ThorEA - Towards an Alternative Nuclear Future.pdf

Chapter 1: Thorium-fuelled ADSRs and their potential UK and global impact continued
1.4 Why thorium-fuelled ADSRs are an
attractive proposition
There is every possibility that industrialised countries will seek
to decarbonise almost completely their electricity systems by
2040 (or even earlier) through improved energy efficiency,
nuclear energy and growth in renewables. Indeed, such a
scenario is already official UK government policy and the UK
government hopes that other countries will follow a similar
path. Within this scenario there is a clear need to provide
more sustainable nuclear energy technology, and ensure
affordable nuclear fuel in the long term. Broadly speaking, four
sustainable nuclear technology options appear to be available.
Option 1: PUREX reprocessing of LWR spent fuel for
multiple MOX recycling,
Option 2: Moving to critical fast reactors,
Option 3: Commercialisation of nuclear fusion energy,
Option 4: Moving to the thorium fuel cycle.
Option 1 requires a plutonium economy, but might be favoured
by moves away from PUREX techniques and towards more
proliferation resistant and internationalisable approaches.
Option 2, while attractive, remains subject to significant
safety concerns owing to very high core power densities,
short time constants and relatively slow reactor control
response especially in systems with small Doppler feedbacks
(such as are being promoted by the EU).
Option 3, although a long standing goal, remains subject to
significant technical uncertainties.
Included within Option 4 are both conventional critical thoriumfuelled
thermal nuclear reactors and ADSRs. The ADSR has the
benefit that it does not need plutonium or enriched uranium
(U-235) to initiate nuclear power generation in a critical thermal
reactor. So, for example, in an export market there would be no
need to supply fresh Pu-Th fuels to developing countries that are
seeking to develop sustainable nuclear energy.
Amongst the sustainable nuclear fission energy options
the thorium ADSR has a distinct benefit that favours its
internationalisation and widespread deployment. The
thorium ADSR can operate with a once-through fuel cycle.
Fresh fuel can be prepared in a benign and completely
proliferation insensitive forms. No separated or separable
plutonium or U-235 is required at any stage. Spent fuel can
14 Towards an Alternative Nuclear Future
be protected by a particularly strong form of the so called
‘spent fuel standard’. Thorium-fuelled ADSR spent fuel can be
sent for direct disposal without jeopardising sustainability.
ADSR technologies are near-term and sustainable. Compared
to other long-term future options thorium-fuelled ADSR
systems have intrinsically good safety characteristics.
Today raw uranium fuel forms a minor part (roughly 5%)
of the lifetime levelised cost of nuclear power. In the event
of a major global shift to nuclear power, and much sunk
investment in long-lived nuclear power plants, there is a
significant risk that global uranium demand in the 2030s
could begin to exceed supply. Future prospects for uranium
prices could then appear most unattractive when compared
to thorium for ADSR systems.
One might imagine a situation where a uranium fuelled PWR
has a cost base in which perhaps as much as 50% of levelised
costs of electricity are attributable to greatly inflated fuel
prices. Crucially it is worth noting that, EU Sustainable Nuclear
Energy Technology Platform notwithstanding, only one EU
member state is enthusiastic for nuclear fuel reprocessing.
If nuclear power undergoes a significant expansion without
widespread acceptance of reprocessing then uranium prices
will rise very steeply indeed (perhaps by a factor of 10 or
more). It is to avoid such economic risks that a move towards
thorium-fuelled ADSR should be favoured.
In summary thorium-fuelled ADSRs will be:
Technologically more accessible than fusion,
Safer than critical fast reactors,
More internationalisable and proliferation resistant
than reprocessing,
Cheaper than fuelling LWRs with uranium as demand
for fuel begins to exceed supply.
Thorium-fuelled ADSR technology is sustainable
and yet it is consistent with once through fuel
cycles. It is wholly consistent with all UK policy
goals relating to climate change, nuclear power,
reprocessing, and proliferation resistance, and as
such deserves careful consideration as a significant
component of an emerging nuclear strategy.