Question

assuming that linear heat rate, fuel outside temperature and outside diameter for a solid fuel pellet and an annular fuel pellet are the same, how does the maximum temperature compare between the two pellet? Why?

assuming that linear heat rate, fuel outside temperature and outside diameter for a solid fuel pellet and an annular fuel pellet are the same, how does the maximum temperature compare between the two pellet? Why?

Answer 1

Solution :

There is an inconsistency in temperature of the coolant flow resulting from the unbalanced thermal stress acting on the solid fuel pellet. This potentially damages the solid fuel pellet. In addition to the above inconsistency, there exists quite huge temperature disparity between coolants flowing in the neighbor region of the cladding surface and central portion arge temperature of the channel. In order to transfer the same quantity of energy (heat) generated by nuclear fission, the higher temperature of the coolant near the surface of the solid pellet will increase the fuel solid surface temperature.

Now, The maximum temperature of the annular ring occurs near the mid-point of the annular field. Also, the temperature of the inner surface of the annular fuel pellet is higher in comparison to the outer one. This implies that, the temperature gradient at the inner side of the mid point are smaller than those of the outer side.

Thus, annular fuel pellets have less maximum temperature when compared with solid fuel pellets because of their convective cladding. Hence, they posses a superior degree of safety in an accidental situation of nuclear power plant.