http://bzuiam.webs.com/

1. LOW PRESSURE REACTORS

2. Muhammad Umair Bukhari
Engr.umair.bukhari@gmail.com
www.bzuiam.webs.com
03136050151

3. OVERVIEW
I’ll discuss here:
 What is nuclear energy?
 Nuclear reactor
 Nuclear power plant
 Types of nuclear reactors and
 Nuclear reactor hazards

4. What is nuclear energy?
Nuclear energy produces electricity from heat
through a process called fission. Nuclear power
plants use the heat produced by fission of certain
atoms.
1. Nuclear fission
nucleus of atom is split into parts,
produces free neutrons and
energy

5. Nuclear Reactors
Nuclear Reactor  device built to
sustain a controlled nuclear fission
chain reaction
Main Components of Nuclear
Reactor:
- reactor vessel
- tubes of uranium
- control rods
- containment structure
http://en.wikipedia.org/wiki/Image:Crocus-p1020491.jpg
Containment control
control rods structure
radioactivity, absorbs
contains the reaction
neutrons
in at least 3 feet of
concrete!
www.pbase.com/pbrakke/image/44279993

6. The Nuclear Power Plant
Nuclear power plant
consists of all the
parts needed to create
electricity by using
Fission occurs The heat is used nuclear energy
in the reactor to heat water to
vessel. Heat is create steam
produced.
The steam is
The steam is used to turn the
cooled in the turbine in the
condenser to generator to
return to the produce
liquid phase. electricity

7. Types of Nuclear Reactors:
 Thermal Reactors and Fast Reactors
 Homogeneous and Heterogeneous Reactors
 Low Pressure and High Pressure and Reactors
Low Pressure Reactors:
 Pressure is normally 7MPa
 Water boils in the core of the reactor
 Low pressure reactors are working in a “DIRECT CYCLE”
Most common low pressure reactors are:
 Boiling Water Reactors BWR
 Advanced BWR, ABWR
 Economical Small Boiling Water Reactor (ESBWR)
 RBMK Reactor

8. Boiling Water Reactors BWR:
• Direct Boiling • UO2 Fuel
• 10% Coolant = Steam • 60 – yr Service Life
• 3.2% U-235 Fuel • Internalized Safety and
• Lower Power Density than Recirculation Systems
PWR
• Corrosion Product Activated
in Core
• Higher Radiation Field

9. http://www.nrc.gov/

10. • 1350 MWe
• 77% more compact than
BWR design
• 39 month construction period
GE
TOSHIBA, Kashiwazaki-Kariwa Unit 6, Japan

12.  Early 1990s - TEPCO, 5 other utilities, GE, Hitachi
and Toshiba began development
 1700 MWe
 Goals
30% capital cost reduction
Reduced construction time
20% power generation cost reduction
Increased safety
Increased flexibility for future fuel cycles
 Commercialize – latter 2010s

13.  1550 MWe (4500 MWt)
 Passive Condenser Systems
for Heat Transfer
 Standard Seismic Design
 Improved Economics
 Shorter Construction Time
 Reduced Plant Staff and
Operator Requirements

14. RBMK Reactor
 High Power Channel-type Reactor
 Graphite-moderated
 1986 Chernobyl disaster
 Reactor pit is made of reinforced concrete
 Pit Dimensions 21.6 21.6 25.5 meters
 Vessel of the reactor, made of a cylindrical wall and top and bottom metal plates
 Moderator blocks are made of nuclear graphite of dimensions 250 250 500
mm
 There are holes with 11.4 cm (4.5 in) diameter
 Cylindrical core 14 m (45 ft 11 in) in diameter and 8 m (26 ft 3 in) high
 Maximum allowed temperature of the graphite is less or equal to 730 C (1,350
F)
 Top of the reactor is covered by the upper biological shield, called "Schema E"
 Fuel channels consist of welded zircaloy pressure tubes 8 cm (3.1 in) in inner
diameter with 4 mm (0.16 in) thick walls
 There are 1661 fuel channels and 211 control rod channels in the reactor core
 UO2 pellets 1.15 cm (0.45 in) in diameter and 15 mm (0.59 in) long
 Emergency Core Cooling System (ECCS)

16. Nuclear Reactor Hazards
 Radiation effects to the workers of plant
 Radiation effects on environment and atmosphere
 Power plant is a major threat for public in case of a disaster like
Chernobyl
 Ageing process of nuclear reactors produces:
 Small leakages
 Cracks
 Short-circuits due to cable failure
 Gradual weakening of materials
 Embrittlement of the reactor pressure vessel
 There is also a threat of terrorism attack
 That attack may be from air, water or firing on plant from a
distance
 Spent fuel pool disaster
 Radioactive waste storage disaster
 Two major nuclear reactor disasters are Three miles island and
Chernobyl