Page 355 - Beyond Decommissioning

Case studies of nuclear redevelopment 331

legacy hazardous materials and a legacy storage unit were discovered during decon-
tamination activities. Legacy safety documentation and characterization for surplus
facilities may not be accurate, true, and complete. The creation of safety documenta-
tion that relies heavily upon prior documentation and diligent surveillance of observ-
able facility contents and conditions will not completely eliminate the potential for
unknown hazards to be identified when hands-on and/or intrusive decontamination
work begins. Thus, appropriate conservatism in the development of work controls
combined with a questioning attitude during hands-on and/or intrusive decontamina-
tion work is essential to complete work safety.

7.14.3 Establish credibility prior to relying too heavily on
historical data, Oak Ridge Site, United States [US
Department of Energy, lessons learned data base #:
B-2005-OR-BJCETTPDD-1101 (available upon DOE
authorization)]
Problem encountered: During the performance of D&D work activities at K-1420,
liquid was discovered in pipes that were thought to have been previously drained,
based on prior documentation presented during transition. The current Nuclear Crit-
icality Safety Determination (NCSD) and Safety Basis documents were developed
based on the premise that all systems had been drained of all solutions and thus by
nature of the process criticality was incredible. With the discovery of liquids in pro-
cess piping the criticality is no longer incredible.
Analysis: The previous documentation for the facility had been accepted from
the previous contractor as adequate with limited analysis to verify the credibility of
this documentation. The previous contractor abandoned the facility in place after
bankruptcy.
The piping system from which the liquid was drained had been air gapped by the
previous contractor and left in place for several years. Historical documentation stated
any product material in columns/piping/equipment was assumed to have evaporated to
sludge. Other historical documentation, 1 month later, stated residual solution
remained in piping and tanks. Contemporary characterization did not include charac-
terization of pipes. Authors of the contemporary safety basis documents chose to rely
most heavily on the historical documentation that stated any product in columns/pip-
ing/equipment are assumed to have evaporated to sludge.
Lessons learned: Historical data should be challenged and verified to the extent
possible before relying on the information to develop safety basis documentation.
Contemporary analyses and inspections may yield results different from historical
records as to what should be expected in structures, systems, and components
abandoned in place for years. In detail:
– the liquid collected should be analyzed to determine if any knowledge can be gained from
knowing the identity of the liquid;
– the work instructions should identify the size/type of container used to collect liquids in the
future to avoid any hazardous situations in the future;