Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 83-64
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
September 29, 1983
Information Notice No. 83-64: LEAD SHIELDING ATTACHED TO SAFETY-RELATED
SYSTEMS WITHOUT 10 CFR 50.59 EVALUATIONS
Addressees:
All nuclear power reactor facilities holding an operating license (OL) or
construction permit (CP).
Purpose:
This information notice is provided to inform licensees of an event at a
pressurized water reactor (PWR) where significant quantities of lead
shielding were installed on safety-related systems without a proper
engineering evaluation as required by 10 CFR 50.59. Licensees are devoting
increased attention and resources to reduce radiation fields in an effort to
minimize workers' exposure. The NRC encourages these ALARA efforts; however,
this event and other similar occurrences illustrate a need to reemphasize
the requirements of 10 CFR 50.59. No specific action or response is
required.
Description of Circumstances:
During a routine inspection at the Maine Yankee Atomic Power Station on June
8, 1983, an NRC inspector noted that portions of safety-related piping
(three-inch hydrogenated waste header pipe) in the primary auxiliary
building was covered with lead shielding. Discussions with the plant
engineering staff revealed that licensee safety evaluations to support this
plant modification had not been performed. Since the licensee had no formal
control mechanism to govern the installation, use, and accounting of
temporary shielding (in the 1974-75 period), no records existed to document
the dates and locations of shielding installations. The shielding was placed
on plant systems during the 1974-1975 period when high fuel element failure
rates led to increased radiation fields throughout the plant.
After the 1982 refueling outage, the licensee had initiated a program to
identify and remove temporary shielding installed on systems inside the
containment building, but failed to broaden this effort to other plant
areas. Recently implemented improvements in the maintenance and design
program would currently prevent shielding installation without required 10
CFR 50.59 evaluations. The controls and procedures currently in place as
part of the facility Quality Improvement Program should prevent any
reoccurrences.
8308300349
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IN 83-64
September 29, 1983
Page 2 of 3
In response to a Regional Confirmatory Action Letter, the licensee initiated
the following corrective actions to identify, the extent of the problem and
to resolve the safety concerns:
1. Inspection of all safety-related piping in radiological controlled
areas outside containment to identify any shielding affixed to or which
could affect these systems (e.g., lead insecurely attached to non-
safety-related system such that it might fall onto a safety-related
system).
2. Removal of all identified shielding and documentation of location and
quantity.
3. Identification of any system degradation problems evident after
shielding removal.
4. Description and verification of the effectiveness of actions taken
during and after the 1982 refueling outage to identify and remove lead
shielding from piping inside containment building.
5. Performance of inspections and engineering analyses of the affected
systems to ensure their operability under design-basis event
conditions.
Detailed inspections were conducted in all accessible areas outside
containment and the licensee identified 18 to 20 locations where quantities
of lead shielding weighing between 10 and 380 pounds had been installed. By
June 21, 1983 all the identified lead shielding had been removed from the
safety-related systems. Because of improved fuel integrity performance,
radiation surveys conducted after the shielding was removed indicated only
two or three of the affected locations would still need any additional
shielding. Since only cursory inspections were conducted inside containment
because of high radiation dose rates, system walkdowns inside containment
will be performed during the next unscheduled plant outage. The licensee
found no visual evidence of permanent degradation to piping or its supports.
Any future permanent shielding modifications will be handled as design
changes. The licensee also plans to develop a program for control of
temporary shielding. Since the temporary shielding had not been readily
discernable from other pipe coverings/surroundings, brightly colored
temporary shielding materials will be used to enhance identification. At the
request of NRC's Region I, the licensee agreed to check the concrete anchor
bolt pre-load torque on the piping supports for the affected systems.
Discussion:
Failure to analyze for possible seismic/structural effects (both
dynamic/static) of lead shielding on safety-related systems constitutes an
unreviewed safety question. Maine Yankee safety-related systems (e.g.,
safety injection trains) were modified with additional shielding without
supporting engineering evaluations to ensure system operability under
design-basis event conditions.
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IN 83-64
September 29, 1983
Page 3 of 3
Although focused on radioactive waste treatment systems, IE Circular No.
80-18, "10 CFR 50.59 Safety Evaluation for Changes to Radioactive Waste
Treatment Systems," provides general guidance/clarification regarding the
requirements of 10 CFR 50.59. If you have any questions regarding this
matter, please contact the Regional Administrator of the appropriate NRC
Regional Office, or this office.
Edward L. Jordan, Director
Division of Emergency Preparedness
and Engineering Response
Office of Inspection and Enforcement
Technical Contact: J. E. Wigginton, IE
(301) 492-4967
Attachment:
List of Recently Issued IE Information Notices
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