United States Nuclear Regulatory Commission

Office of Public Affairs

Washington, DC 20555

Phone 301-415-8200 Fax 301-415-2234

Internet:opa@nrc.gov

No. 97-079

FOR IMMEDIATE RELEASE

(Friday, May 16, 1997)

NRC SENDS LETTERS TO SIERRA NUCLEAR, THREE UTILITIES

ON SPENT FUEL STORAGE CASK WELDING PROBLEMS

The Nuclear Regulatory Commission's Office of Nuclear

Material Safety and Safeguards has issued Confirmatory Action

Letters to Sierra Nuclear Corporation, designer of the VSC-24 dry

storage cask for spent nuclear fuel, and three utilities that use

the cask at power plants. The letters confirm that Sierra and

the utilities will take certain actions regarding welding

problems with the casks.

The utilities and plants where the casks are used are

Entergy Operations, Inc., operator of Arkansas Nuclear One near

Russellville, Arkansas; Consumers Power Co., operator of the

Palisades nuclear power plant near South Haven, Michigan; and

Wisconsin Electric Power Company, operator of the Point Beach

nuclear power plant near Manitowoc, Wisconsin.

Sierra Nuclear holds an NRC certificate approving the use of

the VSC-24. NRC conducts inspections to determine whether the

system is being manufactured in accordance with the NRC-certified

design.

An inspection conducted the week of March 17 at Sierra

Nuclear and two of its fabrication contractor facilities focused

on problems previously found in welds joining the inner cask lid

to the cask walls in VSC-24 units at the Palisades and Arkansas

plants. Following that inspection, problems arose while welding

another Arkansas cask.

The March inspection revealed that neither Sierra Nuclear

nor the utility licensees had performed a comprehensive root

cause analysis of the first two weld problems. An understanding

of the root cause is essential to preventing recurrence when

welding future casks, and assessing the possibility of additional

weld problems and cracking.

On May 6, NRC held a public meeting with Sierra Nuclear to

discuss actions taken and planned by the company in response to

the inspection findings. After the meeting, the NRC staff
concluded that the root cause of the weld defects has not been

adequately determined.

The NRC letter to Sierra Nuclear confirms that the company

will determine the root cause of the weld defects, assess the

potential for delayed cracking in welds that attach the two outer

lids to the cask walls in the 19 VSC-24 casks presently in use

(at Arkansas, Palisades and Point Beach), and evaluate

appropriate corrective actions to prevent recurrence of weld

problems. After completing these actions, the company will

submit a written description of these evaluations to the NRC by

June 30.

The NRC letters to the three utilities currently using the

VSC-24 casks confirm that--before loading additional VSC-24 casks

with spent fuel--they will determine that their welding and

inspection practices provide reasonable assurance that cracking,

including possible undetected or delayed cracking, will not occur

in the seal welds between the two outer lids of the cask system

and the cask walls, and, if necessary, modify their welding

processes to inhibit recurrence of the welding problem. After

completing this action, the utilities will submit to the NRC, at

least 14 days before loading another VSC-24 cask with spent fuel,

a written description of any procedural or design modifications

made, including a technical justification for each modification.

Copies of the letters will be available on the NRC Office of

Public Affairs home page at: http://www.nrc.gov/OPA.

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