The Non-Nuclear Conversion of the Montalto BWR/6-Mark III Plant: A Technical and Economical Assessment of the Proposed Options

The 2×981 MW, GE-BWR/6-Mark III Montalto plant was commissioned in the late 1970s by the Italian Public Utility (ENEL), in a context—the “Nuclear Option Plan,” “PUN”¹—which called for the construction of about 10 nuclear powerplants of various types in several sites across Italy, to cover approximately a 15 percent share of the baseload requirements by the year 2000. For several reasons, both technical and political, the ambitious PUN failed, to a point in which, following a National Conference on Energy Generation Systems and Strategies (Feb. 1987), the citizens were called to decide in a national ballot whether they wanted such a plan to be discontinued or enforced (Nov. 1987). The decision having been to discontinue the PUN (by a 66-percent to 34-percent margin), the problem arose about the destination of the two plants which were under construction: “Trino 2”—midway between Torino (Turin) and Milano (Milan)—and “Montalto”—about 70-km from Roma (Rome). Trino, being in the initial construction stages, was promptly halted. The decision about Montalto (70 percent completed) was a more difficult one. Six alternatives were formally presented to a specially appointed Government Committee: (i) the original nuclear option as envisioned by the PUN; (ii) and (iii) two different reconversions to a gas-fired, combined cycle plant, both of which have been proposed earlier (1986) on the basis of objections to the safety procedures related to the reactor’s operation; (iv) a substitution with a series of 7 modular, gas-fired combined cycle plants (also proposed before the national ballot); (v) a reconversion to a multi-fuel, custom-design steam powerplant (also proposed before the national ballot); (vi) a substitution with four modular units, each standard steam multi-fuel (proposed by the Public Utility as the only valid alternative to the completion of the nuclear plant). This paper presents an independent, comparative analysis of the six alternatives, taking into account both technical and economical issues. On the basis of a cost structure deduced by the Public Utility’s published data, an average cost for the kilowatthour is determined for each of the six options, and compared to that corresponding to the completion of the nuclear plant. The final decision of the Italian Government was made public in June 1988 and is also discussed in this final version of the paper.