SMRs are designed to address these concerns. Fuel can be low-enriched uranium, with less than 20% fissile . This low quantity, sub-weapons-grade uranium is less desirable for weapons production. Once the fuel has been irradiated, the mixture of fission products and fissile materials is highly radioactive and requires special handling, preventing casual theft. Contrasting to conventional large reactors, SMRs can without difficulty be adapted to be installed in a sealed underground chamber; therefore, “reducing the vulnerability of the reactor to a terrorist attack or a natural disaster”. New SMR designs enhance the proliferation resistance, such as those from the reactor design company Gen4.These models of SMR offer a solution capable of operating sealed underground for the life of the reactor following installation. Some SMR designs are designed for one-time fueling. This improves proliferation resistance by eliminating on-site nuclear fuel handling and means that the fuel can be sealed within the reactor. However, this design requires large amounts of fuel, which could make it a more attractive target. A 200 MWe 30-year core life light water SMR could contain about 2.5 tonnes of plutonium at end of life. Furthermore, many SMRs offer the ability to go periods of greater than 10 years without requiring any form of refueling therefore improving the proliferation resistance as compared to conventional large reactors of which entail refueling every 18–24 months Light-water reactors designed to run on thorium offer increased proliferation resistance compared to the conventional uranium cycle, though molten salt reactors have a substantial risk. SMR are transported from the factories without fuel, as they are fueled on the ultimate site, except some microreactors. List of reactor designs Numerous reactor designs have been proposed. Notable SMR designs: Proposed sites Canada In 2018, the Canadian province of New Brunswick announced it would invest $10 million for a demonstration project at the Point Lepreau Nuclear Generating Station. It was later announced that SMR proponents Advanced Reactor Concepts and Moltex would open offices there. On 1 December 2019, the Premiers of Ontario, New Brunswick and Saskatchewan signed a memorandum of understanding "committing to collaborate on the development and deployment of innovative, versatile and scalable nuclear reactors, known as Small Modular Reactors (SMRs)." They were joined by Alberta in August 2020. With continued support from citizens and government officials have led to the execution of a selected SMR at the Canadian National Nuclear Laboratory. In 2021, Ontario Power Generation