jeffb was thinking about gas heating when it is compressed and cooling when it is rarefied. But the effect of compression is to allow more efficient cooling by radiation which pulls energy from the plasma (ionized gas). One means of radiation comes from electrons changing direction in the vicinity of other electrons. This is called free-free radiation. Bound states can also be excited by collisions with free electrons and when they radiate that removes energy from the gas. This is called bound-free radiation. I'm not sure if that helps or just baffles further.

An interesting thought. However, it is cooling water, not fuel water so volume and mass situation may be a little different.

Cooling is radiative post-shock. The denser plasma cools more efficiently, proportional to the square of the electron density for a hydrogen plasma cooled by free-free radiation.

There is an omission in the summary, that is a build out by 2050. But, their fig. 8 does have substantially more nuclear power in 2020 than in 2010 and that seems quite unrealistic.

For the US a high Renewable, a high CCS and a high Nuclear scenarios are considered. Look at p. 180 and forward.

There is a problem with the high nuclear scenario in the report. It has a seven fold increase in nuclear power using Gen III reactors but with sea level rise eliminating tidewater sites, there may not be enough cooling available for that large an increase. Nuclear needs extra cooling because it is only about 30% efficient. A number of reactors are shut down already to avoid over heating rivers. Artificial lakes like lake Anna or the South Texas project might work, but you still need a water source to feed them.

The report also explores renewable and carbon capture scenarios so the problem with nuclear may not be a show stopper.

It is actually mid-century, not 15 years for that, but a seven fold increase over 2010 begs the question of where such reactors might be sited. Tidewaters are out owing to sea level rise and rivers are already under heat stress. So, Lake Anna cools not just twelve new reactors to boost its output, but another dozen to cover for Calvert Cliffs? The lake will be boiling.

RTFA: 'the technological paths available for the world's 15 main economies'

RTFA

A portion was left out of the summary. It is by mid-century that we'd see a big change over it the type of generation, not in 15 years. For the US, a renewable heavy, carbon capture heavy and nuclear heavy scenario were looked at. The energy security heavy scenario developed in "Reinventing Fire" by Amory Lovins was not explored. http://www.rmi.org/electricity