A filter venting containment system, bearing the acronym FILTRA, will be installed at the Swedish nuclear power plant Barsebäck. The Barsebäck Power Plant is owned by the Southern Sweden Power Supply (Sydkraft AB) and has two 1700-MW boiling water reactors. The reactors are of ASEA-ATOM design with pressure suppression containments (Mark IItype). The installation of the filter venting system is a condition set by the Swedish government for a continued operating license after September 1, 1986. The construction work for the FILTRA plant, the first of its kind ever planned, will be completed at the end of 1985. The FILTRA is designed so that 99.9% of the core inventory of radioactivity, excluding inert gases, is retained in the reactor containment and filter system in the event of containment venting. Another design guideline is to achieve passive functioning of the FILTRA plant during the first 24 h of an accident. The FILTRA plant is common to the two reactors on the site and consists mainly of two systems, a venting system (pressure relief system) and a filtering system. The total cost is approximately U.S. $15 million.