With the Kudankulam Nuclear Power Project (KKNPP) receiving the crucial nod from the Atomic Energy Regulatory Board (AERB), its first reactor is just one step away from attaining criticality.

The AERB approval was based on the data obtained during the ‘hot run' done last July. KKNPP officials said this has proved the efficiency of every component of the first reactor. It will now be ready for the loading of the enriched uranium fuel assemblies, which will mark the criticality of the reactor that will start generating power from mid-June onwards.

A total of 163 dummy fuel assemblies, each 4.57 metres long and weighing about 705 kg, were loaded into the reactor in April 2010 for full-scale thermo-hydraulic tests of the reactor systems, prior to the loading of actual fuel, to assess the design performance of the systems. The data obtained during these tests were submitted to the AERB for evaluation by its experts.

A high-level team from KKNPP including Site Director, KKNPP R.S. Sundar and Chief Superintendent (Reactors I and II) S.V. Jinna had recently camped in Mumbai for two days to hold talks with experts of the Atomic Energy Regulatory Board on the data obtained during the ‘hot run' and allied results.

Following the deliberations, an immensely satisfied the AERB gave its clearance to open the hemispherical structure on the Reactor Pressure Vessel (RPV) to remove the 163 dummy fuel assemblies. Based on reviews done by the Specialists Groups on Commissioning Aspects (SG-COMM) and Task Force to Review Pre-Service Inspection / In-Service Inspection and the recommendations of the Advisory Committee on Project Safety Review of Light Water Reactors (ACPSR-LWR-1), the AERB granted permission on May 10 for opening RPV Top Head, dummy fuel assembly removal and RPV inspection.

Following the green signal, preliminary works have already been started for opening the RPV and then the dummy fuel assemblies, which may consume a fortnight for its completion.

“Once the dummy fuel assemblies are removed, we'll inspect the RPV once again thoroughly and inform the AERB about the readiness of the first reactor for receiving enriched uranium fuel assemblies. On getting another approval from AERB, we'll start the fuel loading,” Mr. Sundar told The Hindu.