Bk. Bylkin et al., Induced radioactivity and waste classification of reactor zone components of the Chernobyl Nuclear Power Plant unit 1 after final shutdown, NUCL TECH, 136(1), 2001, pp. 76-88
The dismantlement of the reactor core materials and surrounding structural
components is a major technical concern for those planning closure and deco
ntamination and decommissioning of the Chernobyl Nuclear Power Plant (NPP).
Specific issues include when and how dismantlement should be accomplished
and what the radwaste classification of the dismantled system would be at t
he time it is disassembled. Whereas radiation levels and residual radiologi
cal characteristics of the majority of the plant systems are directly measu
red using standard radiation survey and radiochemical analysis techniques.
actual measurements of reactor zone materials are not practical due to high
radiation levels and inaccessibility. For these reasons, neutron transport
analysis was used to estimate induced radioactivity, and radiation levels
in the Chernobyl NPP Unit I reactor core materials and structures.
Analysis results suggest that the optimum period of safe storage is 90 to 1
00 yr for the Unit I reactor. For all of the reactor components except the
fuel channel pipes (or pressure tubes), this will provide sufficient decay
time to allow unlimited worker access during dismantlement, minimize the ne
ed for expensive remote dismantlement, and allow, for the dismantled reacto
r components to be classified as low- or medium-level radioactive waste. Th
e fuel channel pipes will remain classified as high-activity, waste requiri
ng remote dismantlement for hundreds of years due to the high concentration
of induced Ni-63 in the Zircaloy pipes.