[en] A study of the Zircaloy-4 reaction with H₂O/H₂ mixture gas is carried out by using TGA (Thermo Gravimetric Apparatus) to estimate the hydrogen embrittlement which can possibly cause catastrophic nuclear fuel rod failure. Reaction rates are measured as a function of H₂/H₂O. In the experiments reaction temperature is set at 500 .deg. C and total pressure of the mixture gas is maintained at 1 atm. Experimental results reveal that hydriding and oxidation reaction are competing. In early stage, hydriding kinetics is faster than oxidation, however, oxidant in H₂O forms oxide on the surface as steam environment is maintained, thus, this growing oxide begins to protect the zirconium base metal against hydrogen permeation. In this second stage, the total kinetic rate follows enhanced oxidation kinetics. In the final stage, it is observed that the oxide is broken down and massive hydriding takes place through the mechanical defects in the oxide, whose kinetics is similar to pure hydriding kinetics. These results are confirmed by SEM and EDX analysis along with hydrogen concentration measurements

[en] Burnup of spent nuclear fuel assembly J14 discharged from Kori-1 Nuclear Power Plant was determined by using Nondestructive Gamma-ray spectrometry combined with computer code calculation, and was compared and evaluated with the chemically determined burnup values in order to verify the precision of NDT method. As a result, nondestructively determined burnup values appeared to be agreed within 4.8 % error bound when the destructive chemical burnup value is referenced

[en] The usage inspection of the KN-12 spent nuclear fuel transport package was performed to receive the license for reuse. According to the Korea Atomic Energy Act, all type B transport package should receive and pass the usage inspection every five years. The KN-12 transport cask was designed to transport twelve spent PWR fuel assemblies under wet and dry conditions. The cask was developed and licensed in 2002 in accordance with the Korea and the IAEA's safe transport regulations. The areas of usage inspection include: visual inspection, nondestructive weld inspection, load test, maximum operating pressure test, leakage test, shielding test, thermal test, external surface contamination test. In the results of the usage inspection, the damage or defect could not found out and the performance of the cask was maintained according to the requirements of the regulation. Therefore, the usage inspection was successfully performed to acquire the license for the reuse

[en] The usage inspection of the KN-12 spent nuclear fuel transport package was performed to receive the license for reuse. According to the Korea Atomic Energy Act, all type B transport package should receive and pass the usage inspection every five years. The KN-12 transport cask was designed to transport twelve spent PWR fuel assemblies under wet and dry conditions. The cask was developed and licensed in 2002 in accordance with the Korea and the IAEA's safe transport regulations. The areas of usage inspection include: visual inspection, nondestructive weld inspection, load test, maximum operating pressure test, leakage test, shielding test, thermal test, external surface contamination test. In the results of the usage inspection, the damage or defect could not found out and the performance of the cask was maintained according to the requirements of the regulation. Therefore, the usage inspection was successfully performed to acquire the license for the reuse

[en] Nuclear materials accounting and verification in radiochemical processing facilities is essential, because it is the first possible time in the nuclear fuel cycle that plutonium can be measured. In these facilities, effective nuclear materials accounting systems and international safeguards inspections rely heavily upon nondestructive assay measurements. Therefore, it is important to know whether the radiation-based nondestructive assay (NDA) techniques for Advanced Spent Fuel Management Process are applicable or not. As a result of reviewing the existing NDA techniques for nuclear material accounting, it was revealed that γ-ray spectrometry, x-ray fluorescence/ densitometry and calorimetry techniques are not applicable to the advanced spent fuel management process because of the size of the measuring devices installed in a hot cell and the samples including some fission products. Therefore, the neutron technique is only applicable to this processing facility. The results reviewed in this study can be used to design a hot cell for the advanced spent fuel management process

[en] Horizontal burnup gradients were determined by gamma-ray spectrometry for the PWR spent nuclear fuel assemblies discharged from Kori Unit-1 and Unit-2 power reactors in 1985 and 1992, respectively. Gamma-ray Measurements of 4 faces of the fuel assembly were carried out using a under-water burnup measuring device in a pool of PIEF at KAERI. As a result of data analysis, horizontal burnup gradients of F02 assembly burned in Kori Unit-1 for 3 cycles were 11 % for the 1-3 faces and 7% for the 2-4 faces, and those of J44 assembly burned in Kori Unit-2 were 4 % and 19%. These values will be employed to determine the average burnup of fuel assembly with the axial burnup distribution determined by gross gamma scanning

[en] Errors in determining the ratio of Eu-154 to Cs-137 which are burnup monitors were evaluated after obtaining the gamma-ray spectra from the specimen taken from spent nuclear fuel assembly G23 discharged from Kori-1 in 1986. The errors of gamma-ray detection, regression analysis of relative efficiency and isotope ratio determination as the major error factors were considered in this work. As a result of the error analysis, error in determining the Eu-154/Cs 137 ratio appeared to be within 5%

[en] Burnup of the fuel rod taken from spent fuel assemblies C15, G23 and J14 discharged from Kori-1 was examined by destructive chemical assay and determined by Nd-148 mass spectrometry method. And then they were compared with the calculated burnup of ORIGEN-S for the code verification by using activity ratio Eu-154/ Cs-137. As a result of the comparison, burnup of Nd-148 chemical method has a good agreement with the calculated burnup within 1% error in C-15 and G23 rod, and within 8% in the J-14 rod

[en] To analyze harmful factors for the reduced uranium metal, which was mainly composed of uranium, several basic properties such as microstructure, immiscibility, thermal, fission product effects were surveyed. And the oxidation properties of metal uranium and uranium alloys were also studied to select alloying elements for producing a stable uranium metal

[en] The Advanced spent fuel Conditioning Process (ACP) is under development for the effective management of spent fuel which had been generated in nuclear plants. The ACP needs a hot cell where most operations will be performed. To give priority to the environment safety, radiation doses evaluation for the radioactive nuclides were preliminarily performed in both normal operation and accident case. The evaluation result shows a safe margin for regulation limits and SAR limit of IMEF where this facility will be constructed