A new report by the Radiation Safety Authority (Strålsäkerhetsmyndigheten – SSM) reveals a number of incidents have occurred at the Ringhals nuclear plant in western Sweden, two of which are considered extremely serious.
The latest Category One incident, a classification reserved for the most serious breaches, occurred when an automatic safety mechanism failed to function following the activation of Ringhals’s reactor one in January.
The problem was discovered when the reactor was turned off for an audit in March.
“It’s a function which automatically shuts valves and the like so that radioactive material can’t leave the encasement in the case of an accident, if a pipe bursts, for example. There is also a manual system for that, but if you have an automatic system it should obviously be activated,” said SSM spokesperson Mattias Sköld to the TT news agency.
In late 2008, there was another Category One incident at Ringhals involving the control rods in a reactor.
The rods are used to regulate the activity in a reactor and can also be used to shut activity down quickly.
In all, there have been 60 reported Category One and Two events or security incidents at Ringhals during 2009.
A decision on whether to implement special supervision of the plant is made by the head of Sweden’s radiation agency and is a rarely used measure in its attempt to ensure the safe operation of the country’s nuclear power plants.
“The only case I’m aware of in the history of Swedish nuclear power is Forsmark, where special supervision was stopped a few months ago,” said Sköld.
“Special supervision means that SSM places puts higher demands on audits and investigations so that all types of safety measures are strengthened.”
However the agency stops short of taking over operation and management of the plant.
A final decision on the special supervision of Ringhals will likely be announced in conjunction with SSM’s decision to grant permission to restart reactor one at the plant, which is expected shortly.
But the special supervision would cover the entire plant, not just reactor one.
There have also been several cases in which Ringhals employees have been found to have alcohol or drugs in their blood, although such incidents are not classified by SSM as safety incidents
“Formally, that isn’t something we check. But it’s obviously a part of the general guidelines that people remain sober,” said Sköld.