Faculty of Mining, Geology and Petroleum Engineering University of Zagreb
Abstract
The sealing barrier will play very important role in the Czech disposal concept of high level radioactive waste. It follows Swedish SKB3 design where granitic rock environment will host the repository. Swelling clay based materials as the most favorable for sealing purposes were selected. Such clays must fulfill certain requirements (e.g. on swelling properties, hydraulic conductivity or plasticity) and must be stable for thousands of years. Better sealing behavior is obtained when the clay is compacted. Technology of the seal construction can vary according to its target dry density. Very high dry density is needed for buffer (sealing around entire canister with radioactive waste). Less strict requirements are on material backfilling the access galleries. It allows compaction to lower dry density than in case of buffer. One of potential technology for backfilling is to compact clay layers in most of the gallery profile by common compaction machines (rollers etc.) and to spray clay into the uppermost part afterwards. The paper introduces the research works on sprayed clay technology performed at the Centre of Experimental Geotechnics of the Czech Technical University in Prague. Large scale in situ demonstration of filling of short drift in the Josef Gallery is also mentioned.Brtvena barijera će igrati vrlo važnu ulogu u češkom konceptu odlaganja visokoradioaktivnog otpada. Ovaj koncept slijedi švedski SKB3 dizajn u kojem je odlagalište okruženo granitnim stijenama. Kao najpogodniji materijal za brtvljenje odabrani su materijali bazirani na bubrivim glinama. Takve gline moraju udovoljiti određenim zahtjevima (na primjer, značajke bubrenja, hidraulička vodljivost ili plastičnost) i moraju biti stabilne tisućama godina. Bolje brtvljenje postiže se ukoliko je glina zbijena. Tehnologija konstrukcije barijere može varirati prema ciljanoj suhoj gustoći. Vrlo visoka suha gustoća potrebna je za tampon (brtvljenje oko cijelog spremnika radioaktivnog otpada). Nešto su blaži zahtjevi glede materijala za ispunjavanje pristupne galerije. On omogućava zbijanje na nižu suhu gustoću nego u slučaju tampona. Jedna od potencijalnih tehnologija za ispunjavanje je zbijanje slojeva gline u većini profila galerije uobičajenim strojevima za zbijanje (valjci, itd.) i nakon toga prskati glinu u najgornji dio. Članak prikazuje istraživanje tehnologije prskane gline u Centru za eksperimentalnu geotehniku Tehničkog sveučilišta u Pragu. Također je spomenuta „in situ“ demonstracija zapunjavanja kratkog hodnika u Josef Galeriji
