Low-background environmentalactivitiesat IRSN

Low-background environmental activities atIRSN

SurveillanceRadioecologyDosimetryand other things

R. GurriaranIRSN/DEI/STEME/LMRE

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1.The IRSN

2.The need for low background measurements

3.Actual use of LSM measurementsSome examples

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ASN

French Authority

French Nuclear Establishment

IRSN

Independent Expert body

EDF, CEA, AREVA…

Nuclear facilities

Decisions (opening, closure…)

Expertise

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General director

Reactor Safety Division

Plants, Laboratories, Transports and Waste Safety Division

Nuclear defence Expertise Division

Major Accident Prevention Division

Radiological Protection and Human Health Division

Environment and Emergency

Operations Division

Institute for Radiological Protection and Nuclear Safety

~1600 persons involved in all the aspects of nuclear safety

~70 PhD students

Quantification, monitoring and interpretationof radioactivity in the environment ;

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Environmental levels

…or the continuous need for improvement

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Russian and american tests1960 to 1963

17 juin 1967 à 14 octobre 1970

17 juin 1974

17 novembre 1976

16 octobre 1980

Chinese tests

Algesiras

Saclay

137Cs in the atmosphere

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Other radionuclides in the atmosphere(Orsay)

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Environmental levelsFucus serratus -seaweed- English Channel

0,1

1

10

100

1000

10000

02/01/1983 01/01/1985 02/01/1987 01/01/1989 02/01/1991 01/01/1993 02/01/1995 01/01/1997 02/01/1999 01/01/2001 02/01/2003 01/01/2005 02/01/2007

Sampling date

Act

ivity

[Bq.

kg-1

dry

wei

ght]

60Co 40K 137Cs 241Am 154Eu 106Rh 60Co 40K 137Cs 106Rh 241Am

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• Aims : Radioecological studies, understand and forecast the behaviour of released radionuclides in normal or incidental operation

• Detection limits are not good enough to validate the models

• Need to continuously improve the measurementmethods

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Standard detectors @ Orsay

•Shielded room, 50% relative efficiency•3 m concrete overhead (~ 10mwe)

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Special and low background detectors @ Orsay

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Ultra low background detectors @ LSM

Le laboratoire est situé à 1700 m sous la pointe du Fréjus au milieu du tunnel routier

- 50% coaxial N-type

-Well type 860 cm3

-Well type 450 cm3

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Detector Backgrounds

1

10

100

1000

10000

30 230 430 630 830 1030 1230

E [keV]

Cou

ps/c

anal

a)

b)

c)

d)

210Pb

214 BiPb214

511 keV

228 214BiAc

Standard

Low background

Low background+ Anti-cosmic

Ultra lowbackground

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Background count rates[cpm 30 keV-2700 keV]

Detector backgrounds

PPT

XXL

51C n

52E

64O n

64O a

51C a

56I (1 PM)

56I

50E61C

46C

59C47O55O54O

50C

68O63O61O60O

0,10

1,00

10,00

100,00

1000,00

events/m

in [20-2700 keV]

Coaxial N type BEGe

anti

cosm

ic d

evi

ce

Standard detectors under 3 m concrete -

shielded room (10 cm Lead - 1 cm Cu)

~10 mwe

Low background at

~10 mwe

3 m concrete

ultra low

background

LSM ~4800 m we

anti

-com

pto

n d

evi

ce

Replacement of detectors by a new

generation - better adapted, better

backround

Replacement of detectors by a

new generation - better

adapted, better backround

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Understand and forecast…

•Regulatory surveillance

•Aerodynamics particle sizes

•Dosimetry impact

•Chronic doses

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Knowing the radioactive backgroundpart of French regulatory surveillance

Far from nuclear facilities :

• Air • Aerosol• Rain

• Ocean and Terrestrialcompartment

• Soil• flora• fauna

• Fluvial compartment• Water

+ Papeete (Tahiti)+ La Réunion

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Evolution du césium-137 et du béryllium-7 dans les aérosols prélevés à Papeete de 1970 à juin 2000 (données décadaires)

0,01

0,1

1

10

100

1000

10000

100000

70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00

Année

Act

ivité

[µB

q.m

-3]

Césium-137

Béryllium-7

LMRE

Standard detectors

anti-cosmic Orsay, 40% of detections

Ultra low level @ LSM, ≈100% of detections

Atmospheric 137Cs and 7Be at Papeete

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Understanding the sources of radioactivity

Understand and forecast the behaviour of released radionuclidesin normal or incidental operation

•Atmospheric discharges

•Aerosol Aerodynamic sizes

Aerosol aerodynamic sizes @ AREVA La Hague

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Aerodynamic sizes @ AREVA La Hague

13 Disks from 0.059 to >10.08 µm

0.040.90.45Total

137Cs106Rh125Sb129IBq

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Environmental expertise

Camargue sand beaches

• Ambiant dose rates reaching a few µSv/h

• Natural origin (U and Th) up to 5000 Bq/kg at secular equilibrium

• Zyrcons

• Internal dosimetry questions : - i.e. inhalation

DRPH/SRBE/Laboratoire de RadioTOXicologie Expérimentale

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• Solubility of the sand in a pulmonar fluid

• Difficulty : • - extremely small samples/low radioactive

• - measurements at LSM

• Children : 1 mSv reached with 40 kg of sand

0

20

40

60

80

100

120

140

234Th 214Pb 214Bi 210Pb

Descendants de l’Uranium

% Solubilisé

0102030405060708090

228Ac 212Bi 212Pb 208Tl

% Solubilisé

Descendants du Thorium

Camargue sand beaches

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Evaluation of the 137Cs distribution in rats after chronical consumption of contaminated water (6500 Bq.l-1)

Measurement of 137Cs in the thyroid of contaminated rats, Need of LSM measuremenst

Not expected on the biokinetics models

* Activités obtenues en utilisant un détecteur Ge ultra pur, coaxial, Φ= 58.8mm ; efficacité à 1.33 Mev = 42.1%

Chronic doses

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Understanding transport phenomena

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Conclusions

• Globally, artificial radioactivity in the environment is decreasing

• Hence, need of improving the detection limits for radioecologystudies and Regulatory surveillance

• The use of underground gamma spectrometry opens a window of oportunity in several fields :

• Environment

• Biology

• Dosimetry

• Our future studies :- Measuring the radioactivty of clouds

- Understanding the accumulation of radioactivity in the first few drops of rain

- …