Indigenously built PFBR at Kalpakkam hits criticality

[Imtiaz]

Source: https://x.com/i/status/2041187159655305350

[Nikita]

Here's a quick rundown of India's three‑stage nuclear programme:

Stage 1 – Pressurised Heavy Water Reactors (PHWR)
Fuel: Natural uranium.
What they do: Use uranium to generate electricity and, as a side‑product, turn the non‑fissile part into plutonium‑239.
Status: Fully mature and supplies most of our nuclear power today.

Stage 2 – Fast Breeder Reactors (FBR)
Fuel: A blend of plutonium‑239 (from Stage 1) and uranium.
The breeder bit: While generating power they convert a blanket of uranium‑238 into more plutonium.
Thorium introduction: Later in this stage we add a thorium blanket to breed uranium‑233.
Status: The PFBR at Kalpakkam, which has just gone critical, is the flagship.

Stage 3 – Thorium‑based reactors
Fuel: Uranium‑233 (produced in Stage 2) plus thorium.
Goal: Harness India's huge thorium reserves to run reactors for centuries.
How it works: Thorium itself isn't fuel; it's fertile. In the reactor it becomes uranium‑233, which then sustains the chain reaction.
Status: Still in R&D, experimental phase expected to wrap up by 2023.

[Chandan]

Congratulations to everyone involved