledge gaps were identified. Examples include: o The use of solid sorbents to potentially permit more Kr-85-bearing gas to be loaded into canisters, either at the pressures used in the current method or at significantly lower pressures. o A cost-to-benefit analysis is needed to ascertain the practicality of manufacturing waste forms for Kr-85 storage with solid sorbents. o The effects of radiation and chemical transmutation in solid sorbents or matrices for this application are virtually unknown. o Fundamental data are needed on corrosion rates and mechanisms as functions of Rb concentration, storage temperature, etc., for various storage approaches (e.g., as compressed gas or encapsulated in a getter material) and storage container materials. The present analysis focused on the available information regarding storage of Kr-85 in high-pressure containers. It was judged unlikely that such containers would be compromised by corrosion from the Rb decay product, especially if the Kr recovery operations result in a gas composition with very low oxygen content. However, this conclusion should be revisited based on preliminary data gathered from analysis of legacy Kr waste forms. These legacy waste forms are a result of experiments conducted at Idaho National Laboratory over 30 y ago and have been stored for more than three Kr-85 half-lives. Evaluation of these forms indicates significant corrosion, the cause of which has not been conclusively determined. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1997

Near-Surface Phytoplankton Pigment from the Coastal Zone Color Scanner in the Subantarctic Region Southeast of New Zealand

Primarily based on satellite images, the phytoplankton concentration southeast (down- stream) of New Zealand in the High Nitrate - Low Chlorophyll (HNLC) Subantarctic water between the Subtropical Convergence (STC) and the Polar Front (PF) is believed to be higher than in the remainder of the Pacific Sector. Iron enrichment is assumed to be the reason, To study the question, near-surface phytoplankton pigment estimates from the Coastal Zone Color Scanner for up to 7 yr were reprocessed with particular attention to interference by clouds. Monthly mean images were created for the U,S. JGOFS Box along 170 deg W and means for individual dates calculated for 7 large areas between 170 deg E and 160 deg W, 45 deg and 58 deg S, well offshore of New Zealand and principally between and away from the STC and PF. The areal means are about as low as in other HNLC regions (most values between 0.1 and 0.4 or 0.5 mg/ sq m, with very few winter images; median of seasonal means, 0.26 mg/sq m) except at times near the STC, The higher means tend to occur in late summer and autumn, However, contrary to expectations, neither the PF nor the environs of the Subantarctic Front are distinguished by a zone of increased pigment. Also, of 24 spring-summer images of oceanic islands in mostly pigment-poor water, 17 yielded no recognizable elevated pigment; islands were 5 times surrounded by approximately doubled concentrations (ca 100 km in diameter), and 2 cases may have been associated with an extensive bloom. Inspection of offshore images showed concentrations of 1 greater than or equal to(up to 5) mg/sq m in rare patches of 65 to 200 km size on approximately one-tenth of the dates; such patches were not seen in Sub-antarctic waters of the eastern Pacific Sector. A case is made for Australian airborne iron supply being the cause that, presumably, would enhance large-celled phytoplankton. Since, however, the putative iron supply from the seabed around the oceanic islands or the near-by Campbell Plateau normally does not lead to phytoplankton increase, patches of neritic mesozooplankton advected from the shelves might be another mechanism that generates blooms of small-cetled phytoplankton, but there are no data. These alternatives can easily be field-tested from concentration and size composition of the phytoplankton.

Banse, Karl↗
DOE OSTI2026

West Valley Demonstration Project (WVDP) Annual Site Environmental Report (ASER) for Calendar Year 2025

The report, prepared for the U.S. Department of Energy West Valley Demonstration Project office (DOE-WVDP), summarizes the environmental protection program at the WVDP for calendar year (CY) 2025. Monitoring and surveillance of the facilities used by the DOE are conducted to verify protection of public health and safety and the environment. The report is a key component of the DOE’s effort to keep the public informed of environmental conditions at the WVDP. The quality assurance protocols applied to the environmental monitoring program ensure the validity and accuracy of the monitoring data. In addition to demonstrating compliance with environmental laws, regulations, and directives, the evaluation of data collected in 2025 continued to indicate that WVDP activities posed no threat to public health or safety, or to the environment.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2019

Iodine Capture and Mechanical Stability of Modified Silver-Functionalized Silica Aerogel

Silver-functionalized silica aerogel (AgAero) is a material proposed for use in the removal of iodine from the off-gas streams arising from nuclear fuel reprocessing. This material was developed by Pacific Northwest National Laboratory and has been shown to adsorb up to 300 mg of iodine per gram of AgAero. One of the challenges noted for AgAero as an iodine sorbent is its mechanical stability. Its initial particle size is >0.85 mm, but previous testing has shown that extended exposure to heated gas streams results in the degradation of the material such that the sorbent bed is compacted with a substantial amount of fines produced. The observed mechanical degradation prompted an effort to reengineer the silica aerogel to improve the mechanical stability of the material without compromising its iodine capture characteristics. Pacific Northwest National Laboratory has modified the material with the intention of strengthening the aerogel backbone and improving mechanical durability. This reengineered material was transferred to Oak Ridge National Laboratory for extended testing to assess its mechanical durability. Modified AgAero was continuously exposed to a CH 3 I-bearing humid gas stream for 84 days. Testing was performed at 150°C with a superficial gas velocity of 10 m/min., a CH 3 I concentration of 554 ppb, and an inlet dew point of 10°C. The density of the AgAero increased by 16% during testing, and the height of the column was observed to decrease by 11%. The fines produced by the material were comparable to that of previously supplied material. Additionally, iodine loading of a thin bed of modified AgAero was performed at 150°C with a superficial gas velocity of 10 m/min. and a CH 3 I concentration of 50 ppm (balance dry air) with a total test duration of 1 week. The CH 3 I capture capacity of the reengineered material was 225 mg iodine per gram AgAero, as compared to a CH 3 I capacity of 250 mg iodine per gram AgAero for the original material. The primary data collected were visual observations, density measurements before and after testing, and the extent of column compaction during testing. Additionally, the material was tested to ensure that the iodine capacity of the material was not adversely impacted by the alternative methods used in the production of the reengineered material. Based on these criteria, no distinguishable improvements were observed between the material produced in fiscal years 2017 and 2019 and the mechanical stability of the aerogel in prototypic off-gas conditions remains a challenge to large-scale deployment.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1992

The x ray variability of NGC6814: Power spectra

Simulation techniques are used to obtain the X-ray variability power spectrum of unevenly sampled GINGA data from NGC6814. A simple power law is not an adequate description of the power spectrum, with the residuals showing excess power on timescales consistent with the periodicity seen in EXOSAT observations of this object. However the shape of the folded lightcurve is very different, with 3 main peaks, two of which are separated by an extremely sharp dip instead of the single peak and small harmonic structure observed by EXOSAT. Using the dip as a fiducial mark, a second GINGA observation of this source taken one year later is found to be consistent with being completely periodic and phase coherent with this first GINGA observation. Thus the period is consistent with being constant over a period of 6 years, but phase coherence is only maintained on timescales of approximately 1 year. Over 75 percent of the total source variability is due to the periodic component (r.m.s. amplitude of 36 percent). The residual variability can be described as the more usual 'flicker noise' f(exp -1.1) powerlaw. This shows no apparent high frequency break on timescales greater than 300 seconds. Subtle differences in the shape of the folded light curve with energy, and the very large amount of power in the periodic component suggest occultation as its origin, though amplification of variability from an X-ray emitting 'hot spot' at the disk inner radius through gravitational lensing is also possible. The former suffers from the very arbitrary nature of the periodic timescale, while the latter is unattractive as it cannot simply explain the lack of high frequency break in the residual power. That these models probably fail to provide an adequate explanation may be due to the added complexity of anisotropy of the X-ray emission, suggested by the discrepancy between the lack of soft photons implied by the flat spectrum and the copious source of soft photons available from reprocessing in the iron line producing material.

Done, C.↗
DOE OSTI2025

West Valley Demonstration Project (WVDP) Annual Site Environmental Report (ASER) for Calendar Year 2024

The report, prepared for the U.S. Department of Energy West Valley Demonstration Project office (DOE-WVDP), summarizes the environmental protection program at the WVDP for calendar year (CY) 2024. Monitoring and surveillance of the facilities used by the DOE are conducted to verify protection of public health and safety and the environment. The report is a key component of DOE’s effort to keep the public informed of environmental conditions at the WVDP. The quality assurance protocols applied to the environmental monitoring program ensure the validity and accuracy of the monitoring data. In addition to demonstrating compliance with environmental laws, regulations, and directives, evaluation of data collected in 2024 continued to indicate that WVDP activities pose no threat to public health or safety, or to the environment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Predicting cutoff L-shells of solar protons using the GPPSn particle dataset

Solar energetic protons (SEPs) arriving at the Earth trigger severe radiation storms in the near-Earth space, directly impacting space missions operating at various altitudes. Therefore, monitoring SEP events and predicting the penetration depths of solar protons are critical for aerospace sectors. Building on previous efforts, here we demonstrate the feasibility of using proton measurements from the Global Prompt Proton Sensor network (GPPSn), enabled by Los Alamos National Laboratory developed combined X-ray dosimeters aboard GPS satellites, to characterize and predict the penetration of solar protons into the geomagnetic field. The inclined medium-Earth-orbits (MEOs) of the global GPS constellation offer a unique advantage of allowing simultaneous measurements of penetrating solar protons inside both open- and closed-field line regions. Therefore, the L-profiles of ∼10s–100 MeV solar protons and their associated cutoff L-shells can be determined from the GPPSn dataset, using predefined threshold proton flux values rather than traditional flux ratios. After examining a list of SEP event intervals across solar cycles 23, 24 and 25—including the 2024 Mother’s Day superstorm, we showcase how the latest GPPSn proton dataset (release v1.10), reprocessed and calibrated, can not only be used to monitor solar proton distributions inside the dynamic geomagnetic field for individual events, but also to derive a new empirical model linking cutoff L-shells with several key space weather parameters. This newly developed SEPCL-MEO model demonstrates high predictive performance; for example, predictions for > 30 MeV solar protons yield a correlation coefficient of 0.85 and performance efficiency of 0.67 when validated against GPPSn observations. Results from this pilot study underscores the scientific and operational value of the GPPSn dataset, and this dataset—when paired with machine-learning techniques—can play a critical role in observing and predicting the effects of future incoming SEP events, including extreme ones.

58 GEOSCIENCES↗
DOE OSTI2017

Developing a new criticality methodology to support decommissioning of legacy plutonium facilities

To decommission a legacy plutonium finishing facility, a number of gloveboxes need to be disposed of. These gloveboxes have been in place since the 1960's and were operational until the 1980's. A period of initial clean out and decommissioning took place in the 1990's and the first gloveboxes were removed from the line in the early 2000's. Compliance with downstream waste handling facility requirements meant that the gloveboxes needed to be removed using intensive 'hands-on' methods in order to size reduce them to fit into 200 litre (55 gallon) drums. This is the standard approach for handling waste items known as Plutonium Contaminated Material (PCM) on the Sellafield site and was credited in the criticality safety case for the decommissioning of the gloveboxes as it allowed each waste drum to be individually assayed such that the fissile content of the waste could be known. Not only was this approach time-consuming and laborious but as it involved operators working with cutting tools in a highly contaminated area it was challenged as being overly restrictive to operations and potentially hazardous to the workers. In order to decommission the remaining nine gloveboxes in the facility, a new decommissioning approach and associated criticality methodology has been developed. Instead of intensive size reduction and waste drum assay, the gloveboxes will be removed with little or no size reduction and put into storage crates without assay. The criticality assessor will review the operational history of each glovebox, along with the decommissioning records and relevant plant data, to make an evidence-based judgement that the crated glovebox represents no greater a residual criticality risk than would have been realised from the equivalent number of PCM drums that the standard decommissioning approach would have generated. This method identifies, in conjunction with the plant personnel, a number of review points to ensure that before the glovebox is removed any bulk residue material has been recovered and no more than a safe amount of moderating material (fixative) has been added to fix any remaining fissile contamination. Finally, once these review points have been confirmed to be complete - through a stakeholder meeting with criticality safety, plant operators and project managers - the glovebox will be placed in a crate, and this crate will be declared a Low Criticality Risk crate. No formal assay will be required prior to exporting the crate to the downstream waste handling facility and no fissile mass value will be assigned to the contents of the crate. No further intrusive work will be required on the crate and it can be safely stored without any spacing requirements, pending final disposal. (author)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2014

West Valley Demonstration Project Annual Site Environmental Report Calendar Year 2013

West Valley Demonstration Project (WVDP) Annual Site Environmental Report (ASER) for Calendar Year 2013. The report, prepared for the U.S. Department of Energy West Valley Demonstration Project office (DOE-WVDP), summarizes the environmental protection program at the WVDP for calendar year (CY) 2013. Monitoring and surveillance of the facilities used by the DOE are conducted to verify protection of public health and safety and the environment. The report is a key component of DOE’s effort to keep the public informed of environmental conditions at the WVDP. The quality assurance protocols applied to the environmental monitoring program ensure the validity and accuracy of the monitoring data. In addition to demonstrating compliance with environmental laws, regulations, and directives, evaluation of data collected in 2013 continued to indicate that WVDP activities pose no threat to public health or safety, or to the environment.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2015

Stationary Liquid Fuel Fast Reactor

For effective burning of hazardous transuranic (TRU) elements of used nuclear fuel, a transformational advanced reactor concept named SLFFR (Stationary Liquid Fuel Fast Reactor) was proposed based on stationary molten metallic fuel. The fuel enters the reactor vessel in a solid form, and then it is heated to molten temperature in a small melting heater. The fuel is contained within a closed, thick container with penetrating coolant channels, and thus it is not mixed with coolant nor flow through the primary heat transfer circuit. The makeup fuel is semi- continuously added to the system, and thus a very small excess reactivity is required. Gaseous fission products are also removed continuously, and a fraction of the fuel is periodically drawn off from the fuel container to a processing facility where non-gaseous mixed fission products and other impurities are removed and then the cleaned fuel is recycled into the fuel container. A reference core design and a preliminary plant system design of a 1000 MWt TRU- burning SLFFR concept were developed using TRU-Ce-Co fuel, Ta-10W fuel container, and sodium coolant. Conservative design approaches were adopted to stay within the current material performance database. Detailed neutronics and thermal-fluidic analyses were performed to develop a reference core design. Region-dependent 33-group cross sections were generated based on the ENDF/B-VII.0 data using the MC2-3 code. Core and fuel cycle analyses were performed in theta-r-z geometries using the DIF3D and REBUS-3 codes. Reactivity coefficients and kinetics parameters were calculated using the VARI3D perturbation theory code. Thermo-fluidic analyses were performed using the ANSYS FLUENT computational fluid dynamics (CFD) code. Figure 0.1 shows a schematic radial layout of the reference 1000 MWt SLFFR core, and Table 0.1 summarizes the main design parameters of SLFFR-1000 loop plant. The fuel container is a 2.5 cm thick cylinder with an inner radius of 87.5 cm. The fuel container is penetrated by twelve hexagonal control assembly (CA) guide tubes, each of which has 3.0 mm thickness and 69.4 mm flat-to-flat outer distance. The distance between two neighboring CA guide tube is selected to be 26 cm to provide an adequate space for CA driving systems. The fuel container has 18181 penetrating coolant tubes of 6.0 mm inner diameter and 2.0 mm thickness. The coolant tubes are arranged in a triangular lattice with a lattice pitch of 1.21 cm. The fuel, structure, and coolant volume fractions inside the fuel container are 0.386, 0.383, and 0.231, respectively. Separate steel reflectors and B4C shields are used outside of the fuel container. Six gas expansion modules (GEMs) of 5.0 cm thickness are introduced in the radial reflector region. Between the radial reflector and the fuel container is a 2.5 cm sodium gap. The TRU inventory at the beginning of equilibrium cycle (BOEC) is 5081 kg, whereas the TRU inventory at the beginning of life (BOL) was 3541 kg. This is because the equilibrium cycle fuel contains a significantly smaller fissile fraction than the LWR TRU feed. The fuel inventory at BOEC is composed of 34.0 a/o TRU, 41.4 a/o Ce, 23.6 a/o Co, and 1.03 a/o solid fission products. Since uranium-free fuel is used, a theoretical maximum TRU consumption rate of 1.011 kg/day is achieved. The semi-continuous fuel cycle based on the 300-batch, 1- day cycle approximation yields a burnup reactivity loss of 26 pcm/day, and requires a daily reprocessing of 32.5 kg of SLFFR fuel. This yields a daily TRU charge rate of 17.45 kg, including a makeup TRU feed of 1.011 kg recovered from the LWR used fuel. The charged TRU-Ce-Co fuel is composed of 34.4 a/o TRU, 40.6 a/o Ce, and 25.0 a/o Co.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗