Vermont Yankee Announces Selection of Holtec International’s HI-STORM 100 Cask System

This Holtec Highlight reflects the July 13, 2015 announcement submitted by Martin Cohn, Senior Communications Specialist, Vermont Yankee and published by The Recorder of Greenfield, Mass.

Entergy Vermont Yankee has selected the Holtec HI-STORM 100 dry storage system at the Vermont Yankee Nuclear Power Station (VY) site. The Holtec HI-STORM 100 System is designed to contain up to 68 Boiling Water Reactor (BWR) fuel assemblies and consists of a stainless steel multi-purpose canister (MPC) with a welded baseplate and lid, which is placed inside a coated carbon steel and concrete overpack that is placed on a concrete pad for storage.

Ariel View of Vermont Yankee Nuclear Station
Ariel View of Vermont Yankee Nuclear Station

The NRC has approved a number of different dry storage designs for general use, and in the process, has analyzed hundreds of safety factors. Each system has unique characteristics that are considered for particular applications, depending on the design of the different plants, spent fuel buildings, geographic locations, etc. Entergy selected Holtec through a competitive bid process involving technical and commercial review of various vendors and systems.


Holtec International’s HI-STORM Cask Systems
Holtec International’s HI-STORM Cask Systems

At a recent Vermont Nuclear Decommissioning Citizens Advisory Panel meeting President/CEO Dr. Kris Singh stated that the canister would last 300 years. He based his estimate on the British Stainless Steel Association’s (BSSA) studies on the durability and life expectancy for stainless steels in external environments. BSSA states that it would take 135 years for corrosion to penetrate 1mm of stainless steel. Since the Holtec canister is 12.7 mm thick, it would take approximately 1,714 years (12.7 times 135 years) to penetrate Holtec’s stainless steel. Therefore, using a safety factor of 5, it would take about 342.9 years or rounded to 300 years.

The Holtec system has an outstanding in-service record and has been in use at Entergy Vermont Yankee, as well as several Entergy plants and many plants throughout the United States.

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Written by Amy Grant

Amy Grant is a graphic designer and web developer. She is the founder of the Southwark Historical Society, a volunteer based group that studies the Southwark Historical District located in Philadelphia, Pennsylvania.