Radon atworkplaces in Hungary

Transcription

1 Regional Workshop on Radon inworkplaces as an Element of a National Radon Action Plan, Tallinn, Estonia, th May 2016 Radon atworkplaces in Hungary National Public Health Center (NPHC) National Research Directorate for Radiobiology and Radiohygiene (NRDRR) Zsolt Homoki

2 Content General information Legislation in Hungary Exposure of workers from radon Radon concentration in show caves, mines, mofett, SPAs Radon survey in kindergartens and crèche Radon survey in schools Reliability of short term measurements 2

3 About Hungary... Some statistical data Territory: 93,036 km 2 No. of dwellings: 4,408 millions Population: 9,958 thousands of people No. of workers: millions of people 3

4 Radon at workplaces Legislation in Hungary Year Legislation 1996 Act CXVI on Atomic Energy of 1996 The minister responsible for health is authorised to regulate in decree the acceptable level of the concentration of radon and radon daughter elements in residential and public buildings /2000 Ministry of Health decree Effective dose limit for workers: 100 msv/ 5 years (external + internal exposure). The doses of workers are controlled by the health authority (NPHMO). If it can be assumed that, the workers are exposed to radon concerning the type of job, by the assessment of the occupational exposure the doses from radon has to be also taken into account. Action level for workplaces has been established in 1000 Bq/m 3 annual average radon concentration /2015 Government decree (instead of 16/2000 MH decree) Effective dose limit for workers: 20 msv/ year. The doses of workers are controlled by the nuclear authority (HAEA). This dose limit has to be also applied for those situation, when the workers should be exposed by radon above the reference level 300 Bq/m 3 annualaverage concentration. The employers are responsible to protect their employee against all kind of health risk (involving the exposure to radon) and employers responsibility to ensure the personal dosimetry of workers. 4

5 Legislation categories for one person Years old General population > 65 retired adult Exposure situation dwelling workplace Categories inhabitant, home owner workers (employee or employer) (radiation or non-radiation) student 3-16 child public building medical examination or treatment 0-3 infant living in the ambient of an industrial facility On the other hand the same person can be a decision maker a member of the authority a radon professionals 5 general public patient endangered public a building professionals a potentially exposed people

6 Workplaces, where the level of radon can be considerable Where the main source is the natural environment Mines (uranium and other kind of ore) + following processing Show caves Mofetts (radon SPAs) Spas Others: underground workplaces (buildings) Other activities which are regard to TENORM problem where the products or waste material can contain in high concentration U-238 and Th-232 isotopes. oil refinery burning of fuel (charcoal or gas) in power plants building material production (especially clay based products, like bricks, tiles) geothermal energy production fertilizer production (agriculture industry) purification of communal wastewater purification of (drinking) water In most of these cases the disposal of the waste material or the by-product gives problem. 6

7 Personal dosimetry Categories for radiation workers: A when the dose of the workers should be exceeded the 6 msv/year B when the dose of the workers should be not exceeded the 6 msv/y The exposure of A categorised workers have to be controlled! It means wearing of personal dose meters. The personal dosimetry service is provided by the NPHC National Research Directorate for Radiobiology and Radiohygiene. Type of dose meters Before 2012 films After 2012 TLDs (CaSO 4 (Tm) + LiBO 4 ) Both of them are able to measure only the doses to beta-, gamma- radiation and X-ray! Exposure to radon There is needed additional detectors! Passive detectors are useful for personal radon dosimetry purposes. Active detectors can be used to monitor places (rooms). 7

8 Control of exposure of workers from radon 1. Uranium mines (Mecsek hill) (The mining was stopped and the mine was partly recultivated.) Based on the legislation of the General Mining Committee (1972) There were established limit for - alpha-potential energy of radon progenies: 1 WLM (= 1, MeV/l) - Ra-226 concentration in air: 1,1 mbq/m 3 (= µci/ml), - natural uranium concentration in air: 2,6 mbq/m 3 (= µci/ml). The measurements were taken at determined reference point daily or weekly and doses of the workers were calculated using the monthly average value. The annual average radon exposure of the miners for the period of Source: Public Limited Company for Radioactive Waste Managment, (András Várhegyi) Görgy Köteles et al. Citogenetic examination of uranium miners,

9 Control of exposure of workers from radon 2. Manganese mines (Úrkút) (The mining was stopped not so far away because of economical reason.) Originally the radon concentration in the mine was 2-3,000 Bq/m 3 and somewhere it could be ~ 10,000 Bq/m 3 in isolated point. After 2000 according to the actual valid legislation the radon-concentration was monitored and a ventilation system was built in to decrease the level of radon under the limit: 1000 Bq/m 3. The doses of the workers were controlled by personal dose meters. After 2014 There was need to further mitigation action to comply the new legislation (300 Bq/m 3 reference level was established). The solution was applying of personal ventilation system. 9 Source:

10 Radon and thoron concetration in Maganese mine based on the measurement of University of Pannonia 222 Rn and 220 Rn six-monthly average activity concentrationsat themanganese mine (Hungary) 1800 Radon and Thoron concentration [Bq/m 3 ] Radon Thoron Number of measurement point

11 Control of exposure of workers from radon 3. Show cave(tapolca) 2 functions: tourist visit and healing by radon. The radon concentration in the cave is about 1 20 kbq/m 3 depending on the season. Exposure of workers The tourist guider wears track etch detectors, which are evaluated monthly. Out of working time the detectors are placed in radon safe cabin near to the entrance. The annual dose of the workers are near to the dose limit (20 msv). But if it is necessary the working (residence) time of the tourist guider are restricted and more workers are employed. Earlier the radon concentration was measured by track etch detectors at several points in the cave with monthly change. And level of radon was monitored by active detectors too at more points with 1 hour resolution for 1 up to 3 years. Source: 11

12 Radon and thoron concetration in Show cave Tapolca based on the measurement of University of Pannonia 222 Rn and 220 Rn six-monthly average activity concentrationsat thehospital-and Show Cave of Tapolca(Hungary) 2500 Radon and Thoron concentration [Bq/m 3 ] Radon Thoron Number of measurement point

13 Radon concentration in show caves and mines In Hungary about 3,700 caves are recorded, and 30 show caves are opend for visitors. Caves Place Radon concentration Cave Szemlő-hegyi (Budapest) 4-8 kbq/m 3 Cave Béke (Aggtelek) ~ 8 kbq/m 3 Cave Szent István (Miskolc) ~ 0,15-1 kbq/m 3 Cave Baradla (Aggtelek) 1-2 kbq/m 3 (south-west end point) (Jósvafő) ~ 5 kbq/m 3 (north-east end point) Clay mine (Felsőpetény) Radon concentration during working time: ~ 1 kbq/m 3 out of working time: 5-15 kbq/m 3 The referred measurements were made by Academy of Hungarian Science, Instiute for Nuclear Research, Debrecen University of Pannonia, Institution for Radiochemistry and Radioecology, Veszprém collaboration with other universities and institutions The exposure of the tourist guiders and workers was measured in these caves too, but their calculated doses were below the dose limit, therefore they do not wear personal dose meters. By the calculation of the doses to radon the equilibrium factor (F eq ) has big importance to the results, but its value shows high spatial and time variation! 13

14 Show caves, which are opened for tourists Cave Baradla 14 Source:

15 Radon concentration in Mofetts 1. In Hungary two mofetts are operated: one in Mátraderecske and one in Parádfürdő. They were examined by Phd. István Csige (Hungarian Academy of Science, Debrecen). 15

16 Radon concentration in Mofetts 2. Distribution of radon concentration in Mátraderecske based on the results of István Csige. 16

17 Radon survey of kindergartens and crèche István Nikl organised a nationwide radon survey in kindergartens and in crèche in He made measurement in 302 from the total 4,466 institutions, in 364 group rooms. The sampling points placed in 206 settlements covering the whole territory of Hungary. The examination was started in January and finished in June of 1998 (6 months). Type of detectors electret (E-Perm) for radon and TLD (CaSO 4 (Tm)) for gamma-radiation The statistical results Examination Avarege value Min max value National average Radon concentration 90 Bq/m Bq/m Bq/m 3 Gamma dose rate 107 ngy/h ngy/h 127 ngy/h Radon conc. distribution 10 Bq/m 3 < 50 Bq/m 3 < 100 Bq/m 3 < 600 Bq/m 3 < 93 % 60 % 26 % 2,5 % Using these results the annual dose of the children was founded to be 0,49 msv. He calculated with 2000 h residence time (50 8 h) per year by this estimation. Source: I. Nikl, Gy. Köteles, The radon concentration, the environmental dose and the originated exposure in Hungarian kindergartens and crèche, Egészségtudomány, Vol. 44, pp ,

18 Rn-222 and Ra-226 concentration in thermal waters and SPSs Indoor radon conc. in Rudas SPA in 1994 Rn and Ra conc. in thermal waters SPAs Rn-222 Ra-226 (Bq/l) (mbq/l) Rudas SPA Juventus spring Attila spring Hungária spring Rác SPA Rác Nagy spring Lukács SPA Boltív spring Római spring Rn conc. in thermal waters and SPAs Török SPA Rn-222 Indoor radon (Bq/l) (Bq/m 3 ) Török spring Sources: Pável Szerbin, Radon in the air of Rudas SPA, Fizikai szemle, Vol. 6, pp 241 (1994) Eszter Baradács, Radon and radium content of mineral and thermal waters, Phd Thesis, Debrecen, Hungary (2002) Norber Kávási, Determination of annual average radon concentration and exposure to radiation at different workplaces, Phd Thesis, Veszprém, Hungary (2006)

19 Radon survey in schools in2007 The survey was organised by GáborKocsy (NRIRR) in Start: he send letters to the directors of the schools to ask to participate in the survey. The ratio of the positive feedback was 37 57%. A package was sent to schools containing - background information about the survey and instruction to the placement - 3 track etch detectors + 1 TLD (CaSO 4 :Tm) - questioner about the building characteristic Exposure time: 1,5 month (in Spring of 2007) Radon survey in schools started in 2015 This survey is organised by - University of Pannonia, Institution for Radiochemistry and Radioecology, Veszprém - Social Organisation for Radioecological Cleanliness, Veszprém - Szent István University, Gödöllő 99 kindergartens participate in the survey from 89 settlements (43% of total) Planned examinations - indoor radon and thoron concentration - indoor and outdoor gamma dose rate - soil gas concentration and permeability measurements - soil sampling and analyse by gamma-ray spectrometry for (Ra-226, Th-232, K-40) - radon and thoron exhalation and emanation measurements 19

20 Results of survey of schools Veszprém county Name of schools Exposure time (day) Radon conc. (Bq/m 3 ) SD (Bq/m 3 ) Gamma dose rate (nsv/h) Uncer. (nsv/h) Ajka Kossuth Lajos Általános Iskola ,5 86,2 0,1 Mikes Kelemen Általános Iskola ,9 114,6 5,6 Fekete István Általános Iskola , ,4 Eötvös Loránd Általános Iskola ,7 155,3 3 Vörösmarty Mihály Általános , Iskola és Gimnázium Balatonfőkajár Balatonfőkajár-Csajág Általános ,8 73,6 0,3 Iskola Balatonfüred Eötvös Loránd Általános Iskola ,5 85,3 1 Pápa Weöres Sándor Általános Iskola ,1 61,1 1,3 Sümeg Kisfaludy-Ramassetter Iskola ,6 89,3 1,3 Szigliget Szigligeti Közös Fenntartású ,7 99,9 4 Általános Iskola Várpalota Várkerti Általános Iskola és ,1 91,7 3,1 Szakiskola Veszprém Báthory István Általános Iskola ,7 83 0,5 Zirc Reguly Antal Általános Iskola és ,2 117,1 9,5 Előkészítő Szakiskola

21 Results of survey of schools Gamma Alföld Exposure Radon con. SD time (day) (Bq/m 3 ) (Bq/m 3 dose rate ) Name of shools (nsv/h) Kecskemét Lánchíd Utcai Általános Iskola ,0 80,5 2, ,7 86,8 0,1 Piarista Általános Iskola, Gimnázium és Diákotthon Uncer. (nsv/h) Kiskőrös Bem József Általános Iskola ,6 86,7 0,7 Kiskunhalas Fazekas Gábor Utcai Általános ,3 114,3 7,5 Iskola Kertvárosi Általános Iskola ,8 74,5 1,1 Soltvadkert Kossuth Lajos Általános Iskola ,9 111,6 2,1 és Alapfokú Művészetoktatási Intézmény Tabdi Tabdi Általános Iskola ,7 88,8 1,4 21

22 Results of survey of schools Pest county Iskola neve Exposure time (day) Radon conc. (Bq/m 3 ) SD (Bq/m 3 ) Gamma dose rate (nsv/h) Uncer. (nsv/h) Abony Somogyi Imre Általános Iskola ,4 98 2,1 Jászberény Gróf Apponyi Albert Általános ,0 89,1 2,5 Iskola és Alapfokú Művészetoktatási Intézmény Belvárosi Általános Iskola , ,4 District XII of Budapest Name of schools Exposure time (day) Radon conc. (Bq/m 3 ) SD (Bq/m 3 ) Gamma dose rate (nsv/h) Uncer. (nsv/h) Árpád Utcai Általános és Német ,0 111,6 7,6 Nemzetiségi Iskola Bartók Béla Általános Iskola ,2 93,3 4 Csillagjáró Általános Iskola ,8 80,4 6,5 Rózsakerti Általános Iskola ,0 62,9 1,6 22

23 Reliability of short term measurements After the stop of ventilation of a room the radon concentration will generally increase to a certain time and after that it remains at an equilibrium level. 1. day 2. day 3. day 106 Bq/m 3 1. day 2. day 3. day 4. day 324Bq/m 3 1. day 2. day 3. day 4. day 5. day 316 Bq/m 3 48 Bq/m 3 23

24 Thankyou foryourkindattention! 24