Abstract: A generalized equation of state developed by Gouq-Jen Su and Chien-Hou Chang is used for predicting P-V-T behavior of BF3 at high gas densities.

Abstract: An experimental study of valve stem freeze seals was undertaken as part of the effort to develop components for high temperature service in advanced sodium-cooled reactor systems.

One of the uncertainties concerning the use of uranium-10 wt.% molybdenum in the ORNL Fast Burst Reactor is the thermal-cycling behavior of this alloy. Accordingly, an experimental program was undertaken to determine whether transformation or distortion of gamma-phase uranium--10 wt.% molybdenum can occur during simulated fast-burstreactor thermal cycling, and, should transformation occur, to establish the thermal cycling behavior of partially transformed uranium- - 10 wt.% molybdenum. Specimens were prepared by vacuum casting pins in coated- graphite molds, homogenizing the castings at 1650 deg F for 24 hr, and centerless grinding and cutting to 0.158-in. diameter by 1.5 in. long. The pins were sealed in evacuated Vycor tubes, heated rapidly both above and below the gamma- transformation temperature. and then cooled slowly to simulate reactor thermal cycling. Measurements of the time required to initiate transformation by conventional isothermal methods were employed to insure that the alloy material behaved as indicated in the literature. Observation of changes in appearance, dimensions, density, resistivity, and metallographic structure were used to obtain the desired information. It was found that thermal cycling did not cause growth or distortion of either gamma-phase or partially transformed uranium-- 10 wt.% molybdenum pins. Transformation of gamma phase to alpha + …

Valve stem freeze seals for high-temperature service in advanced sodium- cooled reactor systems were studied. An experimental model, suitable for use with a 6-in. size valve, operated satisfactorily under a variety of conditions. The freeze seal region was cooled by natural convection to ambient atmosphere; cooling by both circumferential and longitudinal finned sections was experimentally studied. The operating conditions included sodium bulk temperatures up to 1300 tained F, sodium pressures up to 75 psig, and ambient temperatures as high as 150 tained F. Anticonvection rings were pcsitioned in the sodium-filled annulus between stem and stemguide, and the effects of their presence was studied. Predictions of temperature profiles along the stem, using several different analytical methods, were compared with experimental results. (auth)