Environmental Engineering Reference
In-Depth Information
Care.must.be.taken.to.not.increase.existing.heat.loads..The.major.initiative.is.to.
reduce.the.heat.stress.that.exists.because.the.physical.problems.that.workers.face.due.
to.heat.exposure.can.be.deadly.
IonIzIng rAdIAtIon
Ionizing.radiation.has.always.been.a.mystery.to.most.people..Actually,.much.more.is.
known.about.ionizing.radiation.than.the.hazardous.chemicals.that.constantly.bom-
bard. the. workplace.. After. all,. there. are. only. four. types. of. radiation. (α-particles,.
β-particles,.γ-rays,.and.neutrons),.whereas.there.are.thousands.of.chemicals..There.
are. instruments. that. can. detect. each. type. of. radiation. and. provide. an. accurate.
dose-received.value..This.is.not.so.for.chemicals,.where.the.best.that.we.could.hope.
for.in.a.real-time.situation.is.a.detection.of.the.presence.of.a.chemical.and.not.what.
the.chemical.is..With.radiation.detection.instruments,.the.boundaries.of.contamina-
tion.can.be.detected.and.set,.while.detecting.such.boundaries.for.chemicals.is.nearly.
impossible.except.for.a.solid.
It.is.possible.to.maintain.a.lifetime.dose.for.individuals.exposed.to.radiation..Most.
workers.wear.a.personal.dosimeter.that.provides.a.check.on.the.levels.of.exposure..
The.same.is.impossible.for.chemicals.where.no.standard.unit.of.measurement,.such.
as.the.roentgen.equivalent.in.man.(rem),.exists.for.radioactivity.in.chemicals..The.
health.effects.of.speciic.doses.are.well.known:.for.example,.20.to.50.rems—causes.
minor.changes.in.blood,.60.to.120.rems—vomiting.occurs.but.no.long-term.illness,.
or.5,000.to.10,000.rems—certain.death.within.48.hours..Certainly.radiation.can.be.
dangerous,.but.exposures.can.usually.be.controlled.by.one.or.a.combination.of.three.
factors:.distance,.time,.and/or.shielding..Certainly.distance.is.the.best.because.the.
amount.of.radiation.from.a.source.drops.off.quickly.as.a.factor.of.the.inverse.square.
of. the. distance;. for. example,. at. 8. feet. away,. the. exposure. is. 1/64. of. the. radiation.
emanating.from.the.source..As.for.time,.many.radiation.workers.are.only.allowed.
to.stay.in.a.radiation.area.for.a.limited.length.of.time,.and.then.they.must.leave.that.
area..Shielding.often.conjures.up.lead.plating.or.lead.suits.(similar.to.when.x-rays.are.
taken.by.a.physician.or.dentist)..Wearing.a.lead.suit.may.seem.appropriate.but.the.
weight.alone.can.be.prohibitive..Lead.shielding.can.be.used.to.protect.workers.from.
γ-rays.(similar.to.x-rays)..Once.they.are.emitted,.they.could.pass.through.anything.in.
their.path.and.continue.on.their.way,.unless.a.lead.shield.is.thick.enough.to.protect.
the.worker.
For.β-particles,.aluminum.foil.will.stop.their.penetration..Thus,.a.protective.suit.
will.prevent.β-particles.from.reaching.the.skin,.where.they.can.burn.and.cause.sur-
face.contamination..α-Particles.can.enter.the.lungs.and.cause.the.tissue.to.become.
electrically.charged.(ionized)..Protection.from.α-particles.can.be.obtained.with.the.
use.of.air-purifying.respirators.with.proper.cartridges.to.ilter.out.radioactive.par-
ticles..Neutrons.are.found.around.the.core.of.a.nuclear.reactor.and.are.absorbed.by.
both.water.and.the.material.in.the.control.rods.of.the.reactor..If.a.worker.is.not.close.
to.the.core.of.the.reactor,.then.no.exposure.can.occur.
Ionizing.radiation.is.a.potential.health.hazard..The.areas.where.potential.expo-
sure. can. occur. are. usually. highly. regulated,. posted,. and. monitored. on. a. continu-
ous.basis.(see.Figure 23.8)..There.is.a.maximum.yearly.exposure.permitted..Once.
