Re: 10CFR20 mistake?

[Jack Couch <jgcouc@PLANETX.BLOOMU.EDU>]

At 07:13 AM 4/5/01 -0700, Sandy Perle wrote:



___Jack Couch___

>> 20.2202 (a)(1)(iii) "A shallow-dose equivalent to the skin or extremities

>> of 250 rads(2.5 Gy)..."

>> Note the units used here for shallow-dose equivalent. It is the same in

>> earlier editions of 10CFR20. In (b)(1)(iii) the units are in rems (Sv). 

>> 

>> Do you suppose there is a reason behind the difference in units, or is it

>> just another governmental boo-boo? 

>

___Sandy Perle___

>This is not an ewrror. It;s simply a degree of the exposure and the 

>definition, as defined below:

>

>§20.1004 Units of radiation dose.

>(a) Definitions. As used in this part, the units of radiation dose 

>are:

>Gray (Gy) is the SI unit of absorbed dose. One gray is equal to an 

>absorbed dose of 1 Joule/kilogram (100 rads).

>Rad is the special unit of absorbed dose. One rad is equal to an 

>absorbed dose of 100 ergs/gram or 0.01 joule/kilogram (0.01 gray).

>Rem is the special unit of any of the quantities expressed as dose 

>equivalent. The dose equivalent in rems is equal to the absorbed dose 

>in rads multiplied by the quality factor (1 rem=0.01 sievert).

>

___Jack Couch___

Sandy, that's exactly my point. To reiterate, 20.2202 (a)(1)(iii) expresses

(shallow) dose equivalent, not in SV and rem, but in Gy and rad. Later, in

20.2202 (b)(1)(iii) (shallow) dose equivalent is given correctly in Sv and

rem.



regards,

Jack











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