Hmm. My v1.2 (LBB version) states that fission plants provide half the power points, rather than the High Guard rule that they are twice the cost and tonnage.
Using the rules in the basic book a Free Trader would need to install a type B fission plant, massing 3 tons and costing MCr8. Using High Guard, the plant is rated as type A, but is 4 tons and MCr8.
I would say that *neither* printing has been amended, but that the High Guard author assumed or was told that the 2nd printing onward would be.
(Don't get me started on all the errata still to be addressed in v1.2...)