small nuclear power reactors

Small nuclear power reactors

There is revival of interest in small and simpler units for generating electricity from nuclear power, and process heat. This interest in small and medium nuclear reactors is driven by a desire to reduce capital cost and provide power away from large grid systems. The technologies involved are very diverse. As nuclear power generation has become established since 1960, the size of reactor units has grown from 60 Mwe  to more than 1600 Mwe ,with corresponding economies of scale in operation. At the same time there have been many hundreds of smaller reactors built both for naval use (up to 100 MW thermal )and neutron sources, yielding enormous expertise in the engineering small units .

The international Atomic Energy Agency (IAEA) defines small as under 300 MWe and up to 700MWe as medium-including managing operational units from 20th century . Together they are now referred to as small and medium reactors (SMRs). This power focus an advanced designs in small category, those now being built for the first time or still on drawing board.

Today due to party high capital cost of larger power reactors generating electricity via steam cycle and party to need to service small electricity grids about 4 Gwe there is move to develop smaller units. These may be built independently or as modules in large complex with capacity added incrementally as required. Economics of scale are provided by number produced. There also moves to develop small units for remote sites. Generally modern small reactors for power generation are expected to have greater simplicity of designs, economy of mass production, and reduce site costs. Most are also designed for a high level passive or inherent safety in the event of malfunction.

A 2010 report by special committee convened by American nuclear society showed that many safety provisions necessary or at least prudent in large reactors are not necessary in small designs forth coming.

A 2009 assessment by IAEA under its innovative nuclear power reactors & fuel cycles (NPRO)program concluded that there could be 96 smaller modular reactors (SMRs) in operation around the world by 2030 in its high case, and 43 units in low case none of them in U.S.

The most advanced modular projects in China, where Chinery is preparing to build the 210 Mwe HTR-PM which consists of twin 250 Mwt reactors. In South Africa Pebble Bed Modular Reactor (pty) Limited  and Eskom had been developing the Pebble bed modular reactor (PBMR) of 200 Mwt  (80MWe ) but funding to this project has been stopped. A U.S. led by General Atomic is developing another design-the gas turbine modular helium reactor (GT-MHR )-with 600 G wt(285MWe ) modules driving a gas turbine directly, using helium as coolant and operating at very high temperatures. All three models are high temperature gas cooled reactors (HTRs) while build an experience of several innovative reactors in the 1960 and 1970.

Another significant line of development  is in very small fast reactors of under 50MWe . Some are conceived for areas away from transmission grids and with small loads, others are designed to operate in clusters in competition with larger units. Already  a operating in a remote corner of Siberia are four small units at the Bilibino co-generation plant. These four 62 Mwt (thermal ) units are an unusual graphite modulated boiling water design with water/steam channel though the moderator . They produce steam for district heating and 11MWe (net) electricity each . They have performed well since 1976, much more cheaply than fossil fuel alternatives in Arctic region.

Also in the small reactor category  are the Indian 220 Mwe  pressurized heavy water reactors (PHWRs) based Canadian technology and Chinese 300-325 Mwe , PWR such as built at Qinshan phase -1 at Chashma in Pakistan , and now called CNP-300 . These design are detailed in this paper simply because they are well established. The Nuclear Power Corporation of India (NPCIL ) is now focusing on 540 MWe and 700 MWe version of its PHWR and is offering both 220 and 540MWe  version internationally. These small established design are relevant to situations required small to medium units though they are not state of art technology.

U.S. president Obama   approved 54.5 billion dollars stimulus for industry saying that nuclear power “ A necessary step “  in eliminating our dependence on fossil fuels. But there are more than green backs fully this nuclear renaissance . Small modular reactors (SMRs)  are dissipating nuclear fears  and renewing interest in the 30 year stagnant industry.

That because SMRs may success-ed when older nuclear design fall short. From utility perspective  SMRs are less capital insensitive and easier to install. Instead of adding 1+GW all at once to grid base generation, SMRs add manageable 30MW to 300 MW. But utilities don’t have to stop at one SMR,they can chain this together on the same plant. The Babcock and Wilcox company’s  m power of reactor for example can chain 10 or more SMRs together on the same site, giving them the power of bigger reactor with advantages of smaller ones.

Utilities and their regulators however are not only people developing a taste for SMRs. Many Americans are becoming aware of their increased safety measures. The m power light water reactors (LWR) for instance has ability to perform passively safe power  down -which means no more Chernobyl’s. Melt  down theoretically occur when loss of coolants triggers an uncontrollable reaction. This reactor however is designed  to slow down the fission rate without  a coolant or even  action by human agent.

In addition to safety the newer reactors are also tacking problem of waste . The Unites States has up word  of 77,000 tons of it. This waste however has 90 per cent of its potential nuclear energy  still locked inside. Hoping to take advantage of these remains, General Atomic is designing the energy multiplier module breeder reactor that uses some that left over energy. Nuclear waste  may be a reality for now, but at least newer reactors are getting more out of it.