Rajya Sabha Chairman C P Radhakrishnan on Thursday termed the achievement at Kalpakkam nuclear reactor as a "moment of national achievement over two decades in the making".

The 500-MW Prototype Fast Breeder Reactor (PFBR) at Kalpakkam in Tamil Nadu achieved first criticality on April 6. First criticality is the moment when a nuclear reactor initiates a controlled and sustained chain reaction for the first time.