SAN FRANCISCO - Pacific Gas and Electric Company today announced that it has identified and is working to resolve conflicting documentation about the storage location of a small amount of used nuclear fuel at its Humboldt Bay Power Plant, near Eureka in Northern California. The issue relates to records of the movement of used nuclear fuel more than 34 years ago, and has no impact on the health and safety of the public. The amount of fuel in question consists of three, half-inch diameter by 18-inch long segments, weighing a total of about 4 pounds, which were cut from a single, seven-foot fuel rod in 1968.

Plant records indicate that these segments may have been shipped offsite in 1969, as part of a larger shipment of used fuel sent for reprocessing. However, recently reviewed documents indicate the fuel may have remained stored safely underwater since 1968, in the plant's used fuel pool, where other used nuclear fuel is stored. Plant employees are now in the process of retrieving and examining additional records, as well as meticulously searching the contents of the used fuel pool, to determine which document is accurate.

"The fuel rod segments remain in the used fuel pool, or were shipped offsite to an appropriate, controlled facility - either for analysis or reprocessing," said Greg Rueger, senior vice president for generation and Chief Nuclear Officer for the utility. "However, we must ensure we have accurate records, and that entails a meticulous search of the pool itself, to confirm the location of these three used fuel segments."

In the late 1960's up to the mid-1970's, nuclear power plants were permitted to ship used nuclear fuel offsite for reprocessing to be used again. The fuel in question would have gone to the Nuclear Fuel Services reprocessing facility, located in West Valley, New York. The Humboldt power plant, which opened in 1963, ceased operations in 1976. No fuel has been shipped offsite since 1974.

The security in place at the Humboldt plant now and throughout its existence adds to the strong belief that the fuel was either appropriately shipped offsite, or stored in the pool. There is no way these used fuel segments could have been removed inappropriately from the site without detection by an extensive array of radiation monitors. Further, to be handled safely, the segments would have to be encased in a steel-and-lead container weighing nearly one ton, and could only have been moved with special handling equipment designed for this purpose.

Conflicting Records

Since late 2003, PG&E plant personnel have been in the process of conducting a meticulous search of the plant's records, and verifying and characterizing the contents of the used fuel pool, in preparation for the upcoming decommissioning of the plant and movement of the used fuel pool contents to dry cask storage. On June 23, 2004, while undertaking this review, PG&E personnel discovered the first indication of a discrepancy in documentation, as they reviewed minutes of the plant's On-Site Review Committee (OSRC) meetings from 1968. Those minutes revealed one fuel rod had been removed from a fuel assembly and three approximately 18-inch-long segments were cut from it. (Fuel rods, which are about seven feet long, are typically secured in what is called a fuel assembly, which in this case consists of 49 fuel rods.) These three segments were to be shipped offsite for analysis at the Battelle Laboratory in Columbus, Ohio in September 1968. However, these OSRC minutes further indicate the shipment was cancelled and the three fuel segments, along with the remnants of the cut fuel rod, did not leave the Humboldt plant and were returned to the used fuel pool. The documents note that the remnants of the cut rod were deposited in the pool's main (central) storage container (used to store miscellaneous irradiated components), but the exact location in the pool of the three segments was not identified.

These 1968 OSRC minutes conflict with the plant's current used fuel inventory, which does not identify this fuel rod as being located at the plant. In fact, documentation was reviewed on June 25, 2004, which indicates that the entire fuel assembly was shipped offsite for reprocessing at the West Valley facility on August 6, 1969. This shipping record does not indicate that one fuel rod had been removed from the assembly. It is now considered likely that this record is not complete, and the fuel assembly was shipped in 1969 without the fuel rod in question.

Further review of records did not resolve this discrepancy, so on June 28, PG&E verbally notified the Nuclear Regulatory Commission (NRC) Region IV office of the matter.

Investigation Status

Plant personnel have continued to review records, and on July 7, began a physical search of the used fuel pool focused on locating the segmented fuel rod in question. The pool, which is from 26 to 30 feet deep and 22 feet wide by 28 feet long, must be searched slowly and methodically, using underwater cameras and remote-controlled tools on long poles. There are 390 used fuel assemblies stored in the pool, with numerous spaces between and around them. In addition, there are six storage containers filled with various irradiated hardware and components. Each of these storage containers must be emptied piece-by-piece to conduct a full search for the fuel segments. They are 8 feet long and range in dimension from four to about nine inches square. Two of these containers, including the main storage container, have been searched and their contents inventoried.

On July 9-11, 2004, this search appears to have verified that the remnants of the cut fuel rod in question are located in the main storage container, as indicated in the OSRC minutes. In an effort to verify that the three 18-inch segments are also in the pool, the physical search is continuing.

"It may take several more weeks to finish an exhaustive review of the appropriate docu­ments from the 1960's and conduct a full search of the pool, but we are putting significant effort into resolving this discrepancy as quickly as possible. We want there to be no question about how seriously we take our responsibility to safely store used fuel," Rueger said.

Next Steps

PG&E has continuously updated the NRC on the status of the investigation, and regional NRC personnel have inspected the site and are monitoring progress.

PG&E is continuing its documentation search, and has begun interviewing current and former plant personnel who worked at the plant as far back as 1967. The utility is requesting Nuclear Fuel Services, Inc. and the Battelle Laboratory provide access to their records, for this review.

The investigation could take several more weeks to complete, largely because of the difficulty associated with physically searching the used fuel pool.