The course is in the second year of energy and nuclear engineering and its aim is to provide students with methods for the evaluation and design of nuclear power plants and the development of their safety analysis.
The course consists of lectures and numerical evaluations.

At the end of the course, the students will have a deep knowledge of the characteristics and safety requirements of nuclear power plants, of phenomena occurring in both Design Basis Accidents and Severe Accidents; moreover, the students will have the knowledge necessary to the design of safety features and to the development of Probabilistic Risk Assessment.

Basis concepts of reactor physics, nuclear plants, single-phase and two-phase fluid dynamics and heat transfer.

1. Nuclear Risk. Design criteria for protection system, engineered safety features and auxiliary systems. Critical accident sequences and safety classes.
2. Phenomena and simplified models of typical accidents in Light Water Reactors.
2.1 Loss of Flow Accidents (LOFA): pump coast-down and heat removal by natural circulation.
2.2 Loss of Heat Sink: loss of feedwater, steam line break;
2.3 Reactivity Insertion Accidents (RIA)
3. Loss of Coolant Accidents (LOCA): subcooled blowdown, water hammer, satured blowdown, dryout, flooding and refilling.
4. Probabilistic Risk Assessment (PRA):
4.1 Aims and results of the three levels of PRA.
4.2 PRA level 1: Master Logic Diagram for the determination of initiating events, event tree and fault trees for the evaluation of the occurrence probability of accidental sequences.
4.3 PRA Level 2: in-vessel and ex-vessel phenomena in severe accidents, loads on containment system and modes of failure, release of radioactive fission products from fuel, coolant system and containment system.
4.4 PRA level 3. Results of WASH 1400.

The theory is complemented by numerical examples and students are invited to apply the analytical models and develop computer programs in order to evaluate the time behaviour of the most important thermal-hydraulic parameters during LOFA, RIA and LOCA accidents. Event tree and fault tree techniques will be applied in the definition of accident-sequences in a real PWR.

- N.E.Todreas and M.S.Kazimi,"Nuclear systems",Vol.I ,II,Hemisphere,1990.
- R.T.Lahey and F.J.Moody,"The thermal-hydraulics of a boiling water reactor",American Nuclear Society, New York, 1993.
- L.S.Tong and J.Weisman,"Thermal analysis of pressurized water reactors",American Nuclear Society, La Grange Park,1996.
- E.E. Lewis, Nuclear power reactor safety, Wiley, New York, 1977.
- N.J. McCormick, Reliability and risk analysis, Academic Press, London, 1981.

The exam, at the end of the course, is oral and it includes a discussion of the results obtained in the laboratory sessions.