Heat load measurement in the vertical hole for installation of Hanaro CNS

For heat load determination in the CNS hole of Hanaro reactor, the following technique were executed: 1) Measurement of thermal, epithermal and fast neutron fluxes by activation method 2) Measurement of heating rate by γ-quantum absorption by Bragg-Gray ionization chamber 3) Calculation of a neutron spectrum by Monte-Carlo method and normalization on experimental neutron fluxes 4) Consideration of the difference between the real and measurement condition. For γ-heating rate measurement the Bragg-Gray ionization chamber (IC-Gray) was used, which was developed in PNPI, Russia. The results of thermal and fast neutron fluxes for both schemes (experimental and CNS model) are in a good agreement with those calculated by MCNP, therefore the heat release data in hydrogen from neutron have high reliability. Analysis of heat release data from γ-rays has shown that the experimental results are underestimated. The cause of underestimation can be explained by two cases. One is the different circumstance that the measurement was executed in CNS channel filled with light water, but the calculation was carried out in the vacuum channel. And the other is the fact that calibration of IC-Gray was executed in the different range from that of real measurement. Therefore the measurement by IC-Gray was used only for calibration of the calculation code, and the calculation data by MCNP will be used as a ground data of design. (author)