[en] The Swiss repository concept for long-lived, intermediate-level radioactive wastes (LMA), in Swiss terminology) foresees cylindrical concrete silos surrounded by a ring of granulated bentonite to deposit the waste. As one of the possible options and similar to the repository for high level wastes, the silos will be located in a deep crystalline host rock. Solidified with concrete in steel drums, the waste is stacked into a silo and the silo is then backfilled with a porous mortar. To characterize the release of radionuclides from the repository, the safety assessment considers first the dissolution into the pore water of the concrete, and then diffusion through the outer bentonite ring into the deep crystalline groundwater. For 19 safety relevant radionuclides (isotopes of U, Th, Pa, Np, Pu, Am, Ni, Zr, Mo, Nb, Se, Sr, Ra, Tc, Sn, I, C, Cs, Cl) the report recommends maximum elemental concentrations to be expected in the cement pore water of the particularly considered repository. These limits will form the parameter base for subsequent release model chains. Concentration limits in a geochemical environment are usually obtained from thermodynamic equilibrium calculations performed with geochemical speciation codes. However, earlier studies revealed that this procedure does not always lead to reliable results. Main reasons for this are the complexity of the systems considered, as well as the lacking completeness of, and the uncertainty associated with the thermodynamic data. To improve the recommended maximum concentrations for a distinct repository design, this work includes additional design- and system-dependent criteria. The following processes, inventories and properties are considered in particular: a) recent experimental investigations, particularly from cement systems, b) thermodynamic model calculations when reliable data are available, c) total inventories of radionuclides, d) sorption- and co-precipitation processes, e) dilution with stable isotopes, f) similar chemical behaviour of comparable elements The report compiles the expected maximum concentration in the cement pore water of the inner silo region, together with a detailed description of the criteria leading to the recommended values. For about half of the elements (U, Th, Np, Pu, Am, Ni, Zr, Sr) the presented maximum concentrations have a more general validity in cementitious systems, since they were derived from recent experimental investigations in cementitious environments or from reliable thermodynamic data. For the other elements, the validity of the recommendation is restricted to the specific repository design presented. The recommended numbers strongly depend on particular system properties and must not be transferred to other repository systems. In spite of these short-comings, the underlying criteria are nevertheless applicable to different cement based repositories, and will help to improve the determination of maximum concentrations in such environments. (author)