September 17, 2008
The Honorable James A. Rispoli
Assistant Secretary for Environmental Management
U.S. Department of Energy
1000 Independence Avenue, SW
Washington, DC 20585-0113
Dear Mr. Rispoli:
The Defense Nuclear Facilities Safety Board (Board) remains focused on the safety or aging electrical systems in nuclear Facilities at the Hanford Site. As part of this focus, members of the Board's staff visited the Hanford Site recently to review electrical systems at the high level waste (HLW) Tank Farms and the Plutonium Finishing Plant (PFP). Enclosed is a report containing observations made by the staff-observations which include deficiencies that could compromise safety if not corrected.
The main issue at the Tank Farm is the existence of several deficient design conditions affecting electrica1 systems. Examples of these design deficiencies include non-compliance with national codes, improper modifications and settings of circuit breakers, and improper fuses. Some of these deficiencies were identified by electrical calculations and studies conducted years ago, but the deficiencies remain uncorrected.
The Board notes that power to the safety-significant ventilation system for double-shell tanks in the Tank Farms are not classified as safety-significant. This situation is acceptable as long as the time to reach flammable conditions in the tank head space is on the order of a month or longer. However, waste retrieval and transfer operations can reduce this time. If the time to reach flammable conditions are significantly reduced by these operations, the Department of Energy (DOE) should reevaluate the functional classification of the electrical power supply and distribution systems.
The Board's staff also reexamined electrical safety at PFP. The main safely concerns at PFP, identified during a walk down of the electrical systems, are (1) safety-related cables may have exceeded their design life, (2) the potential for short-circuiting safety significant switchgear, and (3) a potential explosion from hydrogen produced by lead-acid batteries.
The Board believes that the identified safety-related deficiencies in electrical systems at PFP should be resolved in order to ensure reliable operation. Regarding deficient design conditions at the Tank Farms, the Board believes DOE should complete an evaluation of deficient design conditions as soon as possible. For those deficiencies posing electrical safety risks, DOE should implement corrective actions on a priority basis. Pursuant to 42 U.S.C. § 2286b (d), the Board requests that DOE brief the Board within 90 days of receipt of this letter on the status of efforts to correct the deficiencies in electrical safety at PFP and the Tank Farms at Hanford.
Ms. Shirley J. Olinger
Mr. David A. Brockman
Mr. Mark B. Whitaker Jr.