In News:

Researchers from the Double Chooz Collaboration in France have reported the first high-precision measurement of the energy signature of antineutrinos emitted by spent nuclear fuel. The finding could provide a new method for the remote monitoring and verification of nuclear facilities.

What are Neutrinos and Antineutrinos?

• Neutrinos are extremely light, electrically neutral subatomic particles that interact very weakly with matter. As a result, enormous numbers of them can pass through matter, including the human body, with very little interaction.
• During nuclear fission, large quantities of antineutrinos are produced. Importantly, antineutrino emissions do not stop immediately when a nuclear reactor is shut down.

Antineutrinos from Spent Nuclear Fuel

• Radioactive isotopes present in partially used and spent nuclear fuel continue to undergo radioactive decay and emit antineutrinos. Isotopes such as praseodymium-144 and rhodium-106 contribute to this residual antineutrino flux.
• The Double Chooz study detected this residual signal and found that approximately 56% originated from fuel in reactor cores, while 44% came from spent fuel stored in nearby cooling pools.

Significance for Nuclear Safeguards

The predictable antineutrino signal could potentially act as a remote fingerprint of nuclear fuel inventories. Any significant change in the detected flux could indicate the movement or removal of fuel assemblies, allowing inspectors to monitor facilities without directly accessing them.

In the future, neutrino detectors could potentially help estimate plutonium content in reactor cores and detect premature fuel removal that could be associated with attempts to produce weapons-grade plutonium. Thus, the technology has potential applications in nuclear safeguards and non-proliferation.