The primary control for contamination in a plutonium plant is the facility design.
Contamination is confined primarily by enclosing the process areas and using controlled
ventilation systems. Appendix C of this guide addresses the different levels of confinement
in a plutonium facility. The design objective for the confinement system is to essentially
prevent or minimize exposure of plant personnel and the public to airborne contamination.
To ensure that this objective is met, additional attention should be given to air
contamination control, surface contamination control, and personnel contamination control.
Radiological controls for the workplace should ensure that radionuclides are contained and
handled properly and that intakes, if they occur at all, are negligible to the extent achievable
with state-of-the-art technology. However, much of the current effort involves
decommissioning of no-longer-needed production facilities. The lack of engineered
controls or the systematic removal of existing controls during the decommissioning process
introduces a completely different set of circumstances that requires special attention for
adequate contamination control and worker and public protection.
AIR CONTAMINATION CONTROL
To achieve the design objective of preventing (or at least minimizing) internal exposure of
plant personnel, airborne contamination must be confined to process enclosures which have
adequate air cleaning systems. Because both equipment and personnel errors can
compromise designed protection and because older facilities may already have unconfined
plutonium, air monitoring and other contamination control measures are needed.
Experience has shown that the most common route for inadvertent plutonium deposition in
man is by inhalation even though intakes may also occur by accidental ingestion or by
wound contamination. In facilities being decommissioned, the use of temporary
containment structures, interim ventilation systems, and administrative controls such as
protective clothing and respirators may be required to replace engineered systems.
10 CFR 835.1002 requires that for the control of airborne radioactive material, the design
objective shall be, under normal conditions, to avoid releases to the workplace atmosphere
and in any situation, to control the inhalation of such material by workers to levels that are
ALARA; confinement and ventilation shall normally be used. See Appendix C for Facility
Note: The use of ventilation systems may require the approval of Facility Criticality Safety
personnel because these systems may concentrate fissionable material.
4.1.1 Internal Versus External Dose Philosophy
The overall goal of radiological protection is to minimize the total dose to the
individual. However, because of the difficulties and cost of an adequate internal
dosimetry program for plutonium exposure, it is best to avoid all internal exposures
during routine operations and anticipated abnormal events by facility design features
and personnel protective equipment. As stated above, this is an extremely challenging
goal for those facilities in environmental remediation. The conditions encountered in
decommissioning and environmental restoration will typically place a heavy reliance
on administrative controls.