Environmental qualification - facilities and case studies

The term environmental qualification is used for assurance or guarantee for satisfactory performance of hardware under specified environmental conditions including normal, abnormal and accident conditions. To generate confidence about satisfactory performance in reasonable time, hardware must be tested under accelerated conditions. For testing and measuring performance parameters, it is essential to have adequate facilities and experienced and inquisitive staff so that qualified and reliable hardware can be manufactured by active participation of manufacturers, users and researchers. Top priority is given to the determination of characteristics, capabilities and limitations of hardware before really starting accelerated testing so that maximum information can be extracted before failure of hardware. This paper describes test and measurement facilities set up at the Bhabha Atomic Research Centre for environmental qualification and some case studies where it has been possible to make significant contributions towards reliability assessment, upgrading and indigenisation. Apart from climatic test facilities (thermal and humidity chambers), a Loss Of Coolant Accident (LOCA) environment simulator and synergistic simulator (combined environment test facility comprising temperature, humidity, gamma radiation and electrical stresses for studying interaction effects) have been set up. Notable case studies are :(1) Assessment of residual life-spans of cables and elastomeric components, (2) Reliability upgradation of indicating alarm meters and solenoid valves, (3) Assessment of survival capability of process instruments under LOCA environment, (4)Assessment of reusability of relays exposed to smoke and water spray in fire incident in a nuclear power station. (author)