Hanford reactors
On which date did they start Reactor D?
Manhattan Project
Manhattan Project CIRUS reactor Thorium-based nuclear power Ford Nuclear Reactor Chernobyl disaster
Manhattan_Project-Hanford_reactors CIRUS_reactor-Abstract Thorium-based_nuclear_power-India Ford_Nuclear_Reactor-Review_Committee,_1997 Chernobyl_disaster-Steam_turbine_tests
Although an air-cooled design was chosen for the reactor at Oak Ridge to facilitate rapid construction, it was recognized that this would be impractical for the much larger production reactors. Initial designs by the Metallurgical Laboratory and DuPont used helium for cooling, before they determined that a water-cooled reactor would be simpler, cheaper and quicker to build. The design did not become available until 4 October 1943; in the meantime, Matthias concentrated on improving the Hanford site by erecting accommodations, improving the roads, building a railway switch line, and upgrading the electricity, water and telephone lines. As at Oak Ridge, the most difficulty was encountered while canning the uranium slugs, which commenced at Hanford in March 1944. They were pickled to remove dirt and impurities, dipped in molten bronze, tin, and aluminum-silicon alloy, canned using hydraulic presses, and then capped using arc welding under an argon atmosphere. Finally, they were subjected to a series of tests to detect holes or faulty welds. Disappointingly, most canned slugs initially failed the tests, resulting in an output of only a handful of canned slugs per day. But steady progress was made and by June 1944 production increased to the point where it appeared that enough canned slugs would be available to start Reactor B on schedule in August 1944. Work began on Reactor B, the first of six planned 250 MW reactors, on 10 October 1943. The reactor complexes were given letter designations A through F, with B, D and F sites chosen to be developed first, as this maximised the distance between the reactors. They would be the only ones constructed during the Manhattan Project. Some of steel, of concrete, 50,000 concrete blocks and 71,000 concrete bricks were used to construct the high building. Construction of the reactor itself commenced in February 1944. Watched by Compton, Matthias, DuPont's Crawford Greenewalt, Leona Woods and Fermi, who inserted the first slug, the reactor was powered up beginning on 13 September 1944. Over the next few days, 838 tubes were loaded and the reactor went critical. Shortly after midnight on 27 September, the operators began to withdraw the control rods to initiate production. At first all appeared well but around 03:00 the power level started to drop and by 06:30 the reactor had shut down completely. The cooling water was investigated to see if there was a leak or contamination. The next day the reactor started up again, only to shut down once more. Fermi contacted Chien-Shiung Wu, who identified the cause of the problem as neutron poisoning from xenon-135, which has a half-life of 9.2 hours. Fermi, Woods, Donald J. Hughes and John Archibald Wheeler then calculated the nuclear cross section of xenon-135, which turned out to be 30,000 times that of uranium. Fortunately, DuPont engineer George Graves had deviated from the Metallurgical Laboratory's original design in which the reactor had 1,500 tubes arranged in a circle, and had added an additional 504 tubes to fill in the corners. The scientists had originally considered this overengineering a waste of time and money, but Fermi realized that by loading all 2,004 tubes, the reactor could reach the required power level and efficiently produce plutonium. Reactor D was started on 17 December 1944 and Reactor F on 25 February 1945.
CIRUS (Canadian-Indian Reactor, U.S.) was a research reactor at the Bhabha Atomic Research Center (BARC) in Trombay near Mumbai, India. CIRUS was supplied by Canada in 1954, but used heavy water (deuterium oxide) supplied by the United States. It was the second nuclear reactor to be built in India. It was modeled on the Canadian Chalk River National Research X-perimental (NRX) reactor. The 40 MW reactor used natural uranium fuel, while using heavy water as a moderator. It is a tank reactor type with a core size of 3.14 m (H) × 2.67 m (D). It first went critical July 10, 1960. The reactor was not under IAEA safeguards (which did not exist when the reactor was sold), although Canada stipulated, and the U.S. supply contract for the heavy water explicitly specified, that it only be used for peaceful purposes. Nonetheless, CIRUS produced some of India's initial weapon plutonium stockpile, as well as the plutonium for India's 1974 Pokhran-I (Codename Smiling Buddha) nuclear test, the country's first nuclear test. At a capacity factor of 50–80%, CIRUS can produce 6.6–10.5 kg of plutonium a year.CIRUS was shut down in September 1997 for refurbishment and was scheduled to resume operation in 2003. The reactor was brought back into operation two years late in 2005. During refurbishing, a low-temperature vacuum evaporation-based desalination unit was also coupled to the reactor to serve as demonstration of using waste heat from a research reactor for sea desalination. Even if the reactor has a life of twenty more years, India had declared that this reactor would be shut down by 2010 in accordance with the Indo-US nuclear accord reached between Indian Prime Minister Manmohan Singh and US President George W. Bush. The reactor was shut down on 31 December 2010. 
In February 2014, Bhabha Atomic Research Centre (BARC), in Mumbai, India, presented their latest design for a "next-generation nuclear reactor" that will burn thorium as its fuel ore. Once built, with a target date of 2016, they estimate that the reactor could function without an operator for 120 days. According to Dr R K Sinha, chairman of their Atomic Energy Commission, "This will reduce our dependence on fossil fuels, mostly imported, and will be a major contribution to global efforts to combat climate change." Because of its inherent safety, they expect that similar designs could be set up "within" populated cities, like - Mumbai or Delhi. India's government is also developing up to 62, mostly thorium reactors, which it expects to be operational by 2025. It is the "only country in the world with a detailed, funded, government-approved plan" to focus on thorium-based nuclear power. The country currently gets under 3% of its electricity from nuclear power, relying for the rest on coal and oil imports. It expects to produce around 25% of its electricity from nuclear power. In 2009 the chairman of the Indian Atomic Energy Commission said that India has a "long-term objective goal of becoming energy-independent based on its vast thorium resources. "In late June 2012, India announced that their "first commercial fast reactor" was near completion making India the most advanced country in thorium research." We have huge reserves of thorium. The challenge is to develop technology for converting this to fissile material," stated their former Chairman of India's Atomic Energy Commission. That vision of using thorium in place of uranium was set out in the 1950s by physicist Homi Bhabha. India’s first commercial fast breeder reactor — the 500 MWe Prototype Fast Breeder Reactor (PFBR) — is approaching completion at the Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu. As of July 2013 the major equipment of the PFBR had been erected and the loading of "dummy" fuels in peripheral locations was in progress. The reactor was expected to go critical by September 2014. The Centre had sanctioned Rs. 5,677 crore for building the PFBR and “we will definitely build the reactor within that amount,” Mr. Kumar asserted. The original cost of the project was Rs. 3,492 crore, revised to Rs. 5,677 crore. Electricity generated from the PFBR would be sold to the State Electricity Boards at Rs. 4.44 a unit. BHAVINI builds breeder reactors in India. India's 300 MWe AHWR (pressurized heavy water reactor) reactor began construction in 2011. The design envisages a start up with reactor grade plutonium that will breed U-233 from Th-232. Thereafter thorium is to be the only fuel. 
In June 1997, the Ford Nuclear Reactor Review Committee submitted a report to the Vice President for Research (Vince Pecoraro, at the time) on the future of the FNR. The Committee estimated thatthe reactor was costing the university $1 million / year. Letters had been sent to various university departments as well as to other institutions that made use of the reactor, asking for input on their use of the facility. Alex Halliday and Eric Essene from the department of Geology relied heavily on the reactor for their research in Ar-40—Ar-39 aging, and sent strong praise of the reactor. Gary Was from the department of Nuclear Engineering and Radiological Sciences explained that over 15 NERS courses rely on the reactor, as well as nearly every professor's research. The Museum of Anthropology also suggested that the loss of the reactor would have serious adverse impacts on the students and faculty. Several other departments, such as the Chemistry department, said that they had not used the reactor in 30 years and did not plan to in the future. Outside the University community, the Michigan State University Department of Geological Science, Louisiana State University, the University of Nevada Las Vegas, Buchtel College of Arts and Sciences, the University of California Santa Barbara, the University of Georgia, Oak Ridge National Laboratory, NIST, the NRC, Sandia National Labs, EPRI, Ford, and GM all expressed interest in keeping the reactor operational, while NASA (among others) had no interest. The final decision was to shut down and decommission the reactor. The statement given by UM Vice President for Research was:In recent years, however, the reactor's use by the U-M academic community has declined substantially to the point where the bulk of the users now come from the federal government and industry. Given this change, the University can no longer justify the reactor's substantial cost of operation, which now largely subsidizes non-University users. 
An inactive nuclear reactor continues to generate a significant amount of residual decay heat. In an initial shut-down state (for example, following an emergency SCRAM) the reactor produces around 7 percent of its total thermal output and requires cooling to avoid core damage. RBMK reactors, like those at Chernobyl, use water as a coolant. Reactor 4 at Chernobyl consisted of about 1,600 individual fuel channels; each required a coolant flow of 28 metric tons () per hour. Since cooling pumps require electricity to cool a reactor after a SCRAM, in the event of a power grid failure, Chernobyl's reactors had three backup diesel generators; these could start up in 15 seconds, but took 60–75 seconds to attain full speed and reach the 5.5megawatt (MW) output required to run one main pump. To solve this one-minute gap, considered an unacceptable safety risk, it had been theorised that rotational energy from the steam turbine (as it wound down under residual steam pressure) could be used to generate the required electrical power. Analysis indicated that this residual momentum and steam pressure might be sufficient to run the coolant pumps for 45 seconds, bridging the gap between an external power failure and the full availability of the emergency generators. This capability still needed to be confirmed experimentally, and previous tests had ended unsuccessfully. An initial test carried out in 1982 showed that the excitation voltage of the turbine-generator was insufficient; it did not maintain the desired magnetic field after the turbine trip. The system was modified, and the test was repeated in 1984 but again proved unsuccessful. In 1985, the tests were attempted a third time but also yielded negative results. The test procedure was to be repeated again in 1986, and it was scheduled to take place during the maintenance shutdown of Reactor Four. The test focused on the switching sequences of the electrical supplies for the reactor. The test procedure was to begin with an automatic emergency shutdown. No detrimental effect on the safety of the reactor was anticipated, so the test program was not formally coordinated with either the chief designer of the reactor (NIKIET) or the scientific manager. Instead, it was approved only by the director of the plant (and even this approval was not consistent with established procedures). According to the test parameters, the thermal output of the reactor should have been "no lower" than 700 MW at the start of the experiment. If test conditions had been as planned, the procedure would almost certainly have been carried out safely; the eventual disaster resulted from attempts to boost the reactor output once the experiment had been started, which was inconsistent with approved procedure. The Chernobyl power plant had been in operation for two years without the capability to ride through the first 60–75 seconds of a total loss of electric power, and thus lacked an important safety feature. The station managers presumably wished to correct this at the first opportunity, which may explain why they continued the test even when serious problems arose, and why the requisite approval for the test had not been sought from the Soviet nuclear oversight regulator (even though there was a representative at the complex of 4 reactors). The experimental procedure was intended to run as follows:  The reactor was to be running at a low power level, between 700 MW and 800 MW. The steam-turbine generator was to be run up to full speed. When these conditions were achieved, the steam supply for the turbine generator was to be closed off. Turbine generator performance was to be recorded to determine whether it could provide the bridging power for coolant pumps until the emergency diesel generators were sequenced to start and provide power to the cooling pumps automatically. After the emergency generators reached normal operating speed and voltage, the turbine generator would be allowed to freewheel down.  