<h2>Overview</h2> <p>On <strong>6 April 2026</strong>, Prime Minister <strong>Narendra Modi</strong> announced on X that the <span class="key-term" data-definition="Prototype Fast Breeder Reactor – a 500 MW sodium‑cooled reactor built at Kalpakkam, marking the start of the second stage of India’s three‑stage nuclear programme (GS3: Energy).">PFBR</span> has attained <span class="key-term" data-definition="Criticality – the point at which a nuclear chain reaction becomes self‑sustaining; a prerequisite for power generation (GS3: Energy).">criticality</span>. This is the first time a fast breeder reactor in India has reached a self‑sustaining nuclear reaction, paving the way for larger scale use of indigenous thorium resources.</p> <h3>Key Developments</h3> <ul> <li>PFBR reached criticality after fuel loading on <strong>18 October 2025</strong>.</li> <li>Design capacity: <strong>500 MWe</strong> with a projected life of 40 years.</li> <li>Six additional 600 MW fast breeder units (FBR‑600) are planned, with twin units to be co‑located at Kalpakkam.</li> <li>The <span class="key-term" data-definition="Fast Reactor Fuel Cycle Facility – a re‑processing plant at Kalpakkam to recover plutonium from spent fast‑breeder fuel, essential for closing the fuel cycle (GS3: Energy).">FRFCF</span> is slated for completion by December 2027.</li> </ul> <h3>Important Facts</h3> <p>India’s nuclear fleet currently comprises 18‑20 <span class="key-term" data-definition="Pressurised Heavy Water Reactors – reactors that use natural uranium and heavy water as moderator, producing plutonium as a by‑product (GS3: Energy).">PHWRs</span>, totalling about <strong>7.48 GW(e)</strong>. These reactors generate the plutonium needed for the second stage, where fast neutrons in the PFBR convert fertile <span class="key-term" data-definition="Uranium‑238 – a non‑fissile isotope that, when bombarded by fast neutrons, breeds plutonium‑239 (GS3: Energy).">U‑238</span> into fissile <span class="key-term" data-definition="Plutonium‑239 – a fissile material produced in fast reactors, used as fuel or in weapons (GS3: Energy).">Pu‑239</span>. The ultimate goal is to breed <span class="key-term" data-definition="Uranium‑233 – fissile material obtained from thorium‑232, intended for the third stage of India’s nuclear programme (GS3: Energy).">U‑233</span> from abundant <span class="key-term" data-definition="Thorium‑232 – a fertile isotope abundant in India, which can be converted to U‑233 in the third stage (GS3: Energy).">thorium‑232</span>.</p> <p>The PFBR uses <span class="key-term" data-definition="Uranium‑Plutonium Mixed Oxide (MOX) fuel – a blend of uranium and plutonium oxides that enables fast reactors to achieve higher breeding ratios (GS3: Energy).">MOX</span> fuel and a blanket of U‑238. Its coolant is liquid <span class="key-term" data-definition="Sodium coolant – a low‑pressure, high‑thermal‑conductivity coolant used in fast reactors; its chemical reactivity poses safety challenges (GS3: Energy).">sodium</span>, which allows fast neutrons to persist but requires stringent leak‑prevention measures.</p> <h3>UPSC Relevance</h3> <p>The achievement illustrates India’s strategic push for energy security and nuclear self‑reliance, a frequent topic in GS III (Science & Technology). Understanding the three‑stage programme is essential for questions on energy policy, indigenous technology development, and the link between civilian nuclear power and strategic capabilities. The role of the <span class="key-term" data-definition="Atomic Energy Regulatory Board – the statutory body that grants safety clearances for nuclear installations in India (GS3: Energy).">AERB</span> in granting commercial operation permission highlights regulatory frameworks, relevant to GS III and GS II (Governance).</p> <h3>Way Forward</h3> <p>Before commercial operation, the PFBR must undergo low‑power tests and receive AERB approval. Parallel construction of the FRFCF will enable closed‑fuel‑cycle operations, reducing dependence on imported enriched uranium. Successful scaling of FBR‑600 units will accelerate the transition to the third stage, leveraging India’s vast thorium reserves to achieve long‑term energy security.</p>