VLPC Single Cassette Cryostat Christmas Tree Temperature as Related to Annulus Flow and LHe Level

Data taken from tests of annulus shield flow versus Christmas tree temperature show that the temperature of the tree is controlled by the annulus flow and the LHe level in the reservoir. Graphs indicating this are shown in Figures 1 and 2. An equation determined from the data taken on 4/19 to model the flow and LHe level dependence of tree temperature is as follows: T = AL + BF + C; T = tree temperature (K); A = -0.0055 (K/%); L = LHe Level (%) - 10% (0.6-inch) < L < 65% (3.9-inch); B = -1.166 (K/scfh air); F = annulus flow (scfh air) - 0.5 < F < 1.0 scfh; and C = 7.889 (K). From the above equation it is evident that shield flow has a significant effect on tree temperature while the percent of LHe in the reservoir is much less significant. The following illustrates the temperature's relative sensitivity to the two variables: {Delta}flow = 0.5 scfh gives {Delta}T = 0.58 K and {Delta}level = 40% LHe gives {Delta}T = 0.22 K. A graph of Temperature Calculated vs. Temperature Measured in Figure 3 shows the degree to which the equation conforms to the data taken on 4/19. This test data is included in the appendix. The measured temperature, calculated temperature, and the percent of error between the two is shown among the data. Figure 3 and the 'Temp.%Error' column in the data indicate the degree of the equation's accuracy. When determining the value of the above equation it is important to consider Figure 4. The graph shows Temperature vs. Annulus Flow data collected on a number of different days. Note that data collected from day to day have similar slopes yet different y-intercepts. This means that the degree to which flow effects temperature remained relatively constant from day to day, yet some unknown variable in temperature control remains. Initially it seems possible that variations in cryostat pressure might be the third variable. But the maximum possible pressure change of 4 psig within the cryostat only accounts for a 0.24 K temperature difference. One other theory is that the GHe used to apply positve pressure to the cassette space is leaking out the cassette top and is causing the change in y-intercepts. A leak in the cassette top would allow warm GHe to enter the cassette volume. Further tests will be done to see if this cassette leak is in fact the problem. The above equation cannot be applied at some instant to determine the annulus flow required at some LHe level to produce a desired tree temperature. Rather its value is that it shows the relative contribution of the two variables to the temperature and the temperature's sensitivity to them. It seems regulation of the tree temperature would best be achieved by providing a feedback loop between temperature and shield flow while maintaining a relatively steady ({+-}5%) LHe level. As one last note, I found that regulating the LHe level with the inlet valve caused disturbances in the cryostat that resulted in temperature drops as great as 0.2 K. To prevent this, when LHe levels fell too low, I would remove the boil-off hose from the regulator for a few minutes until the LHe level was back to a satisfactory level. From this it seems that the LHe level can be controlled by the boil-off regulator with less upset than by adjusting the LHe inlet valve

Strength Test on Optical Fibers to be Used in VLPC

The objective is to determine the strength of the optical fibers to be used in the VLPC cassette. Strength tests were done on optical fibers that are to be used in the VLPC cassette. A number of the fibers will hang vertically and support a suspended copper isotherm. Concern was expressed over whether one fiber could support the entire weight of the isotherm (8 ounces) if uneven shrinkage of the fibers occurs at cryogenic temperatures. The fibers have a polystyrene core and testing done at room temperature showed that one fiber can support the isotherm with a factor of safety of 13.2 before fracture will occur from a uniaxial load. Data in Cryogenic Engineering by Scott shows that the strength of plastics increases (although polystyrene is not listed) as they are cooled. Two tests done to the fibers with liquid nitrogen support this. The safety factor of 13.2 will only increase at cryogenic temperatures. These results were determined through three tests whose summaries are given

U.S. Virgin Islands Energy Road Map: Analysis

This report lays out the strategy envisioned by the stakeholders in the U.S. Virgin Islands, U.S. Department of Energy, and U.S. Department of Interior to achieve the ambitious goal of achieving a 60% reduction in business-as-usual fossil fuel demand by 2025 (60x25) within the electricity sector. This work and supporting analysis provides a framework within which decisions can begin to be made, a concrete vision of what the future might hold, and a guide to determine what questions should follow

Renewable Energy Optimization Report for Naval Station Newport

In 2008, the U.S. Environmental Protection Agency (EPA) launched the RE-Powering America's Land initiative to encourage the development of renewable energy (RE) on potentially contaminated land and mine sites. As part of this effort, EPA is collaborating with the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) to evaluate RE options at Naval Station (NAVSTA) Newport in Newport, Rhode Island. NREL's Renewable Energy Optimization (REO) tool was utilized to identify RE technologies that present the best opportunity for life-cycle cost-effective implementation while also serving to reduce energy-related carbon dioxide emissions and increase the percentage of RE used at NAVSTA Newport. The technologies included in REO are daylighting, wind, solar ventilation preheating (SVP), solar water heating, photovoltaics (PV), solar thermal (heating and electric), and biomass (gasification and cogeneration). The optimal mix of RE technologies depends on several factors including RE resources; technology cost and performance; state, utility, and federal incentives; and economic parameters (discount and inflation rates). Each of these factors was considered in this analysis. Technologies not included in REO that were investigated separately per NAVSTA Newport request include biofuels from algae, tidal power, and ground source heat pumps (GSHP)

Integrating Renewable Energy into the Transmission and Distribution System of the U. S. Virgin Islands

This report focuses on the economic and technical feasibility of integrating renewable energy technologies into the U.S. Virgin Islands transmission and distribution systems. The report includes three main areas of analysis: 1) the economics of deploying utility-scale renewable energy technologies on St. Thomas/St. John and St. Croix; 2) potential sites for installing roof- and ground-mount PV systems and wind turbines and the impact renewable generation will have on the electrical subtransmission and distribution infrastructure, and 3) the feasibility of a 100- to 200-megawatt power interconnection of the Puerto Rico Electric Power Authority (PREPA), Virgin Islands Water and Power Authority (WAPA), and British Virgin Islands (BVI) grids via a submarine cable system

The Layer 0 Inner Silicon Detector of the D0 Experiment

This paper describes the design, fabrication, installation and performance of the new inner layer called Layer 0 (L0) that was inserted in the existing Run IIa Silicon Micro-Strip Tracker (SMT) of the D0 experiment at the Fermilab Tevatron collider. L0 provides tracking information from two layers of sensors, which are mounted with center lines at a radial distance of 16.1 mm and 17.6 mm respectively from the beam axis. The sensors and readout electronics are mounted on a specially designed and fabricated carbon fiber structure that includes cooling for sensor and readout electronics. The structure has a thin polyimide circuit bonded to it so that the circuit couples electrically to the carbon fiber allowing the support structure to be used both for detector grounding and a low impedance connection between the remotely mounted hybrids and the sensors.Comment: 28 pages, 9 figure

Status of 3.9 GHz superconducting RF cavity technology at Fermilab

Fermilab is involved in an effort to assemble 3.9 GHz superconducting RF cavities into a four cavity cryomodule for use at the DESY TTF/FLASH facility as a third harmonic structure. The design gradient of the cavities is 14 MV/m. This effort involves design, fabrication, intermediate testing, assembly, and eventual delivery of the cryomodule. We report on all facets of this enterprise from design through future plans. Included will be test results of single 9-cell cavities, lessons learned, and current status

Production and test results of SC 3.9-GHz accelerating cavity at Fermilab

The 3rd harmonic 3.9GHz accelerating cavity was proposed to improve beam performances for TTF-FEL facility. In the frame of collaboration Fermilab will provide DESY with a cryomodule containing a string of four cavities. In addition, a second cryomodule with one cavity will be fabricated for installation in the Fermilab photo-injector, which will be upgraded for the ILC accelerator test facility. In this paper we discuss the status of the cavity and coupler production and the first result of cavity tests. It is hoped that this project will be completed during the first half of 2007 and the cryomodule delivered to DESY in this time span

Vacuum Systems Consensus Guideline for Department of Energy Accelerator Laboratories

Vacuum vessels, including evacuated chambers and insulated jacketed dewars, can pose a potential hazard to equipment and personnel from collapse, rupture due to back-fill pressurization, or implosion due to vacuum window failure. It is therefore important to design and operate vacuum systems in accordance with applicable and sound engineering principles. 10 CFR 851 defines requirements for pressure systems that also apply to vacuum vessels subject to back-fill pressurization. Such vacuum vessels are potentially subject to the requirements of the American Society of Mechanical Engineers (ASME) Pressure Vessel Code Section VIII (hereafter referred to as the 'Code'). However, the scope of the Code excludes vessels with internal or external operating pressure that do not exceed 15 pounds per square inch gauge (psig). Therefore, the requirements of the Code do not apply to vacuum systems provided that adequate pressure relief assures that the maximum internal pressure within the vacuum vessel is limited to less than 15 psig from all credible pressure sources, including failure scenarios. Vacuum vessels that cannot be protected from pressurization exceeding 15 psig are subject to the requirements of the Code. 10 CFR 851, Appendix A, Part 4, Pressure Safety, Section C addresses vacuum system requirements for such cases as follows: (c) When national consensus codes are not applicable (because of pressure range, vessel geometry, use of special materials, etc.), contractors must implement measures to provide equivalent protection and ensure a level of safety greater than or equal to the level of protection afforded by the ASME or applicable state or local code. Measures must include the following: (1) Design drawings, sketches, and calculations must be reviewed and approved by a qualified independent design professional (i.e., professional engineer). Documented organizational peer review is acceptable. (2) Qualified personnel must be used to perform examinations and inspections of materials, in-process fabrications, non-destructive tests, and acceptance test. (3) Documentation, traceability, and accountability must be maintained for each unique pressure vessel or system, including descriptions of design, pressure conditions, testing, inspection, operation, repair, and maintenance. The purpose of this guideline is to establish a set of expectations and recommendations which will satisfy the requirements for vacuum vessels in general and particularly when an equivalent level of safety as required by 10 CFR 851 must be provided. It should be noted that these guidelines are not binding on DOE Accelerator Laboratories and that other approaches may be equally acceptable in addressing the Part 851 requirements

Renewable Energy Optimization Report for Naval Station Newport

In 2008, the U.S. Environmental Protection Agency (EPA) launched the RE-Powering America's Land initiative to encourage the development of renewable energy (RE) on potentially contaminated land and mine sites. As part of this effort, EPA is collaborating with the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) to evaluate RE options at Naval Station (NAVSTA) Newport in Newport, Rhode Island. NREL's Renewable Energy Optimization (REO) tool was utilized to identify RE technologies that present the best opportunity for life-cycle cost-effective implementation while also serving to reduce energy-related carbon dioxide emissions and increase the percentage of RE used at NAVSTA Newport. The technologies included in REO are daylighting, wind, solar ventilation preheating (SVP), solar water heating, photovoltaics (PV), solar thermal (heating and electric), and biomass (gasification and cogeneration). The optimal mix of RE technologies depends on several factors including RE resources; technology cost and performance; state, utility, and federal incentives; and economic parameters (discount and inflation rates). Each of these factors was considered in this analysis. Technologies not included in REO that were investigated separately per NAVSTA Newport request include biofuels from algae, tidal power, and ground source heat pumps (GSHP)