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TerraPower will be providing an interactive workshop describing and demonstrating a newly-released open source nuclear engineering analysis automation tool. This software system, called ARMI, creates a digital “reactor at your fingertips”, enabling new levels of productivity, detail, and quality for engineers studying or evaluating nuclear reactors.

TerraPower has used ARMI with their internal set of physics plug-ins for over a decade to automate the entire analysis chain of various fast reactor core analyses. They can now have a supercomputer adjust the cladding thickness in a fuel pin in a statistical distribution and have an entire equilibrium fuel cycle analysis with loosely (or tightly) coupled thermal hydraulics and fuel performance be performed. Levelized cost of electricity and transient performance in a series of design-basis accidents are evaluated and functionalized. This enables robust and deep multi-objective optimization considering the entire system with a very small and efficient engineering team. The overall system at TerraPower integrates third party codes (like ANL’s fast reactor suite) with internal physics tools (e.g. for depletion, equilibrium fuel cycle, flux reconstruction, subchannel T/H, core mechanical, fuel performance, etc.)

TerraPower decided to open-source the framework behind its storied automation capabilities as a way to increase collaboration and efficiency in the nuclear industry. We believe that by opening up these tens of thousands of lines of nuclear-specific data model, automation, data persistence, optimization, and utility code, we can push the “commodity” parts of the envelope together.

We hope that the community will begin to create plug-ins connecting ARMI to  the wide and rich variety of physics kernels in use today. To start, we will open-source a few of our own and offer others with proprietary licenses. We believe that the open-source model of data management will foster a continuously improving ecosystem of interoperable reactor analysis software. Once we build a “critical mass”, the value of connecting your specialized tool to ARMI will be self-reinforcing:

Your code will have automatic loose and/or tight coupling capabilities with all other ARMI-integrated plugins Your code will be immediately runnable with all community (or proprietary) ARMI input decks (e.g. of common benchmark problems), so we can reduce the amount of benchmark re-work done as a community

Your code will work with any established ARMI methodology/workflow (good for head-to-head comparisons) You will never be locked into any proprietary software automation ecosystem because ARMI is licensed under a permissive Apache open-source license.

Since TerraPower invested in the system for 10 years straight, its capabilities are tried and true in advanced reactor design/engineering scenarios. TerraPower has built ARMI models of FFTF, EBR-II, JOYO, TWR designs, many ZPR and ZPPR configurations (Cartesian geometry), the VTR, and the TerraPower Molten Salt Reactor (MCFR). They have taken minor steps towards representing thermal reactors in ARMI and ARMI does include a very simple C5G7 LWR benchmark sample input deck, but we hope the community will help extend into this scope. TerraPower’s investment in ARMI has certainly been primarily prioritized based on the evaluation of sodium-cooled fast reactors, but the Framework is intended to be generic.

Beyond the core, the ARMI vision includes models of the plant. This would enable the automation of plant system analysis, opening up relevance to broader scope design as well as for increasing engineering efficiency in the operating fleet.

This workshop will introduce the concept and design of ARMI, share some success stories about how it can be useful, and then will interactively go through the installation of the open-source ARMI framework (downloaded from GitHub) and some interactive first tutorial. To participate, you should bring along a Windows, Mac, or Linux laptop with Python 3.6 or greater on it, and with internet access. We will build a virtual environment for the demo and go from there. Alternatively you can go through the installation instructions in advance to get a head start, and let us know if you have troubles during the workshop.

The code is available today at

Read more about its use at TerraPower in the 2017 open-access article: Touran, Nicholas W., et al. “Computational tools for the integrated design of advanced nuclear reactors.” Engineering 3.4 (2017): 518-526.