MOSCOW –The No 6 reactor at the Novovoronezh nuclear power plant in Russia – the first of the country’s flagship AES-2006 series – was taken off the grid due to an electric generator failure, RIA Novosti reported this week.

The incident occurred on November 10, but was not reported by Rosenergoatom, Russia’s nuclear utility, until six days later. The company indicated that the reason for the emergency shutdown of its prize new reactor was a short circuit.

The long delay in reporting the event casts some seeds of doubt over the veracity of Rosenergoatom’s accounting. The closed official lips fed speculation in local media about a looming disaster, which has still not been sufficiently addressed by utility or plant officials.

The incident may represent significant embarrassment for state nuclear corporation Rosatom as well. Just last month Aleksei Likhachev, Rosatom’s new head, touted the reactor as “innovative” and said the new design would be represented in the nuclear fleets of other countries where the company has building contracts.

A view of the plant's machine shop and the repaired generator. (Credit: novnpp.rosenergoatom.ru)

According to Rosenergoatom’s description of events, which appeared on November 16, the reactor went off the grid while tests were being conducted and all emergency systems functioned as expected. The site reported that the incident was a zero on the seven-point International Nuclear Events Scale, zero being insignificant.

“Unit No 6 is in pilot operation and at this stage the reactor is going through a number of tests, and works in various operation modes with the goal of testing new equipment in all possible situations,” Vladimir Povarov, director of the Novovoronezh nuclear plant said on the Rosenergoatom site.

“The failure of specific elements of the equipment is not unusual,” he added. “Our task is the discovery and immediate elimination of all issues.”

The No 6 reactor at the Novovornezh plant is the first of the VVER-1200 series, and its power output is 20 percent higher than its older cousin, the VVER-1000. It was originally assumed that the Novovornezh reactor would go into service in 2012, but there was a four-year delay in its construction.

The reactor began producing energy in August of this year but was brought up to 100 percent capacity only on October 26 as part of field pilot operation. The unit was taken off the grid, having been online at rated capacity for two weeks only.

Environmentalists and other experts have expressed doubts in the reactor’s reliability, performance and untested equipment, and the recent failure would seem to confirm their dubiousness.

Despite the current statement from Rosatom, and the Novovoronezh plant itself, that certain incidents are expected in the testing of their vaunted new reactor, the silence of both for a whole six days following the incident casts doubt on the veracity of official reports on what happened.

The delay led to fearful speculation in a local online publication. On November 15, Bloknot Voronezh posted a report headlined “The consequences of the accident at the Novovoronezh NPP are unpredictable.”

The publication cited an anonymous witness who called the incident “an extraordinary situation” and who talked about an explosion at plant’s turbine hall, and a burned out generator. The witness also mentioned burning electrical equipment and a telltale loud noise.

An anonymous plant source was quoted by the site as saying the noise attributed to an explosion was actually steam pressure valves sharply snapping open.

The source, like the initial RIA Novosti report, said the reactor scram was due to an electric generator failure, and that the reactor would return to tests as soon as the defects that led to the failure were eliminated.

Bellona has sent as-yet unanswered inquiries to the plant about the incident.

On October 27, Rosatom’s Likhachev toured the Novovoronezh plant and praised the new reactor as “especially important” as the first reactor of its kind and hailed its operation at 100 percent capacity as “a big success for Russian atomic technology.”

The flagship VVER-1200 reactor is currently under construction in Belarus. Finland, Turkey, Bangladesh, and Hungary all have orders pending for the reactor.