Crystal River, FL

Crystal River Nuclear Power Plant Unit 3, Drop Load Analysis


The Crystal River Nuclear Power Plant, Unit 3, is part of a 4,700 acre energy complex that contains a 914 MW pressurized water reactor. When the client planned rigging operations for replacement of a steam generator at Unit 3, they required an assessment of potential damage to buried structures in the event of an accidental drop of the components. They also needed to determine safe lifting load paths to avoid failure of the water cooling system in operation during the replacement. SGH analyzed risks and modified lifting load paths to help mitigate damage.

As a part of the planning for steam generator replacement, SGH assessed the following primary buried structures under drop loads: 120 ft sea water room concrete wall, 48 in. dia. raw water discharge PCCP lines, 90 in. dia. circulating water PCCP Lines, and 48 in. dia. raw water intake ductile iron lines. We also inspected the 12 in. fire service lines, 18 in. storm sewer lines, and 4 in. floor drains. Highlights of our work include the following:

  • Identified and ranked the risks of drop loads based on location, height, and weight in defueled and power operation lifting modes
  • Conducted stress-wave propagation and contact-impact simulations for accidental component drops
  • Performed finite element analyses to account for energy dissipation through yielding of steel reinforcement, concrete cracking, and damping of stress waves in the soil media
  • Developed procedures for transferring dynamic analysis results to special structural evaluation software that would produce serviceability, damage, and failure limit states
  • Classified damage of buried structures into four levels: design code compliant; not fully code compliant but undamaged; damaged but functional; and structural failure
  • Developed new safe load paths for lifting operations to safeguard operation of the cooling system during the replacement

Project Summary



Completion Date
Repair & Rehabilitation
Advanced Analysis | Code Consulting
Progress Energy Company
Specialized Capabilities
Nuclear | Buried Infrastructure | Computational Mechanics | Risk & Resilience Assessment

Key team members

Mehdi Zarghamee
Mehdi Zarghamee
Senior Principal