Kursk NPP: How extensive was the damage?

Kursk NPP is located in Kurchatov – a town bearing the name of the prominent Soviet nuclear physicist, and the man behind the Soviets’ A-bomb, Igor Kurchatov. It stands 40 kilometers southwest of Kursk, a large city in Central European Russia, and operates four power units with pressurized-tube reactors with a total capacity of 4 million kilowatts. Last July 22, an incident took place at the plant that put Reactor 1, an RBMK-1000 installation, out of commission and led to what later turned out to be five weeks of ongoing repairs. Even more disturbing, what information was finally made available about the incident did not come through the official channels from the state nuclear corporation Rosatom or Kursk NPP’s head company, the nuclear power plant operator Rosenergoatom, but from Kursk employees.

First, a press release was posted on Rosenergoatom’s website that said little about the incident or its causes. On July 22, 2010, at 12:23 p.m., Reactor 1 of Kursk NPP was scrammed, the message said. The reactor was put under repairs to fix a malfunction in the cooling circuit. The repairs are to take seven days, Rosenergoatom said.

A few routine sentences followed this announcement, which accompany Rosenergoatom’s every incident report, with safety assertions regarding background radiation levels at the plant and in the vicinity and the mention that the incident was classified as a a zero-level, or below-the-scale, event on the International Nuclear Events Scale (INES), i.e. that it had no impact on the safety of the plant or the personnel.

Rosatom’s Crisis and Response Centre – the nuclear industry’s agency responsible for the prevention and handling of emergencies in the field of nuclear and radiation safety – issued a slightly more detailed statement. On July 22, 2010, at 12:23 p.m., the centre said, the reactor’s emergency protection system shut it down following a pressure spike in the reactor core. This was a Type 5 Automatic Emergency Protection event – where the safety system actuates a reduction in the reactor’s power output, taking it down to the lowest level, that is, until the reactor is fully shut down. At the time, the reactor was operating at a capacity of 960 megawatts, the centre reported. The reactor would be under repairs until July 24, 2010, the statement said.

The resulting five weeks – instead of one week – of repairing works testify to the gravity of what happened at Kursk. According to a story that was described in a letter published on the website of the St. Petersburg-based nuclear news agency PRoAtom.Ru, the reactor scram at Kursk occurred as a result of a pressure increase in the reactor core caused by damage sustained by one of the channels of the control and protection system.

Such an accident may put a reactor out of commission for a long time, indeed: Repairing the damaged channel and the graphite moderator blocks effectively means carrying out works that have to be done inside the reactor core. It doesn’t take a nuclear scientist to see the seriousness of the problem – radioactivity levels are through the roof in the core even in a shut-down reactor. If damage occurs to the graphite in the core, the repairs or partial replacement may well be beyond the bounds of the possible and the problem could become an unsolvable one.

Worse, direr consequences are conceivable. Graphite is the dominant feature of the core of an RBMK series reactor. This Russian abbreviation stands for High-Power Channel-Type (or Pressurised-Tube) Reactor and describes a design where graphite is used for the moderation (slowing down) of fast fission neutrons. In essence, an RBMK core is a cylinder-shaped 21-by-21-metre graphite stack 25 metres high, with apertures allowing for both fuel channels (or pressure tubes) and the control channels of the control and protection system. The system is designed to automatically regulate reactor power, keep it at a needed level, and shut down the reactor when necessary. Cooling water is supplied to cool each of the system’s channels.

But this is what has always been Achilles’ heel of RBMK reactors – the very system by which coolant is supplied to the core. If the cooling stops in any one of the control and protection channels, or the flow rate drops significantly, overheating and damage occurs – up to the channel’s destruction and water leaking out onto the reactor’s heated graphite.

Next – a steam explosion and a graphite fire, just like it happened in Chernobyl.

Indeed, it thankfully never got as far as Chernobyl in Kursk on July 22, but if a control channel was destroyed, a discharge of radiation may well have been possible. Nothing to that effect was ever said in any official statements.

Instead, five weeks later, a short statement on Rosenergoatom’s site informed the visitors simply that on August 31, 2010, at 08:50 a.m., “power unit No.1 of Kursk NPP was connected to the grid after completion of repair works. The unit was put in operation in accordance with process procedure requirements for safe operation.”

Was there a radiation discharge?

On August 4, Greenpeace Russia sent a letter to Russian Prosecutor General Yury Chaika, which said: “According to information made available to us, an increase in background radiation levels was picked up by background radiation sensors at the moment the scram was initiated. Our information says one of the control channels of Reactor 1 was destroyed, accompanied with damage occurring to the graphite stack. The likelihood is very high that this could have led to an accidental discharge of some of the radioactive water and a release of radiation beyond the plant’s premises.”

Greenpeace urged the Prosecutor’s office to look into the matter and verify – or disprove – the authorities’ assurances that no consequences implying a release of radiation had taken place during the incident. As of late August, Greenpeace was yet to receive a response from Prosecutor Chaika, or any information at all that would indicate his office had undertaken any investigative steps.

“The prosecutors might have been more effective in their response,” said Vladimir Chuprov, who heads Greenpeace Russia’s energy unit. “What we’re talking about is a possible release of radiation into the surrounding environment, a direct threat to the well-being of the NPP’s personnel and the population of the neighbouring areas. The possibility that radiation [was] still being discharged [as the repairs were under way], cannot be ruled out, either.”

Was a “technological improvement” the underlying cause of the incident?

RBMK-type reactors are highly sophisticated and capricious machines. While no nuclear reactor design can offer an absolute failsafe guarantee of a life-long incident-free operation, RBMKs are specifically reputed to be creatures of fickle character. After the 1986 catastrophe at Ukraine’s Chernobyl Nuclear Power Plant, which employed reactors of exactly this type, enormous funds and studious efforts were invested into modernising the RBMK design and improving its safety record. It may have well been one of these “improvements” that could constitute the underlying cause of the July 22 accident at Kursk.

This is how the nuclear news agency PRoAtom described this improvement:

“During one of the stages of modernisation of pressurised-tube reactors, a new feature was added to the design, whose novelty was that there was no more direct contact between the cooling water used by the control and protection system and the neutron-absorbing rods. The design of this innovation is such that the absorbers move within dry wells contained inside the original control channels and are cooled by the control and protection system’s own cooling circuit. The wells are topped with seals at the channel head.

“This is what allowed for the removal of the main defect of how control rods had originally operated and which had triggered the Chernobyl disaster: Earlier, positive reactivity, or simply, an escalating nuclear reaction, was generated at the initial insertion of control rods into the core from the top end switch, as the displacement of water by the dropping rods precluded normal cooling of the core.

Alas, as it often happens with advantages introduced by a technological innovation, the upsides did not come without the downsides. Less cooling water is allowed into the channels with the new wells installed than it was in the original design, while the level of local resistance to heat removal is higher.”

Why was the reactor not shut down at once?

Further, according to PRoAtom:

The event [at Kursk] was preceded by damage that had several days prior occurred to the well seal in one of the control and protection channels and which resulted in a drastic drop in the water flow rate in the channel. Because of that, less water was available to cool the well. As the cause of the incident was being investigated and the seal changed, the flow of cooling water stopped altogether. This situation remained unchanged for over 24 hours.

The poor circulation of cooling water led to an overheating and rupture of the zirconium tube of the control and protection channel.

It is now anyone’s guess why, given an incident that involved damage of this significance, the reactor was not scrammed at once. Locals in Kurchatov say the plant’s chief engineer wanted to keep generating electricity and shut the reactor down later, so that as little power output was lost during the downtime as possible, and the personnel on site could not disobey the orders, though they foresaw the situation would get worse as things were developing further.

PRoAtom’s story caused a wave of responses by outraged visitors to the website’s forum. If the information is correct about the chief engineer demanding to cut corners in order to continue with power generation, said one guest, then this person must be fired immediately. This incident – or accident, because there was or must have been, in any case, a release of radiation beyond the plant’s perimeters – is nothing but a precursor to a severe accident, that visitor wrote.

“Accidents are not made by politicians or economists or managers – they are made by professionals at their work stations, those who are immediately in charge of the site in question. They are the ones to bear full responsibility in the court of law. Don’t forget [Chernobyl], dear sirs!” the angry post concluded.

A discussion also arose on the forum around whether or not the incident with the poor coolant flow rate was wrongfully ascribed to a faulty flow meter and supposedly unreliable flow readings, and if that was the reason why the reactor was not stopped at once.

Operating a reactor… by sheer guess-work

If PRoAtom’s information is accurate, the incident at Kursk was steadily in the making for at least 24 hours – meaning that certain measures were likely available to qualified staff to stop it developing further. Why weren’t they used? PRoAtom’s forum visitors, most of whom sounded as if they had intimate knowledge of the nuclear industry, with some possibly directly affiliated with Kursk NPP, were able to shed light on that mystery.
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“The RBMKs have been in operation going on 40 years now, and still the Technological Regulations for Reactor Operation allow for equivocal interpretations,” said one visitor. “The limits of safe reactor operation are breached when the rate of water flow in a control and protection channel drops below 2 cubic metres an hour if the rod is inserted. But inserted where – in the channel? In the core? The latest events tell us that even if removed from the core, but inside the channel, a control and protection rod can come under damage in conditions of a poor water flow rate. To top that, no steam at the channel head (if steam is found there, the Technological Regulations provide for an immediate manual scram) can be detected by any technological means, so whatever there was or wasn’t that caused all the fuss, the Central Hall operator who’s looking at this steam, he may not even remember. So the question is, what was the point of investing billions into the reactor’s modernisation if the way we’re still dealing with this quite frequent occurrence is as before – by guesswork?”

“Weren’t there still good reasons to shut the reactor down, if not by the scram button, then it least by power reduction according to regulations? We all know that what’s been happening at the plant, all this time since then, is the melted channel and the rod inside being ‘jimmied out’ [of the reactor]. So, how was it possibly melting without any steam?.. The fact that no steam was mentioned later in accident reports doesn’t mean it hadn’t been there,” another guest said, apparently in response to a suggestion that there hadn’t been grounds enough to shut the reactor down at an earlier point.

“That’s exactly the way things are done,” the same post continued, “by not hearing or seeing anything that doesn’t fit the system. The system’s in a state of a complete meltdown, and you’re still trying to jam facts into it that don’t fit! So you think it was OK to lay all the blame on the flow meter and forget about the control channel until kingdom come? Shame on you! The merits of this approach are self-evident – a total failure. Try to draw some lessons.”

“This is what’s interesting: The alterations were introduced into the design ten years ago. Why would [the Russian industry oversight agency] Rostekhnadzor permit the operation of reactors with such holes in the regulations??” yet another forum visitor wrote.

Kursk’s employees in for a meltdown of their own

According to PRoAtom forum visitors, the all-hands-on-deck emergency repairs and the general disarray have been greatly aggravating the situation in Kursk.

“The [plant’s] management have been forcing operational personnel to carry out radiation-hazardous works, which they made compulsory for them. These people are unprepared to perform such work to begin with, they are not qualified enough, plus all of this is done for no extra pay, during off-hours, and without any papers or documents drawn up… Also, they’ve been bullied by threats to fail them later on some exams like, whatever, industrial hygiene or something, and redundancies for failure to pass. It’s a total mess. Everyone knows Kursk Region is poor and there aren’t many jobs, and the plant pays well enough by comparison, so people are in fear for their jobs, in fear of the bosses… And the bosses are using it as they wish, plugging the holes left by their screw-ups with their employees’ health.”

“They’re making them work overtime and not at their assigned work places, either.”

“What money could compensate for the loss of one’s health? Yeah, keep thinking those thoughts about how radiation is harmless, you fool, when you’re in the repair zone and it’s shining straight at ya with 14 to 16 roentgen per hour. These are the conditions they do their repair work in at the plant,” posted a forum guest in response to another visitor, who had suggested hazard pay was included into the nuclear power plant workers’ compensation, and that the yearly permissible levels or radiation exposure were now anyway lower than they had been in Soviet time.

“Unprofessionalism is when…instead of scramming the reactor, they’ll just log non-existent defects in a perfectly well-functioning coolant flow meter in that channel and go home like it’s no big deal. Those who’ve allowed this accident to happen, they’ve long had a screw or two loose, from all the pressure of achieving high performance rates and being afraid of losing their cushy jobs. And the chances are nil that they’ll get their heads right again any time soon.”

“The event puts this issue on the agenda: Are Kursk NPP’s personnel capable of following the requirements of the Technological Regulations to immediately scram the reactor when emergency situations arise? Or have they been too intimidated and demoralised by all the various reorganisations in the nuclear industry? Intimidated, demoralised, and broken psychologically – this is the main tactic of manipulating personnel at Russian NPPs,” the PRoAtom story concluded.

The unshakable legacy and the sad epilogue

The picture emerging behind these comments – and behind the very story, indeed – is a lamentable one.

Firstly, the so-called “improvements” on the RBMK-1000 design, necessitated as they were by the tragedy at Chernobyl, have led to a common enough solve-one-problem-by-creating-another dilemma: One of the possible causes of the world’s greatest nuclear catastrophe to date may have been safely removed, but the upgrades have given room for the likelihood of other accident scenarios to develop that involve the infamous design. If on July 22 the supply of coolant to the damaged channel were to have been restored, the situation may have well resulted in the destruction of other channels and a steam explosion of a Chernobyl magnitude. The sheer crudeness of the solution chosen to rectify the deficiencies in the old design – turning “wet” control and protection channels into “dry” ones – is nothing short of amazing.

Secondly, the accident put into stark relief the disturbing problem where many reactor parameters that are key to its safe operation – such as steam emerging over a control channel head – are still only detected or assessed with the help of nothing but the naked eye of the operator on duty, and the regulations in place are vague and offer little recourse. This broadens the margin for the possibility of a severer accident already created by the earlier upgrades, by augmenting the risk of errors on the part of the personnel – the notorious “human factor.”

And thirdly, Rosatom, when it became a state corporation, took the worst of what this supposedly free-market form of business management could offer – an unabashed pursuit of profit – and added it to the worst traits it chose to inherit from its predecessor, the Ministry of Nuclear Energy. Its history suggests that little has changed since the ministry, now a corporation operating within a loosely defined legal format, arose in the Soviet Union in the 1950s under the name of Minsredmash. The indecipherable moniker itself – Minsredmash stands in Russian for the Ministry of Medium-Size Machine Building – would be a plain enough hint at how completely shrouded in secrecy the industry was and continues to be, while it never shook off the Soviet-style disregard for the health and well-being of both the nuclear workers and the general population.

And that legacy never shows more clearly than in the public information policies the nuclear industry apparently pursues even today.

Just a few days prior to the incident at Kursk NPP, Rosenergoatom, which regularly reports on “human-interest” events taking place at its branch outfits, wrote of this high achievement at the plant in an August 19 press release (quoted here verbatim):
 
“In 2010 Kursk NPP was declared the award winner of the contest called “100 Best Russian Companies. Ecology and Industrial Safety.” … The enterprise was awarded with a diploma and golden medal. Director of Kursk NPP Nikolay Sorokin was awarded with a badge of honor as “The Best Director in the Field of Environmental and Industrial Safety”. Head of Radiation Safety Department – Head of Environmental Safety Service Aleksey Trubnikov was awarded with a badge of honor as “Environmental Specialist of the Year”.

Kursk NPP became the award winner due to its constant environmental care and continuous investments in the maintaining of the environmental prosperity. The environmental safety system developed by the enterprise helps to detect possible problems and prevent them. The environmental impact of the nuclear power plant does not exceed the set standards. For the last five years state regulatory authorities have detected no violations of the environmental legislation…”

The story continues further with the same copious list of laudatory mentions and stands in sharp – if not outright mocking – contrast both to the unofficial information circulating in the nuclear field’s cyberspace and to the sparse official statements appearing, when and if they do, on incidents that Russian nuclear power plants experience on a regular basis. These are the incidents that force one to take a closer look at safety practices within the industry, and these are also the events that tell one the nuclear industry is in a state of deep crisis. Too bad the politicians and the managers in charge in Moscow keep looking the other way.