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*long* CD instrument info
Here's the Civil Defense instrument information I said I'd post. I
apologize for the length. I clipped out names, phone numbers and email
addresses from the postings. Thanks to everyone who provided information,
and if anyone really can find a source to get these meters for free, please
let me know!
Thanks,
Phil
Los Alamos Radiation Consultants
505.920.9712
laradcon@lanl.gov
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Texas A&M has quite a few of these that we are refurbishing and giving to
high school teachers. All the ones we have worked with have been GM's. Our
experience is that only about a third of them work as-is. With a little
effort (clean battery contacts, replace GM tube, replace meter, etc.) about
half of them will work. The rest require significant disassembly,
troubleshooting, and repair to get them working, if ever. These are mostly
used for spare parts, especially for the tubes. The success rate also
depends on where you obtain them. Some sources (different state and federal
emergency management agencies mostly) have taken better care of them than
others.
The cable from the box to the probe tends to be the weak link, so as long as
you are careful not to dangle the probe from the cable or pull on it, they
will continue to work fine. The rest of the detector assembly is rather
robust.
We have not attempted to calibrate them since they are intended to be used
only for demonstration and to show relative magnitudes.
I don't think the US government is buying any of them anymore. We have
obtained ours from agencies that are surplusing them because they don't want
to spend the money to store them anymore.
I don't know of a website that provides any information.
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See the following link and then click on the picture of the meter.
http://www.tdh.state.tx.us/ech/rad/pages/RADINST.HTM
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There are a full suite of CD meters. The manufacturer was Victoreen for most
of them. These were the CDV-700, CDV-715, etc.
The GM meter has a small windowed GM tube. Efficiency is pretty low. but it
works. Good for demos and for thermo-nuclear warriors. The Ion chambers also
work but their efficiency is also low. Watch out because there are 2 models,
one is a 0-5 R/hr readout and the other is a 0-5 mR/hr readout. Both have
some scale multiplier settings. (What's a factor of a thousand among
friends...) The CD kit usually comes with a few pencil dosimeters and a
charger. They also work, but as with all pencil dosimeters, I've worked
with, if you don't like the reading, just shake it until you get a reading
you like.
I've got an old kit given to me my NE CD for show and tell demos, I can
calibrate it, but I would not use the equipment on any work site where I
wanted to maintain a decent reputation. Kit also had some CD "in case of a
nuclear explosion in your neighborhood..." info overhead slides, a fallout
calculator and a "time until you can leave the shelter" chart, and a
flashlight (green).
CAVEAT, the GM counters have a Cs-check source built into the housing. watch
out for disposal problems.
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There is a group of recreationally interested persons who have an internet
mailing list, and it's called the CDV700 club... they collect, refurbish,
and play with these types of meters and know lots more than anyone I know.
Getting info from them requires either just snooping on their site or
subscribing and sending in questions...
Hope this helps!
http://groups.yahoo.com/group/CDV700CLUB/
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The instruments are made by Victoreen. We have a set here in our training
facility. It comes as a set (CDV 777-1 Radiation Detector Set, "serviced
with pride by Wil Smith, Ed Schock, and Dan Bolinski"). The CDV 700 is a GM
tube count rate meter (0 - .5 mr/hr or 0 - 300 cpm, X1, x10, x100). The
CDV 715 is an ion chamber (0 - 5, x1, x10, x100). I can't find any
literature. Our local towns and city fire departments have them. I've
trained on them a long time ago. They're pretty rugged. I'm checking now
on tech manuals for them. www.victoreen.com has phone numbers you can
contact but the instruments don't appear to be in their catalog. Probably
'50s vintage (meaning they were probably built to withstand a nuclear war).
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The CDV-700 series of radiation survey meters were intended to be used in
the event of a nuclear war. That is something that is only expected to ever
happen once:) Therefore, those instruments were not designed for long term
use. That is, all of the detectors are hard wired, with no BNC connectors.
They were intended to be disposed of after their job was done.
They did have pocket dosimeters, side window GM survey meters and GM pancake
probes. I don't remeber an ion chamber survey meter or an alpha frisker,
but they probably were developed. BTW the State of Ohio has about 10,000 of
them in inventory, that they have been trying to give away, but nobody wants
them.
As far as accuracy goes, they are comparable to other manufacturers
instruments. I believe that they were manufactured by Victoreen under a
federal funded program for civil defense.
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I've done a little bit of work with these meters. They are relatively simple
construction, quite rugged and use very easy to find D-cell batteries for
power. The downside (based on the ones passed on to me over the last few
years):
1) There seems to be significant degradation in the detector tubes in a
large percentage of these instruments. I'm seeing significant tailing in the
high end rate response for the GM-based instruments.
2) Poor maintenance has led to corrosion of battery contacts of many of
these and, in some cases, corrosion of the circuitry.
3) Low energy response is questionable. The design for ruggedness results in
solid metal detector tubes which makes for a considerable reduction in low
energy detection efficiency. I haven't gotten my hands on any response
curves in a while, so I can't recall where the fall-off starts. Just from
viewing the construction, I would guess in the 60-100 keV range, but that's
a real ballpark guess.
I do keep one in the trunk of my car just in case I come across a rolled
over radiographer's truck, but I wouldn't care to use it for much else. I
might be willing to use them for field radiography measurements for gamma
source radiography, but I would want to make some side-by-side comparisons
with commercial ion chambers first.
I don't like the "contamination" meters that I have seen since the ones I've
had my hands on all use side-window, energy-compensated GMs. These detectors
have lousy response for anything but the most energetic betas. And no alpha
response at all.
FEMA issued CPG 2-2, "Use of Civil Defense Radiological Instruments for
Peacetime Radiological Emergencies" in September 1991. This had dose
response curves for the CD V-700 (which indicates to me that the energy
response curve is too non-linear to be used from most applications) and some
information about drift in the calibration. I would view this as a must-read
for anyone considering using these meters.
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The basic kit is the CDV-777-1 which consists of:
1 each CDV-700 side-window GM 0-50 mR/hr gamma, 0-30,000 cpm beta+gamma
1 each CDV-715 ion chamber ~50 mR/hr - 500 R/hr.
6 each CDV-742 direct-reading dosimeters 0-200 R
Other equipment issued:
CDV-700M end-window GM, 0 - 30,000 cpm alpha, beta, gamma
CDV-700RP, a retrofitted spatula-handle frisker probe attached to a standard
CDV-700
CDV-717 windowed-ion chamber 0-500 R/hr gamma window closed, beta+gamma open
window
CDV-720 remote ion chamber (25 foot cable) 0-500 R/hr gamma
CDV-718 dual-GM auto-ranging, digital survey meter/electronic dosimeter
with alarm features
CDV-705 speaker for CDV-700, CDV-700M, and CDV-700RP
CDV-138 DRD 0-200 mR
CDV-730 DRD 0-20 R
CDV-740 DRD 0-100 R
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I have a copy of the DOD publication titled 'Handbook for Radiological
Monitors' that was published in April 1963. The document number is
FG-E-5.9. In the book contains a description of how to operate the CD
V-700 and CD V-715 survey meters. The document also has survey
techniques to use after the big one.
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I have used the CD meters a few times in training and such for rx response
teams. The quality of the meters is fine, just seems that the response time
is a little slower than your typical meter ( ludlum ). The great thing
about them is you can get them for free from a few places!
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They are pretty rugged old GMs, from what I recall. Pretty thick window.
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There are two main models of the CD instruments. The CD V-700 which is
a GM counter and the CD V-715 which is a high range ion chamber. The
REACTS site (www.orau.gov/reacts/gamma.htm) shows the instruments but
doesn't give a lot of detail.
In my opinion, they were a fairly rugged and well designed instruments.
The CD V-700 has a "hotdog" probe GM with a movable beta shield. It
certainly doesn't have the sensitivity of the newer "pancake" probes.
The speaker is a plug-in head phones. One short coming was if you got
in a very high field, the meter would max out and then go to zero giving
a false sense of security, but you could still hear it in the ear phones
if you had them attached.
The CD V-715 is a high range ion chamber and thus not any good for peace
time applications. Most state programs, like the one here in New Jersey
no longer use these instruments because of age and sensitivity, and have
gone over to Ludlum Model 3, 17, etc., for their peace-time nuclear
power emergency response requirements.
While these instruments will eventually become a collectors items, my
experience with them was generally positive.
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Are you referring to the so-called CDV-715? This is the GM meter with the
tube-shaped probe. I've been distributing these to schools, via the Health
Physics Society. They are quite sensitive. I'm sure they could be used
professionally, after calibration. The civil defense ion chamber (CDV-700)
has a scale that starts at 0-500mR/hr. Not very
practical.
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They're fairly solid - durable. They're a little hard to use, sometimes.
Some medical and small academic programs have been authorized to use them
to meet their radiation survey instrument requirements in obtaining a
radioactive material license. They're free.
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