ALARA -Reply

[Charles Willis <CAW@nrc.gov>]

Mike,

The meaning of the ALARA principle depends on who you listen to and when.  The
ICRP says ALARA means optimization.  Optimization, as defined by the ICRP
publications, is not practicable.  Americans seem to take ALARA to mean
"anything that does not quite bankrupt the company," while the British seem to
believe it means "do not pay too much for this muffler."  As for your two
statements, statement number 2 is meaningless.  This is true because every
release of material (all material is radioactive) exposes everyone on earth; not
much, of course,  but your statement has no cut off.  It does not take many
radioactive atoms to produce a yocto-rem dose.

Statement number 1 seems pure LNTH application, which means that individual
doses are to be kept below whatever limits there are and the quantity to be
minimized is the collective dose equivalent.   If the concern were biological effects,
it might be better to concentrate on the dose rate, recognizing that when the NCRP
tried to find experimental evidence for or against a DREF, they could find no
effects for comparison where the dose rate was below 8 rad per day.

Charlie Willis
caw@nrc.gov