The principal barriers preventing nuclear power from competing in today’s mix of energy technologies are relatively low efficiency and large scale. Current light water reactor technology tops out at about 34% efficiency, and typical advanced LWR plants cost on the order of $10 billion, which means that few utility companies in the US can afford them. And even small modular LWRs (SMLWRs) are not that small. For one such design, the reactor with its steam generator is more than 25 meters tall, not including the relatively large building for the turbine required to turn steam into electric power. The complexity of such a large structure makes its build time relatively long and its cost potentially high.Reducing reactor size while maintaining high thermal output is the key to better economics.
The Energy Multiplier Module, is being developed by General Atomics. The EM2 is a compact fast reactor about 12 meters high, with 265 megawatts electric (MWe) output. The immediate challenge for the reactor is proving out the fuel element, which consists of novel ceramic cladding and fuel that enable the reactor to operate at high temperatures and high power densities. The company is also developing and testing a compact high-speed turbine generator that can achieve efficiencies of more than 50%.
The typical arguments against more advanced designs are that they will take too long and that the technical risks of fuel and power conversion are high. But what does “too long” mean? Photoelectric materials were discovered in the 1800s, yet we are still working on them. Windmills go back much further in history. Yet neither of those technologies is currently game changing. There are countless other examples. Moreover, due to market conditions, it is unlikely that many LWRs or SMLWRs will be built in the next 10–20 years. So this would be a great time to come up with truly game-changing approaches.
If the energy content from known uranium reserves could be efficiently extracted, it would be 60 times that of known world oil reserves, 50 times the known gas reserves, 20 times the known coal reserves, 260 times the energy from using only LWR technology, or the equivalent of about 90 trillion barrels of oil—400 times the oil reserves of Saudi Arabia. Assuming an oil equivalent of $80 per barrel, the value of known uranium reserves would be $7.3 quadrillion.
It may be time for physicists, the professionals who led the creation of nuclear reactors, to take a hard look at the science of new materials and research on new processes to help continue the development of radically new technologies like those indicated above to provide energy for many centuries.
SOURCE – Physics Today