1. User Group Meeting | 2016 | Boise, Idaho, USA
FRAPCON/FRAPTRAN Users Group Meeting: Recent Code Release and Future Plans
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Ken Geelhood
Pacific Northwest National Laboratory
Richland, WA
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

2. User Group Meeting | 2016 | Boise, Idaho, USA
Summary
Current code versions
Summary of Changes
FRAPCON-4.0
FRAPTRAN-2.0
Upcoming Changes
Changes beyond these versions
Next Code Release
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

3. User Group Meeting | 2016 | Boise, Idaho, USA
Current Code Versions
FRAPCON-4.0
FRAPCON-4.0 patch 1
FRAPTRAN-2.0
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

4. Summary of Changes: FRAPCON-4.0
Extensive work has been done to modernize the FORTRAN language used for FRAPCON
Commons have been eliminated and variables are stored in modules for use in other subroutines
Code changed from fixed format to free format
More modern syntax has been employed for logic tests. Eg <, <=, ==, >=, > rather than lt, le, eq, ge, gt
All subroutines have been grouped into modules according to their function
Go to statements and if, then, else constructs have been replaced with CASE statements wherever possible
Need for compiler options has been eliminated
Double precision explicitly stated on all variables
All variables explicitly declared
Variables are dynamically dimensioned to the size of the current problem
No restriction on # of axial (na) or radial (nr, ngasr) nodes, no limit to the # of timesteps (im) or axial power profiles (up to im)
Code will be distributed with makefile for compiling on LINUX and OSX
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

5. Summary of Changes: FRAPCON-4.0 (cont.)
Code predictions from FRAPCON-4.0 are nearly identical to FRAPCON-3.5
Several bugs have been removed and models have been improved
Update to plenum temperature model
Update to gas properties
Several new capabilities have been added
Added the ANS-5.4 (2011) Standard Fission Product Release Model
“EM” options have been removed
Ability to model spent fuel storage using the DATING creep models added
Ability to use the ANS-5.1 decay heat model to calculate heating after shutdown added
Ability to specify axial coolant conditions (Temp, Press) was added
Various “Developer” options have been added to allow the user to change various model parameters for sensitivity study
These options have the potential to change the FRAPCON results such that the outputs are no longer validated
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

6. Summary of Changes: FRAPCON-4.0 Patch 1
Fix error in terminating oxidation calculation (calcoxide)
Intel 2015 Compliance
Fix error with specified cladding temperatures
Compiles with GNU FORTRAN
Replaced error function to use FORTRAN error function
Removed Scratch file
Added ability to output B10 concentration
Added ability to input ZrB2 thickness in SI units
Fix error in spring unit conversion
Corrected error in ANS model
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

7. Summary of Changes: FRAPTRAN-2.0
Extensive work has been done to modernize the FORTRAN language used for FRAPTRAN
Commons have been eliminated and variables are stored in modules for use in other subroutines
Code changed from fixed format to free format
More modern syntax has been employed for logic tests. Eg <, <=, ==, >=, > rather than lt, le, eq, ge, gt
All subroutines have been grouped into modules according to their function
Go to statements and if, then, else constructs have been replaced with CASE statements wherever possible
Need for compiler options has been eliminated
Double precision explicitly stated on all variables
All variables explicitly declared
Variables are dynamically dimensioned to the size of the current problem
No restriction on # of axial (na) or radial (nr, ngasr) nodes, no limit to the # of timesteps (im) or axial power profiles (up to im)
Code will be distributed with makefile for compiling on LINUX and OSX
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

8. Summary of Changes: FRAPTRAN-2.0 (cont.)
Code predictions from FRAPTRAN-2.0 are nearly identical to FRAPTRAN 1.5
Several bugs have been removed and models have been improved
Update to void volume calculations
Changes to transient thermal solution proposed by Lars Jernkvist from Quantum Technologies was implements
Several new capabilities have been added
Water properties file not necessary
Option to select relocation model was added
Improved ability to link to TH codes
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

9. Summary of Changes: FRAPCON-4.0 and FRAPTRAN-2.0
Updates have been made to the Excel Auto Input Generator
All input variables are available to the user through this file
Tabs with required input are shown in red
Tabs with optional input for exercising various code options are shown in blue
Standard dimensions from various assembly designs are available to pre-populate input
Generator has been made dynamic (can continue as needed for axial variations, power history, coolant conditions, etc.)
Updates have been made to the Excel Plot File
Ability to plot an axial plot at a various time steps has been added to “1D data” tab
Surface plots in “2D data” tab improved
Ability added to plot axial and radial gas information added (nplot=2) e.g. gas in grains, grain boundary gas, produced gas
Ability to switch between British/SI units
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

10. Summary of Changes: FRAPCON-4.0 and FRAPTRAN-2.0 (cont.)
Updates have been made to the QA procedures
GitHub used for version control of source code
V&V cases established
Unit test cases. Separate driver program run subroutines to verify their performance relative to hand calculations
Verification test cases. Database of test cases is being established to test all code functionality
Validation test cases. Integral Assessment cases used to validate code predictions
Code change tracking tool implemented to assign, track, and document new code developments
FRAPVALID auto validation tool from IRSN implemented to assess the impact of new code modifications
Dakota scripts written for FRAPCON and FRAPTRAN uncertainty analyses
Modernization of assessment cases
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

11. Upcoming Changes (underway)
FRAPCON General Improvements and Reliability
Automate time step size reduction in creep subroutine to avoid crashes
Retune FRAPFGR model to make this model the primary FGR model and add output of grain boundary gas and high burnup rim structure.
FRAPTRAN General Improvements and Reliability
Investigate and fix problems with code crashes and eliminate unnecessary error messages
Investigate and fix as appropriate the following potential issues in the code:
Adjust fast neutron flux and burnup for gadolinia rods
Investigate potential inconsistencies between thermal and mechanical gaps
Investigate passage of rod internal pressure from FRAPCON to FRAPTRAN
Add fuel swelling due to fission gas swelling in FRAPTRAN
Fix problem with calculating DT on OD and ID of cladding in FRAPTRAN
Add ability to input CRUD thickness and calculate DT in FRAPTRAN
Develop hydride reorientation model
Modernization of assessment input cases to match current code capability
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

12. Changes Beyond These Versions
NRC and PNNL are developing a 5 year plan for FRAPCON and FRAPTRAN. Some items for this plan include:
Better integration with SNAP
Expansion of the integral assessment case inventory including most or all Halden tests
Improvements in ballooning models in axial direction, to support eventual predictions of fuel dispersal, as well as axial stack relocation, and inclusion of grid spacers
Look into vendor developments and ensure that NRC codes are following the trends, such as pellet additives, new cladding types
Ensure that the NRC codes are providing reasonable predictions for SMR fuel designs and make necessary changes
Perform a targeted literature review to keep track of domestic and international developments in licensed fuel performance codes, to stay at the state-of-the-art
Integration or coupling with TRACE and PARCS
FRAPTRAN dynamic time stepping based on back-stepping and normalized change metric, as well as output to the console to inform the user on status of calculation
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA

13. User Group Meeting | 2016 | Boise, Idaho, USA
Next Code Release
Plan to release FRAPCON-4.1 and FRAPTRAN-2.1 by September 2018
November 13, 2018
User Group Meeting | 2016 | Boise, Idaho, USA