Kenneth Fletcher
WC Monitor
3/28/2014
Contractors at the Savannah River Site are undertaking corrective actions after a damaging freeze shut down the site’s steam lines, and a review released this week showed poor communication following the event and an over-dependence on steam at facilities. The Jan. 7 freeze shut down the site’s biomass plant and associated steam lines, which in turn shut down facilities across the site. “The over reliance on steam availability by the DOE-SR line organizations delayed actions for securing systems until the event reached a critical stage,” states an evaluation of the event performed by the DOE Savannah River Operations Office. “The back-up boiler was in place to operate in the event of a loss of the main boilers, but it also failed to operate due to freezing of critical components. The communications from SUD [Site Utility Department] to the line organizations was less than adequate and did not convey the urgency of the situation.”
Assumed Biomass Would Be As Reliable As Coal
While the steam lines were down from Jan. 7 to Jan. 9, all site facilities in the F, H and S areas were brought down to a safe configuration and some suffered damage from the cold temperatures (WC Monitor, Vol. 25 No. 2). Notably, at the Saltstone Facilities, frozen flush water burst a grout piping line, spilling 50 gallons of contaminated water into a buffer area. The steam supply came from Ameresco’s Biomass Cogeneration Facility, which began operations in early 2012. Previously steam was provided by a coal-powered plant. “Line management assumed supplied steam would have the same reliability as the coal-fired powerhouse based on past operating experiences. However, the coal-fired powerhouse had overcapacity and levels of redundancies that were not designed into the biomass plant,” according to the evaluation.
Precautions Not Effective
While Ameresco took precautions to prepare for the cold weather, they were not effective. “The control room received multiple warning indicators and system malfunction alarms due to the cold temperatures and eventually both boilers tripped due to the activation of an interlock causing a safety shutdown,” the review states, noting that the site’s steam supply was shut off shortly afterward. It recommends that Ameresco validate and upgrade its freeze protection system.
But another issue was that other site facilities did not account for a potential total loss of steam. “The primary issue with the loss of steam was it happened with little warning,” the review states. “The line organizations prepared for the cold, but they assumed they would have steam. When steam was lost, the facilities initiated their shutdown of processes/equipment, but due to the extreme cold, systems began freezing before they could be properly drained.”
The Department hopes to have all corrective actions implemented by the beginning of next winter. “DOE-SR management have accepted the findings in this review and have directed DOE-SR Program managers and SRS contractors to develop corrective actions and implement them by November 2014,” DOE-SR spokesman Jim Giusti said in a written response.
