Tečaj za študente Univerze v Uppsali

Od 28. septembra do 1. oktobra smo gostili študente Univerze v Uppsali. To je v zadnjih letih postal že tradicionalen tečaj, ki poteka v zadnjem tednu septembra. Letos so se nam študentje lahko ponovno pridružili osebno, saj trenutna COVID-19 situacija to omogoča. V štirih dneh so se študentje spoznali z našim reaktorjem in opravili šest praktičnih vaj. Njihovim profesorjem je bila najbolj zanimiva vaja Meritev koeficienta praznin, kjer vpihujemo zrak v sredico reaktorja med obratovanjem na nizki moči. Tako simuliramo vrenje vode v reaktorju, študentje pa opazujejo kako praznine vplivajo na moč reaktorja. Študentom je bil najbolj zanimiv zadnji dan, ko so lahko tudi sami upravljali reaktor.

Kalorimetrične meritve v reaktorju TRIGA

Ta teden gostimo raziskovalca Damiena in Huberta iz CEA Cadarache. Skupaj izvajamo meritve s kalorimetri. Opazujemo koliko se posamezni materiali segrevajo zaradi sevanja v centralnem obsevalnem kanalu pri različnih močeh reaktorja Takšnih meritev do sedaj še nismo izvajali in rezultati nam bodo koristili pri našem prihodnjem raziskovalnem delu.

Univerza Aix Marseille na virtualnem tečaju

7. in 9. julija smo gostili študente z Univerze Aix Marseille. Zaradi že dobro poznanih omejitev, ki otežujejo potovanja med državami, smo jih gostili le v virtualnem smislu. V sredo smo jim pripravili ogled reaktorja TRIGA, v petek pa smo izvedli vajo Porazdelitev nevtronskega fluksa znotraj sredice reaktorja TRIGA.

Virtualni ogled raziskovalnega reaktorja TRIGA

Že več mesecev je onemogočeno normalno življenje zaradi preprečevanja širjenja virusa COVID-19. Na reaktorju TRIGA smo bili primorani odpovedati vse skupinske oglede našega laboratorija kamor spadajo tudi vsi obiski šolarjev. Vsako leto nas obišče skoraj 1500 slovenskih učencev. Da letošnja generacija ne bo prikrajšana za obisk raziskovalnega reaktorja, smo zaposleni posneli zanimiv video. Gledalce popeljemo skozi komandno sobo na ploščad reaktorja, od koder si ogledamo reaktor med obratovanjem na polni moči. Sledi še sprehod skozi Objekt vroče celice, kjer operaterji lahko varno rokujemo z radioaktivnimi materiali. Video si lahko ogledate na našem YouTube kanalu »JSI TRIGA research reactor«.

Exercise No. 15: Primary water activation

Purpose of experiment

The water activation experiment serves as a demonstration of the creation of radioactive isotopes from nuclear reactions with fast neutrons in pure water. The main reaction product, N-16, is important from the radiation protection standpoint, as it emits energetic and highly penetrating gamma rays, in water-cooled fission and fusion devices. Conversely, measurements of the activities of the product radioactive isotopes represent an independent method of monitoring of the reactor power, leak detection, etc.

Outcome / What you will learn
Students will:

  1. Observe methods for measuring of the activation of the primary water;;
  2. Measure the activity of primary water as a function of the reactor power.
Execution
  1. Set up of the experiment on the reactor platform (water activation loop, lead shielding, detectors);
  2. Discussion on the detectors;
  3. Detector energy calibration using radioactive calibration sources;
  4. Measurements of the activity of individual nuclides and the total dose rate as a function of reactor power;
  5. Discussion of the results.

Exercise No. 14: Indoor radon measurements

Purpose of experiment

The purpose of the exercise is to measure the activity of radon and radon progeny in an indoor environment. Radon is one of the products of the 238U decay chain and it is the only one in gaseous form, and therefore the only one that can escape the out of the Earth’s crust. Radon may represent a significant contribution to natural radiation exposure, especially in karstic terrain (for which Slovenia is renowned), and after smoking, is the second most important cause of lung cancer.

Outcome / What you will learn
Students will:

  1. discuss the formation of radon through radioactive decay and diffusion into the atmosphere;
  2. perform simple experiments to demonstrate the presence of radon by detection of alpha radiation;
  3. perform radon concentration measurements using the Kuznetz method, by filtering radon progeny from the air and subsequent gamma spectrometry measurement.
Execution
After a discussion on the formation of radon through radioactive decay and its diffusion into the atmosphere, students:

  1. capture radon progeny onto electrostatically charged balloons and measure the emitted alpha particles;
  2. perform radon concentration measurements using the Kuznetz method by:
    • filtering radon progeny from the air onto filter paper using a vacuum cleaner
    • gamma spectrometry measurements of the filter paper
    • analysis of the recorded gamma spectrum
    • determination of the radon concentration from the measured radon progeny activities

Exercise No. 13: Neutron activation analysis

Purpose of experiment

The purpose of the experiment is a demonstration of the relative neutron activation analysis technique (NAA). This technique is widely used in a variety of fields (e.g. environmental sciences, forensic science, analysis of geological and inorganic materials, foodstuff, etc.). It plays a key role within environmental specimen banking programmes.

Outcome / What you will learn
Students will:

  1. prepare samples and standards for irradiation in the neutron field of a nuclear reactor
  2. perform the irradiations and measure the gamma spectra of the irradiated samples and standards
  3. analyse gamma spectra and determine analyte concentrations
Execution
  1. Preparation and weighing of samples and standards;
  2. Encapsulation of the test portions and standards in e.g. polyethylene foil / capsules;
  3. Neutron irradiation of samples and standards;
  4. Sequential measurements of the induced radio activities in samples and standards by gamma-ray spectrometry;
  5. Interpretation of the gamma-ray spectra (i.e. peak fitting;
  6. Calculation of the concentrations in the samples.

Exercise No. 12: Gamma spectrometry

Purpose of experiment

Gamma (ray) spectrometry is a widely used measurement technique in which gamma ray spectra originating from radioactive isotopes are analyzed. The purpose of the experiment is to demonstrate the gamma spectrometry technique by performing gamma spectrum measurements for a selection of radioactive sources. The complex features in the recorded gamma spectra are visualized and their origins explained; radionuclide activities are determined on the basis of the measured spectra, the basic nuclear data and the calibrated detection efficiency.

Outcome / What you will learn
Students will:

  1. gain experience in gamma spectrometry measurements
  2. visualize and understand the complex features in recorded gamma spectra
  3. analyse gamma spectra
  4. determine the activity of radionuclides in measured radioactive sources.
Execution
  1. A multi-isotope standard is measured. Various gamma lines are detected and described.
  2. Previously irradiated samples of certified reference materials (e.g. Al-Au, Al-Co, Al-Th) are measured using gamma ray spectroscopy. Students identify the main characteristics (Backscatter and Compton edge, full energy peak, sum peak from pile-up, single and double escape peaks) in the gamma ray spectra.
  3. The activities of the radionuclides in the samples are determined on the basis of the calibrated detection efficiency.
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