Before we tackle environmentally-assisted fatigue (EAF), what is fatigue? In ASME Boiler & Pressure Vessel Section III Division 1, Subsection NB (in short, ASME III NB) fatigue refers to the damage caused by systems and components as a result of cyclic loads. The qualification of the primary coolant system of light water reactors (ASME III […]
by Greg Hollinger and George Antaki One of the qualification requirements for a piping system is to keep the loads imparted by the piping on equipment nozzles within certain allowable limits. These loads consist of sets of three forces and three moments, for the various load combinations. There are basically two types of nozzle load limits: […]
Becht Nuclear Services recently applied ANSYS® multi-surface, with fluid-structure interaction (FSI) capabilities to evaluate the effects of seismic loading on vessel internals that are immersed in the fluid. Before proceeding with the analysis of the actual vessel, the FSI capabilities were benchmarked to an analytical solution of a simpler liquid-filled flexible tank under seismic loading. […]
Currently there are nearly 100 commercial nuclear power plants operating in the US with most of the plants commissioned between the mid 1960’s and the mid 1980’s. All plants are designed to be capable of safely withstanding a postulated earthquake, known as the safe shutdown earthquake. Similar requirements are imposed on US Department of Energy […]
Design of a Nuclear Power Plant for a LOCA Nuclear power plants are designed with the capability to safely shut-down following a number of hypothetical accident scenarios. One of those accidents is the rupture of a pipe in the reactor coolant system (RCS). Such a rupture would result in a loss of coolant accident (LOCA), […]
Nuclear power plants are designed to be capable of a safe shut-down in case of a large design-basis tornado or hurricane. The magnitude of the postulated design-basis tornado or hurricane is such that there is less than 1 in 10 million chance (1E-7) per year and per reactor that it would be exceeded. This probability […]
It is normal for piping systems to exhibit steady pressure pulses. Most of the time these pulses are inconsequential; however, in a few cases they must be eliminated because they can affect the reliable operation of the system or they can cause a mechanical failure. Becht Engineering recently assisted a client in the evaluation of […]
Road Map of Regulatory Requirements General Design Criteria – The protection of nuclear power plants from the effects of tornadoes (or extreme winds from typhoons or hurricanes, depending on the locality) is required through 10CFR50 Appendix A, 10 CFR 50, Appendix A, General Design Criterion 2 which requires that structures, systems, and components (SSCs) important […]
Immediately following the Fukushima accident of March 11, 2011, the US Nuclear Regulatory Commission assembled a Near-Term Task Force to gather the lessons learned from the Fukushima Dai-Ichi accident. The Task Force compiled a set of “Recommendations for Enhancing Reactor Safety in the 21st Century.” The Recommendations were approved by the Commissioner and issued for […]
In welded structures, fatigue failures typically occur at the welded joints. Stress concentrations and small flaws in the welds are key parameters in determining the fatigue life of weldments. Traditionally, fatigue analysis of welded joints has been performed by attempting to determine the peak stress at the welded joint and then entering an appropriate “S-N curve” to estimate […]
