The industry newspaper "Country of Rosatom" published the impressions of Polina Brinza, a correspondent for the youth edition of "SR" and a bachelor's student at MEPHI specializing in nuclear energy and heat physics, about her internship at the MEPHI research reactor. Below, we present the full text of the publication.

Day One

We gather in the conference hall for a lecture on the goals and objectives of the internship. The company is diverse: there are mythologists, students from other Rosatom-affiliated universities, and even a physics teacher from St. Petersburg.

 After the lecture, we go to the laboratory of the Department of Theoretical and Experimental Physics of Nuclear Reactors. We examine a neutron generator that produces powerful neutron beams for research. We learn about gamma spectrometry. A spectrometer captures gamma quanta that emerge from a sample and identifies the isotopes present. This way, you can find out, for example, which radionuclides have accumulated in the reactor's nuclear fuel. We were shown how to collect a spectrum of a cobalt sample.

 Next on the program is a visit to the physics hall, where there are uranium-graphite and uranium-water stands, known as zero-power reactors. These stands contain natural uranium rods in graphite and water, respectively. When a neutron source is introduced, it generates a neutron flux that can be measured. The stands are subcritical, meaning that the reaction is not self-sustaining and will stop if the source is removed. The task for the interns is to calculate the conditions under which the stand will become critical. Spoiler: this won't work with natural uranium and water (water slows down neutrons well, but it also absorbs some of them, and in combination with a low concentration of uranium, there aren't enough "effective" neutrons to initiate a reaction), but it will work with natural uranium and graphite.

The starting point is to measure the neutron flux. You can measure it on a stand, or you can use a computer program: you select the parameters, and the result appears in a table.

But all further calculations must be carried out by yourself. This was the trainees' homework. Two nights were enough to calculate the relaxation coefficient, the material parameter, and the size of the critical assembly. There is another option for completing this work: in the virtual reality laboratory of MEPHI, which is an exact replica of the physical hall. Even the neutron fields inside the stands are visualized.

Days two and three

 Finally, we have reached the research reactor — ​IRT MIFI. The reactor building is a separate building. After passing several security lines (turnstile, checkpoint with a sentry and another turnstile), putting on robes and taking pocket dosimeters, we find ourselves at the goal. Now the reactor is stopped for the modernization of systems, but when it works, there is a full house. IRT produces huge streams of neutrons and gamma radiation. They can be used to study and modify materials, as well as to treat humans and animals. In the 1990s, the IRT was used for neutron capture therapy, successfully treating several dozen dogs for cancer.

 Let's climb up to the top of the reactor. There is a small window that allows us to view the interior of the core. When the reactor is operating, the water glows blue due to the Cherenkov radiation emitted by charged particles.

We were escorted to the control room. A lot of buttons, sensors and switches can be crazy at first glance, but in fact everything is optimized as much as possible — nothing superfluous. All the trainees were allowed to press the alarm button in turn. The button is very tight, this is done on purpose to prevent accidental pressing.

On weekdays, the IRT operates 24 hours a day, it is started on Monday morning and turned off on Friday evening for the weekend. There are three people in the control room: the shift supervisor, the control engineer (who starts and monitors the reactor together), and the on-duty dosimetrist. The room is filled with computers that record the readings of the sensors, which include the reactor parameters and the radiation environment. Once an hour, these parameters are manually entered into special logs. Both the paper logs and the computer records are kept until the end of the IRT's operation. This is done for two reasons: first, it provides valuable information for future generations, and second, it is a safety measure to ensure that the chronology of events can be reconstructed in the event of an accident.

The reactor has many control systems for neutron and gamma radiation, aerosols and gases. If at least one detector detects an excess, the emergency protection will be triggered and the reactor will shut down. The IRT is designed in such a way that if the water escapes somewhere, the reaction will die out on its own.

There are three circuits in the reactor cooling system, but only two are used. The fact is that during the design, scientists thought that the heating of steel during gamma irradiation would play a significant role, and the third circuit was needed for this purpose. However, it turned out that the contribution was not as significant, and additional cooling was not necessary.

Day four

We had to launch the IRT in virtual reality — ​quickly and efficiently. In the digital twin of the reactor, the console is duplicated, all the controls are as in reality, this is responsible for the mathematical model. To bring the reactor to power was not so easy, even with an accurate instruction. If the reactor accelerates too quickly or the power is too large, the emergency protection will be activated.

 We were divided into teams of three and started. The operator in the VR helmet started the reactor, and the operator's assistants followed the instructions, watching the monitor and providing moral support to the operator. The winning team completed the task in just over 16 minutes. My team finished second, with only a minute difference. Everything went according to plan, and there were no emergency shutdowns. The internship can be considered a success.