VT Padmanabhan, R Ramesh, V Pugazhendi

The Belgian nuclear regulator has found a crack in the Reactor Pressure Vessel (RPV) of Deol-3 reactor. The reactor has been closed down for more detailed inspection and it is likely to be shut down for good, 18 years ahead of its scheduled retirement. European Commission has now announced inspection of all RPVs in the member countries.

Likewise, there have been dialogues between the governments of Austria and Czech Republic on the safety of VVER-1000 RPV at Temlin in Czech Republic.

Please also see:
Starting Koodankulam reactor without sufficient backup water would be fatal

RPV has been giving headache to utility owners and regulators for over two decades. If a nuclear power plant is a temple, RPV is its sanctum sanctorum. The vessel made of steel, weighing about 320 tons undergoes a process called embrittlement (in simpler language, premature ageing) due to neutron irradiation in the core region (lower middle part). Indian nuclear scientists might disagree, but IAEA says that a ruptured vessel can turn into missiles and destroy the other two outer containments and spew radioactive poison to the environment. Core catcher, passive heat removal system and all other safety gadgets cannot prevent a catastrophic accident if the vessel breaks.

RPV has been in news in India also. Last week, the Parliament was told that the pressure vessel at Koodankulam had no defect. The minister quoted a certificate given by a committee of 15 government scientists headed by AE Muthunayagam. With all respect to those eminent scientists, we would like to ask which one on them has any expertise and gadgets for inspecting VVER RPV and how did they do it.

Kudankulam RPV has been in the news since the middle of June 2012, when independent scholars asserted that the vessel installed at KKNPP-1 reactor is an obsolete one and susceptible for brittle failure because of welds in the core region. The Atomic Energy Regulatory Board (AERB) responded that the vessels were inspected by their experts and found to be safe and “the evaluation reports (of RPV) cannot be provided in public domain as it contains proprietary details.” Like the site-selection related documentation and the preliminary safety analysis report. One wonders how the safety-related key equipment in an industry owned by the government of India can be the private property of a foreign supplier.

After the Chernobyl accident (1986) and the fall of the Soviet Union, of 30 VVER-1000 reactors under construction in Russia and Eastern Europe were cancelled. Pressure vessels of that vintage have been banned in Europe and Russia since the early 90’s. KKNPP-1 pressure vessel with weld joints in the core region might be one among them.

Installation of RPV is the most important mile-stone in the life of a reactor under construction. In June this year when the vessel was installed in a reactor in China, The World Nuclear News celebrated the event with a banner headline. NPCIL did not celebrate the installation of RPV in 2007. There was no report on this event in the media. Nor is this event recorded in KKNPP timeline on the NPCIL website.

In 2004, NPCIL had dreamt of commissioning KKNPP-1 in 2007, five years after the first pour of the concrete. The Kudankulam reactor vessel arrived at Toothukudi port on Jan 5th, 2005. KKNPP was ready to receive and install the vessel in December 2004 itself. The vessel was installed only after two years of its arrival, quite an uncommon event. In Dec 2006 NPCIL started postponing the commissioning of the plant. A year later, major modifications were also made to the reactor plant. We believe that all these postponements and mid-way modification were needed due to faulty equipments.

At the end of a fuel cycle, the pressure vessel will have 3000 kg of fission products and about 1000 kg of plutonium. Only 80 kg of 137cesium and 131iodine escaped from the Chernobyl reactor in 1986, contaminating the entire land and oceans of the northern hemisphere.

The boys in India are playing their dangerous games on the lives of 300 million people in peninsular India and Sri Lanka with an obsolete technology.