TTK peahoone radooni ohutuse monitooring

Lõputöö uuringute käigus jõuti järeldusele, et TTK peahoone asub kõrge radooniriskiga pinnasel ja hoone ligidal asuvad fosforiiti ja graptoliitargiliiti sisaldavad kihistud, mis võivad olla TTK hoone siseõhu peamisteks radooni allikateks, kandudes TTK hoone alla lahustununa põhjavees, mööda vett mitteläbilaskvat Tiskre kihistut. TTK peahoone ruumidee sisõhu radooni kontsentatsiooni väärtuste mõõdistus tulemustest selgus, et mõõdistatud ruumid võib tavalise ventilatsiooni töötamise režiimi korral valdavalt hinnata radooniohutuks. Arvestades aga osades ruumides mõõdistatud kõrgeid radooni kontsentratsioon väärtusi, on siiski osades ruumides radoonioht olemas, mille aga lahendaks ventilatsiooni režiimi parandamine, mis hoiaks tööajal siseõhu radooni kontsentratsiooni ohutul tasemel. Tööajal ja ventilatsiooni töötamise ajal registreeritud radooni kontsentratsioonide keskmised väärtused jäid kõikidel ruumidel alla riiklikult kehtestatud viitetaset 300 Bq/m3, mis tõttu võib neid ruume hinnata ohutuks. Ruum 124a, oli aga ainuke ruum mille tööajal registreeritud radooni kontsentratsiooni mõõdetud keskmine väärtus oli 332 Bq/m3, ületades viitetaset 300 Bq/m3. Lõputöö uuringute abil tuvastati hoones radooni ebaühtlane jaotumine ja radooni vertikaal suunaline liikumine hoone kõrgematele korrustele. Avastati, et radoon liigub otse 1. korruselt 4. korrusele jättes vahele vahepealsed korrused. Sellega tõestati seda, et hoone radooniohutuse hinnanguks ei pruugi piisata maaluse ja 1. korruse radooni kontsentratsiooni mõõdistustest vaid radooni tuleks mõõdistada kõikidel korrustel kus asuvad tööruumid. Lõputöös mõõdistatud tulemuste põhjal jõuti ka veel radoonitõkke lahendusteni, milleks oleksid ventilatsioonirežiimi parandamine, hoone õhulekkete tihendamine ja radooni kogumissüsteemi paigaldamine hoonele. Arvestades TTK peahoone suurust ja tulemustest selgunud radooni ebaühtlast jaotumist hoones, oleks mõistlik korraldada täiendavad radooni kontsentratsiooni mõõdistusi seni mõõtmata jäänud ruumides, et saaks anda tervikliku ja lõpliku radooniohutuse hinnangu TTK peahoonele. Veel ka seeõttu, et välja pakkuda parimaid radoonitõkke lahendusi TTK peahoonele.

The thesis is based on European Directive 2013/59/Euratom, in connection with which Regulation 28 issued by the Ministry of the Environment 28 “Reference level of radon concentration in workplace, procedure for measurement of radon concentration in air and obligations of employers in workplaces with increased radon risk” entered into force in Estonia. The annex to the regulation contains a list of areas with an increased radon risk, including Tallinn, where the object under research within the framework of this thesis is located. In order to perform the measurements of the radon concentration of the indoor air in the rooms of the main building of the Tallinn University of Applied Sciences, the methodology of short-term continuous measurement of the guidelines “Measurement of radon activity concentration” (2016) was followed. The objectives of the thesis are to map the radon risk of the main building of Tallinn University of Technology and to measure the radon concentration in the indoor air, and also to give an assessment of the radon risk and safety of the building through the results. In addition, the goal is to spot possible sources of radon in the building of Tallinn University of Applied Sciences, to identify possible radon movements inside the building and to suggest possible suitable solutions for decreasing radon levels in the building. In the course of preparing the thesis, it was concluded that the main building of Tallinn University of Applied Sciences is located on high radon risk soil and that there are formations containing phosphorite and graptolite-argilite in the vicinity of the building, which may be the main origin of radon in the indoor air of the building of Tallinn University of Applied Sciences, transferred under the building of Tallinn University of Applied Sciences, dissolved in groundwater. The results of the measurement of the radon concentration values of the indoor air in the rooms of the main building of Tallinn University of Applied Sciences revealed that the measured rooms can be predominantly evaluated as radon-safe under normal operation of ventilation. Nevertheless, given the high radon concentration values measured in some rooms, there is a risk of radon in some of them, which would be solved by enhancing the ventilation operational regime, which would keep the indoor air radon concentration at a safe level during working hours. The research of the thesis identified the uneven distribution of radon in the building and the vertical movement of radon towards the upper floors of the building. It was found that radon moves directly from floor 1 to floor 4, skipping the intermediate floors. This proved that measurements of underground and 1 floor radon concentrations may not be sufficient for the radon safety assessment of a building, but that radon should be measured on all floors where work spaces are located. With reference to the results measured in the thesis, radon barrier solutions were also reached, which would be the improvement of the ventilation regime, the sealing of air leaks in the building and the installation of a radon collection system in the building. Considering the size of the main building of Tallinn University of Applied Sciences and the uneven distribution of radon within the building, it would be reasonable to execute additional measurements of radon concentrations in the hitherto unmeasured rooms, in order to provide a comprehensive and definitive radon safety assessment of the main building of Tallinn University of Applied Sciences. Plus, also to suggest the best radon barrier solutions for the main building of Tallinn University of Applied Sciences.