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PWR, BWR, CANDU, LIGHT WATER REACTOR (LWR), ADVANTAGES/DISADVANTAGES,…

- - - - reactor core: where fission reactions take place
      - reactor pressure vessel: protects the reactor core and
        maintains the pressure boundary of the reactor core
      - pressuriser: maintains the pressurised state by
        adjusting the pressure of the primary system
      - coolant pump: circulates the reactor coolant
      - steam generator: transfers the thermal energy to the
        secondary side to generate steam
    - - ADVANTAGES
        
        small reactor size due to the role of the coolant as an effective moderator
        
        relatively high conversion ratio of nuclear fuel to fissile materials
        
        large specific heat of water provides the advantage
        of preventing the nuclear fuel from being extremely
        overheating during reactor transients thereby
        enhancing safety of the reactor
        
        no leakage of coolant during normal operation
        
        Most fission products are confined in the nuclear
        fuel
      - DISADVANTAGES
        
        Since neutron absorption cross-section of light water is much larger than heavy water, enriched uranium (2-5%) should be used as nuclear fuel to maintain the criticality continuously
        
        Periodic shutdown is required to replace the nuclear fuel
  - - - The secondary system including the turbine has
        more possibility of contamination by radioactivity
        since the reactor coolant boiled to steam inside the
        reactor core directly enters the turbine
      - Reactor control during normal operation is
        relatively easy due to the negative reactivity
        induced by boiling
      - A sudden increase in steam pressure will result in
        the sudden decrease in the proportion of steam to
        liquid water inside the reactor. The increased ratio
        of water to steam will lead to increased neutron
        moderation, which in turn will cause an increase in
        the power output of the reactor
- - - - Canada: 19 and 5 decommissioned.
        South Korea: 4, China: 2.
        India: 2, 13 active CANDU-derivatives, and 3 CANDU-derivatives under construction.
        Argentina: 1, and 1 planned, Pakistan: 1.
        Romania: 2, and 2 dormant part-constructed.
  - - - REACTOR COOLANT PARAMETERS
        
        OUTLET HEADER TEMPERATURE - 310 'C
        
        OUTLET STEAM QUALITY(MAX) - 4.0%
        
        OUTLET HEADER PRESSURE - 10MPa
        
        INLET HEADER TEMPERATURE - 266'C
      - SECONDARY SIDE CONDITIONS
        
        STEAM QUALITY - <0.25% moisture
        
        FEEDWATER TEMPERATURE - 187'C
        
        STEAM PRESSURE - 4.7MPa
    - - LOW TEMPERATURE (<80'C), LOW PRESSURE SYSTEM
      - INDEPENDENT OF REACTOR COOLANT SYSTEM
      - NORMAL HEAT REMOVAL (~4-5%) OF FULL POWER
      - CONTAINS REACTIVITY DEVICES OUTSIDE OF HIGH-PRESSURE HEAT TRANSPORT SYSTEM
      - POTENTIAL HEAT SINK IF EMERGENCY CORE COOLING IS UNAVAILABLE DURING LOSS OF COOLANT ACCIDENT (LOCA)
    - - NATURAL URANIUM (~0.7% 235U)
      - HIGH DENSITY URANIUM OXIDE(UO2) FUEL PELLETS IN ZIRCALOY-4 CLADDING
      - SHORT(0.5m) FUEL ELEMENTS ARRANGED IN CYLINDRICAL FUEL BUNDLES
    - - ALL LOCATED PERMANENTLY POSITIONED IN LOW-PRESSURE MODERATOR ENVIRONMENT
      - GUIDE TUBES LOCATED INTERSTITIALLY BETWEEN ROWS OF CALANDRIA TUBES
      - FOR REGULATION (CONTROL)
        
        14 LIQUID-ZONE-CONTROL COMPARTMENTS (H2O FILLED)
        
        21 ADJUSTER RODS
        
        4 MECHANICAL CONTROL ABSORBERS
        
        MODERATOR POISON
        
        FOR EMERGENCY SHUTDOWN
        
        2 SHUTDOWN SYSTEMS (SDS-1 & SDS-2)
        
        SDS-1: CADMIUM RODS ENTER CORE FROM TOP
        
        SDS-2: INJECTION OF GADOLINIUM NEUTRON "POISON" FROM SIDE
    - - SHIELD TANK
        
        FUEL CHANNELS
        
        END-SHIELDS
        
        REACTIVITY CONTROL DEVICES
        
        CALANDRIA VESSEL
        
        CONTAINS HEAVY WATER MODERATOR
        
        CONTAINS REACTIVITY CONTROL DEVICES & SHUTDOWN SYSTEM
        
        INC CALANDRIA TUBE & SUPPORT PRESSURE TUBE
        
        EMBEDDED IN LIGHT-WATER REACTOR VAULT ( provides radiation shielding)
        
        LOW-PRESSURE TANK