Company description

NRG is an independent nuclear engineering consultant and provides services to utilities, industrial suppliers and regulators (see www.nrg.eu). NRG was founded in 1998 by the merger of the nuclear engineering activities of KEMA and ECN. Its offices and facilities are located in Petten and Arnhem. NRG currently employs over 360 employees. NRG's activities are organised into three groups: Engineering, Environment and Irradiation Services. NRG Engineering provides services in the areas of Structural Integrity, Fitness for Service, Long Term Operation of Nuclear Power Plants and Safety and Licensing and is based in Petten. With its main assets, the High Flux Reactor and advanced Hot Cell Facilities, NRG Irradiation Services offers customer-specific fuels and structural materials testing programs for clients worldwide.

Introduction to the subject

Nuclear Reactor Safety is the primary focus for a nuclear reactor. The subject gained the attention of a larger public after the recent developments in Fukushima in Japan. One of the major areas in nuclear reactor safety is structural integrity, since the integrity of the reactor is crucial for the containment of radioactive materials. NRG assesses structural integrity of the High Flux Reactor in Petten and the Nuclear Power Plant in Borssele. To ensure the structural integrity on the long term, a Fatigue Monitoring Program is applied.

Research objectives

Structural Integrity of Nuclear Reactors Important systems that are covered by the Fatigue Monitoring Program are the primary and secondary cooling systems. A specific form of fatigue is fatigue due to thermal cycling. Strong links are observed between the Fatigue Monitoring Program and the Preventive Maintenance Process studied by Prof. Tinga. A graphical representation of such a program structure is shown below (Figure 1). Usage monitoring is done by measuring system state parameters like temperature, pressure and flow (Figure 2). Also detailed information about events occurred are logged. Finite Element Models are used to calculate the internal loads: stress levels in the specific components. Environmental assisted fatigue failure models are used to determine the accumulated damage

and the expected remaining life time.

Figure 1 Graphical representation of a Figure 2 Temperature measurement on

Preventive Maintenance Process the outside of the piping

The project will be part of the Fatigue Monitoring Program. Temperature transients are measured on the outside of the piping, while temperature loads are applied on the inside of the cooling system. One important step is to translate measured outside wall temperature transients into the inside cooling water temperature transients. You will develop an automated procedure to obtain the cooling water temperature transients. First with an iterative procedure.

Furthermore, you will investigate and eventually implement the Inverse heat transfer problem.

Student profile

Mechanical engineering

More information

NRG: Dr. Ir. Frederic Blom - blom@nrg.eu - 0224 568186 (Petten)

UT: Prof. dr. ir. T. Tinga