'Can't stall work at Kudankulam N-plant'

Days after the Tamil Nadu cabinet passed a resolution urging the Centre to stop work at the Kudankulam nuclear power project, the Nuclear Power Corporation (NPC) said technical hurdles will not allow it to stall operations immediately.

A nuclear scientist at the NPC said it was not similar to the shutting down of an automobile plant or switching off power supply and they need to run it to preserve the systems and equipment that have already been set up at the Kudankulam project site.

The nuclear scientist told Business Standard: "NPC has already completed the cooling and chilled water systems. The primary cooling system is ready and tested. Electrical systems are charged and commissioned and the secondary system that includes a nuclear steam supplier system is ready. In a nutshell, pending the fuel loading every thing is complete."

He said the commissioning programme is divided into phases to ensure the completion of all commissioning tests in a logical, safe and effective sequence. The phases include pre-operational tests, hot functional tests without fuel loading and hot functional tests I & II and overall nuclear tests.

The pre-operational tests cover monitoring of trials of all individual equipment, components and systems, including those defined as "construction tests" such as those that ensure proper pump rotation and motor operation. The tests are performance based, mainly for demonstration of the achievement of the proper functions described in the design documents. Commissioning tests of the electrical supply system are performed during this phase, either prior to or in parallel with other system tests.

During Hot Functional Tests I without Fuel Loading the reactor coolant system is operated for the first time together with auxiliary systems. During this phase, the reactor coolant system reaches normal operating pressure and temperature by running the reactor coolant pumps. Plant operation is demonstrated to the extent possible without nuclear steam generation.

The satisfactory completion of these tests is a prerequisite for initial core loading. Further, the hot functional tests II begins with initial core loading. During this phase the reactor is kept sub critical. The hot functional tests continue with the reactor core and complete core instrumentation to demonstrate the operability and safety of the entire nuclear power plant before the start of nuclear operation.

According to the NPC scientist, the plant overall nuclear tests start with initial criticality and then include a step by step approach covering all commissioning tests up to full power testing of the reactor. Within the 0-30 per cent power range, steam is first discharged through the bypass system into the turbine condenser.

After the required steam quality is achieved, the turbine generator is then synchronised and electrical power is fed to the grid. When full power is reached, a number of tests are performed to demonstrate safe and reliable operation of the plant before it is turned over to the operating organisation.