Test work was completed on development of a stripping method for the amine extraction (Amex) process which produces a concentrated uranyl nitrate solution for shipment to the refinery. This procedure offers potential cost savings by simplifying the overall mill-refinery flowsheet. The process involves treatment of the amine extract with calcium nitrate solution to convert the uranium in the solvent to a nitrate complex, stripping the uranium with water or dilute nitric acid, and recovery of nitrate from the solvent for recycle by contact with a lime slurry.

Further calculations have been made to determine the desired radial fuel distribution in the HFIR and in the forthcoming HFIR critical experiment. In the process the design of the core was changed to include a 1-cm-thick annular space of water between the two nearly equally thick fuel annuli, a metal-to-water ratio in the fuel annuli of 1.0 (0.050 in. thick plates and coolant channels ) was specified, and the active length of the core was increased from 18 to 20 in. Results of the calculations indicated that the largest ratio of maximum meat thickness to minimum meat thickness occurred in the inner fuel annulus and was equal to 3.6, while the maximum fuel concentration occurred in the outer fuel annulus and was equivalent to about 0.7 g of U-235/cm^3 of meat. The total U-235 loading for this core was 8.01 kg, which results in a core lifetime of about 14 days.

Results of the examinations of corrosion specimens exposed in the HRT are presented. Specimens examined included (1) core screen samples, (2) core specimen array No. 1, (3) blanket specimen array No. 2, (4) core solution line specimen arrays No. 103 and 103A, (5) blanket solution line specimen array No. 203. Complete information is still not available on all the specimens removed from the reactor, however, those data which have been accumulated are presented. These include corrosion rates, computed from specimen weight-changes, and results of chemical analyses of scales removed from the specimens or specimen holders. Also included in the report is a summary of the HRT operating schedule during exposure of the specimen and of the status of examinations for those specimens removed from the reactor prior to run 20.

A total of 104 thermal cycles between 250°F and 1350°F were imposed on a 3 1/2-in. and a 4-in. freeze flange to determine their susceptibility to thermal fatigue. The flange clamping arrangement was modified and various gaskets were used during the cycling in an effort to reduce the gas leakage problem.

A proposed modification to the experiment off-gas system for the EGCR-LITR Capsule Experiment is evaluated by comparing the atmospheric radiation doses to laboratory personnel that could result in the event of an experiment failure while utilizing the present off-gas system to those doses that would result if various modifications to the existing system were effected. The modifications considered include the addition of an iodine vapor adsorber and a krypton-xenon adsorber. The addition of an iodine vapor adsorber to the off-gas system, which presently includes an absolute filter, reduces the atmospheric dose to the thyroid from 510 mr to 1.4mr. The total body dose is also reduced from 2.2 to 1.3 mr. The total body dose can be further reduced to 0.7 mr if a large krypton-xenon adsorber is included. Basd upon these calculated atmospheric radiation doses it is concluded that the addition of an activated charcoal iodine vapor adsorber will reduce the atmospheric hazard to an acceptable level.