Our senior engineers have expertise in design, materials, thermal analysis, fatigue, vibration /seismic analyses, and fracture mechanics in extending the life of critical components. Dr. William J. O’Donnell, President, co-invented the Mechanical Stress Improvement Process used to relieve stresses in welded joints subjected to stress corrosion cracking. The process has been applied in many nuclear power plants throughout the world.
- Structural Design and Analysis
Three dimensional finite element analyses were used to design numerous Class 1 nuclear components. Stress indices were developed for pressure and external loadings on piping components in simplified design procedures.
- Tube-and-Tubesheet Analysis
General methods for calculating stresses and strains due to mechanical and thermal - induced loads were developed for tubesheets. Extensive development work has been completed on tube-to-tubesheet joints. Inelastic analyses were used to quantify the hydraulic pressures needed for the expanded tubes, and the pressure needed in the neighboring tubes to protect the ligaments.
- Design Criteria
The U.S. Nuclear Regulatory Commission (NRC) and Westinghouse jointly chose Dr. O'Donnell to develop design criteria and methods for the acceptance of flaws using fracture analysis of perforated tubesheets in steam generators to satisfy NRC requirements. The solution applied finite element methods to determine nominal stresses in the tubesheet subjected to thermal and mechanical loads. Failure modes for leaks and criteria for failure were investigated.
- Steam Generator Tubing Wear
Steam generators at a particular client site were experiencing tube wear due to flow induced relative motions between the tubes and the stabilizing spacers (batwings). Flow induced vibration analysis methods were applied to analyze local wear conditions and provide a method of quantifying tube wear rates and predicting expected tube life.
- Mechanical Stress Improvement Process
In considering the stress corrosion cracking problem in the heat affected zone of field welds in BWR primary pumping, we developed a reliable mechanical stress improvement process which applies compressive stresses and is easy to control and verify. MSIP was developed with supporting finite element analysis and tests which show that it provides compressive stress fields in both the axial and circumferential directions at the inner surface of weldments. The Process was developed for pipe-to-pipe, pipe-to-discontinuity (such as valve body) and pipe-to-vessel nozzle configurations. MSIP has been performed at 40 nuclear power plants worldwide.
Our senior staff invented, built, and installed a pipelock on an elbow degraded by stress corrosion cracking in the primary system of a nuclear power plant.
- Thermal Shield Repair
Flow induced vibrations were evaluated in the thermal shield of the San Onofre Nuclear Plant. O'Donnell designed a support system which was installed to control the amplitude of vibrations within acceptable limits.
- Design and Analysis
Reactor systems & internals; steam generators; reactor coolant pumps; seals; motors; safety systems; containment structures; piping & supports; turbines; generators; valves & other components.