Selahaddin Orhan Akansu

Investigation of heat transfer and pressure drop for various obstacles in a rectangular‐sectioned 90° bend

Purpose – Re<95,000 based on hydraulic diameter, heat transfer and turbulent flow through a rectangular‐sectioned 90° bend was investigated numerically and experimentally. To develop turbulence level, square prism and cylindrical obstacles was placed in the center of the bend.Design/methodology/approach – For heat transfer, uniform heat flux of 5,000 W/m2 from bend surfaces is assumed. Numerical analysis was realized for both the turbulent flow and heat transfer. For numerical study, FLUENT 6.1.22 code, RSM turbulence model, hybrid hexahedral‐tetrahedral cell structures and uniform inlet velocity assumption were selected. For the pressure distribution in the bend and velocity profile at the outlet of the bend, the experiments was carried out by means of manometers with ethyl alcohol, Mano‐air 500 Equipment and pitot‐static tube.Findings – There was a high level of validation obtained between the numerical and the experimental results. Thereby, the mentioned numerical calculation method can be used most en...

NEUTRONIC ANALYSIS OF LITHIUM HYDRIDE (LiH) MATERIAL IN A (D, T) DRIVEN HYBRID BLANKET

Abstract In this study, neutronic performance of Lithium Hydride (LiH) material is analyzed in a D‐T driven hybrid blanket cooled by flibe (Li2BeF4). The hybrid blanket is fuelled by UO2 from LWR fuel rod, LWR spent fuel rods and CANDU spent fuel rods. Energy production, tritium breeding, neutron leakage and fissile fuel breeding are considered. Volume fractions are selected as 1, 2, 3, 4 and 5. LiH thickness is increased from 0 to 80 cm. The number of rows is selected as 10 to 20. When the volume fractions increase, TBR values decrease. When the LiH thickness reaches 50 cm, TBR values reach the point of saturation. At this thickness, TBR values of Model‐ II (P. 4) are higher than those of Model‐I (P. 4). The M energy multiplication factor has nearly the same tendency in both models. Neutron leakage values of Model‐II (for DRLiH = 50 cm) are lower than that Model‐I. Although the fissile fuel breeding rate values of Model‐I and Model‐II are almost the same, the values of Model‐I are a little higher than Model‐II. Therefore, it is concluded that LiH material is suitable for using, when neutronic behaviour is considered.

Investigation of neutronic performance of a peaceful nuclear explosive reactor (PACER) evaluating UF4 and ThF4 nuclides

In this study, neutronic behaviour of a peaceful nuclear explosion reactor (PACER) producing approx 1·2 GWe power from fusion explosions is analysed considering ThF4 and UF4 as fissile zones. UF4 and ThF4 are put in to the system adjacent to the inner-side of the flibe coolant zone positions (distance between explosive region and fuel zone,DR = 50, 100, 200, 400, 500 and 700 cm). Flibe percentages are taken to be 25, 50, 75 and 100%. It is found that optimum combinations of fissile zone thickness, coolant zone position and coolant percentages are 10 cm, 200 cm and 25% flibe for UF4 and 10 cm, 50 cm and 25% flibe for ThF4. The behaviour of fuels mentioned above has been observed over a period of 30 years at discrete time intervals, δt = 30 days. In the case of UF4,M values atDR = 200 cm reach 5·35, 5·22,4·88, and 4·88 from 3·12, 2·98, 2·83 and 2·83, for 25,50,75,100% flibe respectively. For ThF4 atDR = 50 cm,M values reach from 1·61, 1·54, 1·50 and 1·46 to 1·93, 2·00, 2·04 and 1·99 for 25, 50, 75, 100% flibe respectively. Cumulative fissile fuel breeding (CFFE) values reach up to 5·5 from 0·7 atDR = 200 and 25% case for UF4, and up to 6·36% from 0%, atDR = 50 and 25% flibe, for ThF4, at the end of the operation period