Introduction to Health Physics: Fourth Edition - Ruang Baca FMIPA UB

590 CHAPTER 11
Laundering contaminated protective equipment is a complex operation. It requires
knowledge of the mechanisms of cleaning and of the effects of the cleaning
agents on the composition and construction of the protective clothing. For most
isotope laboratories, the simplest method for dealing with contaminated protective
clothing is to rent the protective clothing from a commercial supplier and to return
the contaminated clothing to the supplier. For those installations that do their
own laundry, ordinary laundering procedures, using sodium hexa-meta-phosphate
or sodium ethylene-diamine-tetra-acetic acid (Na-EDTA) added to the wash water
may facilitate the removal of the contaminants. After laundering, the protective
clothing should be monitored to ascertain that it has, in fact, been decontaminated
to some previously determined limit. If a piece of protective clothing is unusually
or very severely contaminated, it may be simpler to dispose of the item as low-level
radioactive waste (LLRW) rather than to try to decontaminate it. Unless the wash
water meets regulatory requirements for discharge into the sanitary sewer system
(such as 10 CFR 20, Appendix B, Table 3), it must be treated as LLRW.
Control of the Worker: Respiratory Protection
When a worker is likely to be exposed to airborne radioactivity, respiratory protection
must be considered. According to as low as reasonably achievable (ALARA)
requirements, the sum of the internal and external doses must be minimized. Wearing
a respirator decreases a worker’s efficiency by about 20–25%. Thus, if exposure
to airborne radioactivity occurs simultaneously with external radiation exposure, an
ALARA-based decision must be made regarding the use of a respiratory protective
device, as explained in Chapter 8.
Medical Assessment
It must be strongly emphasized that a worker must be medically approved for respirator
use before being allowed to put on a respirator or being fitted for one.
Wearing a respirator effectively increases the volume of the upper respiratory tract,
thereby decreasing the volume of air that reaches the deep respiratory tract (where
gas exchange occurs). To compensate for this decreased air supply, the body’s homeostatic
mechanisms increase the respiratory rate and the rate of blood flow through
the lungs. These rate increases lead to increased demands on the heart muscle. If
the worker’s cardiovascular and respiratory systems are in good health, then these
increased cardiac demands are safely met. On the other hand, if the worker has
an impaired cardiovascular system, the heart may not be capable of meeting this
increased demand and a heart attack may ensue. For this reason, a worker who may
have to wear a respirator on the job must be tested and approved for respirator use
by a qualified physician before he or she is allowed to use a respirator.
Respiratory Protective Devices
The exact type of respiratory protective device that may be required depends on
the nature of the airborne contaminant. Respiratory protective devices may be used only
for those hazards for which they are designed. Half-mask or full-mask facepieces must
not leak and must fit properly. Accordingly, the wearer of a respirator must be fittested
before a respirator is assigned. Respiratory protective devices for radiological
protection may be classified into several major categories, as shown in Table 11-3.