On October 4, 1993, a security employee at the Savannah River HB-Line facility detected contamination on his shoe cover while performing routine exit monitoring. Health Physics (HP) personnel performed a whole body frisk and confirmed a reading of 20,000 dpm alpha on the shoe cover. The HP technician also detected contamination on her shoe cover (60,000 dpm alpha) and on the shoe cover of an operator entering the Scrap Recovery control room (6,000 dpm alpha). Upon discovery of the contamination, HB-Line personnel requested evacuation of the facility except for a control room watchstander. They then placed the facility on respiratory protection.
HP personnel performed whole body surveys and nasal/saliva smears on all personnel in the radiation control area at the time of the occurrence. Results were negative. They then performed a detailed investigative survey that detected a maximum of 100,000 dpm transferable alpha in one corridor. The radionuclide present was plutonium-238. HP personnel surveyed all floors several hours earlier and detected no contamination. (ORPS Report SR--WSRC-HBLINE-1993-0030)
This event is one in a series of contamination incidents at the facility. On September 15, 1993, two employees discovered 8,000 and 200,000 dpm alpha contamination on their shoe covers while performing routine contamination monitoring. All personnel exited the facility and HP personnel imposed respirator protection requirements. They performed whole body surveys and nasal/saliva smears on the workers in the facility at the time of the occurrence, and results of the smears were negative. Prior to this event on September 14, 1993, HP personnel identified two areas in the control room indicating contamination levels of 2,000 and 4,000 dpm alpha. As a result, they posted the control room as a contamination area. Although the event investigation is still in progress, facility personnel are treating the two events as related incidents. According to the ten-day occurrence report, the source of the contamination was not determined.
The ten-day occurrence report identified the direct cause of these contamination events as poor control and utilization of radiation work permits and the root cause as lack of management oversight and attention. Facility personnel developed corrective actions that included (1) refreshing HB-Line operators on the proper method of self-monitoring, (2) requiring more in-depth routine surveys, (3) changing protective clothing removal procedures for certain areas, and (4) restricting the wearing of the outer pair of coveralls in the control rooms. In addition, HP management assigned a roving inspector to audit the use of radiation work permits and assist in exit monitoring of personnel. Management personnel addressed the root cause of the events by formalizing the "management by walking around" concept where one of four HB-Line Operations managers was required to walk the facility a minimum of four hours a day to emphasize radiological control practices. (ORPS Report SR--WSRC-HBLINE-1993-0027)
A contamination incident at the HB-Line facility on July 25, 1991, resulted in one personnel assimilation and four personnel uptakes. Savannah River personnel define an assimilation as an uptake of radionuclides into the body that results in an annual effective dose equivalent of 0.1 rem. In this event, five workers were contaminated when an operator opened an empty plutonium-238 shipping container. The container was not identified by a radiological control label to indicate that the interior was contaminated. The assimilation resulted in a committed effective dose equivalent of 16 rem. The four other individuals received uptakes resulting in committed effective dose equivalents ranging from 0.035 to 0.9 rem. (ORPS Report SR--WSRC-HBLINE-1991-1013)
These events underscore the importance of comprehensive contamination control practices. These practices include good housekeeping habits, proper personnel monitoring, frequent surveying, thorough decontamination, and strict adherence to radiation work permits. In addition, dedicated management oversight is an integral part of the contamination control process.