By A Gopalakrishnan
19th June 2013 07:23 AM
The Koodankulam Nuclear Power Plant (KKNPP) in Tamil Nadu is owned and will be operated by the Nuclear Power Corporation of India Limited (NPCIL). The Atomic Energy Regulatory Board (AERB) is to oversee and regulate nuclear safety, while the ministry of environment and forests (MoEF) and the Tamil Nadu Pollution Control Board (TNPCB) also have well-defined regulatory roles to play in non-nuclear safety aspects.
Recently, the Supreme Court (SC) reviewed previous lower court judgements and heard fresh affidavits on issues of KKNPP safety. In its final judgment on May 6, 2013, the SC directed AERB, NPCIL, MoEF and TNPCB to (collectively) oversee each and every aspect, including safety of the plant, its impact on environment and the quality of various components and systems in the plant, before commissioning it. The SC has also directed that a (joint) report to that effect be filed before it prior to commissioning of the plant.
To understand the overall problems in their right perspective, one has to see how the total project responsibility at KKNPP is shared between India and Russia. Under the 1998 inter-governmental supplementary agreement, the Russians are to provide the reactor designs and supply the major equipment. The instrumentation and control (I&C) design package, including installation details, were also to come from Russia. The NPCIL and its Indian contractors would build the reactors, but a small team of Russian specialists (“advisers”) would stay at the site to render technical assistance at all stages of construction, in the installation of reactor equipment and in the commissioning and operation of the reactors, until NPCIL takes over.
KKNPP reactors are pressurised water reactors (PWRs) of the Russian VVER type, of 1000 MWe rating. The past Indian experience is entirely on pressurised heavy water reactors (PHWRs), India having built only a very small PWR for a submarine which is yet to be started. The PHWRs are technologically very different from the VVER-1000 reactors, and the Russians have designed and built more than 20 of them. The experience gained over the years by Indian contractors who have steadily worked with NPCIL is also limited to PHWRs. Therefore, it is certainly foolhardy for India to insist that KKNPP Units 1 & 2 shall be built under the above division of responsibilities. The reasons for doing so have been the minimisation of cost and an overconfident estimation of NPCIL’s capabilities, combined with a lack of appreciation of the technological finesse required to build a large and complicated PWR for the first time. The problems described in this article can be primarily attributed to this fatal error in project formulation.
Besides the probable installation of substandard parts in KKNPP reactors due to laxity of quality control, it is now evident that another major safety issue related to the I&C systems is worrying the KKNPP management and the AERB, because of which the Unit 1 start-up is now postponed to July 2013. This inference is reached by piecing together information now available in the public domain. The problem, to put it simply, appears to be the inability to eliminate spurious signals of untraced origin appearing in many of the instrumentation cables of paramount importance to safety, like the reactor neutron chamber output lines, wiring of the safety and shut-off rod control systems, etc.
Such phenomena belong to a broad class of problems known as Electro-Magnetic Interference (EMI). A very rudimentary example of EMI, for instance, is that of a power-carrying, unshielded cable that would generate a surrounding electro-magnetic field, that in turn could induce a voltage/current in a nearby instrumentation or control cable. This spurious input can add to or subtract from the “real” signals, thereby sending erroneous control inputs to a variety of crucial safety systems, possibly leading to unpredictable and serious malfunctions or accidents.
EMI in nuclear plants can be totally avoided by following modern I&C system design and installation norms. (See, for example, “Modern I&C for Nuclear Power Plants”, IAEA, 1999). In particular, obtaining a sound, interference-free transmission of electrical signals between various parts of a nuclear system demands careful attention to cable laying and routing as well as earthing, and requires that specific rules in this regard are strictly followed. The Russian “advisers” on site seem to have earlier indicated to the Indians that most of the VVERs which they have commissioned have used strict Russian standards like GOST 50746-2000, called the National Standard of the Russian Federation for Electro-magnetic Compatibility (EMC) of equipment for nuclear power plants (Requirements and Test Methods), which is available at: http://files.stroyinf.ru/Data1/41/41348/. However, the sequential history of KNPP events do not show that such care was taken in implementation of I&C systems by NPCIL and their contractors.
The cable problems at Koodankulam have a long history. Glimpses of this can be seen from the past annual reports of the AERB. The 2009-2010 AERB report states the regulators were “informed (by NPCIL) that new cable routes have been created to take care of additional cables required for normal operation of the plant, as these were not accounted for in the earlier design”. AERB’s 2010-2011 annual report states that “NPCIL was asked to submit detailed response to various observations made on cable layout — along with justifications for deviations from established methods of laying of cables and alternative measures to meet any exigencies”. Interestingly, the 2011-2012 annual report is totally silent about the follow-up actions taken in this matter.
Around the same time, a telling PTI report on the KKNPP cable problem appeared on July 20, 2011, in Indian newspapers. In part it said (http://ibnlive.in.com/news/tn-kudankulam-nplant-to-achieve-criticality/168957-3.html), “But the observation that several cables were missing, to be incorporated by designers in the reactor almost towards completion of the plant (2009-2010), could not be explained… The designers discovered that several kilometres of power and control cables in the reactor were ‘missed’ after the completion of the double containment of the reactor… A year ago, a major operation had to be undertaken to incorporate the ‘missing’ cables by making new opening in the containment domes (breaking open the concrete walls and its steel liner) and sealing it again after bringing the cables from the switch yard to inside”. One wonders how such a serious error was committed by the NPCIL engineers and their contractors!
This exposes a serious difference in the ethics of doing project site work between the Russians and Indians. Russians are very well-organised and systematic, and they rigidly follow the rules and expect others also to do so. While Indians, too, have rules and regulations on paper, to expedite work or to minimise cost, they would not hesitate to bend or break rules. In case of the I&C design and installation details, the Russians had prepared detailed documentation including hundreds of drawings, which they expected the Indian installers to follow diligently, in the interest of performance and safety. The World Nuclear Association has reported that KKNPP control system documentation was delivered late by the Russians and, when reviewed (http://www.world-nuclear.org/info/Country-Profiles/Countries-G-N/India/#.Ub7fWPkzjAs) by NPCIL, it showed up the need for significant refining and even reworking of some aspects. This was necessitated because, while waiting for details to arrive from Russia, the NPCIL team had proceeded on with the I&C work based on their PHWR experience, little realising that the PWR/VVER requirements contained in the Russian documents would be significantly different. In doing re-work and rectification of the PHWR-based work, the NPCIL team is unlikely to have come close to meeting the Russian design intent or conformed to the installation documents received from them. The origin of the present problem lies in this massive installation error of the NPCIL.
In 2004, the then KKNPP station director told Frontline (http://www.frontline.in/navigation/?type=static&page=flonnet&rdurl=fl2108/fl210800.htm) that “difficulty arose with working documentation, which was to arrive from the Russian designers. But I shall not blame the Russians, there was pressure on them to advance their drawings and documents.” He went on to say, “When you want to speed up…you have to take certain decisions even if the input data are not available. As a designer and an engineer, you have to assume those data and go ahead.” It is this daredevil approach of the NPCIL site engineers and their contractors which has landed the KKNPP in the present mess.
It is most likely that the KKNPP cable system, as completed today, has not conformed to the norms and standards of cable selection, EMI shielding, or layout as per Russian, Indian or any other standards. No wonder the EMI problem is persisting, because there is no other short-cut solution other than re-doing a sizeable part of the I&C cabling and its layout in accordance with a set of modern standards, agreeable also to the Russians. This may take several more months and extensive re-working, but this must be done in the interest of public safety. As directed by the SC, the group consisting of NPCIL, AERB, MoEF and TNPCB must certainly find an acceptable resolution of this problem and include it in their report to the apex court.
A Gopalakrishnan is a former Chairman of India’s Atomic Energy Regulatory Board.
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