nuclear-news

Russia’s aging nuclear reactors, and the Kola station shutdown

Kola nuclear plant shutdown blamed on deteriorated cable, ending silence on the malfunction, Bellona,  February 11, 2016 by Charles Digges, The cause of a surprise reactor shutdown at Russia’s Kola Nuclear Power Plant’s No 4 reactor on Tuesday was finally explained by the station’s press service as “deterioration of the insulation of a power cable in the course of conducting scheduled tests on an auxiliary systems’ pump.

The initial emergency shutdown of the reactor on Tuesday morning at about 9:37 am Moscow time was originally reported without an explanation – something nuclear experts on Russia said is exceedingly rare, and cause for concern.

The reactor’s age and clearances to run above nominal generating capacity near the city of Murmansk added to worries during the day-long silence on why the No 4 unit had been pulled from the grid……..

To what extent the burnt-out cable represents any threats to safety, however, will only be clear after an investigation by a committee to be appointed by Rostekhnadzor, Russia’s Federal Service for Environmental, Technological and Nuclear Oversight.

According to Andrei Ozharovsky, a Moscow-based nuclear adviser with Bellona, such investigations can be protracted for months, and their results aren’t generally made public.

Worries arose about the sudden, and initially unexplained shutdown because of two aspects in the reactor’s operational history.

First, the reactor, which is a VVER- 440 unit, is running on a 25-year engineering lifespan extension, meaning it will not be taken out of service until 2039, when it’s 60 years old….

Second, the reactor since 2012 has been a part of an experiment to run at various intervals at 107 percent its nominal production capacity. The reactor had also been run at expanded capacities in 1986 and 1987 under Soviet rule, but the Chernobyl disaster of 1986 mothballed that for almost a decade and a half.

Alexander Nikitin, chairman of the Environmental Rights Center Bellona said on Thursday by email that, “it’s not important here how long the reactor has worked or will work – what’s important is that they allowed [such extensions] to begin with.”

As to the experiments in boosting No 4’s power output, Nikitin said, “Difficulties can arise when a reactor is operated at any power, even at the minimum controllable level – but the official decision to stretch the power output and all other corresponding parameters to above normal, of course, adds to risks.”……

The Kola Nuclear Plant’s No 3 reactor in 2011 received 25-year operational extension, pushing its closure back to 2036.

The plant is likewise expecting to get the nod to run the No 3 reactor at boosted power outputs of 104 to 107 percent.

The boosted power regimens are not specific to Russia’s Kola nuclear station. Another six of Russia’s 31 reactors are operating above nominal capacity.

All four of the Balakovo nuclear stations periodically operate at 104 percent, and one of the reactors at the Rostov nuclear plant has clearance to run at 107 percent. http://bellona.org/news/nuclear-issues/2016-02-kola-nuclear-plant-shutdown-blamed-on-deteriorated-cable-ending-silence-on-the-malfunction

February 13, 2016 - Posted by Christina Macpherson | Russia, safety