05000301/LER-2006-002

LER-2006-002,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3012006002R00 - NRC Website

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)

Event Description:

On June 26, 2006, Point Beach Nuclear Plant (PBNP) discovered that 12 fuel assemblies stored in the spent fuel pool [DA] do not meet the requirements of Technical Specification 3.7.12.

Technical Specification 3.7.12 requires fuel assemblies with an initial enrichment greater than 4.60 weight percent to have an acceptable number of Integral Fuel Burnable Absorber (IFBA) rods based on Figure 3.7.12-1. The 12 assemblies in question had a nominal initial enrichment of 4.70 weight percent and no IFBA rods. Per Figure 3.7.12-1, fuel with an initial enrichment of 4.70 weight percent requires at least four 1.0X IFBA rods.

Different criticality analysis and Technical Specification requirements were in place when the fuel assemblies were purchased and put into use. When the assemblies were purchased, the approved criticality analysis upper limit on initial enrichment was 4.75 weight percent and IFBA was not required.

A license amendment to use a new criticality analysis was approved by the Commission on September 4, 1997, which is the present analysis of record. The new criticality analysis allows fuel with enrichment up to 5.00 weight percent, but requires that fuel with an initial enrichment greater than 4.60 weight percent have a certain number of IFBA rods (based on initial enrichment) to ensure the requirements for SFP keffective (keff) are met. At the time, these 12 assemblies were recognized as not meeting the new requirements. To accommodate these assemblies, an alternate analysis methodology was included in the Technical Specifications. It stated that if assemblies with initial enrichment greater than 4.60 weight percent can be demonstrated to have a kinfinite (kinf) less than a specified value, they would also be acceptable for storage.

When PBNP received the new criticality analysis, a separate report was also received that demonstrated that the kinf for the 12 assemblies was below the Westinghouse specified value and the assemblies were acceptable for storage. At that time, PBNP was in full compliance with the Technical Specification requirements for fuel storage.

On February 26, 1999, Westinghouse issued NSAL-99-003. The advisory letter stated Westinghouse was abandoning the kinf methodology because it could lead to IFBA requirements which are lower than those required by the IFBA enrichment curve. Westinghouse requested that plants with both the kinf and IFBA enrichment curve methodologies to use only the IFBA enrichment curve.

PBNP submitted License Amendment Request (LAR) 214 to remove the kinf methodology from the Technical Specifications without recognizing that it would affect these 12 assemblies. This condition has existed since March 20, 2000, when the amendment to remove the kinf methodology was approved by the Commission.

On June 26, 2006, at 1440, the plant entered Technical Specification Action Condition (TSAC) 3.7.12.A.1, which requires the spent fuel pool to be restored within fuel storage limits immediately. This condition remains in effect pending LAR approval.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) POINT BEACH NUCLEAR PLANT UNIT 2 05000301 YEAR Component and system Description:

The spent fuel pool will accommodate 1502 fuel assemblies. The new and spent fuel storage racks are designed so it is not possible to insert assemblies in other than the prescribed locations. In addition, the spent fuel pool has an area set aside for accepting spent fuel shipping casks or dry storage casks.

Borated water is used to fill the spent fuel storage pool at a concentration to match or exceed that used in the reactor cavity and refueling canal during refueling operations. The fuel in the spent fuel pool is stored vertically in an array with sufficient center-to-center distance and intervening solid neutron absorber between assemblies to assure keff assemblies.

Event Analysis and Safety Significance:

Each of the 12 fuel assemblies has a burnup greater than 45,000 MWD/MTU. Therefore, the current enrichment of the fuel is far below the initial enrichment. Storage of the 12 assemblies had previously been evaluated as being acceptable for storage in the SFP in accordance with an approved methodology.

Although the PBNP license was amended to no longer rely on that methodology, the physical factors for assuring safety of the assemblies' storage in the SFP did not change. A new criticality analysis confirms the adequacy of the previous assessment by demonstrating that these assemblies may be used in any configuration in the SFP, even if it is filled with unborated water and no Boraflex is present. Therefore, this condition is of low safety significance.

Cause:

The apparent cause of this event was failure to validate and verify that there were assemblies that could be affected when the Technical Specification change was made to remove the kinf methodology.

Corrective Action:

A license amendment to correct this condition is under development. The amendment is based on a new analysis that takes credit for the burnup of the fuel assemblies. Under the new proposed criticality analysis, the 12 assemblies are acceptable for storage.

A new administrative procedure was issued on June 28, 2006. This procedure includes a "Reload Safety Licensing Checklist" as part of the design process and ensures that new fuel will meet Technical Specification requirements.

FACILITY NAME (1) DOCKET NUMBER i2) LER NUMBER (6) PAGE (3) POINT BEACH NUCLEAR PLANT UNIT 2 05000301

Previous Similar Events:

LER Number� Title 266/1975-018-00� Three Fuel Assemblies Determined to be in Wrong Position in the Spent Fuel Pool.