Optimus: a versatile option

NAC INTERNATIONAL UNVEILED ITS NEW Optimus transport packaging at the 2020 Waste Management conference in Phoenix, Arizona in March. Enhanced capabilities were built into its design following consultation with customers, and so were improvements derived from lessons learned by NAC over many years of on-site, field and over-the-road activity.

Once licensed, it will provide a tailored system for handling and transporting nuclear materials and waste. An array of Optimus designs will offer a wide range of modular shielding options for fissile materials, transuranics (TRU), high activity intermediate-level waste and low-enriched uranium fuel.

We believe Optimus is a versatile, low-cost nuclear waste and material transport solution for commercial and government customers, which is required in an environment where the nuclear industry faces constant pressure to reduce costs while dealing with an expanding nuclear waste assortment.

The nuclear industry is expected to decommission dozens of facilities and reactors over the next decade. Optimus offers options to help dispose of varied classes of waste.

This accelerated decommissioning trend is already well under way in Europe and Asia. In North America, the USA has shuttered several plants, some prematurely, and will ramp up reactor decommissioning in 2030 as plants reach the end of their licences and operating lives.

The US Government, at DOE’s former nuclear weapons sites, has conducted significant decommissioning, but much of the waste due for final off-site disposal still remains on site. Modernisation of the US nuclear weapons and capabilities in national laboratories will also require additional nuclear waste management and ultimately transportation for disposition.

The Optimus premise is that a versatile fleet of smaller packages offers better value, operability and lower risks compared to larger capacity cask systems.

It has two flexible packaging designs accommodating most types of customer waste or material requirements:

• Optimus-H for high-activity contents — remotelynhandled-TRU, spent fuel debris, and other intermediate and high-level wastes.
• Optimus-L for low-activity contents — contact handled-TRU, intermediate-level waste, low-enriched fuel wastes and other contents typically shipped as Type A(F) or Type B.

Size and operations

Both Optimus-L and Optimus-H are smaller and lighter than other transportation cask systems. This allows for packaging with single drum payloads, while providing maximum operational flexibility, particularly for facilities with limited building access openings, lower crane hook heights, and capacities less than 20 tons. Operationally, workers can tie the package directly to a trailer or to NAC’s custom- designed pallet for sites preferring or requiring forklift handling operations.

With fewer, simpler steps, a smaller crew can perform loading or unloading operations, which require around one person-hour for each package.

With smaller packaging test volumes and less mass allowing for temperature stabilization, less time is required to perform pre-shipment pressure decay leak-rate testing on each package. The smaller packaging size and lower bolt torque requirements also mean a single person can perform the bolting operation, without the time and cost of installing or using person-lifts.

Shipping campaigns

During shipping, a standard 18-wheeler truck trailer can accommodate up to eight Optimus-L packages for low-dose drum shipments. For high-dose drums, a combination of Optimus-H or Optimus-L packages will accommodate three to four payloads on one trailer.

The Optimus packaging is small, lightweight, and divisible. The design allows the number of packages per shipment to be reduced to four or five Optimus-L packages per trailer. For year-round shipments, one Optimus-H package plus one Optimus-L package can be deployed per trailer during months where the roadway ‘frost laws’ are in effect. It is a legal weight transport, so it does not require dedicated trailers or special road transport permitting.

NAC submitted certification documents for Optimus-H to the Canadian Nuclear Safety Commission (CNSC) in July 2018 and is expecting a Certificate of Compliance (CoC) in 2020.

Enhanced operational flexibility

Compared to large casks under similar scenarios, Optimus offers significant flexibility to address project unknowns, whereas a large cask could become a stranded, expensive asset.

Enables higher source term payloads

The Optimus system accommodates higher fissile material loadings, higher dose contents, and higher concentration of compacted waste and gas generating contents per drum than any standard large road packages. Shield inserts up to 3.25 inches can be added to substantially increase activity limits for specific contents.

Reliable fabrication and transport fleet

The first Optimus packaging was fabricated recently in New Jersey, USA and fabrication activities continue. It is under regulatory review and approval has been sought.

NAC submitted certification documents for Optimus-H to the Canadian Nuclear Safety Commission (CNSC), in July 2018 and is expecting to receive a Certificate of Compliance (CoC) this year.

The application for Optimus-L was submitted to the CNSC in 2019, and we also expect to receive the certificate in 2020. Since the main components (ie, containment vessel and closure system) of the Optmus-L are identical to the Optimus-H, we do not expect any major challenges in obtaining Canadian regulatory approval.

NAC plans to apply to the US Nuclear Regulatory Commission for certification later this year. It also plans to obtain international certifications in the future as the market expands.

Author information: Juan Subiry is Vice president of market and product strategy at NAC International