20.08.2015   Nuclear fuel cycle science and engineering

Radioactivity of spent fuel

Overall radioactivity naturally also reflects the isotopic composition of spent fuel. Spent fuel radiation is from three sources of radionuclides:

1 transuranic actinides (the majority of a emitters are in this category and they are also a source of neutrons)

2 fission products (predominantly p-у emitters)

3 activation products from materials of fuel elements other than U pellets (also predominantly p-у emitters)

The total and key isotope radioactivity against spent fuel cooling time is shown in Fig. 15.8 for two fuel burnups.

image170

—■— 5y total

—*— 15y

—•— 60y

— 200y

5y FP

—Д- — 15y

■ — O-■ 60y

-O"

■ 200y

15.7 Decay heat dependence on burnup for various cooling periods showing fission product contributions.3,4
Подпись: Published by Woodhead Publishing Limited, 2012

image172image173

15.8 Effect of cooling time on radioactivity levels of uranium oxide fuel at burnups of 45GWd/tU and 100GWd/tU.