"Orion Shall Rise"?

Half way through Orion Shall Rise, the slogan has been repeated but we have not yet been told what "Orion" is. However, there have been several clues:

it is a technology prohibited by the Maurai but developed secretly by the Norrmen in a remote mountainous region;

it requires nuclear energy but is not a nuclear weapon;

it will "rise";

when it is tested, there is volcano-like sound and vapour followed by a bright light in the sky and a ship crew expects to be busy;

this is a novel by Poul Anderson and it is not difficult to think of a technology that he would want his characters to develop.

Meanwhile, however, the narrative continues. By (slightly contrived?) means, Anderson has brought two characters from the Federation, two from the Union and two from the Domain together in a Mong wilderness where they will have to cooperate to survive. Thus,we now embark on a passage with further character interaction and some information about survival techniques.