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  • Author or Editor: Nak Kim x
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Abstract  

A Peak Identification and Activity Determination (PIAD) computer program has been developed. A new concept of peak significance is introduced and a great change has been made to the currently used associated gamma lines technique in calculating the confidence index; confidence factor is also given to the gamma line of a nuclide that is not seen in the spectrum. The program is written in Fortran IV under the operating system of RSX-11M.

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Abstract  

A NAA-PIXE combined analysis has been applied to the precise measurement of the concentrations of Nb and Ti in Nb–Ti alloy ingot. The ingot is used in the production of superconductors and the concentration should be controlled very strictly. The ingot cross section could be analyzed with an accuracy of better than 1% by the use of NAA for the preparation of standard samples and PIXE for the nondestructive rapid scan of the surface. The radial and azimuthal concentration profiles of the ingot could be obtained.

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Abstract  

A radiochemical separation method using an anion exchange resin has been applied to 4N grade tungsten for determining U, Th and 4 other elements. While tungsten remained in the resin, Na, K and As were separated with 0.05M HCl and 1M HF and then U, Th and Cr were eluted with 1M HCl and 1M HF. The separation yield of neptunium (U) was influenced largely by the amount of thorium, but this influence could be neglected as the concentration of the thorium was below 0.5g/ml. The content of these elements were calculated by a single comparator method using monitors, gold and cobalt. The detection limits of U and Th are 4.0 and 1.2 ppb, respectively.

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Abstract  

A radiochemical separation method has been applied for determining uranium, thorium and other impurities in molybdenum metallic powder. The impurities of Na, K, Sm, Cr, Zr, Cs, Rb, Zn, Fe, Co and La were separated with a cation exchange resin, and uranium and thorium were, then, separated with an anion exchange resin. The content of impurities were determined by a single comparator method using two monitors, gold and cobalt.

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Abstract  

The loss of trace elements during NAA of five liquid reagents, hydrofluoric acid, hydrochloric acid, nitric acid, hydrogen peroxide and deioniyed water, has been investigated using 17 radioactive tracers of46Sc,51Cr,54Mn,59Fe,60Co,645Zn,75Se,85Sr,95Zr,113Sn,124Sb,151Eu,160Yb,177Lu,182Ta,233Pa. Two kinds of container quartz and polyethylene have been used for irradiation and also for preconcentration of the reagents. The containers were cleaned before use by washing-leaching-rinsing procedure. The reagents were preconcentrated by subboiling evaporation under the infrared lamp in clean bench. The loss of trace elements has been revealed to be severer for the reagents of hydrochloric acid and nitric acid in the container of quartz than for the other cases, while that is lowest for hydrogen peroxide.

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Abstract  

For the separation of rare-earth elements from steel, with a cation exchange resin, separation experiments were performed on NIST reference materials of SRM-363 and SRM-364. Iron, Na, Cr, Mn, Co, Cu, As, Mo, Sb and W were separated in 2M hydrochloric acid, five rare-earth elements, La, Ce, Pr, Nd and Sm and three other elements, Hf, Zr and Ba were separated using 8M nitric acid. Each element was determined by a single comparator method using two monitors, gold and cobalt.

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