Patent Number: 
Section: claims

1. A method to assess light water reactor fuel integrity after a given time of operation of the reactor, the method comprising:granting access in a nuclear reactor fuel pool to at least one of a discharged fuel rod and a nuclear fuel assembly, wherein the at least one discharged fuel rod or nuclear fuel assembly experienced a heat flux;determining the heat flux experienced by the at least one fuel rod or nuclear fuel assembly;measuring a thickness of CRUD on the at least one fuel rod or nuclear fuel assembly;measuring a thickness of oxide on the at least one fuel rod or nuclear fuel assembly;determining a maximum possible heat flux for the at least one fuel rod or nuclear fuel assembly for a position of the at least one fuel rod or nuclear fuel assembly in a nuclear reactor on a life of the fuel assembly;determining a maximum possible CRUD deposit for the at least one fuel rod or nuclear fuel assembly in the nuclear reactor;determining a maximum possible oxide thickness for the at least one fuel rod or nuclear fuel assembly in the nuclear reactor;calculating a fuel condition index of the at least one fuel rod or nuclear fuel assembly in a calculation comprising calculating a ratio of the experienced heat flux to the maximum possible heat flux, calculating a ratio of the CRUD measured thickness to the maximum possible CRUD thickness, and calculating a ratio of the measured oxide thickness to the maximum possible oxide thickness;comparing the fuel condition index to an index constant; andremoving the at least one of the fuel rod and the nuclear fuel assembly from operation when the fuel condition index is greater than the index constant. 2. The method according to claim 1, wherein the fuel condition index is calculated as      ∑          (                        OperatingFlux          MaximFlux                +                  OperatingDeposit          MaximDeposit                +                  OperatingOxideThickness                      MaximOxide            ⁢            Thickness                              )        ≤          ⁢  Awhere A is the index constant. 3. The method according to claim 2, wherein the index constant A has a value determined as a function of a size of a safety margin. 4. The method according to claim 2, wherein the index constant A has a value of 3.0 without a safety margin. 5. The method according to claim 1, wherein the calculated fuel condition index divides plants according to high, medium and low risk fuel. 6. The method according to claim 1, wherein the light water reactor is one of a boiling water reactor and a pressurized water reactor.