Plymouth, MA

Pilgrim Nuclear Power Station Frac Tank


In response to Nuclear Regulatory Commission (NRC) post-Fukushima (FLEX) requirements, Entergy sought to install a 21,000 gal, mobile frac tank for temporary water storage at their Pilgrim Nuclear Power Station (PNPS). SGH evaluated the structural and seismic performance of the steel tank, manufactured by PCI Manufacturing, LLC.

SGH reviewed the design proposed by PCI Manufacturing, LLC and provided recommendations to ensure adequate strength and stability. Highlights of our work include the following:

  • Completed a response spectra fluid-structure interaction analysis of the frac tank for FLEX ground response spectra Safe Shutdown Earthquake (SSE) and Operating Basis Earthquake (OBE) cases, impulsive and convective (sloshing modes) for multiple fluid water levels, and sloshing effects on the tank roof per ANSI/AWWA A121
  • Evaluated the structural adequacy of the tank to resist a combination of seismic and non-seismic demands
  • Designed structural modifications to ensure all component stresses were below allowable values per ANSI/AISC N690 and 360
  • Inspected the frac tank structure for conformance to the design requirements
  • Analyzed proposed welds following ANSI/AISC provisions and inspected welds in final configuration per AWS D1.1
  • Evaluated stability of the frac tank using nonlinear sliding and overturning provisions of ASCE/SEI 43

Project Summary



Completion Date
New Construction
Structures | Advanced Analysis
Science & Defense
PCI Manufacturing LLC
Specialized Capabilities
Seismic Engineering | Nuclear

Key team members

Michael Mudlock
Michael Mudlock
Associate Principal
Ronald Mayville
Ronald Mayville
Consulting Principal