Thermal analysis of a simulated CANDU 37-element spent fuel bundle with air backfill

Using a thermal mock-up of a simulated CANDU 37-element spent fuel bundle w ithin a fuel basket, a series of experiments were performed to obtain the m aximum fuel rod temperature along with the radial and axial temperature dis tributions within the fuel bundle. The main purpose of these experiments wa s to characterize the relevant heat transfer mechanisms in a dry, verticall y 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 stor age basket. A total of 45 runs were made with eight different power input t o 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 wa ll at a desired boundary condition temperature at the steady state. The exp erimental data were compared with the predictions of the MAXROT code to exa mine the code's accuracy and validity of assumptions. The MAXROT code expli citly models each representative fuel rod in a CANDU fuel bundle and treats the conductive and radiative heat transfer amongst the rods. Comparisons b etween the measured and predicted maximum fuel rod temperatures of the simu lated CANDU 37-element spent fuel bundle for all 48 tests show that the MAX ROT code slightly overpredicts the measured data within 2.8% with a mean de viation of 3.2 degrees C. (C) 2000 Elsevier Science S.A. All rights reserve d.