Material Property Correlations: Comparisons between FRAPCON-3.4, FRAPTRAN 1.4, and MATPRO

The U.S. Nuclear Regulatory Commission (NRC) uses the computer codes FRAPCON-3 and FRAPTRAN to model steady state and transient fuel behavior, respectively, in regulatory analysis. In order to effectively model fuel behavior, material property correlations must be used for a wide range of operating conditions (e.g. temperature and burnup). In this sense, a 'material property' is a physical characteristic of the material whose quantitative value is necessary in the analysis process. Further, the property may be used to compare the benefits of one material versus another. Generally speaking, the material properties of interest in regulatory analysis of nuclear fuel behavior are mechanical or thermodynamic in nature. The issue of what is and is not a 'material property' will never be universally resolved. In this report, properties such as thermal conductivity are included. Other characteristics of the material (e.g. fission gas release) are considered 'models' rather than properties, and are discussed elsewhere. Still others (e.g., neutron absorption cross-section) are simply not required in this specific analysis. The material property correlations for the FRAPCON-3 and FRAPTRAN computer codes were documented in NUREG/CR-6534 and NUREG/CR-6739, respectively. Some of these have been modified or updated since the original code documentation was published. The primary purpose of this report is to consolidate the current material property correlations used in FRAPCON-3 and FRAPTRAN into a single document. Material property correlations for oxide fuels, including uranium dioxide (UO2) and mixed oxide (MOX) fuels, are described in Section 2. Throughout this document, the term MOX will be used to describe fuels that are blends of uranium and plutonium oxides, (U,Pu)O2. The properties for uranium dioxide with other additives (e.g., gadolinia) are also discussed. Material property correlations for cladding materials and gases are described in Sections 3 and 4, respectively. In addition to describing the material property correlations used in the subroutines of FRAPCON-3 and FRAPTRAN, this report also provides a variety of comparisons between material property correlations and data. Although they are frequently identical, comparisons are made between the material property correlations used in the FRAPCON-3 and FRAPTRAN codes. Comparisons are also made between the material property correlations used in MATPRO, a compilation of fuel and cladding material property correlations with an extensive history of used with various fuel performance and severe accident codes. For a number of reasons, consistency between the material property correlations in FRAPCON-3, FRAPTRAN, and MATPRO has never been complete. However, the current versions of FRAPCON-3 and FRAPTRAN use a relatively consistent set of correlations for the properties that are used by both codes. The material property correlations in the most recent version of MATPRO are documented in Volume 4 of NUREG/CR-6150. In addition to comparison of the various correlations, correlation-to-data comparisons are also made with FRAPCON-3, FRAPTRAN, and MATPRO. All comparisons made in this report are based on the material property correlations used in the most recent version of the FRAPCON-3 and FRAPTRAN codes, FRAPCON-3.4 and FRAPTRAN 1.4. The source code for each material property correlation discussed will be provided for FRAPCON-3.4 and FRAPTRAN 1.4 (see appendix) as well as a range of applicability and an estimate of uncertainty where possible

Sensitivity Analysis of Hardwired Parameters in GALE Codes

The U.S. Nuclear Regulatory Commission asked Pacific Northwest National Laboratory to provide a data-gathering plan for updating the hardwired data tables and parameters of the Gaseous and Liquid Effluents (GALE) codes to reflect current nuclear reactor performance. This would enable the GALE codes to make more accurate predictions about the normal radioactive release source term applicable to currently operating reactors and to the cohort of reactors planned for construction in the next few years. A sensitivity analysis was conducted to define the importance of hardwired parameters in terms of each parameter’s effect on the emission rate of the nuclides that are most important in computing potential exposures. The results of this study were used to compile a list of parameters that should be updated based on the sensitivity of these parameters to outputs of interest

FRAPCON analysis of cladding performance during dry storage operations

There is an increasing need in the United States and around the world to move used nuclear fuel from wet storage in fuel pools to dry storage in casks stored at independent spent fuel storage installations or interim storage sites. Under normal conditions, the Nuclear Regulatory Commission limits cladding temperature to 400°C for high-burnup (>45 GWd/mtU) fuel, with higher temperatures allowed for low-burnup fuel. An analysis was conducted with FRAPCON-4.0 on three modern fuel designs with three representative used nuclear fuel storage temperature profiles that peaked at 400°C. Results were representative of the majority of US light water reactor fuel. They conservatively showed that hoop stress remains below 90 MPa at the licensing temperature limit. Results also show that the limiting case for hoop stress may not be at the highest rod internal pressure in all cases but will be related to the axial temperature and oxidation profiles of the rods at the end of life and in storage. Keywords: Dry Storage, FRAPCON, Fuel Performance, Radial Hydride Reorientation, Vacuum Dryin

Material Property Correlations: Comparisons between FRAPCON-3.4, FRAPTRAN 1.4, and MATPRO

The U.S. Nuclear Regulatory Commission (NRC) uses the computer codes FRAPCON-3 and FRAPTRAN to model steady state and transient fuel behavior, respectively, in regulatory analysis. In order to effectively model fuel behavior, material property correlations must be used for a wide range of operating conditions (e.g. temperature and burnup). In this sense, a 'material property' is a physical characteristic of the material whose quantitative value is necessary in the analysis process. Further, the property may be used to compare the benefits of one material versus another. Generally speaking, the material properties of interest in regulatory analysis of nuclear fuel behavior are mechanical or thermodynamic in nature. The issue of what is and is not a 'material property' will never be universally resolved. In this report, properties such as thermal conductivity are included. Other characteristics of the material (e.g. fission gas release) are considered 'models' rather than properties, and are discussed elsewhere. Still others (e.g., neutron absorption cross-section) are simply not required in this specific analysis. The material property correlations for the FRAPCON-3 and FRAPTRAN computer codes were documented in NUREG/CR-6534 and NUREG/CR-6739, respectively. Some of these have been modified or updated since the original code documentation was published. The primary purpose of this report is to consolidate the current material property correlations used in FRAPCON-3 and FRAPTRAN into a single document. Material property correlations for oxide fuels, including uranium dioxide (UO2) and mixed oxide (MOX) fuels, are described in Section 2. Throughout this document, the term MOX will be used to describe fuels that are blends of uranium and plutonium oxides, (U,Pu)O2. The properties for uranium dioxide with other additives (e.g., gadolinia) are also discussed. Material property correlations for cladding materials and gases are described in Sections 3 and 4, respectively. In addition to describing the material property correlations used in the subroutines of FRAPCON-3 and FRAPTRAN, this report also provides a variety of comparisons between material property correlations and data. Although they are frequently identical, comparisons are made between the material property correlations used in the FRAPCON-3 and FRAPTRAN codes. Comparisons are also made between the material property correlations used in MATPRO, a compilation of fuel and cladding material property correlations with an extensive history of used with various fuel performance and severe accident codes. For a number of reasons, consistency between the material property correlations in FRAPCON-3, FRAPTRAN, and MATPRO has never been complete. However, the current versions of FRAPCON-3 and FRAPTRAN use a relatively consistent set of correlations for the properties that are used by both codes. The material property correlations in the most recent version of MATPRO are documented in Volume 4 of NUREG/CR-6150. In addition to comparison of the various correlations, correlation-to-data comparisons are also made with FRAPCON-3, FRAPTRAN, and MATPRO. All comparisons made in this report are based on the material property correlations used in the most recent version of the FRAPCON-3 and FRAPTRAN codes, FRAPCON-3.4 and FRAPTRAN 1.4. The source code for each material property correlation discussed will be provided for FRAPCON-3.4 and FRAPTRAN 1.4 (see appendix) as well as a range of applicability and an estimate of uncertainty where possible

PNNL Stress/Strain Correlation for Zircaloy

Pacific Northwest National Laboratory (PNNL) was tasked with incorporating cladding mechanical property data into the Nuclear Regulatory Commission (NRC) fuel codes, FRAPCON-31 and FRAPTRAN2, by the NRC Office of Nuclear Reactor Research. The objective of that task was to create a mechanical model that can calculate true stress, true strain, and the possible failure of the fuel rod cladding based on uniaxial test data

Predictive Bias and Sensitivity in NRC Fuel Performance Codes

The latest versions of the fuel performance codes, FRAPCON-3 and FRAPTRAN were examined to determine if the codes are intrinsically conservative. Each individual model and type of code prediction was examined and compared to the data that was used to develop the model. In addition, a brief literature search was performed to determine if more recent data have become available since the original model development for model comparison