In Korea, ten PWR and two CANDU reactors are in operation, six PWRs and two CANDUs are under construction, and eight more nuclear power plants are scheduled to be built by 2010. Two PWRs will also be built in North Korea. Ten operating PWRs comprise of eight Westinghouse type reactors and two ABB CE type reactors. Korea Nuclear Fuel Company (KNFC) is designing and manufacturing nuclear fuel for all operating PWRs and CANDUs in Korea. Since 1985, seven different types of PWR fuel have been designed and manufactured by KNFC with a 200ton/year manufacturing facility. To meet the increasing demand, KNFC recently completed a new PWR fuel manufacturing facility with an annual production capacity of 350ton and a new CANDU fuel manufacturing facility with a 700ton/year production capacity.
The Korean government initiated a "Long-term Nuclear R&D Program" in 1992. The nuclear R&D program is being carried out through concerted efforts by industry, research institutes and universities. Major R&D projects in the nuclear fuel area include a new fuel cycle called DUPIC (Direct Use of spent PWR fuel in CANDU reactors), a Korean next generation fuel for PWRs, an improved CANDU fuel and an improved research reactor fuel for HANARO (High-flux Advanced Neutron Application Reactor).

抄録全体を表示

A radiation digital waveform processing system has been studied using a fast signal digitizer on the VXIbus system. The proposed system is able to measure pulse signals at the maximum counting rate of over 160 waveforms per second. When applying to an n-γ pulse shape discrimination for an NE213 scintillation detector, more refined pulse shape discrimination can be easily accomplished by adjusting the discrimination parameter on the basis of energy of each incident radiation.

抄録全体を表示

This paper deals with transient boiling heat transfer to mist flow of air-water mixture from hot metals coated with a thin layer of low thermal conductivity material. The test specimens used for the present experiment are silver and stainless steel disks whose heat transfer surface is coated with a refractory paint over the thickness range, 3-38μm. The heated disk of 750°C is plunged vertically into the mist flow and is cooled down to the temperature of air-water mixture under atmospheric pressure. The mass velocity of water ranges between 0.04 and 0.78kg/m²-s. The air velocity is varied from 3 to 7m/s. The coating produces a great enhancement in heat transfer, especially in transition and film boiling regions. This enhancement becomes higher with increasing coating thickness since minimum film boiling temperature becomes higher and an earlier transition from film to transition boiling occurs. Heat transfer is more enhanced as mass velocity of water increases although it has a weak dependence on air velocity.

抄録全体を表示

Two kinds of cesium uranates, which are often predicted by thermochemical calculations to be formed in irradiated oxide fuels with high oxygen potentials, were prepared from U₃O₈ and Cs₂CO₃ to determine the thermal expansions and the thermal conductivities. The lattice parameters of tetragonal Cs₂UO₄ and monoclinic Cs₂U₂O₇ were measured by the high-temperature X-ray diffraction method as a function of temperature. The linear thermal expansions of Cs₂UO₄ and Cs₂U₂O₇ obtained from the temperature dependencies of the lattice parameters were 1.2% and 1.1% from room temperature to 973 and 1, 073K, respectively. The thermal diffusivities of Cs₂UO₄ and Cs₂U₂O₇ were measured on the disk-shaped samples by the laser flash method as a function of temperature. The thermal conductivities were evaluated from the measured thermal diffusivities and the bulk densities, and the specific heat capacity available in literature. The thermal conductivity of Cs₂UO₄ corrected for 100%TD was 1.2W/m•K at 980K and that of Cs₂U₂O₇ was 0.94W/m•K at 1, 093K, which are about 30% and 27% of that of UO₂, respectively.

抄録全体を表示

The melting (solidus) temperatures of irradiated mixed oxide fuels were measured and the compositions of the fuels on the temperature measurement date were calculated. The fuels contained about 29wt% Pu initially and were irradiated up to 124GWd/t in the experimental fast reactor JOYO. A melting temperature correlation was obtained by an experimental regression analysis using 21 measurements:
Τ_m=3, 133.8-460Χ₁-980Χ₂-0.66Χ₃+0.0013(Χ₃)²,
where Τ_m, is the expected melting temperature (K), Χ₁ the plutonium fraction (Pu/(Pu+U)) and Χ₂ the americium fraction (Am/(Pu+U+Am)) at the measurement, and Χ₃ the burnup (GWd/t). The equation shows that the melting temperature decreases by 5, 4, and 3K per 10GWd/t at 50, 100 and 150GWd/t, respectively. The effects of actinides, such as Pu and Am, on melting temperature could be explained by an ideal solution model. However, the decreases caused by soluble fission products could not be well explained in terms of the ideal solution model.

抄録全体を表示

Influence of the irradiation on the corrosion behavior of stainless steel (type 304ULC) in boiling nitric acid solution was examined by using ⁶⁰Co γ-ray source. It was found from the experimental results that radiolysis products of nitric acid (NO_χ, HNO₂) resulted from the γ-ray irradiation made the environment in the bulk solution more reducing one. On the other hand, corrosion rate of 304ULC was slightly enhanced by the irradiation, which being trivial from the engineering viewpoint. From the result of an AC impedance measurement, this corrosion enhancement was inferred as caused by an enhancement in the current across the passive film by the γ-ray irradiation on the stainless steel surfaces.

抄録全体を表示

In summary, the proposed model showed the reasonably accurate predictions for various grids investigated here. It yields also better predictions than others do. Even some improvements are needed in the model, however, it is concluded that the proposed model for pressure drop can provide sufficiently good approximation for grid optimization and design calculation in advanced grid development.

抄録全体を表示

Catalytic breeders were produced by impregnating lithium silicate with either platinum or palladium. The isotope exchange reactions between molecular protium and gaseous predeuterated water over these new breeders were found to be very fast even at temperatures far below 400°C.

抄録全体を表示

The supercritical fluid extraction (SFE) of heavy metals from acidic aqueous solution has attracted interest lately^(1)-(5). In the present study₁, supercritical CO₂ was directly applied to lanthanide oxide as an extraction solvent. Lanthanide metals were extracted from lanthanide oxides (Nd₂O₃ and Gd₂O₃) by using supercritical CO₂ including tri-n-butylphosphate (TBP) and HNO3 complex.

抄録全体を表示