ABSTRACT
Since Dec 1988, date of the French-Soviet joint space mission "ARAGATZ", the CIRCE device (Compteur Intégrateur de Rayonnement Complexe dans l'Espace) had recorded dose equivalent and quality factor inside the MIR station (380-410 km, 51.5 degrees). After the initial gas filling two years ago, the low pressure tissue equivalent proportional counter is still in good working conditions. Some results of three periods, viz Dec 1988, Mar-Apr 1989 and Jan-Feb 1990 are presented. The average dose equivalent rates measured are respectively 0.6, 0.8 and 0.6 mSv/day with a quality factor equal to 1.9. Some detailed measurements show the increasing of the dose equivalent rates through the SAA and near polar horns. The real time determination of the quality factors allows to point out high LET (Linear Energy Transfer) events with quality factors in the range 10-20.
Subject(s)
Cosmic Radiation , Linear Energy Transfer , Radiation Monitoring/instrumentation , Radiation Protection/standards , Space Flight , Spacecraft/instrumentation , Atlantic Ocean , Earth, Planet , France , Radiation Dosage , South America , Time Factors , USSRABSTRACT
During the French-Soviet space mission "Aragatz," the experiment CIRCE (Compteur Integrateur de Rayonnement Complexe dans l'Espace) recorded the dose rate and quality factor values inside the MIR station. This paper presents results obtained with a new active dose equivalent meter based on microdosimetric techniques and using a low pressure tissue equivalent proportional counter. In terms of lineal energy CIRCE device works in the 0.2-1200 keV micrometer-1 range in tissue. Preliminary studies were performed in photon, neutron and heavy ion beams, and in the real stratosphere cosmic radiation field. Long term measurements on-board MIR station from December 1988 to April 1989 gave an average quality factor value equal to 1.9 +/- 0.3. Through the South Atlantic Anomaly (SAA), the quality factor was equal to 1.4. The temporal orbital variations of the dose rates and quality factors have been established in space dosimetry for the first time.
Subject(s)
Cosmic Radiation , Radiation Monitoring/instrumentation , Solar Activity , Space Flight , Spacecraft/instrumentation , Equipment Design , Linear Energy Transfer , Radiation Dosage , Radiation Monitoring/methods , Time FactorsABSTRACT
Iodide can reduce radioactive iodine thyroid uptake and whole-body irradiation. Maximal effectiveness is obtained when 3 conditions are fulfilled: adequate dosage: potassium iodide 130 mg (i.e. iodide 100 mg) as tablets in adults and older children, 50 mg in infants under one year of age; prompt administration after contamination and daily treatment as long as the contamination persists. Depending on the importance and duration of the contamination, different dosages may be required. In any case, children must be given priority for prophylactic measures.
Subject(s)
Accidents , Iodides/therapeutic use , Iodine Radioisotopes/adverse effects , Nuclear Reactors , Adolescent , Adult , Child , Dose-Response Relationship, Drug , Humans , Iodides/adverse effects , Poland , Radionuclide Imaging , Thyroid Diseases/chemically induced , Thyroid Neoplasms/diagnostic imaging , Thyroid Neoplasms/drug therapy , UkraineABSTRACT
Les principes de la protection de public en cas dïaccident sont bien définis. Lïétablissement des niveaux de référence, relatifs a chaquemesure de protection, quel que soit le systeme de référence choisi, nécessite la meilleure connaissance possible des effets qui risquent dïapparaitre dans la population susceptible dïetre exposée. Les effects non stochastiques concernent des organes ou tissus bien déterminés: moelle osseuse, poumon, thyroide, peau ainsi que le foetus dans le cas dïexposition de femmes enceintes. Les formes de relations doseeffet concernant la plupart de ces organes sont en général suffisamment connues ainsi que les seuils auxquel les effets apparaissent. Cependant, lïincertitude sur les doses-seuils, les doses responsables de 50
et de 100
des effets, est, dans certains cas, du meme ordre de grandeur que lïintervalle DL0-DL100. Ces différences rendent dificile un pronostic quantifié des chances de survie dïune population éventuellement exposée dans la gamme de doses proposées pour la DL 50/60. En fait, les données nécessaires pour une prise de décision correcte nïont sans doute pas besoin dïetre affinées ni de recouvrir lïensemble des connaissances concernant la pathologie dïun organe ou dïun systeme. Il faut avant tout connaitre les niveaux de dose au-dessous desquels, dans une population normale, la probabilité dïapparition dïeffets non stochastiques est partiquement nulle. Cïest sur la base de ces doses-seuils que les autorités décideront du choix des niveaux de référence pour la mise en oeuvre de mesures de protection. (AU)
Subject(s)
Radioactive Hazard Release , Technology Assessment, Biomedical , Biomedical Technology , Pathology , Health Effects of DisastersABSTRACT
The total ionisation produced by ions stopped in nitrogen, methane and carbon dioxide has been measured in the energy range 25-375 keV using a chamber described previously. The chamber was operated alternately as a proportional counter and as an ionisation chamber to measure respectively the particle rate and the total ionisation produced. This procedure was repeated 20 to 40 times and a statistical treatment of the data was carried out. The average energy loss per ion pair (W-value), the associated standard deviation and the systematic error (+/- 2.5%) were determined for H+, He+, C+, N+, O+ and Ar+ ions stopping in the three gases. The W-value was found to be dependent on the velocity of the incident ions. For nitrogen gas, values range from 35 eV for 25 keV H+ to 84 eV for 25 keV O+. For methane, the values are 30.3 and 66.4 eV. For carbon dioxide, W-values range from 33.4 eV for 50 keV H+ to 135.9 eV for 25 keV Ar+. Finally, the Bragg additivity formula was tested for tissue-equivalent gas. The agreement between W-values calculated by this formula and those measured was found to be within 2% except for 25 keV O+ where the discrepancy is 10%.
Subject(s)
Energy Transfer , Gases , Ions , Argon , Carbon , Carbon Dioxide , Helium , Hydrogen , Mathematics , Methane , Nitrogen , Oxygen , Radiometry/instrumentationABSTRACT
The total ionization produced by ions stopped in argon and tissue-equivalent (TE) gas has been measured in the energy range 25-500 keV. A large ionization chamber was used for this study. The chamber was alternately operated as a proportional counter and as a ionization chamber to measure particle rate and the total ionization produced by them, respectively. The average energy loss per ion pair (W value) was found to be dependent on both the energy and mass of the incident ions. For argon gas the accelerated ions were H+, He+, Ar+; the W value ranges from 23.72eV for 25 keV H+ to 63.12 eV for 50 keV Ar+; Irregularities in the W value were found for He+ in the region 70-130 keV. For TE gas the accelerated ions were H+, He+, C+, N+, O+; the W value ranges from 29.13 eV for 25 keV H+ to 51.45 eV for 50 keV O+. Comparisions with existing data show a good agreement in the absolute values for TE gas and in the relative variations in argon gas. Differences between absolute values in argon might be due to impurities in composition.
