Date of Defense
Date of Graduation
Chemical and Paper Engineering
Steam leaks occur in aging power systems due to heat energy loss in the valves of that system. A model was developed to determine the amount of heat energy lost in Donald C. Cook Nuclear Power Plant’s steam pipe valve system. Several methods were used to determine the mass flow rate and used to model the system in PEPSE. The PEPSE model determined the estimated energy that was lost due to seal leakage and general valve degradation. A program was created for use of plant employees to easily calculate the lost generation in MWe due to these leaks using the Grashof equation, ASME Figure 14, and the choke equation methods. This energy was quantified, and an economic analysis of the valves was performed to determine the lost revenue experienced by the power plant and compared that to the cost of replacing the valves with newer, more efficient models. The economic analysis of this project assumes the plant will have 350 days per calendar year of uptime. A 3-year recovery period MACRS analysis was used at the request of the company to determine a payback period (PBP). The company was not concerned about getting any specific minimum acceptable rate of return (MARR), so the MARR was set to 5% to cover at least the cost of inflation. The company was much more concerned with having a payback period of less than 3 years on any investments made. Ultimately, it was determined that replacing the top 10 leakiest valves in the system was not only financially feasible, but in fact would be quite profitable for the company, and therefore it was recommended for the company to proceed with the valve replacement. Even in the worst-case scenario where the new valves only save 55% more steam than the current valves, replacing the valves resulted in a total Net Present Value (NPV) of $14 million USD worth of savings over a 5-year period. The worst case also had the longest initial investment payback period (PBP) of 64 days, which is well within the 3-year goal.
Evans, Benjamin, "Steam Valve Thermo-Performance Analysis" (2020). Honors Theses. 3249.
Honors Thesis-Open Access