Idaho Falls, ID

Idaho National Laboratory, Advanced Test Reactor, Primary Heat Exchangers Upgrade


The Advanced Test Reactor (ATR) at the Idaho National Laboratory (INL) supports research and testing of materials for use in large-scale and prototype reactors. Previous analysis by BEA raised potential concerns with the primary heat exchanger supports under a design earthquake. SGH evaluated the seismic performance of the primary heat exchanger supports and designed necessary upgrades.

The approximately 38 ft tall by 6 ft dia. heat exchangers located inside the reactor building are supported at their base by reinforced concrete piers, steel columns, and concrete walls; and are laterally supported near their top by tie rod bracing. For this project, SGH performed a structural evaluation and designed the upgrade for the primary heat exchanger supports for Performance Category 4 (PC-4)/Seismic Design Category 5C (SDC-5C) compliance. Our upgrade strategy focused on maintaining the stiffness of the existing load paths to preserve the validity of BEA’s previous dynamic analysis. Upgrades include new:

  • Upper tie rod bracing and ductile anchorage
  • Steel jacketing of supporting concrete piers for lateral and vertical confinement
  • Ductile lateral load path and base anchorage at the concrete piers
  • Ductile lateral load path and anchorage at the walls

We prepared calculations, design drawings and specifications, and three-dimensional fabrication and assembly drawings. SGH delivered a formal presentation to our client and our design work was independently reviewed and accepted. We also provided construction administration services that included review of the temporary scaffolding system.

Project Summary



Completion Date
Repair & Rehabilitation
Structures | Advanced Analysis
Science & Defense
Batelle Energy Alliance, LLC (BEA)
Specialized Capabilities
Seismic Engineering | Nuclear

Key team members

Michael Mudlock
Michael Mudlock
Associate Principal
Said Bolourchi
Said Bolourchi
Senior Principal