RADIOECOLOGICAL STUDY IN A COAL POWER PLANT ENVIRONMENT

THE INCREASE OF NATURAL RADIONUCLIDE CONCENTRATIONS IN THE ENVIRONMENT OF A COAL POWER PLANT (CPP) WAS EXAMINED. LIGNITES THAT ARE USED IN THE SELECTED AREA (PTOLEMAIS VALLEY) FOR THIS STUDY, CONTAIN INCREASED CONCENTRATION OF THE URANIUM SERIES RADIONUCLIDES. THE RESULTS SHOWED THAT 31%, 12%, AND 27% OF 238U, 226 RA AND 210 PB, RESPECTIVELY, ARE RELEASED IN THE ATMOSPHERE AS SMALL PARTICLES OR IN GASEOUS FORM. THE BEHAVIOUR OF THE URANIUM SERIES RADIONUCLIDES INDICATE THAT THESE NUCLIDES ARE ASSOCIATED WITH ORGANIC MATTER OF LIGNITES. ON THE CONTRARY, THE BEHAVIOUR OF 228 RA AS WELL AS OF 40K, INDICATE THAT THESE NUCLIDES ARE ASSOCIATED WITH THE MINERAL MATTER OF LIGNITES. THE MEAN ENHANCEMENT OF RADIONUCLIDE CONCENTRATIONS IN THE ATMOSPHERE IS ESTIMATED TO BE 12-47 MBQ,M-3 FOR238U AND 4-14 MBQ,M-3 FOR 226RA AT THE SITES LOCATED IN THE PLATEAU OF THE VALLEY. THE CORRESPONDING VALUES AT THE HIGH ELEVATIONS WERE INCREASED UP TO TWO ORDERS OF MAGNITUDE. (SHORTENED)Η ΕΠΙΒΑΡΥΝΣΗ ΤΟΥ ΠΕΡΙΒΑΛΛΟΝΤΟΣ ΤΩΝ ΑΤΜΟΗΛΕΚΤΡΙΚΩΝ ΣΤΑΘΜΩΝ (ΑΗΣ) ΣΕ ΡΑΔΙΕΝΕΡΓΑ ΝΟΥΚΛΙΔΙΑ ΕΞΕΤΑΣΤΗΚΕ ΣΤΗΝ ΠΑΡΟΥΣΑ ΜΕΛΕΤΗ. ΣΤΟΥΣ ΛΙΓΝΙΤΕΣ ΤΗΣ ΠΕΡΙΟΧΗΣ ΠΟΥ ΕΠΙΛΕΧΘΗΚΕ ΓΙΑ ΤΗΝ ΜΕΛΕΤΗ ΑΥΤΗ (ΚΟΙΛΑΔΑ ΤΗΣ ΠΤΟΛΕΜΑΙΔΑΣ) ΠΡΟΣΔΙΟΡΙΣΤΗΚΑΝ ΥΨΗΛΕΣ ΣΥΓΚΕΝΤΡΩΣΕΙΣ ΤΩΝ ΙΣΟΤΟΠΩΝ ΤΗΣ ΣΕΙΡΑΣ ΤΟΥ ΟΥΡΑΝΙΟΥ. ΠΟΣΟΣΤΑ 31%, 12% ΚΑΙ 27% ΤΩΝ 238U, 226RA ΚΑΙ 210ΡΒ ΑΝΤΙΣΤΟΙΧΑ ΠΟΥ ΠΕΡΙΕΧΟΝΤΑΙ ΣΤΟΥΣ ΛΙΓΝΙΤΕΣ, ΒΡΕΘΗΚΕ ΟΤΙ ΔΙΑΦΕΥΓΟΥΝ ΣΤΗΝ ΑΤΜΟΣΦΑΙΡΑ ΕΙΤΕ ΥΠΟ ΜΟΡΦΗ ΜΙΚΡΩΝ ΣΩΜΑΤΙΔΙΩΝ ΕΙΤΕ ΣΕ ΑΕΡΙΑ ΜΟΡΦΗ. Η ΣΥΜΠΕΡΙΦΟΡΑ ΤΩΝ ΙΣΟΤΟΠΩΝ ΤΗΣ ΣΕΙΡΑΣ ΤΟΥ ΟΥΡΑΝΙΟΥ ΔΕΙΧΝΕΙ ΝΑ ΥΠΑΡΧΕΙ ΣΥΝΔΕΣΗ ΤΩΝ ΙΣΟΤΟΠΩΝ ΑΥΤΩΝ ΜΕ ΤΗΝ ΟΡΓΑΝΙΚΗ ΥΛΗ ΤΩΝ ΛΙΓΝΙΤΩΝ, ΕΝΩ Η ΣΥΜΠΕΡΙΦΟΡΑ ΤΟΥ 228RA (232TH) ΩΣ ΚΑΙ ΑΥΤΗ ΤΟΥ 40Κ, ΕΔΕΙΞΕ ΝΑ ΥΠΑΡΧΕΙ ΣΥΝΔΕΣΗ ΑΥΤΩΝ ΜΕ ΤΑ ΑΔΡΑΝΗ-ΑΝΟΡΓΑΝΑ ΥΛΙΚΑ ΠΟΥ ΠΕΡΙΕΧΟΝΤΑΙ ΣΤΟΥΣ ΛΙΓΝΙΤΕΣ. Η ΜΕΣΗ ΕΤΗΣΙΑ ΑΥΞΗΣΗ ΤΩΝ ΣΥΓΚΕΝΤΡΩΣΕΩΝ ΤΩΝ ΡΑΔΙΟΝΟΥΚΛΙΔΙΩΝ ΣΤΗΝ ΑΤΜΟΣΦΑΙΡΑ ΥΠΟΛΟΓΙΖΕΤΑΙ ΟΤΙ ΕΙΝΑΙ 12-47 ΜΒQ.M-3 ΓΙΑ ΤΟ238U ΚΑΙ 4 -14ΜΒ ,Μ-3 ΓΙΑ ΤΟ 226RA ΣΤΗΝ ΒΑΣΗ ΤΗΣ ΚΟΙΛΑΔΑΣ. ΟΙ ΑΝΤΙΣΤΟΙΧΕΣ ΤΙΜΕΣ ΓΙΑ ΤΑ ΥΨΩΜΑΤΑ ΤΗΣ ΠΕΡΙΟΧΗΣ ΕΙΝΑΙ ΑΥΞΗΜΕΝΕΣ ΕΩΣ ΚΑΙ ΔΥΟ ΤΑΞΕΙΣ ΜΕΓΕΘΟΥΣ. Η ΜΕΣΗ ΣΥΓΚΕΝΤΡΩΣΗ ΤΟΥ 226RA ΣΤΗΝ ΑΤΜΟΣΦΑΙΡΑ ΕΚ ΤΩΝ ΑΕΡΙΩΝ ΤΗΣ ΚΑΥΣΗΣ ΤΩΝ ΛΙΓΝΙΤΩΝ,ΗΤΑΝ 60 ΜΒQ,M-3. (ΠΕΡΙΚΟΠΗ

Aging studies for the ATLAS monitor drift tubes using alpha particles

A systematic study of the behavior of the ATLAS monitored drift tubes (MDTs) under controlled irradiation by alpha particles has been performed. The aim of the study was two fold: to quantify the response of the tubes to alpha particles and consequence to heavily ionizing particles and to measure aging effects under the nominal operating conditions. A setup of a well controlled radium (/sup 226 /Ra) source was used in order to enrich the tube gas (Ar, CO/sub 2/) with the alpha emitter /sup 222/Rn and irradiate the tubes internally. The ionization produced by an alpha particle with mean energy of 6.4 MeV has been measured. The energy deposition of the alpha and beta rays of the source inside the tube was computed by simulating the MDT geometry and the accumulated charge to the tube wire at operating conditions was calculated. The results of aging effects up to an accumulated charge of 41.5 mC are given by using the alpha-irradiation setup. (4 refs)

Study of the performance of the ATLAS monitored drift tube chambers under the influence of heavily ionizing α\alpha-particles

The MDT chambers of the ATLAS Muon Spectrometer will operate in a heavy LHC background environment mainly from photons and neutrons. The ionization produced by neutron recoils is much higher than the one from photons or muons and can be simulated by the use of alpha particles. A systematic study of the behavior of the ATLAS Monitored Drift Tubes (MDTs) under controlled irradiation has been performed. The presence of alpha particles results in the reduction of the gas gain due to space charge effects. The gas gain reduction has been studied in a single tube set up using a well controlled radium (/sup 226/Ra) source in order to enrich the tube gas (Ar/CO/sub 2/) with the alpha emitter /sup 220/Rn and irradiate the tubes internally. The results are confronted with Garfield simulations