P E R I O D ENDING SEPTEMBER IO, 7954 T w o UF3-bearing capsules and two UF4-bearing capsules i n t h i s series w i l l be irradiated for s i x weeks each t o amplify the apparent differences i n the effects of UF, and UF, on Inconel. It is interesting to note that the UF, capsule i n t h i s series i s the f i r s t one run i n the MTR and the f i r s t one run a t 800 w/cm3 or greater that has not shown a tendency toward intergranular corrosion. Whether the difference between earlier UFq-bearing capsules and the one i n t h i s series i s due t o improved temperature control or t o uranium concentration effects w i l l be determined by additional irradiations. FlSSlON P R O D U C T C O R R O S I O N
C. C.
STUDY
G. W. K e i l h o l t z Webster Solid State D i v i s i o n
Steps are being taken t o perform corrosion tests out-of-pile w i t h irradiated fuel in order t o separately study the effects on lnconel of fission-product concentration and of lnconel irradiation. A water-cooled f a c i l i t y for irradiation of s o l i d fuel was constructed and has been installed in position C-46 of the LITR. T h e unperturbed thermal f l u x i s on the order of 4 x l o T 3 .An lnconel tube has been constructed for casting solid bars of f u e l 1 in. long and 0.1 in. i n diameter. The s o l i d bars of fuel w i l l be transferred t o lnconel capsules for irradiation. T h e capsule has been constructed s o that it can be welded shut without the bars being melted and can be reopened i n the hot c e l l for transfer of the fuel t o the corrosion t e s t capsule. Upon completion of an out-of-pile heating cycle, the t e s t capsule w i l l be opened in the hot cell. T h e fuel w i l l be d r i l l e d out and divided into three samples: a portion for petrographic study t o detect any oxidation or reduction, a portion for mass spectrographic study t o determine burnup, and a portion for chemical analysis of the fuel. T h e capsule w i l l be s l i t on the remote s l i t t i n g machine described below for a metallographic study. At least two concentric samples can be taken from a capsule of t h i s s i z e by remote means. F A C I L I T I E S FOR HANDLING IRRADIATED CAPSULES
C. C.
G. W. K e i l h o l t z Webster Solid State D i v i s i o n
It was observed metaIIograpliicaIly, i n some cases, that when several transverse sections were taken from a single fluoride fuel corrosion
capsule the corrosion pattern was not consistent over the length of the capsule but appeared t o be a function of the longitudinal temperature gradient. One method of obtaining a longitudinal section would be t o grind away half of the capsule on the m i l l i n g machine. However, by such a method it would be d i f f i c u l t t o ascertain that a section through the diameter of the capsule had been made. Also, the m i l l i n g operation would create a serious contamination problem. The method being used consists i n passing the capsule longitudinally by a 10-mil-thick s i l i c o n carbide fine-grit wheel and thus s l i t t i n g the capsule down the center. T h e capsule i s clamped i n t o a v i s e and then fed into the wheel by means of a mechanical linkage which i s to be replaced by a variable-speed motor and a contact cutoff switch. When the capsule i s put into the gripping adapter in the vise, it i s automatically aligned so that the wheel w i l l c u t i n the plane of a diameter through the capsule. B y making different gripping adapters, various sizes of tube can be s l i t lengthwise. Thus far the apparatus has been used on only MTR-type fluoride fuel capsules (O.lOO-in.-ID and 0.200-in.OD); it has worked very satisfactorily. Since the abrasive wheel has a rubber base, it must be kept cool. The area around the cut m u s t a l s o be kept cool to prevent any high thermal sfresses from affecting the corrosion results. The wheel and specimen are over a tray and are covered w i t h a splash shield s o that a l i q u i d coolant can be used. The coolant level i s always kept above the bottom edge of the abrasive wheel so that by cutting upward into the specimen the coolant i s carried i n t o the cut; therefore the specimen need not be i n the coolant. Carbon tetrachloride i s used as the coolant because i t does not react w i t h the fluoride fuel a t high temperatures. It i s forced i n t o the tray from outside the hot c e l l through Tygon tubing by air pressure, T h e tray and splash shield are attached t o the mount far the v i s e and they move w i t h the specimen. Once installed w i t h i n the hot cell, the remotely operated tube-slitting machine can be used w i t h ease i n cutting longitudinal sections from various sizes of tubing. Thicker abrasive wheels can be used for heavier walled twbing. The advantages of t h i s method of cutting are that it permits visual observation of the amount of fuel l e f t on the tube walls, i t permits observation of constrictions without the necessity of removing or disturbing the
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