Seismic Upgrades

Nuclear Generating Station

After the Fukushima accident, the NRC developed a three-tiered prioritization of activities to enhance U.S. reactor safety.

Tier 1: Near Term 11 areas Identified
Tier 2: Mid Term 3 areas identified
Tier 3: Longer Term 13 areas identified


To reanalyze potential seismic effects using present- day request for information to determine if safety upgrades are needed.


A major Energy Company performed the Tier 1 Seismic Reevaluations for one of its Nuclear Plants. One area that was identified; the support buildings CMU block walls required strengthening. Various methods of reinforcement were evaluated and CFRP was the selected solution.


CMU Block Walls Common in Support Buildings

Composite Solution:

casestudy1-image04Seismic Upgrade using Carbon Fiber.
Seismic engineering determined the reinforcement requirements for the CMU block wall strengthening.

Testing was performed to verify material strength of CFRP samples using pull tests. These tests provided a final calibration of the CFRP design.

Five block walls were then prepped and CFRP was applied per the design documents.


Schematic Graphic showing expected behavior of CMU walls


Seismic compliant structures using CFRP methods and materials.

  • Very cost effective.
  • Simplified installation.
  • No safety issues and no change orders.
  • No need for an outage event to perform the work.