In the last two months, the sixth unit of the „Kozloduy“ NPP has stopped for the second time unplanned, and if we go back a little - three times in total. „This is a completely unusual situation“, said Prof. Georgi Kaschiev.
According to him, the problem has recurred after the major repair of the unit, which was completed on December 1. „After that, for the third time, one of the safety membrane devices of the turbine separator-steam superheater ruptured“, he explained.
Prof. Kaschiev explained that it is a device that has a protective function:
“Their purpose is that if the pressure rises during some transient processes, they release some of the steam, thus reducing the pressure and protecting it from damage.“ These elements are replaced every four years. "There have never been any problems so far," he stressed, adding that original parts from the manufacturing plant in Russia have been used so far.
According to him, in 2024 a public procurement was announced for the supply of original components, the contract was concluded, and subsequently a derogation for import was obtained.
“For unknown reasons, the management of the plant refuses to sign this contract“, said Prof. Kashtiev.
According to him, instead of the original parts, it was decided that they would be manufactured by a Bulgarian company.
“It is very risky to install devices with components that are not approved by the manufacturer. There is an explicit prohibition in a regulatory document. As far as I understand, they refuse to conclude this contract because it seems that they already have an agreement with the company “Energoremont“ in Kozloduy and it to produce these devices, which on the outside look very simple. Very simple, however, for incompetent people, who find it difficult to imagine that this is part of the turbine project, in which years of work and experience of people with different specialties have been invested, studied the experience of operation, etc. If you do not have the same type of material, with the technology from which to produce it, the results can be very sad, as is the case in practice“, the expert emphasized.
He also calculated the financial damage:
„Compared to unit 5, unit 6 has produced about 440 thousand megawatt hours less. If you put an average price of 100 euros per megawatt hour, you get losses of about 60 million euros.“
In his words, these are the “direct and clear damages from this adventurous action“.
Prof. Kaschiev also explained the technical consequences of the repeated stops and starts: “Every unnecessary thermal cycle leads to metal fatigue“ and gave an example: “If you take a piece of sheet metal and fold it, fold it, fold it – on the thousandth attempt it will not bend, but will break.“
Regarding concerns about radiation, he was categorical: “There is currently no risk of radiation.“
But he warned about something else: “If these people calmly violate clear prohibitions in regulatory documents, what is left for their subordinates? This is a degradation of the safety culture.“
According to him, replacement with parts “made of metal similar to the original“ is currently planned. “Similar“, he emphasized, quoting a message on the plant's website.
“They have supplied sheet metal from Chinese manufacturers and hope that its composition is very similar or almost the same as that used in the Russian elements, in the original elements. It will be produced again by the same company “Energoremont“. The technology for preparing this sheet metal, this is 2 mm sheet metal, there is another element in front of it, which according to the factory documentation must be tested in a special stand, how will they do this“, commented Kaschiev.
He also added that there are great risks and great uncertainty.
“It may happen that when increasing the power, already at high levels, the pressure in this component increases, as well as the temperature of the steam. For this reason, they break at high power, already above close to 1000 MW. The same thing may happen again, or the opposite may happen, they are so hard that they do not break at all at such pressure and do not fulfill their design functions. And then such a production accident can happen in the turbine hall that if there is a person around, he will literally be boiled in seconds. This is such a steam flow, it can damage cables, break insulation, not to mention that it can invade places where there are people“, he said.
According to him, this creates new unknowns: “The same thing could happen again. Or the opposite could happen - they could be so hard that they wouldn't break at all under such pressure and wouldn't fulfill their design functions.“
He warned that in such a scenario, a serious production accident could occur in the turbine hall. “Compliance with these requirements is an iron law. This simply does not look like anything“, said Prof. Kaschiev.
At the end of the conversation, he said: “I tell you this with pain, because I spent my youth in these units. Now to see such an attitude simply crosses all limits of irresponsibility.“
The expert also said that invitations have been sent to the Minister of Energy and the management of the “Kozloduy“ NPP to give a public explanation for the decisions taken. In parallel, according to him, signals have already been filed with the prosecutor's office on the case.
“What is happening is, for me, the most blatant outrage here“, the expert believes.