Reactor refueling method

Claim 1

The method of refueling a nuclear reactor having water as a coolant which includes a plurality of normally stationary fuel assemblies supported within a pressure vessel between a lower support structure and an upper support structure, and additionally including a plurality of neutron absorbing control elements adapted for telescoping movement within channels formed between fuel elements in selected fuel assemblies, which method comprises: increasing the amount of homogeneously dispersed neutron absorbing material in the coolant in said pressure vessel to a level sufficient to control the fissionable core with the control elements withdrawn; withdrawing the control elements from their respective channels into the upper structure; retaining the control elements within the upper structure; removing the upper structure with the control elements remaining therein from said pressure vessel whereby the fuel assemblies are exposed, and selectively removing and replacing fuel assemblies.

Claim 2

The method of refueling a nuclear reactor having water as a coolant which includes a plurality of normally stationary fuel assemblies supported within a pressure vessel between a lower support structure and an upper support structure, and additionally including a plurality of neutron absorbing control elements adapted for telescoping movement within channels formed between fuel elements in selected fuel assemblies, which method comprises: increasing the amount of homogeneously dispersed neutron absorbing material in the coolant in said pressure vessel to a level sufficient to control the fissionable core with the control elements withdrawn; withdrawing the control elements from their respective channels into the upper structure; retaining the control elements within the upper structure; removing the upper structure with the control elements remaining therein from said pressure vessel whereby the fuel assemblies are exposed, and selectively removing and replacing fuel assemblies.

Claim 4

The method of refueling a nuclear reactor which includes a plurality of normally stationary fuel assemblies supported within a pressure vessel between a lower support structure and an upper support structure, and additionally including a plurality of neutron absorbing control elements adapted for telescoping movement within channels formed between fuel elements in selected fuel assemblies, said control elements being arranged to be moved by mechanisms located above a head mounted on the pressure vessel, which method comprises: increasing the amount of homogeneously dispersed neutron absorbing material in the coolant to a level sufficient to control the fissionable core with the control elements withdrawn; removing the reactor head and associated mechanisms which adjust the position of control elements in the core while retaining the control elements in the core; withdrawing the control elements from their respective channels into the upper support structure; removing the upper support structure with the control elements remaining therein to thereby expose the fuel assemblies; selectively removing and replacing fuel assemblies; and repeating the above described steps in reverse order to place the reactor in an operative condition.

Claim 5

The method of refueling a nuclear reactor which includes a plurality of normally stationary fuel assemblies supported within a pressure vessel between a lower support structure and an upper support structure, and additionally including a plurality of neutron absorbing control elements adapted for telescoping movement within channels formed between fuel elements in selected fuel assemblies, said control elements being arranged to be moved by mechanisms located above a head mounted on the pressure vessel, which method comprises: increasing the amount of homogeneously dispersed neutron absorbing material in the coolant to a level sufficient to control the fissionable core with the control elements withdrawn; removing the reactor head and associated mechanisms which adjust the position of control elements in the core while retaining the control elements in the core; withdrawing the control elements from their respective channels into the upper support structure; removing the upper support structure with the control elements remaining therein to thereby expose the fuel assemblies; selectively removing and replacing fuel assemblies; and repeating the above described steps in reverse order to place the reactor in an operative condition.

Claim 6

The method of refueling a nuclear reactor which includes a plurality of normally stationary fuel assemblies supported within a pressure vessel between a lower support structure and an upper support structure, And additionally including a plurality of neutron absorbing control elements adapted for telescoping movement within channels formed between fuel elements in selected fuel assemblies, said control elements being arranged to be moved by mechanisms located above a head mounted on the pressure vessel which method comprises: increasing the amount of homogeneously dispersed neutron absorbing material in the coolant to a level sufficient to control the fissionable core with the control elements withdrawn; removing the reactor head and associated mechanisms which adjust the position of control elements in the core while retaining the control elements in the core; attaching a control element removal tool including a cylinder on the upper support structure; withdrawing the control elements from their respective channels into the upper support structure and retaining them therein; removing the cylinder, control elements and the upper support structure as a unit to thereby expose the fuel assemblies; selectively removing and replacing fuel assemblies and repeating the above described steps in reverse order to place the reactor in an operative condition.

Claim 7

The method of refueling a nuclear reactor which includes a plurality of normally stationary fuel assemblies supported within a pressure vessel between a lower support structure and an upper support structure, And additionally including a plurality of neutron absorbing control elements adapted for telescoping movement within channels formed between fuel elements in selected fuel assemblies, said control elements being arranged to be moved by mechanisms located above a head mounted on the pressure vessel which method comprises: increasing the amount of homogeneously dispersed neutron absorbing material in the coolant to a level sufficient to control the fissionable core with the control elements withdrawn; removing the reactor head and associated mechanisms which adjust the position of control elements in the core while retaining the control elements in the core; attaching a control element removal tool including a cylinder on the upper support structure; withdrawing the control elements from their respective channels into the upper support structure and retaining them therein; removing the cylinder, control elements and the upper support structure as a unit to thereby expose the fuel assemblies; selectively removing and replacing fuel assemblies and repeating the above described steps in reverse order to place the reactor in an operative condition.