Extrusion of tritium and D-T pellets for ITER fueling

Abstract

As part of the International Thermonuclear Engineering Reactor (ITER) plasma fueling development program, Oak Ridge National Laboratory (ORNL) has fabricated a pellet injection system to test the mechanical and thermal properties of extruded tritium. This repeating, single-stage, pneumatic injector, called the Tritium-Proof-of-Principle Phase II (TPOP-II) Pellet Injector, has a piston-driven mechanical extruder and is designed to extrude and accelerate hydrogenic pellets sized for the ITER device. The TPOP-II program has the following development goals: evaluate the feasibility of extruding tritium and deuterium-tritium (0-T) mixtures for use in future pellet injection systems; determine the mechanical and thermai properties of tritium and D-T extrusions; integrate, test, and evaluate the extruder in a repeating, single-stage light gas gun that is sized for the ITER application (pellet diameter -7 to 8 mm); evaluate options for recycling propellant and extruder exhaust gas; evaluate operability and reliability of ITER prototypical fueling systems in an environment of significant tritium inventory that requires secondary and room containment systems.In tests with deuterium feed at ORNL, up to 13 pellets have been extruded at rates up to 1 Hz and accelerated to speeds of 1 .O to 1.1 km/s, using hydrogen propellant gas at a supply pressure of 65 bar. Initially, deuterium pellets 7.5 mm in diameter and 11 mm in length were producedthe largest cryogenic pellets produced by the fusion program to date. These pellets represent about a 10% density perturbation to ITER. Subsequently, the extruder nozzle was modified to produce pellets which are nearly 7.5 mm right circular cylinders. Tritium and D-T pellets have been produced in experiments at the Los Alamos National Laboratory Tritium Systems Test Assembly (TSTA). Hydrogenic pellets will be used in ITER to sustain the fusion power in the plasma core and may be crucial in reducing first-wall tritium inventories by a process called isotopic fueling in which tritium-rich pellets fuel the burning plasma core and deuterium gas fuels the edge.

Calibration of the Fundamental Plane Zero Point in the Leo I Group and an Estimate of the Hubble Constant

“…We estimate the mean value inside 16 ′′ to beσ = 140 ± 10 km s −1 , in agreement with the value ofσ = 138 ± 10 km s −1 reported by Fisher, Franx, & Illingworth (1996). The rotation around the minor axis is about 80 ± 10 km s −1 and there is no rotation around the major axis (Busarello et al 1996;Fisher 1996), and hence we obtain σ = 156 ± 11 km s −1 . The corrected Mg 2 from Fisher et al (1996) is 0.281 but this should be compared with 0.249 from Worthey, Faber, & Gonzalez (1992).…”

“…′′ 5 found in the B band by Busarello et al (1996). The central velocity dispersion along the minor and major axes is 160 ± 5 km s −1 but then drops to about 100 km s −1 at a radius of 16 ′′ (Busarello et al 1996;Fisher 1996). We estimate the mean value inside 16 ′′ to beσ = 140 ± 10 km s −1 , in agreement with the value ofσ = 138 ± 10 km s −1 reported by Fisher, Franx, & Illingworth (1996).…”

“…The velocity dispersion reported by Fisher et al (1996) isσ = 103 km s −1 with an estimated uncertainty of 10 km s −1 . There is no rotation around the minor axis whereas the rotation around the major axis shows a steady increase out to 27 ′′ (Fisher 1996). We adopt the rotation velocity at 10 ′′ of 57 km s −1 and assign a large uncertainty of 20 km s −1 to this value.…”

Multicomponent Polymeric Materials

“…The second breakthrough was the addition of thermoplastics such as poly(methyl methacrylate), poly(vinyl acetate) (106), polyester urethanes and/ or long-chain fatty acid capped terephthalic acid-based (polyester oligomers (107), called low-profile additives (LPAs). (Oligomers are low molecular weight polymers, generally a few thousand g/mol; see Section 3.1.1.)…”