The IPHWR-700 (Indian Pressurized Heavy Water Reactor-700) is an Indian pressurized heavy-water reactor designed by the NPCIL.[1] It is a Generation III reactor developed from earlier CANDU based 220 MW and 540 MW designs. It can generate 700 MW of electricity. Currently there is two unit operational, 6 units under construction and 8 more units planned, at a cost of ₹1.05 lakhcrore (US$13 billion).
Development
PHWR technology was introduced in India in the late 1960s with the construction of RAPS-1, a CANDU reactor in Rajasthan. All the main components for the first unit were supplied by Canada. India did the construction, installation and commissioning. In 1974, after India conducted Smiling Buddha, its first nuclear weapons test, Canada stopped their support of the project. This delayed the commissioning of RAPS-2 until 1981.[2]
After Canada withdrew from the project, research, design and development work in the Bhabha Atomic Research Centre and Nuclear Power Corporation of India (NPCIL) enabled India to proceed without assistance. India took help of Soviet Union whose VVER(Pressurised Water Reactor type) technology was used as a design for indigenization. Some industry partners did manufacturing and construction work. Over four decades, fifteen 220-MW reactors of indigenous design were built. Improvements were made in the original VVER design to reduce construction time and cost. New safety systems were incorporated. Reliability was enhanced, bringing better capacity factors and lower costs.
After a redesign to utilise excess thermal margins, the 540 MW PHWR design achieved a 700 MW capacity without many design changes. Almost 100% of the parts of these indigenously designed reactors are manufactured by Indian industry.[3]
Design
I-PHWR700 Model installed in GCNEP Office, Haryana
Zr-2.5% Nb pressure tubes separated from respective calandria tubes
A calandria tube filled with carbon dioxide (which is recirculated) to monitor pressure tube leak
It also has some new features as well, including:
Partial boiling at the coolant channel outlet
Interleaving of primary heat transport system feeders
A system to remove passive decay heat
Regional protection from over power
A containment spray system
A mobile fuel transfer machine
A steel lined containment wall
The reactor has less excess reactivity. Therefore, it does not need neutron poison inside the fuel or moderator. These designs handle the case of a loss of coolant accident such as occurred in the Fukushima Daiichi nuclear disaster.[5]
Operation
The reactor fuel uses natural uranium fuel with Zircaloy-4 cladding. The core produces 2166 MW of heat which is converted into 700 MW of electricity at a thermal efficiency of 32%. Because there is less excess reactivity inside the reactor, it needs to be refuelled continually during operation. The reactor is designed for an estimated life of 40 years.[6]
^Muktibodh, U.C (2011). "Design, Safety and Operability performances of 220 MWe, 540 MWe and 700 MWe PHWRs in India". Inter-Regional Workshop on Advanced Nuclear Reactor Technology for Near-term Deployment.