someone forgot move the decimal point on their slide-rule?
The Shrimp device tested in Bravo was a 15 Mt two stage thermonuclear surface burst. This was the first “dry” or solid fuel (lithium deuteride fueled) H-Bomb tested by the U.S., and the first solid fuel Teller-Ulam device ever tested. It was the largest bomb ever tested by the U.S. although this was by accident. The yield of Bravo dramatically exceeded predictions, being about 2.5 times higher than the best guess and almost double the estimated maximum possible yield (6 Mt predicted, estimated yield range 4-8 Mt).
The Shrimp test device was basically a scaled down version of the Runt device tested in Castle Romeo, but with partially enriched lithium as fuel. Its weight was a comparatively light 23,500 lb, and it was 179.5 in long and 53.9 in wide. The fuel consisted of 37-40% enriched lithium-6 deuteride encased in a natural uranium tamper. 10 Mt of the yield was from fast fission of the tamper. The Shrimp also tested light case design, substituting an aluminium exterior case for the steel used in the Sausage (tested in Ivy Mike). It used a RACER IV fusion boosted primary.
The reason for the unexpectedly high yield was due to the “tritium bonus” provided by the lithium-7 isotope which made up most of the lithium. This isotope was expected to be essentially inert, but in fact it had a substantial reaction cross section with the high energy neutrons produced by tritium-deuterium fusion. When one of these high energy neutrons collided with a lithium-7 atom, it could fragment it into a tritium and a helium atom. Tritium was the most valuable fusion fuel, being both highly reactive and causing extremely energetic fusion, so this extra source of tritium greatly increased the weapon yield.