atw - International Journal for Nuclear Power | 05.2020

atw Vol. 65 (2020) | Issue 5 ı May
BER II – The End of an Era
Helmholtz-Zentrum Berlin für Materialien und Energie
46 Years in a Nut Shell December 9, 1973 – the day on which the
BER II went into operation. For almost 50 years he shaped the research.
Over the decades, scientists have repeatedly set new research priorities.
Technical developments and political framework conditions also had an
impact on the operation.
Structural research was established at the former Hahn Meitner
Institute with BER II. The new research focus had replaced the previous
focus on nuclear chemistry. It got a decisive boost when the BER II
changed its face again significantly in the early 1990s. The conversion
from 5 MW to 10 MW of reactor output made it possible to establish
international user operations and thus develop research with neutrons in
Berlin on a completely new basis. The BER II became the most modern
device in Germany for experiments with neutron scattering.
Overview of all major milestones
from research with neutrons at BER II
December 9, 1973
The Beginning with 5 MW of Power
| View into the experimental hall.
The planning for the construction of BER II already began in 1966. The aim was to focus on a new branch of research, the structural
research. This increasingly replaced the nuclear chemistry that had previously characterized the experiments at the reactor.
The operation of the predecessor, BER I, was discontinued in 1971.
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RESEARCH AND INNOVATION
1981
Start of Cooperation with the Gemäldegalerie Berlin
Discussions with the Rathgen Research Laboratory of the State Museums and the Gemäldegalerie Berlin started and led to a
long-term cooperation. An experiment site for neutron activation analysis was set up and between 1984 and 1985 nine paintings
by Rembrandt and his school were examined. Dis covering that the “man with the gold helmet” did not originate from Rembrandt
was sensational.
1986 – 1991
Modification of BER II
The first considerations for the conversion were made in 1975; later in 1982 it was an approvable concept. The construction began
four years later. The reactor output was increased to 10 MW and a beryllium reflector was added to the core. This made it possible
to significantly increase the neutron flux. At the same time, a cold neutron source was installed, a pressure vessel in which cryogenic
hydrogen additionally breaks the neutrons. At BER II, slow, so-called cold neutrons could be generated for the first time – a great
benefit for the research.
1991
Restart and Establishment of User Operation
Due to politically determined delays in the approval process, the restart after the renovation took significantly longer than planned.
However, from 1991 on the upgrade made completely new experiments possible. In addition, new experimental stations were
set up to carry out more experiments at the same time. At the same time, the Working Group „Sample Environment“ was established
to support users in their demanding experiments. The foundation for an internationally competitive user company was thus laid.
It was organized in BENSC, the “Berlin Neutron Scattering Center”, which was founded in 1991 as a virtual institute at the HMI.
Within a short time, BENSC had earned an excellent reputation worldwide for its user support.
2000
Conversation to low-enriched uranium
At the turn of the century, reactor operations were switched from
high-enriched uranium (HEU) to low-enriched uranium. The fuel
elements were gradually replaced. In March 2000, a reactor core
went into operation, which was operated for the first time
completely without highly enriched uranium.
2006
Opening of neutron guide hall II
The neutron guide hall II was built from 2004 to 2006. Among
other things, the high field magnet later found its place here.
| View into the neutron guide hall II.
Research and Innovation
BER II – The End of an Era ı Helmholtz-Zentrum Berlin für Materialien und Energie