The worker at the centre of the most serious nuclear safety incident of recent years was found guilty yesterday of concealing information from safety regulators. He could now face five years in jail and a $250,000 fine.
|Davis-Besse: remained safe - no thanks
to Andrew Siemaskzo (Image: NRC)
Andrew Siemaszko deliberately neglected his work in inspecting and maintaining the vessel head of the Davis-Besse reactor in the US state of Ohio and lied to cover his tracks. Because of a manageable fault which Siematzko was specifically meant to have found, the reactor pressure vessel head - a major component with an important safety role - suffered very serious corrosion.
Siemaszko was convicted by a federal judge in Toledo, Ohio for concealing information and for making false statements to the Nuclear Regulatory Commission (NRC). He is yet to be sentenced but could face five years in jail and a fine of up to $250,000.
The affair began in 2001 when the NRC noted that some reactor pressure vessel heads had suffered circumferential cracking in the area they were penetrated by control rod drive mechanisms. The NRC had also found that one sign of cracking could be deposits of the boric acid which makes up a small part of coolant water. The regulator sent a letter to all nuclear plant licensees with pressurised water reactors ordering them to check for cracking and report back on the exact status of their reactor pressure vessel heads. The report was to include an inspection schedule and justification for the safe continued operation of the reactor.
At Davis-Besse, responsibility for this fell to Siemaszko who had the role of coolant system engineer for nuclear operator First Energy Nuclear Operating Company (Fenoc). In various plant documents dated before and after the NRC order, Siemaszko falsely wrote that he had cleaned boron accumulations which could have caused corrosion, and that he had inspected the vessel head and found no damage. This information was used to justify operation until February or March 2002, when the unit was scheduled for a refuelling and maintenance outage.
Had Siemaszko conducted the checks properly he would have immediately found tell-tale boron deposits left by leaks from exactly the cracks the NRC had described. In that situation it is likely the NRC would have ordered the plant to be shut down for repair.
When the scheduled outage came around in mid February 2002, an inspection revealed a cavity in the reactor pressure vessel which by that time had grown to the size of a pineapple. In fact, the entire 16.8 centimetre thickness of the alloy vessel head had been consumed, leaving its stainless steel inner cladding as the pressure boundary.
Following an NRC investigation, Siemazsko was banned from working in any NRC-licensed activities for five years, with the added condition that he would have to formally notify the commission before taking up any NRC-licenced work for a further five years. During legal action he had claimed whistleblower status, but an Department of Labor investigation into this was scrapped after Siemazsko admitted lying to Fenoc.
The deception also involved another man who was put on probation for three years for concealing information from the US government, while a private contractor was acquitted.
For licence violations resulting from Siemaszko's misdeeds, Fenoc was fined $5.45 million by the NRC, its largest ever penalty. The company also suffered a two-year shutdown of the unit for expensive repairs, during which it had to buy replacement power.