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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Characterization of Low Level and Intermediate Nuclear Waste: improvements in calorimetric measurement combined radiological modelling - 16144

Since 40 years, calorimetry allows to determine precisely amounts of nuclear material within a container. Combined with gamma spectrometry, calorimetric measurements give plutonium contents with a low level of uncertainty for each isotope. Calorimetry is used in a lot of nuclear facilities all around the world for plutonium or tritium inventories. It is one of the best solutions to estimate the overall quantity of nuclear material on a wide range of mass, from a few milligrams up to kilograms of radionuclides. In the case of drums containing nuclear waste, characterization was very challenging due to complex matrix, volume and low level activities. The measurement time was a real problem with large volume container and organic matrix with high air content. New designs of SETARAM calorimeters allow to measure nuclear material contents in very large container (up to 385 liters) and/or with a very low detection limit (10 μWatt). These new concepts are based on single measurement cell and vacuum chamber for low level uncertainties. The acquisition system and electronic temperature regulation are highly improved to increase the detection limit, accuracy and precision of the measurement. These modern technological developments within the calorimetry field give the promise of faster measurement times and precise measurements. These devices can be used in waste management of nuclear facilities with a better accuracy and lower uncertainties than others techniques. It is a non-destructive and non-intrusive method. There is no matrix effect which can bias the results. Waste can also be in solid, liquid or gas phase. The new calorimeters are able to give amounts of plutonium, tritium or others alpha or beta emitter radionuclides and allow determining the classification of waste (low level or intermediate). A measurement approach combining very large volume calorimeter, gamma spectrometry and radiological modelling will be presented as an integrated automatic waste characterization system. This system with a calculation step is taking into account the gamma emitters contribution on the total thermal power measured within the calorimeter. The aim of the system is to give a precise quantification of the radionuclides in the waste container with a precise value of the total uncertainties. (authors)

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NASA NTRS2011

Use of Dual-Polarization Radar Variables to Assess Low-Level Wind Shear in Severe Thunderstorm Near-storm Environments in the Tennessee Valley

The upgrade of the National Weather Service (NWS) network of S ]band dual-polarization radars is currently underway, and the incorporation of polarimetric information into the real ]time forecasting process will enhance the forecaster fs ability to assess thunderstorms and their near ]storm environments. Recent research has suggested that the combination of polarimetric variables differential reflectivity (ZDR) and specific differential phase (KDP) can be useful in the assessment of low level wind shear within a thunderstorm. In an environment with strong low ]level veering of the wind, ZDR values will be largest along the right inflow edge of the thunderstorm near a large gradient in horizontal reflectivity (indicative of large raindrops falling with a relative lack of smaller drops), and take the shape of an arc. Meanwhile, KDP values, which are proportional to liquid water content and indicative of a large number of smaller drops, are maximized deeper into the forward flank precipitation shield than the ZDR arc as the smaller drops are being advected further from the updraft core by the low level winds than the larger raindrops. Using findings from previous work, three severe weather events that occurred in North Alabama were examined in order to assess the utility of these signatures in determining the potential for tornadic activity. The first case is from October 26, 2010, where a large number of storms indicated tornadic potential from a standard reflectivity and velocity analysis but very few storms actually produced tornadoes. The second event is from February 28, 2011, where tornadic storms were present early on in the event, but as the day progressed, the tornado threat transitioned to a high wind threat. The third case is from April 27, 2011, where multiple rounds of tornadic storms ransacked the Tennessee Valley. This event provides a dataset including multiple modes of tornadic development, including QLCS and supercell structures. The overarching goal of examining these three events is to compare dual ]polarization features from this larger dataset to previous work and to determine if these signatures can be a useful indication of the potential for tornadic activity associated with the amount of low ]level wind shear in the near ]storm environment.

Crowe, Christina C.↗
DOE OSTI2021

FY2020 performance assessment annual review for the E-area low-level waste facility

The Savannah River Site (SRS) E-Area Low-Level Waste Facility (ELLWF) consists of six types of disposal units described in the Performance Assessment (PA) (WSRC, 2008): Low Activity Waste Vault (LAWV), Intermediate Level Vault (ILV), Trenches [Slit Trenches (STs), Engineered Trenches (ETs), and Component-in-Grout (CIG) Trenches], and Naval Reactor Component Disposal Areas (NRCDAs). The ELLWF is a part of the Solid Waste Management Facility (SWMF). SWMF is managed and operated by the SRS Management and Operations prime contractor, Savannah River Nuclear Solutions (SRNS). Within SRNS, the Solid Waste Management (SWM) organization is responsible for operating the SWMF, and the Savannah River National Laboratory (SRNL) is the technical agency responsible for preparing and maintaining the PA. SWMF operations have been performed at SRS since 1952. The mission of the SWMF is to provide storage, processing, disposal, and shipment of radioactive, hazardous, and mixed waste. The SWMF is committed to treat, store, and dispose of these waste products in a manner that protects the environment and the health and safety of the facility worker, the co-located worker, and the offsite general public. Wastes handled in the SWMF include low level waste, transuranic waste, hazardous waste, Toxic Substances Control Act waste, and mixed waste (containing both hazardous and radioactive constituents). The FY2020 PA Annual Review for the ELLWF affirms that the disposal facility continued to operate within the bounds of the current PA and Composite Analysis (CA) baseline and the subsequent SA’s and satisfied all the requirements, conditions, and limitations identified in the 2008 DAS (DOE 2008a), RWMB SRNL_STI-2020-00588 Revision 0 vi (McGill, 2020), and ELLWF Low-Level Waste Acceptance Criteria (SRS-1S, 2014). This annual review affirms that the supporting studies performed in FY2020 do not alter the conclusions of the ELLWF PA (WSRC, 2008) and that there is a reasonable expectation that the ELLWF will meet the performance objectives delineated in DOE Manual 435.1-1 (DOE 2011)

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DOE OSTI2018

Greater Efficiency in the Management of Low-Level Radioactive Material - 18305

The World Nuclear Association is the international organization representing the global nuclear industry. Its mission is to promote a wider understanding of nuclear energy among key international influencers by producing authoritative information, developing common industry positions, and contributing to the energy debate. Membership encompasses companies from the whole fuel cycle (from uranium mining through to decommissioning) as well as support services. Through discussions and survey of the Association's Waste Management and Decommissioning Working Group, it is clear that there is an issue relating to the management of cleared and/or low level radioactive material, particularly during decommissioning where it represents more than 90% of all wastes generated. The group has found that the status quo on the reuse, recycling and disposal of cleared and/or low-level radioactive material arising from the civil nuclear industry (all successfully tested and implemented options) is untenable, and believes that this message should be conveyed to relevant influencers internationally. This message is key and features prominently in a methodological guide being prepared by the group's experts on managing waste from decommissioning which will work through case studies (relating to both technical and financial management) and showcase good practice to support the development of a successful decommissioning strategy. There are currently nearly 450 operating civil nuclear power reactors in the world with many associated nuclear fuel cycle and nuclear research facilities. During the operation and subsequent decommissioning of nuclear facilities, cleared and low-level radioactive material is routinely generated from normal activities, including clothes, rags, metal equipment, concrete structures, etc. For low-level radioactive material, most of this material can be freed from its added radioactivity through survey and simple cleanup (decontamination if necessary). When properly managed and regulated these activities pose no real health issues for people or the environment. It is understandable that there are increasing public demands and expectations for the reuse and recycling of valuable resources, which nuclear - like many other sectors - can no longer ignore. There are efficiencies to be found through technical solutions (resulting in waste volume reductions, better sorting of waste, etc.), which would enable mitigation of environmental impacts and increased preservation of these natural resources. In addition, it will reduce volumes for storage and disposal which are rare resources. There must be a balance struck between the availability of disposal, and recycling and reuse, depending on the outcomes of assessments. Both the advantages in terms of preserving natural resources and disposal capacity should enable the industry to gain credibility with stakeholders. Taking Europe as an example, excellence in the implementation of the reuse and recycling of metals and of disposal of very-low waste, would, if widely shared between countries, no doubt lead to greater efficiency. International and national leaders from industry, regulators and governments should enable the concurrent availability of these three safe management options in each country, worldwide. Whenever an option considered is supported by a solid industrial business case, operators and regulators can (and must) concurrently deploy and operate safe reuse, recycling and disposal. This flexible approach should be deployed; the Association is of the firm conviction that the exclusive commitment to a single option cannot be sound on any grounds. (authors)

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DOE OSTI2013

On-Site Decontamination System for Liquid Low Level Radioactive Waste - 13010

This study is based on an evaluation of purification methods for liquid low-level radioactive waste (LLLW) by using natural zeolite. Generally the volume of liquid low-level waste is relatively large and the specific activity is rather low when compared to other radioactive waste types. In this study, a pilot scale column was used with natural zeolite as an ion exchanger media. Decontamination and minimization of LLLW especially at the generation site decrease operational cost in waste management operations. Portable pilot scale column was constructed for decontamination of LLW on site. Effect of temperature on the radionuclide adsorption of the zeolite was determined to optimize the waste solution temperature for the plant scale operations. In addition, effect of pH on the radionuclide uptake of the zeolite column was determined to optimize the waste solution pH for the plant scale operations. The advantages of this method used for the processing of LLLW are discussed in this paper. (authors)

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DOE OSTI2024

Performance Assessment for the Disposal of Low-Level Waste in the 200 West Area Burial Grounds (Annual Summary Report - FY 23)

This annual review provides the projected dose estimates of radionuclide inventories disposed in the 200 West Area Low-Level Waste Burial Grounds (LLBGs) since September 26, 1988. All the trenches in these burial grounds except two have remained inactive since 2005. The only active trenches that continue to receive low-level and mixed low-level waste are Trenches 31 and 34 that are located in the southern portion of the 218-W-5 Burial Ground. During this reporting period (fiscal year 2023, from October 1, 2022, through September 30, 2023), waste was disposed in these two trenches.

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DOE OSTI2016

Special Analysis for the Disposal of the Transuranic Waste Processing Center Mixed Low-Level Waste Stream at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This special analysis (SA) evaluates whether the Transuranic Waste Processing Center (TWPC) Mixed Low-Level waste stream is suitable for disposal by shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the TWPC Mixed Low-Level waste was meets all U.S. Department of Energy (DOE) Manual DOE M 435.1-1, “Radioactive Waste Management Manual,” Chapter IV, Section P performance objectives. The TWPC Mixed Low-Level waste stream is recommended for acceptance without conditions.

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DOE OSTI2021

Annual Status Report (FY 2020): Performance Assessment for the Disposal of Low Level Waste in the 200 East Area Burial Grounds

This annual review provides the projected dose estimates of radionuclide inventories disposed in the 200 East Area Low-Level Waste Burial Grounds (LLBGs) since September 26, 1988. These estimates are calculated using the original dose methodology developed in the performance assessment (PA) analysis (WHC-SD-WM-TI-730). The estimates are compared with requirements of DOE O 435.1 Chg 1 and performance objectives defined in companion documents DOE M 435.1-1 Chg 1and DOE-STD-5002-2017). All performance objectives are currently satisfied, and operational waste acceptance criteria (HNF-EP-0063) and waste acceptance practices continue to be sufficient to maintain compliance with performance objectives. Inventory estimates and associated dose estimates from future waste disposal actions are unchanged from previous years’ evaluations that indicate potential impacts well below performance objectives; therefore, future compliance with DOE O 435.1 Chg 1 is expected. A new PA study was initiated in fiscal year (FY) 2019 for evaluation of active disposal sites within the 200 East and 200 West Areas (Trench 94 in 200 East; Trenches 31 and 34 in 200 West) due to extended time elapsing between the current annual status report and the original PA for the active disposal sites. The new PA for the active disposal sites is expected to be completed in FY 2021. Within the active burial grounds in the 200 East Area, low-level waste and mixed low-level waste will continue to be disposed of in the dedicated U.S. Navy reactor compartment trench at the 218-E-12B Burial Ground (Trench 94). During this reporting period (FY 2020, from October 1, 2019, through September 30, 2020), two reactor compartments were disposed in Trench 94. Results from sorption experiments are summarized for this reporting period to quantify the efficacy of concrete waste forms in retaining key radionuclides (e.g., technetium-99 and iodine-129). The test durations ranged from 1 to 3 months. Continued groundwater monitoring of the 200 East Area LLBGs indicates no groundwater contamination due to LLBG waste. Current assumptions about future land use at the Hanford Site are consistent with PA analysis1 assumptions of a post-closure facility that will not be degraded by human activity. The LLBGs are located in an area identified for waste management and containment of residual contamination. This area will remain after final environmental remediation and the proposed shrinkage of Hanford Site boundaries to small sections within the 200 East and 200 West Areas in the Central Plateau (DOE/EIS-0391). The current closure plan for the LLBGs (DOE/RL-2000-707) estimates that the 200 East LLBGs will be closed in the 2050 timeframe. The Disposal Authorization Statement, other technical basis documents, and the radioactive waste management basis are of continued adequacy to meet the performance objectives of DOE O 435.1 Chg 1. Overall, there are no substantive changes to primary PA assumptions nor the PA analysis conclusion; therefore, compliance with DOE O 435.1 Chg 1 and the Disposal Authorization Statement is maintained.

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DOE OSTI2019

Use of Automation in Low Level Waste Storage and Management - 19227

The Australian Nuclear Science and Technology Organisation (ANSTO) generates Low Level Waste (LLW) and Intermediate Level Waste (ILW) from various site operations such as the operation of a research Reactor and the manufacture of Molybdenum 99. The Low Level Solid Waste (LLSW) generated is stored at ANSTO before and after conditioning. The current process flow involves the storage of LLSW waste before conditioning on racks, handled using forklifts. When the unconditioned waste is ready for conditioning, it is transferred to another facility, where volume reduction and packaging is carried out. Once conditioned, the waste is placed in further storage, pending dispatch to the proposed Australian National Radioactive Waste Management Facility (NRWMF). A new purpose built facility has been constructed, adjacent to the LLSW processing facility, for the storage and management of LLSW in both unconditioned and conditioned forms. This new facility will streamline the waste management process and significantly enhance the safety and efficiency of the process. In line with international best practises, the new facility utilises automation solutions to minimise the build footprint, and minimise the use of forklifts and other mobile plant. Most importantly, it applies the principle of ALARA (As Low as Reasonably Achievable) to minimise operator activities in areas where radioactive material is stored and eliminates double handling of the waste. The automation for unconditioned waste utilises an Automated Storage and Retrieval System (ASRS), a vertical stacker crane within high density racking, to provide easy storage and retrieval for processing and/or routine inspections. This system allows operators to control it from outside of the storage area whilst utilising integrated software that allows for the required tracking of the unconditioned waste. From the ASRS storage area, unconditioned waste will have a smooth transition to the processing facility which is located adjacent to the ASRS system. Once conditioned, the waste is catalogued and returned to a designated storage area within the new facility using an automated building gantry crane with a target delivery system to eliminate the need for operators in the main storage bay. The waste will be held here in preparation for dispatch to the future repository. The utilisation of the ASRS for the purpose of storing LLSW is an innovative use of automation that will eliminate operators from active areas, reduce dose rates received and integrate with the waste tracking software. Furthermore, the system has significant advantages with operational efficiencies increased, reduced double handling of nuclear waste and maximum use of building footprint. (authors)

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DOE OSTI2019

Development of the Waste Acceptance Criteria for the Idaho National Laboratory Remote-Handled Low-Level Waste Disposal Facility - 19143

The Idaho National Laboratory (INL) Remote-Handled Low-Level Waste (RH LLW) Disposal Facility has been constructed, has received operational approval from the Department of Energy (DOE), and is expected to receive its first waste shipment in FY 2019. The RH LLW Disposal Facility will support the needs of INL and the Naval Reactors Facility (NRF). RH LLW destined for the facility includes waste currently in storage from previous programs and projects conducted at INL; newly generated waste from programs and projects conducted at INL; and waste from NRF spent fuel processing activities. This new facility supports RH LLW disposal needs for the ongoing mission of INL and NRF. Waste to be disposed of at the RH LLW Disposal Facility may exhibit dose rates that range from 0.002 Sv/hr to 600 Sv/hr. Waste types include resins and activated metals as well as surface-contaminated debris generated from existing and new missions. The total number of canisters currently planned for disposal at the RH LLW Disposal Facility is 939 with the possibility of future expansion. The projected waste volume to be disposed of is 3,100 m{sup 3}. The RH LLW Disposal Facility will receive a wide variety of RH LLW and is in preparations to receive its first canisters in FY 2019. Waste acceptance criteria (WAC) and the radioactive waste management basis have been developed and implemented in accordance with the applicable DOE Order. In order to ensure that DOE requirements and guidance were appropriately implemented in the RH LLW Disposal Facility WAC, the project worked closely with the DOE Low Level Waste Disposal Facility Federal Review Group (LFRG) representatives and followed the applicable DOE standard. This paper provides an overview of the development of the WAC, including waste and waste generator certification requirements, for the RH LLW Disposal Facility. The paper illustrates the importance of maintaining strong ties to the development and revision of the RH LLW Disposal Facility Performance Assessment (PA), Documented Safety Analysis, Facility Procedures, Readiness Reviews, DOE Order, and applicable Technical Standards. The paper also provides an overview of the RH LLW Disposal Facility, WAC generator certification requirements, distinctive challenges to acceptance of legacy waste, and the unique approach the RH LLW Disposal Facility has taken to ensure compliance with PA driven limits. (authors)

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DOE OSTI2019

Annual Status Report (FY 2018): Performance Assessment for the Disposal of Low-Level Waste in the 200 East Area Burial Grounds (Rev. 0)

This annual review provides the projected dose estimates of radionuclide inventories disposed in the active 200 East Area Low-Level Waste Burial Grounds (LLBGs) since September 26, 1988. These estimates are calculated using the original dose methodology developed in the performance assessment (PA) analysis. The estimates are compared with performance objectives defined in U.S. Department of Energy (DOE) requirements (DOE O 435.1 Chg 1 and companion documents DOE M 435.1-1 Chg 1 and DOE G 435.1-1). All performance objectives are currently satisfied, and operational waste acceptance criteria and waste acceptance practices continue to be sufficient to maintain compliance with performance objectives. Inventory estimates and associated dose estimates from future waste disposal actions are unchanged from previous years' evaluations that indicate potential impacts well below performance objectives; therefore, future compliance with DOE O 435.1 Chg 1 is expected. Within the active burial grounds, low-level waste and mixed low-level waste currently may be disposed only in the dedicated U.S. Navy reactor compartment trench in the 218-E-12B Burial Ground (Trench 94). Naval reactor compartment disposal at Trench 94 will continue. During this reporting period (fiscal year 2018, from October 1, 2017, through September 30, 2018), two reactor compartments were disposed in Trench 94. Results from multi-year diffusion experiments are summarized for this reporting period to quantify the efficacy of concrete waste forms in retaining key radionuclides (e.g., uranium-238, technetium-99, and iodine-129). The results of sorption experiments initiated in FY 2017 to evaluate sorption coefficients for iodine and technetium are also summarized. The test durations ranged from 1 to 6 months. Continued groundwater monitoring of the 200 East Area LLBGs indicates no groundwater contamination due to LLBG waste. Current assumptions about future land use at the Hanford Site are consistent with PA analysis assumptions of a post-closure facility that will not be degraded by human activity. The LLBGs are located in an area identified for waste management and containment of residual contamination. This area will remain after final environmental remediation and the proposed shrinkage of Hanford Site boundaries to small sections within the 200 East Area and 200 West Area in the Central Plateau. Overall, there are no substantive changes to primary PA assumptions and no changes to the PA analysis conclusion; therefore, compliance with DOE O 435.1 Chg 1 is being maintained.

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DOE OSTI2018

UNREVIEWED DISPOSAL QUESTION EVALUATION: Disposal of the Idaho National Laboratory Radioactive Waste Management Complex Low-Level Waste at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation (UDQE) assesses whether the Idaho National Laboratory (INL) Radioactive Waste Management Complex (RWMC) Low-Level Waste (INEL11006367N, Revision 4 [INL 2017]) is suitable for shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the INL RWMC Low-Level Waste meets all U.S. Department of Energy (DOE) Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P performance objectives (DOE 1999). The INL RWMC Low-Level Waste is recommended for acceptance without conditions.

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DOE OSTI2018

UNREVIEWED DISPOSAL QUESTION EVALUATION: Disposal of the West Valley Demonstration Project Asbestos Contaminated Low-Level Waste Debris at the Area 5 Radioactive Waste Management Site, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation (UDQE) assesses whether the West Valley Demonstration Project (WVDP) Asbestos Contaminated Low-Level Waste Debris (WVDP000000023, Revision 3 [WVDP 2018a]) is suitable for shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the WVDP Asbestos Contaminated Low-Level Waste Debris meets all performance objectives of U.S. Department of Energy (DOE) Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P (DOE 1999). The WVDP Asbestos Contaminated Low-Level Waste Debris is recommended for acceptance with the condition that the total radium-226 (226Ra) waste stream activity shall not exceed 1.4E8 Bq.

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DOE OSTI2018

UNREVIEWED DISPOSAL QUESTION EVALUATION: Disposal of the Los Alamos National Laboratory Regulated Asbestos-Contaminated Low-Level Waste at the Area 5 Radioactive Waste Management Sited, Nevada National Security Site, Nye County, Nevada

This Unreviewed Disposal Question Evaluation (UDQE) assesses whether the Los Alamos National Laboratory (LANL) Regulated Asbestos-Contaminated Low-Level Waste (LANL000000029, Revision 5 [LANL 2017]) is suitable for shallow land burial (SLB) at the Area 5 Radioactive Waste Management Site (RWMS) on the Nevada National Security Site (NNSS). Disposal of the LANL Regulated Asbestos-Contaminated Low-Level Waste meets all U.S. Department of Energy (DOE) Manual DOE M 435.1-1, Radioactive Waste Management Manual, Chapter IV, Section P performance objectives (DOE 1999). The LANL Regulated Asbestos Contaminated Low-Level Waste is recommended for acceptance without conditions.

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DOE OSTI2012

Characterization and Disposition of Legacy Low-Level Waste at the Y-12 National Security Complex - 12133

The Y-12 National Security Complex (Y-12) is concluding a multi-year program to characterize and dispose of all legacy low-level waste (LLW). The inventory of legacy waste at Y-12 has been reduced from over 3500 containers in Fiscal Year (FY) 2000 to 6 containers at the end of FY2011. In addition, the site recently eliminated the inventory of other low-level waste that is greater than 365 days old (i.e., >365-Day LLW), to be in full compliance with DOE Order 435.1. A consistent technical characterization approach emerged for both of these populations of backlogged waste: (1) compile existing historical data and process knowledge and conduct interviews with site personnel; (2) inspect the containers and any tags, labels, or other markings to confirm or glean additional data; (3) with appropriate monitoring, open the container, visually inspect and photograph the contents while obtaining preliminary radiological surveys; (4) obtain gross weight and field non-destructive assay (NDA) data as needed; (5) use the non-public Oak Ridge Reservation Haul Road to ship the container to a local offsite vendor for waste sorting and segregation; (6) sort, drain, sample, and remove prohibited items; and (7) compile final data and prepare for shipment to disposal. After disposing of this backlog, the focus has now turned to avoiding the recurrence of this situation by maintaining low inventories of low-level waste and shortening the duration between waste generation and disposal. An enhanced waste tracking system and monthly metric charts are used to monitor and report progress to contractor and federal site office management. During the past 2 years, the average age of LLW onsite at Y-12 has decreased from more than 180 days to less than 60 days. (authors)

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NASA NTRS1991

Lightning induced currents in aircraft wiring using low level injection techniques

Various techniques were studied to predict the transient current induced into aircraft wiring bundles as a result of an aircraft lightning strike. A series of aircraft measurements were carried out together with a theoretical analysis using computer modeling. These tests were applied to various aircraft and also to specially constructed cylinders installed within coaxial return conductor systems. Low level swept frequency CW (carrier waves), low level transient and high level transient injection tests were applied to the aircraft and cylinders. Measurements were made to determine the transfer function between the aircraft drive current and the resulting skin currents and currents induced on the internal wiring. The full threat lightning induced transient currents were extrapolated from the low level data using Fourier transform techniques. The aircraft and cylinders used were constructed from both metallic and CFC (carbon fiber composite) materials. The results show the pulse stretching phenomenon which occurs for CFC materials due to the diffusion of the lightning current through carbon fiber materials. Transmission Line Matrix modeling techniques were used to compare theoretical and measured currents.

Stevens, E. G.↗
DOE OSTI2023

Assessing Arctic low-level clouds and precipitation from above – a radar perspective

Most Arctic clouds occur below 2 km altitude as revealed by CloudSat satellite observations. However, recent studies suggest that the relatively coarse spatial resolution, low sensitivity, and blind zone of the radar installed on CloudSat may not enable it to comprehensively document low-level clouds. We investigate the impact of these limitations on the Arctic low- level cloud fraction, which is the amount of cloudy points with respect to all points as a function of height, derived from CloudSat radar observations. For this purpose, we leverage highly resolved vertical profiles of low-level cloud fraction derived from downlooking Microwave Radar/radiometer for Arctic Clouds (MiRAC) radar reflectivity measurements. MiRAC has been operated during four aircraft campaigns taking place in the vicinity of Svalbard during different times of the year and covering more than 25,000 km. This allows us to study the dependence of CloudSat limitations on different synoptic and surface conditions.

54 ENVIRONMENTAL SCIENCES↗