Source: TH
Subject: Science and Technology
Context: Nuclear scientists are divided over a study published in Current Science by BARC researchers questioning the viability of HALEU-Thorium (HALEU-Th) fuel for India’s reactors.
About HALEU-Thorium Fuel:
What It Is?
- HALEU-Th is an advanced nuclear fuel mix combining High Assay Low Enriched Uranium (HALEU) with Thorium. A specific commercial version of this fuel is called ‘ANEEL’ (Advanced Nuclear Energy for Enriched Life), developed by the U.S.-based company Clean Core Thorium Energy (CCTE).
How Fuel is Developed?
- Enrichment: Natural uranium is processed to increase the concentration of the fissile isotope U-235.
- Mixing: To create HALEU-Th, uranium is enriched to between 5% and 20% (HALEU) and then mixed with Thorium.
- Fission Process: While Thorium itself is not fissile (cannot sustain a chain reaction), the U-235 in the HALEU act as the driver to initiate and maintain the nuclear reaction, eventually converting Thorium into fissile U-233.
Types of Uranium in the Mix:
- Low Enriched Uranium (LEU): Contains less than 5% U-235 (used in most global reactors).
- HALEU: Contains 5% to 20% U-235 (used in ANEEL/HALEU-Th).
- Highly Enriched Uranium (HEU): Over 20% U-235 (restricted as it can be weapons-grade).
Key Features:
- High Burn-up: It offers a significantly higher energy output (up to 50–60 GWd/t) compared to natural uranium.
- Reduced Waste: The fuel produces significantly less spent fuel (radioactive waste)—only about 14% of what current reactors generate.
- Non-Proliferation: By keeping enrichment below 20%, the fuel remains unsuitable for nuclear weapons.
- Thorium Utilization: It allows for the immediate use of Thorium in existing Pressurised Heavy Water Reactors (PHWRs) without waiting for the third stage of India’s nuclear program.
Limitations:
- Reactor Design Changes: BARC scientists claim it is not a drop-in fuel; it may reduce the effectiveness of shutdown rods by 26%, requiring structural modifications to reactors.
- Cost & Availability: HALEU is commercially limited and expensive to produce or import.
- Reprocessing Issues: Unlike India’s traditional closed fuel cycle (which extracts plutonium from waste), HALEU-Th is not primarily designed for easy reprocessing.
