NAC International: A Leader in Used Fuel Storage Technologies

USEC’s subsidiary NAC International provides nuclear utilities with essential used fuel management systems such as the NAC-UMS, NAC-MPC and NAC-STC transportation and storage technologies.

NAC has a quarter century of experience in designing, engineering, licensing, fabricating, operating and maintaining used fuel management systems for storage and transport and has obtained more than 100 NRC-approved license applications and amendments on storage and transport system designs.

NAC has developed 10 major NRC-licensed systems, including the first high-capacity, directly loaded dual purpose system for storage and transport of standard nuclear fuel (NAC-STC) and the first multipurpose (storage and transport) canister based system approved by the NRC (NAC-MPC).

In 2008, NAC expects to receive a draft Certificate of Compliance from the U.S. Nuclear Regulatory Commission (NRC) for approval of its new MAGNASTOR™ system, which offers market-leading fuel capacity and operational features.

The MAGNASTOR™ System:

The New Generation in Multipurpose Storage

The future of dry used-fuel storage has arrived.

The Modular, Advanced Generation, Nuclear All-purpose Storage (MAGNASTOR) System is a new generation of dry, multipurpose used fuel storage technology.

Drawing upon lessons learned from designing and licensing three dual/multipurpose technologies and from fabricating, constructing and loading almost 200 multipurpose canister systems (MCS), NAC has developed MAGNASTOR to provide improved capacity, thermal performance, operations and fuel coverage for the growing number of nuclear power plants requiring dry used fuel storage.

Unique Design, Fabrication, and Operations Features

• A developed cell basket design that offers the highest used fuel capacities, high strength, simplified fabrication and heat removal of up to 35.5 kW
• A unique canister closure design that can reduce welding time and personnel dose while providing enhanced drying performance
• A low profile vertical concrete cask design that provides: improved on-site handling and site dose rates; proven, simple construction and operation features; and robustness against beyond-design-basis threats
• A simple, proven transfer system that facilitates transfer without excessive dose or handling
• A new approach to water removal and canister drying that shortens operation times.

The UMS™ System:

NAC’s First Universal Used Fuel Storage and Transport Solution

After the termination of DOE’s Multi-Purpose Canister (MPC) program in 1995, NAC launched a program to design and license a system that could handle virtually all types of fuel used in U.S. and international commercial nuclear power plants.

NAC based the UMS on the licensed NAC-STC basket and transport overpack designs, enabling a rapid system development. Given the familiarity of the evolutionary design, NAC set licensing targets that would allow the UMS to meet utilities' urgent used fuel needs before 2000.

The UMS provides a single system that embodies the low cost of a storage-only system, the transportability of a dual-purpose canister-based system and the canister benefits envisioned in the former DOE MPC program. The UMS was the first system designed to meet the requirements of virtually every U.S. utility.

The UMS has four primary components: the transportable storage canister, the vertical concrete cask storage overpack, the universal transport cask overpack and the transfer cask and auxiliary equipment.

Other Key Features

• A capacity of 24 PWR or 56 BWR fuel assemblies
• A licensed impact limiter design that uses results from comprehensive drop tests on a quarter-scale model of the NAC-STC
• Multiple basket configurations to accommodate a full range of BWR and PWR fuels
• A hands-on transport and operations-based design perspective
• A comprehensive design review by engineers and manufacturers to ensure that system component designs are easily and efficiently fabricated
• An integrated quality assurance program from start to finish.

Fabrication and Delivery

Superior design and technology are only as good as the supplier's ability to fabricate and deliver the system on time. For the UMS, NAC implemented a comprehensive fabrication program that has led to reliable deliveries of more than 160 high-quality systems.