Analysis of neutron dosimetry from Kori Unit 4 capsule U, V and X in accordance with USNRC Reg. Guide DG-1025

This analysis note has been prepared in order to provide an evaluation of neutron dosimetry from Kori unit 4 reactor vessel surveillance capsule U, V and X, withdrawn at the end of the first, fourth and eighth fuel cycle. The analysis was carried out in accordance with the requirements of U.S Regulatory Guide DG-1025, and also based on the results of the calculation note for the Korea nuclear power plant with 3-loop reactor documented in this analysis note. The evaluation results are as follows; Capsule X withdrawn at the end of the eighth fuel cycle was irradiated for a period of 6.93 effective full power years(EFPY) and experienced the integrated fast neutron fluence(E>1.0Mev): 3.42E+19±13% n/cm2. The re-evaluation of dosimetry from Capsule U and V indicated that the surveillance specimens had been irradiated for a period of 0.81EFPY and 3.20EFPY and experienced the integrated fast neutron fluence(E>1.0Mev): 5.15+18±13%n/cm2, respectively. With respect to the uncertainty evaluation of the fast neutron flux, the overall uncertainty for the Kori unit 4 Capsule X located in 17.0 degree was revealed 13% uncertainties, and the average bias factor (Measured/Calculated ratios for Φ(E>1.0Mev) was calculated by 0.92. The bias factor of this magnitude is consistent with experience using the BUGLE-93 cross-section library, and the results of the sensitivity study fully met the requirements of U.S Regulatory Guide DG-1025. (author). 27 tabs., 9 figs., 4 refs