Occupational exposure to Radon in French treatment spa facilities

Roselyne AMÉON

Institute for Radiological Protection and Nuclear Safety (IRSN)

European ALARA Network 9th Workshop 

European ALARA Network 9th Workshop – Augsburg - Germany

Introduction

European recommendations

Workers in thermal spas

have been incorporated into French national legislation

Regulation on Workers protection

Regulation on Public protection

have included exposure to natural radiation as one of the sources to monitor in certain occupationally exposed groups

Hydrotherapy

European ALARA Network 9th Workshop – Augsburg - Germany

Public protection

2002-460 Decree relating to public protection

2002-460 Decree relating to public protection

Worker protection

2003-296 Decree relating to worker protection

2003-296 Decree relating to worker protection

25th may 2005 Order relating to work activities including NORM

25th may 2005 Order relating to work activities including NORM

Order (not published) relating to Rn exposure (underground workplaces)Order (not published) relating to Rn exposure (underground workplaces)

• public buildings

• 31 departments

• measurements in conformity with AFNOR standards

• approved organisations

• 2 action levels 400 et 1000 Bq.m-3

22th july 2004 Order relating to Rn risk management

22th july 2004 Order relating to Rn risk management

15th july 2003 Order relating to Rn competence

15th july 2003 Order relating to Rn competence

• action level 400 Bq.m-3

• action level 1 mSv.y-1

Spa facilitiesSpa facilities

French regulation on radiation protection

Spa facilitiesSpa facilities

Public + workers concerned

workers concerned

SOURCES of RADIATION EXPOSURE

in SPA FACILITIES

European ALARA Network 9th Workshop – Augsburg - Germany

Sources of radiation exposure in spa facilities

Ingestion of radioactive thermal water (patients)

Inhalation of Rn and its short lived decay products

Ambient Gamma Radiation

European ALARA Network 9th Workshop – Augsburg - Germany

Inhalation of Rn and its short lived decay products (1)

Soil underneath

Buildings materials

Rn sources in buildings

Thermal Water

spa

European ALARA Network 9th Workshop – Augsburg - Germany

Inhalation of Rn and its short lived decay products (2)

Rn sources in spa buildings

Soil underneath (texture and radioactive characteristics)

Rn entry

Radioactive thermal water

Rn contents

Degree of use

Water supply mode

Type of treatment

10 – 1 400 Bq.l-

1

non existent after treatment

maximum during treatment

directly from point of emergenceindirectly via storage reservoirs

driving forces (stack and wind effect)

characteristics of soil/indoor interfaces

accelerated release of Rn

European ALARA Network 9th Workshop – Augsburg - Germany

Injection of compressed air

Vaporization of water

Movements of patients

European ALARA Network 9th Workshop – Augsburg - Germany

Inhalation of Rn and its short lived decay products (3)

Rn sources in spa buildings

Mechanical ventilation systems

run continuously

run only during treatment application

Ventilation

stop when facility is not in operation (closed period)

treatments with specific atmospheres incompatible with any ventilation

Soil underneath

Radioactive thermal water

Rn sources in spa buildings

Soil underneath

Radioactive thermal water

Lack of ventilationold spa facilities

European ALARA Network 9th Workshop – Augsburg - Germany

Inhalation of Rn and its short lived decay products (4)

Indoor Rn concentration in Spa A Indoor Rn concentration in Spa B

Location Mean§ (Bq.m-3)

Range* (Bq.m-3)

Mean£ (Bq.m-3)

Range* (Bq.m-3)

Administration 50 856 500 – 2 800

Entrance Hall 100 879

Pools 260 25 – 250 1 310 90 – 1 940

Aerosol inhalation room 800 50 – 2000

Gas inhalation rest room 2940 250 – 4 500 1 600 – 7 500

Underwater bath-tub 200 50 – 600 1 300 500 – 3 500

Fango room 250 25 – 350

Water supply room 1 200 250 – 3 500

§ from 30/06/03 to 15/09/03 * issued from continuous measurements £ from 5/04/00 to 29/05/00

Mechanical VS

No mechanical VS

European ALARA Network 9th Workshop – Augsburg - Germany

Sources of radiation exposure in spa facilities

Inhalation of Rn and its short lived decay products

Ambient Gamma Radiation

Inhalation of Rn and its short lived decay products

Rn decay products present in indoor air

Deposits of radionuclides in the water circuit

Thermal activity (indoor Rn concentration)

Air renewal rate

Level of humidity

Water radionuclides content

Frequency of cleaning (pipes, tanks, …)

200 nSv.h-1

METROLOGICAL and METHODOLOGICAL ASPECTS

European ALARA Network 9th Workshop – Augsburg - Germany

Metrological aspects

Long term average indoor Rn concentration

integrating Rn measurements with passive devices

Measuring instruments suitable for application in warm/humid places

Variability of equilibrium factor F

SSNTD, Electret

Rn exposure in building

Rn exposure in spa building

0,1 – 0,6

Problems with bare -track detectors

European ALARA Network 9th Workshop – Augsburg - Germany

AFNOR STANDARD NF M60-771

Measurement of environnemental radioactivity : Air

Radon-222 in buildings

Methodologies for mapping and additional investigations

Methodology – Rn public exposure

with amendments to take into account the peculiarities of thermal facilities

European ALARA Network 9th Workshop – Augsburg - Germany

Determination of

Homogeneous Zone

Type

Implantation

Number

Exposure

Results

Soil/indoor interface

Ventilation

Thermal gradient

Use of water

Supply mode

Type of treatment

+

Passive detector Closed SSNTDs

Occupied HZ

1 per 200 m2 in each occupied ZH – at least 2 per building

At least 2 months between 15th sept. and 30th april

Average Rn concentration per HZ or the highest value

compared with action levels

dispensatory period (except summer period)

All occupied levels

Measu

rin

g

devic

es

European ALARA Network 9th Workshop – Augsburg - Germany

Methodology – spa workers exposure

Due to temporal variability of Rn concentration

Underestimation of Av(Rn)

during period of using water

(no ventilation)

Overestimation of Av(Rn)

when Rn accumulates during night time

(ventilation during treatment)

Conventional integrating Rn measurements

Spa workers exposed

Medical staff (doctors, bath attendants,…)

Maintenance staff

Cleaning staff

Administrative staff ???

European ALARA Network 9th Workshop – Augsburg - Germany

Methodology – spa workers exposure

Action level of 1 mSv.y-1

Personal Rn dosimeters (-track detectors) – 3 months period

Action level of 400 Bq.m-3

Personal RnDP dosimeters – 1 month period

Measurement of Rn at monitoring sites

Measurement of Rn decay products + at monitoring sites

French rules not yet well defined

European ALARA Network 9th Workshop – Augsburg - Germany

Conclusions

What kind of methodology has to be used ?

Main sources of exposure : inhalation of Rn + radiation

People exposure to natural sources of RI in French spa facilities must be managed in respect of both regulations (public and workers)

Public exposed

Action level of 400 Bq.m-3

2 different action levels (400 Bq.m-3 + 1 mSv.y-

1)

Who is exposed ?

French regulation for Public protection

Workers exposed

2 regulations (Public + Workers)

Methodology linked to AFNOR standard

2 different methodologies (Rn or Rn decay products)

European ALARA Network 9th Workshop – Augsburg - Germany

European ALARA Network 9th Workshop – Augsburg - Germany

French thermal spa

European ALARA Network 9th Workshop – Augsburg - Germany

E 1

E 3

E 2Points of Emergence

Steam rooms – thermal gallery

Inhalation rooms

Direct supply

Treatment place

Warm water tap

Treatment place

Cold water tap

Storage reservoir

Heat exchanger

Indirect supply

Thermal water supply circuit

80 % of loss

European ALARA Network 9th Workshop – Augsburg - Germany

Rn Atlas of France

Average Rn concentrations measured in dwellings

Concentrations Bq/m3

102 -181182 -297

59 -10119 -58

31 departments ranked as priority