Final answer:
During a vertical containment technique, a nuclear reactor uses a three-part containment system (or shield) to protect against high temperatures, pressures, and radiation levels. The containment system is designed to prevent the release of significant radioactivity in case of an incident.
Step-by-step explanation:
During a vertical containment technique in the context of physics, a nuclear reactor employs a containment system or shield to protect against high temperatures, pressures, and radiation levels. This three-part structure consists of materials designed to safeguard the exterior of the reactor and operating personnel from the hazards within the reactor. For example, in the event of a loss-of-cooling incident, the containment vessel can prevent the release of significant radioactivity to the environment, as demonstrated in the Three Mile Island incident of 1979.