Rethinking energy 3: Advanced nuclear

The Isar nuclear power plant in Germany. New generator designs will allow the nuclear fuel cycle to be closed and nuclear waste to be burned for electricity - turning radioactive waste into a resource. Credit: Wikimedia

LONG-TERM HORIZON
TIMELINE: 2020-2070

THE Sheer SCALE OF shifting to low-carbon energy sources necessitates a third low-carbon baseload option. Even if the intermittency of renewables is addressed with large-scale storage, the substantially lower power density and the uneven distribution of renewable and geothermal energy resources leave a gap that would see power demand outstrip supply as the developing world becomes more industrialised. This third pathway centres around advanced nuclear energy technologies and seeks to address the spike in energy demand coming beyond 2030.

Nuclear energy currently provides 14% of all generated electricity. The 439 reactors now operating in 31 countries provide reliable baseload supplies with almost zero emissions during operation. But there are continuing public concerns: firstly about the creation of long-term radioactive wastes; and secondly about the need for reactor cores to be maintained at a high pressure in order to keep their coolant – water – liquid at high temperatures.

New reactor designs (Generation III, IV and V) offer an increased level of inherent safety. Designs such as that for the Integral Fast Reactor (IFR) also raise the promise of closing the nuclear fuel cycle because they can ‘burn’ most of the high-level nuclear waste, such as reactor-grade plutonium and minor actinides. The system also allows reuse of the waste from earlier generation plants, turning waste from a liability into an energy asset.

A small amount of non-reprocessable waste would still be generated by an IFR. But the scope of the waste management challenge would be substantially reduced to decades rather than tens of thousands of years as currently stands with traditional reactors. To address this, summit participants also reviewed ideas for Generation V reactors such as Thorium-fuelled Accelerator Driven Systems (TADS). These could allow the generation of energy while ‘burning’ or destroying longer-lived waste.

In addition, the reactor remains sub-critical, or unable to sustain a chain reaction without a proton beam activated. Were an accident to occur, the beam could be turned off and the reactor’s core would cease operating immediately.

Both designs use metal coolants that can disperse heat via natural convection; allow the nuclear fuel cycle to be closed and waste to be recycled; and rely on resources – thorium and uranium – that have a high energy density and are abundant on the Earth’s crust. The two reactor technologies are also unsuitable for the development of the fissile material for nuclear weapons, addressing proliferation concerns.

Participants believed Generation IV and V reactors are transformative technologies that could meet the Equinox challenge while allowing an existing problem – nuclear waste – to become a low-carbon energy resource for future generations.

Although both reactor designs have enormous potential, projects to further demonstrate full-scale implementation of these technologies are moving ahead at a snail’s pace. The summit highlighted the need to accelerate progress, pursue whole-system demonstrations and move more rapidly to commercial deployment.

Evolving regulations that foster safety design innovation in next-generation reactors would be essential to realise the potential of advanced nuclear options. In order to leverage the nuclear industry’s innovation capacity, regulations should be reviewed to provide industry incentives for innovation while maintaining strict safety and security standards.

The potential of these reactor designs seems indisputable. But there is a high degree of public scepticism towards nuclear energy that has existed for years and has been exacerbated by the 2011 Fukushima tragedy. Communicating the inherent safety and sustainability of IFR and TADS technologies is challenging. But the Equinox participants didn’t consider this to be insurmountable.

The summiteers proposed a large-scale international collaboration focussed on the development and demonstration of IFR and TADS technologies to demonstrate the benefits of both. This will also require a mobilisation of funding to help address public perceptions.

This is part of a series on a blueprint to address the world’s looming energy crisis.

Rethinking energy: A global blueprint

Rethinking energy 1: Wind and solar coupled with large-scale storage

Rethinking energy 2: Enhanced geothermal energy

Rethinking energy 3: Advanced nuclear

Rethinking energy 4: Organic solar cells for off-grid communities

Rethinking energy 5: Smart urbanisation

Rethinking energy 6: Into the future