Seismic Testing - Clark Testing - IEEE 323 and 344

IEEE 323 and 344: Seismic Qualification of Safety Related Equipment for Class 1E Equipment



Class 1E equipment also known as “safety related” equipment are components, structures or systems associated with the integrity of the reactor pressure boundary and the ability to shut down and maintain the reactor in a safe manner. IEEE 323 & 344 are guiding certification documents to direct seismic qualification of Class 1E Equipment.

Clark Testing provides IEEE 323 & 344 seismic certification testing for manufactures selling Class 1E equipment and components for safety related use in a nuclear power application. Clark has a 10 CFR 50 Appendix B quality assurance program and is a member of the Nuclear Industry Assessment Committee (NIAC).

The Seismic table at Clark Testing is capable of performing seismic testing on large packages up to 20,000 lbs. at 1g ZPA. The table can achieve 3g’s ZPA up to 10,000 lbs. & 5g’s for lower weight. The table has three (3) independent servo hydraulic actuators with 38,000 lbs. force +/- 5” stroke with peak acceleration of 15g – 18g.

Common Technical Definitions Related to Seismic Testing Include:


  • Class 1E Equipment: Equipment known as safety related installed in a nuclear plant
  • 10 CFR Part 50: Nuclear Quality System
  • NPP: Nuclear Power Plants
  • IEEE: Institute of Electrical and Electronics Engineers
  • IEEE Standard 323 & 344 - IEEE Recommended Practice for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations.
  • OBE: Operating Basis Earthquake -the vibratory ground motion at which those features of the nuclear power plant necessary for continued operation without undue risk to the health and safety of the public will remain functional. OBE tests are generally one-half to two-thirds of the SSE levels. These are used to determine need for plant shut down due to an earthquake.
  • SSE: Safe Shutdown - the vibratory ground motion at which certain structures, systems, and components must be designed to remain functional. This term is used to identify the site-independent design ground motion.
  • RRS: Required Response Spectra
  • Seismic conditions of the buildings represented by RRS of the locations, on which the equipment subject to qualification is installed.
  • CSDR: Certified Seismic Design Response Spectra
  • GMRS: Ground Motion Response Spectra


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