1.
Reactor Engineering
NE – 4 (Lecture - 22) AHWR
S. Dayal ACE KM

2.
AHWR
• Developed to use Thorium for generation of
commercial nuclear power
• 300 MWe
• Pressure Tube type reactor: vertical PT
• Boiling Light Water: BLW
• Passive Safety Features
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3.
Safety Features AHWR
• negative void coefficient of reactivity.
• Passive safety systems
• Heat sink in the form of Gravity Driven Water
Pool GDWP
• Removal of core heat by natural circulation.
• ECCS injection directly inside the fuel. .
• Two independent shutdown systems.
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4.
+ Features of AHWR
• No Hi Pressure D2O as coolant, no leakage
loss / recovery systems
• Recovery of heat generated in Moderator
System for feed-water heating
• Shop assembled coolant channels, quick
replacement of pressure-tube
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5.
+ Features of AHWR
• Steam Drums in place of steam-generators
• Higher Steam pressure than in PHWR
• Production of 500 m3/day of DM Water in
Desalination Plant, by using steam from LP
Turbine
• Design Life : 100 Years
• No exclusion Zone, due to advanced safety
features
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6.
Specifications of AHWR
• Power: 920 MWth, 300 MWe
• Core: Vertical, Pr. Tube; ID: 120 mm
• Coolant: Boiling Light Water
• No. of Coolant Channels: 452
• Fuel Pins: 54 = 24 (Th+Pu) + 30 (Th+U233)
• Fuel Length: 3.5 m
• Core Flow Rate: 2230 kg/s
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7.
Specifications of AHWR
• Coolant Inlet: 259 Deg. Cel.; Outlet: 130 Deg.
Cel.
• Steam Quality: 18.6 %
• Steam Generation Rate: 414.4 kg.
• Steam Pressure: 70 bar
• PSS: 40 Shutoff Rods (Boron Carbide)
• SSS: Liquid Poison Injection in Moderator
• Control Rods: 13
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8.
Specifications of AHWR
• Lattice Pitch: 245 mm
• Discharge Burnup: 24000 MWd/t
• -- up-to 40,000
• Dysprosium is used as burnable poison Dy2O3
in ZrO2
• Natural Dysprosium has 5 isotopes 160 – 164
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9.
Fuel
• 54 pins
– Innermost Ring: 12 Pins (Th233 U)O2, U233 enrichment
3.0 %
– Middle Ring: 18 Pins (Th233 U)O2, U233 enrichment
3.75 %
– Outermost Ring: 24 Pins (Th Pu)O2, Pu
enrichment 2.5% in upper-half & 4.0% in lower-
half
– Central Rod has burnable poison Dy2O3
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10.
Fuel Cluster
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11.
Cross Section of Fuel Cluster
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12.
PHW Reactor Components
• Inlet header
• Feeders
• Coolant Channel
• Outlet feeders called “tail-pipes”
– End-Shield
– Feeder Vault
– Calandria Vault
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13.
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14.
Reactor Structure
• Cylindrical Aluminum Tank: 330cm ID & 500
cm high
• Tank is adequately sized to provide 40 cm D2O
radial reflector around the core
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15.
Calandria Vault
• Concrete block, for shielding
• Two movable shield trolleys, at the top
• Water Filled Reactor Vault Tank, open at top
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16.
General arrangement
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17.
Moderator System
• D2O will be used
• Cover Gas
– Helium
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18.
Instrument & Control
• Neutron (flux) Power measurement
– For reactor regulation and Control
– Detectors are located in Graphite fillers below
Reactor
– In-Core: flux mapping system
• 25 LEU based, fission counters
– Source range monitors: pulse channels
• Conventional Instrumentation
– Flow, Pressure, Temperature & Level
– To generate: ALARM (Hi, V-Hi), TRIP
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19.
Range overlap of channels
Source Range: Pulse Channel
Inter. & Power Range: Six DC Channels
(Multi Range DC Channel: MRDC)
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20.
Shutdown Devices
• Shut-Off rods
– Six: Cadmium (encased in Al) Rods
– 68 mk –ive reactivity addition
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21.
5 AHWR
2
3
6 4
17
1 Secondary Containment
2 Primary Containment
15 3 Gravity Driven Water Pool
8 4 Isolation Condenser
5 Passive Containment Isolation Duct
7 10 6 Vent Pipe
7 Tail Pipe Tower
1 8 Steam Drum
11
9 100 M Floor
9
13 10 Fuelling Machine
11 Deck Plate
12 12 Calandria with End Shield
14
13 Header
14 Pile Supports
15 Advanced Accumulator
16 Pre - Stressing Gallery
16
17 Passive Containment Cooler
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22.
Status
• Structured peer review completed
• Pre-licensing design safety appraisal by AERB
in progress
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23.
AHWR: a quick, safe, secure and proliferation resistant
solution
AHWR is a 300 MWe vertical pressure tube type, boiling light water cooled and D 2O moderated
reactor (A configuration to provide low risk nuclear energy using available technologies)
Major design objectives
 Significant fraction of Energy from
Thorium Top Tie Plate
Displacer
Water Rod
 Several passive features Tube
 3 days grace period Fuel
 No radiological impact Pin
AHWR can be
configured to accept a  Passive shutdown system to
range of fuel types address insider threat scenarios.
including LEU, U-
Pu , Th-Pu , LEU-Th  Design life of 100 years.
and 233U-Th in full Bottom Tie
P late
core  Easily replaceable coolant channels.
AHWR Fuel assembly

24.
PSA Level 3 calculations for AHWR indicate low
probability of impact in public domain
Plant familiarization & Level-3 Atmospheric Dispersion
identification of design With Consequence Analysis
aspects important to
severe accident
Release from Containment
PSA level-1
Identification of
significant events with Level-2 : Source Term (within
large contribution to Containment) Evaluation through
Core Damage Analysis
Frequency
Level-1, 2 & 3 PSA activity block diagram
24

25.
SWS: Service Water
System (63 %)
APWS: Active Process
Water System
ECCS HDRBRK:
ECCS Header Break
SLOCA: 15 %
LLOCA: Large Break
LOCA
Contribution to CDF MSLBOB: Main Steam
Line Break Outside
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Containment 25

26.
AHWR 300-LEU is a 300 MWe system fuelled with LEU-Thorium
fuel, has passive safety features, high degree of operator
forgiving characteristics, no adverse impact in public domain,
high proliferation resistance and inherent security strength.
Peak clad temp. hardly rises even in the complete station blackout and
failure of primary and secondary systems.

27.
Reactor Block components
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28.
Shut Off Rod drive mechanism, Typical Rod-drop
profile
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29.
Main HT System
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30.
Emergency Core
Cooling System
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31.
ECCS
• Passive mode during first 15 minutes, from
accumulators
– 4 Accumulators, 240 m3, Nitrogen at 5.0 MPa
• From Gravity driven water pool for next three-
days (low pressure injection)
– Passivity is obtained by “Fluidic Flow Control
Device”
– 6000 m3 of water
– 4 loops. HX, pump, filter, IX & chemical addition
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32.
Gravity Driven water Pool [GDWP]
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33.
AHWR: Design evaluation by INPRO
method
• IAEA initiated project on, International Project
on Innovative Nuclear Reactors & Fuel Cycles
• Evaluation criteria in six areas
– Economics -- Environment & Sustainability
– Safety -- Waste Management
– Proliferation -- Cross cutting issues
• Reports have been sent to IARA for AHWR
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34.
End of RE – 4 Lecture – 22
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