Political deliberation (until 1989)

In the mid-1980s, the idea of building a "national disposal centre" in the vicinity of the former Federal Institute for Reactor Research (EIR) in Würenlingen started to solidify. While the Confederation wanted to privatise certain institutions involved in disposal, the nuclear power plants brought up the idea of a "central interim storage facility". The local municipality welcomed a private sponsor in the form of a stock company, as this would also bring income for the municipality.

At a general meeting in 1989, the voters of Würenlingen approved the construction of an interim storage facility for radioactive waste in the municipality of Würenlingen (with 214 to 174 votes). This was an exemplary democratic decision driven by strong politicians and businessmen.

In spite of the clear-cut majority at the general meeting, the people opposing the project called a referendum. When voting at the ballot box, the voters of Würenlingen finally approved the contract with 707 yes votes to 662 no votes.

This was followed by many years of emotional debate about the location. In spite of their different opinions, however, the opposing parties always showed their mutual appreciation and relations have remained cordial to date.

Establishment of the company (1990)

Zwilag Zwischenlager Würenlingen AG was established on 18 January 1990 and entered into the Commercial Register on 1 February 1990. The purpose of the company is to operate disposal facilities and provide interim storage capacity for all categories of radioactive waste. The stock company was established by the Swiss nuclear power plant operators at the time (BKW FMB Beteiligungen AG, Kernkraftwerk Gösgen-Däniken AG, Kernkraftwerk Leibstadt AG and Nordostschweizerische Kraftwerke AG).

Approval procedure (1990 to 1996)

After a seven-year approval procedure, the Federal Council approved the construction of the central interim storage facility in Würenlingen and the operation of the storage halls on 21 August 1996. Large volumes of application documents, reports and expert opinions received from various parties were processed during the approval procedure. As the public at that time already had a right to be involved in the procedure, many objections were received, as was to be expected, including some from other countries. The Federal Council and Parliament paid careful attention to all applications, but emphasised that the interim storage facility as a linking pin between the generation of waste and its final storage in deep geological repositories is an important element in the nuclear disposal chain. The nuclear construction and operating permit made it possible to start with this challenging construction project, which was expected to cost around CHF 538 million.

Construction and commissioning of central interim storage facility (1996-2000/2003)

As this was a very big construction project, it could not be handled by individual local companies on their own. Joint ventures were established, some of which are still in existence today. As a result many tasks could be outsourced to local companies, which helped to secure jobs in the region.

The official inauguration took place on 27 April 2000 and was attended by representatives of Swiss business, politics and the energy sector. The facilities were declared ready for operation at a festive ceremony.

The storage hall for low- and medium-level waste was built during a second phase until the end of 2003 and finally put into operation mid 2020.