Dec 30, 2008. /Lesprom.com/. In the evening of 28 December 2008, there was an explosion in the pipe of the chemical recovery plant at UPM Pietarsaari, Finland, UPM said in a statement received by Lesprom Network. The damages in the pipe have now been evaluated. The explosion did not cause any injuries but caused damages to the lower part of the pipe. Due to the Christmas downtime of the pulp and paper mills, diluted odour gases have been channelled into the pipe instead of the furnace of the recovery boiler. Neither the explosion nor the odour gases caused any environmental damage or damage to people's health. UPM estimates that repairing of the pipe will take 6 days. The estimated cost of the repair is up to Euro 500,000. The start-up of the pulp mill will be delayed until January 4, 2009. The cause of the explosion is still unclear. UPM continues to study the cause of the explosion in coordination with external experts.