Abstracts and Available Papers Presented at the 1999 International RERTR Meeting
Conversion of the BER II
A Status Report
(H. Krohn, C.-O. Fischer, K. Haas)
The BER II is a swimming pool reactor and
mainly used for neutron scattering experiments. The BER II has been operating
since 1973, and was upgraded from 1985 to 1991 to increase the neutron flux.
Hereby, the power was increased from 5 to 10 MW. In addition the core size was
decreased and was then encompassed by a beryllium reflector. Finally, a Cold
Source was installed.
When the reactor restarted 1991 with
HEU-fuel, we applied for a license to convert to LEU-fuel, which was granted in
1993. However, we still had to solve the problem of getting rid of our spent
LEU-fuel assemblies. At that time, we also had about 30 HEU-assemblies on
storage. This was the main reason why we only started conversion after August,
1997, when our HEU-fuel was used. At this point, we signed a contract with
US-DOE dealing with the return of the spent fuel assemblies to the USA.
Since then, at each refueling, we have
exchanged 2 to 5 HEU-fuel assemblies by LEU-assemblies. Each time we had to
perform several measurements to ensure for the necessary safety requirements.
These measurements and their results are presented in the