Lead Shielding Attached to Safety Related Systems Without 10 CFR 50.59 Evaluations
See IE Information Notice No. 83-64 entitled as above and dated September 29, 1983.
This document informs licensees that failure to analyze for possible seismic and structural effects, both dynamic and static, from lead shielding on safety-related systems constitutes an unreviewed safety question. In addition to this document, see IE Circular No. 80-18, "10 CFR 50.59 Safety Evaluation for Changes to Radioactive Waste Treatment System" (see HPPOS-086).
During a routine inspection, an NRC inspector noted that portions of safety-related piping in the primary auxiliary building of a power station was covered with lead shielding. Discussions with the plant engineering staff revealed that licensee safety evaluations supporting this modification had not been done.
The licensee had neither formal control mechanisms to govern the installation, use, and accounting of the temporary shielding, nor records to document the dates and locations of the shielding installations. The shielding was placed on plant systems during a period when high fuel element failure rates led to increased radiation fields throughout the plant.
After a refueling outage, the licensee began a program to identify and remove temporary shielding installed on systems inside the containment building, but failed to do this in other plant areas. Improvements in the maintenance and design program would have prevented shielding installation without required 10 CFR 50.59 evaluations.
Failure to analyze for possible seismic / structural effects (both dynamic and static) of lead shielding on safety-related systems constitutes an unreviewed safety question. In regards to the above situation, safety-related systems were modified with additional shielding without supporting engineering evaluations to ensure system operability under design-basis event conditions.
Although it is focused on radioactive waste treatment systems, IE Circular No. 80-18, "10 CFR 50.59 Safety Evaluation for Changes to Radioactive Waste Treatment System", provides general guidance and clarification regarding the requirements of 10 CFR 50.59 (see HPPOS-086).
Regulatory references: 10 CFR 50.59
Subject codes: 5.3, 8.5