The invention relates to the use of Dispersion Ceramic Micro-Encapsulated (DCM) nuclear fuel as a meltdown-proof, accident-tolerant fuel to replace uranium dioxide fuel in existing light water reactors (LWRs). The safety qualities of the DCM fuel are obtained by the combination of three strong barriers to fission product release (ceramic coatings around the fuel kernels), highly dense inert ceramic matrix around the coated fuel particles and metallic or ceramic cladding around the fuel pellets.

A nuclear fuel assembly comprising a plurality of control rod guide assemblies. At least one of the control rod guide assemblies includes a guide tube having an axial dimension, the guide tube being supported by the plurality of grids and extending axially between the top nozzle and the bottom nozzle, the guide tube having an upper portion having a first radius and a lower portion having a second radius less than the first radius, and an external dashpot tube disposed around a portion of the lower portion in an area beginning at the bottom grid and extending toward the top nozzle.

A nuclear fuel assembly comprising a plurality of control rod guide assemblies. At least one of the control rod guide assemblies includes a guide tube having an axial dimension, the guide tube being supported by the plurality of grids and extending axially between the top nozzle and the bottom nozzle, the guide tube having an upper portion having a first radius and a lower portion having a second radius less than the first radius, and an external dashpot tube disposed around a portion of the lower portion in an area beginning at the bottom grid and extending toward the top nozzle.

A nuclear fuel assembly comprising a plurality of control rod guide assemblies. At least one of the control rod guide assemblies includes a guide tube having an axial dimension, the guide tube being supported by the plurality of grids and extending axially between the top nozzle and the bottom nozzle, the guide tube having an upper portion having a first radius and a lower portion having a second radius less than the first radius, and an external dashpot tube disposed around a portion of the lower portion in an area beginning at the bottom grid and extending toward the top nozzle.

A nuclear fuel assembly comprising a plurality of control rod guide assemblies. At least one of the control rod guide assemblies includes a guide tube having an axial dimension, the guide tube being supported by the plurality of grids and extending axially between the top nozzle and the bottom nozzle, the guide tube having an upper portion having a first radius and a lower portion having a second radius less than the first radius, and an external dashpot tube disposed around a portion of the lower portion in an area beginning at the bottom grid and extending toward the top nozzle.

Disclosed is a method of predicting, calculating, or analyzing the sintered density of uranium oxide (UO.sub.x) before uranium oxide is added in the pelletizing process during a process of manufacturing nuclear fuel, the method including measuring the chromaticity of ammonium diuranate using a spectrophotometer. The present invention provides a simple and highly reliable method of predicting the sintered density of uranium oxide (UO.sub.x), which overcomes the problem with a conventional technology where the sintered density of uranium oxide (UO.sub.x) can be analyzed only in a pellet state and a subsequent treatment process needs to be performed according to the analysis result.

Disclosed is a method of predicting, calculating, or analyzing the sintered density of uranium oxide (UO.sub.x) before uranium oxide is added in the pelletizing process during a process of manufacturing nuclear fuel, the method including measuring the chromaticity of ammonium diuranate using a spectrophotometer. The present invention provides a simple and highly reliable method of predicting the sintered density of uranium oxide (UO.sub.x), which overcomes the problem with a conventional technology where the sintered density of uranium oxide (UO.sub.x) can be analyzed only in a pellet state and a subsequent treatment process needs to be performed according to the analysis result.

Disclosed is a method of predicting, calculating, or analyzing the sintered density of uranium oxide (UO.sub.x) before uranium oxide is added in the pelletizing process during a process of manufacturing nuclear fuel, the method including measuring the chromaticity of ammonium diuranate using a spectrophotometer. The present invention provides a simple and highly reliable method of predicting the sintered density of uranium oxide (UO.sub.x), which overcomes the problem with a conventional technology where the sintered density of uranium oxide (UO.sub.x) can be analyzed only in a pellet state and a subsequent treatment process needs to be performed according to the analysis result.

Disclosed is a method of predicting, calculating, or analyzing the sintered density of uranium oxide (UO.sub.x) before uranium oxide is added in the pelletizing process during a process of manufacturing nuclear fuel, the method including measuring the chromaticity of ammonium diuranate using a spectrophotometer. The present invention provides a simple and highly reliable method of predicting the sintered density of uranium oxide (UO.sub.x), which overcomes the problem with a conventional technology where the sintered density of uranium oxide (UO.sub.x) can be analyzed only in a pellet state and a subsequent treatment process needs to be performed according to the analysis result.

The invention relates to the use of Dispersion Ceramic Micro-Encapsulated (DCM) nuclear fuel as a meltdown-proof, accident-tolerant fuel to replace uranium dioxide fuel in existing light water reactors (LWRs). The safety qualities of the DCM fuel are obtained by the combination of three strong barriers to fission product release (ceramic coatings around the fuel kernels), highly dense inert ceramic matrix around the coated fuel particles and metallic or ceramic cladding around the fuel pellets.