[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

*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



*************************************************************************



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.



*************************************************************************



See the following link and then click on the picture of the meter.

http://www.tdh.state.tx.us/ech/rad/pages/RADINST.HTM



*************************************************************************



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.



*************************************************************************



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/



************************************************************************



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).



*************************************************************************



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.



*************************************************************************



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.



*************************************************************************



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



*************************************************************************



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.



*************************************************************************



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!



*************************************************************************



They are pretty rugged old GMs, from what I recall.  Pretty thick window.



*************************************************************************



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.



*************************************************************************



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.



************************************************************************



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.



************************************************************************

_________________________________________________________________

Get your FREE download of MSN Explorer at http://explorer.msn.com



************************************************************************

You are currently subscribed to the Radsafe mailing list. To unsubscribe,

send an e-mail to Majordomo@list.vanderbilt.edu  Put the text "unsubscribe

radsafe" (no quote marks) in the body of the e-mail, with no subject line.



------------------------------