Fundamentals of Nuclear Power Notes

Fundamentals of Nuclear Power

Authored by Juan S. Giraldo, Douglas J. Gotham, David G. Nderitu, Paul V. Preckel, and Darla J. Mize of the State Utility Forecasting Group in December 2012.

Overview

Current State of Nuclear Power in the U.S.

  • The U.S. has 65 nuclear power plants operating 104 nuclear reactors.
  • The last reactor to come online was TVA's Watts Bar 1 in 1996.
  • Watts Bar 2 reactor is under construction and projected to come into service by 2013; construction was halted in 1988 due to decreased power demand.
  • Only two kinds of nuclear reactors are in commercial operation in the U.S.: Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR).
  • 69 of the operating reactors are PWRs, and 35 are BWRs.
  • Nuclear power plants represent 10% of the U.S. installed generating capacity but account for 20% of total U.S. electricity generation.
  • Nuclear power plants have high capacity factors (over 90%) due to intensive use and low fuel costs per unit of energy generated.
  • Capacity factor is defined as the amount of electricity generated over a period divided by the amount the plant would have generated at its maximum rated capacity.
  • Increased operating efficiencies and improved maintenance have resulted in increases in capacity factors from 56.3% in 1980, to 66% in 1990, to 91.1% in 2008.
  • Since 1990, output from nuclear plants has increased from 577 billion to 809 billion kWh, a 40% increase, despite little new capacity.
  • Output is expected to increase further due to power uprates, which increase the maximum heat output of the reactor core.
  • As of April 2011, the NRC had approved 139 uprates representing approximately 6,020 MW, equivalent to 6 nuclear power reactors.
  • Most operating reactors were constructed in the late 1970s and 1980s with 40-year operating licenses.
  • The NRC has been granting 20-year operating license extensions to increase the operational life of nuclear reactors to 60 years.
  • 71 reactor license extensions have been granted, 13 reactors have filed for extensions, and 19 more are expected to file.
  • Only two reactors are expected to end service before 2020: Kewaunee Power Station in Wisconsin (shut down in 2013) and Oyster Creek Generation station in New Jersey (expected to operate until the end of 2019).
  • The Kewaunee plant, a single 556 MW unit, is being decommissioned due to low wholesale electricity prices and lack of economies of scale.
  • San Onofre Nuclear Generating Station in California was shut down in January 2012 due to equipment problems.
  • Since 2007, there have been 17 applications to the NRC for new nuclear power plants.
  • Several have been suspended, but two have completed reviews and have construction underway (Vogtle in Georgia and Summer in South Carolina).
  • A Combined Operating License (COL) and Limited Work Authorization (LWA) were issued for the Vogtle site on February 10, 2012. A COL was issued for the Summer site on March 30, 2012.

Nuclear Power Around The World

  • There are 440 nuclear reactors in commercial operation in 31 countries, providing 14% of the world’s electricity.
  • The U.S. generates the largest amount of electricity from nuclear power, about one-third of the world’s generation, followed by France.
  • France relies on nuclear power for about 80% of its electricity needs.
  • There are currently 60 reactors under construction in 15 countries.
  • Construction is significant in China (27 reactors), Russia (10 reactors), South Korea (5 reactors), and India (6 reactors).
  • Before the 2011 Fukushima accident, Japan planned to increase nuclear power's share from 30% to over 40% before 2020.
  • Following the accident, Japan aimed to reduce dependency on nuclear energy as much as possible.
  • In September 2012, an advisory Cabinet panel endorsed a policy to completely phase out nuclear energy sometime in the 2030s, which the Japanese Cabinet hasn't fully committed to.
  • Following the Fukushima accident, all of Japan’s 50 reactors were shut down for safety checks, and only two were restarted in July 2012 to prevent power outages.
  • The Fukushima accident is expected to slow construction of new reactors, especially in Europe and Japan, and may only temporarily delay construction elsewhere.
  • Germany plans to shut down all 17 nuclear reactors by 2022 and the Swiss cabinet ruled that replacements for aging reactors would not be built, effectively ending the country’s nuclear program by 2034.
  • Belgium's Government is also considering ending their nuclear power program but has not agreed to a date to end operations.

Nuclear Energy

How Nuclear Power Plants Generate Electricity

  • Nuclear power plants generate electricity similarly to other thermal power plants.
  • They use the heat, is used to create steam, and the steam is used to spin turbines, which in turn generate electricity.
  • Instead of combustion, nuclear power plants use nuclear fission to generate heat.
  • Nuclear fission is the splitting of large atoms into smaller atoms, releasing vast amounts of energy.

Radioactive Decay

  • Nuclear fission can occur naturally (radioactive decay) or be induced.
  • Radioactive isotopes are elements with unstable nuclei that spontaneously decay into smaller atoms.
  • The average rate of decay is known as the