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Above: In 2021, APTIM took possession of the SSSB in Virginia and towed it 1,500 nautical miles on a heavy lift barge to Alabama (courtesy of APTIM)

Louisiana-based APTIM, a US company focused on radiological and nuclear facility decommissioning, has completed the dismantlement and disposal of the Surface Ship Support Barge (SSSB) in Mobile, Alabama. APTIM’s experts took nearly 237,400 hours to complete the demolition, working within a specially fabricated structure under strict environmental monitoring. There were no Occupational Safety & Health Administration lost time incidents. APTIM said the contract to dismantle the SSSB was worth $129m.

APTIM Vice President of Business Development Chris Lee said: “This was a first-of-a-kind project completed on behalf of the Navy, which used a unique interagency agreement between Naval Sea Systems Command (NAVSEA) and Nuclear Regulatory Commission (NRC) to facilitate the Navy performing this work in the commercial sector.” He added: “Not only did APTIM complete the work safely and by deadline, but we also brought $28.3m to the economy of Mobile and the surrounding community for labour, tooling, supplies, housing/lodging, and other subcontracted services.”

The SSSB was a radiologically impacted dockside refuelling barge converted from a World War II Navy T2 tanker, originally built by the Alabama Drydock & Shipbuilding Company, now the Alabama Shipyard. The SSSB received, stored, and prepared previously used reactor components designated for ship-out or reuse. It also performed maintenance functions similar to those of a typical pressurised water reactor used fuel pool, except for long-term used fuel storage.

In 2021, APTIM developed, submitted, and received NAVSEA approval following NRC technical review and recommendation to approve a comprehensive Decommissioning Work Plan that provided the roadmap to safely dismantle, size, package, and ship waste material to a licensed disposal site. APTIM took possession of the SSSB in Virginia and towed it 1,500 nautical miles on a heavy lift barge to Alabama where it arrived in June 2021. It was subsequently removed from the water and placed on blocks for dismantlement. The 100-foot-tall 270-foot-long SSSB became part of the waterfront skyline opposite downtown Mobile for several months.

In March, APTIM said it had completed tearing down the “wet pit,” the portion of the vessel where underwater fuel handling and refuelling work had taken place. Shielding on the wet pit included about 2,500 tons of steel-reinforced concrete. Excavators worked to dismantle the vessels heavily shielded wet pit. The work was done inside a tentlike enclosure.

Above: The SSSB wet pit, which once held spent naval nuclear fuel, is demolished (courtesy of APTIM)

Through detailed and complex engineering and planning, the SSSB was systematically dismantled, sized, and packaged for shipment, with more than 8,000 tonnes of waste material sent to a licensed disposal facility outside of Alabama and more than 400 tonnes of ferrous and non-ferrous metals recycled. APTIM said material sizing and packaging took place within an environmentally controlled containment structure to ensure that no radiological emissions occurred outside the structure during demolition, sizing, and packaging activities.

APTIM received approval from NAVSEA based on an NRC technical review and recommendation to release the site. The final report and contract closeout are expected to be completed at the end of October.

Since the beginning of the effort to contract out the work, there has been speculation that the process used to dismantle the SSSB could be a model for the future dismantling of the aircraft carrier USS Enterprise, which was deactivated in 2012 and decommissioned in 2017. Its eight reactors have been defuelled.

In September, the US Department of the Navy released its Record of Decision to select and Commercial Dismantlement for the project. “Under this alternative, the Navy will contract with commercial industry to dismantle ex-Enterprise, including its defuelled reactor plants, and dispose of low-level radiological waste and other hazardous waste at authorised commercial or Department of Energy (DOE) waste disposal facilities,” the Nay said. “This decision will allow the Navy to reduce the Navy inactive ship inventory, eliminate costs associated with maintaining the ship in a safe stowage condition, and dispose of legacy radiological and hazardous wastes in an environmentally responsible manner, while meeting the operational needs of the Navy.”

The Navy selected Commercial Dismantlement “because this alternative safely disposes of the ex-Enterprise, including its hazardous materials, in approximately five years as compared to 15 years or more for other analysed alternatives”. Additionally, this alternative “will have the lowest greenhouse gas emissions, will not require in-water construction work to expand the capacity of the Port of Benton barge slip in Washington state, and will be executed at approximately half the cost to the taxpayer as compared with other alternatives,” the Navy said. “Finally, this alternative supports the Navy mission by allowing the Navy to focus limited public shipyard resources on priority fleet maintenance. This alternative will not result in any decrease in workforce at Puget Sound Naval Shipyard & Intermediate Maintenance Facility. said Mobile was being considered as a potential site for that project along with Brownsville, Texas, and Hampton Roads, Virginia.

Date: Wednesday, 01 November 2023
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