GoldSim Modeling for the
Options Analysis for the Smoky Site,
Nevada Test Site
Background
The operators of the Nevada Test Site (NTS) faced a problem:
It was discovered that two important power transmission lines in Area 8
of the NTS (see NTS map)
ran through the site of several aboveground nuclear tests,
where the ground surface is contaminated with a variety of radionuclides.
One test was a thermonuclear detonation, which distributed fission
products around the area, and other tests were hydrodynamic tests
(where the fissionable material does not actually fission), which
littered the area with bomb parts and actinides
(see map of alpha and 241Am contamination).
The area was fenced to prevent casual access, but the powerlines
(two are indentifed on the map as red lines) would still need to be maintained.
Furthermore, the area, like much of the NTS, is subject
to erosion and sediment transport in washes which periodically experience
flash floods. This means that any localized cleanup of a given wash
is likely to be recontaminated by the migration of upstream sediments
which may be contaminated.
The Problem
The problem faced by the NTS operators is how to maintain access to
the powerlines for maintenance or emergencies. Several options were
considered:
- Force powerline workers to suit up in protective gear
while working on the powerlines
- Clean up the ground surface under the powerlines
- Clean up the ground surface in the entire fenced area
- Clean up the ground surface in the washes
- Contain the contamination to prevent migration
- Move the power transmission lines and abandon the existing
ones
- Construct a causeway of clean fill dirt under the powerlines
- Do a combination of the above alternatives
- Do nothing
Each of these alternatives has costs and benefits associated with it,
and the job of Neptune and Company is to determine what those costs
and benefits are, and to rank the options available to the site operators.
The decision of which option to choose lies with the operator.
The Options Analysis
Neptune and Company constructed a GoldSim model to evaluate the
alternatives in a cost/benefit framework. This analysis involved an
assessment of the contamination, based on spatial data obtained from
flyovers and surface surveys, as well as the construction of a dose
model for the population and for individuals who would be involved
in surveys, remediation work, powerline maintenance, and site monitoring.
The dose to the inadvertent intruder is also considered.
Risk assessments are driven by DOE O 5400.5 for human health risks
and 10 CFR 835 for occupational exposure.
The costs of these various options was considered, as was the benefit
gained from each. Cost categories include
- As Low As Reasonably Achievable (ALARA) dose-based costs
- Price-Anderson Amendments Act (PAAA) fines
- Cleanup costs
- Transportation costs incurred in migration control
- Access control costs (fencing, signs)
- Cost of moving the powerlines
Since the contamination at the site is long-lived,
the risk associated with that contamination and the activities required
to monitor the site are carried into the distant future. Likewise, the
benefits gained from complete site cleanup and its lack of future costs are
considered, as is the potential for the imposition of fines for doing
nothing with the site. A
decision framework
was developed and implemented in GoldSim.
Go to Neptune's GoldSim page
Send comments regarding these pages to
John Tauxe
Last modified: 27 July 2004
