Lecture 2

Lecture 2 Introduction: Types of Fuels and Steam Generators1Fig. 2.1: Pressurized Water Reactor Fuel Bundle

3Fig. 2.2: Pressurized Water Reactor Fuel Bundle Details

4Fig. 2.3: Pressurized Water Reactor Fuel Rod

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Honeycomb type Spacer (Triangular Array)Tube SpacersAxially ConnectedTube SpacersTransversely ConnectedHoneycomb type Spacers (Square Array)Triangular Spacer

Fig. 2.4: Different Types of Spacer Grids6Rhombus typeSpacerRing typeSpacerSpacer CoilsFig. 2.5: PHWR Fuel Channel

7Fig. 2.6: PHWR Fuel: 19 Rod Bundle

ZIRCOLOY END PLATEUO2 PELLETSZIRCOLOY TUBE81.34 mm495.30 mm8Fig. 2.7: PHWR Fuel: 37 Rod Bundle

37 Element Fuel Bundle9Fig. 2.8: PHWR Fuel Channel Assembly and Fuel Bundle End Plates

10Fig. 2.9: Nuclear Reactor Steam Generator: Vertical Type

11Fig. 2.10: Nuclear Reactor Steam Generator: Vertical Type (Details)

12Fig. 2.11: Nuclear Reactor Steam Generator: Horizontal Type

13Fig. 2.12: Simplified Schematic of a Nuclear Reactor

14Nuclear Reactor Thermal Hydraulics StudiesNuclear reactor design based on defence-in-depth philosophyVarious thermal hydraulic phenomena need to be considered, under different conditions. These include: Heat transfer during normal operation: Heat transfer from fuel, Critical Heat Flux (CHF)Pressure drop in complex flow paths Flow distribution Plant operational transients: Examples are pump failure, turbine trip, etc. Design basis accidents (DBAs)Examples are Loss of Coolant Accident (LOCA), Loss of Regulation Accient (LORA), etc.Beyond design basis accidents (BDBAs):Consequences of multiple failures Example: LOCA followed by failure of ECCS/shutdown15Nuclear Reactor Thermal Hydraulics Phenomena/ Geometry Complex fluid flow phenomena/geometries need to be considered. These include:Single/two phase flow Critical flow, forced/natural circulation, flow distribution between parallel paths, condensation induced flow oscillations, counter current flow, etc. Horizontal/vertical flow paths Vertical pressure vessels with plenums and internalsHorizontal calandria vessels with internalsHeaders with parallel channels Multi-rod fuel bundles: In vertical/horizontal fuel channelsShort/longWith end plates/spacers Vertical/horizontal steam generators16