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Implementing a Low Activity Waste Direct Feed Capability in the Hanford Waste Treatment Plant - 17277

The original design of the Waste Treatment and Immobilization Plant (WTP) requires that all waste be processed through the Pretreatment (PT) Facility in order to separate the low-activity waste and high-level waste streams. The U.S. Department of Energy (DOE) has developed a sequenced approach to completing the WTP Project, beginning with feeding some liquid waste directly to the Low-Activity Waste (LAW) Facility, bypassing the PT Facility. Sending low-activity waste from the tank farms to the LAW Facility is referred to as direct-feed LAW (DFLAW). Using this approach, low-activity waste will be pretreated in a Low-Activity Waste Pretreatment System (LAWPS) for cesium and solids separation to meet LAW Facility safety basis requirements and produce an acceptable low-activity waste product. The waste feed will then be transferred to the LAW Facility where it will be immobilized in glass, poured into stainless steel containers, and then transported by truck to the Integrated Disposal Facility, a mixed waste burial ground located in the Hanford 200-East Area. The primary driver for the DFLAW approach is to enable commissioning of the LAW Facility for low-activity waste processing prior to the completion and availability of the PT and High-Level Waste (HLW) facilities. As such, the functions intended to be provided to the LAW Facility by the PT Facility and the common functionality with the HLW Facility must be refined and modified to enable DFLAW operations. The DFLAW approach will provide necessary systems and facilities to replace these enabling PT Facility functions until the PT Facility is completed and commissioned. For example, liquid effluents from the LAW Facility, primarily melter offgas condensate, will be processed in a new effluent management facility (EMF) within the WTP footprint rather than sending the effluent back to the PT Facility for processing. During DFLAW operations approximately 3 785 m{sup 3} (1 million gallons) of double-shell tank (DST) waste will be delivered to WTP for treatment each year of operation, and nominally produce 21 metric tons of immobilized low-activity waste glass per day. The resultant freed space in the DSTs will support safe tank farm operation and staging of additional waste for treatment. In December 2016, DOE executed a contract modification and approved an incremental change to the project's performance baseline to complete the WTP facilities needed to allow direct feed of low-activity waste to the LAW Facility. The revised performance baseline supports completion and cold commissioning of the WTP facilities needed for DFLAW operations no later than August 2023. The design of modifications to WTP facilities needed to enable DFLAW operations is more that 60 percent complete. DOE approved the preliminary safety basis for DFLAW modifications to WTP based on the 30 percent design package in early 2016. Early construction work for DFLAW modifications to WTP began in mid-2015. Long-lead procurement actions for some of the more complex equipment needed for LAW Facility effluent treatment were initiated in early 2016. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

PFLOTRAN Development FY2021

The Spent Fuel & Waste Science and Technology (SFWST) Campaign of the U.S. Department of Energy (DOE) Office of Nuclear Energy (NE), Office of Spent Fuel & Waste Disposition (SFWD) is conducting research and development (R&D) on geologic disposal of spent nuclear fuel (SNF) and high-level nuclear waste (HLW). A high priority for SFWST disposal R&D is to develop a disposal system modeling and analysis capability for valuating disposal system performance for nuclear waste in geologic media. This report describes fiscal year (FY) 2021 advances of the PFLOTRAN Development group of the SFWST Campaign. The mission of this group is to develop a geologic disposal system modeling capability for nuclear waste that can be used to probabilistically assess the performance of generic disposal concepts. In FY 2021, development proceeded along three main thrusts: software infrastructure, code performance, and process model advancement. Software infrastructure improvements included implementing an Agile software development framework and making improvements to the QA Test Suite. Code performance improvements included development of advanced linear and nonlinear solvers as well as design of flexible smoothing algorithms for capillary pressure functions. Process modeling advancements included the addition of flexible thermal conductivity function definitions and refinement of multi-continuum reactive transport to support Sandia’s participation in DECOVALEX. This report fulfills the GDSA PFLOTRAN Development Work Package Level 3 Milestone – PFLOTRAN Development, FY2021, M3SF-21SN010304072.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

West Valley Demonstration Project Annual Site Environmental Report (ASER) for Calendar Year 2015

West Valley Demonstration Project (WVDP) Annual Site Environmental Report (ASER) for Calendar Year 2015. 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) 2015. 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 2015 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↗

TRUPACT-III Program Guidance (Rev. 0)

The purpose of this document is to provide the technical requirements for preparation for use, operation, inspection, and maintenance of a Transuranic Package Transporter Model IIl (TRUPACT-IlI) and directly related components. This document complies with the minimum requirements as specified in the TRUPACT-lII Safety Analysis Report for Packaging (SARP) and U.S. Nuclear Regulatory Commission (NRC) Certificate of Compliance (C of C) No. 9305.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Destructive examination of shipping package 9975-02101

Destructive and non-destructive examinations have been performed on the components of shipping package 9975-02101 as part of the comprehensive Model 9975 package surveillance program. This package is one of ten high-wattage packages that were selected for field surveillance in FY15, and was identified to contain several non-conforming conditions. Most of these conditions (mold, stains, drum corrosion, calculated fiberboard dimensions and fiberboard damage) relate to the accumulation of water in the outer and lower portions of the cane fiberboard assembly. In the short term, this causes local but reversible changes in the fiberboard properties. Long-term effects can include the permanent loss of fiberboard properties (thus far observed only in the bottom fiberboard layers) and reduced drum integrity due to corrosion. The observed conditions must be fully evaluated by KAC to ensure the safety function of the package is being maintained. Three of the other nine FY15 high-wattage packages examined in the K-Area Complex showed similar behavior. Corrosion of the overpack drum has been seen primarily in those packages with relatively severe fiberboard degradation. Visual examination of the drums in storage for external corrosion should be considered as a screening tool to identify additional packages with potential fiberboard degradation. Where overpack drum corrosion has been observed, it is typically heaviest adjacent to the stitch welds along the bottom edge. It is possible that changes to the stitch weld design would reduce the degree of corrosion in this area, but would not eliminate it. Several factors can contribute to the concentration of moisture in the fiberboard, including higher than average initial moisture content, higher internal temperature (due to internal heat load and placement with the array of packages), and the creation of additional moisture as the fiberboard begins to degrade.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Milli-Watt Radioisotope Power to Enable Small, Long-Term Robotic “Probe” Space Exploration

Milli-watt Radioisotope Power Systems (RPS) based on Radioisotope Heater Units (RHUs) could be an ideal power source for certain spacecraft that cannot use solar power due to large distances from the sun, or other environmental constraints, and where they enable or significantly enhance the ability of a mission to meet its scientific or operational goals. Various modular, compact RHU-based thermoelectric (TE) generator concepts developed or derived from current NASA Small Business Innovation Research (SBIR) projects satisfying this need have been investigated. These modular, compact and low mass power systems could support small, highly-mobile robotic exploration packages, and could be incorporated into different robotic package concepts, spacecraft or satellites. Current modular RPS design concepts with 40mW, 80mW and 120mW power levels use RHUs and Bi2Te3 TE converters. Skutterudites materials could be used in the future if new higher thermal energy output and higher temperature miniature heat sources were developed, for example, using technologies currently in the General Purpose Heat Source (GPHS) used in higher electric power output RTGs. Small (a.k.a., “mice-like”) robotic packages could effectively utilize these RHU-driven power levels to accommodate crawling, climbing, monitoring, taking measurements, and communicating during long-term planetary missions aimed at gathering environmental and geologic data (i.e., over multiple decades). Waste heat from the cold side of the TE converter could also be directed toward the electronics and / or energy storage (e.g. batteries) to keep them within design temperature ranges. In addition to power generation and electronics / battery heating, the RHU / TE configuration could be designed to survive an external 500°C bake out procedure for critical spacecraft sterilization, environmental certification and planetary protection. Analytical studies have been performed to optimize various design configurations for power, mass, volume and robotic mobility. Specific power (mW/kg) and volumetric specific power (mW/cm3) characteristics of various design configurations will be presented and key conceptual design tradeoffs will be discussed. Hot- and cold-side thermal interfaces required to meet power and mass goals and associated design sensitivities will also be discussed. RHU / TE systems must overcome critical design challenges to survive high-g loadings in some robotic applications and we will examine the mass impacts required to satisfy various dynamic loading environments up to 10,000 g’s. Power can be generated for a minimum of 30 years or more using plutonium-238 dioxide heat sources (given that Pu-238 has an 87.7 year half-life) with some reduction in power as the heat source naturally degrades.

Bahrami, Poyan↗

When Spreadsheets Become Software - Quality Control Challenges and Approaches - 13360

As part of a preliminary waste acceptance criteria (PWAC) development, several commercial models were employed, including the Hydrologic Evaluation of Landfill Performance model (HELP) [1], the Disposal Unit Source Term - Multiple Species model (DUSTMS) [2], and the Analytical Transient One, Two, and Three-Dimensional model (AT123D) [3]. The results of these models were post-processed in MS Excel spreadsheets to convert the model results to alternate units, compare the groundwater concentrations to the groundwater concentration thresholds, and then to adjust the waste contaminant masses (based on average concentration over the waste volume) as needed in an attempt to achieve groundwater concentrations at the limiting point of assessment that would meet the compliance concentrations while maximizing the potential use of the landfill (i.e., maximizing the volume of projected waste being generated that could be placed in the landfill). During the course of the PWAC calculation development, one of the Microsoft (MS) Excel spreadsheets used to post-process the results of the commercial model packages grew to include more than 575,000 formulas across 18 worksheets. This spreadsheet was used to assess six base scenarios as well as nine uncertainty/sensitivity scenarios. The complexity of the spreadsheet resulted in the need for a rigorous quality control (QC) procedure to verify data entry and confirm the accuracy of formulas. (authors)

54 ENVIRONMENTAL SCIENCES↗

Degradation of ILW Drums Due to Internal Metallic Corrosion - 18036

Within the British nuclear inventory, metallic Intermediate Level Waste (ILW) is encapsulated in grout and stored in stainless steel drums. Based on recent inspections held in the relevant storage facilities (Sellafield, Cumbria), a proportion of these drums have exhibited considerable distortion, raising concerns about the long-term safety of the packages. Distortion may be caused by the generation of voluminous and potentially flammable substances resulting from metallic corrosion occurring within the drums' core. Potential oxygen influx in the event of steel fracture and consequently drum's failure could potentially cause release or even ignition of the encapsulated radioactive material. The mechanical degradation of the encapsulants (stainless steel and grout) induced from the progressive corrosion of the encapsulated metallic components (and the associated volume expansion) was investigated using both Finite Element Modelling (FEM) techniques as well as experimental trials. A parametric study using simplified 3D FE models was performed to determine their structural integrity under different scenarios. Synchrotron X-Ray tomography (XRT) was used to monitor the behaviour of miniaturized ILW drum-simulants, whilst the latter were subjected to controlled accelerated corrosion in situ. (authors)

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Support of SRS salt-stone regulatory compliance - 15586

The SRS salt-stone Facility is designed and permitted to immobilize and dispose of low-level radioactive and hazardous liquid waste (salt solution) remaining from the processing of radioactive material at the Savannah River Site. The salt-stone Processing Facility (SPF) is permitted as a wastewater treatment facility per the South Carolina Department of Health and Environmental Control Regulations (SCDHEC) South Carolina Hazardous Waste Management Regulations (SCHWMR) R.61-67. The salt-stone Disposal Facility is permitted as a solid waste landfill site, as defined by SCDHEC Regulations R61-107.19. The salt-stone Sampling and Analysis Plan provides the SCDHEC with the chemical and physical characterization strategy for the salt solution and salt-stone waste form. During operation, samples are collected from Tank 50H on a quarterly basis and are analyzed by the Savannah River National Laboratory (SRNL) for over chemical and radioactive components. The analytical results are compared to the salt-stone waste acceptance criteria in a technical report. SRNL also prepares salt-stone samples from the quarterly sample and premix binder materials provided by the SPF to determine the non-hazardous nature of the grout to meet the requirements of the SCDHEC regulation for the 'Characteristic of Toxicity', R.61-79.261.24(b) and the 'Universal Treatment Standards', R.61-79.268.48.4. salt-stone samples are collected, size reduced, packaged, and shipped to an independent United States EPA certified laboratory, or a laboratory that holds an equivalent certification such as one from the National Environmental Laboratory Accreditation Program to perform the EPA Toxicity Characteristic Leaching Procedure (TCLP) extraction of the salt-stone sample. SRNL reviews the results of the TCLP analysis and prepares a report detailing the sample preparation and analysis that is used by the salt-stone Facility to demonstrate the nonhazardous nature of the salt-stone waste form. (authors)

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MAGNOX:BUTEX URANIUM BEARING GLASSES PHYSICAL AND CHEMICAL ANALYSIS DATA PACKAGE

Sellafield Ltd (United Kingdom) has requested technical support from the Savannah River National Laboratory (SRNL) to characterize a series of uranium-bearing, mixed alkali borosilicate glasses [WFO (2010)]. The specific glasses to be characterized are based on different blends of Magnox (WRW17 simulant) and Butex (or HASTs 1 and 2) waste types as well as different incorporation rates (or waste loadings) of each blend. Specific Magnox:Butex blend ratios of interest include: 75:25, 60:40, and 50:50. Each of these waste blend ratios will be mixed with a base glass additive composition targeting waste loadings (WLs) of 25, 28, and 32% which will result in nine different glasses. The nine glasses are to be fabricated and physically characterized to provide Sellafield Ltd with the technical data to evaluate the impacts of various Magnox:Butex blend ratios and WLs on key glass properties of interest. It should be noted that the use of 'acceptable' in the Work for Other (WFO) was linked to the results of a durability test (more specifically the Soxhlet leach test). Other processing (e.g., viscosity ({eta}), liquidus temperature (T{sub L})) or product performance (e.g., Product Consistency Test (PCT) results - in addition to the Soxhlet leach test) property constraints were not identified. For example, a critical hold point in the classification of an 'acceptable glass' prior to processing high-level waste (HLW) through the Defense Waste Processing Facility (DWPF) is an evaluation of specific processing and product performance properties against pre-defined constraints. This process is referred to as Slurry Mix Evaporator (SME) acceptability in which predicted glass properties (based on compositional measurements) are compared to predefined constraints to determine whether the glass is acceptable [Brown and Postles (1995)]. As an example, although the nominal melter temperature at DWPF is 1150 C, there is a T{sub L} constraint (without uncertainties applied) of 1050 C. Any glass which has a T{sub L} predicted value > 1050 C would be classified as unacceptable and the SME product would not be transferred to the melter. As another example, consider durability (as defined by the PCT test) and its related constraints to determine acceptability. If the glass composition yields predicted normalized release values that exceed those associated with the Environmental Assessment (EA) glass (with uncertainties applied) then the glass is deemed unacceptable. The issue of acceptability plays a critical role in high level waste processing but without knowing the pre-defined constraints for the UK HLW system, assessments of acceptability of the glasses to be characterized in this study can not be made. The results of this study will be compared to DWPF constraints to provide a benchmark for determining acceptability. The objective of this task is to provide Sellafield Ltd. with the technical data to evaluate the impacts of various Magnox:Butex blend ratios and WLs on key glass properties of interest. The uranium bearing glasses span a compositional region of interest to Sellafield Ltd. and were physically characterized for key processing and product performance properties as defined in the WFO [WFO (2010)]. One of the specific technical issues (as defined in the WFO) is the potential impact of increasing aluminum concentrations on key properties (in particular viscosity).

36 MATERIALS SCIENCE↗

Modular Thermal Hub For Building Cooling, Heating and Water Heating

A thermally activated hub for modular, scalable, distributed cooling and heating in buildings, which uses working fluids with zero Global Warming Potential (GWP), and can run on thermal energy from combustion, low grade waste heat, or solar energy, was developed and demonstrated in this project. The concept capitalizes on several-fold enhancements in coupled heat and mass transfer possible in microscale passages to remove the primary hurdle that has hindered the implementation of thermally activated heat pumps for more than a century. Cooling capacities of hundreds of watts to tens of kilowatts are possible simply through scaling up of component geometry. In this project, the proof-of-concept 300 W capacity unit was successfully scaled up to 3.5 kW cooling capacity, and packaged into a compact system. These systems can be utilized for a variety of cooling, heating, and air-conditioning applications in residential and commercial buildings. Additional current and potential market opportunities include CCHP applications (military and private sector mobile power generation, and small residential and light commercial stationary power systems (engine, microturbine and fuel cell driven)), solar cooling applications, distributed process waste heat recovery applications, and long-haul transport refrigeration.

HVAC↗

Carbon-14 Geochemistry at the Savannah River Site

Carbon-14 is among the key radionuclides driving risk at the E-Area Low-Level Waste Disposal Facility on the Savannah River Site (SRS). Much of this calculated risk is believed to be the result of having to make conservative assumptions in risk calculations because of the lack of site-specific data. The original geochemical data package (Kaplan 2006) recommended that performance assessments and composite analyses for the SRS assume that 14 C did not sorbed to sediments or cementitious materials, i.e., that C-14 K d value (solid:liquid concentration ratio) be set to 0 mL/g (Kaplan 2006). This recommendation was based primarily on the fact that no site-specific experimental work was available and the assumption that the interaction of anionic 14 C as CO 2 -2 ) with similarly charged sediments or cementitious materials would be minimal. When used in reactive transport equations, the 0 mL/g Kd value results in 14 C not interacting with the solid phase and moving quickly through the porous media at the same rate as water. The objective of this study was to quantify and understand how aqueous 14 C, as dissolved carbonate, sorbs to and desorbs from SRS sediments and cementitious materials. Laboratory studies measuring the sorption of 14 C, added as a carbonate, showed unequivocally that 14 C-carbonate K d values were not equal to 0 mL/g for any of the solid phases tested, but they required several months to come to steady state.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Dose Calculation Methodology and Data for Solid Waste Performance Assessment and Composite Analysis at the Savannah River Site

This report provides a detailed description of the methodology developed to perform dose calculations for E-Area Low Level Waste Facility Performance Assessments and Savannah River Site Composite Analyses. Chapters 2 – 8 give a complete set of equations to be used to calculate dose for individual exposure pathways. The first set of dose scenarios assume that a member of the public establishes residence near the waste site and uses contaminated groundwater or contaminated surface water for personal consumption and to irrigate a garden and pasture where produce and farm animals are raised. Products from the garden and farm animals are used for personal consumption. This scenario applies to both E-Area Performance Assessments and Savannah River Site Composite Analyses. General dose exposure pathways for the resident farmer scenario are: 1. Ingestion pathways described in Chapter 2, 2. Inhalation pathways described in Chapter 3, 3. External exposure pathways described in Chapter 4, and 4. Recreational pathways described in Chapter 5 (Composite Analysis only). Doses from all of the above pathways are directly related to the contaminant concentration in the water. Additional dose scenarios considered for E-Area Performance Assessment assume that an inadvertent intruder encroaches on the waste disposal site after loss of institutional control. General dose exposure pathways considered for the inadvertent intruder are: 1. Ingestion pathways described in Chapter 6, 2. Inhalation pathways described in Chapter 7, and 3. External exposure pathways described in Chapter 8. Doses from all of the intruder pathways are directly related to the contaminant concentration in the buried waste. Special dose considerations related to human consumption of meat and dairy, and treatment of tritium in dose calculations are discussed in Chapter 9. Chapter 10 describes an Excel database named “Radionuclide, Element and Dose Parameter Data Package” that has been created to provide a system for maintaining the data required to perform radionuclide transport and dose calculations. This data includes: Isotope physical parameters and radioactive decay data needed for both transport and dose calculations, Isotope-specific dose coefficients and soil shielding factors associated with exposure pathways, Radionuclide drinking water concentration limits either published by the Environmental Protection Agency or derived from internal dose coefficients to meet the groundwater protection requirements in Department of Energy Order 435.1, Element-specific bio-transfer factors used in dose calculations, Dose equations and values of physical parameters and human factors used in dose calculations, and Key physical constants used in dose calculations.

54 ENVIRONMENTAL SCIENCES↗

Transportation Implications of a Closed Fuel Cycle.

Transportation for each step of a closed fuel cycle is analyzed in consideration of the availability of appropriate transportation infrastructure. The United States has both experience and certified casks for transportation that may be required by this cycle, except for the transport of fresh and used MOX fuel and fresh and used Advanced Burner Reactor (ABR) fuel. Packaging that had been used for other fuel with somewhat similar characteristics may be appropriate for these fuels but would be inefficient. Therefore, the required neutron and gamma shielding, heat dissipation, and criticality were calculated for MOX and ABR fresh and spent fuel. Criticality would not be an issue, but the packaging design would need to balance neutron shielding and regulatory heat dissipation requirements.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Modular Thermal Hub For Building Cooling, Heating and Water Heating

A thermally activated hub for modular, scalable, distributed cooling and heating in buildings, which uses working fluids with zero Global Warming Potential (GWP), and can run on thermal energy from combustion, low-grade waste heat, or solar energy, was developed and demonstrated in this project. The concept capitalizes on several-fold enhancements in coupled heat and mass transfer possible in microscale passages to remove the primary hurdle that has hindered the implementation of thermally activated heat pumps for more than a century. Cooling capacities of hundreds of watts to tens of kilowatts are possible simply through scaling-up of component geometry. In this project, the proof-of-concept 300 W capacity unit was successfully scaled up to 3.5 kW cooling capacity, and packaged into a compact system. These systems can be utilized for a variety of cooling, heating, and air-conditioning applications in residential and commercial buildings. Additional current and potential market opportunities include CCHP applications (military and private sector mobile power generation, and small residential and light commercial stationary power systems (engine, microturbine and fuel cell driven)), solar cooling applications, distributed process waste heat recovery applications, and long-haul transport refrigeration.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Demonstration of the On-the-Fly Shielding Analysis Method: Spent Fuel and Waste Disposition

This report documents work performed supporting the US Department of Energy (DOE) Office of Nuclear Energy (NE) Spent Fuel and Waste Disposition (SFWD) Integrated Waste Management activities under work breakdown structure element 1.08.02.04.01, “Data and Tools Development, Validation, and Maintenance.” In particular, this report fulfills milestone M3SF-21OR020401016, “Implement on-the-fly dose analysis methodology in UNF-ST&DARDS” within work package SF-21OR02040101, “Commercial SNF Characterization - ORNL.” The Used Nuclear Fuel - Storage, Transportation & Disposal Analysis Resource and Data System (UNFST& DARDS) enables automated dose rate calculations for spent nuclear fuel (SNF) transportation packages and storage casks using a Monte Carlo radiation transport code. The explicit method uses a detailed model of the SNF system and its contents. Therefore, a dose rate calculation is required for each as-loaded transportation package or storage cask because the SNF assemblies within a canister typically have unique irradiation characteristics. An alternate method, referred to as the “on-the-fly” shielding analysis method, has been proposed that requires only a set of Monte Carlo dose rate calculations for each transportation packaging/storage cask design. The results of the Monte Carlo dose rate calculations are independent of the SNF assembly irradiation and decay characteristics. The dose rate values may then be combined with the radiation source strength of the SNF assemblies associated with a particular transportation packaging/storage cask design to determine actual dose rates. This report presents on-the-fly dose rate calculations for a representative SNF storage cask and verification of the on-the-fly dose rate calculation results by comparison with reference dose rate calculations using the explicit Monte Carlo dose rate calculation. The on-the-fly shielding analysis method was implemented in UNF-ST&DARDS. A Python program was developed to process the MAVRIC dose rate results obtained by source particle type, energy group, and fuel geometry region. A Python processor created binary files, which were saved as a special UNF-ST&DARDS library for on-the- fly shielding analyses. UNF-ST&DARDS uses the precalculated on-the-fly binary libraries generated by the Python data processor and directly executes the Python code for on-the-fly dose analysis. This Python code unzips the pre-generated binary files mentioned above, reads the data, and combines them with user-specified sources for dose and uncertainty calculations. The Python programs were verified using Excel calculations and by comparison with the values obtained with the MAVRIC post-processing utilities applied to the 3dmap files. This method can currently be used to determine dose rates for as-loaded HI-STORM FW storage casks. The UNF-ST&DARDS analysis wizard for on-the-fly shielding analysis is described in this report.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Sister Rod Destructive Examinations (FY23) Appendix I: SNF Aerosols Released During Rod Fracture

This report documents work performed under the Spent Fuel and Waste Disposition’s Spent Fuel and Waste Science and Technology program for the US Department of Energy (DOE) Office of Nuclear Energy (NE). This work was performed to fulfill Level 3 Milestone M3SF-23OR010201026, “FY23 M3 draft report on results from testing in FY23,” within work package SF-23OR01020102 and is an updated to the work reported in M2SF-23OR010201024, M2SF-22OR010201047, M2SF-21OR010201032, M2SF-19ORO010201026, and M2SF-19OR010201028. As a part of the DOE NE High Burnup Spent Fuel Data Project, Oak Ridge National Laboratory (ORNL) is performing destructive examinations (DEs) of high burnup (HBU) (>45 GWd/MTU) spent nuclear fuel (SNF) rods from the North Anna Nuclear Power Station operated by Dominion Energy. The SNF rods, called sister rods or sibling rods, are all HBU and include four different kinds of fuel rod cladding: standard Zircaloy-4 (Zirc-4), low-tin Zirc-4, ZIRLO, and M5. The DEs are being conducted to obtain a baseline of the HBU rods’ condition before dry storage and are focused on understanding overall SNF rod strength and durability. Fuel rods and defueled cladding will be tested to derive material properties. Although the data generated can be used for multiple purposes, one primary goal for obtaining the post-irradiation examination data and the associated measured mechanical properties is to support SNF dry storage licensing and relicensing activities by (1) addressing identified knowledge gaps and (2) enhancing the technical basis for post-storage transportation, handling, and subsequent disposition.This report documents the status of the ORNL Phase 1 DE activities related to the collection of SNF aerosol particles released during fuel rod fracture in 4-point bending in Phase 1 of the sister rod test program.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Aluminum Clad Spent Nuclear Fuel Task 2: Oxide Layer Radiolytic Gas Generation Resolution Experiment Test Plan

This document presents the test plan for Task 2 of the Aluminum Clad Spent Nuclear Fuel Long Term Dry Storage Technical Issues Action Plan. This task’s overarching goal is the resolution of gas generation resulting from the radiolytic degradation of the oxide layers on aluminum. The uncertainty associated with the build-up of gaseous radiolytic products inside the ASNF storage canisters is one of the dominant technical challenges associated with long term dry storage of aluminum clad fuel. The objectives of the Task 2 test plan are to: 1. Understand how radiation chemistry inside the ASNF dry storage canister impacts extended dry storage performance. 2. Understand the radiation induced mechanisms governing the production of radiolytic gases and alteration of gas composition within a canister. 3. Correlate the observed changes in material properties of ASNF with the radiolytic degradation of aluminum oxide in fill environments of variable moisture and gas composition. 4. Compile a predictive kinetic modeling tool, to provide quantitative mechanistic insight into the in-cask radiation chemistry of ASNF. 5. Interface with the canister modeling activity of Task 3 to deliver degradation rates for package performance of both sealed and vented scenarios.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗