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The heavy water coolant is kept under pressure to avoid boiling, allowing it to reach higher temperature (mostly) without forming steam bubbles, exactly as for a pressurized water reactor (PWR). While heavy water is very expensive to isolate from ordinary water (often referred to as light water in contrast to heavy water), its low absorption of ...
Heavy Water Secondary coolant material Light Water Moderator material Heavy Water Reactor operating pressure, kg/cm 2 (g) 87 100 100 Active core height, cm 508.5 594 594 Equivalent core diameter, cm 451 – 638.4 Average fuel power density 9.24 KW/KgU 235 MW/m 3: Average core power density, MW/m 3: 10.13 12.1 Fuel Sintered Natural UO 2 pellets
The IPHWR (Indian Pressurized Heavy Water Reactor) is a class of Indian pressurized heavy-water reactors designed by the Bhabha Atomic Research Centre. [1] The baseline 220 MWe design was developed from the CANDU based RAPS-1 and RAPS-2 reactors built at Rawatbhata , Rajasthan.
Heavy water is less dissociated than light water at given temperature, and the true concentration of D + ions is less than H + ions would be for light water at the same temperature. The same is true of OD − vs. OH − ions. For heavy water Kw D 2 O (25.0 °C) = 1.35 × 10 −15, and [D + ] must equal [OD − ] for neutral water
This allows the reactor core to be built much more compactly, roughly half that of a CANDU of the same power. Additionally, it replaces the heavy water coolant in the high-pressure section of the calandria with conventional "light" water. This greatly reduces the amount of heavy water needed, and the cost of the primary coolant loop.
Currently water-cooled reactors account for over 95 per cent of all operating civilian power reactors globally while gas cooled ones make up about three per cent worldwide.
Overall, CANDU reactors use 30–40% less mined uranium than light-water reactors per unit of electricity produced. This is a major advantage of the heavy-water design; it not only requires less fuel, but as the fuel does not have to be enriched, it is much less expensive as well.
GE and Hitachi have developed the world’s safest Boiling Water Reactors (BWRs) over 60 years, with 40 reactors operating in 5 countries. BWRs and Pressurized Water Reactors (PWRs) both use light water as coolant and steam source, but BWRs generate steam directly in the reactor core, while PWRs use a secondary loop to produce steam. [24]