[time-nuts] How dangerous if Rb lamp broken?

Thu Jul 11 01:12:30 UTC 2013

Thanks, Robert, for this detailed information.
Volker

Am 10.07.2013 21:01, schrieb Robert Atkinson:
> Hi Hui,
> This is a little off-topic for time nuts, but here goes. the
> Becquerel is a measurement of radioactivity, 1Bq being one decay per
> second. Bg/gm is specific activity so if you have 1g of material with a
> specific activity of 200Bq/g you will have 200 decays per second. We
> need to use this as not all the Rb in a lamp is Rb 87 and the weight
> quoted includes it all. The Sievert is a measurement of effective dose.
> It depends on time, quantity of radioactive material, type and energy of
>   radiation emitted, distance and the organ exposed. It is not a simple
> calculation or conversion. As Rb87 is a beta emitter with a maximum
> energy of 272 keV, it will only produce localised effects. externally it
>   will only cause skin exposure and you would need megabecquerels in
> direct contact to cause something like a sunburn. Anything else
>   would need internal exposure.
> Rb87 is of so little concern that the
> standard dose rate calculation program I use does not even list it.
> Chemically Rb is similar to potassium, K, which is essential to humans. 
>   Natural K contains 0.0117% of the radioactive isotope K40. A typical
> 70kg human male is 0.2%K so has more than 3000Bq of K40.  So if you
> swallowed 2mg of the Rb from a bulb AND the body absorbed ALL of it, the
>   total additional dose would be less than 0.1% of that you are getting
> from the natural K in your body. In practice it would be even less
> because your body would not absorb it all and that it did absorb would
> probably displace some K. Intact Rb cells cells have on detectable
> external radiation. My half gram estimate came from a web search of peer
>   reviewed articles.
> The US occupational ingestion limit is 1mCi or
> 37000Bq per year. Inhallation is twice that. US labs can discharge water
>   to the sewer with 370Bq/liter of Rb87 
> Rb cells are perfectly safe for all practical purposes. An injury from the broken glass is probably much more of a risk!
>
>
> HTH,Robert G8RPI.
>
>
> ________________________________
>   From: Hui Zhang<ba6it at 163.com>
> To: Robert Atkinson<robert8rpi at yahoo.co.uk>; Discussion of precise time and frequency measurement<time-nuts at febo.com>
> Sent: Wednesday, 10 July 2013, 14:53
> Subject: Re:Re: [time-nuts] How dangerous if Rb lamp broken?
>
>
>
> Hello Robert:
> I am a little confuse how exactly much Rb87 in a bulb? Some people say
> that it's couple millgram,  but you tell
> me it's half a millgram, which is ture?
> You message is good new to me, it let me relax, but I don’t
> understand Bq/gram unit, would you please convert it to mSV unit, I can know
> the how many mSV of human is safety by search by internet. I mean in extreme
> situration, if all Rb87 of buld sprinkled in my table, how many exposure value
> will I accepet in 24 Hour?
> I found some people (other electronics fan) wrote a formula about
> Rb87 radioactivity calculation, that is:
> 1mg Rubidium * 27.835 * 0.27835 * 6.02 *10^23 /
> 87/4.88/10^10/2/365/24/3600*1=625.
> So, decay energy=0.283MeV, about 600 electron per second, Is this calculation
> correct?
>   
> 27.835=Percent of Rb87
> 6.02*10^23 = Avogadro's constant
> 87= Atomic weight
> 4.88*10^10== Half time of Rb87 (Year)
> 2 = Rb87 decay to half
> 365 = day of year
> 24 = hour of day
> 3600 = second of hour
>   
>    I
> am very glad to read many relay of my email, I want say thanks for everyone. As
> you said why people be afraid of Rb87 but not other things, I think maybe
> because we don’t understand it. Such as, I don’t afraid of RF exposure, because
> I know it, I am a HAM and learned many RF exposure knowledge, but of atom and
> radioactivity, I have only poor knowledge.
>   
>   
> Thanks everyone again, this is amazing mail-list. Say sorry for my poor English.
>   
> Hui
>
>
> At 2013-07-09 19:40:50,"Robert Atkinson"<robert8rpi at yahoo.co.uk>  wrote:
>    
>> Hi Hui,
>> Most bulbs use a mix of Rb87 and Rb85 with an activity of around 1500 Bq/gram with less than half a millgram in a typical bulb, that's less than a Bq per bulb (about 20 picocuries). You will get more ardiation from using low sodium salt (potassium chloride) on your food. Potasium is essential for life and Rb is chemically similar.
>> In short don't worry.
>> Robert G8RPI (also a geiger "nut" and collector of radioactive material)
>>
>>
>> ________________________________
>> From: Hui Zhang<ba6it at 163.com>
>> To: Discussion of precise time and frequency measurement<time-nuts at febo.com>  
>> Sent: Tuesday, 9 July 2013, 5:07
>> Subject: [time-nuts] How dangerous if Rb lamp broken?
>>
>>
>> Dear Group:
>>      I have four compact Rb Stanard, but I am worried about what if my Rb lamp broken in accident someday? How dangerous of this situration? Is Rb87 came out from Rb lamp will be a disaster? You know I haven't any beta rays detect instrument.
>>
>>
>> Hui
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