05000244/LER-2004-002

LER-2004-002, Consolidated Rod Storage Canister Placed in Incorrect Storage Location

Docket Number
Event date:
Report date:
2442004002R00 - NRC Website

I. PRE-EVENT PLANT CONDITIONS:

On December 13, 2004, R.E. Ginna Nuclear Power Plant (Ginna) was in Mode 1 at approximately 100% steady state reactor power.

II. DESCRIPTION OF EVENT:

A. EVENT (INCLUDING DATES AND APPROXIMATE TIMES OF OCCURRENCES):

In October of 1972, the last of the initial fuel assemblies, which would subsequently be placed in consolidated rod storage canisters, were off-loaded and stored in the spent fuel pool. All original A-series, B-series, and C-series fuel assemblies were subsequently sent to the West Valley Demonstration Project (WVDP) for reprocessing. .....

In 1985-1987, assemblies A01-A41 and B01-B40 were returned to Ginna from the WVDP.

Eleven of the A-series assemblies (A02, A03, A05, A20, A21, A22, A23, A24, A39, A40, and A41) were consolidated into eight consolidated rod storage canisters as part of a demonstration project before being returned to Ginna. Information associated with the assemblies and canisters was added to the site Nuclear Fuel Accounting Code (NFAC) computer database. This information included adding the quantities of the various special nuclear material isotopes, the burnup of each assembly (in MWD), and the initial mass of Uranium (kgU). It appears that an error may have been made in the total energy generated by the fuel rods in canisters CO2, C07, and IC4 . This was not determined previously since the isotope quantities for special nuclear material (SNM) accountability were determined from the material transfer reports.

In May of 2000, Ginna submitted a license amendment request for the use of soluble boron credit in the spent fuel pool to address Boraflex degradation issues.

In December of 2000, Amendment 79 to Ginna operating license was received from the NRC allowing for soluble boron credit in the spent fuel pool. This amendment requires fuel assemblies be classified according to their initial enrichment and burnup, and only allows specific combinations of face adjacent assemblies to provide high confidence of subcriticality under worst case conditions.

• In February of 2001, a large number of fuel assembly moves were carried out to be in compliance with Amendment 79. Assemblies were categorized based on initial enrichment and burnup from NFAC. NFAC contains canister data but not data for individual assemblies contained in the canisters. The assembly moves were planned by one individual and verified to be acceptable by another individual. At that time, canister IC4 and assemblies F44 and Z26 were placed in what were believed to be acceptable storage locations within the spent fuel pool.

In June of 2004, the reactor engineer began pulling old fuel-related data together with the goal of preparing a single-source design analysis document with the Ginna fuel history, revalidating the data in the process. Information on the number of rods from each assembly in each canister was determined at that time.

On December 10, 2004, the reactor engineer began working on a letter to the refueling contractor detailing the proposed offload plan for the 2005 refueling outage. The plan required the removal of consolidated canister CO3 from Region 1 (borated stainless steel flux-trap type racks) to open up cells for the 2005 refueling outage offload. Canister CO3 was classified as "A2" based on contained assemblies. While looking for a suitable location in Region 2 Type 1 racks, it was noted that three consolidated rod storage canisters were classified as "Al".� On December 13, 2004 at 0900 EST, following a review of information collected for the database effort, it was determined that canisters CO2, C07, and IC4 were misclassified based on the contained assemblies. It was also determined that cannister IC4 was stored in violation of Improved Technical Specification (ITS) section 4.3.1.1(d) and LCO 3.7.13, due to face adjacent category "B" assemblies (F44 and Z26). Actions were immediately initiated to return the storage of the fuel to an acceptable configuration.

B. INOPERABLE STRUCTURES, COMPONENTS, OR SYSTEMS THAT CONTRIBUTED TO

THE EVENT:� .

None

C. OTHER SYSTEMS OR SECONDARY FUNCTIONS AFFECTED:

None

D. METHOD OF DISCOVERY:

This condition was discovered by the reactor engineer during administrative preparations for the 2005 refueling outage. Subsequently, the reactor engineer notified higher supervision.

E. SAFETY SYSTEM RESPONSES:� , None.

.�.

III. CAUSE OF EVENT:

The immediate cause of being in a condition prohibited by Technical Specifications was not fully meeting the requirements of ITS section 4.3.1.1(d) and LCO 3.7.13, since consolidated rod storage canister IC4 was located face adjacent to two higher category "B" fuel assemblies .

The underlying cause of consolidated rod storage canister IC4 being in an unacceptable storage location was an error in the input of information into the NFAC computer database, which led to the mis- categorization of the consolidated rod storage canister.

This event is NUREG-1022 Cause Code (A), "Personnel Error".

IV. ASSESSMENT OF THE SAFETY CONSEQUENCES OF THE EVENT:

This event is reportable in accordance with 10 CFR 50.73, Licensee Event Report System, item (a) (2) (i) (B), which requires a report of, "Any operation or condition prohibited by the plant's Technical Specifications". Storage of a consolidated rod storage cannister classified as "A2" face adjacent to category "B" assemblies is prohibited by the Improved Technical Specifications.

An assessment was performed considering both the safety consequences and implications of this event with the following results and conclusions:

i There were no operational or safety consequences or implications attributed to having the consolidated rod storage cannister IC4 face adjacent to category "B" assemblies because:

The analysis justifying the categorization scheme for spent fuel assemblies (Final Report, R.E.

Ginna Nuclear Power Plant Criticality Safety Analysis for the Spent Fuel Pool Storage Rack Using Soluble Boron Credit, February 2000; attached to Amendment 79 submittal) was reviewed. It was determined that consolidated rod storage canisters were treated very conservatively within the analysis by bounding them (categorization) by the most reactive assembly they contain. Consolidated rod storage canister IC4 contains 276 rods from two assemblies. It is actually less reactive due to its internal configuration than a Westinghouse standard fuel assembly with 45,000 MWD/MTU burnup, which would be classified as an "Al" assembly. The consolidated rod storage canisters are conservatively categorized to provide for ease of implementation of Technical Specification requirements.

Based on the above, it can be concluded that the public's health and safety was assured at all times.

V.�CORRECTIVE ACTIONS:

A. ACTION TAKEN TO RETURN AFFECTED SYSTEMS TO PRE-EVENT NORMAL

STATUS:

The face adjacent category "B" assemblies (F44 and Z26) were moved to an acceptable storage location within the spent fuel pool.

B. ACTION TAKEN OR PLANNED TO PREVENT RECURRENCE:

The procedure utilized for fuel and core component movement has been revised with a note stating that all consolidated fuel canisters are classified as "A2" based on the contained fuel assemblies and that the categorization will not change (i.e. go to a lower reactivity category) in the future since the contained assemblies have decayed for greater than the longest interval in the technical specification curves (20 yrs). This effectively removes the possibility of another error that caused the mis-classification of this type.

VI.�ADDITIONAL INFORMATION:

A. FAILED COMPONENTS:

None

B. PREVIOUS LERs ON SIMILAR EVENTS:

A similar LER event historical search was conducted with the following results: No documentation of similar LER events with the same root cause at Ginna Station could be identified.