Critical power enhancement system for a pressurized fuel channel type nuclear reactor using CHF enhancement appendages

A fuel bundle assembly for use in a nuclear reactor using pressurized water as a coolant flowing in a plurality of fuel channels, said fuel bundle assembly comprising:

• a fuel bundle containing a plurality of elongated fuel elements, each of said fuel elements having opposed ends and a peripheral surface extending the length between said opposed ends;
• at least one spacer for separating said fuel elements from each other;
• at least one bearing pad attached to outer fuel elements for providing load bearing to said fuel bundle;
• and
• at least one CHF enhancement appendage attached to each of certain fuel elements along said length thereof and projecting outwardly from the peripheral surface of said each fuel element for generating turbulence in said coolant flowing along said length of said fuel bundle downstream of the locations of said CHF enhancement appendage.

A pressurized fuel channel type nuclear reactor which uses pressurized water as a coolant, said reactor comprising:

• an elongated pressure tube defining a fuel channel therethrough, said pressure tube having a length, an inlet for introducing said coolant into said fuel channel, and an outlet for discharging said coolant from said fuel channel;
• a plurality of elongated fuel bundles contained within said pressure tube, each of said fuel bundles containing a plurality of fuel elements therein, each of said fuel elements having opposed ends and a peripheral surface extending the length between said opposed ends, said length of each fuel element being parallel to said length of said pressure tube;
• a plurality of spacers for separating said fuel elements from each other;
• a plurality of bearing pads attached to outer fuel elements for providing load bearing to said fuel bundles;
• and
• at least one appendage provided on each of certain fuel elements along said length thereof and projecting outwardly from the peripheral surface of said each fuel element into coolant flow space within said fuel channel surrounded by fuel elements, for generating turbulence in said coolant flowing along said length of each of said fuel bundle downstream of the locations of said CHF enhancement appendages.

A critical power enhancement system for a nuclear reactor which uses pressurized water as a coolant, said system comprising:

• a pressure tube defining a fuel channel therethrough, said pressure tube having a length, an inlet for introducing said coolant into said fuel channel, and an outlet for discharging said coolant from said fuel channel;
• a plurality of fuel bundles contained within said pressure tube, said fuel bundles being separated from each other forming water gaps therebetween, through which said coolant flows, each of said fuel bundles comprising a plurality of fuel elements separated from each other forming water gaps therebetween, through which said coolant flows, each of said fuel elements having opposed ends and a peripheral surface extending the length between said opposed ends, said length of each fuel element being parallel to said length of said pressure tube;
• a plurality of spacers for separating said fuel elements from each other;
• a plurality of bearing pads attached to outer fuel elements for providing load bearing to said fuel bundles;
• a plurality of CHF enhancement appendages having a cylindrical shape and being attached to each of certain locations of certain said fuel elements along said length thereof and projecting outwardly from the peripheral surface of said each fuel element into said fuel channel for generating turbulence in said coolant flowing along said length of each of said fuel bundles within said fuel channel downstream of the locations of said CHF enhancement appendages;
• each of said CHF enhancement appendages having a bottom where said CHF enhancement appendage is attached to one of said certain fuel elements, the cross-sectional area of each of said CHF enhancement appendage at said bottom thereof being in a range of 3 mm.sup.2 to 11 mm.sup.2, and the height of said CHF enhancement appendage from said bottom being in a range of 0.6 mm to 2.3 mm, each of said CHF enhancement appendages being attached at said bottom to one of said fuel elements and having no contact with the other fuel elements, one to four appendages being provided in each sub-channel defined by a space surrounded by some of said fuel elements;
• the locations of said CHF enhancement appendages within said fuel bundle being such that the turbulence generated by said CHF enhancement appendages occurs at locations within the fuel bundle where CHF is most likely to occur.