Some highlights of phase-C commissioning of Tarapur-4 the first to be synchronized 540 MWe PHWR

Commissioning of a Pressurized heavy water reactor (PHWR) plant of NPCIL involves three phases viz phase-A which consist of pre-criticality activities such as hydro test, air hold test, no load test of motors etc., phase-B consist of criticality and post criticality physics experiments. The phase-C, which is considered the major phase, consist of initial power raise to about 10 % , TG rolling, synchronization, going to significant power in steps and performance tests such as load rejection tests from various power levels. In order to have smooth commissioning for the Phase-C, an integrated team consisting of engineers from various design and analysis groups of NPCIL headquarters was formed to participate along with site O and M engineers, closely observe and coordinate phase-C commissioning activities. During this commissioning some major events and observations took place. An attempt is made to bring out the salient observations of Tarapur-4 Phase-C commissioning. This covers various systems and equipment both inside and outside the Reactor Building. An attempt is made to consolidate the lessons learnt from these and bring out the operational issues, which still need attention and resolution. (author)