the establishment of a new national energy plan. The Caorso Nuclear Power Plant in Emilia-Romagna, which had been inactive since 1986 due to refuelling, was never reactivated and was finally closed in 1990. The Enrico Fermi Nuclear Power Plant in Piedmont was deactivated in 1987 and shut down in 1990. The construction work on the Montalto di Castro Nuclear Power Station, started in 1982, was interrupted in 1988. The station was converted the following year into a multi-fuel plant. The Latina Nuclear Power Plant was shut down in 1988. The Garigliano Nuclear Power Plant had been shut down since 1978. In 1988, the new National Energy Plan (PEN) established its key objectives: increased energy efficiency, environmental protection, the exploitation of national resources, the diversification of sources of supply from abroad, and the overall competitiveness of the production system. 1990–present: Liberalisation and privatisation Between 1990 and 2000, the Italian electricity market was progressively liberalized. In 1991, Law No. 9/1991 sanctioned a first partial liberalisation of the production of electricity generated from conventional sources and renewable energy sources; companies were allowed to produce electricity for their own use with an obligation to hand over the excess amount to Enel. In July 1992, the Amato I Cabinet turned Enel into a joint-stock company with the Treasury as the sole shareholder. In 1999, the D'Alema I Cabinet issued Legislative Decree no. 79 of 16 March 1999 (known as the Bersani Decree) to liberalise the electricity sector. This opened up the possibility for other actors to operate in the energy market. Enel—which had so far been the only actor in the production, distribution, and sale of electricity in Italy—had now to change its corporate structure by distinguishing the three phases and constituting itself as three different companies: Enel Produzione, Enel Distribuzione, and Terna, respectively, for energy production, distribution, and transmission. Moreover, Enel could produce only 50% of the national production according to the new law. That same year, 31.7% of the company, in its new structure, was privatised. Following privatization, Enel was put on the stock market; its shares were listed on the Italian Stock Exchange with a value of €4.3 per share; the total number was 4,183 million shares for a total value of 18 billion. In this period, Enel was involved in several new projects. In 1993, the company built the Serre photovoltaic plant. At the time, this was largest of its kind