It's a Stross-Dibnah JL-17 nuclear riveting tool. The rivet still has to be inserted from the other side, but there's no need to pre-heat the rivet. The JL-17 applies a type FP-73 micro-tractor beam to pull the rivet tight, before pulse heating it with a fusion torch and mechanically closing the rivet. Type BS-4U countersunk rivets are recommended as they're designed not to fall out while adjacent rivets are closed. So the rivets can be pre-inserted, allowing effective one-man operation. It also knocks down chimneys.