Notice of Intent to Noncompetitively Upgrade ACS SASSI

The NRC intends to noncompetitively procure upgrade of ACS SASSI for the performance period of 02/27/2019 - 04/30/2020 to Ghiocel Predictive Technologies Inc.

The SASSI software has originally been developed at the UC Berkeley to conduct specialized seismic soil structure interaction (SSI) analysis. SSI is an essential component for the seismic safety analysis and design of nuclear power plants. All license applications for new reactors have used a version of SASSI in their SSI analyses. SASSI has also been extensively used in the seismic probabilistic risk assessments (SPRAs) for the seismic reevaluation of operating reactors. ACS SASSI is a commercial version of the SASSI developed and maintained for Windows-based platforms by Ghiocel Predictive Technologies Inc. Various applicants have used the ACS SASSI to perform SSI analysis in support of new nuclear reactor applications. The NRC also used ACS SASSI for confirmatory analyses in new reactor application reviews.

The Office of New Reactors (NRO) at the U.S. Nuclear Regulatory Commission (NRC) purchased the ACS SASSI about a decade ago to support the new reactor application reviews. The ACS SASSI has played an important role in supporting the staff's confirmatory analyses crucial to resolving critical seismic issues in application reviews. However, with the increasing computational capabilities in recent years, applicants have gradually transitioned from soil-structure models with a relatively small number of degrees-of-freedom to more realistic and detailed finite element models as well as enhanced SSI approaches. This transition required enhanced software capabilities, which the currently available NRC/NRO version of ACS SASSI can no longer fulfill. Currently, the Office of Nuclear Regulatory Research (RES) identified a need to upgrade the existing code to its latest commercial version. Therefore, RES initiated a maintenance action to upgrade the in-house ACS SASSI with increased its modeling capacity from a size with a few thousand degrees of freedom to sizes with several hundreds of thousands nodes and other capabilities potential applications will utilize such as fluid-structure interactions, nonlinear effects in SSI, probabilistic SSI, and use of random vibration technique (RVT) for seismic response analysis of structures. Both NRO and RES share the use of the upgraded program but RES maintain the operation of the program.

With this upgrade of the ACS SASSI, the NRC will be well positioned to support new and anticipated applications. As the NRC has worked with the ACS SASSI for more than a decade, the NRC has gained the required experiences and familiarity with such a specialized program. Therefore, purchasing an alternative new SASSI would not be cost effective as the NRC will have to climb a steep learning curve for new specialized programs. Further, other vendors for SASSI will not offer features such as fluid-structure interactions, nonlinear effects in SSI, probabilistic SSI, and use of random vibration technique (RVT) in a single package.
The benefit of the maintenance contract will be to afford updated features and new developments at no additional cost. RES will assess the need for extending the maintenance contract before the expiration of the one-year maintenance associated with the software upgrade.

The SASSI software was originally developed at the UC Berkeley to conduct specialized seismic soil-structure interaction (SSI) analysis. SSI is an essential component for the seismic safety analysis and design of nuclear power plants. The SASSI software performs a unique close form solution for SSI analyses which conventional software cannot provide. To this end, the NRC has accepted the method which SASSI provides for the soil structure interaction analyses in support of licensing applications. All license applications for new reactors have used SASSI in their SSI analyses. SASSI has also been extensively used in the seismic probabilistic risk assessments (SPRAs) for the seismic reevaluation of operating reactors. ACS SASSI is a commercial version of the SASSI developed and maintained for Windows-based platforms by Ghiocel Predictive Technologies Inc.

Various applicants have used the ACS SASSI to perform SSI analysis in support of new nuclear reactor applications. The NRC also used ACS SASSI for confirmatory analyses in supporting the new reactor application reviews because it offers the capabilities and features which other SASSI programs do not provide.
ACS SASSI has been widely used in seismic analysis and design by many applicants for design certificate and combined license applications. The NRC also used ACS SASSI for confirmatory analyses in support of the NRC application reviews and approval. With this upgrade, the NRC expects to continue its support for the regulatory
activities related to the seismic and structural engineering.

This noncompetitive acquisition is conducted under the authority of FAR 13.106-1(b). Only one source reasonably available.

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