Ringhals Diagnostics and Monitoring, Annual Research Report 2019-2020

This report gives an account of the work performed by the Division of Subatomic, High Energy and Plasma Physics (formerly, Division of Nuclear Engineering), Chalmers, in the frame of a research collaboration with Ringhals, Vattenfall AB, contract No. 686103-003. The contract constitutes a 1-year co-operative research work concerning diagnostics and monitoring of the BWR and PWR units.The work in the contract has been performed between July 1st 2019, and June 30th, 2020. Originally, we planned to work with five items as follows:1. Continued investigation of possible baffle jetting in R3 with noise analysis of in-core and ex-core detector signals;2. Further analysis of the vibrations of thimble tubes with axially dependent in-core measurements in various radial positions;3. Evaluation of new ex-core measurements for beam mode and tilting mode vibrations in R3;4. Experimental work and simulations in support of the use of fission chambers in the current mode for reactor diagnostics, as an alternative of pulse counting methods;5. Development of a new method to determine the axial velocity profile of the void in the core of a BWR by using four permanent in-core LPRMs and a TIP detector.Due to changed circumstances, mostly related to the Covid-19 pandemics, some changes were made in the project. Item #1 was reduced, whereas the work planned in item #2 was postponed to the next Stage. The work was performed by Imre P\ue1zsit (project co-ordinator), Luis Alejandro Torres and Cristina Montalvo (research collaborators from UPM, Madrid), Lajos Nagy (double degree PhD student jointly with BME Budapest), Gergely Klujber and M\ue1t\ue9 Szieberth (research collaborators from BME), Tsuyoshi Misawa and Yasunori Kitamura (research collaborators from KURNS, Kyoto, Japan) and Henrik Nyl\ue9n, the contact person at Ringhals