Regulation of radiation machines.

[Bruce Pickett <SHEA136@kgv2.bems.boeing.com>]

 I am posting the following information and questions for some friends who
 don't have access to RADSAFE.

   Bruce Pickett
   bruce.d.pickett@boeing.com
   --------------------------

 To quote from our State's radiation control regulations: "'Radiation' means
 alpha particles, beta particles, gamma rays, x-rays, neutrons, high-speed
 electrons, high-speed protons, and other particles capable of producing ions."

 Again, quoting from the State regs: "Electronic equipment that produces
 radiation incidental to its operation for other purposes is exempt from the
 registration and notification requirements of this part, providing the dose
 equivalent rate averaged over an area of 10 square centimeters does not exceed
 0.5 mrem per hour at 5 cm from any accessible surface of such equipment"; and,
 "Domestic television receivers are exempt from the requirements of this
 chapter."

 We requested an interpretation of the exemptions to the regs, and what we got
 stated: "in describing exemptions, the key is that if the primary purpose and
 intent of the product is to produce radiation, then it must be registered, OR,
 as described, it incidentally produces the described level. Therefore electron
 microscopes and electron beam welders require registration since they are
 meant to produce a beam of electrons."

 VDTs (not domestic television receivers), electron beam welders, electron
 microscopes, and electronic tubes all MUST produce electron beams in order to
 operate, and each generates its electron beam in a vacuum. The electron beam
 itself cannot penetrate through the machine enclosure, and, if you break the
 vacuum by opening the enclosure, the electron beam shuts down; so as a primary
 radiation source, electron beams themselves would not seem to be a hazard. But
 of course, upon striking mater, electron beams can certainly produce other
 radiations such as x-rays. These radiations would be incidental to the
 operation of the machines and would be exempt if less than the specified
 limits. However, under the aforementioned interpretation, simply generating an
 electron beam requires registration of those machines.

 Here are our questions:

 #1 - What energy electron beam does it take to have "high-speed electrons"?

 #2 - If a machine generates a beam of electrons as part of its intended
 operation, for example, as in a video display terminal to excite the phospors,
 is the beam of electrons considered to be radiation?

 #3 - Does the same apply for electron beam welders which use electron beams to
 heat materials and weld them together, or electron microscopes which use
 electron beams to scan microscopic structures, or high voltage electronic
 tubes to amplify signals?

 #4 - Should machines be regulated as radiation machines simply because they
 generate internal electron beams, or would the electron beams and associated
 x-rays be considered radiation incidental to the operation of the machines and
 exempt if less than the specified limits?