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Thermal Issues Associated with the Lighting Systems, Electronics Racks, and Pre-Amplifier Modules in the National Ignition System
No full textThis report summarizes an investigation of the thermal issues related to the National Ignition Facility. The influence of heat sources such as lighting fixtures, electronics racks, and pre-amplifier modules (PAMs) on the operational performance of the laser guide beam tubes and optical alignment hardware in the NE laser bays were investigated with experiments and numerical models. In particular, empirical heat transfer data was used to establish representative and meaningful boundary conditions and also serve as bench marks for computational fluid dynamics (CFD) models. Numerical models, constructed with a commercial CFD code, were developed to investigate the extent of thermal plumes and radiation heat transfer from the heat sources. From these studies, several design modifications were recommended including reducing the size of all fluorescent lights in the NIF laser bays to single 32 W bulb fixtures, maintaining minimum separation distances between light fixtures/electronics racks and beam transport hardware, adding motion sensors in areas of the laser bay to control light fixture operation during maintenance procedures, properly cooling all electronics racks with air-water heat exchangers with heat losses greater than 25 W/rack to the M1 laser bay, ensuring that the electronics racks are not overcooked and thus maintain their surface temperatures to within a few degrees centigrade of the mean air temperature, and insulating the electronic bays and optical support structures on the PAMs
Two-Dimensional Diverging Shocks in a Nonuniform Medium
No full textAn analytic solution is derived from the time evolution of a two- dimensional diverging shock in r - z geometry. The shock propagates through a condensed medium characterized by a Mie-Gruneisen equation of state with a nonzero density gradient in the axial direction
Selection of Actinide Chemical Analogues for WIPP Tests: Potential Nonradioactive Sorbing and Nonsorbing Tracers for Study of Ion Transport in the Environment
No full textChemical characteristics of the actinides (Th, U, Np, Pu, Am) have been studied relative to nonradioactive chemical elements that have similar characteristics in an attempt to identify a group of actinide chemical analogues that are nonradioactive. In general, the chemistries of the actinides, especially U, Np, Pu, and Am, are very complex and attempts to identify a single chemical analogue for each oxidation state were not successful. However, the rationale for selecting a group of chemical analogues that would mimic the actinides as a group is provided. The categorization of possible chemical analogues (tracers) with similar chemical properties was based on the following criteria. Categorization was studied according
Evaluation of 3 Commercially Available, On-Line TOC Analyzers for Monitoring Recycled Water in Semiconductor Processing
No full textRapid detection of excursions in the concentration of organic contaminants in water that is being recycled is crucial to the more widespread acceptance of rinse water recycling as a method of reducing water usage in semiconductor manufacturing. In 1995 SEMATECH'SS116 PTAB (Project Technical Advisory Board) arbitrarily targeted a response time of 30s as the goal for the on-line detection of TOC (Total Oxidizable Carbon) in water - a goal thought to simpliilj the design of water recycling systems (less volume required for water storage in the recycle loop) and lead to more widespread adoption of recycling of spent rinse waters by the US semiconductor industry. A subsequent evaluation of the TOC analyzers commercially available in early 1996 demonstrated that the fastest response times were on the order of three minutes ljllef. 1]. This paper updates the 1996 evaluation of commercially available TOC analyzers by assessing modified versions of two of the previously evaluated analyzers and also anew analyzer that became commercially available in 1997
General Heat Transfer Characterization and Empirical Models of Material Storage Temperatures for the Los Alamos Nuclear Materials Storage Facility
No full textThe Los Alamos National Laboratory's Nuclear Materials Storage Facility (NMSF) is being renovated for long-term storage of canisters designed to hold heat-generating nuclear materials. A fully passive cooling scheme, relying on the transfer of heat by conduction, free convection, and radiation has been proposed as a reliable means of maintaining material at acceptable storage temperatures. The storage concept involves placing radioactive materials, with a net heat-generation rate of 10 W to 20 W, inside a set of nested steel canisters. The canisters are, in placed in holding fixtures and positioned vertically within a steel storage pipe. Several hundred drywells are arranged in a linear array within a large bay and dissipate the waste heat to the surrounding air, thus creating a buoyancy driven airflow pattern that draws cool air into the storage facility and exhausts heated air through an outlet stack. In this study, an experimental apparatus was designed to investigate the thermal characteristics of simulated nuclear materials placed inside two nested steel canisters positioned vertically on an aluminum fixture plate and placed inside a section of steel pipe. The heat-generating nuclear materials were simulated with a solid aluminum cylinder containing .an embedded electrical resistance heater. Calibrated type T thermocouples (accurate to ~ O.1 C) were used to monitor temperatures at 20 different locations within the apparatus. The purposes of this study were to observe the heat dissipation characteristics of the proposed `canister/fixture plate storage configuration, to investigate how the storage system responds to changes in various parameters, and to develop and validate empirical correlations to predict material temperatures under various operating condition
Designs Studies of Low-Aspect Ratio Quasi-Omnigenous Stellarators
No full textSignificant progress has been made in the development of new modest-size compact stellarator devices that could test optimization principles for the design of a more attractive reactor. These are 3 and 4 field period low-aspect-ratio quasi-omnigenous (QO) stellarators based on an optimization method that targets improved confinement, stability, ease of coil design, low-aspect-ratio, and low bootstrap current
Evaluation of Margins in the ASME Rules for Defining the P-T Curve for a RPV
No full textlight water reactor
Neural Network Modeling of Weld Pool Shape in Pulsed-Laser Aluminum Welds
No full textA neural network model was developed to predict the weld pool shape for pulsed-laser aluminum welds. Several different network architectures were examined and the optimum architecture was identified. The neural network was then trained and, in spite of the small size of the training data set, the network accurately predicted the weld pool shape profiles. The neural network output was in the form of four weld pool shape parameters (depth, width, half-width, and area) and these were converted into predicted weld pool profiles with the use of the actual experimental poo1 profiles as templates. It was also shown that the neural network model could reliably predict the change from conduction-mode type shapes to keyhole-mode shapes
HRIBF Tandem Accelerator Radiation Safety System Upgrade
No full textThe HRIBF Tandem Accelerator Radiation Safety System was designed to permit experimenters and operations staff controlled access to beam transport and experiment areas with accelerated beam present. Neutron-Gamma detectors are mounted in eaeh area at points of maximum dose rate and the resulting signals are integrated by redundan~ circuitry; beam is stopped if dose rate or integrated dose exceeds established limits. This paper will describe the system, in use for several vears at the HRIBF, and discuss changes recently made to modernize the system and to make the system compliant with DOE Order 5480.25 and related ORNL updated safety rules
Natural Gas Monthly August 1998
No full textThe Natural Gas Monthly (NGM) highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. Explanatory notes supplement the information found in tables of the report. A description of the data collection surveys that support the NGM is provided. A glossary of the terms used in this report is also provided to assist readers in understanding the data presented in this publication