Fast-neutron reactor

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The main features and operating experience of Fastneutron reactors
Report of the student N. Kakhanov
December 3
2018
The first fast neutron reactor
In 1955, the first research fast
reactor of zero power was
launched in the USSR - in the
Physics and energy Institute
(Obninsk) under the leadership of
A. I. Leypunsky. In the same
Institute two years later launched
a research reactor BR-2 with
mercury coolant.
A. I. Leypunsky
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What is fast neutron reactor?
A fast neutron reactor is a nuclear
reactor in which the fission chain
reaction is sustained by fast neutrons.
That means the neutron moderator in
such reactors is undesirable. This is a
key advantage of fast reactors, because
fast reactors have a significant excess
of neutrons, unlike PWRs (or LWRs).
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Scheme of FR
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Breed and Burn (BB) Principles
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Inherent Safety Approach
Superior thermophysical properties of liquid metals allow:
• Operation at high power density and high fuel volume
fraction
• Low pressure operation with significant margin to boiling
• Passive decay heat removal
The fast neutron spectrum leads to long neutron path lengths
• Neutron leakage is enhanced (25% at moderate sizes)
• Changes in power level effects impact the reactor as a
whole, not locally
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Fast reactor operating experience (BN-350)
In the Soviet Union, BN-350 fast
neutron reactor was operated for 25
years. In addition to generating
electricity, BN-350 provided heat for a
desalination plant to produce clean
fresh water from the sea in the
amount of 200 thousand tons per day,
which used about half of its capacity.
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Fast reactor operating experience (BN-600)
− Long-term
tests
of
the
equipment working in sodium
were carried out;
− Operating modes of the power
unit have been worked out and
optimized;
− Technology of replacement
and repair of sodium equipment,
including pumps and steam
generators, has been mastered;
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Fast reactor operating experience (BN-600)
− Obtained a unique experience
in sodium leak, which showed the
effectiveness
of
protective
systems for the localization of the
consequences of leaks;
− Experience of processing of
isotopes of high concentrations;
− The installed capacity usage
time is about 7000 hours per year.
9
Fast reactor operating experience (BN-800)
− BN-800 assumes a transition to
practically non-waste nuclear energy
and the possibility of a wide
expansion of the fuel base;
− It will be used to develop
industrial technologies for the
reprocessing of irradiated fuel and
the manufacture of new fuel
elements (recycling technology);
10
Fast reactor operating experience (BN-800)
− BN-800 has an advanced
protection system. In case of
deviation from the normal mode of
operation, reactor itself shuts down
the nuclear reaction;
− The reactor has an integrated
layout: all the equipment of the
primary circuit exposed to radiation
is enclosed inside its body.
11
Comparison of light water reactor and fast reactor
Characteristics
LWR
FR
786
(U‐235)
556 (Pu
fissile)
Power density (MWt/m3)
102
300
Rod outer diameter (mm)
9.5
7.9
Enrichment (%)
~4.0
~20
40
100
Specific power (kWt/kgHM)
Average burnup (MWd/kg)
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Comparison of light water reactor and fast reactor
Characteristics
LWR
FR
Average linear heat rate (kW/m)
17.5
27.1
pressure (MPa)
15.5
0.1
inlet temp. (°C)
293
350
outlet temp. (°C)
329
500
pressure (MPa)
7.58
15.2
temperature (°C)
296
455
Coolant
Steam
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Conclusion
− FRs have improved neutron
economy;
− FRs can recycle nuclear waste;
− FRs can produce fuel for thermal
reactors;
− FRs liquid metals have superior
heat transfer properties;
− FRs do not use pressure vessel.
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Conclusion
− FRs must use superior control
system;
− FRs can have positive reactivity
feedback from void coefficient;
− Liquid metals require special
technology and handling;
− Fast reactor technology can be
more expensive.
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THANK
FOR YOUR
ATTENTION!
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