Measured and Calculated Heating and Dose Rates for the Hfir Hb4 Beam Tube and Cold Source

Abstract

The High Flux Isotope Reactor at the Oak Ridge National Laboratory was upgraded to install a cold source in horizontal beam tube number 4. Calculations were performed and measurements were made to determine nuclear heating within the cold source and dose rates within and outside a shield tunnel surrounding the beam tube. This report briefly describes the calculations and presents comparisons of the measured and calculated results. Some calculated dose rates are in fair-to-good agreement with the measured results, while others, particularly those at the shield interfaces, differ greatly from the measured results. The calculated cold source nuclear heating is in good agreement with the measured heating. xi

Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

“…Maximum local fission rate densities of 2.26×10 15 and 1.40×10 15 fissions/ (cm 3 U-10Mo • s) were calculated for the BOC and EOC cores, respectively; both of these maxima are located at the inner radial edge of the IFE on the core horizontal midplane. Assuming conservatively that 100% of the total reactor power (100 MW) is deposited in the fuel meat, these maximum fission rate densities would correspond to power densities of ~ 72.40 and 45.30 kW/(cm 3 UMo), respectively.…”

“…5.5 as a function of the axial distance from the core horizontal midplane. A maximum BOC local fission rate density of 1.77×10 15 fissions/(cm 3 U-10Mo • s) was calculated, and this maximum is located at the inner radial edge of the IFE on the core horizontal midplane. Assuming conservatively that 100% of the total reactor power (100 MW) is deposited in the fuel meat, this maximum fission rate density would correspond to a power density of about 56.96 kW/(cm 3 UMo).…”

“…Version 2.0.2 was utilized in these studies to couple the MCNP5 code to the point depletion and decay code ORIGEN 2.2 [12]. VESTA has been selected as the primary depletion tool for HFIR core analysis because of its ability to simulate the vertical control element movement necessary to maintain critical conditions during the fuel cycle and because extensive resources have been devoted to benchmarking MCNP models of HFIR [13][14][15][16].…”

“…and 1.32×1015 fissions/(cm 3 U-10Mo • s) for Alternate 6 with 3.4g 10 B; 2.12×10 15 and 1.32×10 15 fissions/(cm 3 U-10Mo • s) for Alternate 6 with 3.6g 10 B; and 2.01×10 15 and 1.34×10 15 fissions/(cm 3 U-10Mo • s) for Alternate 6 with 4.6g 10 B.…”

Preliminary Evaluation of Alternate Designs for HFIR Low-Enriched Uranium Fuel

“…Maximum local fission rate densities of 2.24×10 15 and 1.33×10 15 fissions/(cm 3 U-10Mo • s) were calculated for the BOC and EOC cores, respectively, for Alternate Design 3 with 3.4g 10 B; both of these maxima are located at the inner radial edge of the IFE on the core horizontal midplane. For Alternate 3 with 4.6g 10 B, the maximum local fission rate densities at BOC and EOC are 2.10×10 15 and 1.34×10 15 fissions/(cm 3 UMo s); the locations of these maxima are the same as for the case with 3.4g 10 B. Assuming conservatively that 100% of the total reactor power (100 MW) is deposited in the fuel meat, the maximum fission rate densities would correspond to power densities of ~ 71.84 and 42.68 kW/(cm 3 UMo), respectively, for Alternate 3 with 3.4g 10 B and to ~ 67.28 and 43.04 kW/(cm 3 UMo), respectively, for Alternate 3 with 4.6g 10 B.…”