Radioactivity release and dust production during the cutting of the primary circuit of a nuclear power plant: The case of E. Fermi NPP L. Bonavigo a, * , M. De Salve a , M. Zucchetti a , D. Annunziata b a Politecnico di Torino, Dipartimento di Energetica, corso Duca degli Abruzzi, 24,10129 Torino, Italy b SOGIN S.p.A., Centrale Nucleare di Trino, ss31 bis, 13039 Trino (VC), Italy Keywords: Decommissioning PWR Trino Vercellese NPP Cutting techniques abstract This paper concerns the cutting operations and spread of radioactive contamination during the dismantling of a nuclear metal component, carried on with thermal cutting. Our analysis relates to E. Fermi nuclear power plant (Trino Vercellese, Italy), a Pressurized Water Reactor, which had an elec- trical power of 272 MWe, and was in operation from 1965 to 1987. The plant included four primary loops and a pressurizer, each loop equipped with a circulation pump and a steam generator. The criteria for choosing between all the cutting technologies available for dismantling a nuclear component are considered, as well as the methodology allowing the characterization of the primary system. Some cutting scenarios are proposed, with a calculation methodology to evaluate the amount of material involved in main components segmentation. Afterwards, exposition risks are highlighted and the possibility of safely cutting this system is pointed out. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction The selection of segmentation technique for the various components of a nuclear plant is one of the operational neces- sities of decommissioning. To choose the ideal technology, some criteria must be considered: costs, occupational risks, kind of material, geometry, accessibility, presence of radioactivity. A wide range of dismantling techniques, both mechanical and thermal, are developed and tested during decommissioning of plants (Cumo et al., 2002; Eickelpasch et al., 1997; Klein et al., 2001; Steiner et al., 1997), often supported by European Community research programmes. Dismantling work is often carried out by external contractors, presumably not experienced with the facility working conditions. Besides concrete, metal will constitute the most part of solid materials resulting from a plant decommissioning. This will be divided into: material for releasing (solid material containing traces of radioactivity lower than the free release level), contam- inated not releasable material, or activated not releasable material. The destiny of such material should be planned with an eye toward clearance, recycling and reuse of all components and scraps (Anigstein et al., 2001; IAEA, 2004, 2000; NEA, 2008; Nieves et al., 1998). The primary system cutting activity implies the dealing with contaminated and activated metals. Some of material classification reference criteria useful to plan its processing are reported in Table 1 . The necessity of reducing external dose in not remote cutting activities suggests choosing high velocity techniques, in order to reduce workers exposure time. On the other hand these techniques, like plasma cutting, produce more secondary waste than other methods. The resulting metal dusts can be inhaled; this inhalation per se produces damage; moreover it causes pathologies like respiratory syndrome or chromosome damage (Gurzau et al., 2003; Jelmert et al., 1994; Malo and Chan-Yeung, 2009; Rana, 2008). In addition to these risks, internal radiation exposure via inhalation can occur. A certain radiological risk shall be considered for workers. There is a large variety of dismantling techniques that are state of the art and in use. They can be grouped into mechanical (sawing, shearing, milling, diamond wire sawing, pipe-cutting.), usually used for activated component cutting, thermal (oxy-fuel cutting, lance cutting, plasma-arc cutting, laser beam cutting.) and hydraulic (water jet cutting, abrasive water jet cutting) (EPRI, 2008, 2007, 2005, 2001, 2000). When applied underwater, radiation protection is improved while visibility on the cutting area is reduced (IAEA, 1999). The particle size distribution of the resulting aerosol and the quantity of dust that can be collected during cutting depend on various factors: cutting technology, cutting parameters, measurement point, aeration, kind of material, environmental conditions (Bromaan et al., 1994; Dua et al., 2000). Generally, * Corresponding author. Tel.: þ39 011 5644495; fax: þ39 011 5644499. E-mail address: lucia.bonavigo@polito.it (L. Bonavigo). Contents lists available at ScienceDirect Progress in Nuclear Energy journal homepage: www.elsevier.com/locate/pnucene 0149-1970/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.pnucene.2009.07.009 Progress in Nuclear Energy 52 (2010) 359–366