The design

The design
PALLAS has opted for a pool-type reactor. A specialisation frequently used is a tank-in-pool type reactor. The water basin provides space for fuel elements and control rods. The fuel elements are responsible for the formation of the neutrons during the nuclear fission. The PALLAS-reactor is designed to operate with low-enriched uranium, which means that the amount of uranium-235 (235U) is less than 20% of the total amount of uranium used (largely 238U).

The advantages of a ‘pool-type’ reactor are that the water basin provides sufficient shielding for safe experimentation and isotope irradiation in or near the reactor core during normal operation, and that experiments can be easily observed due to the water being transparent. The high density of the concrete walls of the basin also function as a guard for safe working.

Safety
Nuclear reactors must be operated safely. There are extensive international and national laws and regulations for this. This means that protecting people and the environment against the harmful effects of ionizing radiation during the entire lifetime of a nuclear reactor is sufficiently guaranteed. This is strictly monitored. The lifespan of a nuclear reactor includes the design, construction, commissioning, operations and, finally, its decommissioning and dismantling.

A nuclear reactor must, in essence, meet the three following safety functions:
1. Control reactivity;
2. Cool the nuclear materials;
3. Enclose the radioactive materials or nuclear fuels.

At PALLAS, a lot of attention is paid to safety: regarding the reactor core, but also regarding all other nuclear systems that are needed to operate the reactor safely. For example, the shell of the reactor will have to withstand possible dangers from outside, such as plane crashes or earthquakes. All lessons learned from the past (for example Fukushima and Chernobyl) are included in the design of the reactor.

PALLAS made an inventory of all functional requirements and compiled them in Technical Requirements. These requirements and all other steps are continuously tuned with the Authority for Nuclear Safety and Radiation Protection (ANVS). In addition, the latest international regulations of the International Atomic Energy Agency (IAEA) are always checked.

Image Quality Plan
The Image Quality Plan was delivered in 2017. This plan sets a framework and outlines how the reactor building will look. The opinions of local residents were taken into account.

Infrastructure
The design includes infrastructure, such as the cooling water supply, connections, sewerage, etc. Furthermore, it provides good logistics between all facilities, between the reactor and surrounding laboratories and office spaces.

The infrastructure during the construction is also discussed. For example, there must be room for construction buildings, construction traffic, parking spaces for construction workers and storage of materials. The effect of these temporary facilities on the daily course of events on the site and in the area must be kept to a minimum.