A history of NRU reactor operation

1950:
Mar 31 ZEEP went critical for first time since it was shut down in 1947, to supply heavy water for NRX. ZEEP was used in the NRU design process. {Eggleston}
1957:
Nov 3 The 135 MW National Research Universal (NRU) at Chalk River Nuclear Laboratories attains first criticality at 06:10.
1958:
May 23 NRU reached full power of 200 MW (th) for first time.
May 24 NRU had a fuel rod failure, which broke upon removal and fell to the floor. The fuel rod caught fire and spread contamination.
Aug 15 NRU restarted after May 24 fuel rod fire.
1964:
Mar Completion of conversion of AECL's National Research Universal (NRU) reactor from natural uranium to high-enriched fuel. {Canada Enters the Nuclear Age}
1970:
May 1 NRU production of molybdenum-99 began.
1972:
Jun 5 NRU shut down for refurbishment. {JW}
1974:
Aug 2 NRU returned to service after major refurbishment, including reactor vessel change. {JW}
1991:
NRU began conversion from high-enriched (HEU) to low-enriched (LEU) fuel. Completed in 1992.
2000:
Jan 14 Arrival of test bundles of American mixed oxide (MOX) fuel at AECL's Chalk River Laboratories. This fuel, containing about 3% weapons-grade plutonium surplus to American nuclear weapons (the remainder of the fuel is the usual uranium oxide), is to be tested in the NRU research reactor to see if MOX from weapons-grade Pu can be used in a CANDU reactor. The tests are part of a Canadian government proposal to reduce worldwide weapons plutonium by "burning" it in reactors. The utilisation of MOX in power reactors would use up much of the plutonium, denature the remainder (contaminate it with non-weapons plutonium isotopes), and contaminate it with fission products (the radioactive waste in used reactor fuel). All while generating electricity.
Feb 19 MMIR-1, the first of two new MAPLE medical isotope production reactors at Chalk River Laboratories, attained first criticality at 2:53 a.m. This is the world's first reactor of the new millenium. The two MAPLE reactors at CRL, and the associated processing plant, are for medical isotope processing for MDS Nordion. The new reactors will replace the medical isotope production presently done in the NRU reactor. Sep 25 Arrival of Russian test bundles of mixed oxide (MOX) fuel at the Chalk River Laboratories of AECL (see Jan 14 2000). This fuel, about 3% plutonium surplus to Russian nuclear weapons plus uranium oxide, is to be tested in the NRU research reactor.
2001:
Feb 3 Beginning of the test of mixed oxide (MOX) fuel bundles at AECL's Chalk River Laboratories, as the NRU reactor went critical at 8:00 am. This fuel, containing about 3% weapons-grade plutonium surplus to Russian and American nuclear weapons (the remainder of the fuel is the usual uranium oxide), is being tested in the NRU research reactor to see if MOX from weapons-grade Pu can be used in a CANDU reactor.
2007:
Jan 18 AECL's National Research Universal (NRU) research reactor attained 1 million MW days since the last calandria vessel change. NRU re-entered service on August 2 1974, following a two-year shutdown for refurbishment. {AECL} June 15 The National Research Council unveiled Canada’s first neutron reflectometer for the Canadian Neutron Beam Centre. Neutrons are supplied by AECL's National Research Universal
(NRU) reactor at Chalk River Laboratories. {NRC/CNRC}
Nov 18 NRU taken out of service for maintenance and to address licensing issues arising over emergency power supply connections to two coolant pumps. The EPS is a seismically-qualified backup system in addition to other backup power supplies. {AECL}
Dec 11 Canadian Parliament passed legislation C-38, with all parties in support, allowing AECL to restart NRU for a 120-day period for medical radioisotope production, while the emergency power system was connected to primary pumps P-104 and P-105. For more detail on the NRU licensing issue, see the Canadian Nuclear FAQ description.
Dec 16 NRU returned to service, 03:44, following commissioning of primary pump P-105 starter motor, connected to seismically-qualified emergency power system. {AECL}
2008:
Feb 2 NRU restarted at 00:40, following commissioning of primary pump P-104 starter motor, conected to seismically-qualified emergency power system. This was 53 days after Dec 11 federal legislation C-38 was passed, which had given 120 days to complete the work. {AECL}
2009:
Jan 16 NRU U1 experimental loop recommissioned and ACR fuel testing commenced. The U1 loop is used to subject fuels and materials to high neutron fluxes under power reactor conditions.{AECL}
May 14 Loss of grid in eastern Ontario trips NRU reactor at Chalk River. During restart, a leak of ~5 kg/hr of heavy water was discovered. Restart was halted {AECL}
May 18 NRU leak location determined, from bottom of calandria vessel into J-rod annulus. Extended outage (>1 month) for calandria vessel repair announced. This is an interruption of a major supplier of medical radioisotopes (esp. Mo-99 for Tc-99m imaging diagnostics). {AECL}
May 22 Last molybdenum-99 targets removed from NRU. {AECL}
June 2 First fuel removed from NRU {AECL}
June 15 Last fuel removed from NRU {AECL}
2010:
Aug 17 NRU was safely returned to operation.
2011:
May 15 NRU was shutdown for a 33-day planned shutdown.
June 16 NRU was successfully returned to service after the successful 33-day planned shutdown. This extended outage enabled AECL to carry out more extensive maintenance and inspection in order to fulfill its commitment to the Canadian Nuclear Safety Commission.
2012:
April 15 NRU was shutdown for a 1-month planned shutdown. The purpose of the outage is to conduct scheduled inspection and maintenance including annual vessel inspection.
May 16 NRU was successfully returned to service.. 

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