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A small liquid fluoride salt test apparatus has been constructed and testing has been conducted to examine the compatibility of silicon carbide (SiC), Inconel 600 and a spiral wound gasket material in FLiNaK, the ternary eutectic alkaline metal fluoride salt mixture. These tests were conducted to evaluate materials and sealing systems that could be used in fluoride salt systems. Three months of testing at 700 °C was conducted to assure that these materials and seals would be acceptable when operating under prototypic operating conditions. The SiC specimens showed little or no change over the test period, while the spiral wound gasket material did not show any degradation except that salt might have been seeping into the outermost spirals of the gasket. The Inconel 600 specimens showed regions of voiding which penetrated the specimen surface to about 250 μm in depth. Analysis indicated that the salt had leached chrome from the Inconel surface, as was expected for this material.

A liquid fluoride salt experiment has been constructed and used to acquire natural convection heat transfer data. The experiment used FLiNaK salt in a small cell that included a cylindrical electrical heater, 1.27 cm in diameter, oriented vertically in a FLiNaK bath. Thermocouples internal to the heater were used, along with FLiNaK temperature measurements and heater power measurements, to determine natural circulation heat transfer coefficients. These data were acquired for Rayleigh numbers ranging from 3 × 105 to 8 × 109 and salt temperatures from 560 °C to 640 °C. Test results show that measured heat transfer coefficients are consistent with conventional natural convection heat transfer coefficients for cylinders, but the average error can be as high as 20% using these correlations. Correlations developed by fitting the data for this experiment show much lower errors (

Up to four irradiation tensile creep tests are planned for the target region of the high flux isotope reactor on two graphite grades: PCEA and NBG-18. The initial experiment is designed for an irradiation temperature of 600 °C and at fluences between 1 × 1022 n/cm2 and 1.4 × 1022 n/cm2 (E > 50 keV).

Two irradiation capsules have been designed for the target region of the high flux isotope reactor (HFIR). The objective is to provide dimensional change and physical property data for four candidate next generation nuclear plant (NGNP) graphites. The capsules will reach peak doses of ∼1.59 and ∼4.76 dpa, respectively, at temperatures of 900, 1200, and 1500 °C.

A small molten fluoride salt experiment has been constructed and tested to develop experimental techniques for application in liquid fluoride salt systems. There were five major objectives in developing this test apparatus: Allow visual observation of the salt during testing (how can lighting be introduced, how can pictures be taken, what can be seen) Determine if IR photography can be used to examine components submerged in the salt Determine if the experimental configuration provides salt velocity sufficient for collection of corrosion data for future experimentation Determine if a laser Doppler velocimeter can be used to quantify salt velocities. Acquire natural circulation heat transfer data in fluoride salt at temperatures up to 700oC All of these objectives were successfully achieved during testing with the exception of the fourth: acquiring velocity data using the laser Doppler velocimeter. This paper describes the experiment and experimental techniques used, and presents data taken during natural circulation testing.

The Charpy impact response of reirradiated Heavy-Section Steel Irradiation (HSSI) Program Weld 73W has been determined at three fluence levels. The Charpy specimens had previously been irradiated at 288 C to 1.8 x 10{sup 19} cm{sup -2} (E > 1 MeV) and annealed at 454 C for 168 h. The results show that the change in the 41-J Charpy energy level transition temperature (OTT{sub 41-J}) of the reirradiated specimens is slightly higher than predicted by the vertical shift method, but significantly less than predicted by the lateral shift method. Previous results have also shown that the upper-shelf energy (USE) over-recovers as a consequence of annealing, which may explain why the USE value after a significant amount of reirradiation is approximately equal to the USE value in the unirradiated condition.

The TRIST-ERI capsule was assembled and irradiated in a large Removable Beryllium (RB{star}) position of the High Flux Isotope Reactor (HFIR) during this reporting period. Irradiation began on March 8, 1996, was completed on June 20, 1996, during operating cycles 344, 345, and 346. This report describes the thermal operation of the capsule.

A collaborative DOE/Monbusho series of irradiation experiments is being implemented to determine, in situ, the effects of irradiation on the electrical resistivity of ceramic materials. The first experiment, TRIST-ER1, has been designed to irradiate 15 Al{sub 2}O{sub 3} test specimens at 450{degrees}C in an RB position of the High Flux Isotope Reactor (HFIR). Each test specimen is located in a sealed vanadium subcapsule with instrumentation provided to each subcapsule to measure temperature and resistance, and to place a biasing voltage across the specimen. Twelve of the specimens will be biased with 200 V/mm across the sample at all times, while three will not be biased, but can be if so desired during the irradiation. The experiment design, component fabrication, and subcapsule assembly have been completed. A three cycle irradiation, to a fast neutron (E>0.1 MeV) fluence of about 3x10{sup 25}n/m{sup 2} ({approx}3 dpa in Al{sub 2}O{sub 3}), is expected to begin early in March 1996.

Design of four spectrally tailored capsules to irradiate magnetic fusion energy (MFE) materials specimens in the new High Flux Isotope Reactor (HFIR) removable beryllium (RB∗) facility at temperatures of 60, 200, 330 and 400°C, is described. These designs incorporate provisions for removal, examination and reencapsulation of the specimens at intermediate exposure levels en route to a target exposure level of 30 displacements per atom (dpa). With the exception of the 60°C capsule, where the test specimens are in direct contact with the reactor cooling water, the specimen temperatures (monitored by 21 thermocouples) are controlled by varying the thermal conductance of a small gap region between the specimen holder and the containment tube. Hafnium shields are used to tailor the neutron spectrum to closely match the helium production-to-atom displacement ratio (14 appmdpa) expected in an austenitic stainless steel fusion reactor first wall. These MFE capsule irradiations will begin in early 1988.