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330 Beyond Decommissioning

requires the cessation of affected activities when underground items not adequately
identified by as-built drawings are encountered. The construction workers recognized
the hazards and stopped work immediately. Plant personnel were contacted for addi-
tional information, prior to work resumption.
Analysis: In this circumstance, a greater potential existed for personnel contamina-
tion from the Category 3 soil than was originally thought to have existed. The CM had
a work control process in place to address and account for changes in field conditions
such as inadequate soil characterizations and the legacy problem with as-built draw-
ings not being updated. This work control process also allowed the CM to stop
affected field activities until the unidentified underground items could be properly
identified and characterized.
Lessons Learned: Potential accidents such as human injury or fatality, equipment
damage, and/or costly project delays are avoided when a work control process is
established to compensate for field work conditions which often differ from the initial
site characterization, as-built drawings, etc.

7.14.2 Discovery highlights the potential of encountering
unknown/unanticipated materials and hazards, Oak Ridge
Site, United States [US Department of Energy, lessons
learned data base #: B-2004-OR-BJCBOP-1202 (available
upon DOE authorization)]

Problem encountered: Subcontractor personnel were decontaminating horizontal sur-
faces in a surplus facility in an effort to reduce the ongoing surveillance and mainte-
nance costs for a development laboratory awaiting eventual decontamination and
demolition. While wiping down a storage shelf, they discovered hidden compartments
and a lead storage array. Although the top of each shelf was empty, the decontami-
nation workers discovered that the top shelf horizontal surface was ajar and moved
when it was wiped. Their continued investigation revealed that the previously caulked
and painted top surfaces were lids which could be removed. Removal of the lids
exposed a shielded storage array for each shelf of 2-in. (5cm) diameter by 6-in.
(15cm) or 8-in. (20cm) deep storage wells and two troughs.
Analysis: The discovery of lead and abandoned items contained within the array
resulted in an inadequate safety analysis for the facility which was resolved through
submission of a revised Documented Safety Analysis (DSA) and DOE-approval via a
revised Safety Evaluation Report for the facility.
Performance of the accident analysis with the increased lead inventory resulted in a
threefold increase in the lead exposure level to on-site workers and doubling of the
exposure to off-site receptors. This increase resulted in increasing the facility chem-
ical hazard classification from low to high. The discovered radioactive materials,
although not specifically considered in the DSA, were nonetheless bounded by the
25% extra factor conservancy added to the known inventory resulting in a very
low increase in risk due to the radiological material discovered.
Lessons learned: After performing maintenance and surveillance of a radiologi-
cally contaminated isotopes development laboratory for approximately 6 years,