SALT Workshop

1. Asse II Mine – Retrieval of waste taking into account the best
possible emergency preparadness
Matthias Mohlfeld, Federal Office for Radiation Protection (BfS), Germany
7th US/German Workshop on
Salt Repository Research, Design and Operation
Washington, DC
September 7-9, 2016
ABSTRACT
The Asse II salt mine near Wolfenbüttel (Germany) is an approximately 100-year-old potash and
salt mine. In early times the former operator used the Asse II mine as a “research mine” for the
disposal of radioactive waste in salt formations. At the beginning of 2009, the Federal Office for
Radiation Protection (BfS) took over operatorship for the Asse II mine. According to a comparison
of possible options for the closure of the Asse II mine, the retrieving of the radioactive waste is,
according to current knowledge, the only option for a safe decommissioning. Therefore, the
decommissioning should take place after retrieving the radioactive waste from the facility.
Retrieving according to § 57 b AtG requires by law the immediate and parallel conduction of
retrieval measures. Necessary are an interim storage facility for the recovered waste, a new shaft
and technology for waste recovery. Investigation for the new shaft started in 2014, retrieval
planning for all types of low-level and medium-level radioactive waste started in 2015. As it is
important to gain relevant data for the planning of retrieval, the exploration and testing phase at
one chamber has been continued in 2016.
Today, the Asse II mine faces two major problems: On the one hand, brines enter the mine, on the
other hand the stability of the mine openings is at risk. Therefore, the BfS has developed actions
for an emergency plan for the Asse II mine. Parallel to the retrieval measures - to improve the
mine’s stability and protect the emplacement chambers as well as to minimise the consequences
of potential flooding – the mine is stabilised by backfilling remaining cavities with concrete.
Additionally, further measures to reduce the radiological consequences of flooding are scheduled.
The emergency plan is maintained and updated on a regular basis. For this purpose, an
accompanying technical examination is carried out on the basis of calculations; experts refer to an
"analysis of consequences". Challenging aspects of these examinations are the enormous amounts
of interactions in regard to content (analysing and updating site conditions) and structure of the
whole project. The Asse II mine is a complex project and, generally spoken, impacts of complex
projects have to be analysed from a system perspective. With its examination, BfS aims to optimise
the developed actions for an emergency plan of the Asse II mine without adversely affecting the
retrievabily.