Piping / Hydraulic Analysis
While many people are familiar with GOTHIC’s application to
room heat-up and HVAC applications, its features and applicability are
much greater. One broad area of application is hydraulic analysis of
piping systems and tanks. Red Wolf Associates has the capability to
perform steady-state and transient pipe flow analyses to support a
variety of applications.
Our personnel also have created hydraulic models of other piping such as chilled water systems and fire protection systems to evaluate the impact of component failure or piping obstructions. Using a GOTHIC model that has been benchmarked to design or tested conditions, the off-design condition or proposed modification can be added to the model and the impact on system parameters such as pressures, flow rates, etc. can be assessed. If the fluid under investigation flows through the primary or secondary side of a heat exchanger (either water-water or air-water such as a cooling coil), the impact on the heat transfer can be determined directly in the GOTHIC analysis by modeling this equipment with heat exchanger components. These features of the code offer extreme flexibility to the end-user and can provide much needed margin to meet design or regulatory requirements. The Red Wolf Associates staff has completed many analyses coupling these features together to assist with plant modifications, NRC finding mitigation, etc.
Red Wolf Associates personnel have extensive experience modeling many different phenomena associated with nuclear plant piping systems. Having been involved with the ongoing development and maintenance of the GOTHIC code, we are knowledgeable with its limitations and range of applicability. This combination of knowledge and experience for such applications allows us to best serve you. If you have a technical challenge that could possibly be evaluated with GOTHIC, please contact us. We can tell you if GOTHIC is the best tool for your application and, if it is not and we are otherwise unable to assist with your need, we can direct you to an appropriate vendor or tool.
Gas Transport
Red Wolf Associates personnel have been at the forefront of addressing gas intrusion in ECCS piping. They were key developers of GOTHIC modeling methodologies to analyze void transport in ECCS suction piping. Models can be used to determine the void fractions at the suction of the pumps to reveal if limits provided by pump vendors and general NRC guidance are exceeded. Various pump configurations are typically assessed to determine the limiting condition based on the postulated accident scenarios and individual pump and train failures. The models typically show that significant attenuation of the air would occur as it is transported to the pump, reducing the void fraction at the pump to acceptable levels.Water Hammer
Red Wolf Associates personnel have modeled water hammer transients as a result of air and steam voids in discharge piping. Three-dimensional GOTHIC models to evaluate the potential for pipe support failure and relief valve lift in ECCS discharge piping due to air voids can be created. These analyses determine the peak discharge pressure due to the transient and can also determine the dynamic loads the transient places on the pipe supports. Pressure transients for very long and complex piping configurations such as fire protection systems can be evaluated with two-dimensional GOTHIC models. These column-closure transients require evaluation due to failure of keep-fill pumps or over-pressure tanks. Failure of the keep-fill systems allows steam voids to form in tall risers which collapse when the pumps are started. In these cases the entire system is typically modeled so that interactions between pressure waves reflecting through the system are properly accounted for in determining the peak system pressure and pipe support loads.Typical Piping Analyses
GOTHIC can also be used for more typical hydraulic calculations such as NPSH, flow balancing, equipment modifications, etc. Red Wolf Associates can produce transient NPSH calculations to evaluate NPSH margin during switchover to PWR sumps. These calculations can be completed using stand-alone models or, in some cases, coupled with a GOTHIC containment model to credit the pressurization as needed to meet NPSHR.Our personnel also have created hydraulic models of other piping such as chilled water systems and fire protection systems to evaluate the impact of component failure or piping obstructions. Using a GOTHIC model that has been benchmarked to design or tested conditions, the off-design condition or proposed modification can be added to the model and the impact on system parameters such as pressures, flow rates, etc. can be assessed. If the fluid under investigation flows through the primary or secondary side of a heat exchanger (either water-water or air-water such as a cooling coil), the impact on the heat transfer can be determined directly in the GOTHIC analysis by modeling this equipment with heat exchanger components. These features of the code offer extreme flexibility to the end-user and can provide much needed margin to meet design or regulatory requirements. The Red Wolf Associates staff has completed many analyses coupling these features together to assist with plant modifications, NRC finding mitigation, etc.
Red Wolf Associates personnel have extensive experience modeling many different phenomena associated with nuclear plant piping systems. Having been involved with the ongoing development and maintenance of the GOTHIC code, we are knowledgeable with its limitations and range of applicability. This combination of knowledge and experience for such applications allows us to best serve you. If you have a technical challenge that could possibly be evaluated with GOTHIC, please contact us. We can tell you if GOTHIC is the best tool for your application and, if it is not and we are otherwise unable to assist with your need, we can direct you to an appropriate vendor or tool.
Red Wolf Associates, PLLC © 2012
