Yawancin masu amfani da fission sune masu amfani da wutar lantarki na thermal-neutron wanda ke amfani da mai kula da neutron don jinkirta ("thermalize") neutrons da aka samar ta hanyar fission na nukiliya. Daidaitawa yana ƙara yawan sashi na fission don nucleus fissile kamar uranium-235 ko plutonium-239. Bugu da ƙari, uranium-238 yana da ƙananan ƙananan ƙwanƙwasawa don neutrons na thermal, yana ba da damar ƙarin neutrons don haifar da fission na nucleus fissile da kuma yada halayen sarkar, maimakon a kama su ta hanyar 238U. Haɗin waɗannan tasirin yana ba da damar masu amfani da ruwa mai sauƙi don amfani da uranium mai ƙarancin wadata. Masu amfani da ruwa mai nauyi da masu amfani da graphite-moderated na iya amfani da uranium na halitta koda kuwa waɗannan masu daidaitawa suna da ƙananan ƙarancin ƙarancin ƙwayar neutron fiye da ruwa.
thermal-neutron reactors da suke amfani da neutron moderator don rage gudu