Structural evolution of containment for Indian Phwrs

Abstract

Pressurised heavy water reactors form the mainstay of the first stage of the Indian Nuclear Power Programme. Each of these units is provided with containment as an ultimate barrier for escape of radioactivity between the inside of the reactor building and the atmosphere. These containments have thus the function of limiting leakage of gases from inside the reactor building to the external atmosphere under the most adverse accidental conditions. To achieve this, beside proper design and construction of containments, suitable energy management features are also incorporated to minimise the pressure and temperature buildup during an accidental condition. Present paper deals with the step by step evolution of containments for Indian PHWRs. This starts from the use of single containment with energy management system based on active components such as dousing system, to a complete double containment with passive energy management system in the form of vapour suppression pool. This evolution is based on design criteria and functional requirements as well as various research and developmental work done in different areas related to containment design. The text initiates the discussion with the brief description of containment systems for different power reactors in India. This is followed by the design criteria and the functional requirements adopted for the containments. Identification of different areas chosen for developmental work and their influence on the design/construction of our containments are described next. It concludes with the indication of future thrust in this area.