[en] To approach the subject of high level nuclear waste disposal in deep ocean sediments it is convenient to differentiate between processes occurring in a near field environment, that region arbitrarily defined as lying between the canister surface and the maximum extent of the 100⁰C isotherm, and those which occur at lower temperatures and beyond the influence of intense radiation. A variety of considerations related to the chemistry of seawater-sediment mixtures suggests that about 200⁰C is the maximum temperature advisable in the near field environment. Results of a coupled fluid flow - thermal transport computer model show the maximum convection rate adjacent to a canister having surface temperature of 200⁰C is 0.3 m/100 years, and that this velocity is halved with the passage of each thermal half life of the assumed waste form (30 years). Based on this convective model, it follows that compounds formed in the near field environment during the first thousand years following emplacement would be restricted to a region lying within two meters of the canister surface