Recycling of plutonium of highly burned-up nuclear fuel into the fuel cycle (fuel fabrication)

For a MOX-fuel fabrication plant under German rules and legislation radiation protection aspects are analysed for plutonium recycled from nuclear fuel of high burn-up. Starting form PuO2 powder as the original material, the individual stages of plutonium processing and the related working stations relevant to radiation protection are described in this report. Based on the given plant design and on conservative calculations (compliance with paragraph 54 radiation protection regulation is proven) eighteen plutonium mixtures of differing nuclide composition, corresponding to different plutonium recycle strategies, are examined as to their impact on the radiation exposure during processing. The radiological properties are characterized by simple parameters enabiling straightforward calculations. The calculations are based on radiologically relevant source strengths (100%) of a plutonium nuclide mixture which results from reprocessing of spent uranium fuel of about 32 GWd/tHM burn-up and seven years of ex-core time. Conservative calculations carried out for the given fuel fabrication plant design yield dose rates < 5 mSv/a for most working stations. Radioecological caclulations were carried out for both routine (paragraph 45 radiation protection regulation) and accidental activity releases (paragraph 28(3) radiation protection regulation). Supposing equal routine activity release, the considered plutonium mixtures are covered by the reference nuclide mixture. Caclulations for accidental conditions yield increased doses up to 80%. However, these dose values remain by orders of magintude below the limits as defined by the radiation protection regulation. (orig./HP)