Dealing with Human Intrusion in the Safety Case J9-TM-42929: Technical Meeting to Discuss Human Intrusion and Future Human Actions in relation to Disposal of Radioactive Waste 24 - 28 September 2012, IAEA Headquarters Vienna Dealing with Human Intrusion in the Safety Case - Thomas Beuth -

Content Background Safety Requirements General Information Basic Conditions Approach Potential FHA Case Distinction Potential Impact Potential Detection of Anomalies Stylized HI Scenarios Optimisation Measures Discussion and Results Conclusion J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Preliminary Safety Assessment of the Gorleben Site (PSG) Background Preliminary Safety Assessment of the Gorleben Site (PSG) The objective of the PSG is the evaluation, against the background of previous findings, whether a safe repository is feasible at the Gorleben site. Besides the compilation of existing research results it is of primary concern to identify the needs for future research and exploration and to prepare repository concepts. There are three disposal concepts in terms of heat generating waste: self-shielding disposal casks (POLLUX-, CASTOR-Container) in horizontal drifts transport- and storage casks in horizontal boreholes canisters (fuel rod canister, Triple-Packs) in deep vertical boreholes J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Background (continued) Gorleben Site (Salt Dome in Lower Saxony, Germany) Source: BGR http://www.bgr.bund.de/DE/Themen/Endlagerung/Endlagerstandorte/Gorleben/gorleben_node.html Source: BfS http://www.bfs.de/en/endlager/erkundungsbergwerk_gorleben/geologie/erkundungsbergwerk.html Source: DBETec J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Primary optimisation targets Safety Requirements Primary optimisation targets - Radiation protection for the operating phase - Long-term safety - Operational safety of the final repository - Reliability and quality of long-term waste containment - Safety management - Technical and financial feasibility “5.2 Optimisation of the final repository with regard to reliable isolation of the radioactive materials in the final repository from future human activities shall be carried out as a secondary priority to the aforementioned optimisation targets. As future human activities cannot be forecasted, a variety of reference scenarios for unintentional human penetration of the final repository, based on common human activities at the present time, shall be analysed. Within the context of such optimisation, the aim shall also be to reduce the probability of occurrence and its radiological effects on the general public.” Source: BMU http://www.bmu.de/files/english/pdf/application/pdf/sicherheitsanforderungen_endlagerung_en_bf.pdf J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Safety Requirements (continued) “6.5 For developments associated with unintentional penetration of the isolating rock zone, reasonable risks or reasonable radiation exposure have not been quantified.” “9.7 … For the period after sealing, administrative precautions should be implemented to ensure, as effectively as practically possible, that no human activities which could endanger the permanent containment of the waste are carried out in the vicinity of the final repository. Furthermore, these measures should be designed in such a way that they remain effective for as long as possible in the future.” “10.2 For the period after sealing the final repository, prior to decommissioning, regulations shall be adopted concerning the scope, preservation and accessibility of the documentation to be held on file by the Federal Government by arrangement with the licensing authority. The documentation to be held on file after sealing the final repository must contain all data and documents from the documentation updated during the operating phase which could contain relevant information for future generations. In particular, this should include information regarding the area surrounding the repository mine that must be protected from human intervention in the deep subsoil, and which types of intervention must be subject to special conditions. Complete sets of documents must be stored in at least two different suitable locations.” J9-TM-42929, Dealing with Human Intrusion in the Safety Case

General Information Task Analysis of determined reference scenarios (stylised HI scenarios) related to unintended HI into a repository Objective Optimisation => against HI subordinate to primary optimisation targets (e.g. radiation protection, long term safety, operation safety) reduction of human intrusion potentials reduction of radiological impacts on the general public Definitions Human intrusion (HI) is understood as any human activity following the closure of the repository mine that will directly damage the barriers within the backfilled and sealed mine workings and the isolating rock zone (IRZ). The isolating rock zone (IRZ) is part of the repository system which, in conjunction with the technical seals (shaft seals, cavern sealing structures, dam structures, backfill, … ) ensure containment of the waste. J9-TM-42929, Dealing with Human Intrusion in the Safety Case

b) HI cannot be excluded => logical consequence of a) Basic Conditions a) prediction of FHA is not possible => accepted aspect (general consensus) b) HI cannot be excluded => logical consequence of a) c) occurrence probabilities cannot be derived => logical consequence of a) d) HI has to be considered separately from the systematic scenario development => logical consequence of a) e) only the unintended HI into the repository has to be considered => accepted aspect (broad consensus) f) for developments on the basis of HI, no risks or radiation limits are provided => regulatory provision g) HI scenarios have to be determined on the basis of today’s human activities and today’s techniques => regulatory provision h) it is assumed that HI occurs at the earliest 500 years after repository closure => assumption (due to the expectation that information and knowledge won´t be lost immediately) J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach 1 2 3 4 5 6 7 J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach (Step 1): Potential FHA J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach (Step 2 and 3): Case Distinctions and Potential Impact Cavern Drilling D1 D2 D3 Mine D4 D5 D6 J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach (Step 4): Potential Detection of Anomalies Drilling high wear and abrasion of the drilling equipment (drill bit, boring cutter), changing of the drilling heading as a result of striking the waste cask loss of drilling fluid conspicuities in the debris, drilling core or drilling fluid physical anomalies in the vicinity of the borehole (density, porosity, temperature, natural radioactivity) noticeable differences in the geometry of the borehole (inner width, inclination etc.) Cavern reservoir loss caused by pathways from old mine workings decrease of pressure in case of underground openings from old mine workings pressure peak, caused by e.g. waste casks when slipping or falling into the sump of the cavern structural differences and noticeable objects like waste casks (these can be detected by the common record of the cavern shape and geometry by sonar measurement. Mine high wear and abrasion of the cutting equipment (cutting tool, cutter head) uncovering of the cask surface changing of the drilling heading because of higher or lower drilling resistance detection of dissimilar material physical anomalies towards the driving of heading J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach (Step 5): Stylized HI Scenarios Mine After a comprehensive site exploration and several exploration drillings, which will be partly be converted into transport shafts and ventilation shafts, a mine is constructed in the Gorleben salt dome for the reason of salt production. The mine crosses the IRZ and the emplacement area. The site exploration and the exploration drillings do not lead to the detection of the repository. Today’s common operation times of the mine have to be taken into account as well as the fact that salt mining takes place from upper to lower levels. Cavern After the site exploration and the preliminary exploration drilling, which will be later equipped with respective casings for the solution mining, a cavern is built for storage reasons (crude oil, natural gas, hydrogen, compressed air) or for salt production. The cavern crosses the IRZ completely and therefore also covers the emplacement area. The site exploration and the exploration drilling do not lead to the detection of the repository. For the cavern, today’s common dimensions and operation times have to be taken into account. Drilling A cased exploration drilling is drilled through the Gorleben salt dome and crosses the IRZ but does not lead to the detection of the repository. J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach (Step 6): Potential Optimisation Measures J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach (Step 7): Optimisation Measures J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach (Step 7) (continued): Discussion and Results Drilling Inserting of materials and consideration of a greater cask wall thickness, greater resistance against the drilling heading Inserting of indicators at the exploration level like magnetics and acoustical sensors separation of emplacement areas and emplacement drifts by implementing additional sealings Cavern backfilling of the exploration level with incompressible crushed rock backfilling of drifts at the emplacement level with shaped blocks of granite or basalt inserting of tubes in the host rock (analogous to the planned casings in the borehole concept) inserting of indicators (dyestuffs, olfactory substances etc.) or quality reducing substances Mine inserting of materials and consideration of a greater cask wall thickness to increase the resistance against the driving of heading inserting of indicators (e.g. visual recognition features, olfactory substances) inserting of tubes in the host rock inserting of quality reducing substances Results (only two optimisation measures are feasible) colouring of the backfill or dyestuffs as additives to the backfill inserting of crushed rock at the exploration level J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Approach of dealing with HI in the SC was developed Conclusion Approach of dealing with HI in the SC was developed Basic FHA were identified Consideration of case differentiations Identification of potential detectability of anomalies Determination of HI scenarios Potential optimisation measures against HI Compilation Identification in consideration of HI scenarios Discussion in consideration of primary optimisation targets Inherent measures of the disposal systems depth of the repository wall thickness of disposal casks separation of the waste in different emplacement areas Feasible optimisation measures were identified number of measures are strongly limited finally there is no guarantee that future generations will behave accordingly J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Reference Note: This report will be translated into the English language and is soon available. http://www.grs.de/sites/default/files/pdf/GRS-280_1.pdf J9-TM-42929, Dealing with Human Intrusion in the Safety Case

Thank You! J9-TM-42929, Dealing with Human Intrusion in the Safety Case