INTEGRAL DETERMINATION OF THE BETA AND GAMMA HEAT IN THERMAL-NEUTRON-INDUCED FISSION OF 235U AND 239Pu, AND OF THE GAMMA HEAT IN FAST FISSION OF 238U
The Studsvik Neutron Research Laboratory
University of Uppsala 61182 NYKÖPING SWEDEN
Decay gamma energy and beta energy release rates for thermal neutron fission of 235U and 239Pu and the gamma energy release rates from 238U for neutrons of 2.3 MeV have been measured by integral measurement. The gamma-rays and beta-rays were measured separately in different spectroscopic measurements. Absolute values have been obtained for the 235U gamma energy over the time range 10 s to 1500 s and beta-energy from 10 s to 104 s and for 239Pu gamma- and beta-energy from 10 s to 104 s time, and for 238U gamma energy from 50 s to 104 s cooling time. The accuracy of the data is better than 7 %. Summation calculations for the beta-energy release rates from 235U and 239Pu agree within a few % over the entire time range. Summation calculations gives systematically lower gamma energy at short cooling time. For cooling times around 700 s the discrepancy is about 15 %.
KEYWORDS: Average beta and gamma energies, decay heat, 235U, 238U, 239Pu