ML19224A999
| ML19224A999 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 06/13/1977 |
| From: | Metropolitan Edison Co |
| To: | Mullinix W NRC/IE |
| References | |
| 1958.3, TM-0200, TM-200, NUDOCS 7906130401 | |
| Download: ML19224A999 (13) | |
Text
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DOCDENT NO:
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0F DOCOSNT PROVIDED BY COPY MADE CN
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METROPOLITA'i EDISON CO'.F/5f.
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Wilda R. Mullinix, NRC 4
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1958,3 R evision 2
B C6/13/77 fiiREE MILE ISLAND NUCLE AR STATION h
STATILN CHEMISTRY PROCEDURE 1958.3 l
GAMMA SPECTRUF ANALYSIS USING THE B&W CRAM PROGRAM Table of Effective Pages Pace Date Revision Pace Date Recision Page Date R evision h
1.0 06/13/77 2
26.0 51.0 2.0 05/06/75 0
27.0 52.0 3.0 05/06/75 0
28.0 53.0 4.0 05/06/75 0
29.0 54.0 5.0 05/06/75 0
30.0 55.0 6.0 05/C6/75 0
31.0 56.0 7.0 05/06/75 0
32.0 57.0 8.0 05/06/75 0
33.0 58.0 9.0 06/13/77 2
34.0 59.0 10.0 05/06/75 0
35.0 60.0 11.0 05/06/75 0
36.0 61.0 12.0 05/06/75 0
37.0 62.0 13.0 38.0 63.0 14.0 39.0 64.0 15.0 40.0 65.0 16.0 41.0 66.0 17.0 42.0 67.0 18.0 43.0 68.0 19.0 44.0 69.0 20.0 45.0 70.0 21.0 46.0 71.0 22.0 47.0 72.0 23.0 48.0 73.0 24.0 49.0 74.0 25.0 50.0 75.0 Unit 1 Staff Recemme
's t pproval Unit 2 Staff Recommend A roval Date Ap proval Da:.
Approva!
Cc;pza.k.A K Cognipn'$[ Hped Un't 1 PORC Recommends Approval Unit 2 PORC Recommends Approval AASw Date 8Y7 '?
h Date S-4-77
[hairman of PORC 7/
Chairman ot'PO RC PCRC ccm ients of included PORC comments of included (date)
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1958.3 Revision 2 06/13/77 ThREE MILE ISLAND NUCLEAR STATION STATION CHEMISTRY PROCEDURE NO. 19Ed.3 GA?'JiA 9ECTRUM ANALYSIS USING THE B & W CRAM PROGRAM 2
1.0 SU.MMARY The CRAM (Computerized Radionuclide Analysis by Mini-Computer) program may be used in lieu of manual integration and computation of the photopeaks of most gamma spectra.
The initial inten; of the program was that it be used for samoles having moderate to high levels of activity where background is of little or no consideration.
The program can, hcwever, be used for lcw level samples provided that backaround is considered.
The analysis, after data transfer, involves three phases.
The first phase is to search each of the 256 channel blocks of data, in order of descending energy, for peaks.
When a peak is located, its energy is determined frcm the latest stored calibration co-efficient and the area is determint a.
This data, along with other preliminary peak data, is both printed out and also stored for use in the second phase of the analysis.
In ;he second phase of the anlysis, the peak energies frcm the first phase are ccmpared with energies from the program's library.
If the energy of any photopeak matches, within 1.3 Kev, the energy of a nuclide defined in the library, a oreliminary identificaticn is mace and a gammas per minute and microcuries per milliliter values are computed using the gamma yields frcm the library and the acprcpriate efficiency curve.
Since the only match required to appear in the listing is that of a single gamma ray, it is cautioned 181 010
19,58.3 M AY 6 1975 Revision 0 that more confirmation is necessary before a nuclide is positively confirmed.
Peaks which were identified in the first phase and still not matched in the second are listed as unidentified peaks and a gammas per mintte at count time value is given.
3 In the third phase, those peaks which have been listed under the j
preliminary identification are examined.
If all peaks for a given nuclide designated with a minus sign in the library are present, that nuclide is confira.ed.
Its activity is then calculated based upon all of the ide-ified peaks weighted according to the gamma yield of the nuclide in question.
Due to the nature of the program, additional care must be exercised when counting samples which have activities a t or near background.
The activities of backgrcund nuclides are com)uted as though all ganmas originated frcm only the sample.
Such data must be compared with background data and discarded after it is confirmed that it really is due to background radiation.
Ccmpensation must also be made in reportad data for the influence of kncwn background peaks whc se gamma energies correspond with those of the reported isotopes.
An attempt should also be made to resolve significant unidentified photopeaks.
2.0 APPARATUS 2.1 HP 5401 MCA 2.2 G; Li Detector 2.3 HP 9320 Miniccmputer with plotter 2.4 B&W CRAM Tape 4
4.0 PROCECURE
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2.0 181 011 e
1958.3 MAY 6 1975 Revision 0 4.1 Energy calibration 4.1.1 This calibration must be performed daily or following adjustments to the equipment which could effect a change in efficiency or energy calibration.
1 4.1.2 Place th) designated Co-60, C5-117 source on the 3 cm j
shelf of the detector, erase the MCA memory and accumulate counts 'ln the entire 4096 channel memory for 20 min.
4.1 -
Place the CRAM cassette in the H.P. 9830 and press " LOAD",
" EXECUTE."
4.1.4 Place the functior. control switch on the MCA in the EXTERNAL position.
4.1.5 Press "RUN", " EXECUTE" on the 9830.
4.1.6 Answer all questions asked by the 9830 by typing in the uns.,er.in the requested format followed by " EXECUTE."
The answer to the type of run desired question should be
" energy calibra tion. "
4.1.7 After the data has ceen transferred from the MCA to the cassette as shown by the heading printout, the program will begin the peak search routine.
Another sample count may now be started on the MCA.
4.i.8 When the peak search is ccmpleted the folicwing data will be printed out:
1.
Slope in Kev /ch.
2.
Offset in Kev 3.
Peak sha'ge data 1
4.
Preliminary peak data
~O 181 012
1958.3 M AY 6 1975 Revision 0 4.1.9 Examine the data described in 4.1.8.
If the slope deviates frcm 0.5 kev /ch by 0.001 Kev or greater or the offset deviates from 0 by 1.0 Kev or greater, notify a superviso-before continuing.
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4.1.10 Plot the peak area counts for the 662 key Cs-137 peak and j
the 1332 key Co-60 peak on the graphs in the MCA calibration log.
If the value falls outside the 2 sigma error bars on these graphs, notify a supervisor before ccntinuing.
4.1.,11 File the calitration printcut in the MCA calibration log.
4.2 Analysis of unknown samples 4.2.1 Count the sample for an appropriate arount of tire using all 4096 channels on the MCA.
A deadtime of less than 10-15% is desirable.
a.2.2 Turn the MCA function switch to the EXTERNAL position.
4.2.3 Place the CRAM tape into the 9830 and press " LOAD,"
" EXECUTE."
4.2.4 When the tape has loaded and the " lazy T" appears, press "RUN," " EXECUTE."
4.2.5 Answer all questions by typing in the answer in the rec,uired format folicwed by " EXECUTE." Answer " normal run" (No. 2) to the type of run desired questicn.
A listing of efficiency files is found in Appendix A.
If the sample is listed in Appendix C use the exact title format shown there.
4.2.6 If "yes" was ans. ered to the plot desired question prepare theplotterbysettingtheloNerleftandupperrightpen positions to align witn the carners of the paper by 4.0 181 013 i
1958.3 WAY 6 1975 Revision 0 pressing " lower lef t" button and adjusting the position controls followed by the " upper right" button and setting its position controls.
4.2.7 After the comolete set of analytical data has been printed out, an interpretation of the data must l e made.
The l
1 steps decribed in 4.2.8 to 4.2.12 inclusive apply.
4.2.8 Compare all peaks in the Preliminary Peak Data section to the latest background printout for the same sample qeometry.
All peaks having count rites w' thin a 2 sigma deviat:on
- 1and should be disregarded by drawing a line through the data.
Lines should also be drawn through those entries under the Preliminary Peak Identification section which correspond to the disregarded ba:kground peaks.
4.2.9 Compare the Preliminary Peak Identification Table to the Final Su= nary of Nuclides Observed.
For those nuclides which are confirmed and have more than one photcpeak examine the agreement of concentrations in the preliminary peak table.
Significant disagreements d;e to interfering peaks (whether background cr other isotopes in the sample) should be resolved.
Cor example, an isetope having 4 photopeaks shows 20% or better agreement in three of the peaks with the 4th peak off by an order of magnitude or more.
The disagreeing peak should be disregarded and a new weighted mean activity should be computed using only the peaks which show agreement,., This new weighted Tean i
shculd be used in lieu of the weighted Tean printed undor the final sumnary.
The weighted mear. should be the sum
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5.0
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19,,58.3 M AY 6 1975 Revision 0 of the products of activity and branching ratio for each photopeak divided by the sem of the branching ratios.
4.2.10 Examine the Preliminary Peak Identification for isotopes having major photopeaks present which show good agreement but which are not confirmed due to absence of one or more h
minor photopeaks.
Compute a weighted mean average and include this value under the Final Summary of "uclides Observed.
4.2.11 Examine the peaks under the Unidentified Peak section.
Compare them with the listings in Appendix B.
Draw a line through all of those which correspond to isotopes already identified.
Also cross out the 511 Kev peak.
4.2.12 Attempt to identify any peaks renc'
'.19 in the Unidentified Peak section.
The Nuclear Data Tables will prove a valuable reference for major gamma energies.
Half-life determinations and known fission or background isotopes will also be of value.
4.3 Generation of Efficiency Curves 4.3.1 Select a standard with gamma photopeaks covering the range of energies for which a calibration is desired.
A mixture of Ba-133 and Eu-154 is suitable for a rance of 80 to 1E00 Kev.
4.3.2 Fabricate a source of the required geometry.
Gravimetric measurements are preferred for dilutions, etc.
4.3.3 Count the scurce in the desired geometry.
The count time i
should be sufficient to accumu! ate 50,3C0 to ICO,CCO ccunts in at least cne peak channel.
Deadtime shculd be i81 015 less than 10%.
6.0 k
MAY 6 1370 1958.3 Revisic i 0 4.3.4 Process according to steps 4.2.2 to 4.2.6 inclusive.
The spectrum should be plotted.
The efficiency table used is not critical since only the Preliminary Peak Da ta section will be used in generating the new curve.
However, a
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table number must be input in order for the program to
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run.
4.3.5 Use only values from the Preliminary Peak Area section.
Select the desired peak energies from the table and divide the corresponding peak areas by the counting tine (min.) to obtain a counts per minute value.
4.3.6 Calculate the gammas per minute which should result frca each source photopeak selected in 4.3.5.
Correct for any cecay.
a.3.7 Divide the counts per minute for each photopeak (from 4.3.5) by the corresponding gammas per ninute (from 4.3.6) to obtain a gamma energy.
Record the gamma energy (in Kev) efficiency (absolute) pair for each peak to be used.
4.3.3 When all pairs of energy vs efficiency have been ccmputed, load the CRAM tape into the 9830 and press " LOAD 21,"
EXECUTE."
4.3.9 When the file has been Icaded, as indicated by the appearance of the " lazy T" on the 9830 display, press "INITh and wait for the " lazy T" to appear again.
4.3.10 Press "RUN 1400" and then " EXECUTE."
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4.3.11 When r ecuested, enter an efficiency table number (see Appendix A) follcwed by " EXECUTE."
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MAY 6 1975 19,58.3 Revision 0 4.3.12 When requested, enter up to 20 energy / efficiency pairs in the format shown on the 9830 display.
Each pair should be follcwed by " EXECUTE." When the last pair has been e,tered, enter a dummy pair (0.0) followed by " EXECUTE."
i 4.3.13 Frepare the plotter when requested and press " CONT",
1
" EXECUTE." The plotter will generate an efficiency curve.
4.3.14 Obtain approval from a supervisor who will initial and date the curve if he approves.
If the curve is not satisfactory, press "ENO, " EXECUTE."
a.3.15 If the curve is approved, press " CONT", " EXECUTE." The program will r! quest a title describing the geometry.
Folicw the tape instructions on the display.
2e sure to allow time for the plotter to form each letter.
a.3.16 File the dated and initialed graph
.id the printcut under the v.CA calibration file.
If the curve is an update of an old curve, mark " superceded by (name & date of new curve)" on the old curve.
8.0 i81 017 i
1958.3 Revisicn 2 06/13/77 APPENDIX A Efficiency.-ile Identificaticn Sample Configuration Geccetry
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On Notch at Jetector 3 CM 10 CM Too of Shelf 10 ml Liquid Vial 31 36 41 2 Inca Planchet 32 37 42 37 mm Crud Disc 33 38 43 6 mi Gas Vial 3a 39 44 Charcoal Cartridge 23 49 50 3.5 1 Marinelli 25 1.0 i Ma rinel l i 25 1.6 1 Gas Ma rinel li 27 Point Scurce so 47 48 25 ml Gas Bulb 45 m
9.0
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1958.3 M AY 6 1975 Revision 0 APPENDIX B Ccomon Unidentified Peaks Photopeak i
l Energy (Kev)
Possible Identification
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352 Ra-226 t
511 Annihilation Peak (Many Possible Isotopes) 583 i
ih-228 l
609 l
Ra-226 620
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I-133 727 I-132 1052 I-133 1260 l
K-40 1530 a
Kr-88 1732 Na-24 f
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181 019 10.0
1958.3 M AY 6 1975 Revision 0 Page 1 of 2 APPENDIX C, Title Formats 1.
Reactor Coolant Samples Press Water Space a
Press Steam Space RC Letdcwn (non degassed sample)
RC Letdown Degassed Liquid RC Let own Gas RC Letdcwn Crud RC-Decay Heat Loop (A or 3) 2.
Samples for Discharge Permits WECST (A cr 3)
'GDT (A or 3)
Laundry Waste Storage Tank 3.
Radiation Monitoring System Samples RM-A (number) Gas RM-A (no) Charcoal RM-A (no) Particulate RM-L (no) 4 Makeup & Purification System Samples Purificaticn Demin. (A or 8) Outlet Makeup Tank Water Space
'iakeup Tank Gas Space 5.
Rad Waste Samples
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M AY S 15,5 1958.3 Revision 0 Page 2 of 2 APPENDIX C (CONT'D) 6.
Backgrounds W
e I.
12.0 181 02I
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