The report compares running costs of a solar plant against the running costs of nuclear PLUS construction costs. Not only that but also chooses the most expensive plant designs, and takes the extremely high end estimates.
Taken from http://energyfromthorium.com/:
Fuel costs. Thorium fuel is plentiful and inexpensive; one ton worth $300,000 can power a 1,000 megawatt LFTR for a year – enough power for a city. Just 500 tons would supply all US electric energy for a year. The US government has 3,752 tons stored in the desert. US Geological Survey estimates reserves of 300,000 tons, and Thorium Energy claims 1.8 million tons of ore on 1,400 acres of Lemhi Pass, Idaho. Fuel costs for thorium would be $0.00004/kWh, compared to coal at $0.03/kWh.
Capital costs. The 2009 update of MIT’s Future of Nuclear Power shows new coal plants cost $2.30/watt and PWR nuclear plants cost of $4.00/watt. The median of five cost studies of molten salt reactors from 1962 to 2002 is $1.98/watt, in 2009 dollars. The following are fundamental reasons that LFTR plants will be less costly than coal or PWR plants.