One-day lecture about vibrations in nuclear applications

What type of vibrations exists within the nuclear field? Why do they exist, and how can they be predicted and counteracted? These were some of the questions that Professor Rainer Nordmann addressed in his one-day lecture-tour in the Nordic Power Plants in Sweden and Finland in February and March 2022.

There is a need of knowledge transfer on how vibrations occur and how issues are best managed in nuclear applications. Apart from the need to increase and spread knowledge, there is also an opportunity to educate different function within the powerplant such as engineering, maintenance and operation.

To address these issues, Energiforsk arranged a full-day lecture with Professor Rainer Nordmann at the Nuclear Power Plants in Loviisa and Olkiluoto in February and Ringhals, Oskarshamn, and Forsmark. Rainer Nordmann is a consultant within smart structures and structural dynamics with applications to rotor dynamics at the Fraunhofer Institute in Germany. During his 40 years of university career at German Technical Universities, he focused on machine dynamics, rotor dynamics, and vibration control.

The seminar discussed vibration phenomena in turbogenerators for the typical systems in Nordic nuclear power plants. The sensitivity for vibrations and the risk for exciting vibrations is a combination of rotor mechanics, the flow in the turbine and the electrodynamics in generators. Vibrations is therefore a truly multidisciplinary field that requires a broad physical understanding.

The day was divided into four lectures:

  1. Introduction and vibration phenomena in turbogenerators
  2. Lateral vibrations in turbogenerators
  3. Torsional vibrations in turbogenerators
  4. Vibrations in generators of turbogenerators

One of the topics in Professor Nordmann's presentation was how to simulate, predict and diagnose interference from the electric grid. Grid interference is one issue within the area today where voltage variations and energy dips, can cause excitation and large mechanical vibrations in the entire turbine string.

– My impression is that the tour was greatly appreciated by a broad audience, with both an overall introduction and more specific lectures on how to study vibration phenomena with analysis and measurements, says Urban Andersson, area manager of the vibrations program.