Thermal Analysis of a Simulated CANDU 37-Element Spent Fuel Bundle with Air Backfill

Abstract

Using a thermal mock-up of a simulated CANDU 37-element spent fuel bundle within a fuel basket, a series of experiments were performed to obtain the maximum fuel rod temperature along with the radial and axial temperature distributions within the fuel bundle. The main purpose of these experiments was to characterize the relevant heat transfer mechanisms in a dry, vertically oriented CANDU spent fuel bundle and to verify the MAXROT code developed earlier for the thermal analysis of a CANDU spent fuel bundle in a dry storage basket. A total of 45 runs were made with eight different power input to the 37-element heater rod bundle ranging from 5 to 40 W, while using six different band heater power input from 0 to 250 W to maintain the basket wall at a desired boundary condition temperature at the steady state. The experimental data were compared with the predictions of the MAXROT code to examine the code's accuracy and validity of assumptions. The MAXROT code explicitly models each representative fuel rod in a CANDU fuel bundle and treats the conductive and radiative heat transfer amongst the rods. Comparisons between the measured and predicted maximum fuel rod temperatures of the simulated CANDU 37-element spent fuel bundle for all 48 tests show that the MAXROT code slightly overpredicts the measured data within 2.8% with a mean deviation of 3.2 degrees C. (C) 2000 Elsevier Science S.A. All rights reserved.