Surface-exposure dating of moraine boulders and numerical paleoglacier modeling yield the first numerical ages for the local Last Glacial Maximum (LGM) in the state of New Mexico and the southernmost Rocky Mountains, and the first glacier-based paleoclimate estimates for that region. Analysis of cosmogenic 10Be in samples from ten moraine boulders indicates that glaciers in the Winsor Creek drainage in the southern Sangre de Cristo Mountains occupied their LGM positions until ∼21.2 ± 2.0 ka, and likely remained near those positions until about 18.3 ± 1.3 ka. Application of a coupled energy/mass balance and ice-flow model to the reconstructed paleoglaciers indicates that temperature depressions of 8.6–9.0 °C from present temperatures would have been necessary to sustain glaciers in the drainage at their last glacial maximum extents, assuming precipitation amounts and seasonality were no different from modern. Model uncertainly in these estimates is approximately ±1.5 °C. Combining glacier-model output with climate-model output interpolated to the study region suggests that the LGM glaciers in the drainage were likely sustained by a temperature depression of ∼8 °C from modern conditions, coupled with an increase of ∼10–25% in precipitation, at least during the fall-through-spring seasons. Such an increase in accumulation season precipitation is consistent with previous suggestions of enhancement of Pacific-sourced cyclonic precipitation due to southward displacement of the LGM mean winter storm track across the western United States and/or of increased intensity and penetration of Pacific atmospheric rivers into the continent at the LGM.

A combination of 10Be surface-exposure dating of glacially transported boulders and glacially polished bedrock, and numerical modeling of the-600 km2 Late Pleistocene icefield complex in the northern Medicine Bow Mountains of Wyoming, USA, constrains the timing and climate forcing of the local last glacial maximum (LLGM) and the subsequent deglaciation in the range. The chronology reported here indicates initial recession of the-100 km2 Libby Creek glacier on the east side of the complex from its terminal moraine at 20.7 & PLUSMN; 2.8 ka, followed by length reduction of 38% by 18.0 & PLUSMN; 0.8 ka and 75% by 14.7 & PLUSMN; 0.4 ka. By 14.2 & PLUSMN; 0.3 ka, the icefield had nearly completely disappeared although there is evidence of two subsequent standstills or minor readvances at-11.5 & PLUSMN; 0.5 ka and-10.5 & PLUSMN; 0.3 ka. Results of numerical glacier-modeling experiments suggest that the LLGM was associated with temperatures 6.0 degrees C colder than present with an uncertainty of about & PLUSMN;1.7 degrees C, assuming no change from modern precipitation. If precipitation differed at the LLGM, over a range from half to twice modern, the temperature depression necessary to sustain the icefield complex could have been as much as 8.0 & PLUSMN; 1.7 degrees C or as little as 3.1 & PLUSMN; 1.7 degrees C respectively. As most available proxies and climate-model output suggest mildly decreased precipitation at the LLGM, a temperature depression of somewhat more than 6.0 degrees C is the most likely scenario. Model experiments further suggest that nearly complete deglaciation by 14.2 & PLUSMN; 0.3 ka involved only a-1.7 degrees C rise from LLGM temperature, assuming no change in precipitation. The sensitivity of the icefield complex to such limited warming reflects its plateau-like hypsometry, which makes it particularly sensitive to changing equilibrium-line altitude. While the precise chronology of deglaciation remains open to interpretation, most of the ice loss preceded the North Atlantic Bolling-Allerod interval (-14.7-12.9 ka), suggesting that global atmospheric CO2 and rising summer insolation were the dominant forcings of ice retreat.

Carlsbad Cavern and Lechuguilla Cave are large limestone caves located within Carlsbad Caverns National Park, southeastern New Mexico, USA. Both caves feature numerous pools that enable sampling of locally perched water bodies at different depths within the thick vadose zone. Isotopic analysis of multiple water samples from both caves revealed clear evidence of bomb-pulse tritium (up to 6.1% bomb-pulse maximum, BPM) and Cl-36 (up to 5.2% BPM) in many pools. In all cases, isotope concentrations were well below peak bomb-pulse levels, indicating complex mixing processes between the ground surface and the cave pools. The deepest bomb-pulse detections in the caves indicate vertical transport velocities of up to 6-9 m/yr for the fastest flowpaths. Peak tritium levels in Lechuguilla are lower than those in Carlsbad, potentially due to mixing and dilution via vapor phase exchange through the high relative humidity cave atmosphere, processes that may be less effective in Carlsbad's drier atmosphere. Peak Cl-36/Cl ratios in Carlsbad are lower than those in Lechuguilla, possibly due to dilution by introduced stable Cl- associated with tourist developments in the cave. Stable isotope results demonstrate the different evaporative regimes of the two caves, caused by Carlsbad Cavern's large natural entrance, in contrast to Lechuguilla's complete lack of a present-day natural entrance. Our results bolster the use of speleothem records for paleoclimate reconstruction, demonstrating the effective transmission of the bomb pulse signal to depths of hundreds of meters within a few decades. At the same time, the pronounced and variable impact of evaporation on some samples shows the potential importance of local conditions on specific sample results.

An experimental system was designed and optimized to acquire real-time electrical resistance of the monitors during annealing. The system was then used to anneal irradiated silicon carbide (SiC) monitors. The altered resistance of the SiC monitors between the first heating cycle and the mean of the heating and cooling cycles that followed was found to significantly change when the annealing temperature exceeded the peak irradiation temperature. This was validated using nine irradiated SiC monitors annealed over two heating and cooling cycles. Of these SiC monitors, three were annealed for the first time. The remaining six monitors were already annealed, but four of these were found to contain residual defects that resulted in reasonable estimates of peak irradiation temperatures. Those estimated peak irradiation temperatures were statistically indifferent from the manual isochronal annealing method temperatures. The results demonstrate a preliminary potential for the two-cycle approach to replace or augment the current manual post-irradiation examination (PIE) process for extracting SiC monitor peak irradiation temperature.

In this paper we use a numerical glacier-climate model, a detailed photogrammetric survey and lichenometry to reconstruct small palaeoglaciers on Ben Nevis and surrounding mountains in western Scotland. These glaciers would have been sustained under a climate where the mean annual air temperature was -1.0 degrees C to -2.0 degrees C compared to present-day values either with or without a decrease in precipitation amount of 10-30%. Historical meteorological data show that these air temperatures were reached on Ben Nevis in the latter part of the 19th century. Although we have no data on the age of these small glaciers, palaeoclimate reconstructions suggest that such conditions almost certainly existed several times during the Holocene in Scotland; the last time being the Little Ice Age of the 16th to 19th Centuries. We argue from this that small Scottish glaciers may have been able to develop in high sheltered cirques at many times during the Holocene and that the glacial history of Scotland therefore requires revision.

The geologic record of mountain glaciations is a robust indicator of terrestrial paleoclimate change. During the last glaciation, mountain ranges across the western US hosted glaciers while the Cordilleran and Laurentide ice sheets flowed to the west and east of the continental divide, respectively. Records detailing the chronologies and paleoclimate significance of these ice advances have been developed for many sites across North America. However, relatively few glacial records have been developed for mountain glaciers in the northern Rocky Mountains near former ice sheet margins. Here, we report cosmogenic beryllium-10 surface exposure ages and numerical glacier modeling results, which show that mountain glaciers in the northern Rockies abandoned terminal moraines after the end of the global Last Glacial Maximum around 17–18 ka and could have been sustained by −10 to −8.5 ∘C temperature depressions relative to modern assuming similar or less than modern precipitation. Additionally, we present a deglacial chronology from the northern Rocky Mountains that indicates while there is considerable variability in initial moraine abandonment ages across the Rocky Mountains, the pace of subsequent ice retreat through the late glacial exhibits some regional coherence. Our results provide insight on potential regional mechanisms driving the initiation of and sustained deglaciation in the western US, including rising atmospheric CO2 and ice sheet collapse.

Since the U.S. Department of Energy Office of Nuclear Energy initiated the Nuclear Energy University Program (NEUP) in 2009, there are 29 NEUP projects focusing on high-temperature gas-cooled reactor (HTGR) research up to July 2022. The resultant research product, either experimental or computational, were published as final NEUP reports, journal articles and conference proceedings. However, these federally funded products have been scattered and sometimes cannot be easily accessed. To improve access to this valuable HTGR validation data and optimize the return on the significant investment made by the Department of Energy, the Advanced Reactor Technologies (ART) Gas-Cooled Reactor (GCR) program started a survey of completed and ongoing HTGR NEUP projects to develop a public-access database specific for HTGRs applications that can be used to retrieve computational fluid dynamics and system code validation data. This effort will help guide future NEUP-funded research, define new state of the ART Phenomena Identification and Ranking Table (PIRT), and promote the usage of this data in the codes validation matrices. This report provides an overview of the NEUP-funded HTGR-related research projects from Fiscal Year (FY) 2009–2021 and identifies validation knowledge gaps still existing in HTGR thermal-fluid research. A preliminary data platform has been developed for the 29 NEUP projects investigating HTGR thermal hydraulics, including their final reports as well as the available scientific publications. As an ultimate goal for this work, the ART-GCR program will create a central database at Idaho National Laboratory to identify, organize, and store these datasets generated by experimental investigations or computational models, experimental facility descriptions, and publicly-available academic products from the HTGR-related NEUP projects and provide future guidance for the storage and transmission of important project documentations for later NEUP projects as well.

Low-enriched ( similar to 19.75% 235 U) U-10Mo(wt%) foils were evaluated for both mechanical and thermophysical properties to establish baseline characteristics prior to irradiation testing. Cast U-10Mo ingots were sequentially hot and cold rolled to two different final foil thicknesses, resulting in different levels of cold work being present in the finished foils. The mechanical response of the U-10Mo foils was evaluated in the temperature range of 293-623 K. Increasing test temperatures resulted in decreases of both yield and ultimate tensile strength. Comparison of results to earlier work performed on depleted U-10Mo rolled foils indicates that the material in this study has lower strength and increased ductility. However, a comparison of the two different foil thicknesses in this study found that they were nearly identical in yield and ultimate tensile strength, differing by only 10-20 MPa ( < 2%). Thermal conductivity was calculated from the measurements of specific heat, linear thermal expansion, and thermal diffusivity from 323 to 1273 K on both thicknesses of the foils. These data were approximately 5-10% lower than previously published data above 573 K and were similar to data for temperature ranges below 573 K. Differences are likely related to differences in grain size and/or impurity content and variation in fabrication history. (c) 2022 Elsevier B.V. All rights reserved.

The injection well stimulation project at the Raft River geothermal field tests the effect of long-term cold water injection and high pressure injection on well injectivity, improvements to which could reduce operating costs. The primary data for analysis and interpretation of the injection test are step-rate flow tests run before each new phase of the injection. These tests were analyzed using a combination of standard pump-test analytical solution methods and methods developed expressly for the observed conditions. The stepped rate injection tests, combined with long-term flow and pressure response data suggest that the well is located within a fractured formation of low transmissivity but high storativity. These calculated parameters appeared to increase with pressure during the first injection test and the higher values were reproduced during the second stepped rate test. Calculated transmissivity and storativity are on the order of 4E-5 m cm and 1E-4 m Pa, respectively. The apparent pressure dependence of fitted hydraulic parameters may reflect near-well fracture compliance that increased the effective radius of the wellbore during the first test. While the type curve fit analysis also suggests that the reservoir behaves as a uniformly fractured reservoir with a radial flow regime, the hydraulic parameters indicate that condition may exist only a very limited distance (<10 m) from the well. Longer-term pressure response suggests that flow in the system effectively reaches steady state in a period of less than a day, which may reflect pressure stabilization resulting from pressure-dependent permeability or a region of much higher permeability located with a few meters of the well. The transmissivity estimates obtained from this analysis, converted to approximate fracture density and aperture, provide useful constraints on the distance to which the thermal front may migrate from the well during the cold water injection phase of the stimulation project. We estimate that the cooling front will migrate less than a tenth of a kilometer over an approximately one-year injection period. The effects of that cooling, however, may be substantial, because increases in permeability have maximum effect nearest the well. INTRODUCTION Whether to increase productivity of existing hydrothermal reservoirs, or to engineer new geothermal reservoirs, methods of stimulating wells to increase productivity are essential to expansion of geothermal energy. To provide a detailed study of well response to stimulation on the edges of an active hydrogeothermal system, the Department of Energy Geothermal Technology Program is sponsoring an Enhanced Geothermal System study at the Raft River Geothermal Reservoir in southern, Idaho. An existing well at that location, well RRG-9, was drilled to the depth of other productive reservoir wells but proved to have injectivity too low for economic use as either a production well or cold water injection well. The project involves application of a series of stimulation methods to well RRG-9 and detailed monitoring of the well and reservoir to better understand reservoir response to stimulation. The stimulation methods include long-term cold water injection at a variety of flow rates and injection temperatures, aimed at improving permeability by cooling and contraction of the fractured rock host formation, followed by high-pressure injections designed to alter permeability via application of fluid pressures that exceed the fracture gradient. Methods of monitoring the reservoir include high-resolution temperature logging within the well at all times, via distributed temperature sensing, seismic monitoring, periodic borehole televiewer logging, periodic stepped flow rate tests and tracer injections before and after stimulation efforts. In this paper, we discuss initial analysis of the thermal stimulation efforts in well RRG-9. Novel methods of analysis are discussed and put into perspective using numerical simulation of poroelastic behavior in the reservoir. The results should provide useful information for further analysis of thermal stimulation effects in geothermal reservoirs. BACKGROUND Raft River Geothermal Area The Raft River geothermal reservoir is located in Cassia County Idaho approximately 6 miles north of the Utah/Idaho border near the town of Malta (Figure 1). This site was heavily studied by the U.S. Department of Energy from 1975 to 1982 and was the testing site of the first commercial scale binary (isobutene) cycle geothermal power plant in the world. Presently this site is owned and operated by U.S. Geothermal and is producing power from a 13-MW (nominal) binary isopentane power system. The geologic structure in the Raft River geothermal area has been extensively studied using geophysical methods, surface mapping, aerial photography and core lithologic descriptions of subsurface core materials. The Raft River geothermal site is located near the southern end of the Raft River north-south trending valley (Figure 2). This valley is characterized by high-angle normal faulting, lowangle faulting emplacing younger over older rocks, moderate plutonism, and the presence of discontinuous metamorphic terrains (Allman et al., 1982). Beneath the surface alluvium, the Salt Lake Formation is a thick (~1200 meter) poorly consolidated deposit consisting of siltstone and sandstone. Underlying this formation is a 150 meter metamorphized unit, called the metasediments, consisting of sub-units of schist and quartzite. The base rock is a Precambrian adamellite. The western side of the valley has been down dropped along listric faults in the Bridge and Horse Well Fault zones through the Salt Lake Formation. These faults dip 60 to 80

The geologic record of mountain glaciation is one of the most sensitive archives of terrestrial climate change during the late Quaternary Period. Pleistocene glacial deposits are exceptionally well preserved in the Great Basin of North America where they are found in close proximity to shoreline deposits of coeval paleo-lakes, representing a unique opportunity to investigate paleoclimate change using both hydrologic systems. Mountain glaciers advanced across much of the Wasatch Range, Utah during the same general time interval when Lake Bonneville expanded in the adjacent Bonneville Basin. Here we present a range-wide Latest Pleistocene glacial history for the Wasatch Range based on 22 new and 41 recalculated cosmogenic 10Be surface exposure ages, and reconstruct glaciers and climate for the Last Glacial Maximum (LGM) and Lateglacial periods. Our results indicate three distinct, range-wide phases of glaciation in the Wasatch including the Pinedale 1 (ca. 21–20 ka), Pinedale 2 (ca. 17.5 ka) and Pinedale 3 (ca. 15 ka). Our modeling results indicate that the Pinedale 1 advance, near the end of the global LGM, was primarily driven by decreased annual temperatures with little to no change in precipitation as compared to modern. Wasatch glaciers appear to have reoccupied near maximum positions after the end of the LGM during the Pinedale 2, responding to increased precipitation in concert with rising lake levels across Western North America, and then retreated from ice-distal positions near ca. 17.5 ka. Wasatch glaciers occupied recessional positions at approximately half their maximum lengths during Pinedale 3 until ca. 15 ka, followed by rapid (i.e. several millennia) deglaciation. Our glacial chronologies establish that Wasatch glaciers responded synchronously across the range to global and regional climate forcings during the Latest Pleistocene. The new Wasatch glacial chronology, combined with global glacial chronologies and paleoclimate proxies from Western North America, suggest glacier change was driven by a combination of long-term global temperature forcing as well as regional to local modifications in precipitation.

Corn stover dry matter loss effects variability for biofuel conversion facility and technology sustainability. This research seeks to understand the dynamic mechanisms of the thermal system, organic matter loss, and microbial heat generation in corn stover storage operations through system dynamics, a mathematical modeling approach, and response analysis to improve the system performance. This study considers epistemic uncertainties including cardinal temperatures of microbial respiratory activity, specific degradation rate, heat evolution per unit substrate degraded, and thermal conductivity in corn stover storage reactors. These uncertainties were managed through calibration, a process of improving the agreement between the computational and benchmark experimental results by adjusting the parameters of the model. Model calibration successfully predicted the temperature of the system as quantified by the mean absolute error, 0.6°C, relative to the experimental work. The model and experimental dry matter loss after 30 days of storage were 5.1% and 4.9 ± 0.28%. The model was further validated using additional experimental results to ensure that the model accurately represented the system. Model validation obtained a temperature mean absolute relative error of 0.9 ± 0.3°C and dry matter loss relative error of 3.1 ± 1.5%. This study presents a robust prediction of corn stover storage temperature and demonstrates that an understanding of carbon sources, microbial communities, and lag-phase evolution in bi-phasic growth are essential for the prediction of organic matter preservation in corn stover storage systems under environment's variation.

Silicon carbide (SiC) monitors provide a means of measuring peak irradiation temperature of experiment capsules in nuclear irradiation experiments. Neutron irradiation of a SiC monitor causes permanent lattice changes that are removed by annealing via heating to a temperature that exceeds the peak irradiation temperature. The annealing process results in changes to SiC physical characteristics that can be observed during the annealing process. This paper presents results of a method aimed at using electrical resistance, measured during a two-pass heating – cooling cycle as a means of recovering the irradiation temperature of a SiC monitor. Results indicate that the relationship between resistance and temperature of a SiC monitor shows a significant change in slope when the peak irradiation temperature is reached. This demonstrates the potential for this method to replace the current manual, and lengthy, process of post irradiation examination used to extract the peak irradiation temperature from irradiated SiC monitors.

The EGS Collab project is developing ~10-20 m-scale field sites where fracture stimulation and flow models can be validated against controlled, small-scale, in-situ experiments. The first multi-well experimental site was established at the 4850 level in the Homestake Mine, where hydraulic fractures were created at an injection well drilled sub-horizontal from the drift. Ten tracer tests were conducted to characterize fracture flow pathways during the second hydraulic characterization test for 164’ Notch (October 24 to November 14, 2018) during steady state injection of 400 ml/min at the injection well. Injected tracers include DNA, C-dots (fluorescein nano particles), fluorescein, rhodamine-b, sodium chloride, lithium bromide and cesium iodine. The tracers have been detected in three flowing wells located about 7.5 to 9 meters away from the injection interval. The tracer breakthrough curves from these locations have been adjusted to account for the residence time in the injection and production tubing. At the time of writing this paper, only the fluorescent C-dots, rhodamine-b and chloride have been analyzed for concentration vs time/volume at the production wells. Results from early testing have been re-analyzed as to the; amount and location of injected water recovery and the mass of tracer recovered.

The second Advanced Gas Reactor irradiation (AGR-2) featured UCO tristructural isotropic (TRISO)-coated particle fuel and, for comparison purposes, UO2 TRISO fuel. Particles from three UCO fuel compacts and one UO2 fuel compact were chosen for analysis of kernel swelling and buffer shrinkage. Both kernel swelling and buffer shrinkage are common elements of TRISO fuel performance models. More recently, the AGR program has determined that buffer shrinkage may impact the integrity of the inner pyrolytic carbon (IPyC) layer, which may impact SiC layer integrity (particularly during high-temperature heating tests). Therefore, measurements of buffer irradiation-induced shrinkage may be useful in improving existing models and developing new models that capture buffer-IPyC-SiC-fission product interactions observed in recent AGR post-irradiation examination (PIE). TRISO particles were mounted in epoxy, ground, polished, and imaged via optical microscopy in four separate iterations. Each of the four iterations revealed progressively deeper cross sections within the particles. Images collected from each iteration were analyzed for the circumferences/radii of the kernel, buffer, IPyC, and SiC. Spheres were fit to each set of measurements to generate spherical radii representative of the components of the fuel particle. From these radii, volumes were computed and compared to the as-fabricated volumes. UCO kernel swelling was similar among the three AGR-2 compacts ranging from approximately 28 to 32%. This is only slightly higher swelling than was measured in an earlier study of an AGR-1 compact. However, the burnup at which this swelling occurred in AGR-2 was lower than in AGR-1, indicating a faster swelling rate for the AGR-2 kernels for the irradiation conditions covered by these compacts. The AGR-2 UO2 kernel swelling was less, at 9.9%, comparable to other studies of UO2 kernel swelling. While AGR-2 UCO and UO2 kernels demonstrated different rates of swelling, the extent of buffer shrinkage was similar among the two fuel types, ranging from 24-28%. For comparison, a prior study showed that AGR-1 Compact 1-3-1 experienced 39% buffer shrinkage. A commonly-observed post-irradiation particle morphology is where the buffer pulls away from the IPyC (at least in some regions of the particle). Besides the possibility of the buffer degrading the IPyC when it pulls away from the IPyC, this gap is significant because it may also reduce heat transfer within the particle. Average AGR-2 buffer-IPyC gaps were similar for the UCO and UO2 particles, ranging from 22.2 to 26.0 µm. This is similar to what was measured for AGR-1 Compact 1-3-1.