[ RadSafe ] Nuclear Gauges, "HIGHLY RADIOACTIVE?" and More on Ownership

[Geo>K0FF]

Nuclear Gauges, "HIGHLY RADIOACTIVE?"

Steve asked " The half-life of Cs-137 is 30 years, and the half-life of Am-241 
is 458 years.  Can either of these isotopes properly be characterized as 
"highly radioactive"?"

Well Steve, the term is a relative one at best, but not very quantitative. The term is not in the Nucleonics Dictionary, but 
High Radiation Area *IS* defined (>100 millirems , in 1 hour @ 30 cm from the source) 

A typical Troxler will hold:

1.48 GBq (40 mCi) Am-241:Be and a 0.296 GBq (8 mCi) Cs-137 source.

To some on this list, these are not significant activities. To others they are huge. To be sure, 
milliCuries of activity of any isotope are nothing to ignore or disrespect. 

(Am:Be) neutron sources have an energy of 5.48 MeV, RBE of  20, 
and the Am-241 alphas are RBE 20, Am-241 has a 59.5 keV gamma @ about 26% probability and the gamma  RBE is 1. while the 
Gamma Factor "Specific Exposure Rate Constant", is 0.31.

Cs-137 decays by beta emission and the RBE for betas is 1.
Ba-137m decays by IT and has a 32 keV @ 38% and the familiar 662 keV @ 90% (all probabilities rounded to next full %), again RBE 1, Gamma Factor 0.39997.

In a working system like a nuclear density gauge, the factors of TIME * SHIELDING * DISTANCE are 
optimized for minimal exposure to an operator. From that standpoint the radioactivity is nil.

Misuse of any industrial tool can be hazardous,  training is mandatory and safety is assured by procedure.

NRC Licensing. 
This is not a tutorial or walk-though step by step procedure to obtain a materials license. For that, contact you state ( if you are in an agreement state) or NRC regional office serving your non-agreement state. In Missouri, my state the person in charge of licensing is Patty Poelki in the Lisle IL regional office. The following facts were re-verified with her by telephone today:

All fee questions get directed to B. Brown in the HQ office.

License issuance, site inspections and administration are from the Lisle IL office ( for my state).

In the last 30 days pre-licensing site inspections are always required, in addition to other sweeping changes (probably in light of the recent publicity).

A good place to start gathering information is 
http://www.nrc.gov/reading-rm/

Be advised that NUREG 1556 Vol 1 is not up to date.

To see if you are in an agreement or non-agreement state, go to:
http://nrc-stp.ornl.gov/asdirectory.html

listed in this last link is the current status of all the states and the state contact persons. All states, agreement or non, have certain state regulations 
for many radioactive material and radiation creating machines etc. 
Regulation put into effect on 27 April 2007 have changed some of the regulation responsibilities back to the NRC, so be sure to contact your correct person.

NRC Regions and regional office contacts. 
http://www.nrc.gov/info-finder/region-state/



I must reiterate, the facts are;
NRC Materials License costs only $1200.00 USD and is good for 10 years. Prorated it costs $ 120.00 USD per year. After 10 years, the license renewal is free of fees.
There is a fee involved each year as a maintenance fee to the NRC, it is not a license renewal fee.The size of that fee depends on who you are, can be as low as $500.00 USD. At the time of new license application, you must provide the type of instrument(s) and the rad load activity, isotopes and type number. Further additional units are easily added by addendum, with no fees incurred.
An evaluator will help you to comply with the rules and make sure the type and number of sources are "reasonable".

Other out of pocket expenses are fees charged by companies to provide you with the mandatory services that are required by NUREG 1556 Vol 1, such as training, leak testing etc, as correctly pointed out by reader H. Dale Snowder in a previous post to these pages.
Many, if not all these services are provided with gauge purchase from Troxler.

references available by eMail

George Dowell
NLNL
New London Nucleonics Lab
56791 Rivere Au Sel Pl.
New London, MO 63459

GEOelectronics at Netscape.com

573-221-3418







>>Steven Dapra <sjd at swcp.com>
>>Subject: Re: [ RadSafe ] NRC issues License to phony company
>>To: Bob Casparius <caspar at aecom.yu.edu>, <radsafe at radlab.nl>
>>Message-ID: <5.2.1.1.1.20070712185205.009f90d0 at mail.swcp.com>
>>Content-Type: text/plain; charset="iso-8859-1"; format=flowed

>>July 12

        > >From an AP article (with no byline), datelined Washington, in 
>>today's Albuquerque Journal (p. A-6, for those who live in Albq.):

  >>       "The license that was obtained allowed for the purchase of up to 
>>five portable moisture density gauges widely used in construction, in which 
>>are encased small amounts of cesium-137 and americium 241, two highly 
>>radioactive isotopes.

  >>       "Individually, these devices pose little threat because of the 
>>small amount of radioactive material, radiation experts say.  Still, the 
>>devices require an NRC license to be purchased and must be closely 
>>safeguarded by companies that use them to avoid theft."

>>         The half-life of Cs-137 is 30 years, and the half-life of Am-241 
>>is 458 years.  Can either of these isotopes properly be characterized as 
>>"highly radioactive"?

>>Steven Dapra
>>sjd at swcp.com