[en] For the long-term storage safety of the metallized spent fuels, which will be produced from an advanced spent fuel management process, developing in KAERI, metal uranium(U) and simulated metallized spent fuel(U-0.1Nd) are oxidized under pure oxygen environment at 150∼340 .deg. C. From the experimental results, the oxidation rates and activation energies for both of two metals are obtained and compared. And the XRD and Macroscopic examinations are also performed to observe the sequential oxidation phenomena of the simulated metallized spent fuel at 193 .deg. C

[en] The system analysis of an advanced spent fuel management process to establish a non-proliferation model for the long-term spent fuel management is performed by comparing the several dry processes, such as a salt transport process, a lithium process, the IFR process developed in America, and DDP developed in Russia. In our system analysis, the non-proliferation concept is focused on the separation factor between uranium and plutonium and decontamination factors of products in each process, and the non-proliferation model for the long-term spent fuel management has finally been introduced. (Author). 29 refs., 17 tabs., 12 figs

[en] The photoluminescent and cathodoluminescent (Zn, Cd)S phosphors are prepared by firing at 850⁰C in an atmosphere of N₂ gas for an hour. They are doped using (1) a CuCl activator, (2) a CuS activator, (3) a NaC1 flux, (4) both a CuC1 activator and NaC1 flux and (5) not doped with either one. The polycrystalline structure of ZnS phosphors powder is a mixed phase of both cubic and hexagonal: the phase of the powders of (Zn, Cd)S, (Zn, Cd)S; Cu and (Zn, Cd)S; Cu, C1 phosphors are the hexagonal pattern under the same firing condition. Measurements of CL and PL have been made at room temperature using cathode rays(-10 Kev) and 3650 A photons. These spectra showed shift of peak position from blue (green) to red as the CdS contents of the phosphors is increased. The observed luminescence centers are considered to be due to V⁺⁺sub(Zn) (B-center) Cu²⁺(C-Cu center), -oscillator (B-center) of SA emission and -oscillator (G-center) of SA these centers change quadratically with the molar fraction of (Znsub(1-x), Cdsub(x))S. (author)

[en] Photoluminescent (Znsub(1-x)Cdsub(x))S (where x=0, 0.2) phosphors are prepared by firing at 750⁰C, 850⁰C, 950⁰C and 1050⁰C in N₂ gas of atmospheric pressure for an hour. They are doped with (1) an activator Ag₂S, (2) both an activator Ag₂S and the flux NH₄Cl. The crystal structure of ZnS and (Zn, Cd)S powder is mixed phase of cubic and hexagonal. Photoluminescent cells are made with these phosphors and their emission spectra are measured at room temperature after these materials are excited with 3650 A light. These spectra are shifted from long range wavelength to short range wavelength as the firing temperature is increased. The NH₄Cl flux is found to serve the doping of the impurity energy levels and it has SA(self-activated) center in SA emission. (author)

[en] The photoluminescent (Zn, Cd)S: Ag phosphors are prepared by firing at 750⁰C, 850⁰C, 950⁰C and 1050⁰C in N₂ gas of atmospheric pressure for an hour. They are doped with(1) an activator Ag₂S(2) both an activator Ag₂S and each different flux; NaCl, NH₄Cl, NH₄Br. The crystal structure of (Zn, Cd)S:Ag phosphors powder is the mixed phase of cubic and hexagonal. The photoluminescent cells are made with these phosphors and their emission spectra are measured at room temperature after these materials are excited with 3650 A (3.4 eV) light. All these fluxes are found out to help the doping of the impurity energy level. The following results are also observed about (Zn, Cd)S:Ag phosphors. 1) Sufficient concentration of flux is enough with 10^-2mole/mole(Zn, Cd)S. 2) (Zn, Cd)S:Ag phosphors with flux NH₄Br is stronger intensity than that of the others. 3) The variation of PL intensity of (Zn, Cd)S:Ag phosphors against gr molecule of flux seems to increase with logarithmic function like. (author)

[en] The photoluminescent ZnS:Ag(Er,Pr) phosphors are prepared by firing at 850degC in N₂ gas of atmospheric pressure for an hour. They are doped with (1) an activator Ag₂S (2) both sensitizer Ag₂S and each different activators Ercl₃, Prcl₃. The crystal structure of ZnS:Ag(Er,Pr) phosphor powder is the mixed phase of cubic and hexagonal. The photoluminescent cells are made with those phosphors and their emission spectra are measured at room temperature after these materials are excited with 3650 A(3, 4eV) light. The following results are also observed about ZnS:Ag(Er,Pr) phosphors. (1) PL spectrum intensity of ZnS:Ag phosphors doped Er, Pr as ratio 10sup(-2) mole/mole ZnS is stronger than that of ZnS phosphors doped Er, Pr as ratio 10sup(-4) mole/mole ZnS. (2) As increase addional ratio of rare earth element, PL spectral peak of ZnS:Ag phosphor moved in short wave length. (3) PL spectrum intensity of ZnS:Ag phosphors are apeared differently for various impuriety (Ag, Er, Pr). (Author)

[en] At Korea Atomic Energy Research Institute (KAERI), we investigated the corrosion behavior of a series of Fe-Cr-Ni alloys with different chromium contents in molten LiCl and molten LiCl-25wt%Li₂O mixture at temperatures ranging from 923 to 1123 K. In molten LiCl, dense protective scale of LiCrO₂ grows outwardly while corrosion is accelerated by addition of Li₂O to LiCl. The basic fluxing of Cr₂O₃ by Li₂O would be the cause of accelerated corrosion. Because of low oxygen solubility and very high Li₂O activity in the molten LiCl-Li₂O mixture, Cr is preferentially corroded while Ni remains stable and thus, corrosion rate of the alloys in molten LiCl-Li₂O mixture increases with an increase in Cr content

[en] On this technical report, corrosion behavior of austenitic stainless steels of SUS 316L and SUS 304L in molten salt of LiCl-Li₂O has been investigated in the temperature range of 650 - 850 dg C. Corrosion products of SUS 316L in molten salt consisted of two layers, an outer layer of LiCrO₂ and inner layer of Cr₂O₃.The corrosion layer was uniform in molten salt of LiCl, but the intergranular corrosion occurred in addition to the uniform corrosion in mixed molten salt of LiCl-Li₂O. The corrosion rate increased slowly with the increase of temperature up to 750 dg C, but above 750 dg C rapid increase in corrosion rate observed. SUS 316L stainless steel showed slower corrosion rate and higher activation energy for corrosion than SUS 304L, exhibiting higher corrosion resistance in the molten salt. In heat-resistant alloy, dense protective oxide scale of LiCrO₂ was formed in molten salt of LiCl. Whereas in mixed molten salt of LiCl-Li₂O, porous non-protective scale of Li(Cr, Ni, Fe)O₂ was formed. (Author). 44 refs., 4 tabs., 16 figs

[en] The section 2 of the SI cycle (H₂SO₄ decomposition process) consists of several processes including (i) the concentration of H₂SO₄ solution, (ii) the vaporization of concentrated H₂SO₄ solution, (iii) decomposition of H₂SO₄ solution into SO₃ and H₂O at around 400∼500 deg. C, and (iv) the decomposition of SO₃ into SO₂ and O₂ at around 850 deg. C under the existence of catalyst. The unit models have been developed for evaporation and decomposition of H₂SO₄ in SI cycle with the chemical process simulator. The overall simulation flow sheet has been developed and several sensitivity analyses have been done for the process equipment. (author)

[en] A study on the precipitation of uranium by oxalic acid was carried out in a multicomponent solution. The precipitation method is usually applied to the treatment of radioactive waste and the recovery of uranium from a uranium-scrap contaminated with impurities. In these cases, the problem is how to increase the precipitation yield of target element and to prevent impurities from coprecipitation. The multicomponent solution in the present experiment was prepared by dissolving U, Nd, Cs and Sr in nitric acid. The effects of concentrations of oxalic acid and ascorbic acid on the precipitation yield and purity of uranium were observed. As results of the study, the maximum precipitation yield of uranium is revealed to be about 96.5% and the relative precipitation ratio of Nd, Cs and Sr versus uranium are discussed at the condition of the maximum precipitation yield of uranium, respectively. (author). 11 refs., 5 figs., 1 tab