Two pulses of thermal radiation emerge from the fireball. The first pulse, which lasts about a tenth of a second, consists of radiation in the ultraviolet region. The second pulse which may last for several seconds, carries about 99 percent of the total thermal radiation energy. It is this radiation that is the main cause of skin burns and eye injuries suffered by exposed individuals and causes combustible materials to break into flames.

看明白没有？那35%的thermal energy是指的核爆炸后1/10秒产生的紫外线和此后几秒比紫外更长波的可见光线辐射出的热量。核爆炸发生在0.8微秒之内，等那35%的thermal energy出来时，爆炸早完成了，还反射个屁的X-射线。