Proceedings of the
International Conference on Mechanical Engineering 2009
(ICME2009) 26- 28 December 2009, Dhaka, Bangladesh

ICME09-TH-32

NUMERICAL ANALYSIS FOR TEMPERATURE ASSESSMENT OF
THE IRRADIATED TEO2 POWDER IN THE DRY CENTRAL
THIMBLE OF THE 3MW TRIGA MARK-II RESEARCH REACTOR

M.S.Islam1, S.B.Samee2, M.M.Uddin1 and M.Mamun2
1Reactor Operation and Maintenance Unit, Atomic Energy Research Establishment, Ganakbari, Savar, ,
Dhaka, Bangladesh
2 Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh

ABSTRACT

Temperature assessment during irradiation of 50g TeO2 powder in a sealed quartz vial holding with aluminum specimen container (Al-Can) in the dry central thimble (DCT) of the reactor core is performed numerically using a CFD tool. The reactor power is considered full power at 3MW(th). The geometrical configuration of the DCT is; length = 8 m, I.D = 33.88 mm and O.D = 38.1 mm and there is like a dog-leg bend. The length of the quartz vial as well as Al-Can are 75.2 and 95.1 mm, respectively. The gap between the quartz vial and Al-Can, Al-Can and DCT are 0.92 and 4.49 mm, respectively and there is air in the gaps. A 2D and 3D model geometry of the DCT with a narrow gap between quartz vial and Al-Can (0.92 mm) and Al-Can and DCT (4.49mm) is generated by simulating the existing cooling capacity of the DCT. The laminar viscous model and the turbulent RNG k−∈ model are applied for the 2D and 3D models. Radiative heat transfer was modeled using S2S model for the 2D case provided with no hole on the surface of the Al-Can and DTRM is used for the 3D case provided with several holes on the surface of the Al-Can. It has found that the highest centerline temperature of TeO2 powder is found in the laminar viscous model of the existing cooling geometry which is about 662 0C when no hole is present on the surface of the Al-Can. On the other hand, RNG k−∈ model shows a maximum centerline temperature of 658 0C under the same condition. However, no significant difference has found in temperature distribution between the laminar viscous and the turbulent RNG k−∈ model. In the 3D modeling, when several holes present on the surface of the Al-Can under the same condition, it has found that the centerline temperature along with temperature at different zones decreases considerably. This is because of the more favorable heat transfer atmosphere than the sealed Al-Can (without hole). The detailed numerical analyses under different cases along with experiments under the same cases may really provide a better cooling technique for the DCT of the reactor which consequently does help increasing the I-131 production and other related R&D activities with assured safety of the reactor operation.

Keywords: Temperature assessment, Irradiation, Numerical analysis, Safety, Reactor Operation.

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