Ten-year measurements of Radon's decay products to … Radioactive aerosols/All... · Ten-year measurements of Radon's decay products to study the role of atmospheric dispersion on

Ten-year measurements of Radon's decay products to study the role of atmospheric

dispersion on PM levels

R. Vecchi1, G. Valli1, V. Bernardoni1, and A. Franchin1

1Department of Physics, University of Milan, and INFN, via Celoria 16, 20133, Milan, Italy

Keywords: radon decay products, dispersion, PM

The measurement of the concentration and temporal behaviour of radioactive aerosol in atmosphere can provide information on atmospheric thermodynamic conditions as well as on atmospheric processes that involve aerosols such as transport, dispersion, removal rates and residence time.

Since 1997 our group has been measured the concentration of Radon's short-lived decay products routinely and continuously in Milan (Italy) with hourly resolution (Marcazzan et al., 1995; Sesana et al., 2003; Vecchi et al., 2004).

Radon activity concentration outdoor is detected through the collection of its short-lived decay products attached to aerosol particles and the spectroscopic evaluation of their alpha activity by a home-made instrument with high sensitivity (detection limit = 0.2 Bq m-3).

Long-term Radon measurements (Kataoka et al., 1998; Perrino et al., 2001; Sesana et al., 2003) show that the temporal variation of its concentration can give immediate information on the evolution of the stability conditions in the boundary layer. The stability conditions of the lower atmospheric layers, on a local scale, are very important as influence pollutants concentration on different time scales. Indeed, the dilution of pollutants in the mixing layer must be ascribed to thermal and dynamic turbulence, whilst the horizontal transport of pollutants is due to the wind field. In the Milan area and in the whole Po valley ventilation is scarce (despite sporadic advection episodes, typically Föhn events) and vertical dispersion plays the main role.

From long-term measurements performed in Milan by our group a typical daily pattern in Radon concentrations can be singled out: it is generally characterised by a minimum in late afternoon and a maximum in the early morning. This pattern is observed on sunny days with clear sky (both during day and night) and low ventilation rate and it occurs very frequently in Milan during both winter and summer months. The nocturnal accumulation of Radon is due to the low mixing layer generally caused by a low-height or ground-based temperature inversion of radiative origin. The variation of Radon concentration observed between the minimum in the afternoon and the maximum in the following day is a good indicator of the nocturnal mixing layer depth. When the sun rises in the morning and heats the

ground the inversion is destroyed so that the re-mixing of Radon takes place in layers of increasing heights causing a decrease of its concentration levels. The minimum concentration is registered during the afternoon when the mixing layer reaches its maximum depth. The variation between maximum and minimum Radon concentration in the same day is an index of the maximum height of the mixing layer, which has been evaluated by means of a box model suitably set up (Pacifico, 2005).

The analyses performed on our long-term dataset have been singled out a significant correlation between PM10 and 222Rn daytime concentrations evidencing the dominant role of atmospheric dispersion in determining the temporal variation of PM10 levels. Whenever 222Rn concentrations accumulate during the night (indicating the formation of a nocturnal atmospheric stability), PM10 concentrations show higher values than those registered during the daytime before, despite a nocturnal decrease in emissions from active sources. On the contrary, when 222Rn concentrations do not accumulate during night hours, PM10 levels are lower than those measured the daytime before. It is worth noting that in both cases the aerosols residence time plays a role and has to be taken into account.

Moreover, an analysis of the relationship between PM and atmospheric dispersion over the ten-year data set will be presented. Kataoka, T., Yunoki, E., Shimizu, M., Mori, T., Tsukamoto, O., Ohhashi, Y., Sahashi, K., Maitani, T., Miyashita, K., Fujikawa, Y., Kudo, A. (1998). Boundary-Layer Meteor., 89, 225–250 Marcazzan G.M., Mantegazza F., Astesani R. (1995). Life Chemistry Reports 13, 151-158. Perrino, C., Pietrodangelo, A., Febo, A. (2001). Atmos. Environ., 35, 5235-5244 Sesana, L., Caprioli, E., Marcazzan, G.M. (2003). J. Environ. Radioact., 65, 147-160 Vecchi, R., Marcazzan, G., Valli, G., Ceriani, M., Antoniazzi, C. (2004). Atmos. Environ., 38, 4437-4446

Cite abstract as Author(s) (2009), Title, European Aerosol Conference 2009, Karlsruhe, Abstract T121A01

FACTORS CONTROLLING 7Be AND

210Pb ATMOSPHERIC DEPOSITION AT MALAGA (SPAIN)

C. Dueñas, M.C. Fernández, S. Cañete, E. Gordo and M. Pérez

Department of Applied Physics I, Faculty of Sciences, University of Málaga. 29071 Málaga (SPAIN)

E-mail: [email protected]

Keywords: atmospheric aerosol, deposition,7Be, 210Pb, precipitation

ABSTRACT.-Bulk atmospheric deposition of 7Be

and 210Pb has been measured at Málaga (4º 28′ 80″

W; 36º 43′ 40″ N) a coastal Mediterranean station in

the south of Spain, from January 2005 through April

2008 for monthly periods. The fluxes of7Be and 210Pb

were mainly correlated with rainfall and correlated

one with the other .Concentrations of 210Pb and Ca++

in rain were correlated with transport time of air

masses over the continent

INTRODUCTION Berylium-7 is one of the

radionuclide produced by spallation reactions of

cosmic rays with light atmospheric nuclei.7Be rapidly

associates primarily with submicron-sized aerosol

particles. Lead-210 which is one of the natural

radionuclide of the 238U decay series is widely used

as a tracer. 210Pb depositional pattern gave us

information on continental aerosols in lower

troposphere. These two radionuclides with their

different sources and therefore are useful to

understand the mechanisms of aerosol removal from

the atmosphere. These radionuclides have measured

routinely in many places of the word in order to

study the description of environmental processes

such as aerosol transit and residence times in the

troposphere, aerosol deposition velocities and aerosol

trapping by ground vegetation.

MATERIAL AND METHODS.- The

sampling site is one of the environmental

radioactivity monitoring network stations operate by

the Spanish Nuclear Security Council (CSN). The

sampling point was located above the ground, on the

roof of the Faculty of Sciences, University of

Málaga. Monthly precipitation and dry fallout

samples were routinely collected using a steel tray

1m2 in area as a collecting system and polyethylene

vessels of 50 l capacity for rainwater samples

reservoirs. Measurements by gamma spectrometry

were performed to determine the 7Be and 210Pb

activities of the samples using an intrinsic REGe

detector. The peak analysis of 7Be (I= 10.52 %, 477.7

KeV) and 210Pb (I = 4%, 45 KeV) was done using

SPECTRAN AT peak analysis software. The

counting time was 172800s

RESULTS The results from depositions of 7Be

and 210Pb were correlated with four parameters:

rainfall amount, rainfall duration, number of dry days

and number of wet days. Table 1 provides the

correlation coefficients between the fluxes of and the

mentioned parameters.

Table 1. Linear correlations coefficients between

fluxes of 7Be and 210Pb and some parameters

7Be 210Pb

r p r p

Rainfall

amount

0.80 99

0.70

99

Rainfall

duration

0.44 99

0.36

95

Number of

dry days

-0.72 99 -

0.68

99

Number of

wet days

0.74 99

0.71

99

.

The depositions of 7Be and 210Pb were well correlated

with the amount of rainfall . Such relations have been

commonly observed and explained by the fact that

rainfall constitutes the major depositional pathway of

these radionuclides. As previously observed,

correlation of rainfall with 7Be seems better than

with 210Pb (Caillet el al., 2001) likely due to a

relatively greater contribution of 210Pb from dry

deposition.

The fluxes of 7Be and 210Pb are correlated one

with the other ( r = 0.83; p >99 % ) . Figure shows

the monthly results for period of measurements.

There is a relationship between air mass trajectories

and the concentrations of 210Pb and Ca ++ illustrates

the common continental origin of these elements.

common continental origin of these elements.

Caillet, S., P. Arpagaus, F. Monna and J. Dominik

(2001). Factors controlling 7Be and 210Pb

atmospheric deposition as revealed by sampling

individual rain events in the region of Geneva,

Switzerland.J. Environ. Radioactivity 53, 241-256.

0

50

100

150

200

250

300

350

400

450

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41

Meses

Flu

jo d

epo

sici

on

al 7

Be

(Bq

/m2m

es)

0

5

10

15

20

25

30

35

40

45

Depositional fluxes 7Be (Bq/m

2month)

Depositional fluxes 210Pb (Bq/m

2month)

Months

Be-7

Pb-210


DEPOSITION VELOCITIES AND WASHOUT RATIOS ON A COASTAL SITE CALCULATED

FROM GROSS ALPHA AND GROSS BETA MEASUREMENTS

C. Dueñas, M.C. Fernández, E. Gordo, S. Cañete, and M. Pérez

Department of Applied Physics I, Faculty of Sciences, University of Málaga. 29071 Málaga (SPAIN)

E-mail: [email protected]

Keywords: atmospheric aerosol, deposition velocity, precipitation, washout ratio

INTRODUCTION-The gross-alpha and gross

beta activities in aerosols and bulk deposition

samples were measured in Málaga, Southeastern

Spain (36º43´40´´N; 4º28´8´´W). At the same

sampling point, aerosols were colleted weekly

on filters and monthly precipitation sampling

was carried out to study depositions. Levels of

particulate matter fraction were also

monitorized in Málaga. Using the gross alpha

and beta activities in air and their depositional

fluxes, the deposition velocities of aerosols and

washout ratios are calculated .The minimum and

maximum value of alpha and beta deposition

velocities are 0.42 - 7.69 cms-1 and 0.09 - 2,12

cms-1 respectively and the corresponding

washout ratios are 449-6980 and 93-3760

respectively.

MATERIAL AND METHODS

The gross alpha activity was measured by a

solid ZnS (Ag) scintillation counter. The gross

beta activity was measured with a gas flow

proportional counter of the low-background

multiple detector type with four sample

detectors (Camberra HT-1000) and PM10

concentrations were measured for the beta

attenuation method.

RESULTS AND DISCUSSION The dates used

in the analysis are means monthly values of

concentrations in surface air. The period of

measurements was performed from October

2005 to September 2007. The dates were

analyzed to derive the statistical estimates

characterizing the distribution. Studies of the

frequency distribution show lognormal

distribution is significant at the 0.01 level

assuming these types of distribution, the

geometric mean should be used to characterize

average values.

Table1 provides the statistical parameters from

the measurements of alpha and beta deposition

velocities (Vdα and Vdβ) of aerosols and washout

ratios(WRα and WRβ).

Table1. Statistical parameters.

Table 2 shows the correlation coefficients and

associated probabilities between and some

parameters. Since the p-values are less that 0.01,

there is statistically significant relationship

between deposition velocities of gross alpha and

gross beta activities and the rainfall.

The maximum value of deposition velocities

alpha and beta correspond with maximum value

of rainfall

Table2. Linear correlations coefficients of Vd and

some parameters.

Figure 1 shows the negative correlation of

rainfall with the variations of washout ratios

alpha and beta. In the figure 2 is reflected in a

positive correlation of alpha and beta washout

ratios with PM10. The maximum washout ratios

values of alpha and beta correspond with a

minimum value of rainfall and an increase of

the PM10.

0,00E+00

1,00E+03

2,00E+03

3,00E+03

4,00E+03

5,00E+03

6,00E+03

7,00E+03

8,00E+03

oct-0

5

dec-0

5

feb-0

6

apr-0

6

jun-06

aug-

06

oct-0

6

dec-0

6

feb-0

7

apr-0

7

jun-07

aug-

07

0

20

40

60

80

100

120

140

160

WR alfa WR beta Rainfall

Fig.1, Variations in WR with rainfall.

0,00E+00

1,00E+03

2,00E+03

3,00E+03

4,00E+03

5,00E+03

6,00E+03

7,00E+03

8,00E+03

oct-0

5

dec-0

5

feb-0

6

apr-0

6

jun-06

aug-

06

oct-0

6

dec-0

6

feb-0

7

apr-0

7

jun-07

aug-

07

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

WR alfa WR beta PM10

Fig.2 Variations in WR with PM-10.

REFERENCES-.MCNEARY, D. and

BASKARAN, M. Depositional characteristics

of 7Be and 210Pb in southeastern Michigan. J.

Geophys. Res. 108, D7, 4210-4225, 2003.

Variable Vdα

(cm/s)

Vdβ

(cm/s)

WRα WRβ

Geometric

mean

1,26 0,48 2004,6 788,2

Dispersion

factor

2,26 2,29 2,24 2,63

Parameters Vd α (cm/s) Vd β (cm/s)

Rainfall 0.76( 0.01) 0.67( 0.01)

PM10 -0.31(0.10) -0.38(0.10)


Assesment of air mass transport of Chernobyl originated radionuclides using clustering approach

G. Lujanienė1, S. Byčenkienė2, V. Aninkevičius3

1Nuclear and Environmental Radioactivity Research Laboratory, Institute of Physics, Savanorių 231, LT-02300 Vilnius, Lithuania

2Environmental Physics and Chemistry Laboratory, Institute of Physics, Savanorių 231, LT-02300 Vilnius, Lithuania

3Semiconductor Physics Institute, A. Goštauto 11, LT-01108 Vilnius, Lithuania

Keywords: radioactive particles, water soluble compounds, air mass backward trajectories, clustering.

The Chernobyl accident caused the release of a great amount of radioactive substances into the atmosphere. Variations in ratio, concentrations and speciation of radionuclides observed after the accident were explained by different proportion of condensed and fuel particles in the Chernobyl fallout. The radioactive aerosols were detected at many locations in Europe more than 1000 km away from the source. Consequences of the Chernobyl accident have been intensively studied in the last two decades. Low activities of the Chernobyl originated radionuclides that are still present in the environment can be used to study the long distance transport of contaminants. In order to evaluate the contribution of the transport of air masses to the 137Cs air activity concentration, the time series of 137Cs variation in aerosol samples from 1993 to 1999 and 2005-2006 were analysed. The three-dimensional 10-day air mass backward trajectory method was applied to determine possible transport pathways of 137Cs. The relevant air masses were identified by using a filter and Ward’s hierarchical clustering algorithm in combination with Euclidean distance (Ward, 1963) was performed on air mass backward trajectories. In this paper, we focus on the study domain, which covers the 30 km Chernobyl zone. The 10-day air mass backward trajectories were clustered and grouped according to season, travelled way, and height over the surface before arrival. The analysis of air mass pathway has indicated the transport of 137Cs from the Chernobyl restricted zone and surrounding areas. A positive correlation was found between the frequency of air masses and the activity concentrations of 137Cs during study periods (1997-1999 and 2005-2006). The release of plutonium isotopes into the environment after the Chernobyl accident was insignificant: mean (0.224) and median (0.204) 240Pu/239Pu ratio values determined in 1995-2003 were close to those of the global fallout (Lujanienė et al., 2009). The exponential decrease in the 240Pu/239Pu atom ratio from 0.40 to 0.19 was observed (Fig. 1). It can be interpreted as a result of decrease in the amount of the Chernobyl originated plutonium in the environment due to deposition and mixing with

plutonium isotopes derived from the global fallout. The mean and median data were fitted by the first order kinetic equation and the residence time of the Chernobyl derived plutonium in the environment was obtained to be about 1.6 -0.4 years.

0 1 2 24 36 48 60 72 84 9 6 10 8 12 0

0.10

0.15

0.20

0.25

0.30

0.35

0.40

24

0 Pu/23

9 Pu a

tom

ratio

20032001199919971995Year

Figure 1. 240Pu/239Pu atom ratio in aerosol samples.

The activity concentrations of plutonium measured in monthly aerosol samples could not be traced back via backward trajectories precisely, however, its transport from contaminated territories can be expected. The comparative correlation analyses of mean monthly and daily activity concentrations of 137Cs as well as 240Pu/239Pu atom ratio with the frequency of air masses was performed in order to approximately estimate the possible transport of the Chernobyl originated plutonium. Preliminary results indicated the identical correlation for the 137Cs mean monthly activity concentrations in comparison with daily ones, while no positive correlation for the plutonium transport from the highly contaminated after the Chernobyl accident region was found in 1997-1999. Data analyses are in progress. Ward, J. H., (1963). Hierarchical Grouping to

Optimize an Objective Function. Journal of the American Statistical Association, 58, 236-244.

Lujanienė, G., et al. (2009) J. of Environ. Radioactivity, 100, 108-119.


Monitoring of 7Be and heavy metals at the Basic Environmental Observatory “MOUSSALA”

I.Penev, J.Stamenov, M.Drenska, B.Damyanov and Ch.Angelov

Institute for Nuclear Research and Nuclear Energy,

Bulgarian Academy of Sciences, 72 Tscarigradsko shosse, 1784, Sofia, Bulgaria

Keywords: aerosol sampling, radioactive particles, natural radioactivity, man-made radioactivity. The Basic Environmental Observatory is situated in the vicinity of peak of Moussala, 2971m., the highest point in Balkanian Peninsula. The peak is in the frame of reserve Central Rila, part of the National Park Rila. The observatory has been established by Institute for Nuclear Research and Nuclear Energy of Bulgaria Academy of Sciences. Here, in spite of very harsh conditions a wide spectrum of physical investigations are in full progress – meteo, atmosphere investigations, precipitations, monitoring of space and Earth radiations, different components of cosmic particles and etc., see http://beo-db.inrne.bas.bg/moussala/

A big sampler with capacity 1500-1800m3/h has been mounted according to the program of aerosols investigations on BEO-“Moussala”.The sampler is shown on figure 1.

Figure 1 Basic Environmental Observatory, on the roof is house for sampling

The air, ~ 15000m3, is passing through fibber filter with high efficiency. After sampling the filter is pressed to the pill size: diameter 56mm and thickness 13-15mm. The pills are measured by H.P.Ge spectrometer with 30% relative efficiency. More detail description of the device and method are given in Uzunov at al., 2007 and Penev at al., 2007. For 2008 more then 160 samples were analyzed for natural and man made radioactivity. Special attention is paid to the behavior of the 7Be and heavy metals isotopes. The fluctuation of the volume concentration of these isotopes is informative in exchange for the big air mass between different atmosphere strata.

The interval of the above mentioned fluctuations of 7Be at the altitude ~3000m vary in size more then 15 times, see figure 2.

0

1

2

3

4

5

6

7

8

14.1

2.20

08

12.0

7.20

08

08.0

1.20

08

05.0

6.20

07

7 Be

Act

ivity

on

the

Mus

ala

mB

/m3

01.1

2.20

06

Figure 2. The data 7Be for 2007-2008y at BEO-Moussala The intensive interchange of very big air mass at Moussala, (wind velocity is in the frame 5 –50m/s) with aerosols with different origin, together with big sampling is a splendid opportunity to control the air quality. The minimal detectable activity of the method is from 105 to 106 times lower, and then max permissible according to the IAAE standards for man-made radioactivity.

It is planned to make an analysis of the aerosols for heavy metals and other elements in the near future. Remoteness of BEO from all kind urban activity gives good opportunity for such investigations.

Some correlations between 7Be and cosmic rays including neutron component is under progress.

This work is done in the frame of BEOBAL EU project.

Uzunov, N., Janminchev, V., Penev, I., Drenska, M.,

Damyanov, B., Damyanova, A. (2007). in Annual of Constantin Preslavski University, Shumen vol.XVII B2

Penev, I., Stamenov, J., Drenska M., Damyanov, B.,

Valova, Tsc., Uzunov, N., Arhangelova, N. (2007), Ecology and Future, v.VI, n.3, 27-31.


http://beo-db.inrne.bas.bg/moussala/

Key issues in radionuclide labeled aerosol monitoring for resuspension studies and short to long-term post-accident characterizations

O. Masson1, D. Piga1, L. Bourcier2

1 Institute of Radioprotection and Nuclear Safety, IRSN-Cadarache, 13115 Saint Paul lez Durance, France 2 Laboratory of Physical Meteorology (LaMP), Blaise Pascal University, 24 Ave des Landais, 63177 Aubière, France

Keywords: Radioactive aerosol, PM10, resuspension, biomass burning, Saharan dust

The French radioactive aerosol monitoring network (OPERA) celebrates its fiftieth anniversary this year. This monitoring was gradually updated both in terms of aerosol sampling (up to 700 m3/h) and radioactivity measurement in order to determine current airborne levels as low as 0,2 µBq/m3 for 137Cs. One of the key issues in monitoring is linked to understanding the environmental transfer processes. These processes affect radioactive aerosols inside the atmospheric compartment (rainout, washout, dry deposition and impaction). Radioactive aerosol are also emitted from others compartments of the biosphere that received radionuclide fallout (via resuspension or biomass burnings). The least soil particle resuspension that has 137Cs concentration of some hundreds to tens thousands Bq/m2 (like in France) is enough to increase airborne levels temporarily. This is especially true during Saharan dust events because of high dust flux, even if the Saharan soil particle activity is lower. About a dozen Saharan events are count every year especially in the southern half of France. During Saharan dust outbreaks the daily airborne activity levels is correlated with PM10 evolution (fig. 1). Moreover the activity levels in deposited dust collected in France are quite concentrated when compared to the Saharan soils. This enrichment is due to the coarse particule segregation loss that have less affinity with 137Cs than fine particles. Our findings show that yearly averaged activity levels are twice to ten times higher for altitude locations (mountainous). The cruising altitude of Saharan plumes is responsible of this.

y = 0,015x + 1,151

R2 = 0,7527

y = 0,0323x + 0,1438

R2 = 0,755

0

1

2

3

4

5

0 50 100 150 200

Daily average PM 10 (µg.m -3)

Dai

ly a

vera

ge

137 C

s (µ

Bq.

m-3

)

Fig.1: Relationship between 137Cs activity level and

PM10 of mineral origin from Sahara

Fires also lead to redistribution of formerly deposited radionuclides, mainly due to the burning of radionuclide-enriched forest litter even over long distances. During winter, temperature inversion in the lower atmospheric layers coupled with wood burning for domestic purposes may also lead to temporary increases in airborne artificial radionuclide levels. Except for these extreme events, routine and local resuspension, regular in time and mainly dependant on season also contributes to the background level. Local resuspension effect can also be found in the better relationship with 137Cs airborne activity when considering coarse particles (PM10) that don’t travel far from their emission area, instead of fine particles (PM2.5). In France a six year long study shows that oceanic air flux is correlated to a light positive longitudinal airborne activity gradient from west to east whereas there is no background PM10

gradient (15 µg.m-3). Thus, the activity gradient can be explained by the soil activity related to the longitudinal Chernobyl fallout distribution. During eastern winds a remote contribution is added from areas more impacted by Chernobyl fallout. This added contribution results in quite the same averaged gradient but with 3 times more pronounced values at both France boundaries and a 4 times enhanced variability. At the scale of France and for the last 8 years, local and remote resuspension can explain about 1/3 of 137Cs rising levels; biomass burnings 1/3 too. The last third corresponds to winter temperature inversion coupled with domestic wood burning emissions. Enhancing knowledge about these mechanisms is useful to mapping territorial radioecological sensitivity and to explain long term post-accident persistence of airborne radionuclides at trace levels. Current needs are concerning the radionuclide aerosol size segregation.


Radiation burden of the up clearing deeply deposited radon progenies in the central airways

I. Balásházy1,2 and G. Kudela2

1Health and Environmental Physics Department, Hungarian Academy of Sciences KFKI Atomic Energy

Research Institute, Konkoly Thege M. út 29-33, 1121 Budapest, Hungary 2Aerohealth Scientific Research Development and Servicing Ltd., 2090 Remeteszőlős, Csillag sétány 7, Hungary

Keywords: radon decay products, health effects of aerosols, lung deposition, Monte Carlo simulations, clearance

Most of the lung cancers of former uranium

miners developed in the large central airways and near 90% of the neoplastic lesions have been found in airway generations 2-5. Current computational fluid dynamics calculations indicate high primary deposition density values in the peaks of the central airways. However, the cellular burden of the radon progenies deposited in the deep regions of the bronchial and acinar sections of the lung and clears up by the mucociliary escalator may contribute to the health effects found in airway generations 2-5. The surface of the airways highly increases and the deposition efficiency does not decrease remarkably with generation number, thus, it looks a reasonable supposition that the dose contribution of the up clearing radon progenies may contribute to the health effects in the large airways.

In the present work, the primary deposition distributions of inhaled radon progenies were computed in the whole respiratory system by the stochastic lung deposition model at different breathing conditions. In addition, a new bronchial clearance model has been elaborated to simulate the up cleared fractions of attached and unattached radon progenies in each of the bronchial airway generations. Finally, the ratio of the up cleared and primarily deposited fractions has been calculated at airway generation level at two different breathing patterns and at two mucus velocities.

The main input data of the clearance model are the deposition data, the velocity of the mucus in a generation, the length of the airways and the half life of radon progenies.

Based on the results, in the central airways, the radiation burden of the up clearing, more deeply deposited, radon progenies can be significantly higher than the burden of the primarily deposited fraction in these airways both at resting and light physical activity breathing conditions in case of unattached and attached radon progenies. The dose contribution of the deeply deposited 218Po and 214Pb isotopes in the large airways are higher than that of 214Bi. The radiation burden of the more deeply deposited 214Po in the central airways is practically zero because of its short half life. The results demonstrate that one of the reasons of radon induced lung cancer may be the dose contributions,

in the central airways, of the up clearing, more deeply deposited, radon progenies.

The computed deposition distributions of inhaled particles in bronchial airways have been validated by A. Kerekes et al. (2009).

0 5 10 15 200

2

4

6

8

10

12

Unattached 218Po

primary deposited fraction up cleared fraction with 15 mm/min up cleared fraction with 5.5 mm/min

Dep

osite

d an

d cl

eare

d up

frac

tions

(%)

Airway generation number

Figure 1. Primary deposition fractions of unattached 218Po at light physical activity breathing

condition and cleared up fractions at 15 and 5.5 mm/min mucus velocities.

0 5 10 15 200.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Attached 218Po

primary deposited fraction up cleared fraction with 15 mm/min up cleared fraction with 5.5 mm/min

Dep

osite

d an

d cl

eare

d up

frac

tions

(%)

Airway generation number

Figure 2. Primary deposition fractions of attached 218Po at light physical activity breathing condition

and cleared up fractions at 15 and 5.5 mm/min mucus velocities.

This research was supported by the K61193 OTKA Hungarian Project and the EUREKA OMFB-445/2007, -442/2007 Projects. A. Kerekes, A. Nagy and A. Czitrovszky (2009) Experimental flow and deposition studies with hollow bronchial airway models. 17th ISAM Congress 2009, Montery, California, USA. May 10-14 2009.


Airway deposition and health effects of inhaled radon progenies

I. Balásházy, Á. Farkas and I. Szőke Health and Environmental Physics Department, Hungarian Academy of Sciences KFKI Atomic Energy Research

Institute, Konkoly Thege M. út 29-33, 1121 Budapest, Hungary

Keywords: radon decay products, health effects of aerosols, lung deposition, CFD, deposition efficiency

Inhaled radon progenies provide more than

the half of natural radiation exposure. There is increasing evidence that the cellular distribution of radiation burden is an important factor regarding the biological response to ionisation radiation, thus, one of our tasks was the characterisation of the distribution of cellular exposure.

Histological studies of former uranium miners presented strong correlation between primer deposition hot spots and neoplastic lesions. Most of these lesions were located along the carinal regions of the large bronchial airways. In the present work, computational fluid dynamics (CFD) approaches have been applied to simulate the deposition distribution of inhaled radon progenies along central human airways. The geometry and the cellular structure of epithelial lung tissue were numerically reconstructed based on anatomical and histological data. Single and multiple alpha-hit and cellular dose distributions have been computed applying Monte Carlo modelling techniques at different breathing conditions.

Figure 1. Deposition enhancement factor (EF) distribution of attached, 200 nm, and unattached, 1 nm, diameter inhaled radon progenies on a central airway bifurcation in airway generations 4-5 during

light physical activity breathing condition. Size of scanning surface element is a 45µm side triangle.

Values of local per average deposition densities, that is, enhancement factors (Figure 1), hit probabilities (Figure 2) and doses may be up to two-three orders of magnitude higher in the deposition hot spots than the average values. Dose calculations revealed that some cell clusters may receive high doses even at low exposure conditions.

Applying the model to different radiation exposure conditions useful relations can be received regarding the linear-nonthreshold hypothesis.

Ultrafine deposition distributions can be experimentally validated by the measurement technique of Jani et al. 1999.

Figure 2. Distribution of cell nuclei hit with alpha particles in the epithelium of airway generations 1-5, leading to the right upper lobe. This research was supported by the K61193 OTKA Hungarian Project and the EUREKA OMFB-445/2007, -442/2007 Projects. Jani P., Nagy A., & Czitrovszky A. (1999). SPIE Vol. 3749, 458-459.

dp = 1 nm

EFmax = 1290

Q = 60 l/minEFmin = 0

dp = 200 nm

Q = 60 l/min

EFmax = 1400

EFmin = 0

107 inhaled radon progenies, New-Mexico

Uranium mine


Parametric study of the ionizer induced Thoron progeny concentration depletion

M. Joshi, P. Kothalkar, A. Khan, R. Mishra, B.K. Sapra and Y.S. Mayya Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Mumbai – 400085. India

Keywords: radon decay products, unattached fraction, deposition velocity, ionizer

It is well known that the negative ions emitted from the negative ion generator (NIG) help in charging the airborne particles, thereby removing them by electromigration in space charge-induced electric fields (Mayya et al., 2004). The NIGs have also been used to reduce activity concentration of radon/thoron decay products (Sheets and Thomson 1995). The physical arguments suggest different reasons for the activity reduction namely; 1) direct plate-out of freshly formed, charged fine fraction of progeny through drift in the electric field and 2) removal of the coarse fraction, thereby increasing the highly mobile fine fraction and its consequent plate-out. To investigate these aspects, measurements of various parameters like activity concentrations, deposition velocity, aerosol number concentration and the unattached fraction in presence of NIG; a systematic study has been carried out in a room environment wherein a thorium nitrate powder was placed as a source of thoron progeny. The overall decrease in the progeny concentration with NIG is depicted in Fig. 1.

0 20 40 60 80 100 120 140

10

20

30

40

50

60

70

80

Prog

eny

Con

cent

ratio

n (B

q/m

3 )

Time since ionizer on (min)

Figure 1: The decrease in the progeny concentration with the ionizer switched on.

Deposition velocity of the progeny was

measured using passive direct progeny sensors, which are deposition based absorber mounted LR115 detectors. It was observed that the deposition velocity increased from ~0.06 mh-1 to 0.3 mh-1 in presence of negative ions. The unattached fraction, estimated by wire-mesh and filter-paper sampling followed by Alpha counting, was also found to increase from 2% to 6.5%. Additionally, the activity deposited in the vicinity of the needles of the NIG showed negligible increase with NIG switched on. All these

observations strongly point at the possibility of argument (2) cited above as the mechanism of activity reduction.

The particle concentration, measured using GRIMM 5.403 Scanning Mobility Particle Sizer (SMPS) in the size range of 9.8 nm to 875 nm, showed a 3-fold decrease after switching on the ionizer. The attachment rate, X, of the progeny to the ambient aerosols (concentration, Z /cc) can be estimated using the relationship: X= β(d)Z, where β(d) is the size dependent attachment coefficient (cc/s). This is plotted in Fig. 2 and a decrease in the attachment rate is seen when the ionizer is switched on. Also, the activity median diameter was found to shift to larger sizes (94 nm to 150 nm). The lowered attachment rate also points at the increase in the unattached fraction as observed by wire-mesh filter paper sampling techniques. However, the implication of the reduction in activity concentration might not necessarily lead to a reduction in the lung dose and this requires a careful investigation.

10 100

0.0

2.0x10-4

4.0x10-4

6.0x10-4

8.0x10-4

Overall Attachment rate with NIG=22.53/h

Atta

chm

ent r

ate

(s-1)

Particle dia (nm)

Overall Attachment rate without NIG=60.3/h

Figure 2: Effect of ionizer on the attachment rate

under ambient aerosol conditions

References: Sheets R. W. and Thompson C.C. (1995), J. Radioanalytical and nuclear chemistry, 193,301-308. Mayya Y.S., Sapra B.K., Khan Arshad, Faby Sunny (2004), J Aerosol Sci.,35, 923-941. Mishra R., Mayya Y.S., Kushwaha H.S. (2009), J. Aerosol Sci. , 40, 1-15. Cheng Y.S. and Yeh H.C. (1980), J Aerosol Sci., 11, 313-320.


Determination of loss factors of aerosol particles in the sampling systems of nuclear power plants

R.F.W.Jonas1 and G.F.Lindenthal2

1TÜV Nord SysTec GmbH & Co. KG, Große Bahnstr. 31, D-22525 Hamburg , Germany, 2Ingenieurbüro für Partikeltechnologie und Umweltmesstechnik, Steinweg 8, D-34314 Espenau Germany

Aerosol measurement, particle deposition, radioactive particles, nuclear sampling systems

According to the German nuclear technical rule KTA 1503.1 the sampling system of a nuclear power plant must be able to collect aerosols with aerodynamic diameters between 0.1 μm and 20 μm with pipe retention factors below 3. As with all measured quantities the stack emission of radioactive material of a nuclear power plant with exhaust air includes an uncertainty. This is caused by the statistical error and additionally by the non-representative sampling and the deposition of aerosols in the sampling systems. The non-representative sampling results from the insufficient mixing of the air (inhomogenous concentration) and from the non-isokinetic flow in reaching the inlet of the screen of the sampling system. The deposition depends on the particle diameter and is caused by molecular diffusion, impaction and sedimentation. The ratio of the mass concentrations in front of the screen and at the end of the sampling system is called the pipe retention factor. Pipe retention factors and loss factors (without consideration of non representative sampling) are investigated for sampling systems of different nuclear power plants in Germany using three methods of determination:

1) Dispersing of test aerosols directly into probes of the screen of the sampling system and comparing the aerosol concentrations with those at the end of the sampling system

2) Generation of a defined quantity of aerosol particles at the bottom of the chimney and measuring the particle concentrations by using aerosol collectors or aerosol monitors at the end of the sampling system

3) Measuring the size distribution by number of the ambient aerosol in the chimney in front of the screen and at the end of the sampling system with optical particle counters.

The experimental results are in compliance with theoretical estimations. The measured loss factors and pipe retention factors lie below 3. The transfer properties of the sampling systems for larger particles (aerodynamic diameters up to 3 mm) also have been investigated. The results show that the sampling systems are suitable even in these cases. The presentation gives a survey of the measured pipe retention factors. The results of the three methods of determination are compared indicating advantages and disadvantages based on our experiences.


The solubility and leaching of aerosol particles – radionuclide carriers – collected on filters in the ventilation system of the Ignalina Nuclear Power Plant

R. Jasiulionis and A. Rožkov

Ignalina radioecological monitoring station, Institute of Physics, LT-02300 Vilnius, Lithuania

Keywords aerosol-surface reactions, radioactive aerosol, solubility, leaching, Ignalina NPP

Nuclear power plants are permanent emission sources of fission (137Cs, 134Cs) and activation (60Co, 54Mn) radionuclides, attached to aerosol particles, into the air.

The Ignalina Nuclear Power Plant (NPP) has two RBMK graphite-moderated channel-type 1500 MW reactors: the power generation at the Unit 1 reactor was stopped in 2005, the Unit 2 reactor is in the operation till 2010. Being formed in the active zone of the reactor, radionuclides circulate with coolant in the closed circuit and undergo physical and chemical changes on their way. Only fine hydrated ionic compounds, carriers of radionuclides, overcome the water and vapor boundary and can participate in the aerosol particle formation and growth. Relatively long-lived 137Cs (t1/2 = 30.08 year), 134Cs (t1/2 = 2.07 year), 60Co (t1/2 = 5.27 year) and 54Mn (t1/2 = 0.855 year) radionuclides, which are registered in the emissions of the stopped reactor, pass to ventilation system by longer indirect pathways. The dissolution of aerosol particles, carrier of 137Cs and 60Co, sampled on filters was studied by means of a leaching test with distilled water. Samples were collected from technological gas cleaning systems of the operating Ignalina NPP Unit 2 (before carbon adsorbers, before ventilation stack, and in the ventilations stack), in the environment in the vicinity of the Ignalina NPP and in the ventilation stack of the stopped Ignalina NPP Unit 1 in 2005-2007 (Table 1).

Table 1. Result of leaching of 137Cs and 60Co from aerosol particles sampled on filters

137Cs 60Co

C, Bq m-3 C, Bq m-3 Sampling point total unleach. W, % total unleach W, %

1 2 3 4 5 6 7 Unit 2 before adsorbers 68 23 34 ± 2 < 5 < 5 –

Before ventilation stack

0.35 0.10 29 ± 1 0.34 0.10 29 ± 6

Ventilation stack 1.69 0.44 26 ± 8 1.26 0.42 33 ± 8

Environment 3.29 2.14 65 ± 18 1.32 1.00 76 ± 22Unit 1 (stopped) ventilation stack

0.62 0.47 76 ± 10 0.64 0.51 80 ± 15

0,000001

0,00001

0,0001

0,001

0,01

0,1

1

10

100

Beforecarbon

adsorbers

Beforeventilation

stack

Ventilationstack

Environment 1 Unitventilation

stack

Act

ivity

con

cent

ratio

n, B

q/m

-3

0

10

20

30

40

50

60

70

80

90

100

Unsolubility, %

Activity concentration, Bq/m3Activity concentration of unleacheable part, Bq/m3Unsolubility,%

Figure 1. Activity concentration of 137Cs in aerosol particles, collected in operating Ignalina NPP Unit 2, in the environment in the vicinity of the Ignalina NPP and in the ventilation stack of the stopped Ignalina NPP Unit 1. Activity concentrations of 137Cs in the unleached part of aerosol particles and the unsolubility of aerosol particles are given.

The insolubility in water of radionuclides attached to aerosol particles sampled on filters, collected in the operating Unit 2 reactor effluents, is clearly lower than the insolubility in water of radionuclides attached to aerosol particles sampled on filters, collected in the ground-level air and in the effluents of the stopped Unit 1 reactor (Figure 1). Jasiulionis, R., Rožkov, A. (2008). Applied Radiation

and Isotopes, 66 (12), 1992-1998. Jasiulionis, R., Rožkov, A. (2008). European Aerosol

Conference 2008 Abstract T06A181P. Felmy, A., LeGore, V., Hartley, S. (2003). U.S.

Nuclear Regulatory Commission Report NUREG/CR-6821.


Aerosol release from Silver Indium Cadmium control rod

T. Lind1, A. Pintér Csordás2 and J. Stuckert3

1Paul Scherrer Institut, Villigen, Switzerland

2HAS KFKI Atomic Energy Research Institute, Budapest, Hungary 3Forschungszentrum Karlsruhe, Karlsruhe, Germany

Keywords: nuclear aerosols, nuclear reactor, control rod, SIC

In nuclear reactor severe accident, radioactive fission products as well as structural materials are released from the core by evaporation, and the released gases form particles by nucleation and condensation. In addition, aerosol particles may be generated by droplet formation and fragmentation of the core. In pressurized water reactors (PWR), a commonly used control rod material is silver-indium-cadmium (SIC) covered with stainless steel cladding. The control rod elements, Cd, In and Ag, have relatively low melting temperatures, and especially Cd has also a very low boiling point (about 1040 K). Therefore, control rods are likely to fail early on in the accident affecting fuel rod degradation as well as aerosol source term to the environment in the event of containment failure (Petti, 1989; Haste and Plumecocq, 2003). The QUENCH experimental program at Forschungszentrum Karlsruhe investigates phenomena associated with reflood of a degrading core under postulated severe accident conditions but where the geometry is still mainly rod-like and degradation is still at an early phase. QUENCH-13 test was the first in this program to include a SIC control rod of prototypic PWR design (Birchley et al., 2008). The effects of the control rod on degradation and reflood behaviour were examined under integral conditions, and for the first time the release of SIC aerosols following control rod rupture was measured. To characterize the extent of aerosol release during the control rod failure, aerosol particle size distribution and concentration measurements in the off-gas pipe of the QUENCH facility were carried out. The aerosol concentration and size distribution released from the core were determined using Electrical Low-Pressure Impactor (ELPI), and Berner Low-Pressure Impactors (BLPI). The sampling system was isolated from the facility before core cooling by quench. A second aerosol sampling system with 10 impactors was used also during the quench phase of the test. Two aerosol particle modes were generated, fine mode with Dae = 0.1 – 2 µm generated by vaporization and subsequent nucleation, condensation and coagulation, and coarse particle mode with Dae > 3 µm generated by droplet release and fragmentation. These findings indicate that the commonly used modeling of aerosol formation from

control rod rupture by evaporation from molten material surface would need to be refined to include aerosol generation by mechanical processes, such as droplet formation and fragment entrainment. The aerosol generation during QUENCH-13 test can be divided into five phases: 1) Transient phase: A small but steady aerosol concentration increase presumably due to release of Sn from the Zircaloy. 2) First significant aerosol release at peak bundle temperature 1560 K is thought to have been caused by a small crack in the control rod cladding. The particles contained mainly Cd as an oxide. 3) A very large, but short aerosol burst presumably due to a massive failure of the control rod contained particles rich in Cd and In, with some Ag in the fine mode particles. 4) Steady aerosol release followed the large burst at bundle peak temperature increase from 1650 to 1800 K. The particles were rich in Cd and In, and the amount of Ag increased with time. At this stage, molten control rod material was relocated downwards, and aerosol was released from molten material surface. 5) Particles released during bundle cooling by quench were mainly irregular, coarse particles containing Zr, Sn and W, along with varying amounts of Cd and In. Ag and Fe were present in some distinct particles.. The particles were presumably generated from the molten material, and by fragmentation of the Zircaloy cladding and heater elements due to thermal shocks. The authors thank Swissnuclear and Hungarian Academy of Sciences for financial support to conduct these research activities. The FZK work is sponsored by the HGF Programme NUKLEAR. Birchley, J., Austregesilo, H., Bals, C., Dubourg, R.,

Haste, T., Lamy, J.-S., Lind, T., Maliverney, B., Marchetto, C., Pinter, A., Steinbrück, M., Stuckert, J., Trambauer, K. Proc. of Nuclear Energy for New Europe, Sept. 8-11, 2008, Portoroz, Slovenia.

Haste, T., Plumecocq, W. (2003) 9th International QUENCH Workshop, FZK, Oct 13-15, 2003.

Petti, D.A. (1989) Nucl. Technol. 84, 128. Stuckert, J., Sepold, L., Grosse, M., Stegmaier, U.,

Steinbrück, M., Birchley, J., Haste, T., Lind, T., Nagy, I., Vimi, A. (2008) SARNET 4th Ann. Review Meeting, 21-25 January, 2008, Bled, Slovenia.


Experimental determination of correction factors for assessment of the activitydischarges of radionuclides bound to aerosol particles from nuclear facilities

K. Vogl1

1Federal Office of Radiation Protection, 85764 Oberschlei�heim, Germany

Keywords: Radioactive particles, emissions, particle losses, activity size distribution, representative sampling

From the stacks of nuclear facilitiesradionuclides bound to aerosol particles - besideradionuclides in gaseous form like noble gases,tritiated water vapour or C-14 containing carbondioxide – are discharged into the environment. Forthe assessment of the discharged activities of theseradionuclides a part of the effluent air stream isextracted by means of a rake of extraction probes andconducted by primary and secondary sampling tubesto the sampling devices equipped with particulatefilters. The discharged activities are calculated usingthe measured activities of the radionuclides on thedeposited particles and the measured volumes of theeffluent air stream and the air steam through theparticulate filters.

Through the following effects the activityconcentrations at the upstream side of the particulatefilters are generally lower than those in the freeeffluent air stream:– anrepresentative extraction due to uneven

distribution of air velocity and activityconcentration in the effluent air stream over thediameter of the stack;

– changes of size distribution for activity andparticle number due to anisokinetic extraction;

– losses of aerosol particles and activities of thebound radionuclides in the sampling tubes,generally due to turbulent deposition andimpaction. The losses of aerosol particles withaerodynamic diameters lager than 3 �m areconsiderable. The losses of the activities of theaerosol particle bound radionuclides depend onthe aerosol particle losses and the activity sizedistribution, which is a logarithmic standarddeviation with a geometric mean diameter ofabout 1 �m in general; the values of these lossesare in the range of some percent up to40 percent. (Vogl, 1994).

Therefore, for the assessment of the trueactivity discharges correction factors have to beused.. The so-called tube factor takes into accountonly the losses of activity in the sampling tubes andis defined as the activity concentration at the inlet ofthe extraction probes to the activity concentration atthe upstream side of the particulate filters. The so-called total correction factor considers all the abovementioned effects and is defined as the mean activityconcentration in the effluent air stream to the activityconcentration at the upstream side of the particulatefilters.

For the experimental determination of bothcorrection factors test aerosol particles may be usedwhich differ from the aerosol particles in the effluentair by being radioactive, by the chemical compositionor by a much higher mass concentration. In all casesthe activity size distribution or the mass sizedistribution of the test aerosol particle collective mustbe similar to the activity size distribution of theradionuclides carrying aerosol particles in theeffluent air stream. For most experimentaldeterminations powders like titanium dioxide aredispersed.

For the experimental determination of the tubefactor a known amount, e. g. activity or mass, ofthese test aerosol particles are injected into the inletsof the extraction probes. In case of the totalcorrection factor, these test aerosol particles areinjected into the air stream at several locationsupstream of the extraction rake.

The amount of the test particles deposited onthe particulate filter may be determined gravime-trically or by other methods, e. g. XFA.

The value of the tube factor is the ratio of theinjected amount of the test aerosol particles and theamount of the test particles on the particulate filter.The value of the total correction factor is the meanvalue of the ratios of the injected amounts of the testaerosol particles and the amounts of the test particleson the particulate filters.

For 12 investigated nuclear facilities inGermany the values of both correction factors are inthe range between 1,1 and 1,6.

Vogl, K. (1994) Aerosol particle losses in thesampling lines of nuclear facilities: Assessment andexperimental determination J. Aerosol Science,Suppl.. 1, S265 - S266


Resuspension of particles inside packages containing radioactive powders

F. Gensdarmes1, H.E. Thyebault1, J. Vendel1, B. Eckert2 and S. Fourgeaud2

1Aerosol Physics and Metrology Laboratory, IRSN, 91192, Gif-sur-Yvette, France 2 Safety Assessment Section for Transports, IRSN, 92260 Fontenay-aux-Roses, France

Keywords: aerosol generation, resuspension, powder, radioactive particle

In the field of transport of radioactive materials, the products, like UO2, PuO2 or MOX (Mixed OXyde Fuel) powders are confined in packaging which should, in normal or accidental conditions of transport, assure a leakage rate compatible with the release regulatory criteria (IAEA, 2005). The above mentioned conditions are characterized by a drop test up to respectively 1.2 m and 9 m high. In the safety demonstrations, the hypotheses usually taken into account by the French applicants are concentrations of aerosols in the cavity of the package equal to: - in normal conditions of transport: 10-3 g.m-3, - in accidental conditions of transport: 9 g.m-3 for the

first thirty minutes after the drop, and then to 0.1 g.m-3 for one week.

The current study aims at discussing the relevance of these hypotheses on the basis of a review of the most recent studies available in the literature (Curren & Bond, 1980; Sandoval et al. 1985; Barlow et al. 1995; Martens et al. 2005) on the one hand and on the other hand of new laboratory experiments with surrogate powders. The objective of these experiments is to evaluate the amount of airborne particles inside a container of powder falling on an unyielding target. Three alumina powders are used as surrogates for these laboratory experiments. The corresponding particle size distributions measured with the Coulter technique (based on the equivalent volume diameter) are presented in table 1.

Table 1. Characteristics of the particle size distributions of the alumina powders.

The container, half filled with powder, is dropped from 1 m height. The particles in suspension are sampled in real-time with an optical particle counter (OPC, Grimm 1.108) using a flexible line which is in vertical position after the drop. The total mass of aerosols is determined by weighing the OPC sampling filter. Figure 1 shows the experimental set-up. Table 2 gives the results obtained for the three powders and two bulk density (packed and non packed). The results are corrected to take into account the particles settling during the sampling period.

L = 0.5 m

ContainerØ = 130 mm,h = 275 mm,m = 3 kg,drop height: 1 m.

GRIMM1.108

Measurement of shock acceleration

l = 0

.5m

Flexible sampling line

Filtered air entry

cable for drop guide

L = 0.5 m

ContainerØ = 130 mm,h = 275 mm,m = 3 kg,drop height: 1 m.

GRIMM1.108GRIMM1.108

Measurement of shock acceleration

l = 0

.5m

Flexible sampling line

Filtered air entry

cable for drop guide

Figure 1. Experimental set-up.

Table 2. Characteristics of the airborne particles after

the shock of the container filled with different powders.

The results obtained show the effects of the particle size distribution and of the powder bulk density on the particles resuspension. Nevertheless, as the surrogate criterion used in this experiment was limited to the particle diameter, further experiments are necessary to evaluate, in particular, the impact on the results of the cohesive properties of the radioactive powders and of the high density of plutonium or uranium oxide particles. IAEA (2005). Regulations for the Safe Transport of

Radioactive Material, 2005 Edition Safety Requirements. Safety Standards Series No. TS-R-1.

Curren, W.D. and Bond, R.D. (1980). Proc. 6th Int. Symp. on Packaging and Transportation of Radioactive Material: West Berlin, nov 10-14.

Martens, R., Lange, F., Koch, W. and Nolte, O. (2005). Forum EUROSAFE, Brussels, nov 7-8.

Barlow S.V., Donelan P., Tso C.F. (1995). Proc. 9th Int. Symp. on Packaging and Transportation of Radioactive Material. Las Vegas, dec 3-8.

Sandoval R.P., Apple M.A., Grandjean N.R. (1985). Sandia National Laboratories Report : SAND-84-2645;TTC-0537- 1985 May 01.

Powders Mass median diameter (µm)

Geometric standard deviation

G1 4.6 1.4 G2 17 1.3 G3 27 1.5

Powder Airborne

particles mass (mg)

Initial aerosol concentration

(g.m-3) G1 non packed 20.3 8.07 G1 packed 12.4 4.05 G2 non packed 2.90 1.03 G2 packed 0.30 0.10 G3 non packed 0.78 0.26 G3 packed 0.18 0.06


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