ML20056F997
| ML20056F997 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 08/26/1993 |
| From: | PORTLAND GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20056F992 | List: |
| References | |
| PROC-930826, NUDOCS 9309010135 | |
| Download: ML20056F997 (13) | |
Text
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l Trojan Nuclear Plant Document Control Desk-j Docket 50-344 August 26, 1993 j
License NPF-1
' Attachment-
.l 10 Pages 1
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i Changes to the Offsite l
Dose Calculation Manual-i Revision 9 March 1993 l
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9309010135 930826 gDR ADOCK 05000344 2
PDR-
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1.0 INTRODUCTION
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l The purpose of this manual is to provide methods for demonstrating fj compliance with the surveillance requirements of the Technical Specifications regarding radioactive effluents.
Each method is based on l
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Plant-specific applications of the dose models presented in Regulatory Guide 1.109 (Rev. 1, 10/77), and/or the simplified dose models presented l
j in NUREG- 0133 (10/78).
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1-1 Amendment 9 (February 1993)
i 2.0 LIQUID EFFLUENT DOSE CALCULATIONS 1
2.1 TNTRODUCTION Cumulative quarterly dose contributions due to radioactive liquid efflu-
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ents released to unrestricted areas will be determined at least once
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per 31 days when the cumulative liquid activity release, excluding j
tritium and dissolved gases, exceeds 2.5 Ci/ quarter. These dose contri-butions will be calculated for all radionuclidos identified in liquid effluents released to the unrestricted area using the following general equation (
Reference:
NUREG-0133, pg. 15):
15 A
[ AT C F
(2-1)
D)={
g gg where D = the cumulative quarterly dose commitment to any organ j, from liquid effluent for total time period [ AT, in mrem g
1 g = the length of time over which Cgg g
and F are averaged, AT in hours gg = average concentration of nuclide i, dt :ing time period AT,
C g
in pCi/ml. The term C is the undiluted concentration of yg radioactive material in liquid waste deletnined in accordance with Table 4.11-1 of the Technical Specifications q = ingestion dose factor for any organ j, for each identified A
nuclide i, listed in Table 2-1, in mrem /hr per pCi/ml l
during any Fg = the near field average dilution factor for Cgg liquid release.
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2-1 Amendment 9 (February 1993) j
The term F, the near field average dilution factor, is determined as g
follows for time period AT :
g liquid radioactive waste discharge volume 7
total Plant discharge volume x Plant dilution factor The Plant dilution factor accot. its for mixing effects of the dilution pipe. This value is determined in accordance with IMREC-0133, Page 16, as equal to:
1000 cfs
= 19.26 average total Plant discharge The average total Plant discharge of 23,803 gpm is the historical 7
average for the years 1976-1985.
y3, the ingestion dose factors for any organ, are tabulated The term A in Table 2-1.
For simplicity and conservatism, a single maximum organ dose factor for each nuclide was calculated using the critical organ for each nuclide. The following equation was used in calculating the ingestion dose factors (
Reference:
NUREG- 0133, pg.16):
h g = k, h+U A
BF p
i DF
~
D i
g where A
= composite dose parameter for total body or maximum organ g
of an adult for nuclide 1 in mzem/hr per pCi/ml 5
6 3
k = conversion factor, 1.14 x 10 = 10 pCi/pci x 10 ml/kg + 8760 hr/yr Up = 730 kg/yr, adult maximum annual water consumption rate (from Regulatory Guide 1.109, Rev. 1, 10/77, Table E-5) 2-2 Amendment 9 (February 1993)
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2.5 TECHNICAL SPECIFICATION 6.9.1.5.4 This section describes the method that will be used to calculate doses i
from liquid effluents, as required by Technical Specification 6.9.1.5.4 (Semlannual Radioactive Effluent Release Report).
2.5.1 GENERAL METHODOLOGY l
i The models of Regulatory Guide 1.109 (Rev. 1, 1977) will be utilized, incorporating Trojan site-specific modeling parameters, to compute doses from liquid effluents for this Technical Specification.
In addition to the four principal Regulatory Guide 1.109 liquid effluent dose pathways, g
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a PGE-developed swimming immersion dose pathway has been added to include radiation exposure to swimmers in the Columbia River.
The PCE computer codes utilized in these calculations are documented, validated and controlled in accordance with written, quality-related procedures.
i 2.5.2 PLANT / SITE-SPECIFIC ASSUMPTIONS l
Hydrologic dilution factors will be based on actual river flow rates and effluent flow rates during the reporting period.
Drinking water and agricultural exposure pathways will assume dilution into the full river flow.
Other exposure pathways will assume dilution into the Plant mixing zone, which is defined as that portion of the river from the Oregon shore to a point 300 ft from the end of the active region of the diffuser pipe.
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2-9 Amendment 9 (February 1993)
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l 3.0 GASEOUS EFFLUENT DOSE CALCULATIONS
3.1 INTRODUCTION
The noble gas dose rate contributions may be determined using the follow-13 l
ing general equations (adapted from NUREG-0133, Sections 5.2.1 and 5.3.1):
15 I
Gamma air dose rate, D, mrad /yr D = 1000 I N xQ C3~1) g TV B
Beta air dose rate, D,, mead /yr D,=1000{My xQ (3-2) 1 i
Skin dose rate, D, mrem /yr 3
D3=1000{(L+1.1xN{x Q (3-3) g Total body dose rate, DTB' Y#
TB "
ki*OTV D
( ~4) i i
where Kg = total body dose factor due to gamma emissions for nuclide 1, rem /yr per Ci/see Lg = skin dose factor due to beta emissions for nuclide i, rem /yr per Ci/sec My = air dose factor due to beta emissions for nuclide i, rad /yr per Ci/sec 3-1 Amendment 9 (February 1993)
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Ng = air dose factor due to gamma emissions for nuclide 1, rad /yr per Ci/sec (note that these are " air" rads not " tissue
=
E j
rads) l l
Q
= noble gas activity release rate of nuclide i, Ci/sec g
i t
1000 = constant, mead / rad or mrem / rem th t
1.1 = constant, the average ratio of tissue to air energy absorption a
coefficients with the u:.its of rem /" air" rad.
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The values of K, L, M, and N are listed in Table 3-1.
Derivation of g
g g
g these values is presented in Appendices A and C.
l The 1-131, tritium, and particulate (Tg > 8 days) dose contributions may be determined using the following general equation:
l DIPC = 1000 1 Ri x Qi (3-5) i i
I l
l where l
DirC " d ** "*t* *t * "'" lli"5 **P 8""*
1
- ti "' ""**'Y" i
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Rg = dose fact :r for nuclides other than noble gases at the control-ling exposure Incations (as determined in the Annual Land Use l
Census) for critical organ and age group, rem /yr per Ci/sec t
Qg = I-131 and particulate activity release rate of nuclide i, ci/sec.
t_c:
The values of R are listed in Table 3-2.
Derivation of these values is presented in Appendix B.
As noted in Appendix B, the R values of Table 3-2 g
a are from the 1984 Land Use Census, and these values are still appropriate as
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determined by the 1986 Land Use Census. The R values listed in Table 3-2 g
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are composites of the pathway-specific R values developed in accordance g
l with Regulatory Guide 1.109 methodology.
3-2 Amendment 9 (February 1993)
3.7 TECHNICAL SPECIFICATION 6.9.1.5.4 This section describes the method that will be used to calculate doses from gaseous effluents, as required by Technical Specification 6.9.1.5.4 (Semiannual Radioactive Effluent Release Report).
3.7.1 GENERAL METHODOLOGY The models of Regulatory Guide 1.109 (Rev. 1, 1977) will be utilized, i
incorporating site-specific modeling parameters, to conpute doses from I
gaseous effluents for this Technical Specification. The PGE computer
}5 codes utilized in these calculations are documented, validated and controlled in accordance with written, quality-related procedures.
3.7.2 PLANT / SITE-SPECIFIC ASSUMPTIONS Meteorological dispersion and deposition factors will be based on hourly meteorological data from the Trojan meteorological monitoring system i
during the reporting period. Separate meteorological factors will be l
derived for batch and continuous releases.
The meteorological model described in Appendix C will be used.
Dose receptor locations will be based on the results of the Annual Land Use Census'(required by Technical Specification 3.12.2) for the previous year except as-described in Section 3.1 and Appendix B.
i The methodology described in Appendix D will be used to assess the radiation doses from radioactive effluents to individuals due to their activities inside the unrestricted area boundary during the reporting period. This assessment will account for current meteorological data, changes in occupancy times and locations, and will be documented and fh verified in accordance with written departmental or. branch procedures.
The results will be reported in the Semiannual Radioactive Effluent Release Report.
3-10 Amendment 9 (February 1993)
M meat ingestion pathway dose factor for nuclide i, R
a y
l.:=
2 mrem /yr per Ci/m -sec Ry = cow or goat milk ingestion pathway dose factor for If C
2
^
nuclide 1, mrem /yr per Ci/m -sec I;$
i atmospheric dispersion factor for continuous x/Q
=
3 i
releases at controlling exposure location, sec/m l
atmospheric deposition factor for continuous D/Q
=
releases at controlling exposuro location, m~
10~
constant, rem / mrem.
=
i I
G V
M C
The dose factors, R, R, E, R, R were derived as follows and are g
g g
g listed in Table B-1.
I Inhalation Pathway Dose Factor R g
t l
R = 1012(BR) (DFA )
(B-2) l}h I
g i
where t
i 10
= constant, pCi/Ci (BR) = breateing rate of the receptor of child age group = 3700 m /yr (Regulatory Guide 1.109. Rev. 1 j
l 10/77, Table E-5)
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(DFA ) = maximum organ inhalation dose factor for the receptor g
for nnelide i, in mrem /pCi (Regulatory Guide 1.109, Rev. 1, j
10/77, Table E-9).
The total body is considered as an organ in the selection of the DFA.
g B-2 Amendment 9 i
(February 1993)
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r = fraction of deposited activity retained on goat's feed grass, 1.0 for iodine. 0.2 for particulates (Regulatory cuido 1.109, Rev. 1, 10/77. Table E-15) tg = transport time from pasture to goat, to milk, to receptor, 5
1.73 x 10 sec (2 days) (Regulatory Guide 1 109 Rev. 1, 10/77 Table E-15) h = transport time from pasture, to harvest, to goat, t
7.78 x 10 sec (90 days) (Regulatory Guide 1.109 Rev. 1,
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10/77, Table E-15) 10
= constant, pCi/Ci and all other terms have been previously defined.
Grass-Cow-MilkPathwayFactorRf
-A g ~
g 9
p's
( ~'p's *
~if C
12 F ap Rg = 10 (F )(r)(f,)(DFL )
+
e Ag + 1, Y
Y, (B-9) where w's ns mption rate of feed, 50 kg/ day (Regulatory Q
=
F Guide 1.109 Rev. 1, 10/77, Table E-3)
U
= child receptor's milk consumption rate, 330 1/yr (Regulatory Guide 1.109 Rev. 1, 10/77, Table E-5)
Y, = agricultural productivity by unit area of stored feed, 2.0 kg/m (Regulatory Guide 1.109 Rev. 1, 10/77, Table E-15) i B-8 Amendment 9 (February 1993)
s F,, stable element transfer coefficient for milk, in j
days /1 (Regulatory Guide 1.109, Rev. 1, 10/77, Table E-1) i r = fraction of deposited activity retained on cow's feed grass, 1.0 for iodine. 0.2 for particulates (Regulatory Guide 1.109, j
Rev. 1, 10/77, Table E-15)
I g = transport time from pasture to cow, to milk, to receptor, j
t 1.73 x 10 see (2 days) (Regulatory Guide 1.109, Rev.1, 3
10/77, Table E-15)
I t = transport time from pasture, to harvest, to cow, 7.78 x 10 sec (90 days) (Regulatory Guide 1.109, Rev. 1, 10/77, Table E-15) 10
= constant, pCi/Ci and all other terms have been previously defined.
The concentration of tritium in milk is based on the airborne concen-tration rather than the deposition. Therefore, the R for tritium is based on x/Q:
I'g
,3 = (10 )(10 )F Q UF n(DFL ) [0.75(0.5/H)]
(B-10) g where all pm ameters have been defined previously.
Determination of controllinz Exposure Location The controlling exposure location is that offsite location where the combination of existing pathways and annual average meteorology would indicate the maximum potential dose.
That is, the controlling. exposure individual is assumed to breath the air at the nearest residence with the
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highest x/Q value, to reside at the nearest residence with the highest B-9 Amendment 3 (February 1993)
E. DIRECT RADIATIONDOSES FROM TIIE FACILITY Unrestricted area Thermoluminescent Dosimeter (TLD) measurements are used to access the impact of the operational activities of the Trojan Nuclear Plant on ambient radiation levels. TLDs are placed in a ring around the plant, in both onsite and offsite locations, at distances from 0.1 to 1.6 miles For sources of direct radiation from the facility, TLD measurements indicate that total body doses to individuals in unrestricted areas are zero.
If there is a significant direct radiation component, as measured by an unrestricted area TLD, the dose of the individual most likely to receive the highest exposure will be added to the dose from the effluent pathways.
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F. ASSESSMENT OF DOSES WITIIIN TIIE UNRESTRICTED AREA BOUNDARY An assessment of doses to individuals utilizing unrestricted areas within the Trojan Nuclear Plant Site Exclusion Area Boundary was performed for the first and second l
quarters of 1993. Specific locations considered included occupational areas outside the restricted area boundary and recreational (i.e.,public access) areas located at the site.
j The methodology contained in Appendix D of PGE 1021, the Offsite Dose Calculation l
Manual was followed. Occupancies of 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> per year for occupational locations and 1,530 hours0.00613 days <br />0.147 hours <br />8.763227e-4 weeks <br />2.01665e-4 months <br /> per year for recreational locations were assumed. Location directions and downwind distances are tabulated below.-
ONSITE DOSE LOCATION CONSIDERED i
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ASSUMED OCCUPANCY DISTANCE OCCUPANCY FACTOR
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SECTOR (meters)
(hours / year)
(hours /8760) i l
SSE 286 1530 0.17
)
S 218 2000 0.23 SSW 150 2000 0.23 SW*
122 2000 0.23 WSW 122 2000 0.23 l
WNW 300 2000 0.23
- Maximum location Quarterly atmospheric diffusion factor (X/Q) values at the locations ofinterest were obtained, corrected for occupancy, and compared to the site boundary values at locations of maximum concentration.
Result The highest onsite doses for the first quarter of 1993 were at the occupational location approximately 218 meters south of the plant vent and were calculated to exceed those at the site boundary by a factor of 1.50. The highest onsite doses for the second quarter of 1993 were at the occupational location approximately 122 meters southwest of the plant vent and were calculated to exceed those at the site boundary by a factor of 2.36. These factors are quite conservative due to the assumptions of Gaussian plume dispersion and ground level releases so close to the plant vent; nonetheless, doses to workers not monitored for radiation exposure are small fractions of Technical Specification limits for unrestricted areas. Doses to the maximum publicly accessed recreation area were determined to be less that those at the site boundary for both calendar quarters.
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