Patent Number: 
Section: claims

1. A method of calculating rod peak criteria, comprising:calculating pin nodal exposures and pin nodal powers of a plurality of rods in a plurality of fuel assemblies using a pre-defined process;calculating, for each of the plurality of rods, a rod average exposure using a weight factor associated with the rod, each weight factor based on one of a nodal weight and a pin weight of the rod;calculating a plurality of rod average powers of the plurality of rods in all of the fuel assemblies of the plurality of fuel assemblies;inputting a rod average exposure limit and a power limit for an alternative source term;developing core maps from the plurality of calculated rod average exposures and powers using the inputted rod average exposure limit and the inputted power limit;outputting the developed maps; andediting the developed maps. 2. The method of claim 1, wherein the core maps are two-dimensional (2D). 3. The method of claim 2, wherein determining the rod average exposures develops the 2D core maps. 4. The method of claim 2, wherein determining the rod average power (kW/ft) develops the 2D core maps. 5. The method of claim 2, wherein determining a peak rod average exposure develops the 2D core maps. 6. The method of claim 2, wherein determining a peak rod average power (kW/ft) develops the 2D core maps. 7. The method of claim 2, wherein a ratio of a peak rod average power (kW/ft) to a limit develops the 2D core maps. 8. The method of claim 1, wherein the calculation of the rod average exposures and the rod average powers are in a selected fuel assembly. 9. A method of calculating rod peak criteria for fuel rods in a nuclear reactor, comprising:calculating pin nodal exposures and pin nodal powers;calculating rod average exposures and rod average powers in each fuel assembly based on the calculated pin nodal exposures and pin nodal powers and using a weight factor based on one of a nodal weight and a pin weight;inputting a rod average exposure limit and a power limit for an alternative source term;developing two dimensional (2D) core maps from the calculated rod average exposures and powers based on the inputted rod average exposure limit and the inputted power limit;outputting the developed 2D maps; andediting the outputted generation 2D maps. 10. The method of claim 9, wherein the calculation of the rod average exposures and powers are performed by calculating pin nodal exposures in each axial fuel node. 11. The method of claim 9, wherein the calculation of the rod average exposures and powers (kW/ft) are performed by calculating pin nodal powers in each axial fuel node. 12. The method of claim 9, wherein determining the rod average exposure develops the 2D core maps. 13. The method of claim 9, wherein determining the rod average power (kW/ft) develops the 2D core maps. 14. The method of claim 9, wherein determining a peak rod average exposure develops the 2D core maps. 15. The method of claim 9, wherein determining a peak rod average power (kW/ft) develops the 2D core maps. 16. The method of claim 9, wherein a ratio of a peak rod average power (kW/ft) to a limit develops the 2D core maps. 17. The method of claim 9, wherein the calculation of the rod average exposures and the rod average powers are in a selected fuel assembly. 18. The method of claim 1, wherein calculating the pin nodal exposures and the pin nodal powers of the plurality of rods in the plurality of fuel assemblies using a pre-defined process includes partitioning the plurality of rods into a number of nodes and calculating a pin nodal exposure and a pin nodal power for each node. 19. The method of claim 18, further comprising:calculating weight factor for each node of the number of nodes, wherein calculating, for each of the plurality of rods, a rod average exposure using a weight factor associated with the rod includes multiplying each of the calculated pin nodal exposures with their respective calculated weight factor, summing the products of the calculated pin nodal exposures with their respective weight factors to form a first sum and dividing the first sum by a total weight of the rod.