Students’ experiments at the Institute of Nuclear Techniques

1. Students’ experiments at theInstitute of Nuclear Techniques Budapest University of Technology and Economics (BME) www.reak.bme.hu Contact: Rita Dóczi doczi@reak.bme.hu

2. The basiclaboratory courses treat the experimental techniques and instrumentation most often used in nuclear physics experiments as well as in various other experimental sciences. They provide details on • interaction of radiation in matter; • radiation protection and radioactive sources; • statistics for the interpretation and analysis of data; • principles and operation of the main types of detectors (ionization, scintillation and semiconductor detectors); • nuclear electronics instrumentation; • various systems and techniques for elemental analysis.

5. Experiments related to the reactor physics courses: -Reactor operation exercise -Neutron activation analysis -Determination of thermal neutron flux in the reactor core using neutron activation analysis -Investigation of delayed neutron parameters, determining of uranium concentration in samples -Measurement of the void coefficient and the control rod reactivity worth -Measurement of thermal neutron diffusion length in graphite -Criticality experiment -Measurement of gamma- and neutron dose rate, radiation protection measurements

6. Reactor operation exercise This exercise is aimed at making the students familiar with the -construction, -operation, -nuclear and technological measuring systems, and -control system of nuclear reactors. A further goal is training the students the most important reactor manoeuvres.

7. Students • Learn how a nuclear reactor is controlled (measuring chains, control rods, etc.). • Study and perform manoeuvres, such as reactor startup, power increase and decrease, automatic and manual operation, shutdown. • Study the method of inserting or removing reactivity into or from the reactor core by moving the control and safety rods. • Learn how the safety systems intervene in case an error (either human or electronic) occurs. • Study the water circulation system, when and how these equipments should be operated. • Obtain information on the systems measuring technological parameters and their role in the safe operation of the reactor.

8. Neutron activation analysis Neutron Activation Analysis is a sensitive multi-element analytical technique used for both qualitative and quantitative analysis of major, minor, trace and rare elements.

9. Determination of thermal neutron flux in the reactor core using neutron activation analysis In this exercise, the relative distribution of the thermal neutron flux is determined along a vertical axis of the core. Then, the vertical reflector savings are determined. A wire of Dy-Al alloy containing 10% of Dy is used for the measurement of the neutron flux distribution. A gold activation detector determines the absolute value of thermal neutron flux.

11. Investigation of delayed neutron parameters, determining of uranium concentration in samples The aim of the measurement is the determination of the parameters of certain delayed neutron groups based on the time distribution of neutron emissions from a U sample after its irradiation in the reactor. In the second part of the measurement of the delayed neutrons are used to determine the U concentration of an unknown sample with the help of two standards.

12. Measurement of thermal neutron diffusion length in graphite • The experimental method used for determination of the diffusion length of the thermal neutrons is based on the investigation of the spatial distribution of the neutrons emitted by a steady state neutron source. • In this experiment the diffusion medium is graphite (what is often used both as a moderator and as a reflector). The measurements are made in the thermal column of the irradiation tunnel of the reactor.

13. Measurement of gamma- and neutron dose rate, radiation protection measurements The exercise is based on the proportionality between reactor performance and gamma and neutron dose rates. The shielding capacity of protecting materials (water and iron) against photon and neutron radiation occurring during the operation of anuclear reactor is determined.

14. Criticality experiment A knowledge of the source multiplication characteristics of a subcritical assembly is important for many reasons. It is required for safe approach to criticality by power and research reactors, and subcritical assemblies can be used to measure important reactor parameters. The experiment is started with measurements on the reactor operated as a subcritical system, then the reactor will be made first critical, then slightly subcritical and the excess reactivity will be determined.

15. Some other experiments Radiochemistry: basics of radioanalytical separation methods Environmental monitoring Measuring the activity of water samples from the river Danube

16. Students measure the 40K activity of their own body.