Occupational exposure to Radon in French treatment spa

Occupational exposure to Radon in French treatment spa facilities Roselyne AMÉON Institute for Radiological Protection and Nuclear Safety (IRSN) European ALARA Network 9 th Workshop

Introduction European recommendations ü have included exposure to natural radiation as one of the sources to monitor in certain occupationally exposed groups Workers in thermal spas ü have been incorporated into French national legislation Hydrotherapy Regulation on Public protection Regulation on Workers protection European ALARA Network 9 th Workshop – Augsburg - Germany

French regulation on radiation protection Worker protection Public protection 2002 -460 Decree relating to public protection 2003 -296 Decree relating to worker protection 22 th july 2004 Order relating to Rn risk management 25 th may 2005 Order relating to work activities including NORM • public buildings • action level • 31 departments • measurements in conformity with AFNOR standards • 2 action levels 400 et 1000 Bq. m-3 1 m. Sv. y-1 Order (not published) relating to Rn exposureworkers (underground workplaces) concerned • action level 400 Bq. m-3 15 th july 2003 Order relating to Rn Public +competence workers concerned • approved organisations Spa facilities European ALARA Network 9 th Workshop – Augsburg - Germany

SOURCES of RADIATION EXPOSURE in SPA FACILITIES

Sources of radiation exposure in spa facilities ü Inhalation of Rn and its short lived decay products ü Ambient Gamma Radiation ü Ingestion of radioactive thermal water (patients) European ALARA Network 9 th Workshop – Augsburg - Germany

Inhalation of Rn and its short lived decay products (1) ü Rn sources in spa buildings Buildings materials Thermal Water Soil underneath European ALARA Network 9 th Workshop – Augsburg - Germany

Inhalation of Rn and its short lived decay products (2) ü Rn sources in spa buildings ü Soil underneath (texture and radioactive characteristics) Rn entry driving forces (stack and wind effect) characteristics of soil/indoor interfaces ü Radioactive thermal water Rn contents 10 – 1 400 Bq. l-1 Degree of use non existent after treatment maximum during treatment Water supply mode directly from point of emergence indirectly via storage reservoirs Type of treatment accelerated release of Rn European ALARA Network 9 th Workshop – Augsburg - Germany

Injection of compressed air Vaporization of water European ALARA Network 9 th Workshop – Augsburg - Germany Movements of patients

Inhalation of Rn and its short lived decay products (3) ü Rn sources in spa buildings ü Soil underneath ü Radioactive thermal water ü Ventilation ü Lack of ventilation old spa facilities treatments with specific atmospheres incompatible with any ventilation ü Mechanical ventilation systems run continuously run only during treatment application stop when facility is not in operation (closed period) European ALARA Network 9 th Workshop – Augsburg - Germany

Inhalation of Rn and its short lived decay products (4) Mechanical VS European ALARA Network 9 th Workshop – Augsburg - Germany No mechanical VS

Sources of radiation exposure in spa facilities ü Inhalation of Rn and its short lived decay products ü Ambient Gamma Radiation 200 n. Sv. h-1 ü Rn decay products present in indoor air Thermal activity (indoor Rn concentration) Air renewal rate Level of humidity ü Deposits of radionuclides in the water circuit Water radionuclides content Frequency of cleaning (pipes, tanks, …) European ALARA Network 9 th Workshop – Augsburg - Germany

METROLOGICAL and METHODOLOGICAL ASPECTS

Metrological aspects ü Rn exposure in building Long term average indoor Rn concentration integrating Rn measurements with passive devices SSNTD, Electret ü Rn exposure in spa building Measuring instruments suitable for application in warm/humid places Variability of equilibrium factor F 0, 1 – 0, 6 Problems with bare -track detectors European ALARA Network 9 th Workshop – Augsburg - Germany

Methodology – Rn public exposure AFNOR STANDARD NF M 60 -771 Measurement of environnemental radioactivity : Air Radon-222 in buildings Methodologies for mapping and additional investigations with amendments to take into account the peculiarities of thermal facilities European ALARA Network 9 th Workshop – Augsburg - Germany

Determination of Measuring devices Homogeneous Zone Soil/indoor interface + Use of water Ventilation Thermal gradient Supply mode Type of treatment Type Passive detector Closed SSNTDs Implantation Occupied HZ All occupied levels Number 1 per 200 m 2 in each occupied ZH – at least 2 per building Exposure At least 2 months between 15 th sept. and 30 th april dispensatory period (except summer period) Average Rn concentration per HZ or the highest value Results compared with action levels European ALARA Network 9 th Workshop – Augsburg - Germany

Methodology – spa workers exposure Medical staff (doctors, bath attendants, …) ü Spa workers exposed Maintenance staff Cleaning staff Administrative staff ? ? ? ü Due to temporal variability of Rn concentration Conventional integrating Rn measurements Underestimation of Av(Rn) Overestimation of Av(Rn) during period of using water when Rn accumulates during night time (no ventilation) (ventilation during treatment) European ALARA Network 9 th Workshop – Augsburg - Germany

Methodology – spa workers exposure French rules not yet well defined ü Action level of 400 Bq. m-3 Measurement of Rn at monitoring sites Personal Rn dosimeters ( -track detectors) – 3 months period ü Action level of 1 m. Sv. y-1 Measurement of Rn decay products + at monitoring sites Personal Rn. DP dosimeters – 1 month period European ALARA Network 9 th Workshop – Augsburg - Germany

Conclusions ü People exposure to natural sources of RI in French spa facilities must be managed in respect of both regulations (public and workers) ü Main sources of exposure : inhalation of Rn + radiation ü What kind of methodology has to be used ? Who is exposed ? French regulation for Public protection ü Public exposed Action level of 400 Bq. m-3 Methodology linked to AFNOR standard ü Workers exposed 2 regulations (Public + Workers) 2 different action levels (400 Bq. m-3 + 1 m. Sv. y-1) 2 different methodologies (Rn or Rn decay products) European ALARA Network 9 th Workshop – Augsburg - Germany

European ALARA Network 9 th Workshop – Augsburg - Germany

French thermal spa European ALARA Network 9 th Workshop – Augsburg - Germany

Thermal water supply circuit Direct supply Steam rooms – thermal gallery Inhalation rooms E 3 Points of Emergence Indirect supply Treatment place Warm water tap E 2 E 1 Storage reservoir Heat exchanger 80 % of loss European ALARA Network 9 th Workshop – Augsburg - Germany Treatment place Cold water tap

Rn Atlas of France Average Rn concentrations measured in dwellings Concentrations 19 -58 59 -101 Bq/m 3 102 -181 182 -297 31 departments ranked as priority European ALARA Network 9 th Workshop – Augsburg - Germany