Ringhals Diagnostics and Monitoring, Annual Research Report 2018-19

Rapport, 2019

This report gives an account of the work performed by the Division of Subatomic and Plasma Physics (formerly, Division of Nuclear Engineering), Chalmers, in the frame of a research collaboration with Ringhals, Vattenfall AB, contract No. 677353-003. 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 1 July 2018 – 30 June 2019. During this period, we have worked with five main items as follows:

1. Investigation of possible baffle jetting in R3 with noise analysis of in-core and ex-core detector signals;

2. 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. Development of a method to use the Eigenvalue Separation in noise analysis for characterising regional power oscillations and understanding the role of loosely coupled cores in the development of regional instabilities;

5. Further investigations of the possibilities of using fission chamber signals for measurement of subcritical reactivity, such as elaboration of the equivalent of the Feynman-alpha method of pulse counting, and accounting for delayed neutrons.

The work was performed at the Nuclear Engineering Group of the Division of Subatomic and Plasma Physics, Chalmers University of Technology, by Imre Pázsit (project co-ordinator), Luis Alejandro Torres (visitor from UPM, Madrid, Spain), Cristina Montalvo (research collaborator from UPM), Yasunori Kitamura (research collaborator from KURNS, Kyoto, Japan), Lajos Nagy (double degree PhD student) and Henrik Nylén, the contact person at Ringhals.