Transcript Slide 1

IAEA CONSULTANCY MEETING ON
INNOVATIVE SMALL NUCLEAR REACTORS
WITHOUT ON-SITE REFUELLING
Development trends, passive safety designs options,
needs for R&D co-ordination
March15-17, 2004
Fixed Bed Nuclear Reactor Concept (FBNR)
Or
A Small Simple IAEA Reactor - ASSIR
Farhang Sefidvash
Federal University of Rio Grande do Sul
Porto Alegre, Brazil
[email protected]
Schematic diagram of the
fixed/fluidized bed nuclear
reactor concept.
(1) structural support; (2) hydraulic
valve opener; (3) fuel discharge
valve; (4) graphite jacket; (5) reactor
core; (6) level limiter shaft; (7)
depressurizer; (8) steam exit; (9) level
limiter drive; (10) fuel feed; (11)
pressurizer; (12) water entrance; (13)
steam generator; (14) level limiter;
(15) absorber shell; (16) hexagonal
channel; (17) fluidization tube; (18)
circular channel; (19) fuel chamber;
(20) distributor (21) entrance
perfurations; (22) coolant entrance;
(23) coolant exit; (24) primary pump;
(25) reflector; (26) biological shield,
(27).fixed bed core, (28) fluidized bed
core, (29) spent fuel pool.
One Module of the Reactor
Some of the Characteristics of the Proposed Reactor
• The Fixed Bed Nuclear Reactor (FBNR) is based on the
pressurized light water reactor (PWR) technology.
• FBNR is simple in design.
• FBNR is a small reactor.
• FBNR is a modular reactor.
• FBNR is an inherently safe reactor.
• FBNR is a passively cooled reactor.
• FBNR is an integrated primary circuit reactor.
• The reactor core is suspended by the flow of water
coolant. The stop in flow causes the fuel elements to
leave the reactor core by the force of gravity.
• FBNR in its advanced version can use supercritical steam
or helium gas as coolant, and may utilize MOX or thorium
fuel. It may also be a fluidized bed nuclear reactor.
Fuel Options
• Two options are proposed:
• 1.
A 8 mm diameter spherical fuel element made of uranium dioxide
with the density of 10.5 g/cm3, cladded by zircaloy and cooled by
pressurized water.
• 2.
A 8 mm diameter spherical fuel element made of compacted
Micro-Fuel-Elements (MFE) with the density of 5.9 g/cm3, cladded by
silicon carbide and cooled by pressurized water.
•
MFE are coated particles and are similar to TRISO fuel with outer diameters about 2 mm. They
consist of 1.5 - 1.64 mm diameter uranium dioxide spheres coated with 3 layers. The inner layer is
of 0.09 mm thick porous pyrolytic carbide (PYC) with density of 1 g/cm3 called a buffer layer,
providing space for gaseous fission products. The second layer is of 0.02 mm thick dense PYC
(density of 1.8 g/cm3) and the outer layer is 0.07 - 0.1 mm thick corrosion resistant silicon carbide
(SiC). Ceramic protection films, manufactured by chemical vapor deposition (CVD) method, create
resistance of graphite components against water and steam at high temperatures (450°- 550° C at
normal operating conditions and up to 1400° C at accidental conditions ). Small fuel elements are
able to confine fission products indefinitely at a temperature less than 1400° C.
Very Small Reactor Option
Core
Level Limiter
Core
core
Fuel Chamber
(high neutron
absorber tube)
Fig. 1: Pressurized water flows upward through the 10 cm diameter fuel
chamber made of highly neutron absorbing alloy. Then it passes through the 25
cm diameter core of the module. After absorbing heat from the core, it passes
through the sieve and an integrated heat exchanger of shell and tube type.
Thereafter, it returns down through the outer space between the tubes back to
the pump and distributor. For detailed description see www.rcgg.ufrgs./fbnr .
Fig.2: Reactor in operating condition. The 8 mm diameter spherical fuel
elements are out of the fuel chamber and are in the core. The core is in
critical condition. The reserve reactivity contains in the extra fuel elements
that are left in the fuel chamber. A fine control rod may be introduced at the
centre of the module should it be necessary.
Fig.3: During shut down or accident conditions. The pump is turned off
automatically, so the fuel elements fall back into the fuel chamber through the
force of gravity.
Fig.4: Shut down condition. The core is empty and the fuel elements are stored
in the fuel chamber in a highly sub critical condition. The decay heat is dissipated
through natural convection.
Small Reactor Option
Core Level
Limiter
Fuel Chamber
(high nêutron
absorber tube)
Fig.5: This option reduces the coolant pressure loss in the fixed bed. The
pressurized water flows upward through the 10 cm diameter fuel chamber made
of highly neutron absorbing alloy. Then it enters the 25 cm diameter core of the
module. It flows up into the perforated central tube and thereafter flows
horizontally through the fuel elements. After absorbing heat from the core, flows
upward passing through an integrated heat exchanger of shell and tube type.
Thereafter, it returns down the outer space between the tubes back to the pump
and distributor. For detailed description see www.rcgg.ufrgs./fbnr .
Fig.6: Reactor in operating condition. The 8 mm diameter spherical fuel
elements are out of the fuel chamber and are in the core. The core is in critical
condition. The reserve reactivity contains in the extra fuel elements that are left
in the fuel chamber. A fine control rod may be introduced at the centre of the
module should it be necessary.
Fig.7: During shut down or accident conditions. The pump is turned off
automatically, so the fuel elements fall back into the fuel chamber through the force of
gravity.
Fig.8: Shut down condition. The core is empty and the fuel elements are stored in
the fuel chamber in a highly sub critical condition. The decay heat is dissipated
through natural convection.
0,28
0,25
0,22
0,19
0,16
0,13
0,1
0,07
0,04
4
3
2
1
0
0,01
Pressure - bars
Pressure Holding the Bed
Coolant Velocity - m/sec
Fig.9: The pressure that holds the fixed bed together as a function
of coolant velocity.
Reactivity of the Reactor
20
15
5
30
35
40
45
50
55
60
65
70
75
80
D=150 Cm
85
-5
95
D=50 Cm
0
0
10
Reactivity - %
10
-10
-15
-20
-25
Core Heigth - Cm
Fig.10: As the fuel elements leave the reactor and the core
height decreases, the reactivity decreases due to the effect
of neutron leakage. Here are variations for the reactor
diameters of 50 and 150 Cm.
70
60
50
40
Power vs. Coolant
Velocity
30
20
10
0,
1
0,
13
0,
16
0,
19
0,
22
0,
25
0,
28
0,
07
0,
04
0
0,
01
Reactor Power - Mw
Power vs. Coolant Velocity
Coolant Velocity - m/sec
Fig. 11: The reactor power produced as a function of
chosen coolant velocity for a 150 Cm diameter reactor.
A coolant temperature rise of 40 C is assumed.
40
30
20
10
0
H=1 m
0,
01
0,
05
0,
09
0,
13
0,
17
0,
21
0,
25
0,
29
Pump power
fraction
Pump power fraction - %
Coolant velocity - m/sec
Fig.12: Pump power fraction needed to pump coolant
through a 1 m height bed as function of coolant velocity.
4
3
2
1
0
0,29
0,25
0,21
0,17
0,13
0,09
0,05
H=0,1 Cm
0,01
Pump power
fraction - %
Pump power fraction - %
Coolant Velocity - m/sec
Fig.13: Pump power fraction needed to pump coolant through
a 0,1 m height bed as function of coolant velocity.
Inherent Safety & Passive Cooling
• The reactor core is suspended by the flow of
water coolant. The stop in flow causes the fuel
elements to leave the reactor core by the force
of gravity and enter the fuel chamber.
• The fuel chamber is a highly subcritical
assembly cooled by natural convection.
• Detection of any signal due to any type of
accident cuts the power from coolant pump.
Waste & Environmental Impact
Its spent fuel is in such a convenient form
and size that may be utilized directly as
the source for irradiation and applications
in agriculture and industry. This feature
results in a positive impact on waste
management and environmental
protection.
Scope of a Co-ordinated Research Project (CRP)
for the constuction of the
PROTOTYPE of the REACTOR
• Preparation of the conceptual design of the chosen
option or options.
• Constuction of a full size non-nuclear hydraulic module
to verify the hydraulics behavior and determine the basic
parameters.
• Realization of neutronics, thermal hydraulics, and
structural calculations.
• Fabrication and testing of the fuel necessary for the
nuclear experiment.
• Engineering design of the prototype of the reactor.
• Performance of a zero power experiment with one
module in a nuclear experimental facility.
• Construction of the single module prototype.
WORK PLAN FOR A
COORDINATED RESEARCH PROJECT
CALCULATIONS
•
Neutronics calculations (utilizing existing PWR
codes chosing spherical fuel option for cross section
calculations).
•
•
Thermal Hydraulics calculations (utilizig modified
PWR codes which may need some verifications).
Structural calculations.
WORK PLAN FOR A
COORDINATED RESEARCH PROJECT
• NON-NUCLEAR EXPERIMENT:
• Construct a full size hydraulic module to observe the behavior of the
dummy fuel elements in the reactor:
•
•
•
•
•
Obtain a 25 and a 10 cm diameter transparent tubes made
from glass or plexiglas.
Obtain 8 mm steel balls commonly used in "ball-bearing"
fabrication.
Obtain a 23 and a 3 cm diameter perfurated transparent tubes.
Provide a flowmeter, a pressure gage, and a control valve.
Measure the pressure loss as a fuction of flow rate and
observe the bahavior of the spheres in the fixed bed by video-taping
the process.
WORK PLAN FOR A
COORDINATED RESEARCH PROJECT
• NUCLEAR EXPERIMENTS:
• FUEL FABRICATION
•
Obtain UO2 pellets used in conventional PWR.
•
Grind the cylindrical pellets to form 8 mm diameter spherical
pellets.
•
Stamp out hemispherical shells from a zircaloy sheet.
•
Press two hemispherical shells against each other with a pellet
between them. Then pass an electric current to weld them together
in an atmosphere of helium at high pressure.
•
Check the helium leakage from the fuel element by a Hedetector to perform quality control.
WORK PLAN FOR A
COORDINATED RESEARCH PROJECT
• NUCLEAR EXPERIMENTS:
• MODULE FABRICATION
•
Obtain a 25 cm diameter zircaloy tube.
•
Obtain a 10 cm diameter stainless steel tube cladded by
highly neutron absorbing materials.
•
Obtain a 23 and 3 cm diameter perfurated zircaloy tubes.
•
Rent a research facility such as LR-0 facility of UJV in
Slovania to perfom full nuclear experiments at zero power
using one reactor module.
WORK PLAN FOR A
COORDINATED RESEARCH PROJECT
ENABLING TECHNOLOGY
•
Conformation of the existing grinding techniques to
transform cylindrical UO2 pellets to spherical pellets.
•
Conformation of the existing welding technology to
clad the spherical fuel elements.
•
Conformation of the existing helium detecting
devices to this particular case.
• Adequation of existing technology to control the flow in a
pump by frequency control, for reactor purposes.
SOME OF THE POSSIBLE
CO-OPERATING INSTITUTIONS
•
•
•
•
•
•
•
•
•
•
•
Imperial College of University of London, England.
University of Calgary, Canada.
University of Pisa, Italy.
Delft university, the Netherlands.
Pacific Northwest National Laboratory, USA.
Prof. Seifritz, Switzerland.
UJV – Nuclear Research Centre of Slovania
COPPE, University of Rio de Janeiro, Brazil.
CDTN & IPEN of CNEN, Brazil
ITEP – Russia
Others
FINANCIAL SCHEME
Government
Researc
h
Centres
Industry
Private
Investors
IAEA
EC
Country
Ci
CRP- IAEA Coordinated
Research Project, the embryo of
WONEC – World Nuclear Energy
Company
The cost of the research and development of a simple one module prototype of
the reactor to demonstrate its feasibility, may be estimated at $1000 000. If at
least 3 European countries take part in the project, the European Community
will contribute with 50% of the cost. Thus what is required is that 5 countries
participate with $100 000 each.
Raising Funds
• Some governments such as Italy contribute with 60% of the cost of
energy projects that are considered to be “clean”. Thus $1.00
investment from indusrry attracts $1.50 from the goverment.
• If 5 (or 10) countries participate: $1.00 investment raises $25 (or
$50.00) for the project.
• Therefore, $1.00 investment from indudtry, research centres, or
private investors raises $25.00 ( if 5 countries) or $50.00 (if 10
countries) for the project.
• The investments can be in the form of service, equipment, or
money.
Suggestion for the approval of the
Consultancy Meeting
• It is recommended that the IAEA nominates a group to
draw up a draft proposal for the constitution of an entity
that may be called the World Nuclear Energy Company
(WONEC) to operate under the auspices of the IAEA.
• WONEC is to be responsible for Research and
Development and finally construction of the innovative
nuclear reactors by drawing on national and international
financial resources worldwide.
• WONEC will provide nuclear energy to all the interested
nations without suffering from adverse effects of nuclear
proliferation.