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Nuclear Power Plant Component Transport

Reactor pressure vessels, steam generators, spent nuclear fuel dry storage casks, turbine-generator components, condensers, and large nuclear plant equipment transported nationwide with oversize and overweight permits — R&RM LLC, based in Cumming, Georgia, serving all 48 continental states since 2011.

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Nuclear Power Plant Component Hauling

Nuclear power plants contain some of the heaviest individual components transported on American highways. Reactor pressure vessels, steam generators, pressurizers, and large condensers routinely weigh 200,000 to 800,000 pounds — well into superload territory in every state — and require multi-axle hydraulic platform trailers, months of permit planning, and military-grade route engineering to move safely. R&RM LLC has transported oversize and overweight industrial equipment since 2011, operating out of Cumming, Georgia and covering all 48 continental states. Our experience with oversize load transport and permit acquisition for industrial and utility equipment makes us a capable partner for nuclear component moves ranging from equipment deliveries for new plant construction to replacement component transport at operating plants.

Nuclear component transport is subject to more layers of regulatory oversight than standard heavy haul. In addition to state oversize and overweight permits, transport of nuclear components may be subject to requirements from the Nuclear Regulatory Commission (NRC), the U.S. Department of Transportation's Pipeline and Hazardous Materials Safety Administration (PHMSA) for radioactive material shipments, and the plant owner's own transport control procedures. Non-radioactive nuclear plant components — new replacement steam generators, reactor vessel heads, condensers, and turbine-generator equipment — are governed by standard oversize permit rules, but the shipping specifications issued by the equipment manufacturer and the plant owner's project team add additional requirements for transport vibration limits, tilt restrictions, and environmental exposure controls that must be incorporated into the transport plan.

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Reactor Pressure Vessels and Reactor Vessel Heads

The reactor pressure vessel (RPV) is the primary structural container of the nuclear reactor core. In a pressurized water reactor (PWR) — the most common reactor type in the United States — the RPV is a thick-walled cylindrical steel vessel typically 14 to 16 feet in inner diameter and 40 to 50 feet tall, with a domed bottom head and a removable upper closure head. Fabricated from specially alloyed low-alloy carbon steel with a stainless steel cladding on the interior wetted surfaces, a new RPV for a large light-water reactor weighs 400,000 to 800,000 pounds or more depending on reactor power class.

New RPVs for plants under construction — such as the AP1000 units being built in the United States and internationally — are manufactured in specialized heavy forging and fabrication shops in South Korea, Japan, and the United States. Delivering a new RPV to a construction site involves coordinating the port unloading at a deepwater dock, the heavy haul transport over public highways from the port to the plant site, and the final positioning move at the plant for reactor building installation. Because the vessel occupies the critical path of the reactor building construction schedule, on-time delivery is paramount.

Reactor vessel upper closure heads — the removable upper portion of the RPV that is unbolted and lifted off during refueling outages to allow access to the fuel assemblies — are replaced at some plants due to stress corrosion cracking of the control rod drive mechanism nozzles or after a specified service life. A PWR reactor vessel head weighs 40,000 to 100,000 pounds and is approximately 12 to 16 feet in diameter and 5 to 8 feet tall. Replacement heads are transported from the fabrication shop to the plant site and require careful dimensional control during transport because the head's flange geometry must maintain tight tolerances for the vessel closure seal. Used reactor vessel heads removed from operating plants are lightly radioactive and require low-specific-activity (LSA) radioactive material shipping classification and documentation under PHMSA's 49 CFR Part 173 requirements.

Steam Generators and Pressurizers

Steam generators in pressurized water reactors are large heat exchangers that transfer heat from the primary reactor coolant (which flows through the reactor vessel and must be kept isolated from the secondary system) to a secondary water circuit that produces the steam driving the turbine-generator. A large PWR plant has two to four steam generators. Each steam generator is a vertical cylindrical vessel 60 to 70 feet tall and 12 to 15 feet in outer diameter, weighing 300,000 to 600,000 pounds.

Steam generator replacement is one of the most complex and commercially significant maintenance operations at an operating nuclear plant. As steam generator tubes degrade from stress corrosion cracking over decades of service, a point is reached where replacing the entire steam generator is more economical than continued plugging of degraded tubes. Steam generator replacements at operating U.S. plants have occurred at dozens of sites since the 1990s. The replacement process involves cutting an opening in the reactor building containment, removing the old steam generators, and installing the new generators through the opening — a process that takes a planned refueling outage window of several months.

Transporting the replacement steam generators from the manufacturing facility (historic U.S. sources include Babcock & Wilcox in Virginia and Combustion Engineering in Connecticut; current sources include manufacturers in France, South Korea, and Japan) to the plant requires multi-axle hydraulic platform trailer configurations capable of carrying 300,000 to 600,000 pounds, superload permits in every state traversed, bridge engineering reviews for all structure crossings, and coordination with the plant owner's nuclear safety team. The old steam generators, now classified as large low-level radioactive waste components, must also be transported to a licensed low-level radioactive waste disposal facility or a licensed storage facility — a transport that requires NRC licenses and PHMSA radioactive material shipping documentation.

Pressurizers — the vertical cylindrical vessels that control primary system pressure in PWRs — are smaller than steam generators but still substantial: approximately 7 to 8 feet in outer diameter, 40 to 45 feet tall, and weighing 100,000 to 200,000 pounds. Pressurizers have been replaced at several U.S. plants and require similar superload transport logistics as steam generators.

Spent Nuclear Fuel Dry Storage Casks

Spent nuclear fuel (SNF) discharged from reactor cores is initially stored in the plant's spent fuel pool for several years to allow the fuel's radioactive decay heat and radiation levels to decrease. Once the fuel has cooled sufficiently, it can be loaded into dry storage casks for long-term storage on the plant's independent spent fuel storage installation (ISFSI) pad. Moving loaded spent fuel casks from the fuel building to the ISFSI — and eventually transporting casks off-site to a consolidated interim storage facility or permanent repository — involves some of the most tightly regulated heavy haul transport operations in the United States.

Dry storage casks are massive steel and concrete structures designed to shield the radiation from the spent fuel, provide structural protection in an accident, and maintain the fuel in a dry, inert atmosphere for decades. Vertical concrete casks (VCCs) are the most common design at operating U.S. plants: a concrete overpack approximately 10 to 11 feet in outer diameter and 18 to 20 feet tall, weighing 150,000 to 200,000 pounds when loaded with a canister of spent fuel. Metal casks, such as the NUHOMS horizontal storage modules and TN-68 and HI-STORM designs, use different configurations but similar weight ranges.

On-site cask movements from the transfer facility to the ISFSI pad are performed with specialized hydraulic self-propelled modular transporters (SPMTs) or purpose-built cask transporters rather than over-the-road trailers. Off-site transport of loaded spent fuel casks to a licensed storage facility requires NRC-certified transport cask configurations (truck casks or rail casks), PHMSA Type B radioactive material shipping documentation, and an NRC-approved shipment route. R&RM LLC's experience with heavy pressure vessel transport and multi-axle trailer operations is directly applicable to on-site cask movement support and the transport of unloaded or empty storage casks and ancillary ISFSI equipment.

Turbine-Generators and Main Transformers

The turbine-generator building at a nuclear power plant contains one of the largest individual pieces of rotating machinery in industrial use. A nuclear steam turbine-generator for a large 1,000 MWe to 1,600 MWe plant consists of a high-pressure turbine section, two to three low-pressure turbine sections (each in a separate casing), and an air-cooled or hydrogen-cooled generator — a combined train that may be 200 to 300 feet long and weigh 3,000 to 6,000 tons as an installed system.

Individual major components are shipped separately from the turbine manufacturer: LP (low-pressure) turbine casings, inner cylinders, rotor forgings, and the generator stator are among the heaviest individual transport items. A large LP turbine casing half-shell may weigh 100,000 to 300,000 pounds and measure 30 to 40 feet long and 20 to 25 feet wide. The generator stator — the stationary winding structure surrounding the spinning rotor — is typically 25 to 35 feet long, 12 to 16 feet in diameter, and weighs 200,000 to 500,000 pounds. These components are among the heaviest items regularly transported on U.S. highways outside of the utility transformer and RPV categories.

The main power transformer associated with a nuclear plant — the generator step-up transformer (GSU) that steps the generator output voltage up to transmission voltage for connection to the grid — is one of the heaviest road-transportable components at a nuclear site. Large nuclear plant GSUs operate at 500 kV to 765 kV and weigh 300,000 to 700,000 pounds. See our power transformer transport page for complete details on transformer hauling logistics. R&RM LLC has transported large utility transformers and industrial equipment of comparable weight for utility and industrial customers across all 48 states.

Condensers and Large Heat Exchangers

The main condenser at a nuclear power plant condenses the exhaust steam from the low-pressure turbines back to liquid water for return to the steam generator (in a PWR) or the reactor vessel (in a boiling water reactor). Main condensers for large nuclear plants are massive shell-and-tube heat exchangers: a complete condenser assembly with two or three shells may be 60 to 100 feet long, 15 to 25 feet wide, and 15 to 20 feet tall, weighing 200,000 to 500,000 pounds as a shipped assembly or significantly more for the complete installed unit.

Condensers are typically manufactured in sections and shipped as separate transport loads that are field-assembled inside the turbine building. Individual condenser shell sections for a large nuclear plant may weigh 50,000 to 150,000 pounds each, requiring multi-axle lowboy or RGN transport with overweight permits. Condenser tube replacement — a maintenance operation that involves removing and replacing the condenser tubes to restore heat transfer performance — generates transport moves for the tube bundle assemblies and the old tube material being removed from the plant.

Other large heat exchangers at nuclear plants include the residual heat removal (RHR) heat exchangers, component cooling water (CCW) heat exchangers, and reactor coolant pump (RCP) motor coolers. These items are smaller than the main condenser but still substantial — RHR heat exchangers for a large PWR may weigh 20,000 to 60,000 pounds each. Plant life extension projects that replace aging heat exchangers generate transport demand for both the new equipment deliveries and the removal of the old equipment.

Nuclear Plant Construction Equipment and Heavy Lifts

New nuclear plant construction projects — including the AP1000 units at Plant Vogtle in Georgia and advanced reactor designs now in licensing and early construction — require the same construction equipment as other large industrial construction projects, but at greater scale and with stricter quality documentation requirements. Crawling and lattice boom cranes capable of lifts of 1,000 to 3,000 tons are required for major nuclear plant lifts, and transporting these cranes to the construction site involves multi-axle heavy haul moves for the crane components. Crawler crane base sections, carbody structures, and transport frames for major lift cranes weigh 80,000 to 300,000 pounds per component. See our crane transport page for details on moving large crawler and lattice boom cranes.

Trailer Selection for Nuclear Plant Components

The heaviest nuclear plant components require trailer configurations that are rarely used outside of nuclear, utility, and large petrochemical transport. Selecting the right trailer configuration requires knowing the component's weight, center of gravity, permitted footprint dimensions, and the structural limitations of the trailer interface points.

Multi-Axle Lowboy Trailers

For nuclear components in the 100,000 to 400,000 pound range that can be loaded at or near ground level — condenser sections, steam generator components, reactor vessel heads — multi-axle lowboy trailers with 10 to 20 axle lines provide the weight distribution needed to keep per-axle loads within state permit limits. A 20-axle lowboy configuration in a B-train (power unit pulling a fixed gooseneck lowboy connected to a trailing booster) arrangement is a common configuration for 300,000 to 400,000 pound nuclear components.

Hydraulic Platform Trailers

Self-propelled modular transporters (SPMTs) and conventional hydraulic platform trailers from manufacturers such as Goldhofer, Scheuerle, and Nicolas are the workhorses of extremely heavy nuclear component transport. SPMTs allow the trailer footprint to be configured around the component's support points, distribute the load across any number of axle lines, and maneuver in tight plant site conditions that exceed the turning capabilities of conventional trailer configurations. A 400,000 to 700,000 pound nuclear component typically moves on a 24- to 40-axle hydraulic platform trailer configuration.

Specialized Cask Transporters

On-site transport of loaded spent fuel casks uses purpose-built cask transporter vehicles designed to the nuclear plant's specific cask model and transfer route requirements. These transporters are not highway-legal and operate only within the licensed plant boundary. R&RM LLC focuses on the over-the-road highway transport portions of nuclear component moves rather than on-site cask transfer operations.

Oversize & Overweight Permit Requirements

Nuclear plant component moves are among the most complex oversize permit projects in highway transport. R&RM LLC manages all permit applications through established relationships with permit agents experienced in each state's requirements:

For detailed information on how superload permits work, see our superload permits guide. For multi-state moves, our multi-state permit coordination guide explains the process of managing permits across multiple state agencies.

Industries and Customers We Serve

R&RM LLC transports nuclear plant components for a range of nuclear industry customers:

What to Provide for a Quote

Complete and accurate information allows R&RM LLC to select the correct trailer configuration, evaluate permit requirements, and provide an accurate quote for nuclear plant component transport:

Call (404) 987-6225 or submit the online quote form with this information. R&RM LLC — based in Cumming, Georgia and in business since 2011 — handles oversize load transport and overweight load transport for nuclear plant equipment and other industrial components across all 48 continental states.

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Nuclear Plant Component Transport Specialists

Reactor vessels, steam generators, spent fuel casks, and turbine-generators — superload permits and specialized trailers across all 48 states since 2011.

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