Granted Patent B2

US 10,014,083 · App. 13/461,821 · Granted Jul 3, 2018

Abstract

Claims (26)

1. A method of refueling a nuclear reactor comprising a reactor vessel having an open upper end with a flange, the reactor vessel housing a core including a plurality of fuel assemblies and an upper internals structure supported above the core, and a head with a mating flange for sealing the open upper end of the reactor vessel; the method comprising the steps of:

removing the reactor vessel head;

placing the reactor vessel head in a first storage location outside of a path above the reactor vessel;

lifting the upper internals structure out of the reactor vessel to a second storage location outside of the path above the reactor vessel;

detachably installing a cylindrical tank having an open lower end and an open upper end, on the reactor vessel flange so that the reactor vessel flange substantially supports the cylindrical tank;

detachably sealing the lower end of the cylindrical tank to the reactor vessel and a penetration on a side of the cylindrical tank to a refueling canal that is connected to a spent fuel pool;

raising a level of reactor coolant within the reactor vessel to at least partially fill the cylindrical tank substantially to a level equal to a level of a coolant within the spent fuel pool;

opening the refueling canal; and

employing a refueling machine at least in part supported above the cylindrical tank, to transfer a number of the fuel assemblies within the core, through the penetration and the refueling canal to a storage location in the spent fuel pool.

2. The method of claim 1 wherein the step of lifting the upper internals structure includes the steps of:

supporting a radiation shield in the form of an shielded bell with an open lower end, above the open upper end of the reactor vessel;

lowering the radiation shield substantially to the reactor vessel flange over at least a portion of the upper internals structure;

raising the upper internals structure within the radiation shield; and

lifting the radiation shield with the upper internals structure inside to the second storage location.

3. The method of claim 2 including the step of lowering the upper internals structure from the radiation shield to a shielded stand at the second storage location.

4. The method of claim 3 wherein the shielded stand is located in a pool of coolant.

5. The method of claim 2 including the steps of:

drawing air into the radiation shield;

filtering the air before it is exhausted from the radiation shield; and

exhausting the air in the radiation shield after it has been filtered.

6. The method of claim 2 wherein the step of lifting the upper internals structure is accomplished with a reactor building main crane.

7. The method of claim 1 including the step of supporting the refueling machine from the reactor vessel.

8. The method of claim 7 including the step of supporting the refueling machine from the top of the cylindrical tank.

9. The method of claim 7 including the step of indexing the refueling machine off of the reactor flange to locate the fuel assemblies to be removed.

10. The method of claim 1 wherein the step of raising the level of reactor coolant is accomplished with an existing reactor vessel penetration.

11. The method of claim 1 wherein the step of sealing the lower end of the cylindrical tank is sealed to the reactor vessel flange.

Assignments (8)