G.A. Greene

Total hemispherical emissivity of oxidized Inconel 718 in the temperature range 300–1000°C ☆

Total hemispherical emissivities were measured for Inconel 718 as a function of sample temperature. Measurements were made for both unoxidized and oxidized samples. The oxidation temperatures were 1000°C, 1100°C and 1142°C and the oxidation times were 15, 30 and 60 min, respectively. The oxidized samples showed a significant increase in emissivity over the unoxidized one which was in an as-received condition. No apparent pattern was observed in the change of emissivity as a function of oxidation time at a given oxidation temperature. In some cases, emissivity measurements made with increasing temperature were greater than those made with descending temperature. One possible explanation for this is the spalling of the oxide layer as the sample area contracted with descending sample temperature.

Target studies with BNL E951 at the AGS

We report initial results of exposing low-Z solid and high-Z liquid targets to 150-ns, 4/spl times/10/sup 12/ proton pulses with spot sizes on the order of 1 to 2 mm. The energy deposition density approached 100 J/g. Diagnostics included fiberoptic strain sensors on the solid target and high-speed photography of the liquid targets. This work is part of the R&D program of the Neutrino Factory and Muon Collider Collaboration.

Second Generation HTS Quadrupole for FRIB

Quadrupoles in the fragment separator region of the Facility for Rare Isotope Beams (FRIB) will be subjected to very large heat loads (over 200 Watts) and an intense level of radiation (~10 MGy per year) into the coils of just the first magnet. Magnets made with High Temperature Superconductors (HTS) are advantageous over conventional superconducting magnets since they can remove these heat loads more efficiently at higher temperatures. The proposed design is based on second generation (2G) HTS which allows operation at ~50 K. 2G has been found to be highly radiation tolerant. The latest test results are summarized. The goal of this R&D program is to evaluate the viability of HTS in a real machine with magnets in a challenging environment where HTS offers a unique solution.

Activation of natural Hf and Ta in relation to the production of 177Lu.

The isotope (177)Lu is used in nuclear medicine and biology for in vivo applications as a radioactive label of various targeting agents. To extend the availability of no-carrier added (177)Lu, we investigated the feasibility of its production in a proton accelerator. Tantalum and Hf targets were irradiated and chemically processed to determine the radioisotope yield and cross-sections. The largest cross-sections (approximately 20 mb) were found for the Hf target at 195 MeV; however, the presence of co-produced Lu isotopes may limit the product applications. The results are in good agreement with theoretical data calculated using computer codes MCNPX and ORIGEN2S. Production of relevant medical isotopes such as (167)Tm and (169)Yb from the above targets is discussed as well.

A new technique for measuring the Fickian diffusion coefficient in binary liquid solutions

The present study details the development of a new technique for measuring the Fickian diffusion coefficient in binary liquid solutions, and reports the coefficients obtained using this new technique for two electrolytic systems. The new method, called the decaying pulse technique, takes advantage of the behavior of a semi-infinite system exposed to a transient concentration pulse. The method permits simple, direct, and absolute determination of the diffusion coefficient, and requires measurement of only time and distance. It is applicable to many different types of fluid pairs, and requires no knowledge of solution properties. The decaying pulse technique was used to measure the average diffusion coefficient of potassium chloride in water and sodium chloride in water, at 18.5, 25.0, and 30.0°C. The current experimental results were compared to those from other published investigations, and were generally found to agree within the predicted uncertainty of the current measurements ±7.6%.

Vaporization of tungsten in flowing steam at high temperatures

Abstract Chemical reactions of tungsten with steam which persist to tungsten temperatures as low as 800°C result in the formation of a hydrated tungsten-oxide which has a high vapor pressure and is readily convected in a flowing atmosphere. The vaporization reaction removes the oxide scale that forms on the tungsten surface as it forms, leaving behind a fresh metallic surface for further oxidation and vaporization. Experiments were conducted with cylindrical tungsten rods heated to temperatures from approximately 700°C to 1350°C in flowing steam which was superheated to 140°C to measure the oxidative vaporization rates of tungsten in steam. The results of these experiments revealed a threshold temperature for tungsten vaporization in steam between 700°C and 800°C. Other tests were conducted over the temperature range of 800–1350°C. In these tests, the tungsten rods were found to have lost weight due to vaporization of the tungsten and the missing weight was collected in the downstream condensate system. The aerosol formed a fine white smoke of tungsten-oxide which was visible to the eye as it condensed in the laminar boundary layer of steam which flowed along the surface of the rod. The aerosol continued to flow as a smoke tube downstream of the rod, flowing coaxially along the centerline axis of the quartz glass tube and depositing by impaction along the outside of a bend and at sudden area contractions in the piping. The vaporization rate data from 17 experiments which exceeded the vaporization threshold temperature are presented. Two correlations to the present data are presented and compared to a published correlation in the literature [7] .

Total cross sections for the production of 22Na and 24Na in proton-induced reactions on 27Al from 0.40 to 22.4 GeV

Total cross sections for production of 22 Na and 24 Na from the irradiation of 27 Al by protons with incident energies between 0.40 and 22.4 GeV have been measured. The overall uncertainties for these measurements were less than 3%. The measured values compare well with previous measurements and evaluations. � 2003 Elsevier B.V. All rights reserved.

The Effect of Proton Irradiation on the Critical Current of Commercially Produced YBCO Conductors

Samples of YBCO superconductor from two manufacturers were irradiated with protons at the BLIP facility at BNL. Two specimens of each type of conductor were irradiated to five fluences covering the range from 1016 to 4 times1017 protons/cm2. The beam parameters for the irradiations were 42 muA and 142 MeV. The critical current (zero field, 1 muV/cm) for all twenty samples was measured in liquid nitrogen before and after irradiation to quantify the effects of high-dose proton-induced radiation damage on the performance of the conductor, and thus evaluate its suitability for service in high-radiation environments. All of the specimens had a pre-irradiation current of about 100 A. This current decreased linearly with fluence, with a slope of about 20% per 1017 protons/cm2. The agreement between the two samples of each brand of conductor was exceptional.

An R&D program for targetry and capture at a neutrino factory and muon collider source

The need for intense muon beams for muon colliders and for neutrino factories based on muon storage rings leads to a concept of 1-4 MW proton beams incident on a moving target that is inside a 20-T solenoid magnet, with a mercury jet as a preferred example. Novel technical issues for such a system include disruption of the mercury jet by the proton beam and distortion of the jet on entering the solenoid, as well as more conventional issues of materials lifetime and handling of activated materials in an intense radiation environment. As part of the R&D program of the Neutrino Factory and Muon Collider Collaboration, an R&D eort related to

Heat, mass, and momentum transfer in a multifluid bubbling pool

Publisher Summary This chapter reviews the available literature applicable to heat, mass, and momentum transfer in multifluid bubbling pools. It discusses a series of seven separate experimental investigations conducted to develop a comprehensive set of models for incorporation in the CORCON computer code, which models molten core-concrete interactions. The results of these seven separate investigations along with the mathematical models for each of the processes are also presented. The chapter concludes with a discussion of major uncertainties and areas in need of further investigation and model development. It is observed that the study of bubbling heat transfer to vertical boundaries has an impressive database, covering a range of Prandtl numbers from 2.5 to 7500. Under certain circumstances, the rising bubbles can drive mass transport across the interface. If the rate of mass entrainment can be balanced by the rate of settling of the entrained droplets, the upper layer can become a heterogeneous mixture layer.