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Safety

This section explains, from a balanced standpoint, why fusion reactors are said to be safe and what challenges still remain. Fusion has several safety advantages that fission does not, but it does not mean that no radioactive material is involved at all. Let us build up an understanding of both the strengths and the challenges, starting gently from the high school level.

What You Will Learn in This Section

Section titled “What You Will Learn in This Section”

The safety of fusion can be understood from three broad perspectives.

The first is the inherent safety features that fusion possesses. Because there is no chain reaction like the one in a fission reactor, it cannot run away; the amount of fuel inside the reactor (the fuel inventory) is extremely small; and the decay heat generated after the reactor is shut down is low. These are the reasons fusion is said to be intrinsically resistant to accidents.

The second is the handling of tritium, the fuel. Tritium is a radioactive form of hydrogen and requires care in handling. How to confine it and how to manage the total amount within a facility are at the heart of safety design.

The third is the waste produced by activation. When the high-energy neutrons released in the fusion reaction strike the structural materials of the reactor, the materials themselves become radioactive. No long-lived high-level waste like that from fission is produced, but the handling of activated materials remains a challenge.

Reading Order

Section titled “Reading Order”

First, use this index page to grasp the overall picture of fusion safety, both its advantages and its challenges. After that, we recommend reading in the following order.

  1. Tritium Management: Learn the properties of tritium, the fuel, why its radiation is relatively easy to handle, and how it is confined and accounted for within a facility.
  2. Radioactive Waste: Learn how activation by neutrons works, how the waste differs from that of a fission reactor, and the idea of low-activation materials.

Tritium is a fuel-related issue you face constantly during operation, while activated waste is a materials issue that persists until the reactor is dismantled. Reading along the timeline from operation to decommissioning helps the whole picture come together.

Prerequisite Knowledge

Section titled “Prerequisite Knowledge”

This section is easier to understand if you know how the fusion reaction itself works. If you have not yet, checking the Basics first for the D-T reaction (the reaction between deuterium and tritium) and where the neutrons come from will make the safety discussion much easier to follow.

For a Balanced View

Section titled “For a Balanced View”

When discussing the safety of fusion, it is not fair to emphasize only the advantages, nor only the challenges. The absence of a chain reaction so that it cannot run away, the small amount of fuel, and the low decay heat are genuine strengths of fusion. On the other hand, the challenges of handling tritium, a radioactive fuel, and of materials being activated by neutrons are real. In this section, we value presenting both side by side.

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