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High Temperature Gas-Cooled Reactor (HTGR)
ENGR 5301-35 Nuclear Reactor Kinetics & ControlInstructor
Dr. Wendell C. Bean
The Phillip M. Drayer Department of Electrical Engineering
Fall 2011
Presented by:- Group E
Charanpreet Singh
Karandeep Singh Randhawa
Zaki Ahmed Abbasi
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Outline
Introduction
PC Tran Simulator for HTGR
Simulation Results and Diagrams References
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History of Gas Reactors in US
Peach Bottom (40 MWe) 1967-1974
-First Commercial (U/Thorium Cycle)
-Generally Good Performance (75% CF)
Fort St. Vrain ( 330 MWe) 1979-1989 (U/Th)
-Poor Performance
-Mechanical Problems
-Decommissioned
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Fort St Vrain
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History First proposed by the Staff of the Power Pile
Division of the Clinton Laboratories (knownnow as Oak Ridge National Laboratory) in1947
Professor Dr. RudolfSchulten in Germany alsoplayed a role in development during the 1950s
The Peach Bottom reactor in the United Stateswas the first HTGR to produce electricity
Fort St. Vrain Generating Station was oneexample of this design that operated as anHTGR from 1979 to 1989
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Peach Bottom- First HTGR in US
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High Temperature Gas-cooled Reactor
(HTGR) Also called Very High Temperature Reactor
(VHTR)
Generation IV reactor concept that uses agraphite-moderated nuclear reactor with a once-through uranium fuel cycle
Can conceptually have an outlet temperature of1000C
The reactor core can be either a prismatic blockor a pebble-bed core
The high temperatures enable applications suchas process heat or hydrogen production via thethermo-chemical sulfur-iodine cycle.
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Nuclear reactor design Neutron moderator- graphite. The reactor
core is configured in graphite prismatic blocks
or in graphite pebbles
Nuclear fuel- Coated fuel particles, such as
TRISO fuel particles. Coated fuel particles have
fuel kernels, usually made of uranium dioxide,
uranium carbide or uranium oxycarbide
Coolant- Helium. Helium is an inert gas, so it
will generally not chemically react with anymaterial
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Prototype HTGR generates anywhere from 10MW for an experimental device up to 600 MWper module for a multi-modular power plant
The reactor outlet temperature is in the orderof 700C to 1000C
The helium pressure is from 3 to 8 Mpa
The core helium flow is driven by a circulatorand regulated by variable speed
There are graphite reflectors in both the
annular and central column regions A neutron source is provided for the initial flux
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Operators pull the control rods to reach criticality
Fission energy is transmitted from either
prismatic fuel assemblies or TRISO balls to thehelium coolant
The fuels color changes during its temperature
rise
Heat transfer is by a combination of conduction,
convection and radiation to the containment air
By natural convection of the air and use of
cooling water at heat exchangers secondary side,
heat is removed to the atmosphere
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After reactor shutdown the Shutdown Cooling
System (SCS) is turned on that draws a small
amount of the helium gas from the vesselbottom and cooled by a heat exchanger
In addition to the rod control, the unit power
production can be controlled byBypass valve of the circulating helium flow to
the power conversion unit
Helium temperature controlExtraction and addition of helium
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To reach a given power level
Bypass is the fastest because it directly returns aportion of circulating helium back to the reactor(without going through the power conversionunit)
Temperature control is the slowest because the
large core fuel and moderator heat capacity An extraction valve from the circulating system to
a tank is for extraction and another valve withpump is for pumping helium into the system
A proportional plus integral logic is used tocontrol these valves on the helium pressure
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Since the power conversion system is open to
various designs, a simple pressurized-water
heat exchanger is used for now in thisprototype as heat sink
Super heated steam is generated to drive the
turbine/generator High temperature helium can also be used for
hydrogen production.
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Naturally Safe Fuel
Shut Off All Cooling
Withdraw All Control Rods
No Emergency Cooling
No Operator Action
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Safety features and other benefits The graphite has large thermal inertia. The core is
composed of graphite, has a high heat capacityand structural stability even at high temperatures
The helium coolant is single phase, inert, and hasno reactivity effects.
The fuel is coated uranium-oxycarbide whichpermits high burn-up (approaching 200 GWd/t)and retains fission products
The high average core-exit temperature of theVHTR (1,000C) permits emissions-freeproduction of process heat
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Advantages & Disadvantages of Gas
Cooled Reactors
High Efficiency (45% -50%) Lower Waste Quantity
Higher Safety Margins
High Burnup-100 MWD/kg
Poor History in US
Little Helium Turbine Experience
US Technology Water Based
Licensing Hurdles due to different designs
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Safety Advantages
Low Power Density
Naturally Safe
No melt down
No significant radiation release in accident
Demonstrate with actual test of reactor
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Types of HTGRs Pebble bed reactors (PBR)
The pebble bed reactor (PBR) design consists of fuel inthe form ofpebbles, stacked together in a cylindricalpressure vessel, like a gum-ball machine
Prismatic block reactors (PMR)
The prismatic block reactor refers to a prismatic blockcore configuration, in which hexagonal graphite blocksare stacked to fit in a cylindrical pressure vessel
Both reactors may have the fuel stacked in an annulusregion with a graphite center spire, depending on thedesign and desired reactor power
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What is a Pebble Bed Reactor ?
360,000 pebbles in core
About 3,000 pebbles
handled by FHS each day
About 350 discarded daily
One pebble discharged
every 30 seconds
Average pebble cycles
through core 10 times
Fuel handling most
maintenance-intensive part
of plant
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TRISO Fuel Particle --Microsphere
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Pebble Bed Advantages Low excess reactivity-online refueling
Homogeneous core (less power peaking)
Simple fuel management
Potential for higher capacity factors -no annual
refueling outages
Modularity-smaller unit
Faster construction time -modularity
Indirect cycle -hydrogen generation
Simpler Maintenance strategy-replace vs repair
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AVR in Germany-Pebble Bed
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International Activities
Countries with Active HTGR Programs China -10 MW Pebble Bed -2000 critical Japan -40 MW Prismatic
South Africa -400 MW Pebble -2012
Russia -290 MWe-Pu Burner Prismatic 2007
(GA, Framatome, DOE, etc)
Netherlands -small industrial Pebble
Germany (past) -300 MW Pebble Operated
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Key Technical Challenges
Materials (metals and graphite)
Code Compliance
Helium Turbine and Compressor Designs
Demonstration of Fuel Performance
US Infrastructure Knowledge Base
Regulatory System
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Technology Bottlenecks
Fuel Performance
Balance of Plant Design Components
Graphite
Containment vs. Confinement Air Ingress/Water Ingress
Regulatory Infrastructure
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Simulator-PCTRAN-HTR
PC-based Simulator for High Temperature Gas
Cooled Reactor
Version 0.1 (Beta)
Developed by Micro-Simulation Technology
located at 10 Navajo Court, Montville, New
Jersey 07045, USA
http://www.microsimtech.com/downloads/do
wnload2.asp
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A h t f th PCTRAN HTR
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A screenshot of the PCTRAN HTR
reactor
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PC-based Simulator
For
High Temperature Gas-Cooled
Reactor (HTGR)
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PC TRAN HTGR A prototype PC-based simulator for High Temperature Gas-
Cooled Reactor (HTGR) successfully developed byMicro-Simulation Technology USA.
Using Microsoft Visual Basic language and operates under
Windows operating system.
The input and output are in Access database and its operation
is done by graphic user interface.
Reports and plots can be generated by the program and later
accessed by user.
The run-speed can be used to speed up simulation for 2, 4, 8up to 64 times.
This helps in understanding both the reactor core and the
power conversion system.
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About the Reactor
This prototype can generate anywhere from 10 MW to 600
MW per module for a multi-modular power plant.
The power production can be controlled by
1) bypass valve of the circulating helium flow to the power
conversion unit(fastest way).
2) helium temperature control(slow method). 3) extraction and addition of helium.
A d t b fil
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Access database filesListData.mdb
It has basic plant data and tells us about the status of
control buttons of all initial conditions, heat exchangers,pumps, Trip, malfunctions & gives us a list of initialconditions.
BackData.mdb it contains all backtrack conditions.
OptData.mdb has tables fora:-TimePlotOut which has output time record interval
for PlotData recording.
b:- TimeBackOut which has time interval for writing abacktrack record.
PlotData.mdb stores all the calculated variables in it.
It lists all variable names and their units for plotting. Alsoit has Actual plot data values in it.
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Reactivity
Run-Time
Transient time clock
Heat Exchanger
pump
Hx- capacity
Initial condition no.
Valve
run
Reactor Cavity Cooling
System
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Component Operation P for power control to S for rod control.
Code Control :- Run & Freeze.
Pumps are started and stopped by pressing the left mouse
button when the cursor is on the pump.
Valves can be opened to any position from 0-100% .
Backtrack- can be used to go back to a previous state of
reactor.
Position Dmd-The Rod position can be changed from 0-100%
by it.
Power Dmd- The value of power required at a time can be set
here.
SCRAM- It causes emergency shutdown of the nuclear
reactor by releasing the control rods into reactor core.
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Initial Conditions
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To edit basic data
Data values can be put
manually as-well :-
Gas Pressure(MPa)
Total Fuel Mass(Kg)
Rated Thermal Power(MW)
Avg Fuel Temperature(C)
He Flow Rate (kg/sec)
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Raising Power to 100%
In order to set reactor to give max power
following changes need to be done:-
Rod position needs to be at 89%(withdrawn).
Gas outlet needs to be around 844 C.
Coolant needs to be at 250 C.
Pump for HX 2nd IN needs to be at 100%.
Helium circ pump should be 100%.
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For a Rated Power of 50%
In order to set reactor to work at 50% power
level following changes need to be done:-
Rod position needs to be at 88%.
Gas outlet needs to be around 639 C.
Coolant needs to be at 104 C.
Pump for HX 2nd In needs to be at 63%.
Helium circ pump should be 51%.
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Advantages
Japan and South Africa have been using these simulators fortheir reactors.
All the transient and accident analysis cases are wellreproduced in this simulator.
This PC-based tool can even be used for demonstration of thegas-cooled reactors unique features and its advantages inefficiency and reliability.
Safe characteristic for HTGR can be obtained by it.
The fast run function of PCTRAN up to 64 times faster thanreal-time is valuable in training and analysis.
Reports and plots can be generated by the program and laterprinted by user.
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High Temperature Gas-Cooled Reactor
(HTGR) by Micro Simulation Technology.
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Contents
Introduction1
Simulation
2
Cases3
Click to add Title4
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Transient Verification Runs
Four Cases were selected for PCTRANHTR-10 verification from the followingpaper.
Commissioning and Operation Experience andsafety Experiments on HTR-10
3rd International Topical Meeting on High
Temperature Reactor Technology.
October 1-4, 2006,Johannesburg, South Africa.
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Transient Verification Runs
Model is brought to Critical.
Maintained near 100%Power.
Operating Variables are:
Toutlet = 703.7C
Tinlet = 252.1 C
He Circulation flow = 4.28 kg/sec Core Power = 10 MW
He Pressure = 2.96 MPa
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Design Parameters
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Text
Text
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Case I: He Circulator Trip ATWS Test
Reactor Started at 100% power steady state.
Switch from P to S.
Rod Speed set to zero to prevent its movement.
The He Circulator is tripped without incurring areactor scram.
The transient key plots are follows:
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Case I: He Circulator Trip ATWS
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Case I: He Circulator Trip ATWS
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More Cases
A steady state at 30% power is created forbenchmark of three operational transients.
Rod Withdrawal from 30% power.
Varying Helium Circulation Rate.
Feed water Alterations.
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References
[1] Operation and Control Simulation of a Modular
High Temperature Gas Cooled Reactor Nuclear Power
Plant, Haipeng Li, Xiaojin Huang, and Liangju Zhang ,
IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 55,NO. 4, AUGUST 2008
[2] http://www.microsimtech.com
[3] http://www.cti-simulation.com
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