The benefits of nuclear energy—dispatchable power with zero emissions (excluding emissions from uranium mining)—are desperately needed in a world facing climate change. The disadvantages of nuclear energy are also great. The old light-water reactors that serve America’s grid today create nuclear waste that’s politically impossible to dispose of. Nuclear plants with traditional reactors are also extremely expensive to build and difficult to permit.

For these reasons, many nuclear hopefuls have looked to advanced nuclear technology. Several startups have popped up, promising to make either the waste problem or the expense problem go away.

This week, two advanced nuclear-technology startups have announced major news, both good and bad for the future of advanced nuclear technology.