Flow induced response of thermal insulation and its relation to design

Thermal insulation is fitted in Gas Cooled Reactors to protect vulnerable coolant circuit components from high temperatures. In particular the inner surface of the concrete pressure vessel is lined in the later Magnox stations and in the Advanced Gas Cooled Reactors. The insulated surface area is 1850 m2 in Hinkley 'B' and 3000 m2 in the segregated vessel design used for the Hartlepool and Heysham stations. Extensive on-site erection is needed involving upwards of 300 men for over 18 months. The cost of the insulation is more than 5% of the reactor cost for an AGR station. Once installed, much of the insulation is physically inaccessible and for this reason and because of radiological restrictions the designs fitted must be able to survive in the gas circuit environment for the full reactor lifetime. Should modifications be necessary for any reason, the economic penalty is very high. Constraints on insulation design arising from turbulent flow pressure forces are described and methods for evaluating the insulation vibration response are discussed. (author)