There are signs of change in the nuclear reactor market. Finland
is currently evaluating bids for a fifth nuclear unit and Bulgaria
is discussing a new reactor. The U.S. government is funding Nuclear
Power 2010, a program to build at least two nuclear reactors by
2010. The U.S. Department of Energy participates in the Generation
IV International Forum (GIF), an association of ten nations that
seeks to develop a new generation of commercial reactor designs
by 2030.
"New Reactor Designs," a paper from the Energy Information Administration,
summarizes nuclear reactor designs that are available or anticipated
to become available in the United States. The reactors discussed
either are included in the voluntary certification and pre-certification
programs of the U.S. Nuclear Regulatory Commission (NRC) or are
included under the GIF program.
Existing Reactor Designs
All commercial reactors in the United States fall into two categories,
pressurized water reactors (PWR) and boiling water reactors (BWR),
collectively known as light water reactors (LWR). Light water
reactors are the most commercially popular reactor design worldwide.
There have been attempts to operate other classes of reactors
in the United States, including a high-temperature gas-cooled reactor
(HTGR), but most were prototypes and were not commercial successes.
Commercial reactors operating outside the United States include
fast breeder reactors (FBR), pressurized heavy water reactors (PHWR),
and gas-cooled reactors (GCR). FBRs have limited market support,
though units operate in Russia and France.
PHWRs designed by Atomic Energy of Canada Ltd. (AECL), often
called CANDU reactors, have been built in Canada, India, and several
other nations. They are the most successful line of reactors after
the LWRs, and are popular because they can be built and operated
at competitive costs.
GCRs and their derivatives, designed and built since the 1950s
in the United Kingdom and elsewhere, have operated longer than
any other commercial design.
New Designs
Three new reactor designs have been certified by the NRC; all three
are advanced light water reactors that incorporate improved safety
concepts. Only one of the three, the advanced boiling water reactor
from GE/Toshiba/Hitachi, has been deployed, two in Japan and
four under construction in Taiwan and Japan.
Westinghouse BNFL owns the other two certified designs, but no
longer promotes either, in favor of its AP1000, which is presently
the only design undergoing certification.
Several designs are in the pre-certification phase, including
a simplified BWR from General Electric, an advanced BWR from Framatome
ANP that has been bid for the proposed reactor in Finland; and
AECL's ACR-700, an evolution of its CANDU line. Westinghouse BNFL
also has a PWR that would be smaller and much simpler than most
existing PWRs.
Two designs from the HTGR family of reactors, which use helium
for heat transfer, are also in pre-certification--the pebble-bed
modular reactor from Eskom and General Atomic's gas-turbine modular
helium reactor, a design that has received attention as a source
of high temperature heat required for the production of hydrogen.
Two other designs have not been submitted for pre-certification
in the United States but are nevertheless receiving attention,
the European pressurized water reactor and AECL's ACR-1000.
Generation IV Concepts
During 2002, GIF members agreed to concentrate their efforts and
funds on six concept designs that could become commercially viable
between 2015 and 2025.
- The gas-cooled fast reactor uses helium coolant directly to
a gas turbine generator to produce electricity and would be a
breeder reactor. The design might be used as a process heat source
for the production of hydrogen.
- The lead-cooled fast reactor uses molten lead or
a lead-bismuth alloy as its coolant.
- The molten salt reactor
(MSR) involves a circulating
liquid of sodium, zirconium,
and uranium fluorides as
a reactor fuel. The MSR has
been presented as providing
a comparatively thorough
fuel burn, safe operation,
and proliferation resistance.
- Sodium-cooled
fast reactors
have been
the most
popular
design
for breeder
reactors,
with prototypes
built as
early as
1951. Advanced
designs
based on
considerable
additional
research
have a
target
deployment
date of
2015.
- The
supercritical-water-cooled
reactor
is
to
be
the
next
step
in
LWR
development;
it
would
operate
at
higher
temperatures
and
thermal
efficiencies
than
present
LWRs,
and
be
less
expensive
to
build
and
operate
than
today's
LWR.
Most
research
on
the
design
has
been
in
Japan.
- The
very-high-temperature
reactor,
an
evolution
from
the
HTGR
family
of
reactors,
would
operate
at
higher
temperatures
than
other
HTGRs
and
would
provide
process
heat
that
could
be
used
in
hydrogen
production
and
desalinization.
"New Reactor Designs" includes links to supplementary information
about reactor designs and nuclear energy.