Plutonium systems

The techniques used in the work have generally been spectroscopic visible-uv for quantitative determinations of species concentrations and infrared-Raman for structural aspects of the polymer. Although the former has often been used in the study of plutonium systems, there has been considerably less usage made of the latter in the actinide hydrolysis mechanisms. 

After dark-condition equilibrium was established, as indicated by the visible spectra, the photo-shift in equilibrium was observed to be completely reversed when the illumination ceased. This photogalvanic effect maintained a mass balance in the system, with no reagent consumed or generated during the dark-light-dark cycle. This observation suggested that the plutonium system in the proper network of a concentration cell... 

Although PUCI4 has been well characterized in the gas phase (51) in the temperature range 670-1025 K, all attempts to obtain tTiTs compound in the solid state have failed. Use of a plot of the difference AHf(MCl4,c) - AHf(M , aq) (, 8) as a function of the actinide ionic radii ( ) (as done above for PuFa) in the case of thorium, protactinium, uranium and neptunium yields a first path leading to aH (PuC14,c). A second path involves the extrapolation to the plutonium system of the difference AH5o n( C 4 ) ... 

Other less usual combinations of fissile and fertile materials may also be used for nuclear fuels, such as and or Th and Pu. This chapter, however, is concerned only with the plutonium system diagrammed in Fig. 3.1 and the thorium, system... 

Table 11.2 shows the results of an EDA analysis on the neutral ytterbium and plutonium complexes. The total bonding energy is substantially more negative for the plutonium system, even though the sum of the prerelaxation electrostatic and Pauli components is much more favorable in the lanthanide compound. The much larger orbital term in the actinide compound reflects the appreciably larger hybridization of the 5f orbitals with the [Pbjj] cage. 

A series of experiments with hydrogen-moderated plutonium systems has been performed in the Physical Constants Testing Reactor (PCTR). The boron concentration required to reduce the infinite multiplication factor, k , to unity was measured for various Pu-240 concentrations, fuel plate thicknesses, and moderator-to-fuel ratios. The measured values of the boron concentra-Uon were compared to theoretical predictions to check the accural of calculational methods and parameters. The principal components for these experiments were Pu-Al (M wt% Pu), pure polyethylene, and borated lyetlqrlene (0.90 wt% natural boron). All three materials were in the form of disks, 1.960-in. in diam and 0.020-in. thick. 

Critical Parameters of Plutonium Systems, L. E. Hansen, E. D. Clayton (BNW)... 

A number of clean critical experiments have been performed in recent years on homc eneous plutonium systems. These experiments show that much of the criticality data that have been used as a guide for criticality safety, which were based on early experiments and calculations, should be revised. Particularly, the analysis of recent data shows that the values given for critical dimensions and masses can be generally in-... 

The paper also includes some. further checks on individual uranium and plutonium systems eiqieriments and investigates the limiting concentrations for k - 1 for mixed fuels and for variations Of Pu content in plutonium systems 1... 

L. E. HANSEN and E. D. CLAYTON, Critical Parameters of Plutonium Systems Fart II Interpretation, Nucl.Appl., 6, 381 (April 1969). 

In conclusion, this study demonstrates that the 19-energy-group structure yields results consistent with the ENDF/B-IV. msny-group and point cross-section data. Preliminary studies indicate that the final structure of the standard broad-gro q> cross-section set may need to be expanded to adequately treat plutonium systems. 

R. C. LLOYD and E. D. CLAYTON, Effect of Fixed and Soluble Neutrcm Absorbers on the Criticality Of Uranium-Plutonium Systems, ffucl. Sci. Eng., 62,726 (1977). 

The need for experimental criticality data on high-enriched uranium solution systems containing soluble neutron poisons has been indicated. Data have been presented previously on soluble poisons in plutonium systems and in low-enriched uranium systems. To supply data required on high-enriched uranium, a series of experiments. was performed at the PaciHc Northwest Laboratory (Critical Mass Laboratory) using high-enriched ( 85 wt% U) uranyl nitrate solution with cadmium nitrate as a soluble neutron... 

Experience with DTF-IV code indicates an accuracy of about 420 mk for plutonium systems GEM-3, an accuracy of about 30 nik. The results are summarized in Table II. Interaction calculations show that keff is <0.85 for the array of vessels filled to capacity with 175 g Pu/litre Pu(NOj)4 solution. 

Experimental data of the followii items are needed e ecially for Pu-U mixture systems, although information on similar items for Iow nriched uranium and plutonium systems is also not quite sufficient ... 

Further developments in hand include various group options, with direct links to Hansen-Roach, WIMS, ENDF/B, and other data sets, automatic keff search and optimization techniques, and other work on data and modeling aimed at the improvement of MONK 6 predictions for plutonium and mixed uranium/plutonium systems. 

Predictions for uranium systems are generally good, and the overestimation of keff that was generally a feature of calculations made with earlier versions of MONK has been significantly reduced. MONK 6 also performs better on most plutonium systems that have been studied flius far, but previous MONK 5 overprediction levels for mixed Sterns are only slightly reduced. 

The uraniimi fuel cycle for the uranium-plutonium system is a multicomponent system of chemical process operations that begins with mining uranium ore from the earth as... 

Initial reactor-fuel materials which have been considered [28] in uranium-plutonium systems are UO2SO4-D2O, U()2(X()3)2-D20, and UO3-D2O. Of these, the system which gives the highest conversion ratio is the one containing U0, j-D20. However, because of the relatively low values for ([ 235) r7(Pu ), it is presently considered that the attainment of a... 

The fertile-material concentrations and reactor diameters have essentially the same effects on coiu crsion ratio and fuel inventory for one-region uraiiiurn-plutonium. systems as they do for thorium breeder sy.stems however, since the rj s for and are lower than for it is more... 

Effect of Design Variables on Fuel Costs IN Uranium-Plutonium Systems... 

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