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Various perfluorinated materials are used at the Princeton Plasma Physics Laboratory in support of the Deuterium-Tritium experimental program on the Tokamak Fusion Test Reactor (TFTR). For example, SF{sub 6} is used as a high dielectric gaseous insulator in the Neutral Beam sources, and Krytox, a perfluorinated polyether, is used as a lubricant in vacuum pumping systems. Each of these materials is robust and stable in the applications for which they are designed but may be a source of trouble when used in tritium systems. This paper reports on the observations made and experience gained operating tritium systems under conditions which degrade these perfluorinated materials. The possible degradation mechanisms and products are described, and the effect on the equipment and instrumentation is described. These observations have led to the conclusion that under certain circumstances perfluorinated materials are not suited for tritium service because of the degradation products from tritium decay and/or process conditions. 11 refs., 1 fig., 1 tab.

TFTR has begun its campaign to study deuterium-tritium fusion under reactor-like conditions. Variable amounts of deuterium and tritium neutral beam power have been used to maximize fusion power, study alpha heating, investigate alpha particle confinement, and search for alpha driven plasma instabilities. Additional areas of study include energy and particle transport and confinement, ICRF heating schemes for DT plasmas, tritium retention, and fusion in high βp plasmas. The majority of this work is done in the TFTR supershot confinement regime. To obtain supershots, extensive limiter conditioning using helium fueled ohmic discharges and lithium pellet injection into ohmic and neutral beam heated plasmas is performed, resulting in a low recycling limiter. The relationship between recycling and core plasma confinement has been studied by using helium, deuterium and high-Z gas puffs to simulate high recycling limiter conditions. These studies show that confinement in TFTR supershots is very sensitive to the influx of neutral particles at the plasma edge.

The high power D-T experiments on the tokamak fusion test reactor (TFTR) at the Princeton Plasma Physics Laboratory commenced in November 1993. During initial operation of the tritium systems a number of start-up problems surfaced and had to be corrected. These were corrected through a series of system modifications and upgrades and by repair of failed or inadequate components. Even as these operational concerns were being addressed, the tritium systems continued to support D-T operations on the tokamak. During the first six months of D-T operations more than 107 kCi of tritium were processed successfully by the tritium systems. D-T experiments conducted at TFTR during this period provided significant new data. Fusion power in excess of 9 MW was achieved in May 1994. This paper describes some of the early start-up issues, and reports on the operation of the tritium system and the tritium tracking and accounting system during the early phase of TFTR D-T experiments.

Palladium and LaNi5-xAlx (x=0.30, 0.75, 0.85), which form reversible hydrides, are used for tritium processing and storage in the Savannah River Site (SRS) tritium facilities. As part of a program ...

Two plateaux are observed in the desorption isotherm for palladium hydride: a lower plateau pressure for a hydrogen/metal atom ratio (H/M) less than about 0.3 and a slightly higher plateau pressure for H/M greater than about 0.3. This higher pressure corresponds to the reported pressure for palladium hydride. These observations were made for a large surface area palladium powder exposed to both protium and tritium. Helium buildup from tritium decay decreases the lower plateau pressure but does not affect the observations for H/M greater than about 0.3. A multiple-energy hydrogen site occupancy model is proposed to explain qualitatively both the dual plateau and the helium effect in palladium hydride.

Helium from tritium decay causes the desorption isotherm plateau pressure for LaNi4.25Al0.75 tritide to be lowered. From the shape of the 3He altered isotherm, it appears that the material becomes disordered and possibly disproportioned. The microstructure of the parent LaNi4.25Al0.75 tritide material is believed to influence the behavior of 3He from tritium decay.

Intermetallic compounds which react with hydrogen isotopes to form reversible hydrides offer several advantages for storing and processing tritium. Advantages include safe, low pressure, high density storage, and delivery of high purity 3He-free tritium without the use of pumps. As part of a program to devleop metal hydride technology for storing and processing tritium, the effects of tritium aging on the thermodynamic behavior of the tritides are under investigation. During aging of LaNi4.25Al0.75 tritides, the 3He decay product of tritium produced in the lattice does not leave the lattice but causes changes in the thermodynamics of the gas-solid system. Among the changes noted are (1) decreased tritium desorption pressures, (2) increased slopes of desorption isotherm plateaux and (3) small quantities of irreversibly-held tritium. Absorption-desorption cycling and brief heating of samples to 350°C while loaded with deuterium partially reverses these effects. While the desorption isotherms of tribium-aged LaNi4.25Al0.75 tritides resemble the desorption isotherms of amorphous hydrogen storage materials, X-ray diffraction patterns of tritium-aged samples after desorption of tritium do not exhibit the characteristics of an amorphous material. The diffraction patterns show broadening and anisotropic effects that suggest the presence of lattice strains and orientational effects of 3He in the LaNi4.25Al0.75 lattice. Self-interstitials, dislocations and bubbles are probably present in the aged samples.

Helium dynamics in La-Ni-Al tritides have been observed by measuring the plateau pressure decrease for the pressure of tritium in equilibrium with the solid as a function of helium composition. Calculations suggest that a crystal lattice volume expansion, caused by helium, stabilizes the tritide. Temperature cycling the helium-altered, tritium-saturated intermetallic partially restores the plateau pressure. These data are discussed in the context of immobile helium which can gain mobility as the tritide ages.

The Tokamak Fusion Test Reactor (TFTR) at Princeton will start its D-T experiments in late 1993, introducing and operating the tokamak with tritium in order to begin the study of burning plasma physics in D-T. Trace tritium injection experiments, using small amounts of tritium will begin in the fall of 1993. In preparation for these experiments, a series of tests with low concentrations of tritium in deuterium have been performed as an initial qualification of the tritium systems. These tests began in April 1993. This paper describes the initial testing of the equipment in the TFTR tritium facility.

A tritium monitoring system for measuring tritium in low humidity (DTO) nitrogen gas has been developed. Heated ion chambers (at 393 K) measure the amount of tritium that is deposited directly from the waste processing system onto process disposable molecular sieve bed (DMSB) shipping containers at TFTR. For process flow rates up to 1415 L min/sup -1/(50 SCFM) and water vapor compositions up to 5000 ppm/sub v/, tritium activity up to 27 Ci/m/sup 3/ has been measured. Preliminary data from over 20 batch processes are presented.

The Plasma Exhaust Tank (PET) allows TFTR neutral beam regeneration gas to be collected separate from the total TFTR exhaust thereby minimizing the impurities (i.e. oxygen, sulfur hexaflouride). The PET then forwards this gas to the Tritium Purification System (TPS). The PET is capable of holding a minimum of 2 normal neutral beam regenerations (200 std. liters each) with a nitrogen backfill (400 std. liters). Since this volume is slightly less than the volume for 4 neutral beam regenerations without backfill, the tank is sized for the latter case (/spl sim/980 std. liters). The PET pump provides a feed of 2 liters per minute to the TPS with a pressure range of 750 Torr to 200 Torr. At 2 liters per minute and 200 Torr at the discharge of the PET pump the tank can reach a final pressure of 70 Torr. When the TPS output does not meet the requirements for tritium purity, the PET is capable of receiving inferior grade tritium gas back from the TSDS for reprocessing.

Pulse radiolysis experiments using conductivity, polarographic and uv-visible absorption detection techniques have been carried out on the reaction of hydroxyl radical with bis(ethylenediamine)platinum(II)perchlorate in aqueous media. This reaction is shown to proceed by OH addition to the platinum center to yield a nascent product where the metal is in a formal oxidation state of III. The subsequent behavior of this Pt(III) transient generates three additional transients, whose formations are dependent upon the pH and presence of free chloride ion. A mechanism is proposed whereby these transients are interrelated through acid-base, chloride substitution, and water elimination processes. Evidence is presented to support the classification of the Pt(III) species into two groups having the compositions of Pt(en)/sub 2/(X)/sup n+/ (X = OH, H/sub 2/O, Cl; n = 2,3) and Pt(en)(en-H)/sup 2 +/ (en-H = /sup -/NHCH/sub 2/CH/sub 2/NH/sub 2/). For the former group, the respective wavelength maxima and molar absorption coefficients are 270 nm, ca. 4500 M/sup -1/ cm/sup -1/ (X = OH), < 250 nm (X = H/sub 2/O), and 260 nm, 8000 M/sup -1/ cm/sup -1/ (X = Cl). For Pt(en)(en-H)/sup 2 +/, two absorption bands are found with peaks at 340 nm (2900 M/sup -1/ cm/sup -1/) and 480more » nm (1500 M/sup -1/ cm/sup -1/). This latter species is also the major product of the reaction of the hydrated electron and trans-di-hydroxobis(ethylenediamine) platinum(IV) perchlorate which was investigated by absorption and conductivity techniques. The possible structures of these intermediates are discussed.« less

The Re(CO)/sub 5/ radical has been generated in the pulse radiolysis of a variety of organorhenium compounds in ethanol solution as well as in the flash photolysis of Re/sub 2/(CO)/sub 10/ in isoctane solution. This radical exhibits an optical absorption band in the visible region with a maximum at 535 nm and a molar extinction coefficient, in ethanol, of epsilon/sub 535/ 1000 +- 100 M/sup -1/ cm/sup -1/. Absolute rate constants were determined for the reactions of the solvated electron, in ethanol, with Re(CO)/sub 5/Br (6.7 x 10/sup 9/), Re(CO)/sub 5/SO/sub 2/CH/sub 3/ (6.6 x 10/sup 9/), and Re/sub 2/(CO)/sub 10/ (7.8 x 10/sup 9/ M/sup -1/ s/sup -1/). Rate constants were also obtained for the reactions of Re(CO)/sub 5/ and of Mn(CO)/sub 5/ in abstracting a chlorine atom from carbon tetrachloride in ethanol solution. The values, at 22/sup 0/C, are 3.9 x 10/sup 7/ and 6.1 x 10/sup 5/ M/sup -1/ s/sup -1/, respectively, indicating a 65-fold higher reactivity for the pentacarbonylrhenium radical as compared with the pentacarbonylmanganese radical in this abstraction reaction. The rate constant for the recombination reaction of Re(CO)/sub 5/ radicals in isooctane was found to be 2k/sub 7/ = 5.4 x 10/sup 9/ M/sup -1/more » s/sup -1/.« less

The absorption spectrum of PuF 6 is investigated using a long-pass multiple reflection cell. Cross sections over the spectral region of 3000–9000 A are reported. Due to the enhanced sensitivity of our apparatus the wavelengths and absorption cross sections are significantly improved over the previously available data.

Dimensional co-ordination is a convention limiting the number of sizes to which building components are made for general use. Its importance increases with the industrialization of building methods, and with the extent to which building technology moves towards the interchangeability of factory-made components. Conflicting proposals are beginning to be resolved, and preferred dimensions are being tested in practice. The possibility of a change to the metric system is relevant.

The Tokamak Fusion Test Reactor (TFTR) is a large tokamak which has performed experiments with 50:50 deuterium - tritium fuelled plasmas. Since 1993, TFTR has produced about 1090 D - T plasmas using about 100 grams of tritium and producing about 1.6 GJ of D - T fusion energy. These plasmas have significant populations of 3.5 MeV alphas (the charged D - T fusion product). TFTR research has focused on alpha particle confinement, alpha driven modes, and alpha heating studies. Maximum D - T fusion power production has aided these studies, requiring simultaneously operation at high input heating power and large energy confinement time (to produce the highest temperature and density), while maintaining low impurity content. The principal limitation to the TFTR fusion power production was the disruptive stability limit. Secondary limitations were the confinement time, and limiter power handling capability.