' ' • Nndear Science and Technology, V o U , No. 4 ( 2 0 1 4 X B > . 09-16
Assessment of radiation dose caused by radioactivegaseous effluent released from nuclear power plant Ninh Thuan 1
under scenario of normal operation
Do Xuan Anh. L e Dinh Cuong, Duong Due Thang, Vuong Thu Bac, Nguyen TM Thu Ha Nguyen Quang Long, Trinh Van Giap, Nguyen Hao Quang*. Nguyen Tuan Khai
'•^tide for Nuclear Science and Technology (msi), 179 Hoang QuocrM, Hanoi
*rKtnon, Atomic Energy Institute (VINATOM), 59 Ly ThuongKlet, Hanoi (Received 15 December 2014, accepted 23 Januaiy 2015)
' ^ T ' ^ T f . ^ r " ' ' ^° ' • " " • ^° ' • " ' »"'•"*'»' "^ " " ' = « «•»"» Nuclear Regulator.
Commission (USNRC)ourresearehconcentralesh»ssessmg radiation d o ^ caused by l a d S c t i v ^ substances released fiom die nucleai power plant (NPP) Nmh TTiuan 1 mider die scenario of nomial operatmn using software package NRCDos.72 provided by die USNRC The database mcluding die released radioactive nuclides, meteorology, t e ™ n , population and agricnltural production ro^dtituti ^ ' = ° " " = « f - ' ' r ° " « ' » « * = i-^ut data tc^themodel calculation^he wind rose distnbution obtamed liom die meteorological data m a five-year period from 2009-2013 showed ta die rad,o«ve nuclides released to »viromneM spread m two main wind directions which are NoittEast and SouU, West. I h e X/Q (s/m') and D,Q (s/m=, qualities which are. respectively, tiie ratio I t r e r r r ^ J " " ' " " • " ' ° " ' ' ^ ' ° ' ' ' ' ^ ° * " ' ' ' - ' ^ ° ' " " ° « « ™ - " ^ ^ ^ ^ ^ mK were calcnla«d ^ d m i an are. of 80 km radius fiom die NPP site using XOQDOQ. Population S c D r , ; : ' : t " " ' - ^ ° ^ " " ^ ^^^ ™ ' ' " ° « - ^ ° ^ ' - - - spedftc'^softles in Keywonls: NPP, radioactive release, radiation dose, population dose. X/Q andD/Q
L m T R O D U C r i O N support for regulatory organization in Cunentiy, Vietnam is actively preparing ' ^ " = » ™ « ""= ^'^^^ A n a ' ^ i s Report (SAR).
infrastructure forthe first two nuclear power Radioactive releases from various plant (NPP) projects Ninh Thuan 1&2 which is ""elear facilities, in general, may oonttbute to planned to build with a total capacity of 2.000 ladiation exposure through two mam M W for each. When going mto operation, the pathways: (1) Extemal exposures by direct NPP will.»^lease radioactive nuclides into the radiation from radioactive plumes or from atmosphere. The ladioactive effluent mdioactiye nuclides deposited on the ground undergomg dispersion m au- and deposition on ^ d (2) Internal exposure due to mhalation and ground win cause impact to the environment ingestion of ladioactive substances The and human. Therefore, researeh for ttansport magnitude of exposme is dependent on and dispeision of radioactive substances m atinospheric dispersion and deposition atmosphere, and assessment for radiation dose processes,
to die public ate of essential requirement for an I .u- j
NPP project, to addition, the calculation results Uie , 1 ' ™ f . " ' ° * ™ " ^ ' ^ ^ investigating will provide the necessaty data f o r t e ^ ^ " " T "^' * ° " * = ^ ' ' NM>
Envinimnentid Impact A a ^ m e n t (EIA) and ' ^ t i " " ' , " ' ' " ' ^ 8 ™ " ^ « ™ ""^^^for the
^ J ™ populationmtder the scenario of nonnal O2014 Vietn«n Atomic Energy Society and Vietiiam Atomic Eneigy I„iai„„e
ASSESSMENT OF RADL^TION DOSE CAUSED BY RADIOACTIVESii^Olffi EFFLUENT ... M locations speciSod by ^ useF,.8i^ ^t vstkuM standard radial distances uul segment ^m downwind sectors. Evaluations of anticipa^M intermittent (e.g. containnrent or pins&ll releases which occur during routine operatiM^
may also be evaluated using tbe program.
Evaluation of intermittent relrases providi botii X/Q and D/Q values at various standi __
locations, as well as user-inputted specific!
points of interest.
The input of the program incli meteorological and topographic Meteorological data is as a joint frequency table, i.e. a table of the fiactional occurrence i during a given time period of a particula combination of stability class type, wind direction, and wind speed class. The windj direction is classified into 16 proceeding clockwise fi-om N through The wind speeds are grouped into classes, wit!
the program allowing up to 14 separate classe^^
which include a class for calm wind speeds.1 Atmospheric stability is grouped according to' seven categories fi'om extremely unstable to|
extremely stable. Terrain elevation (in meter&«
compared to the factory floor) is the maxic height in the topographic data collected in ti»|
80 km radius firom the NPP site. The directiti^
and distance from the source are included ifl terrain elevation data.
soflware
NRCDose72.To build the data input for tiie model calculation the database on meteorology, terrain, population and agricultural production activities has been collected and processed within a radius scope of 80 km from the NPP site, where the wind rose distributionwas obtained firom processing the meteorological data in a five-year period of 2009-20l3.The released nuclear data is referred from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), in which the annual normalized release in Bq/(GW«-year) for the radioactive isotopes has been published for the popular reactor types such as PWR, BWR, FBR and some others based on the average evaluation on period from 1990-1997 [1,2]. Our assessments have been performed using the released data for PWR lype with an assumed total power of 2000 MW,,. The ratio of activity concentrations X/Q (s/m') and that of radioactive deposition densities D/Q (s/m^) were calculated using XOQDOQ, in which it is assumed that the radioactive substance is disperaed by the Gaussian model. The obtamed results on X/Q and D/Q values were used for evaluating tiie population doses using CASPAR. As mentioned above, the XOQDOQ and CASPAR are two softwares in NRCDose72 package [3,4J.
II. COMPUTER CODE DESCRIPTION A. XOQDOQ
Computation program XOQDOQ is used in die independent meteorological evaluation of routine or anticipated, intermittent releases of radioactive nuclides at commercial nuclear power plants. It is primarily designed to calculate annual relative effluent concentrations. X/Q values, and annual average relative deposition, D/Q values, at
In this work the meteorological data>a | Ninh Thuan including wind direction, w i i ^ | speed and atmospheric stability has b e ^ ^ collected and processed based on a five-ye^ | database provided by Phan Rang • meteorological stationand tiie Natioi^ p.
Oceanic and Atmospheric Administration (4, % United States (NOAA). The terrain data im built using the topographic map within the 80 i km radius around the site planned for NPP NinhThuan I.
DOXUANANHctaL The rahies 3WQ is Atenmiied by fc followiiig fiinmila [3]:
X e x p
where | { i , * 5
(1) aveiage eSuent conceolration nonnalized l y souice strength at tlislance i in directional sector K (s/m^); x is the downwind distance (meteis); j is the i*
wmd-speed class; yis fc j * atmospheric stability class; AT is fc k» wind-direction class;
Ulis mid-point value of to i" wmd-speeti cla.ss; 05fx> is fc vertical plume spread for stability class j at distance x; fgCK) is fc jomt probability of occunence of fc i* wmd-speed class, J* is stability class, and K" is wmd ditection sector; *, is fc effective plume height (in meters); D£C/x)is fc teduction ftctor due to ladioactive decay at distance x for fc i*
wind-speed class; DEPL(x.K) is the reduction fector due to plume depletion at distance x for fc i" wind-speed class, j * stabihty class and IC* wind-dirscdon class; RF(x,K)is fc correction factor for recuoulation and stagnation at downwind distance x and K*
wind-tlirection class.
relative For each directional sector,
computed by fc _ lelationship for a specific downwind distance [3]:
= fc« =
(2)where - ( X , J O is fc average relative deposition per unit area at a downwind distance x and direction K. in meter"^; D is fc relative deposition rale fijr fc i* wind-speed class and fc j» sOibility c l a s s ; / ^ ; B fc jomt
probirfa!^ of occtmraice pf fc i* wind-^teed etas; RFpiK) Is fc coirectioo feclor fcr lecBcQlatkHi and stagnatitHi at downwind distance X and K* wind-direction class.
B. CASPAR
GASPAR is a conqniter code used by fc USNRC in radiation dose assessment fer individuals and groups of people contammated by fc release of radioactive nuclides into fc air environnient of imclear power plants in normal toleration conditions. The theonitical basis for fc radiation dose calculations of fc code is based tm RegulaKny Guide 1.109 and NUREG/CR-4653 [5,6], Data mput of fc piogram fcludes:
(1) Population; Datii on fc total population and population distribution for four distinct age groups: mftnt, child, teenager and adultin each sector (subregion);
(2) Crop and cattle bree^ng: Data on production and distributions of rneat, milk and production.
These two data sets have been processed within fc 80 knuadius around fc NPP site.
(3) Radioactive release: Data on fc activily (Ci) of lieradioaetive nuclides released to fc environment and fc rate of fc ladioactive waste (Ci/year);
(4) Meteorology:
Data on atinospheric dispersion parameters (sec/m=) foruse in population dose calculations for fc nndecayed/undepleted dispersion and fc decayed/undepleted dispeision;
Data onatinospheric dispersion parameteis (sec/m') wifli decay and depletion for use m population dose calculations for fc decayed/depleteddispersion;
^ - Data on ground deposition parameter (m/year) for use mpopulatira, dose (^culations;
ASStSSNifcNT OF R.ADI.MION DOSb CAUSED BY RADIOACTIVEGASEOUS EFFLUENT . 1 should be noted ihai Ihe
meteorological data can be imported either directl\ mto the software or from ihe output of XOQDOO soflware
The outputs of GASPAR mciude - Gamma air and beta air dose:
- Annual effectne dose from all other noble gas releases.
- Skm dose.
Annual organ dose from e.xlemal irradiation by deposited radioactn'e nuclides;
- Annual organ dose from inhalation.
- Annual organ dose from ingestion of radioacii\e nuclides in food.
- Annual population mtegraleddose 111. RESULTS AND DISCUSSION A. Meteorological data processing
Pli;in R 2011') t pi oces^
.peed 1 the NP wind
IC ^MIKi rose (.(islribLiiioii oblained iram lhe 'tlliL-Phaii R:iiig>iaiion
sed on the dalabase provided b> Ihc lg station in the lue-vcar period from 201.1 lhe meteorological data was i to obtaiiiihe \s ind rose distnbution as
Hgure I foi the uind direction and the area planned for construction of Nmh Thuan I We can see that the rcciion and inlensily i. mainh
concentrated in two directions which are the North East and South West. These are the two mam wind directions passing through the provinces of the region in the South Central Coast and Tay Nguyen
At present it is impossible to determine the atmospheric stability from the Phan Rang station's database due to the lack of some necessary measurements such as the atmospheric temperamre as function nf height. We are discussing on a possibility to evaluate this parameter based on the cloud observation data In this work the atmospheric stability was evaluated usmg Ihe meleorological database downloaded from the National Oceanic and Atmospheric Administration (NOAA) ofthe United States, B. Gaseous effluent distribution
The output from the program XOODOQ was designed to present the maximum amount of infonnation on each release point, including' X/Q values (s/m^) at 22 specific distances ranging from 0 HO to 80 kmfroni the site;
- X/Q values for 10 distance intervals;
D/Q values (s/m') at 22 specilic distances ranging from 0 80 to 80 km from lhe site,
- D/Q values for 10 distance intervals;
- X/Q and D/Q values at specific points of interest
The obtained calculalion results made us possible to build the X/Q-value and D/Q-value distributions as a funclion of distance ranging from 0 8 to 80 km from the NPP site as shown in figure 2 We can see clearly thai the X/Q and D/Q values are dominant in two directions of North East and South Wesl This is consistent withthe obtained wind rose distnbution. where fhe wind frequencies arc also high in ihcse Iwo directions (as shown in ITeure I).
12
DO X U A \ ANH ei al.
Fig.2 Distribution on X-Q values (left) and D Q values |nghi) Withm 80 km radius from the NPP site C. Population dose assessment
The output of the program GASPAR gives the calculation results forthe annual total population dose and annual mdividual dose for
Table I: Calculat
three distinct age groups includinj teenager and adult at the locations of The details are given in Tables Mil.
radius
i child, interest.
ASSESSMENT OF R_ADi ATION DOSE CAUSED BY RADIOACTIVEGASEOUS EFFLUENT Table II: Calculation results for the annual tolal population doseinduced by the released radio-nuc Radioactive
nuclide
Annual total population dose (mSv) Li\ er Kidney Thyroid 3.49E-02 3.49E-02
2,30E-02 2 28E-0:
''Kr
'5 80E-02 9 80E-02 9 10%
~09E-00 07E+00 l,07E+00
n results forlheannual loial child, teenager and aduli;
effective dose to individual for three a It the locations of interest
L o c a t i o n
V m h T u o n g l Thuan N a m ) Son i-kii ( Thuan Nam ) T u l hicn 1 Thuan Nam ) BauNgu 1 Thuan Nam ) lloaThu_\ ( NinhPhuoc | Phuoc L.tp I Thuan Nam ) y u a n I h e l Thuan Nam | H i c u T h i e n ( Thuan N a m ) Thuong DiL-m ( Thuan Nam )
D i r e c t i o n
N S N N W N N W
N W W W'NW
sw
D i s t a n c e ( k m )
1 165 2 IS 3 38 5 9 9 1 I I 25 12 5 13 45 15 48
A n n u a l t o t a ! e f f e c t i v e dose t o i n d i v i d u a l for age g r o u p s ( m S v ) f o r age g r o u p s
Adult 1 46E-04 3 I5E-05 2 36E-0S 6 0 I E - 0 6 3 45E-06 I-96E-06 2 47E-06 1 61 E-06 1 58E-05
1 93E-04 4 I6E-05 3 I2E-[I5 7 92E-06 4 54 E-06 2 5 7 E-06 3.24L-06 2 I 2 L - 0 6 2 n9E-05
Child 3 I5E-(I4 6,77E-05 ' 5 071^05, 1 29E-05 1 7 34r.-l)6 4 15 E-06 5 231-:-06
3 41h-ll5
n s:'KW
!=i r.HiM A i^ac Tien ( Thuan Nam >
C a N a ( Thuan Nam) Phan Rang - Thap Cham Lien Huong (TuyPhong)
Thanh My ( Don Duong ) To Hap (Khanh Sou )
•! DO XUAN ANH etal.
WSW SW
N SW WSW
NW N NNE WNW
14.42 16.79 14.2 38.75 60.9 66.3 63.6 62.4 78
3.65E-06 1.38&05 1.98E-06 3.34E-06 3.1SE-07 I.02E-07 1.56E-07 4.61E.07 8.03E-08
4.S0E-06 1.83E-05 2.59E-06 4.41E-06 4.09E-07 1.31E-07 2.02E-07 6.03E-07 I.03E-07
7.7SE-06 2.99E-05 4.18E-06 7.19E-06 6.53E-07 2.08E-07 3.20E-07 9.69E-07 1.63E-07 We can see that the obtained results for
dose evaluatioo induced by die released radioactive nucUdes from the NPP Ninh Thuan I are much lower than the pennitted value of 1 mSv guided by NRC Regulations [7].
The amiual individual dose values given in Table m show a quicldy decreasing tendency with respect to distance, for example at Lien NgMa village which is nearly 80 km in the WNW direcHon from the NPP site the dose value is about 4 ordeis less than the dose at the Vinh Tuong, near the NPP site.
From the obtained calculation results shown in tables l-Ill we can see that:
- From tabie 1: Tlie dose induced by the ground deposiHon gives the greatest contribution, from 74.2% for diyroid to 93.6%
for bone, to the annual total population dose.
- From table 11: The radioactive isotope
""Co induces a greatest dose contribution, from 62 to 81%, tothe annual total population dose.
This is consistent with the real released data at nonnal operation conditions, where the "Co isconsidered as a typical representative for the radioactive nuclei produced finm neutron- induced activation reactions on the reactor core materials and moderatorand released via corrosion phenomenon [8]. Besides, the contribution ftom the fission products.
typically '"Cs, to the total dose is clearly proved.
- From table IH: The effective dose for the child is about 1.5 and 2 times, respectively, greater than those for the teenager and adult
Based on die calculation results for the annual dose evaluations obtained from analyzing the database and practical conditions in die area around die NPP Ninh Thuan 1 we can conclude diat die gaseous effluent release from die NPP satisfles die requirement on radiation safely for population and production activities in die nonnal operating condition.
JV. CONCLUSION We have buih the data inputs for two computer codes XOQDOQ and GASPAR based on collecting and processing a huge database mcludmg die data on population and population distribution for distinct age groups, the data on agricultural production activities,' the tenain data and die meteorological data in the five-year period 2009 - 2013.
The obtained calculation results for the annual total population dose and the annual individual dose at die specific locations within die 80 km radius frnm die site of NPP Ninh Thuan I showed Uiat under a nonnal operation scenario widi die routine release of radioactive nuclides ftom die NPP to die atinosphere all
ASSESSMENT OF RADIATION DOSE CAUSED BY RADIOACTIVEGASEOUS EFFLUENT ^ ^ the dose values are much less than the
pennitted hmit of 1 mSv.
The X/Q value and D/Q value distributions which are predominant in two directions of North East and South West are consistent with the wind rose distribution in the 80 km radius from the NPP site.
ACKNOWLEDGEMENT This work bas been performed in frame work of the National Program on Science and Technology in 2011-2015 Periodunder grant no.KC-05.04/ll-15.
REFERENCES
[IJ. "Exposures &om man-made sources of radiation", UNSCEAR Report Vol. 1, (2000).
[2]. "Radiation exposures in accidents", UNSCEAR Report Vol.2, (2008).
[3]. J. F. Sagendorf, J. T. Goli, and W. F. Sandusky,
"XOQIXJQ: Computer Program for the Meteorological Evaluation of Routine Releases at Nuclear Power Stations"; NUREG/CR- 2919; U.S. Nuclear Regulatory Commission, Washmgton, D.C; (1982).
[4]. GASPAR II - "Technics Re^pence a n ^ i Guide, NUREG/CR-4653; D. L A Bander, J. K. Soldat"; aS. Nuclear R Commission, Washington, D.C; (1987):
[5], Regulatory Guide 1.109 - "Calcul^eiBfl Annual Doses to Man from Routine £ of Reactor EfiQuents for &e Purpose ...f^^
Evaluating Compliance with 10 CFR" Part S Appendix I; U.S. Nuclear Commission, (1977).
[6]. Regulatory Guide l . U l - "Methods MM Estimation Atmo^heric Transport Dispersion of Gaseous Effluents in Routiilft,^
Releases from Light - Water - Codl^ -$| • Reactor"; U.S. Nuclear Regulatmy Commission, (1977).
[7]. Subpart D-"Radiation Dose Limits for ' Individual Members of the Public"; Part 20- Standards for protection against radiatiog;^
NRC Regulations (10 CFR). ,^ ^ „ [8]. "Manual for Reactor Produced Radioisotopes^,^^
IAEA-TECDOC-\340, P.O.Box 100, Vienna, Austria, (Jan. 2003).