RELAP5-3D Architectural Developments in 2004

Currently, RELAP5 is undergoing a transformation that will replace much of its coding with equivalent structured Fortran 90 coding. Four efforts are underway to modernize the code architecture of RELAP5-3D. These are parallelization, vectorization, code restructuring, and conversion to Fortran 90. The first two improve code run speed via on computer platforms of certain architectures. These code modifications have little effect on normal code performance on non-vector and non-parallel computers because they are mostly done with compiler directives. The third and fourth efforts involve considerable rewriting of the source code. The third code improvement effort addresses code readability and maintainability. These are being greatly enhanced by application of a Fortran code-restructuring tool. The fourth effort is conversion to Fortran 90. The bulk of the coding is being rewritten in Fortran 90. This is a ground up reworking of the coding that begins with completely reorganizing the underlying database and continues with the source code. It will reach every part of RELAP5-3D. Each of these efforts is discussed in detail in a different section. Section 1 relates background information. Section 2 covers the parallelization effort. Section 3 covers the efforts to vectorize the code. Section 4 covers the code restructuring. Section 5 covers the Fortran 90 effort. Outline Background: longevity, maintenance & development, reliability, speed Parallelization: KAI to OpenMP, previous work & current, domain decomposition, done. Vectorization: Speed - Fed init, vectors in PCs, INL Cray SV1, R5 Phant, EXV, results. Code Restructuring: Reason to restructure, study of restruct, For Study: what it does, Fortran 90: Modernization