ML19290B934
| ML19290B934 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 12/31/1978 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML17174B224 | List:
|
| References | |
| FOIA-79-488 NUDOCS 7912140513 | |
| Download: ML19290B934 (23) | |
Text
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ENVIRONMENTAL DOSE PATWAY STUDY ZION STATION Spring 1977 through Fall 1978 4
5 N
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1578 530 DECDGER 1978 T F-79 l Al4o 5 /3
O
'"DEX PAGE Introduction to Zion Program...........................................
1 Car.una Do s e f rom Airbo rn e Ef flu e n t s....................................
1 Radiation Dose Using Thermoluminescent Dosimeters.....................
2 Pressurizad Ion Chamber Program.......................................
4 I-131 Air to Milk Pathway Study.......................................
5 Aq u a t i c Pa t hwa y S t u d y.................................................
6 References............................................................
9 Dr e s d e n P r o g ram S ta tu s S un:ma ry........................................ 15 Quad Cities Program Status Summary.................................... 22 O
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1578 531
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ENVIRONMENTAL DOSE PATHWAY STUDIES AT ZION STATION Summer 1977 through Spring 1978 Introduction The more complete the knowledge of source terms and pathways of radioactive effluents, the greater can be the confidence placed in popu-lation dose values. This knowledge is expressed in calculational models first based on, and then confirmed by source-term and pathway measurements.
Environmental monitoring should initially contribute pathway transfer co-efficients, and later be available for measuring any unforeseen releases, and confirming exposures from normal releases.
Much remairs to be done in developing and confirming calculational dose models, either generic or station-specific. The operating and waste-treatment systems at nuclear power stations are still evolving, complex and not easily monitored; and the factors that affect transfers differ greatly from place to place. The recent consolidation of calculational models for Appendix I considerations was an ef fective utilization of data from station operation and special studies, including the numerous studies undertaken at Commonwealth f acilities. Environmental measurements at power stations have been less productive because only a few special studies provide numerical results, as contrasted to the usual "less-than" values from routine monitoring programs. Moreover, most pathway calculations are based on indirect information, derived from studies of effluents at ERDA laboratories and of fallout from nuclear tests.
Studies conducted at the Zion Station from nid-1977 through early 1978 were designed to provide information on the levels of radioactivity in the station environs, to estimate potential doses from station releases, and to correlate measured dose rates and concentrations with those predicted by mathematical models. The three pathways chosen were: airborne cloud gamma radiation, iodine-131 in milk, and aquatic. Based on previous studies at Zion and elsewhere, the first,two pathways were considered to be the most significant pathways for off-site population dose due to station releases.
Analytical, survey, and sample procedures were written and equipment
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was developed and constructed for various needs in the program. Results of studies of each of the three pathways are given below.
1:0 Measurement of Gacma Radiation Dose from Airborne Effluents The objective of this part of the study was to determine the radiation dose due to airborne effluents from the station.,
i578 532 e m.mn-
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The approach was threefold. Packets of lithium fluoride (T1 activated) thermoluminescent dosimeters (TLDs) were emplaced at 12 locations in each available sector (the plant is bordered immediately on the East by Lake Michigan) for measuring the integral dose at roughly the site boundaries.
Camma surveys were to be taken biweekly at each of the TLD sites to provide instantaneous readings of gamma count rate at each site, and indirectly, dose rates by comparing the gamma count rates with dose rates measured simultaneously by means of pressurized ion chambers (PIC's). Pressurized ion chambers were to be installed at two fixed locations approximately 1800 apart. Digital output was to be recorded on magnetic tape for computer processing to list, categorize, and compare dose rates at the two locations.
Late delivery of the ion chambers and malfunction of the equipment when it did arrive prevented performing the ion chamber study. Data pro-cessing programs were, however, written and tested and are discussed below.
The gamma survey program was likewise ineffective due to equipment problems, severe weather in the area, and lack of ion chanbers to relate the gamma count rates to the dose rates. The TLD program and the fruitful aspects of the PIC program are discussed below.
1.1 Measurement of Radiation Dose using Thermoluminescent Dosimeters (TLDs)
TLDs were emplaced in each of 12 available sectors around the plant at approximately the site boundaries. Details of distances and directions of the installations are given in Figure A and Table A as are measured dose rates for the locations. Each TLD badge consisted of 5 individual dosimeters of Harshaw TLD-100 LiF (TI),1/8"xl/8"x.04", housed in a plastic Polyvinyl-chloride and Polyethylene holder having a total thickness of 56 mg/cm. All 2
TLDs used in the program were selected to provide response within tS% of the mean response for the dosimeters used in the program.
The dosimeters were read on an Eberline Instrument Corporation model TLR-5 reader set up to provide a sensitivity of about 18 counts per mR with a background of about 2 counts. Error terms quoted in Table A are based on the standard deviation of the average readings for the five chips in each badge.
1.1.1 Findings 1.
In six out of the eight cases where comparisons could be made, second period readtugs were blightly higher than those for the first period. The maximum difference was 2.1 mR/ Quarter (0.96 pR/hr.) at station "B", North of the plant and the average difference was 1.2 mR/Q (0.55 pR/hr.). Both of these differences neglect the statistical uncertainties. One station, "K", S-SSE which was higher during the first period was probably affected by radiography which was conducted in the area. Station "L" was obviously affected by this radiography
. 1C7 R77 lJl JJd
O TABLE A Camma Background by TLD Average UR/hr (a)
Site Sector Direction Distance (m)
Aug - Nov 1977 Dec - Mar 1978 A
NNE 240 305 LOST 5.410.3 B
N 1.5 427 5.710.0 6.710.3 C
NNW 328 640 LOST 6.4!0.3 D
NW 312 518 5.410.1 6.310.3 E
WNW 298 427 5.610.2 5.810.4 F
W 270 350 5.610.2 6.010.2 C
WSW 246 305 5.410.2 5.9!0.5 11 SW 228 373 5.510.3 5.210.3 I
SSW 213 381 LOST 5.510.3 J
SxsSW 191 411 5.410.2 5.Si0.3 K
SxSSE 172 396 6.810.2 5.5!0.3 L
SSE 156 335 (b) 95 !2 5.610.3 (a) With transportation control average of 0.6mR per round trip subtracted.
N (b) Exposure due to radiography in the area. Possib7e effect at Site K as well?
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2.
During the second period stations in the West to North quadrant (270 -
24' have (disregarding statistics) a slightly higher average dose rate than do those in the South to West (156*-2560): W-N 6.09 pR/hr., S-W = 5.59 pR/hr.
e 3.
TLDs from the West and South locations for this program are located close to the installations for the standard program. Exposure rates are about the same for 'oth the EDPS and standard programs.
o 1.1.2 Summary of TLD Program The program demonstrated that fairly small differences in dose rates for different locations can be measured using TLDs. With the exception of one station and possibly a second which were known to have been exposed to an extraneous source, all other readings were within the ranges to be expected.
Because of the unavailability of PIC data, comparisons of dose rates between the two systems could not be made. This comparison is the core of the program since the PIC measurements are assumed to represent " background" values to be subtracted from the TLD readings to obtain the station contribution at each location.
1.1.3 Comments on the Program A significant problem encountered in the prc3 ram was the loss of dosi-meters. We believe the losses were mainly due to vandalisn since no dosimeter.1.
were lost during the second period when access to the sites was severely restricted by unusually heavy snows. The sites chosen for TLD stations and gamma surveys will necessarily represent a compromise between ideal location as regards distance and sector, and practical aspects of accessibility and security.
Dosimeter holders might well be modified to represent depth dose rather than some intermediate value since depth dose is of greater significance than surface or skin dose. Tissue equivalent or depth dose equivalent dosimeter holders are available and will be tested in future prograns.
1.2 Pressurized Ion Chamber Program As mentioned in Section 1.0, satisfactorily working equipment was not received from,the manufacturer in time to be used in the project. Programs were developed to summarize, list, and make comparisons of the output of the ion chambers.
Digital data from the tape cassettes are read into the computer. The cocputer calculates uR/hr. for each data point and then calculates the mean and standard deviation of all the readings for each one* hour (approx) period.
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Pre-established standard deviations tell the computer what to do with the data. If the standard deviation is below come value X, the one hour average is attributed to natural background. If it is above X, then the last "back-ground" reading before that one hour period and the next one following that one hour period are averaged to assign a background value to that period.
The difference between the assigned background and the total dose reading is attributed to plume radiation. Thus the total dose (background plus plumei, background dose, and dose attributed to the plume will be calculated for the two locations.
PIC data are tabulated as follows:
Hour of Average Standard Deviation Date Day urad/hr urad/hr At the end of each period, the total uR (background plus plume), background uR, and plume pR will be calculated for each location. Background for the other TLD locations will be calculated using survey meter (SM) readings. The following ratio of the SM reading (when the plume is not present):
SM (PIC. Station) multiplied by the computed background at the PIC station gives the background for each TLD location. The difference between this calculated background and the total dose measured with the TLD is then attributed to the plume at that location.
Additional information on background dose is expected to be made available by comparing simultaneous data from the two PICS. When neither is affected by the plume, both may be expected to respond simultaneously to changes in the environmental background due to radon release and/or entrapment, fallout from nuclear tests, cosmic ray effects, etc., and thus gain a more accurate measure-ment of the "true background dose rate". This information is important to the study since the values for background must be subtracted from the values measured using TLDs.
Data processing runs made with " synthetic" data performed well, but modifications to the programs will undnubtedly be found desirable once actual data are available for use.
N 2.0 I-131 Air to Milk Pathway Study The purpose of this program was to measure the levels of I-131 in milk from farms near the station and to relate the concentrations measured to those predicted by mathe=atical models. The program ran satisfactorily from 15 June 1977, through 30 October 1977, providing weekly data until intrusion of radio-active iodine from an atmospheric nuclear test in the People's Republic of China in late September of 1977 was detected.
1578 536 _.
2.1 Procedures Samples of about 1.5 liters of milk were obtained from the morning and evening milkings of two farms and frozen until the weekly collection was made.
Prior to processing, the. stable iodide concentrations of the samples were measured using a specific ion electrode. Initially, both direct and standard addition methods were used to measure the iodide until confidence was gained that the direct method provided satisfactory results.
Concentrations of stable iodide in milk have been shown in this and other studies to be quite variable and often quite high, making knowledge of the total iodide present, not only carrier, important to recovery deter-minations. Other than the iodide measurement step, the samples were processed according to standard procedures which were slight modifications of those outlined in former Regulatory Guide 4.3 consisting of extraction of the iodide on an anion exchange resin and precipitation as AgI after purification by classical methods. The samples were counted in low-level beta detectors for periods of about 1000 minutes and the measured I-131 concentrations corrected for decay to the mid-time of sample collection.
2.2 Discussion Analytical data for the iodine ueasurements are found in Table B.
Algebraic means for samples prior to incurcion of Chinese debris were:
Ames - 6 mi NW = 0.000 pC1/1 Steinbrink - 15 mi NW = 40.019 pCi/1 The esgnitude of the positive bias at Steinbrink is due mainly to one sample (06/25/77). If this number is ignored, the averages in both cases approach zeco, indicating little if any bias in the analyses. Average weekly iodine release data were obtained from the station radiatioa pro-tection chemistry group and then using calculational methods found in NRC Regulatory Guides 1.109 (1) and 1.111 (2) the I-131 concentrations were predicted. The predicted values were then compared to actual concentrations.
The data shown in Table C for the two Zion Dairies indicate that the calculational models cannot be validated even with the sensitive measure-ments that were employed. More study of this pathway such as the inter-agency studies performed by the NRC and the U. S. Environnental Protection Agency are zecommended.
(3, 4, 5) 3.0 Aquatic Pathway Study These aspects of the aquatic dose pathway were to be studied: photon emitters in fish, photon emitters in public water sanples, and predicted vs.
measured concentration of tritium in public water samples. Fish samples were not available in sufficient quantity to permit measurements at the sensitivities required for the study, hcwever, procedures were developed and tested for mear.urement of phosphorus-32 in edible portions of fish.
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g 3.1 Measurement of Photon Emitting Nuclides in Public Water The objective of this study was to measure at high sensitivity, the concentration of radioactive naterial in water from Lake County Public Water District (LCPW) plant intake which is located about one mile north of the Zion Station. A compositer was installed on the LC PWD plant intake which operated whenever the LC PWD plant pumps were operating. The compositing system was designed to collect a sample of about 100 liters during any selected time of from two hours to one week. Composite samples were to be measured at varying periods after an effluent release by the Zion station, and the measured concentrations compared with values predicted by models.
Procedures were developed, equipment tested, and background measure-ments made on large (-100 liters) volume water samples from the collection point. The extraction system (Fig. B) consisted of cation and anion exchange resin beds in series following a particulate filter. The samples were pumped through the system using a peristaltic pump at a flow rate of -100 ml per minute. Tracer experiments with spiked lake water samples indicated that recovery of the significant radionuclides was essentially 100% except for cesium for which the recovery averaged about 94%. No tracers were detected in the second column. The anion column was essentially 100% efficient for collection of iodine (as iodide). Traces of activity (<1% of the total) were measured on the particulate filter.
The contents of each resin bed and the particulates were counted separately for 1000 minutes each on a gamma spectrometer (GeLi). Results of background determinations on two samples from the Lake County intake are given below.
Sample Date:
07/12/78 11/08/77 Nuclide pCi/l pCi/l Ce-144
<0.2
<0.15 1-131
<0.04
<0.03 Ba-La-140
<0.1
<0.08 Cs-134
<0.04
<0.03 Cs-137 0.035!0.010 0.04!0.01
,Zr-Nb-95
<0.06
<0.05 To-58
<0.03
<0.03 Mn-54
<0.03
<0.03 Zn-65
<0.07 (0.06 Co-60
<0.04
<0.03 The origin of the Cs-137 is undoubtedly due to world' wide fallout.
Releases from the station were too few and too small to permit the antici-pated concentration comparisons to be made.
1578 538 _ _ _. _
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3.2 Tritium Concentration in Public Water Supplies Tritium concentrations at six different lake sampling locations were measured. Five lake sampling locations provide ambient tritium concentration in the lake and the sample collected at a nearby public water intake provided the tritium concentration (C=Ca + ACo).
The expected tritium concentration at the public water intake was calcu-lated in the following manner. First the concentration in the Zion Station discharge was computed from records of station tritium releases (C, pCi/1).
o Then the initial tritium concentration in Lake Michigan near the discharge structure was estimated from environmental measurements of water temperature, assuming no heat loss to the atmosphere.
This dilution called the entrainment factor, dilutes C, to approxi-mately C /10. Next, using a mathematical model described in the Ziou Final o
Safety Analysis Report the dilution during plume transit from the point of discharge to the point of intake was determined. This provides an upper estimate of A C of Co/30. A lower estimate of A Co is found by including o
a factor to accomodate the shif t in the direction of lake current, which near Zion Station flows north approximately 60 percent of the time on an annual basis; 40 percent to the south. Thus, on the average, the concentration at the public water intake should be C /60.
o The data shown in Table D indicate that the dilution model presently used at Zion is adequate for it does not underestimate the incremental of tritium.
Bs 1573 539
o O
REFERENCES 1.
U. S. NRC Regulatory Guide 1.109 " Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR50, Appendix I",
Mar. 1976.
2.
U. S. NRC Regulatory Guide 1.111 " Methods for Estimating Atmospheric Transport and Dispersion of Gaseous Effluents in Routine Releases from Light-Water-Colled Reactors", Revision 1, July 1977 3.
B. H. Weiss, P. G. Voilleque, J. H. Keller, B. Kahn, H. L.
Krieger, A. Martin, C. R. Phillips " Detailed Measurements of I-131 in Air, Vegetation and Milk Around three Operating Reactor Sites", IAEA-SM-180/44, pp. 169-190, 1974.
4.
B. H. Weiss, P. G. Voilleque, J. H. Keller, B. Kahn. H. L. Krieger, A. Martin, C. R. Phillips, " Detailed Measurements of I-131 in Air, Vegetation and liilk Around three Operating Reactor Sites",
NUREG-75/021, Mar. 1975.
5.
H. L. Krieger, D. Montgomery, B. Kahn, B. H. Weiss, P. G. Voilleque, J. H. Keller, " Evaluation of the Air-Grass-Milk Pathway for I-131 dated 1976, to be published as NUREG report.
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O D
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MICHIGAN G
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I N
I
-l Figure A - Location of TLD - Camma Survey Stations Zion EDPS Program 1977 7 g
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a Figure B ZION EDPS r
Radionuclide Extraction System - Lake Mater To Drain
=
m u
y a
a L
a
=
8 8
8 i
E g-i E
i i
u u
u Y
O O
(VariableFlowPump Glass Vool Prefilter i
To Sampic P.eservo.ir l
lon Exchange Column Specifications ID =
5 cm
-H
= 30 cm Connecting tubing: Tygon Bed Volume = 500 cc 1578 542 TABLE B I
to I-131 IN HILK SAMPLES - ZION EDPS PROGRAM 1977 Steinbrink Farm (15 mi._NU)
Ames,_ Farm (6 mi. WNW)
.loction Vol(1)
I-12L Grav.
Total likg.
I-131 Vol(1) 1-128 Oray.
Total 13kr,.
I-L31 Ld Date e-At Proc mg/l Yic1d epm cpm pCi/1 1 la Proc mg/l Yield epm epm pCi/1 ! lo i/18/77
.74 17.0 0.28
.82r 1.872.04 1.87 0.0002.007 18.0 0.60
.46 1.68.04 1.70
.0041.012 i/2 7
.68 17.0 0.53
.51 1.59!.04 1.58
+0.0011.012 17.0 0.28
.49 2.05!.04 1.45
+.1192.012 7/02/77'
.71 19.2 0.43
.41 1.511.04 1.45 40.012!.012 19.0 0.60
.49 2.072.04 1.92
+.0262.012 7/09/77
.68 20.5 0.32
.39 1.142.03 1.34
-0.0502.012 20.0 0.33
.56 1.842.04 1.95
.0162.012 7/16/77
.68 18.0-0.43
.42 1.09.03 1.00
+0.020.012 20.8 0.16
.42 1.901.04 1.78
+.023!.012 7/23/77
.68 20.0 0.24
.34 1.682.04 1.84
-0.0381.012 19.8 0.26
.25 1.18.03 1.00
+.060t.012 7/30/77
.68 19.5 0.24
.59 1.571.04 1.27 40.0432.012 20.0 0.10
.36 1.242.03 1.27
.006.012 8/06/77
.68 20.0 0.50
.51 1.75!.04 1.75
.000!.009 20.0 0.18
.36 1.172.03 1.27
.0232.012 8/13/77
.71 20.0 0.46
.27 1.122.03 1.11
+0.0031.012 20.0 0.25
.47 1.701.04 1.70
.00 2.012 S/2 7
.68 20.0 0.43
.42 1.91!.04 1.90
+0.0022.009 20.0 0.58
.46 1.642.03 1.40
+.0462.021 1.90
-0.01 !.010 20.0 1.08 40 1.292.03 1.20 0302.020 3/27/77
.68 16.9 0.34
.44 1.84.04 9/03/77
.68(13 9.3 0.38
.42 1.30!.04 1.35
~+0.00 t.010 20.0 0.55
.54 1.78.02 1.83
.020t.010 1
9/10/77
.68 19.2 0.40
.39 1.68!.04 1.58
+0.020!.010 19.6 0.31
.30 1.205.03 1.15
+.011!.010 9/17/77
.68 19.5 0.24
.50 1.74!.04 1.73
+0.001.006 20.0 0.36
.33 1.28.03
'1.20
+.015.010 9/24/77
.68 19.6 0.22
.43 62
.23 1.33 14.8
~2.7 20.0 0.18
.52 21.3 1.-5.
1.33 3.9 2.1 N
Q u
a U
(1) e-AU =.57 at Steinbrink for this sample.
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Table C -- Measured and Predicted Iodine-131 in Milk at Zion, Illinois FARM:
8000m West FARM: 16200m NNW a
Date Measured,pCi/l Predicted,pCi/l Measured,pCi/l Predicted.pCi/1
.000 1.007
.004
.004 1.012e
.0005 6/15-6/21 6/22-6/28
.001 1.012 0
.119
.012
.00002 6/29-7/5
.012 2.012 0
.026 !.012
.0001 7/6-7/12
.050 2.012
.002
.016 2.012 0
7/13-7/19
.020 2.012
.0009
.023 !.012
.0004 7/20-7/26
.038
.012
.0006
.060 2.012
.0002 7/27-8/2
.043
.012
.002
.006 !.012
.00003 8/3-8/9
.000 !.009
.0004
.023
.012 0
8/10-8/16
.003 !.012
.003
.00
.012 0
8/17-8/23
.002 1.009
.0004
.046 2.021 0
8/24-8/30
.01 2.01
.00005
.030 !.020
.0001 8/31-9/6
.00 2.01 0
.020 1.010
.00001 9/7-9/13
.02 2.01
.0004
.011 1.010
.0003 9/14-9/20
.001
.006
.001
.015 !.010
.0003 N
a The year is 1977 b North northwest c One standard deviation of the radioactivity count 1578 344 _.
a TABLE D -- Measured and Predicted Concentrations of Tritium at Zion Station b
Incremental Predicted conc.
Measured c
Plant r-conc. nt Ambient at public water conc. at f
Discharge public water intake, Lake Michigan
- intake, public water Period C
Co1ACo<C conc, C C
C intake d o
o o
o M
g Co+g C +W a
O Third Calendar 475 81 ACo i 16 236 i 95 244!95 252195 200 2 100
- Quarter, 1977 8
Fourth y
- Quarter, 360 61 ACo 1 12 232 48 238148 244 48 253 1 70 1977 First
- Quarter, 405 71 Aco i 14 231 1 40 238240 245140 320 1 60 1978
- Concentrations are given in pCi/1, and, if available, ! two standard deviations of the radioactivity count.
b t;,
See text of paper for derivation.
N CI)
Based on grab samples collected weekly at five locations.
d t,.
Based on continuous sample.
_pm LJ1
O ENVIRONMENTAL DOSE PATHUAY STUDY AT DRESDEN NUCLEAR POUER STATION Spring 1978 through Spring 1979 Studies being conducted at Dresden Nuclear Power Station began in the Spring of 1978 and have the same objectives as the study at Zion Station plus a source term study to measure releases from the station under a variety of operating conditions.
The program is now operational and data are being accumulated on a routine basis, but interpretation of the data have not been undertaken.
The status of each phase of the program is discussed below.
1.0 Source Term Study Introduction The objective of the source term study is to measure the amounts of radioactivity released from the station under a variety of operating conditi'ons and to compare the values obtained in the study with those used in mathematical models and provided by other types of measurements. To accomplish this, effluent media are being sampled and their dose-producing radioactivity being measured.
1.1 Photon Emitting Noble Cases in Chimney Cas Chimney gas is to be sampled during routine operation; use of vacuum pump at startup, power level increase, and refueling. The sampling point is the chimney particulate sampling station (isokinetic sampler) after filtration.
One liter of gas is collected in a gas Marinelli beaker by pumping gas through the Marinelli for about 5 minutes. The samples are analyzed for radioactive noble gases by gam =a spectrometry shortly after collection and about one day latere.
Data [ tom samples collected have not as yet been quantified, but the expected nuclides (Kr-85m, Kr-88, Kr-87, Xe-133, and Xe-135) were clearly detected.
1.2 H-3 in Non-Water Forms, C-14, and Kr-85 in Chimney Cas Samples are taken on the same occasions and at the same location as in 1.1 above.
ei 1578 540 s
Collection is made by drawing chimney gas into an evacuated container
(> 101). The gas will be analyzed for C-14. H-3 in non-water forms and Kr-85. Samples have been collected but have not as yet been analyzed. A gas processing system has been designed and is being constructed.
1.3 Radioactive Noble Cases, C-14, and H-3 in Non-Water Forms in Reactor Building Vent Gas Samples are collected at the reactor building vent particulate sampling stations during routine operation, during removal of the reactor-vessel head, refueling, and during transfer of used reactor-water demineralizer to tank.
Xenon is collected on activated charcoal at low temperature as described below and a sample for the other radioactive components is collected in the same manner as in 1.2.
l.3.1 Collection and Analysis of Radioactive Xenon in Reactor Building Vent Gas The sample collecting system is shown in Figure C. The sample gas passes from the sampling port first through the flow meter. Pressure in the floumeter is within one cm of ambient and therefore no significant volume correction need be made. From the flow meter the. sample passes through a 13X molecular sieve column which removes CO2 and H 0. A precooler consisting of a 3 meter 2
copper coil immersed in dry ice slurry (-760c) chills the gas prior to entry into the sample trap (activated charcoal) which is also immersed 'in dry ice slurry. The remaining gas then passes through a heat exchanger and into the air mover. The charcoal containing the xenon is transferred to a sealed con-tainer and counted on a gamma spectrometer about one hour and one day after collection. Between counting periods, the sample is stored at
-760 to minimize migration of xenon off the charcoal.
Measurements on samples collected have clearly detected Xe-133 and Xe-135.
The quantitative aspects of this phase of the program must await the issuante of Xe-133 standard reference material which will not take place until February, 1979.
1.4 Tritium in Water Vapor in Chimney and Reactor Building Vent Gas 4.
This phase of the program is partially under way since chimney gas is presently being sampled and analyzed for tritium. The program is hindered by the following problems:
Moisture content of the air is generdily low, a.
requiring extended sampling periods.
g
.s 1578 547 l
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___ _ _ d.b W 4
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b.
Plant equipment for measuring moisture content-of chimney and vent gases is not functioning.
The most reasonable approach to obtain the data required in the program is to determine the specific activity of the water in the effluent gases and estimate releases from measurements of the total water released through this pathway, since quantitative collection and recovery of water vapor is very difficult and it is virtually impossible to calibrate any system divised under actual operating conditions.
Suitable access to all sampling locations is not c.
avhilable.
1.5 Alpha Emitters in Chimney and Reactor Building Vent GasesThese samples are collected at the usual sampling locations for particulates by station staff. The filters will be analyzed for transuranics.
Appropriate station personnel have been contacted and requested to provide the samples.
1.6 Noble Cases, C-14 and H-3 in other Airborne Discharges Samples of head-space gas are to be collected from the contaminated liquid waste storage tank vent line during filling. As of this writing sampling systems have been constructed, sampling equipment assembled, campling points located, and analysis systems designed. No samples have as yet been collected.
1.7 Non-photon Emitting Radionuclides in Reactor-System Liquid Wastes Samples from the waste sample tank will be analyzed for alpha emitters, P-32, and C-14. The samples will be collected by station staff prior to releases from the tank and analyzed by standard procedures. No samples have been collected as of this writing.
1.8 Radioactivity in Minor Unmonitored Plant Effluents Samples of the following effluents are collected:
a.
discharg..d service water
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The samples will be analyzed first for gross beta concentrations and If sample gross beta activity exceeds background or reference tritium.
location levels, they will be analyzed for gamma emitters by ga=ma spectrom-etry.
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2.0 External Dose Study 2.1 Thermoluminescent Dosimeter Readings Thermoluminescent Dosimeters (TLD) are emplaced at 16 locations surrounding the plant approximating one location per sector used for dose calculations. Locations are given in Table E and Figure D. TLD badees re-main on station for three months. Exposures are measured and comsared with doses calculated froe release and meteorlogical data, gamma surs ey data (See 2.2) and where possible, data from pressurized ion chambers (See 2.3).
These comparisons will be made on both a quarterly and annual basis.
2.2 Gamma Survey Readings Gamma survey readings are made at each of the TLD stations on alter-nate weeks using a survey meter with 2" x 2" NaI (T ) crystal shielded with 2
cadmium to minimize response to energies below about 80 kev. The system yields a count rate of about 4000 counts per minute when the pressurized ion chamber indicates a dose rate of about 8 pR/hr. The gamma readings, with adequate intercalibration with the PIC, should provi's additional information on the natural background dose rate at the TLD stations and may therefore enable measurement of doses due to station releases at these locations to be calculated.
2.3 Pressurized Ion Chamber Meusurements (PIC's)
PIC's have been installed at two locations roughly 1300 apart. The objectives and methods of the PIC program at Dresden are essentially the -
same as those for the Zion program. The PIC's were installed in the spring of 1978 and after some initial equipment and data processing problems have been providing dose information on a regular basis.
3.0 I-131 Air to Milk Pathway Study Large volume (-20 L) milk samples were collected as weekly composites of daily samples beginning in April 1978 and processed ta measure I-131 concen-trations. The samples were collected from one farm about 6 miles NNU of the station, and another about 16 miles distant in a NE direction. The objectives and methods were essentially the same as those detailed in the Zion program.
N Radioactive iodine was detected at low concentrations in most samples.
The activity was confirmed to be I-131 by gamma spectrometry and decay samples.
4.0 Aquatic Pathway Study The aquatic pathway study at Dresden consists of measurement of radio-activity in edible fish tissue. The major radionuclides examined are I-131, Cs-134, Cs-137 and P-32. Samples from upstream and downstream of the plant have been analyzed. The data have been evaluated only to the extent of deter-mfning that the results of analyses were valid analytical data and not as they relate to the study.
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4 5578 550 Figure C - Xenon Extracti >n System Dresden EDPS Program
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ENVIRONMENTAL DOSE PADNAY STUDY AT THE QUAD CITIES STATION The study to be conducted at the Quad Cities station is scheduled to take place in 1979-1930.
The four projects selected for study at Quad Cities consist of:
1.
a source-term study to measure airborne effluents in the chimney, the reactor-building vent, and other ventilating systems, with special emphasis on the noble gases H-3, C-14, and alpha-particulate emitters; main liquid effluents with special regard to radionuclides that do not emit gammt rays; and minor effluents that are believed to contain few or no adionuclides from station operation. These measurements, undertaken with grab samples on selected occasions, should indicate whether routing source monitoring of these sources will be desirable or unnecessary; 2.
an external dose study, to test a system that combines thermo-luminescent dosimeters, pressurized ionization chambers, and survey meters at locations that encircle the station to measure radiation exposure from airborne effluents in the 1-10 mR/yr range; 3.
an I-131 air-to-milk pathway study, to measure actual I-131 concen-trations in the milk of cows pastured near the station for the entire grazing season, and relate these values to I-131 release rates; 4.
an aquatic pathway study, to compare the predicted critical radio-nuclides in fish and in drinking water at concentrations derived from the pathway model with measured concentrations.
The survey methods, sample collection and analytical procedures will be essentially the same as those employed in the Zion and Dresden programs incorp-orating'any modifications determined to be helpful or necessary.
Sincekwork is not scheduled to commence until 1979, only minor preliminary tasks such as selecting the locations of TLD installation sites have been undertaken at this writing.
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