Abstract

The Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU) intends to establish safety requirements on the disposal of high-level radioactive waste in deep geological formations and to make them binding in a statutory ordinance. Thus, the safety criteria that were published in 1983 by the Federal Ministry of the Interior (BMI) after they had been discussed by the Reactor Safety Commission (RSK), the Commission on Radiological Protection (SSK), and the Federal States Committee for Nuclear Energy, are to be replaced. Against this background, BMU requested Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) in autumn 2006 to develop safety requirements on the disposal of high-level radioactive waste in deep geological formations. They are to form the basis for the proof of safe disposal of the radioactive waste on a site to be determined.

With letters of 16 January 2007 and 21 February 2007, BMU charged RSK and SSK with developing a joint statement on the basis of the GRS report, in particular with regard to the question whether the suggested safety requirements are comprehensible and complete and whether they are in compliance with the state of the art of science and technology, taking into account the international development.

To a large extent, the discussions of RSK/SSK basically showed great approval of the concept proposed by GRS to prove the safety of radioactive waste disposal on a site via the proof of isolation in the isolating rock zone and via the supplementing proof that radiological protection goals in the biosphere are complied with.

The approach of technically defining the isolation effect and, thus, admitting little release, is expressly appreciated by the Commissions. For the proof of isolation appropriate indicators and indicator values need to be established. RSK and SSK could not finally evaluate the proposed indicators and indicator values. However, considerable doubt in the necessity and suitability of individual indicators was expressed. Thus, RSK and SSK consider it urgently necessary to evaluate the proposed indicators, indicator values, and their determination methods with respect to their applicability and handling for different host rocks as well as the probable development and less probable developments. On account of the significance of the indicator values for the proof of isolation and, thus, also for the proof of radiological safety, the Commissions recommend to develop clear provisions for calculating the indicator values.

RSK and SSK support a gradual approach with a number of breakpoints where the proof of safety will be elaborated or up-dated.

With respect to the proposed safety requirements, RSK and SSK recognise the need for improvement in a number of items. Among others, a clear definition of the relevant terms and their consistent use in the text are of special importance.

On account of inherent methodical problems, RSK and SSK do not recommend using values at risk as test values. Currently, it seems to be impossible to consistently evaluate with one standard the potential effects of the radioactive substances and all chemo-toxic substances emplaced in the repository. For all nuclear installations, according to the Radiation Protection Ordinance, the dose is taken as a licensing criterion. Using a risk equivalent, however, is of no advantage regarding the evaluation of exposures due to ionising radiation.

The “Joint Statement by RSK and SSK on the GRS Report ‘Safety Requirements on the Disposal of High-level Radioactive Waste in Deep Geological Formations’” was adopted on the 408th RSK meeting on 9 May 2008 and on the 224th SSK meeting on 3 July 2008.