<br />Biggest US nuke tested was 'Mike' and it hit 15 megatons (unexpectedly, I might add, too, the scientists thought Li7 would dilute the fuel, not enrich it) and USSR set off one at around 57 megatons (Kruschev claimed more but he may have been misinformed by some one trying to look better). 57MT device was a 2/3 scale test of 100 MT design, so they came pretty close on their 'proof of concept'. Pure fission bombs tough to make large, but fusion bombs (with their staged fission, fusion, fission design courtesy of Ulam, et al) apparently can be made very large indeed. I have never seen an upper limit described, and the 'dry' design of Mike (and presumably the Soviet one, too) are surprisingly compact. If you wanted to build a nonmobile one, don't see any limit in size other than getting initial fission trigger hot enough to 'light the match', so to speak. Some world governments may find these attempts disturbing so confine your experiments to the thought variety and please don't assemble any hardware in your garage. Think Clarke described GT range bombs in some of his fiction, and I've always thought he was more sci than fi in his writing. <br /><br /><br /><br />Work can be very rewarding. You should try it.<br />Dilbert <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>