Patent Number: 052308588
Section: claims

1. In a fuel bundle for boiling water nuclear reactor, said fuel bundle including a matrix of upstanding fuel rods for undergoing nuclear reaction and generating steam, a lower tie plate for supporting the matrix of fuel rods and admitting liquid water moderator to the fuel bundle from the lower portion of said fuel bundle, an upper tie plate for fastening to at least some of the fuel rods and permitting the outflow of liquid and vapor water moderator from the upper portion of said fuel bundle, a channel surrounding said upper and lower tie plates and said fuel rods therebetween for confining moderator flow between said tie plates and around said fuel rods, and a plurality of vertically spaced apart fuel rod spacers, each said spacer surrounding each said fuel rod at the particular elevation of said spacer for maintaining said fuel rods in side-by-side relation, and a water rod for installation to said fuel bundle for supplying liquid moderator to the upper two phase region of said fuel bundle, the improvement to said water rod comprising: said water rod having a first upper compartment, and a second lower compartment, said upper compartment isolated from said lower compartment;  said first upper compartment defining an open, upwardly exposed end for receiving and maintaining water in said upper water rod compartment during the power generating operation of said fuel bundle will fill with liquid by gravity flow from above;  means communicated to the bottom portion of said lower compartment for receiving water from said lower portion of said fuel bundle; and,  means communicated to the upper portion of said lower compartment for discharging water to the interior of said fuel bundle below the upper most spacer of said fuel bundle whereby discharge to said fuel bundle occurs in said upper two phase region of said bundle.  a matrix of upstanding fuel rods for undergoing nuclear reaction and generating steam;  a lower tie plate for supporting the matrix of fuel rods and admitting liquid water moderator tot eh fuel bundle from the lower portion of said fuel bundle;  an upper tie plate for fastening to at least some of the fuel rods and permitting the outflow of liquid and vapor water moderator from the upper portion of said fuel bundle;  a channel surrounding said upper and lower tie plates and said fuel rods therebetween for confining moderator flow between said tie plates and around said fuel rods;  a plurality of vertically spaced apart fuel rod spacers, each said spacer surrounding each said fuel rod at the particular elevation of said spacer for maintaining said fuel rods in side-by-side relation;  a water rod for installation to said fuel bundle for supplying liquid moderator to the upper two phase region of said fuel bundle;  a first upper compartment in said water rod, said first upper compartment defining an open, upwardly exposed end for receiving and maintaining water in said upper water rod compartment during the power generating operation of said fuel bundle;  a second lower compartment in said water rod, said water rod has said upper compartment isolated from said lower compartment;  means communicated to the bottom portion of said lower compartment for receiving water from said lower portion of said fuel bundle; and,  means communicated to the upper portion of said lower compartment for discharging water to the interior of said fuel bundle below the upper most spacer of said fuel bundle whereby discharge to said bundle occurs in said upper two phase region of said bundle.  a matrix of upstanding fuel rods for undergoing nuclear reaction and generating steam;  a lower tie plate for supporting the matrix of fuel rods and admitting liquid water moderator to teh fuel bundle from the lower portion of said fuel bundle;  an upper tie plate for fastening to at least some of the fuel rods and permitting the outflow of liquid and vapor water moderator from the upper portion of said fuel bundle;  a channel surrounding said upper and lower tie plates and said fuel rods therebetween for confining moderator flow between said tie plates and around said fuel rods;  a plurality of vertically spaced apart fuel rod spacers, each said spacer surrounding each said fuel rod at the particular elevation of said spacer for maintaining said fuel rods in side-by-side relation;  a water rod for installation to said fuel bundle for supplying liquid moderator to the upper two phase region of said fuel bundle; a process of supplying said water rod with liquid moderator comprising the steps of:  providing a first upper compartment in said water rod;  opening said first upper compartment to receive and maintain water in said upper water rod compartment during the power generating operation of said fuel bundle;  providing a second lower compartment in said water rod, said water rod having said upper compartment isolated from said lower compartment;  communicating in flowing water to the bottom portion of said lower compartment for receiving water from said lower portion of said fuel bundle; and,  discharging from the upper portion of said lower compartment to the interior of said fuel bundle below the upper most spacer whereby water discharge to said fuel bundle occurs in said upper two phase region of said bundle. 2. The fuel bundle of claim 1 and wherein said means communicated to the upper portion of said lower compartment discharges water to the interior of the fuel bundle occurs between the first and second spacer. 3. The fuel bundle of claim 1 and wherein said means communicated to the upper portion of said lower compartment discharges water to the interior of the fuel bundle occurs between the second and third spacer. 4. The fuel bundle of claim 1 and wherein said fuel bundle has one large central water rod. 5. A fuel bundle for boiling water nuclear reactor, said fuel bundle comprising: 6. In a fuel bundle for a boiling water nuclear reactor, said fuel bundle comprising: 7. The process of claim 6 and wherein said discharging water to the interior of the fuel bundle occurs between the first and second spacer. 8. The process of claim 6 and wherein said discharging water to the interior of the fuel bundle occurs between the second and third spacer.