[T]he report’s executive summary certainly gets to the heart of their findings.
“The rhetoric from small modular reactor (SMR) advocates is loud and persistent: This time will be different because the cost overruns and schedule delays that have plagued large reactor construction projects will not be repeated with the new designs,” says the report. “But the few SMRs that have been built (or have been started) paint a different picture – one that looks startlingly similar to the past. Significant construction delays are still the norm and costs have continued to climb.”
What makes you think it’s less efficient. Normally high temperature reactor technology is more efficient not less.
I’m not claiming to be any more knowledgeable than what I read here, but Wikipedia says
https://en.wikipedia.org/wiki/Thorium-based_nuclear_power
In 1973, however, the US government settled on uranium technology and largely discontinued thorium-related nuclear research. The reasons were that uranium-fuelled reactors were more efficient, the research was proven and thorium’s breeding ratio was thought insufficient to produce enough fuel to support development of a commercial nuclear industry