Moderator temperature coefficient of n value

As shown in Table 1.3, the dependence of n on the neutron temperature is small for 233U and 235U and it has an effect on the order of only 10_5AklklK on the moderator temperature coefficient. Meanwhile, 239Pu has a high dependence and a significant negative reactivity effect of about 10_4 Akl klK on the moderator temperature coefficient. For each individual fissile nuclide, the n value is given by

image091(1.74)

in which the moderator temperature coefficient is expressed as the differ­ence in neutron temperature dependence between the non-1/u fission factor and non-1/u absorption factor, like

Подпись: (1.75)ocj’m аостп ® UtI ^