Corus appeared at Swansea crown court on 14 December to plead guilty to two charges of failing to ensure the safety of workers and contractors contrary to sections 2(1) and 3(1) of the Health and Safety at Work Act 1974. Both offences related to its operation of a blast furnace at its Port Talbot site.
The Health and Safety Executive said the incident exposed a "systemic corporate management failure". Corus had long recognised serious faults with the blast furnace but failed to act on recommendations for improvements.
On the morning of 7 November 2001, workers carried out repairs to a transformer supplying power to water pumps that circulated cooling water around the furnace. The work tripped the pumps, which cut the water flow for several minutes and caused three coolers to burn out and leak water into the furnace.
There had been no prior communication between maintenance and blast furnace staff over the work and the pump’s power supply was not monitored during the repairs.
The leak was not detected until the evening, by which time 50-60 tonnes of water had entered the furnace, causing the molten material to start to solidify. Lack of experienced staff and poor cooling equipment design hampered efforts to find the leak.
If the furnace continued to be chilled by the leaking water it would shut down, leading to substantial financial consequences.
Attempts to restore the liquid flows within the furnace by manually injecting oxygen did not solve the problem. Further water leaks were increasing concern about the furnace’s safety.
At 4pm on 8 November, production staff held an emergency meeting to discuss the situation. The main concern was the risk of a liquid metal break-out through the vents which blast hot air into the furnace.
But the risks of a much more serious explosion were not recognised. Safety staff were not present at the meeting and the company had no procedures for dealing with the situation.
The explosion occurred at 5.15pm when water came into contact with molten metal in the furnace. The force lifted a large section of the furnace off the ground, expelling molten metal and gas into nearby rooms where employees were working.
The HSE told the court that an explosion of this type and size within a blast furnace was unprecedented and Corus could not have foreseen it. However, the dangers of water and molten material coming into contact outside the furnace are well known. The prosecution gave three examples of such incidents, one of which occurred at Corus’s Llanwern works in 2000.
The HSE also gave evidence that Corus was aware of serious concerns over the furnace’s safety long before the incident.
In 1994, a water cooler failure had caused a breakout of molten metal and gas. An internal report on the furnace’s condition identified the cooling systems as "safety critical" and recommended improvements to the power plant and water pumps.
The report also recommended a plan for potential plant failures to be drawn up. Corus admitted it had failed to carry out these recommendations.
Several subsequent cooler failures occurred and in 1998 another furnace breakout occurred. Further recommendations for improvements made by an internal committee were also not taken forward. Work to extend the furnace’s life by fitting extra coolers was done in a "haphazard fashion", making leak detection more difficult.
The HSE concluded that the events leading to the explosion were part of a "continued and deteriorating pattern of failures". It plans to publish a report on the incident later this year.
In a statement, Corus said: "We profoundly regret the tragic loss of life and grievous injuries caused by the unprecedented explosion at Port Talbot." The company said it has taken measures to ensure such an incident never happens again.