ML20133P452
| ML20133P452 | |
| Person / Time | |
|---|---|
| Site: | 07001342 |
| Issue date: | 08/19/1985 |
| From: | Klingensmith J BIOCONTROL TECHNOLOGY, INC. (FORMERLY CORATOMIC |
| To: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| Shared Package | |
| ML20133P439 | List: |
| References | |
| 23545, NUDOCS 8511010014 | |
| Download: ML20133P452 (18) | |
Text
0 0
Caratomic, COR ATOMIC, INC.
300 INDIAN SPRINGS ROAD P.O. BOX 434 INDI AN A. PENNSYLVANIA 15701 PHON E:(412) 349-1811 e TELEX 86-6658 August 19, 1985 Ms. Jenny M. Johansen, M.S.
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Nuclear Materials Safety Section B Division of Radiation Safety and Safeguards United States Nuclear Regulatory Commission Region 1 631 Park Avenue King of Prussia, Pennsylvania 19406
Dear Ms. Johansen:
RE: License No. SNii-1319 Docket No. 070-01342 Control No. 23545 We are enclosing two copies of our response to your request for additional in formation.
Sincerely,
- h. Y5}trusw John R. Klingensmith Patient Records Specialist enclosures (2) 8511010014 850925 REQ 1 LIC70 SNM-1319 PDR L
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ma "0ICAICORD COPY"
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- 1..;;3 g iS 1985 ADVANCED TECHNOLOGY SERVING MEDICINE
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License No. SNM-1319-Docket No. 070-01342 Control No. 23545 1.
Regarding your survey meters and counting equipment for alpha and i
neutrons, please submit the following infonmation for each instrument.
a.
Manufacturers Name and Model No.
b.
Number available c.
Sensitivity range d.
Type of detector e.
Type of radiation detected j
f.
Method of calibration or determining counting efficiency Answer:
We have two meters which we use. The first meter is a Scintillation Alpha Counter, Model SAC-4.
It is manufactured by Eberline Instrument Corporation, P. O. Box 2108, Santa Fe, NM 87501. Please see Attachment 1 for answers to Ic to le, and Attachment 2 for answer to lf.
The second meter is a Victoreen Model 488A Geiger Counter.
It is manufactured by Victoreen Instrument Division of VLN,10101 Woodland Avenue, Cleveland, OH 44104. Please see Attachment 3 for the answers to lc to lf.
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License No. SNM-1319 Docket No. 070-01342 i
Control No. 23545 2.
Please submit an outline of the subjects covered in your annual training lecture, the length of time involved for each subject, the name of the instructor, if other than your radiation safety officer (RS0), and the training and experience of the instructor if other than your RSO.
Answer:
I.
All Radioactive flaterial Contained In Sealed Sources (30 minutes)
A.
Fuel Specifications i
B.
Fuel Capsule Specifications C.
Required Markings on Outer Surface of Paceraker II. Radiation Exposure From Pacemakers (30 minutes)
A.
Radiation Exposure to Families of Pacemaker Patients B.
Radiation Exposure to Pacemaker Patients C.
Radiation Exposure to Pacemaker Workers D.
Radiation Exposure in Shipping of Pacemakers III. Radiation Safety Procedures (1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />) f A.
Radiation Detection Instruments B.
Film Badges C.
Leak-Test Procedures D.
Posting and Securing Areas Where Radioactive liaterials are Used or Stored I
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License No. SNM-1319 Docket No. 070-01342 Control No. 23545 3.
Please clarify your recovery / return program. Are the nuclear batteries ever removed from the explanted pacenakers returned to you from the licensed medical institutions and placed in a new pacenaker?
Answer:
When batteries are returned to Coratomic, they may be rn-furbished and the nuclear fuel re-used.
4 i
4.
Please clarify if the inventory /leaktest information given to our inspector during the August 17, 1984, inspection of your facility is the total number of sources you have on hand or does it include the sources which are implanted in patients. We note that this list contained 570 sources.
Answer:
The list is not the total number of sealed sources which we have on hand.
Some of the sealed sources are presently implanted in patients.
5.
Exhibit X for your Model C-100 protocol (July 1, 1975), Exhibit X for your Model C-101 protocol (November 1,1975), and Exhibit IX of your Model C-101-P protocol (March 2,1983),
indicate applications for pacemaker licenses should be sent to the USNRC, Washington, D. C.
Please correct these exhibits to reflect submission of an application to the Regional Office of the NRC which has jurisdiction over the state in which the applicant resides.
It is our understanding that you are only manufacturing and transferring the Model C-101-P pacemaker and protocol, if so, it is only necessa.y to correct the March 2,1983, protocol for the C-101-P pacemaker.
Answer:
Coratomic no longer manufactures the Model C-100 pacemaker or the Model C-101 pacenaker. Explanted Model C-100 and Model C-101 pacemakers are transferred from licensed hospitals to Caratomic. There are a small number of Model C-101 pacemakers, approximately 10, which have never been implanted.
They are occasionally transferred to and from licensed hospitals. We currently manufacture only the Model C-101-P pacemaker. Model C-101-P pacemakers are transferred to and from licensed hospitals.
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n;,c n License No. SNM-1319 Docket No. 070-01342 Control No. 23545 Answer to Question 5 (continued):
We propose the addition of the following cover letter to the protocols for the Model C-101 pacemaker, and the Model C-101-P pacemaker:
"All government hospital license applications should be sent to:
U. S. Nuclear Regulatory Commission Division of Fuel Cycle and Material Safety, NHSS Washington, DC 20555
" Hospitals located in Agreement States should nail their license applications to the appropriate office in that state, instead of to the N. R. C. for approval. The Agreement States are as follows:
1.
Alabama 2.
Arkansas 3.
Arizona 4.
Cali fornia 5.
Colorado 6.
Florida 7.
Georgia 8.
Kansas 9.
- 10. Louisiana
- 11. Ma ryland
- 12. Mississippi
- 13. Nebraska
- 14. Nevada
- 15. New Hampshire
- 16. New York
- 17. North Carolina
- 18. North Dakota
- 19. Oregon
- 20. South Carolina
- 21. Tennessee
- 22. Texas
- 23. Washington
" Hospitals located in Connecticut, Delaware, District of Colurbia, Maine, Massachusetts, New Jersey, Pennsylvania, Rhode Island, or Vermont, send applications to:
U. S. Nuclear Regulatory Commission, Region I Nuclear Material Section B 631 Park Avenue King of Prussia, PA 19406 f
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Page 5
-License No. SNM-1319 Docket No. 070-01342 t
Control No. 23545 Answer to Question 5 (continued):
" Hospitals located in Puerto Rico, Virginia, Virgin Islands, or West Virginia, send applications to:
U. S. Nuclear Regulatory Commission, Region II Material Radiation Protection Section 101 Marietta Street, Suite 2900 Atlanta, GA 30323
" Hospitals located in Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Ohio, or Wisconsin, send applications to:
U. S. Nuclear Regulatory Commission, Region III Materials Licensing Section 799 Roosevelt Road Glen Ellyn, IL 60137
" Hospitals located in Idaho, Montana, New Mexico, Oklahoma, South Dakota, Utah, or Wyoming, send applications to:
U. S. Nuclear f < ilatory Commission, Region IV Material Radiation Protection Section 611 Ryan Plaza Drive, Suite 1000 Arlington, TX 76011
" Hospitals located in Alaska, Hawaii, and U. S. Territories and Possessions in the Pacific, send applications to:
U. S. Nuclear Regulatory Commission, Region V Material Radiation Protection Section 1450 Maria Lane, Suite 210 Walnut Creek, CA 94596"
O.
O Page'6 License No. SNM-1319 Docket No. 070-01342 Control No. 23545 6.
It appears from Attachment 1,
" Fuel Capsule Assembly Procedure",
that you are manufacturing the sealed source that is contained in your pacemakers, please clarify.
i Answer:
This is a material specification used by our suppliers. We do not manufacture sealed sources, but receive them from licensed suppliers.
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SCINTILL ATION ALPHA COUNTER
.g MODEL SAC-4
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COMPLETE ALPHA CO,UNTER SOLID STATE ELECTRONICS TWO-INCH DIAMETER SAMPLE SIZE DETECTOR AND DRAWER ASSEMBLY l
EASILY DECONTAMINATED PRESET TIME:
.1 to 50 MINUTES COUNTERS MAY BE GANGED FOR l
ELECTRONIC TIMER MULTICHANNELS (SPECIAL COVER)
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Attachrnent 1, Page 2 of 6
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.SCINTILLATIO N ALPHA COUNTER l
MODEL SAC-4 I
GENERAL DESCRIPTION The Scintillation Alpha Counter, Model SAC-4. is a complete system consisting of a two-inch detector, high voltage power supply, charge sensitive input amplifier, timer and six decade readout. All circ..ts are solid state, except the detector, with ext.nsive use ofintegrated circuits to enhance reliability.
I SPECIFICATIONS
- 1. DETECTOR
- 5. TIMER: Preset times from 0.1 minute to 50 minutes in a 1,2,5 sequence referenced to line frequency yielding an
- a. Sample Size: 2-1/32" diameter x 3/8" thickness, maxi-accuracy typically better than 0.05%. Long term accuracy is g
mum. The sample thickness can be corrected by an adjust-even better. All integrated circuits are plugged in for ease of 5
able sample holder in the slide.
maintenance.
- b. Scintulation Phosphor: ZnS(Ag) powder on a plastic
- 6. SCALER: Su decade light emitting diode readout. Count-l light pipe.
ing light stays lit when in counting mode. Decade counters 5
and count gate are plugged in for ease of maintenance.
- c. Photomultiplier Tube:
2" diameter,10 stage, Sil response, end window.
- 7. INSTRUMENT RESOLUTION: Appioximately seven microseconds.
=
- d. Efficiency: 80% of 2rr minimum from a 1" diameter as'Pu source.
- 8. RESET-START: Resets scaler and timer to zero and g
starts a timed count.
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- e.
Background:
less than 0.3 counts per minute.
- 9. COUNT MODE
- f. Plateau: At least 200 volts long with a slope of less I
than 1% per 100 volts.
- a. TIMED posit:on automatically stops count after pre-3 set time selected on timer.
- 2. Il!GH VOLTAGE: Regulated, variable by a rear panel control to approximately 1500 volts. The supply (EIC
- b. MANUAL position counts continuously.
l 5
Model P-201 A) is a plug-in module for ease of mainten-ance.
- c. STOP positica does not count.
- 3. AMPLIFIER: Charge sensitive input allowing very high
- 10. POWER: 105-125 VAC,60 liz,1/4 amp,3-wire.
7 input sensitivity with excellent noise rejection, followed by a de coupled amplifier fed back for stability and control.
I1. TEMPERATURE: 32*F to 140*F with less than 150 Overrli sensitivity adjustable by an internal control from volts plateau shift.
E 1.0 to 10.0 volts per picocoulomb (apprc Aimately 0.1 to 1.0 3
- 12. MECHANICAL volt per millivolt equivalent on voltage sensitive input).
a.
Size: 11-1/2"11 x 6"W x 14" D, including controls.
- 4. DISCRIMINATOR: Internally biased at 1.25 volts which gives an overall sensitivity from.125 to 1.25 picocoulombs (approximately 1.25 to 12.5 millivolts), depending on amp.
- b. Weight: 16-3/4 lbs.
lifier gain.
I EBERLINE INSTRUMENT
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CORPORATION l
P. O. Box 2106 SANTA FE, NEW MExtc0 87508 PHONE 505 987 1881 TWX: 9to.985 o679 December 6,1971 TELEX: 660445 E8tRONE AeO r
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SECTION I GENERAL L
A. DESCRIPI!ON sensitivity from.125 to 1.25 picocculombs (approximately 1.25 to 12.5 mdlivolts) depending on amplifier gain.
The Scintillation Alpha Counter, Model SAC 4,is a com-plete system consisting of a two-inch detector, high voltage
- 5. TIMER 4
power supply, charge sensitive input ampbfier, timer, and six decade readout. All c:rcuits are solid state, except the Preset times from 0.1 minute to 50 minutes in a 1,2,5 detector, with extensive use ofintegrated circuits to enhance sequence referenced to 60 IIz line frequency yielding an accu-
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reliability.
racy typically better than 0.05%. Allintegrated circuits are plugged in for ease of maintenance. The timer has an oscil-B. SPECIFICATIONS lator for use with battery or 5011z line. The capability of syncing with a 50 liz line is incorporated in the timer cir-
- 1. DETECTOR cuitry. For this procedure, refer to Section IV, D,3.
- a. Sample Size: 2-1/32" diameter x 3/S" thickness,
- 6. SCALER maximum. The sample thickness can be corrected by an ad-l justable sample holder in the slide.
Six decade light emitting diode readout. Counting hght
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stays lit when in counting mode. Decade counters e..d count g
- b. Scintillation Phosphor: ZnS(Ag) powder on a plastic gate are plugged in for esse of maintenance.
t light pipe.
- 7. INSTRUMENT RESOLUTION: 3.pproximately seve
- c. Phetomultiplier Tube: 2-inch diameter,10 stage, microseconds.
S1i response, end window.
- 8. RESET-START: Resets scaler and timer to zero and
- d. Efficiency: 80% of 2rr minimum from a 1 inch starts a timed count.
diameter Pu22' source.
- 9. COUNT MODE
- c.
Background:
Less than 0.3 counts per mmute.
- a. TIMED position automatically stops e ant after
- f. Plateau: At least 200V long with a slope of less preset time selected on timer.
thaa 1% per 100 vc *s.
- 2. HIGH VOLTAG.
Regulated, variable by a rear p nel control to approxi-mately 1500 volts. The supply (EIC Model P-201 A) is a
- 10. POWER: Line -115 cr 230110% VAC switch scleet-plug-in module for ease of main:enance.
able,50/60112,1/4 amp,3-wire. Battery - Any battery 7.5 volts mimmum,14 volts maximum at 1.0 amp load.
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- 3. AMPLIFIER
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l1. TEMPERATURE: 32*F to 140*F with less than 50V Charge sensitive input allowing very high input sensitivity plateau sluft.
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with excellent noise rejection, followed b'y a de coupled amp-lifier Ted back for stability and control. Overall sensitivity
- 12. MECilANICAL adjustable by an internal control from 1.0 to 10.0 volts per
_a picocoulomb.(approximately 0.1.to 1.0 volt per milhvolt
- a. Size: 11-1/2"11 x 6"W x 14"D, including controls equivalent on voltage sensitive input).
- b. Weight: 16-3/4 lbs.
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- 4. DISCRIMINATOR
.,.J Internally biased at 1.25 volts, which gives an overall l
I CitANGE 1
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Attachrent 1,,Page 4 of 6fC' o
- ,c: u.o SECTION !!
OPERATION A. DESCRIPTION OF CONTROLS
- 4. Set COUNT TIME IN MINUTES switches to I and 8
X. I.
- 1. EXTERNAL (See Figures 1-1 and 2-1)
- 5. Push RESET-START switch. Instrument should stop
- a. COUNT MODE: Switch to scleet timed count counting after 6 seconds.
I (TIM ED), no count (STOP), or continuous count (M AN UA L).
- 6. Check efficiency and background. Refer to Section
- b. RESET-START: Switch to reset all appropriate IV, D,2,e and f.
circuitry to zero and start a timed counting sequence.
E D. OPERATING TIIE INSTRUMENT
- c. COUNT TIME IN MINUTES: Switches to select desired counting time.
- 1. Set MODE switch to TIMED.
- d. POWER (Rear Panel): Switch to supply power to
- 2. Determine a count time and set COUNT TIME IN the instrument.
MINUTES accordmgly.
e.11. V. ADJUST (Rear Panel): Control for adjusting
- 3. Pull the sample drawer until it 4 fully cxtended and to proper high voltage.
place the sample to be counted on the adjustable sample holder.
I I 50/60 112.
- f. Il5 230 VAC Switch: Selects either ll5V or 230V The sample holder snap ring : ay be used to hold a flex-ible 2-inch diameter sample flat.
- 2. INTERNAL (See Figure 2-2)
For maximum efficiency, rotate the sample holder until I
- a. GAIN (Amplifier Board): Control for adjusting the surface of the sample is as high as possible, but make gain of amphfier.
sure that no part of the sample extends beyond the surface of the slide.
j
- b. TIME BASE (Timer Board): Control for adjusting 3
time base of timer when instrument is used with a battery.
- 4. Push samp' drawer fully closed.
1 (This is not a normal mode of operation for a SAC-4,so no L_
adjustment of this controlis necessary when operating from
- 5. Push RESET-START switch.
an AC line.)
- 6. Instrument will stop counting after the preset time B. PREPARATION FOR USE and the scaler will display the total counts for that time.
- 1. The instrument should be checked for physical damage.
E. PRACTIC AL CONSIDERATIONS OF COUNTING r
RANDOM EVENTS (RADIOACTIVITY) 1
- 2. Plug cord into 115 VAC,60 !!z power source.
- t. STATISTICAL DEVIATION
- 3. Turn POWER switch ON and push RESET-START.
When the total number of counts recorded from a radio-active source is small, the number can be considerably differ.
E C. OPERATION CllECK ent from the average source value due to statisticaldeviation.
- 1. Place an alpha source in the instrument.
The radiations from a source are random in nature and s
the b,s of probability apply. From a determined number
- 2. Set MODE switch to MANUAL. Instrument should ofcc s, the following equations can be used to calculate begin counting. Count lamp should light.
the(
ion to be expected from the average source value.
- 3. Set MODE switch to TIMED.
ard deviation (S.D.) is defined as the square root
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of 1ge total nuinber of counts (NA). The symbol 9
r CilANGEI 3
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for this is e. Thus,
- 3. ERROR IN CON 1BINING TWO DETERhlINATIONS S.D. = c =lNA Eq. I If the background count is comparable to the sample count, considerable error can be had in the solution when Any determination (N) on a sample will be within a cer-the background is subtracted out. The following formula tain deviation of the average a fixed percent of the time,as applies:
listed below.
-+-
95% confidence level S
B N = NA t.674 e 50% of the time Eq.11 N=NA!c 68% of the time Eq.111 R = Net count rate of sample in counts per minute, N = NA 2e 95% of the time Eq.IV N = NA 3e 99.7% of the time Eq.V Rs = Count rate of sample and background in counts per minute.
Example A: A 2500 CPM source is counted 100 times for 1 minute each.
RB = Count rate of background in counts per minute, From Eq. I, S.D. = e =h500 = 50 CPM Ts = Time that sample and background were counted in minutes.
The distribution of the individual counts will be as follows:
TB = Time that background was counted in minutes.
From Eq.11, 50 counts will be within 2500 34, or Example C: Background count is 20 counts in 10 min.
2466 to 2534 CPM.
utes, and sample plus background count is 100 counts in 10 minutes. So, From Eq.111,68 counts will be within 2500 50,or 2450 to 2550 CPM.
Rs = 100/10 = 10 CPM RB = 20/10 = 2 CPM From Eq. IV,95 counts will be within 25001100, or Ts = 10 minutes 2400 to 2600 CPM.
TB = 10 minutes 7t From Eq. V, ne.arly all counts will be within 2500 R = 10 2 2d +,~ = 8 22 9 = 8 22.2 CPM (8 27%%)
Q 10 10 1150, or 2350 to 2650 CPM.
at 95% confidence level.
There is always the possibility that a count will be far g
away from the aserage, but this will happen only a small To get the highest accuracy in the minimum amount of W
percentage of the time.
time, the sample counting time (T ) and background count-S ing time (Tgp should be distributed accordig to the followmg
- 2. COSFIDENCE LEVEL formula:
When the average count from a sample is not known rad Ts j Rs the accuracy of one determination must be specified, e con-
{B RB fidence lev's must Se used. Confidence level correst.;nds to the percentages in Eq ations il through V. At 50% con-
- 4. RESOLVING TIME ERROR fidence level, any one ( ttermination will be within 1.674o-of the average count. Ai the 95% confidence level, any one When counting samples with a high count rate, the de-3 determination will be w :nn 27 of the average count.
termination can be in error because of the fmite resolvir.g 5p l
I time of the counting system. The resolving time of a counter Example B: A one minute determination on a sample can be determined by counting two sources of approximately i
I reads 1747 counts. The standard deviation (a- ) is 42.
the same value individually and then together and applying The accuracy of the determination can be specified as the following formula:
I follows:
R+R-R2 1
2 1
1747228 CPM SO%confidencelevelor 1747 84 CPM
,y.
95% conficance level.
2(R R )
1 2 The 95% conf;dence level is in fairly corumon tasage, how-where:
ever any level can be used as long as it is specified.
<r= Resolving time (seconds) l 4
ORIGINAL I
{L Attachment J.,Page 6 of 6 p j k '_. [,
t MODEL5AC4 R1 = Counting rate, source 1 (counts per second) where:
' R2 = Counting rate, source 2 (counts per second)
R = True counting rate (counts per second)
R12 = Counting rate, source 1 + 2 (counts per second)
Ro = Observed counting rate (counts per second)
T= ResoMng time (second)
When the resolving time is known, an observed count can be corrected by applying the following formula:
Due to simplification of the above equations, the accu-racy of the correction is limited if the correction exceeds g
about 20%
R = l - Roy 1
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- 8193 QniibrationofAlphaCounter O
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i Eberline Scintillation Alpha Counter Model SAC-4 lf i
i 1.
Assure that the sample table is positioned tightly against the snap ring and the copper retaining ring.
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2.
Place the Pu standard source in the certer of the sample table.
Push the sample drawer fully closed.
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3.
Set COUNT MODE to TIMED, and the COUNT TIME in MINUTES switches to 1 and X10 to obtain a ten minute timed count.
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l 4.
Push the START-RESET button; the counter will begin counting.
5 5.
When the count lamp goes out, divide the final count by 10 to get the average counts per minute (cpm).
If this value lies in the Average cpm Range on the calibration sticker, record the efficiency of the counter as that which is i
listed on the calibration sticker.
Set the counter's COUNT TIME in MINUTES switches to 1 and X1 before doing the wipe tests in order to obtain one minute timed counts.
1 j
6.
If the average counts per minute is outside the Average cpm Range on the j
calibration sticker, repeat steps 1 thru 5 above.
If the second ten minute j
timed count does not yield an average cpm in the calibration range, a new determination of the counter's efficiency must be made.
l Determination of Alpha Counter Efficiency
>0 1.
Do steps 1 and 2 above.
k 2.
Set COUNT MODE to TIMFD, and the COUNT TIME In MINUTES switches to 1 and XI.
l 3.
push the START-RESET button; the counter will begin counting.
4.
When the count lamp goes out, record the displayed count.
l
'5.
Repeat steps 3 and 4 to obtain 50 one minute counts.
6.
Divide the sum of all 50 counts by 50 to obtain the average total counts (NA).
Take the square root of this value (NA) to obtain the standard deviation (r).
l Thus:
I 50 ounts- =
NA (NA)
=
e-7.
The laws of probability state that any random determination (N) of the sample
.will be within.the range, NA t 2r, 95%.of the time.
l Thus:
N i NA i 2a-957. of the time whereNAt2d._is_arangeofvalues.from(NA-2c)to(NA+2r),
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Prga 2 Example-9 Fifty one minute counts of a Pu source were taken.
The average total
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counts per minute was 937.
(NA)U = (937)' = r = 31 E 50 ounts
= NA = 937 For an average value of counts per minute of 937, there is a standard deviation of 31.
Therefore: Any count will be in the range 937 1 2(31) 95% of the time.
ie.,
N = 875 to 999 95% of the time Thus the 95% confidence range in this case is 875 to 999. We can be 955 certain that any random determination of the sample will fall in this range.
8.
Take the minimum value in the 95., confidence range and divide it by twice the certified cpm of the Pu239 source to obtain the minimum efficiency of the counter.
9.
Take the maximum value in the 95% confidence range and divide it by twice the certified cpm of the Pu239 source to obtain the maximum efficiency of the counter.
- 10. Therefore, the EFFICIENCY RA'lGE of the alpha counter has been determined with 95% confidence.
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Example:
Continuing with the same xample, the minimum value in the 95% confidence range is 875, and the maximum value is 999.
239 The Pu standard source in this case has a certified 1380 cpm.
Thus the minimum efficiency is:
875
- 32 = 32"
=
2(1380) 999 The maximum efficiency is:
2(1380T=*36=36#
The efficiency range in this case is 32% to 36%, or 34% i 2%, with 95%
confidence. This efficiency has been determined in terms of disintegrations per minute (dpm).. The actual count divided by the counter's efficiency yields actual dpm values.
One microcurie is equal to 2.2 X 106 dpm. 'Thus, 6 yields microcuries.
the actual dpm divided by 2.2 X 10 Example: The alpha counter's efficiency = 34% t 2%
The final count of a determin'ation = Scpm
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pm. = 14.71 dpm Ihh=6.7X10-6 5
microcuries
achment 3. Page 1, of'3
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- 3. Unscr;w thmb13 connector c.t the probe.
3-6. DETECTOR PRODE.
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and tha handle frsfhe cord.
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- 5. ecrz. the cabk
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tniction.
His neutron sensitive probe consists of:
- 1. A boron-lined proportionalcounting gas-C.
Sensitivity.
filled tube. Typa RSN 127A, which when operated at The sensitivity of the detector tube alene, to 900 volts puts out a pulse frota the B10 (n, alpha) re-thermal neutrons when read on the 406A survey metcr.
action which is large enough to permit locating the pre-is 12,120,1200 or 120,000 thermal neutrons per em-ampin the survey meter case rather than in the probe, per second(av thermal)which corresponds to approxi-
%c preamp and counting circuit sensitivity is such that mately.045,.45, 4.5 or 45 mrcm per hour.
gamma pulses are effectively discriminated against.
The boronlining gives a 1/v senaltivitytothermaland D.
Area *.:rveys.
slow neutrons.
Tno thermal neutron detcetor la of prime interest 2.
A high-density polyethylene modcrator to the health physicist because therinal and slow neu-which extends the detectable neutron energy range into trons have a much higher interaction cross-section tohuman tissue than dointermediate and fast neutrons.
the fast neutron region.
3.
A 1/32" thick cadmium shield whichper-Further, it is much more probable that an intumedi-mits discrimination a;;ainst thermal neutrons.
ate ot fast neutron will be thermalized by human tissues before it is captured. Therefore, the ideal survey in-B.
Operation.
strument would ba a thermal neutron d2tector sur-The detector tube, raoderator, and cadmium rounded by a mod 2rator which will thermalize the shield maybefastened to cach otherand to theinstru-neutront present in the same rnanner as the human ment case in any combination with the pach-button body does. Since it.c dose rate is non-uniform thror~'
fasteners on the detcetortuba flange and the cadmium out the body volume, and since the ideal moderatm may.be quite large, the moderator supplied with the shield Dan;e.
48EA Survey Meter necessarily represents a com-The detector tube flange may be removed to permit promisc between the ultimate in accurccy, size, port-incertion of the whole detector tube into a or.e inch y an Wn nC possMy of udng Re cavity, if r.ecescary. After turning the instnament off, cadmium shield, moderator, and probe in differer.t the procedure for removing the flange is as follows:
combinations also affords a convenient opportunity for
- 1. Grasp the prob collar with a wrench.
determining the approximate neutron spectrum pres-
[
- 2. Unscrew the handle by turning counter-ent. Tbc 4SSA Sarvey Meter and 4SS-22 Ncutron Proba clockwise. Slide the handic down the cord, will completely discriminate against gamma ficids.
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Attachment of the Carrying Strap.
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Circuit Board Assembly.
SECTION IV MAINTENANCE 4 -1.
REPLACING TIIE BA'ITERIES.
c.
Turn the Model 48SA to the X10 range and ad-just Ge"CAVpotendometeron tWA ckcun boad Battery replacement is accomplished as outlined in the unut h meter scale reaW b &nucal we & W Section 3-1. The end potnt of the cells is 1 (one) volt repetition rate of the pulse generator.
per cell. By far the bestpreventive maintenance pro-cedure that can be recommended la to make certain 4-3. Cl!ECKING THE }{IGli VOLTAGE POWER SUP-that the instrument is turnedoff at all times when not p Ly.
In use. Life of the batteries is about 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> under When de power supply is operating, a buzz of about continuous operation, and 175 hours0.00203 days <br />0.0486 hours <br />2.893519e-4 weeks <br />6.65875e-5 months <br /> when operated 100 cps in frequency can be heard due to the oscil-four hours a day.
lations of the power transformer laminations, if this 4-2.
CALIBRATION.
buzz is not audible, the oscillator section is probably n t operating and the setting of R9A should be checked.
The Model 489A Survey Meter can be calibrated in is screwdriver adjustment is set properly by the counts per ininute by applying,the output of a, pulse generator to the inpul and adjusting the "C A L" adjusting 1 11 wing precedure.
potentiometer. A pulse D'nerator producing negative 1.
Insert a 0-100 ma meter in series with the power pulses at least.05 volts amplitude, approximately supply batteries, BT1 and BT2.
5 microseconds in durs*
and approdmately 6000 2.
Arn the " liv" adjustment fully counter-clock-pulses per minute in rep in rate. Calibration is
- wise, accomplished in the fol!c manner:
3.
Arn the instrument "ON".
4.
Advance the screwdriveradjustment clockwisc from the Model 48S A.
n.
Remove the case,
? pulse generator, in until the meter reads 33 ma with the new batteries.
b.
Connect the outp series with a 500puid, capacitor to the in-ne high voltage output of the power supplyshould bc put connector on the Mo(
case top.
tested with an electrostatic voltmeter. De volt 3Re
.