RE: 38,222CPM hope this helps

["Frank Scarano II" <frank.scarano@nist.gov>]

All phosphate rocks have a small amount of uranium present as an

impurity, and therefore are very mildly radioactive. A sample of BG4

phosphate rock was recently reported to be radioactive and it was

therefore decided to compare its level of radioactivity alongside a

series of other "reactive" phosphate rocks to determine whether the

levels in BG4 were significantly higher than is usual.



The determinations were performed using a Geiger counter. A large bag of

BG4 was found to have a radioactivity level above background but not of

a high enough level to be calculated. When six 500g containers were each

filled with one of the six sources chosen- Arad, BG4, Egyptian, Gafsa,

North Carolina, and Sechura - there was no radiation which could be

detected above background in any instance. Therefore levels of radiation

in phosphate rocks are very low and hardly discernible above background.



This is consistent with a simple calculation based on the level of

uranium in the phosphate rocks (107 mg per kg in BG4). Assuming a level

of 100mg per kg in the form of U-238 (99.3% abundance) there should be

1200 disintegrations per minute per kg, compared to a typical background

figure of 50-100 in the atmosphere. Therefore it is natural to expect a

small level of radiation in a bulk sample of a phosphate rock but this

is of insignificant proportions. 



In a second set of experiments some natural rock samples were tested but

these also showed minimal levels of radiation. A household smoke alarm,

a "First Alert Model SA67DCAUS", produced a radiation level of at least

ten times (and probably closer to 100 times) the predicted maximum

amount of radiation from BG4 phosphate rock. There is a warning

statement on the label of the smoke alarm which states that it contains

radioactive Americium 241 but there is no suggestion of high levels of

radiation in the product. On this basis any radioactivity from BG4

phosphate rock could not be considered harmful.





Thanks

===============================

Frank C. Scarano II, Health Physics Technician 

Nist Center for Neutron Research

100 Bureau Drive, stop 3543  

Building 235 Room A 132 

Gaithersburg, MD 20899-3543 

Phone:301-975- 5811

=====================================

"The atom bomb was no 'great decision.' 

It was merely another powerful weapon 

in the arsenal of righteousness." 

President Harry Truman 



-----Original Message-----

From: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu] On Behalf Of

NiagaraNet@aol.com

Sent: Wednesday, June 11, 2003 11:33 AM

To: radsafe@list.vanderbilt.edu

Cc: NiagaraNet@aol.com

Subject: 38,222CPM





Hey folks:



Just a quick question; What type of rock would exhibit 38,222CPM?

Could this be a rock with a vein of ore such as Uranium (any variety)?

Could this rock be from Western New York State?

Would this "rock" be considered radioactively "hot" and would it present

a 

danger say if handled and then went to lunch without washing ones hands?

How would I properly dispose of this specimen?



Thanks for your opinions/expertise.



LR (now I'm "masking" my identity:*)

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