RE: Thorium in urine

["Christoph Hofmeyr" <Christoph_Hofmeyr@NNR.CO.ZA>]

Randy,

My copy of ICRP 68 seems to be evading me, but ICRP 54, p201 gives for 1

micron AMAD class W (M) ALI 40 Bq,  DAC 2E-2 Bq/m^3;   and for class Y (S)

ALI 100 Bq,  DAC 4E-2 Bq/m^3 for Thorium-232.   You are quoting for 5

micron AMAD and 50 mSv annual dose limit, judging from IAEA Safety Series

115 p150, which should correspond with ICRP 68.  So actually the factor is

more like 17 if you compare the larger particles.  My original message

should have specified 1 micron AMAD.

Chris Hofmeyr

chofmeyr@nnr.co.za



You wrote:

Chris,



I'm believe the ICRP 68 DAC for Thorium 232 Type S is 1.7 Bq/m^3 and 0.72

Bq/m^3 for type M.



Randy Redmond

BWXT Y-12 L.L.C.

Y-12 National Security Complex

Radiological Control Organization

Email:  rxq@Y12.doe.gov





Originally I wrote:

> From:         Christoph Hofmeyr [SMTP:Christoph_Hofmeyr@NNR.CO.ZA]

> Sent:         Wednesday, April 04, 2001 10:58 AM

> To:           radsafe@list.vanderbilt.edu

> Subject:           Re: Thorium in urine

>

> RADSAFERS,

> Isn't Thorium-232  one of the radionuclides which miraculously has lost a

> lot of its radio-toxicity between ICRP 54 and ICRP 68, a factor of almost

> 30, if I am not mistaken (ALI of 40 Bq for 50 mSv went to 470Bq for 20

> mSv)?

> Chris Hofmeyr



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