[en] The Savannah River Site (SRS) is part of the U.S. Department of Energy (DOE) complex. It was constructed in the early 1950's to produce special nuclear materials (such as plutonium-239 and tritium) used in the production of nuclear weapons. The 310-square-mile site is located in South Carolina, about 15 miles southeast of Augusta, Georgia. The production of nuclear materials at SRS continued for more than 40 years. However, the end of the Cold War caused a downsizing of this original national defense mission. Current missions are focused on: (1) nuclear weapons stockpile stewardship which emphasizes science-based maintenance of the country's nuclear weapons stockpile; (2) nuclear materials stewardship for management of excess nuclear materials, including transportation, stabilization, storage, and safe and secure disposition; and (3) environmental stewardship involving management, treatment, and disposal of radioactive and nonradioactive wastes resulting from past, present, and future operations

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[en] Quality of portland cement concrete can be increased if water/cement ratios are reduced; however, this increase is only achieved if concrete is adequately consolidated. This study was conducted to develop a device to permit continuous automatic monitoring of the degree of consolidation during pavement construction. A literature search identified several candidate techniques, the most feasible being a nuclear backscatter technique to measure concrete density. A prototype instrument was developed with a 500mCi source of Cesium (137) and a sodium iodide/photomultiplier sensing unit. The sensor head is located 1 inch (25.4 mm) above the concrete. It is moved back and forth across the width of the pavement by a traversing mechanism mounted to the back of a slip-form paver. Density is recorded on chart paper. The CMD (Consolidation Monitoring Device) is capable of sensing and displaying changes in density while traversing over the pavement surface at 17 fpm (0.086 m/s). It can duplicate core density measurements within a + or -2-1 pcf (+ or -36 kg cu m) confidence range

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[en] The isotope shifts of atomic K x rays were measured for pairs of the six mercury isotopes with A = 198, 199, 200, 201, 202, and 204, using a curved crystal spectrometer. The changes of the nuclear charge radii were derived in terms of delta < r² > and delta R/sub k/ and compared with optical and muonic isotope shift data. From results, a renormalization of the optical data was obtained. 11 references

[en] The temperature dependences of the crystal structure and superstructure intensities in sodium nitrate, mineral name nitratine, NaNO₃, were studied using Rietveld structure refinements based on synchrotron powder X-ray diffraction. Nitratine transforms from R(bar 3)c to R(bar 3)m at T_c = 552(1) K. A NO₃ group occupies, statistically, two positions with equal frequency in the disordered R(bar 3)m phase, but with unequal frequency in the partially ordered R(bar 3)c phase. One position for the NO₃ group is rotated by 60^o or 180^o with respect to the other. The occupancy of the two orientations in the R(bar 3)c phase is obtained from the occupancy factor, x, for the O1 site and gives rise to the order parameter, S = 2x ? 1, where S is 0 at T_c and 1 at 0 K. The NO₃ groups rotate in a rapid process from about 541 to T_c, where the a axis contracts. Using a modified Bragg-Williams model, a good fit was obtained for the normalized intensities (that is, normalized, NI^1/2) for the (113) and (211) reflections in R(bar 3)c NaNO₃, and indicates a second-order transition. Using the same model, a reasonable fit was obtained for the order parameter, S, and also supports a second-order transition.

[en] Most probable values of K and L x-ray line width have been determined by constructing least-squares computer fits to the available experimental points plotted against atomic number. The numerical values of line width, thus obtained, for the K x-ray and the L x-ray lines are presented in the table. The experimental points, the least-squares smooth curves, and the results of the most recent theoretical predictions are presented in graphical form

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[en] Experimental results on K/sub α/ x-ray isotope shifts are summarized. The delta(r²) values of the nuclear charge distribution, as derived from the data, are presented. A combination of x-ray and optical isotope shifts, in some cases, yields an improved accuracy for delta(r²). The mass-shift corrections to the x-ray isotope shifts are presented. (U.S.)