[time-nuts] Cesium Clock Avialable

Poul-Henning Kamp phk at phk.freebsd.dk
Sat May 19 16:43:00 EDT 2018

In message <B17ED93D-0178-456F-B448-A93697E44F10 at n1k.org>, Bob kb8tq writes:

>Cs is classified rightly as a hazardous substance. Transporting and shipping 
>hazardous stuff is indeed regulated (as it should be). For various silly reasons
>the minute amount of Cs inside a virtually indestructible container in a Cs 
>standard  falls into the hazardous category. 

The reason for this is actually not very silly.

Very potent Cs137 sources are used in borehole characterization in
disturbingly high numbers, and they are licensed and tracked by the
relevant national regulatory agency, NRC.gov in the USA.

The HAZMAT regulations used to be different for Cs137 (nuclear
concerns) and Cs133 (chemical concerns) but smartasses in the oil
industry discovered lower costs if they "couldn't remember the

I belive HP used to have an exemption for shipping factory new
CS-tubes *from* their factory, but not for shipping new or used
tubes *to* their factory, because customers could not be trusted
to pack according to spec.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.

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