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Regional Basic Professional Training Course in Korea

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<strong>Regional</strong> <strong>Basic</strong> <strong>Professional</strong> <strong>Tra<strong>in</strong><strong>in</strong>g</strong> <strong>Course</strong> (BPTC) on Nuclear Safety<br />

and eng<strong>in</strong>eered barriers. Then the mass transfer of disposed radioactive substances <strong>in</strong>to<br />

the host rock will be very low as well. Concrete structures (silos or vaults) and fill<strong>in</strong>g<br />

materials (e.g. cement grout or bentonite) are used as eng<strong>in</strong>eered barriers.<br />

The barrier system for both disposal concepts is quite similar: the conta<strong>in</strong>ment provided<br />

by waste packages, backfill materials and concrete structures, and the retardation capacity<br />

of the host medium. Another important barrier is the chemical conditions provided by the<br />

large amount of concrete <strong>in</strong> the repository; <strong>in</strong> alkal<strong>in</strong>e conditions, some crucial<br />

radionuclides rema<strong>in</strong> immobile. <strong>Basic</strong>ally, the same k<strong>in</strong>d of performance assessment<br />

methods can be used for both disposal concepts. However, scenarios <strong>in</strong>volv<strong>in</strong>g <strong>in</strong>trusion<br />

<strong>in</strong>to the repository have a pronounced role <strong>in</strong> the safety assessments for shallow ground<br />

disposal, while they have m<strong>in</strong>or significance for the long‐term safety of disposal <strong>in</strong>to<br />

bedrock.<br />

In the selection of site for a LILW repository, it may be necessary to take <strong>in</strong>to account a<br />

number of factors: geology, hydrogeology, geochemistry, tectonics, seismicity, climate<br />

and environmental characteristics of the site, demography, transport routes, and nearby<br />

<strong>in</strong>dustrial activities, as well as social aspects. Because the radioactive <strong>in</strong>ventory and<br />

concentrations of long‐lived nuclides <strong>in</strong> LILW are limited, the requirements for the site<br />

characteristics are not particularly high. In addition, eng<strong>in</strong>eered barriers may compensate<br />

for shortcom<strong>in</strong>gs <strong>in</strong> some of the site characteristics.<br />

Prior to the transfer of waste packages <strong>in</strong>to a disposal facility or long‐term storage, their<br />

characteristics must be shown to meet the safety‐related specifications, the so‐called<br />

waste acceptance requirements. These may address the radiological properties<br />

(radionuclide content, external dose rate, surface contam<strong>in</strong>ation, radiolysis potential),<br />

mechanical properties (load and impact resistance, swell<strong>in</strong>g potential, gas generation<br />

potential) chemical properties (corrosion resistance, leach rate, content of free liquids,<br />

combustible materials, complex<strong>in</strong>g agents or chemically toxic materials) and some other<br />

❙ 1038 ❙

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