Neutron News ISSN: 1044-8632 (Print) 1931-7352 (Online) Journal homepage: http://www.tandfonline.com/loi/gnnw20 Canada's Neutron Source, the NRU reactor, closes Daniel Banks To cite this article: Daniel Banks (2018) Canada's Neutron Source, the NRU reactor, closes, Neutron News, 29:2, 25-31, DOI: 10.1080/10448632.2018.1514200 To link to this article: https://doi.org/10.1080/10448632.2018.1514200 Published online: 10 Oct 2018. Submit your article to this journal Article views: 9 View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=gnnw20 News and Reports Canada’s Neutron Source, the NRU reactor, closes anada has been a leader in neu- 500 million patients around the world tron radiograph was taken that cap- tron scattering for 70 years, start- over its lifetime. tured the last neutrons exiting the re- Cing with the National Research Ex- When the NRU reactor at AE- actor as it shut down (Figure 1). The perimental (NRX) reactor completed CL’s Chalk River Laboratories image was taken of a specially made by the National Research Council closed on March 31, 2018, it was the plaque, composed of layers of nickel (NRC) in 1947. Early neutron scat- world’s oldest major research reactor alloy plates and gadolinium lettering tering experiments were conducted (>5 MW) in the world. Since Febru- to create contrast. The neutron im- at NRX and then continued at the ary 2015, when the fi nal shutdown age shows a stylized layout of the six 10 times more powerful National of the NRU reactor was announced, neutron beamlines around the core Research Universal (NRU) reactor, the team at the neutron beam labo- of the NRU reactor, the biological with a fl ux of 3 × 1014 n/cm2/s. The ratory at NRU, known as the Cana- shield that protects personnel, and NRU reactor was completed in 1957 dian Neutron Beam Centre (CNBC), the graphite column (a further ex- by Atomic Energy of Canada Ltd. strived to extract as much value and planation of the image and how this (AECL), which was split off from the impact from the reactor as possible was done is provided at http://cins. NRC in 1952 to promote peaceful use in its fi nal years of operation. In ca/2018/05/30/the-fi nal-neutrons/). of nuclear energy. The NRU reactor other words, the goal was to ‘cross Most of these beamlines still per- was the primary facility for in-reactor the fi nish line running’, and that is formed among the best in the world, testing of nuclear components during what they achieved: all beamlines in terms of the quantity and quality the development of Canada’s fl eet were collecting data until the end, of output in science and engineering. of nuclear power stations. The NRU except one that had completed its fi - Among these high performers were reactor also produced radioisotopes nal measurements just hours before. a powder diffractometer, a polarized such as molybdenum-99, which have During the last minutes of the triple-axis spectrometer, a neutron been used to diagnose an estimated reactor’s operation, a memorial neu- refl ectometer and a stress mapping Figure 1. A neutron image of the plaque depicting the fi nal neutrons captured in the NRU reactor, overlaid with labels of each neutron beamline’s designation. (Image credit: CNBC). Neutron News Volume 29 • Number 2 • 2018 25 News and Reports supported by Walter ‘Walt’ J. Woy- towich (1949–53) as technical sup- port and Noel K. Pope (1950–53) in the Theoretical Physics Branch. Soon, scientists Dave G. Henshaw (1951–59), Alec Thomson Stew- art (1952–57), and John ‘Warwick’ Knowles (1954–56) were added to the Section. Together, the Section laid foundations for neutron scatter- ing experiments in gases, liquids and solids. Brockhouse took the lead on examining solids and the develop- ment of inelastic neutron scattering, which led to his Nobel Prize in 1994, after over 30 years from these pio- neering contributions. When Hurst left the Physics Di- vision in 1955, Brockhouse took Figure 2. Bert Brockhouse with the fi rst version of his triple-axis spectrometer for inelastic scat- over as Section Head, and Knowles tering at the NRU reactor (circa 1958–1959). (Image credit: AECL). moved on to do neutron nuclear physics soon after. In 1960, Neu- diffractometer. These beamlines the 1950s. Donald ‘Don’ G. Hurst tron Physics became a separate supported a strong community: over was Head of the Neutron Spectrom- branch of AECL headed by Brock- the last 5 years, about 800 research eters Section of the General Phys- house. In addition to neutron scat- participants from Canada and around ics Branch of NRC’s laboratories tering, the Branch included neutron the world, including students and re- in Chalk River, known in the late nuclear physicists, who used the searchers from universities, govern- ’40s as the Atomic Energy Project. NRX or NRU reactors as a neu- ment labs, and industry. Hurst was the inspiration behind the tron or gamma-ray source for other Over its lifetime, the neutron scat- neutron scattering program, work- methods including neutron-capture tering program at NRU made major ing with experimentalists Gertrude gamma-ray spectroscopy and posi- contributions to materials science ‘Trudi’ H. Goldschmidt (post-doc), tron annihilation. When Brockhouse and to neutron beam instrumenta- Andrew ‘Andy’ J. Pressesky, Philip left Chalk River in September 1962 tion. Innovative neutron instruments R. Tunnicliffe, and Norman Zinkan to become a professor at McMas- and methods developed in Canada Alcock, and theorist John Ashley ter University, Dave Woods took have been replicated at every ma- Spiers, to develop early neutron over the leadership of the Neutron jor neutron beam centre worldwide. spectrometers, take measurements Spectrometers Section. The Neutron These include Brockhouse’s triple- on gases, and solve the structure of Physics Branch was headed by Gil- axis spectrometer from the 1950s deuterated ammonium chloride. bert ‘Gil’ Alfred Bartholomew until (some shielding from the original in- These scientists each left Chalk 1971 (this was the only time the Sec- strument from the 1950s was still in River between 1949 and 1951, leav- tion Head responsible for neutron use on the E3 beamline at NRU) and ing Hurst and Bertram ‘Bert’ Nev- scattering was not also the Branch advances in neutron stress scanning ille Brockhouse (1950–62)1 as ex- Head). in the 1980s. perimentalists to carry forward the Throughout the 1960s, ’70s, and The neutron beam lab grew out development of neutron scattering, ’80s external researchers obtained of the pioneering efforts of scientists access to neutron beams primarily from NRC, and subsequently from 1Years indicate time associated with the by collaborating with Neutron Phys- AECL, from the late 1940s through neutron scattering lab unless otherwise noted. ics Branch scientists: A.D.B. ‘Dave’ 26 Volume 29 • Number 2 • 2018 Neutron News News and Reports Woods (1958–79, Section Head plishments include an extensive se- ment. Davis Earle and many other 1962–71, Branch Head 1971–79), ries of measurements on the inelastic AECL scientists and technical staff Gerald Dolling (1961–85, Branch neutron scattering from 4He by Dave contributed to the technical develop- Head 1979–85), Roger A. Cow- Woods and Eric Svensson. Woods ment of SNO into the ’90s, and the ley (1961–62, and 1964–70), Brian and Svensson demonstrated the exis- discoveries arising from it led to Mc- M. Powell (1964–98, Branch Head tence of a Bose-Einstein condensate Donald’s 2015 Nobel Prize in Phys- 1991–98), William ‘Bill’ J. L. Buy- in the superfl uid phase of liquid 4He ics as the leader of the SNO project. ers (1965–2007, Branch Head 1985– and measured precisely the associ- In addition, AECL nuclear fuel 91), C. Peter Martel (1965–93), Eric ated condensate fraction as a func- researchers operated a neutron im- C. Svensson (1966-2002), Thomas tion of temperature. Many of their aging beamline at the N1 beam ‘Tom’ M. Holden (1966–98), and measurements stood as the world port of the NRU reactor, as neu- Soo M. Kim (1970–97). There was standard for many years, and their tron imaging is uniquely powerful high turnover in the few technical measurements of the static struc- for non-destructive examination of staff positions that supported the ex- ture factor of liquid 4He remain the hydriding, a common cause of fuel periments in these years. Yet a few most accurate to date. With Robin failures. Under the direction of Alan served for signifi cant periods, includ- Armstrong from the University of Ross and then Glen MacGillivray, ing: Ed A. Glaser (1956–70), Har- Toronto, Bill Buyers experimentally N1 developed into a world-leading old F. Nieman (1964–94), Remick confi rmed the existence of the Hal- radiography facility in the ’80s. In ‘Rem’ S. Campbell (1967–78), Mel- dane Gap in 1985. This confi rmation 1994, AECL spun off this capability vin ‘Mel’ M. Potter (1968–10), Alan overturned the wisdom of the day and as a private business, Nray Services, H. Hewitt (1968–88), Don C. Ten- led to the acceptance of topological which was headed by MacGillivray nant (1971–97), and Jim C. Evans theory, for which Duncan Haldane and served the aerospace industry for (1979–86). shared the Nobel Prize in physics in inspection of turbine blades. Nray By the late ’70s, the Branch op- 2016, thereby opening the fi eld of to- immediately moved its operations erated several beamlines: triple-axis pological materials. The Branch also to the McMaster Nuclear Reactor, neutron spectrometers at the C4, C5, benefi ted from collaborations with where it still operates today.