[en] The development of a Dewar system for handling liquid helium under weightless conditions is described. Porous plug designs for the prevention of superfluid creep out of the dewar through the vent line were evaluated. For the purpose of designing a neck to provide a transition from the cold cavity to the outside, the loads carried by the neck and equipment supports were studied. Temperature, pressure, and mass flow instrumentation for monitoring Dewar performance were also evaluated. In addition, multilayer blankets consisting of aluminized Mylar separated by Dacron net sheets were designed to insulate the pressure vessel. The dewar system is suggested for use with the star tracking telescope aboard the relativity satellite

No abstract available

[en] This report describes results of a parametric study of quantities of radioactive materials that might be discharged by a tornado-generated depressurization on contaminated process cells within the presently inoperative Nuclear Fuel Services' (NFS) fuel reprocessing facility near West Valley, New York. The study involved the following tasks: determining approximate quantities of radioactive materials in the cells and characterizing particle-size distribution; estimating the degree of mass reentrainment from particle-size distribution and from air speed data presented in Part 1; and estimating the quantities of radioactive material (source term) released from the cells to the atmosphere. The study has shown that improperly sealed manipulator ports in the Process Mechanical Cell (PMC) present the most likely pathway for release of substantial quantities of radioactive material in the atmosphere under tornado accident conditions at the facility

[en] A model is presented to describe the time-dependent flow and retention of stable iodine isotopes and the decay of ¹³¹I in a nuclear fuel reprocessing plant. The plant consists of 16 units of equipment such as a voloxidizer or graphite burner, fuel dissolver, solvent extractors, storage tanks, vaporizers, primary iodine sorbers, and silver zeolite. The rate of accumulation of bulk and radioactive iodine in these units and in the environment is described using 19 differential equations. Reasonable time-dependence of iodine retention factors (RFs) by the plant were calculated. RFs for a new plant in excess of 10⁶ for stable iodine and ¹²⁹I decrease to the range of 10³ to 10² as plant operating times exceed 50 to 100 days. The RFs for ¹³¹I also decrease initially, for a period of approximately 10 days, but then increase by several orders of magnitude due to radioactive decay and isotopic exchange. Generally, the RFs for ¹³¹I exceed those for stable iodine by factors of 10⁴ or more. 19 references, 13 figures, 2 tables

[en] It is shown that there are appropriate data for calculating the distributions of many potential impurities between liquid and vapor phases in which UF₆ is the principal component, at least in the liquid phase. Such calculations are presented for nine chemicals assumed to be present in the vapor phases at concentrations of 1 and 2 mole %

[en] The radioactive nuclide ¹⁴C is formed in all nuclear reactors due to absorption of neutrons by carbon, nitrogen, or oxygen. These may be present as components of the fuel, moderator, or structural hardware, or they may be present as impurities. Most of the ¹⁴C formed in the fuels or in the graphite of HTGRs will be converted to a gaseous form at the fuel reprocessing plant, primarily as carbon dioxide; this will be released to the environment unless special equipment is installed to collect it and convert it to a solid for essentially permanent storage. If the ¹⁴C is released as carbon dioxide or in any other chemical form, it will enter the biosphere, be inhaled or ingested as food by nearly all living organisms including man, and will thus contribute to the radiation burden of these organisms. Detailed estimates are presented of the amounts of ¹⁴C formed in LWRs, HTGR, and LMFBR with emphasis on those pathways that are likely to lead to the release of this nuclide, either at the reactor site or at the fuel reprocessing plant. 83 references

[en] A cost-benefit analysis and an analysis of the reduction in population dose from the use of different decontamination equipment in the off-gas system of a model plant for processing spent fuel from HTGR type reactors are presented

No abstract available

[en] This report describes a reanalysis of data on liquid-liquid and liquid-vapor equilibria in the system UF₆-HF, and the associated vapor pressures, and the applicability of these data to the use of analyses of vapor-phase samples for determining liquid-phase compositions; that is, determining the UF₆ content of the solution. Such use of vapor-phase sampling requires that: (1) UF₆ and HF be the only significant components present; (2) equilibrium between liquid and vapor phases exists during the sampling operation. The first specification does not mean the exclusion of tens of parts per million of nonvolatile corrosion products; instead, it refers to the absence of appreciable quantities of species in liquid and vapor phases that could change the equilibrium distribution of UF₆ and HF between these two phases. The present specification of liquid solution requires that the materials' temperature be above 61.2⁰C

[en] Currently, liquid-phase samples from uranium hexafluoride (UF₆) cylinders are used at all US DOE ²³⁵U enrichment facilities to determine the chemical content of cylinders - a requisite in the control and accountability of nuclear materials. Previously published reports note the economic incentives to use vapor-phase sampling for volatile impurities (as a partial replacement for liquid-phase sampling) if the liquid-phase composition can be determined from analysis of vapor-phase samples by using a model of vapor-liquid equilibrium between UF₆ and its common impurities. Such a model was adapted for this purpose in earlier work. Hydrogen fluoride, a common impurity, in UF₆ was shown not to conform to the model although other methods for calculating its concentration in the liquid phase from vapor-phase analyses were presented. This report describes preliminary comparisons with experimental data of model calculations of concentrations of nitrogen, oxygen, fluorine, chlorine trifluoride, and silicon tetrafluoride in liquid UF₆ based on analyses of the vapor phases. 4 figs., 13 tabs