Indian PHWR Fuel

The fuel bundles of PHWRs India are short cylindrical assemblies. Each coolant channel has 12 or 13 such fuel bundles.
220 MWe Reactor fuel : 19-element fuel bundle design. Stack of cylindrical sintered natural uranium dioxide fuel pellets, inside a zircaloy fuel tube and sealed at both ends by end plugs. The fuel elements are arranged in concentric rings and are assembled together by welding them to an end plate on each side to form a bundle. The bundle length is 495 mm and the weight is 16 Kgs. The spacers and bearing pads are attached to fuel elements by spot welding. The inside surface of fuel sheath is graphite coated to decrease the fuel element failure rate due to power ramps.
540 MWe and 700 MWe Reactor fuel: 37 element fuel bundle design is an extension of the closed packed 19 element fuel bundle. One more ring of elements has been added. All the elements are of a small diameter of 13 mm. The bundle has been designed to generate a bundle power of about 1 MW.

On power bi-directional fuelling is done using two fuelling machines, one at either end of the coolant channel. Pressure tubes containing a string of short length fuel bundles and the on-power refueling permit flexibility in choosing fuel designs and in-core fuel management parameters to maximize fuel utilization. A defective fuel can also be identified and removed from the reactor while it is in operation.

The unit energy cost distribution for PHWRs:

The fuel consumption cost:- 18% to 25% of unit energy cost.

The Capital cost:- typically 27%, .

The operation and maintenancecost:-typically10%

The heavy water costs :- Typically 32% .

Paradox:
PHWRS are optimally designed from neutron economy considerations, uses natural uranium fuel economically in comparison to other types in terms of extracting maximum energy per gram of natural uranium . Still the fuel consumption cost is high due to high cost of indigenous raw meterial. MOX fuels