Project Details
[Return to Previous Page]Level Measurement with Time-Domain Reflectometry (TDR)
Company: GE-Hitachi Nuclear Energy LLC
Major(s):
Primary: EE
Secondary: ME
Optional: CMPEN
Non-Disclosure Agreement: YES
Intellectual Property: YES
Water level monitoring (WLM) in the RPV is critical during normal operation to maintain the optimum water inventory for core cooling and steam generation. In addition, it is imperative to maintain WLM capability during off-normal events and accident conditions in support of automatic or operator actions to restore normal conditions, or to maintain the plant in a safe condition. The primary WLM method in the industry is differential pressure (dP) and will also be the primary method for the BWRX-300. There are known issues with dP accuracy, especially during accident conditions. An alternate WLM method is Time-Domain Reflectometry (TDR) that offers some advantages over dP, especially during accident conditions. However, this method also has known issues with accuracy due to not knowing the exact electrical parameters of the steam and water. This project intends to characterize the parameters that cause inaccuracies and possibly develop correction algorithms to achieve high accuracy in all conditions. Test data will be obtained from the TDR test fixture This project can include analysis of the data to determine applicability and where improvements can be made. This may involve the addition of filtering, digital signal processing, and development of enhanced calibration algorithms. The RPV sketch attached illustrates the region where dP will be used to measure water level. Notice that the dP transducer pairs do not cover lower elevations such as over the core. Therefore, other supplemental methods are necessary to extend WLM coverage. TDR and/or HJTs are the likely methods that will supplement dP. A major challenge, and the primary objective for this project, is to understand how well each the TDR method performs under abnormal conditions. One example is when a rapid depressurization event occurs and the water inventory flashes resulting in voiding and mixed phase layers or gradients.
