Emergency preparedness is part of a safe operation

Date: 10/03/2010

Since 1 January 2009, the Asse II mine is subject to the provisions of nuclear law. As the operator, the Federal Office for Radiation Protection (BfS) has to ensure the safe operation of the nuclear facility in order to decommission the mine correctly.

Safe Operation

The safe operation of a nuclear facility includes taking precautionary measures which

prevent incidents that make the continued operation of the facility impossible or that stop the correct decommissioning of the facility;

or if this is not possible

reduce the effects of such incidents.

For this purpose a strategic concept was presented for the first time by the Federal Office for Radiation Protection (BfS) on 13 August 2009 and has since been continuously developed further.

Emergency Plans

Saline groundwater has been seeping into Asse II since as early as 1988. As halite and cap rock continue to deform, the possibility cannot be discounted that the inflow of ground water reaches an uncontrollable level. The BfS’ precautionary measures are in particular designed for this case.

The BfS emergency planning covers all plans and measures, which:

reduce the probability that a groundwater inflow reaches an uncontrollable level; and
limit the effects, in case this occurs.

Components and packages of measures

The BfS’ emergency planning breaks down into four components. Individual components comprise of various packages of measures.

Emergency planning components and packages of measures

Preparations for an emergency

An organisational plan in case of an emergency has been developed. Should the mine drown, all additional monitoring measures necessary will be taken.

Measures which prevent the inflow of groundwater into the mine or at lest minimise it, can reduce the risk of an uncontrollable amount of water entering the mine. Such measures, which include sealing drillings, drainage drillings, sealing of hazardous mine openings, are currently investigated.

Even if such measures reduce the risk: They cannot guarantee a short-term and complete safety. It is therefore vital to design the pit in such a way that larger amounts of influent saline solution can be managed.

Actions in this respect are already underway: New storage facilities are set up as well as pipes and pumps installed. A lot of measures have already been implemented or are being prepared. These preventive measures will not hinder the planned retrieval. On the contrary, the retrieval of waste is made possible by such measures.

Reducing the effects of an emergency

Despite of all preventive measures, the possibility that the Asse will drown, i.e. an uncontrollable inflow of saline ground water takes place, cannot be completely eliminated. Therefore, a further component of emergency planning is a number of measures that should reduce the effects of such an incident.

These measures are divided into two phases:

The package of measures “Stabilising the mine openings and protection of emplacement chambers” contains preventive measures which are implemented before the occurrence of an emergency.
The package of measures “Planning, preparation and implementation of the retreat from the pit” contains emergency measures which are carried out in case of an emergency.

Preventive measures

Preventive measures must ensure that as few as possible radioactive material is released should the mine threaten to drown. The preventive measures mainly consist of:

Backfilling of the mine, to reduce the cavity volume and therefore the amount of pollutant or solution pressed out during an emergency
Sealing of redundant mine openings in the vicinity of the emplacement chambers
Retrieval of aerogenic and water-hazardous substances

These must be pre-emptive actions, as there will not be enough time in the event of an emergency.

Pre-emptive measures ease retrieval

Precautionary measures do not threaten the planned waste retrieval. On the contrary, the backfilling of openings stabilises the mine additionally. For example, mine workings situated to the side and below emplacement chambers containing low and medium active waste are pumped full of special concrete. In order to be able to retrieve the waste, chambers above are not filled.

The chambers above are only sealed and filled with concrete in the event of an emergency. Until then waste retrieval is not hampered. In fact, waste retrieval is facilitated through such measures.

Emergency measures

Before emergency measures can be carried out, it must be ascertained that normal operation can no longer be guaranteed (emergency). The responsibility for reaching the conclusion that there is an emergency and neither a safe operation nor a methodical decommissioning can be carried out is with the Federal Office for Radiation Protection (BfS) as the responsible operator in coordination with the competent supervisory authorities according to mining and nuclear law.