Decontamination (DECON)

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiation Protection in Uranium Facilities

scoping meetings may be held. Similar actions may be taken to determine the applicable

decommissioning criteria and the alternatives to be considered.

Whether or not a formal scoping meeting and EIS are used, it will be necessary to define the D&D

options to be considered. Most of the analysis effort should be expended on those options that fulfill the

absolute criteria so they can be ranked relative to the other high-value criteria. General options would

typically include the following, which are taken from NUREG-0586, Final Generic Environmental Impact

Statement (GEIS) on Decommissioning of Nuclear Facilities (NRC 1988):

a. Decontamination (DECON) - Decontamination is the alternative in which contaminated

equipment, structures, and portions of a facility are physically removed from the site or their

radioactive contaminants are removed by chemical or abrasive means. This alternative is the

preferred approach to decommissioning uranium-contaminated facilities.

b. Safe storage (SAFSTOR) - SAFSTOR is sometimes referred to as "deferred decommissioning,"

the alternative in which nuclear facilities are placed and maintained in such a condition that the

structure and contents can be safely stored and eventually decommissioned. In preparing a facility

for SAFSTOR, the structure is left intact, but all nuclear fuels, radioactive fluids, and wastes are

removed from the site. This alternative is generally considered when the following conditions

occur:

1. Low-level waste disposal capacity is inadequate to implement DECON.

2. An adjacent operating nuclear facility would be adversely affected if the DECON alternative

were implemented.

3. A positive benefit would be derived through a limited period of radioactive decay. A cost-

benefit analysis should be performed, comparing totalcost and radiation exposure resulting

from DECON versus SAFSTOR. Then, a decision should be made whether any additional

costs incurred for the SAFSTOR alternative are justified by the dose savings. Due to the long

half- lives of uranium isotopes, radioactive decay is not a viable reason for using the

SAFSTOR D&D option.

c. Entombment (ENTOMB) - The entombment alternative involves removing all nuclear fuels,

radioactive fluids, and wastes from the site and encasing all structural and mechanical materials and

components not decontaminated to acceptable levels in a structurally long- lived material, such as

concrete. The entombed structure is maintained under appropriate continued surveillance until the

radioactivity decays to a level permitting unrestricted release of the facility. The maximum

allowable time in entombment should be less than 100 years. Due to the long half- lives of uranium

isotopes, entombment is not a viable option for decommissioning of uranium-contaminated

facilities.

d. The no -action alternative, as required by NEPA - In decommissioning, this is normally

considered the "walk away" option.

Conversion of a facility for alternate nuclear or other controlled use has sometimes been considered a

decommissioning mode; however, it is not truly decommissioned unless conversion involves removal of

all radioactive material. Final disposition, when it occurs at the end of the new use, should consider the

residual radioactivity onsite.

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