Headquarters Daily Report
MARCH 28, 2001
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REPORT NEGATIVE NO INPUT
ATTACHED INPUT RECEIVED RECEIVED
HEADQUARTERS X
REGION I X
REGION II X
REGION III X
REGION IV X
PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION II MARCH 28, 2001
Licensee/Facility: Notification:
Virginia Power Co. MR Number: 2-01-0004
North Anna 1 2 Date: 03/28/01
Richmond,Virginia
Dockets: 50-338,50-339
PWR/W-3-LP,PWR/W-3-LP
Subject: NORTH ANNA POWER STATION FUEL ASSEMBLY TOP NOZZLE SEPARATION
Discussion:
On March 24, 2001, a top nozzle separated from a fuel assembly after
having been lowered about six inches into its designated location in the
spent fuel pool. The overall length of the assembly is approximately
twelve feet. The assembly was being returned from a video inspection
point inside the spent fuel pool when the failure occurred. The assembly
fell approximately eleven and one half feet into its designated spent
fuel rack location following the top nozzle separation from the assembly.
Attached to the separated top nozzle was a burnable poison rod assembly.
The licensee found separation at the bulge joint where the top nozzle
thimble sleeve connects to the guide thimble tube via rolled connections.
There are twenty four of these connections that support the weight of the
assembly during movement. A root cause evaluation team has been convened
to determine the failure mechanism. Fuel movement activities have been
temporarily suspended by the licensee during the root cause
investigation.
The failed assembly was of the Westinghouse LOPAR 17 x 17 fuel design. It
was one of the spent fuel assemblies being inspected for eventual
movement to the licensee's dry cask storage area. This fuel assembly had
been burned twice within the core and was placed in the spent fuel pool
sometime in 1984.
Area radiation monitors remained normal during the incident. Area and
airborne surveys by health physics personnel subsequent to the incident
showed no increased radiation readings. Follow up evaluations by the
licensee revealed no evidence of damage to the fuel cladding, fuel rack
or the spent fuel pool liner.
Similar incidents have occurred at the La Hague plant (France) and the
Almaraz plant (Spain). The root cause for both of these incidents was
determined to be Intergranular Stress Corrosion Cracking (IGSCC).
Regional Action:
Routine followup by the resident inspectors.
Contact: J. BLAKE (404)562-4607
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