Active

Contract Opportunity

31310021P0003

Notice Type: Special Notice

Title

State-of-the-Art Containment Analysis with Computational Fluid Dynamics (CFD)

Synopsis

The U.S. Nuclear Regulatory Commission (NRC) intends to award a non-competitive, firm fixed price purchase order to ANSYS, Inc., 2600 Ansys Dr., Canonsburg, PA 15317 for the project entitled “State-of-the-Art Containment Analysis with Computational Fluid Dynamics (CFD)”.

The acquisition is conducted under the authority of Federal Acquisition Regulation (FAR) 13.106-1(b) which provides that contracting officers may solicit from one source if the contracting officer determines that the circumstances of the contract action deem only one source reasonably available (e.g., urgency, exclusive licensing agreements, brand-name or industrial mobilization).

The designated North American Industry Classification System (NAICS) Code is 513210-Software Publishers. The anticipated period of performance is two years.

Background

The U.S. Nuclear Regulatory Commission (NRC) anticipates reviewing new Small Modular Reactors (SMR) with in-containment passive containment cooling systems (PCCS) that involve a condensing surface. Specific reactors with these types of PCCS have already been evaluated by the staff and Phenomena Identification and Ranking Table (PIRT) reports have been developed. Important safety-significant phenomena involved in such SMRs include condensation in the presence of non-condensable gas (NCG) on the containment side and single-phase natural convection inside the PCCS. In both the PCCS and the containment at large, system level codes have considerable uncertainty in several areas, including convective flows, turbulent mixing, stratification, and condensation in the presence of NCG. NRC staff have used the system code TRACE for early evaluations of SMRs with this type of PCCS; TRACE has not been fully validated for analyses where condensation surfaces exist in large containment volumes with mixing, thermal stratification, and species transport playing a substantial role in the PCCS performance. Fundamentally, system level codes do not have appropriate models capable of evaluating three dimensional flows and mixing within a complex containment volume. These codes need to be informed with experiments and can benefit from comparisons with predictions by multi-dimensional higher order codes such as CFD.

Experiments are rarely prototypical due to the expense of building a full-scale system and augmenting experiments with CFD code predictions can help to extend the results to prototypical conditions. Typical multi-dimensional containment codes such as GOTHIC have limitations on geometrical complexity and turbulence modeling and require careful tuning to get good results. CFD tools can handle a wide range of flow conditions and geometric complexities, however, these codes are expensive to run and have limited two-phase capabilities. The continuous rise in computing capacity, currently being accelerated by advancements in graphics processing unit (GPU) computing, has led to a renewed interest in using CFD tools for large reactor system simulations such as containment analyses. In order to make these tools more applicable to containment analyses of this type, the wall condensation models need to be updated to include the capability to simulate prototypical condensation and liquid film behavior.

Recent CFD analyses examining the phenomena of interest to PCCS performance have been performed by NRC staff using ANSYS FLUENT. These analyses have been made difficult by limitations in the wall film post processing and highly simplified assumptions for the wall film itself. In order to more accurately predict PCCS performance in future SMR containment analyses, enhancements to the wall condensation modeling capabilities of ANSYS FLUENT are being sought.

Objective

The objective of this order is to develop enhancements to the condensation modeling capabilities of ANSYS’ CFD code, FLUENT. Improvements to FLUENT’s condensation modeling capabilities can be implemented via User Defined Functions (UDFs), for example. Improvements needed include modeling a condensate film’s transition to turbulence and the associated impact on heat transfer; effects of NCG; proper mass, energy, and momentum conservation; and accurate post-processing of condensation rates and mass and energy balances for surfaces of interest. The enhanced condensation model will be exercised on a benchmark case consisting of a steam-NCG environment and a thermosiphon heat exchanger with a vertical pipe section extending through that environment to condense steam on the outer pipe surface.

Contact

This Notice of Intent is NOT a request for proposal NOR a solicitation of offers; however, if any interested party believes they can meet the above requirements, it may submit a statement of capabilities. The statement of capabilities must be submitted in writing and must contain material in sufficient detail to allow the government to determine if the party can perform the requirements. Additionally, in order to perform work for the NRC potential sources must be free of organizational conflict of interest (OCOI). For information on the NRC COI regulations, visit NRC Acquisition Regulation Subpart 2009.5 (https://www.nrc.gov/about-nrc/contracting/48cfr-ch20.html).

A determination not to compete this proposed procurement based on responses to the notice is solely within the discretion of the Government. All interested parties must express their interest and capabilities in writing via email to Jeffrey R. Mitchell, Contracting Officer via e-mail at Jeffrey.Mitchell@nrc.gov no later than December 27 by 4:00 P.M. Eastern Time (i.e. 15 calendar days from the date this announcement was posted).

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