Thomas F. Lin

Magnetohydrodynamically enhanced heat transfer in a liquid metal system

Abstract The phenomena of liquid metal flow under the influence of magnetic and electric fields are important in the development and design of nuclear and metallurgical plants, such as the blanket cooling systems of fusion or fast breeder reactors and electromagnetic stirring devices. In this study, a computer code that models recirculating flows in two dimensions using a k − ϵ turbulence model is expanded to include the magnetohydrodynamic (MHD) effects of applied electric and magnetic fields. This modified code is then used to examine the effect of MHD stirring on the heat transfer characteristics of a liquid metal cooling system. Using liquid sodium properties, various thermophysical properties are investigated. The results indicate that a significant increase in the rate of heat transfer is obtainable when the heat transfer system is operated in the presence of MHD stirring.

Considerations Of Sea Water Conductivity Enhancement For Electromagnetic Thrusters

This paper discusses the mechanisms of enhancing the electric conductivity of sea water. The direct impact of conductivity enhancement of sea water is the improvement of propulsion performances of marine vehicles that use the magnetohydrodynamic (MHD) thrusts of sea water. The performance improvement can be in energy efficiency or in vehicle speed. Injection of strong electrolytes (acids or bases) into the main sea water flow in the MHD channel appeared to be the most logical wag of achieving the purpose. Several seedin compoun s were compared from the electrochemical points of view. The advantage of using concentrated sulfuric acid (H/sub 2/SO/sub 4/) over the others was conclusively discussed. It was found that the computed conductivity of a synthetic sea water of known salt constituency is consistent with the average conductivity of ocean water. Parametric studies of volumetric mixing ratios and seeding electrolytes were also conducted, and their effects on the conductivity of the mixed sea water were compared and discussed.

Horizontal annular flow measurements using pulsed photon activation and film thickness distribution modelling

Abstract The Pulsed Photon Activation (PPA) technique for the non-intrusive measurements of single and two-phase flows in a horizontal pipe was developed. The advantages of PPA over pulsed neutron activation (PNA) are discussed. Fluid velocity determinations using such a technique were carried out. An interesting subregion of the horizontal annular flow regime was found to have twin-peak PPA activation time profiles. These twin peaks were confirmed to be associated with the film flows on the upper and lower parts of the horizontal pipe, using the directionality of the PPA bremsstrahlung tagging beam. Film thickness measurements around the circumference of horizontal annular flows were also carried out using a resistivity needle probe and analytical models involving droplet exchange and secondary vapor flow pattern were compared with the experimental data.

Two-Phase Flow Measurements Using a Pulsed-Photon-Activation (PPA) Technique

Radiation-induced tagging techniques have been useful for the non-intrusive measurement of two-phase flow parameters such as mass-weighted velocity and void fraction. Pulsed-Neutron-Activation (PNA) measurements in water systems, which use the 160(n,p)16N reaction to produce a 7.1 s half-life 16N gamma tag, have been reported by Kehler [1,2] and Perez-Griffo, et al.[3,4] Using the LINAC at Rensselaer Polytechnic Institute’s (RPI) Gaerttner Laboratory, it was recently observed that in addition to the 160(n,p)16N reaction, there is a more intense 160(γ,n)150 reaction which produces a 122 s half-life positron emitter (150) with a gamma threshold energy of 15.7 MeV. As shown in Figure 1, the cross section of this reaction shows a broad resonance near the gamma energy 22–24 MeV.[5] The annihilation radiation from 150 positron decay results in a tagging signal over an orderof-magnitude more intense than that obtained from 16N. This paper describes the special features of this more intense 150 tag, and where it can make a contribution in two-phase flow research. Results of recent two-phase flow measurements using PPA are presented. The results of simultaneous film thickness measurements in some annular two-phase flows using a needle probe are also presented.

Thermal Cooling Limits of Sbotaged Spent Fuel Pools

To develop the understanding and predictive measures of the post “loss of water inventory” hazardous conditions as a result of the natural and/or terrorist acts to the spent fuel pool of a nuclear plant. This includes the thermal cooling limits to the spent fuel assembly (before the onset of the zircaloy ignition and combustion), and the ignition, combustion, and the subsequent propagation of zircaloy fire from one fuel assembly to others

Capillary-Pumped Passive Reactor Concept for Space Nuclear Power

To develop the passively-cooled space reactor concept using the capillary-induced lithium flow, since molten lithium possesses a very favorable surface tension characteristic. In space where the gravitational field is minimal, the gravity-assisted natural convection cooling is not effective nor an option for reactor heat removal, the capillary induced cooling becomes an attractive means of providing reactor cooling.

Measurement of flow in a horizontal pipe using the pulsed photon activation technique

The pulsed photon activation (PPA) technique for nonintrusive measurements of singleand two-phase flows in a horizontal pipe is developed. The advantages of PPA over pulsed neutron activation are discussed. Fluid velocity determinations using such a technique are carried out. An interesting subregion of the horizontal annular flow regime is found to have twin peak PPA time profiles. It is confirmed that these twin peaks are associated with the film flows on the upper and lower parts of the horizontal pipe, using the directionality of the PPA bremsstrahlung tagging beam. Fil thickness measurements around the circumference of horizontal annular flows are also carried out using a resistivity needle probe, and analytical models involving droplet exchange and secondary vapor flow pattern are compared with the experimental data.