Transcript STREAMLINING OF RELAP5-3D RELAP5 International User Seminar Nov 4-6, 2007

STREAMLINING OF
RELAP5-3D
Dr. George L Mesina (INL)
Joshua Hykes (PSU), Riley Cumberland (UMR)
Donna Guillen (INL)
RELAP5 International User Seminar
Nov 4-6, 2007
INL/CON-07-13373
Outline
• Motivation and overview of Streamlining
• History of RELAP5-3D developments
– Impact of these developments
• Streamlining Algorithm
• Valuation of Streamlining
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Motivation for Streamlining
• Something you do BEFORE verification or validation
• Improves source code and shortens time for V&V
Source code
Validation
Verification
Improved code
Code implements
what documents say.
DA
Code calculations
are correct.
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Streamlining for Legacy Codes
• Legacy codes
– Successful applications, in active use, developed
over the course of many years or even decades.
• Some examples
– RELAP5, TRAC/TRACE, CATHARE, RETRAN,
COBRA, CONTAIN, MELCOR, MCNP
– Model (portion or whole) nuclear plant
– In use for over a decade
– Most still undergoing development
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Some Legacy Code Common Issues
• Extension of applicability beyond original design
• Many adaptations for operating systems/compilers
• Optimizations for computer architectures
• New features with very different data structures
– Imported/subsumed “library” subprograms
• Numerics improvements often complicate coding
• Multiple different programming styles
• Use of conditional coding
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Legacy Code Common Difficulties
• Difficult to read and understand
– Especially for new/next-generation developers
• Difficult to maintain and develop
– Maintain
• Adapt to computing industry changes
• Solve reported problems and issue fixes
– Develop - add features needed by code users
• These difficulties can impact co$t and $chedule
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Purpose of Streamlining
• Increase code readability and understandability
• Reduce time and cost of maintenance and
development
• This will increase code/team longevity
– Adapt to computer industry continual changes
– Add new/young programmers to team
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RELAP5-3D Development History
• At its inception RELAP5 was designed to analyze
large break LOCA in a PWR
Version
Capability Added
Affects
MOD1
Small Break LOCA
physics
code length
BWR
physics
code length
Semi-implicit time step
numerics
complexity
6 governing equations
numerics
*
Nearly-implicit time step
numerics
complexity
Alternate fluids
physics
conditional
MOD2
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RELAP5-3D Development History
MOD3
MOD3.2
Textbook correlations
physics
numerics
Offtake & CCFL models
physics
length
vectorize
architecture
complexity
NESTLE 3D kinetics
physics
conditional
3D Hydrodynamics
physics
conditional
multi-D heat transfer
physics
conditional
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RELAP5-3D History, DOE funded
Realtime
(simulators)
3D
Parallel processing
architecture
complexity
Vector-parallel solver
numerics
code length
SIMPORT (GUI) hook
architecture
complexity
PVM coupling
architecture
complexity
RGUI (3D visualization)
architecture
code length
Models, components, fluids
physics
complex, “
• Much more in 3D including: SCDAP, proprietary
coding, optimizations, architectural upgrades, etc.
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Specific Impact of Developments
• Many sections of conditional code
• Too many GO TO statements in some subprograms
• Many subprograms too large (up to 5000 lines long)
• Baggage: obsolete language constructs, machinespecific code, unused sections of code
• Many patches (bug fixes, machine adaptations, etc.)
• Styles of 2 dozen programmers
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Streamlining Method
• Rework database and source code
– Database streamlining presented elsewhere
• Source code streamlining
– Create and apply consistent programming style
rules
– Transform code into structured programming
– Eliminate unused and obsolete sections of code
– Simplify complex subprograms
– Replace programming “tricks” (workarounds that
overcome language limitations)
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Streamlining Approach
•
•
Apply FOR_STRUCT commercial restructuring tool
to eliminate GO TOs & apply style rules
Cannot be done directly
•
– No conditional or non-ANSI standard code
(Fortran 77) can be restructured
Solution: Preprocess – transform – post-process
– Replace or comment out non-standard code
– Preprocessor handles conditional code
– Afterwards restore non-standard & conditional
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Pre-compiling Conditional Code
•
Example of conditional code: Proprietary Code
– Either proprietary code or generic code used
– Sections of proprietary code and generic code
are marked by “pre-compiler directives”
• Mark at beginning indicates conditional-kind
• Another indicates end of section
– Pre-compiler removes all sections of one
conditional-kind but leaves the alternate
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High Level Streamlining Approach
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Some Difficulties and Workarounds
• Combinations of different kinds of conditional code.
– N different kinds => 2N combinations
• Solution: Restructure and carefully recombine
– Use minimal set of combinations << 2N.
• If > 500 lines of source, does not fully restructure
• Solution: Use FOR_STRUCT output as new input
– Iterate three times
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Automated Streamlining Algorithm
• Marker: a comment placed where a conditional
section of code (and directives) must be restored
• Def file: specifies a combination of conditional code
• Test and debug
• Apply process one subprogram at a time
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Manual Streamlining Necessary
• Some conditional code directives get misplaced by
restructuring (automated algorithm).
– Reposition manually after restoration
OR
– Manually create internal subroutine from section
of conditional code, including directives.
• Some subprograms are harder to read/understand
after restructuring
– Manually rewrite
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Valuation of Streamlining
• Readability measure: reduction of GOTO statements
and labels.
– Tangle logic flow paths. Obscure base algorithm.
Go to statements
Sub w/ 0 GO TOs
Before
After
Ratio
255
386
0.66
9
1
9
6707
3977
1.69
Computed GO TOs
100
7
14.29
Backward GO TOs
822
125
6.32
Sub w/ 100+ GO TOs
Total GO TOs
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Valuation of Streamlining
Reduction in Labels
100%
90%
80%
70%
60%
50%
40%
A f t er
30%
B ef or e
20%
10%
0%
0 labels
100 or
m ore
labels
Total
labels
Labels
Nonof
form at
form ats labels
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Valuation of Streamlining
• Improvements from streamlining
– Uniform style rules applied
– Measurable reduction in GO TO statements and
labels
– No dead code
– Use of internal subroutines
• These result in logic flow paths being easier to trace
– Often reduce the number of logic flow paths
• Enhance readability and understandability
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Valuation of Streamlining
• Streamlining time (relap & envrl): About 3/4 year
– 28 weeks by summer interns
– 12 weeks (initial work and mentor supervision)
• Effect on size: slightly fewer (0.5%) lines of code
– No dead code, shorter rewritten sections
• Effect on code portability
– Fewer ANSI-standard obsolescent constructs
• Effect on code calculations and runtime
– None
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Conclusion
• Streamlining is a process for legacy codes.
• It improves code readability and understandability
in measurable ways
– This can help reduce the time and cost of code
maintenance and development
– Should be done before V&V, DA
• It has no effect on code calculations or run time
• It costs comparatively little to enact
05-GA