Module I is a prerequisite for Module II.

It is advisable to have passed the exam of “PHYSICAL FUNDAMENTALS OF NUCLEAR ENGINEERING”, even if it is not mandatory.

Delivery: face to face

Learning activities:

• attending lectures
• individual study
• preparation of an oral/written report and its presentation
• bibliography search

Teaching methods:

• Lectures
• Seminars
• Project work

The Module I is organized in six main parts, described in the following.

Part I – General overview of NPPs

NPPs under operation in the world, forthcoming reactors and license renewals, GreenHouse Gas (GHG), emissions for various electricity generation sources, waste generation. Generation costs. Nuclear installations in France and in Italy. Generation of NPPs, classification of nuclear reactors on the base of energy spectrum, purpose, fuel, coolant, moderator, etc.. Typical data characteristic of NPPs.

Part II - Boiling heat transfer and two-phase flow overview

First definitions, homogeneous nucleation, heterogeneous nucleation, pool boiling regimes, pool boiling curve, heat transfer correlations for pool boiling. Flow boiling and two-phase flow: first definitions (void fraction, superficial velocity, flow quality, slip ratio, thermodynamic equilibrium quality and two-phase density). Boiling channel, two-phase flow regimes, flow pattern maps, flooding and flow reversal, heat transfer regimes in the boiling channel, Chen correlation, CHF (DNB and DRYOUT), flow boiling curve, main CHF correlations, Minimum CHFR. Overview of 1D balance equations for two-phase flow, components of pressure drop, friction pressure gradient and two-phase multiplier, pressure drop in a heated boiling channel.

Part III - Pressurized Water Reactors

Short history, reactor coolant system, coolant path inside the vessel, reactor vessel, internals, pressurizer, steam generators, VVER, reactor containment building, coolant pump, nuclear fuel, fuel pin and fuel assembly, control rods, burnable absorbers. Refuelling scheme and spent fuel, reprocessing, nuclear fuel cycle, thermodynamic cycle, steam turbine for NPP, steam condenser. CVCS, RHRS, ECCS, AFWS, CSS, Physical barriers in the defence-in-depth, inherent safety features of a NPP: core under-moderated and over-moderated.

Part IV - Boiling Water Reactors

Short history, Reactor Coolant System, comparison with PWR, recirculation system and jet pumps, Reactor Vessel and internals, fuel assembly, fuel rods, water rods, fuel enrichment, core characteristics, control rods. Reactor containments (dry, Mark I, Mark II and Mark III), comparison between the different containment types. Reactor Water Cleanup System, Standby Liquid Control System, Reactor Core Isolation Cooling, Emergency Core Cooling Systems, RHR System. Short presentation of Fukushima Daiichi accident.

Pat V - Reactivity, reactivity coefficients and fission product effects

Short review about the fission process, cross section and effective multiplication factor. Definition of reactivity and conventional unit of measure. Reactivity coefficients: fuel temperature, moderator temperature, void, pressure, power. Reactivity defect. Fission product effect on the reactivity of a NPP: burnup effect.

Part VI - Pressurized Heavy Water Reactors – CANDU

Short history, evolution of CANDU, Heat Transport System, moderator properties and motivation for the separation between coolant and moderator, comparison between CANDU and PWR. Feeder, header, steam generator, primary pump, calandria and core configuration, moderator cooling system, fuel bundle, fuel element, sheath, evolution of CANDU fuel bundle, mining to spent fuel storage, fuel channels arrangement in the calandria, fuelling machine, refuelling and heat flux distribution. Reactivity devices for CANDU 6, shutdown systems. Some safety requirements of the PHT, LOCA event and Emergency Core Cooling System, Reactor Containment. Good and bad features design of CANDU, Nuclear Safety Characteristics, reactivity coefficients.

Module II 

Energy prospects in the XXI century. New Build & Design Options Worldwide. The triangle of supply: IEA worldwide energy scenarios, Uranium supply, definitions of Reserve and Resources. Costs of nuclear power: definition of the Levelized Cost of electricity (LCOE), capital cost vs. overnight cost, plant operating costs including O&M and fuel costs.

Evolution of worldwide installed nuclear capacity. The NEA/IEA "Technology Roadmap for Nuclear Energy" document. Overview of the industrial development of PWRs.

Nuclear Energy around the Globe: USA (AP1000) and China (Hualong-one e CAP1400). South Korea (APR1400 and derived designs), UAE, Canada (EC6 and ACR1000), India, Japan and IAEA SSR-2/1, Russia (VVER market). Nuclear Energy in Europe: EU, France (EPR), UK, Sweden, Bulgaria, Switzerland, and other European countries.

IAEA categories for NPPs. Gen. III vs. Gen. III+ and their common characteristics.
US Design Certifications for Gen.III NPPs. Gen.III vs. Gen.III+ and their characteristics.

AP1000: Design objectives and key features: RCS, RPV (Mid-Loop Operation, Nozzles, Supports, Internals), Plant layout, Reactor core, Fuel rod & Fuel assembly, Control rods (gray and black rods), Integrated Head Package, SG, RCP main characteristics & functioning, Pressurizer, Normal RHR System, CVCS, Passive Safety Systems strategy, Passive Core Cooling System, Passive Heat Removal System, CMTs, Accumulators, ADS & valves, IRWST. SBLOCA phases and safety systems actuation. Containment characteristics, PCCS, different water supply systems, addressing SA (Hydrogen mitigation, In-Vessel Retention, long-term cooling). SBO sequence. SFP Cooling (in normal and accidental conditions).

AP1000 vs. EPR, their worldwide markets and problems, in particular for EPR in FIN, F, UK and Cina. The evolution of the French PWRs fleet. Description of the EPR plant, primary system, RS components dimensions, RPV description. Details on upper and lower RPV internals. Reactor core and distinct groups of fuel and HTM spacer grids, guide tubes. Fuel rods, RCCA (in detail), and instrumentation (in-core and ex-core). Safety systems.

Chinese NPPs: PWRs development path. HPR1000: general design, main primary system components, core, CF3 fuel assemblies, Safety Injection System, AFW System, Containment Spray System, SA-related systems. CAP1400: general overview, safety and economic performance, core and control rods, main components, non-safety grade systems vs safety-grade systems, IVR-related long term flooding.

Korean NPPs: derivation from CE System 80/80+. APR1400: design principles and  goals. RCS configuration and components, Safety Systems, Fluidic Device, SA mitigation.

Introduction to GEN IV: General goals and proposed reactor concepts. SCWR: fluid properties and relevant thermal hydraulic aspects (heat transfer deterioration phenomenon), limits of predicting tools. Examples of reactor designs proposed in the available literature (China, Japan, Canada, EU). Liquid Metal Fast Breeder Reactors. Short history. Conversion and Breeding. Core and blanket and comparison between FBRs & LWRs. Loop and pool types SFR.

VVER: distinguishing features, generations, standard versions, safety philosophy.

VVER-440: technical and safety aspects, plant layout. Safety improvements, design parameters, RPV and internals, reactor core, working assemblies, fuel assembly, ERC assembly, steam generator, CVCS, ECCS, containment, main deficiencies.

VVER-1000 (2nd gen): design evolution, safety advancement, plant layout, containment, primary system, design parameters, RPV and internals, flow paths, fuel assemblies, fuel rods, control rods, pressurizer, steam generator. Vertical SG vs Horizontal SG. secondary side, ECCS (HHPIS, HPIS, LPIS, Accumulators, Makeup system), additional safety systems.

VVER-1000 (3rd gen): AES-91, AES-92, advanced features, active and passive safety systems, fuel evolution, hydro-accumulators, PHRS, core catcher. Fuel Evolution.

VVER-1200: V392 & V491, Design Principles, Plant Sketch, Technical Data, Containment, Core, FAs, CRs, Primary Circuit, Layout, RPV. Main components (Barrel, Baffle, Protective Tube Unit, Top Head, Upper Unit, Steam Generator, Pressurizer, ...), Safety Principles & Safety Functions, Hydro-Accumulators (1st and 2nd stage), SG Passive Heat Removal System, Containment Heat Removal System. Safety Systems (V392 vs V491). VVER-TOI: layout, main improvements, safety systems.

Graphite-Moderated Reactors (GMRs). Graphite used as moderator: characteristics and main parameters. Short history: UK prototypes, GLEEP, BEPO, Windscale Pile.

Magnox reactors: general concept and development; plant layout and main components; core and fuel configuration, materials, and operations. Introduction to Advanced Gas-cooled reactors (AGRs). Pressure vessel and main components. Coolant flow paths. Reactor core main layout. Fuel assemblies' characteristics. Operational characteristics.

Introduction to RBMK reactors. Main characteristics and flaws of water as coolant and graphite as moderator. Fuel assembly and core configurations. Coolant flow path in fuel channels. Refueling operation. Videos on Chernobyl accident.

HTGR reactors: evolution of prototypes and commercial reactors. BISO and TRISO fuel characteristics. Fuel main configurations: hexagonal stacks and pebble bed. Shut down reactors: UK Dragon reactor, Germany AVR reactor. Peach Bottom reactor. Commercial reactor: Fort St. Vrain main features and reactor arrangement. Research reactors working today: Japan HTTR and China HTR-10. Pebble Bed reactor general concepts. Germany THTR-300. Pebble bed Modular Reactor. China HTR-PM design. GT-MHR design and reactor features. Advantages of HGTR and comparison with LWR.

Main recommended reading includes notes personally prepared by the teachers specifically for this course. Further recommended reading includes parts of the following textbooks:

- B. Guerrini, S. Paci, “Appunti di Impianti Nucleari”, Dedalo Edizioni, Pisa, 2011.

- S. Paci, "Introduzione ai sistemi nucleari", Pisa University Press, 2021.

- Cacuci D.G., “Handbook of Nuclear Engineering”, Springer, 2010.

- Lamarsh J.R., Baratta A.J. "Introduction to Nuclear Engineering", IV ed., 2017.

- Kenneth D. Kok, "Nuclear Engineering Handbook", II ed., 2016.

- Pioro I.L., "Handbook of Generation IV Nuclear Reactors", II ed., 2022.

Further bibliography, including reference handbooks, will be indicated by Lecturers.

The teaching material will be available on-line normally before the lectures will be done.

Further information and questions can be asked to the teachers by e-mail or fixing an appointment.

Oral exam. In some cases, a concise list of written questions can be assigned to let the student take notes and then discuss with the teachers orally at the beginning of the oral exam.

Google Classroom Web Page for Module I that will be communicated at the beginning of the course. Anyway, a link to Google Classroom will be available in the Class Web Page.

The lectures for Module II will be loaded on Teams