* Corresponding author. Tel.: #31-224-565012; fax: #31- 224-561449. E-mail address: ohms@jrc.nl (C. Ohms) Physica B 276}278 (2000) 160}161 Neutron di!raction facilities at the high #ux reactor, Petten C. Ohms*, A.G. Youtsos, A. Bontenbal, F.M. Mulder JRC, P.O.Box 2, 1755ZG Petten, The Netherlands NRG, P.O.Box 1, 1755ZG Petten, The Netherlands IRI, Delft University of Technology, Mekelweg 15, 2629JB Delft, The Netherlands Abstract The High Flux Reactor in Petten is equipped with twelve beam tubes for the extraction of thermal neutrons for applications in materials and medical science. Beam tubes HB4 and HB5 are equipped with di!ractometers for residual stress and powder investigations. Recently at HB4 the Large Component Neutron Di!raction Facility has been installed. It is a unique facility with respect to its capability of handling heavy components up to 1000 kg in residual stress testing. Its basic features are described and the "rst applications on thick piping welds are shown. The di!ractometer at HB5 can be set up for powder and stress measurements. Recent applications include temperature dependent measurements on phase transitions in intermetallic compounds and on Li ion energy storage materials. 2000 Elsevier Science B.V. All rights reserved. Keywords: Residual stress; Powder di!ractometer; Welds; Magnetic transitions 1. The Large Component Neutron Di4raction Facility (LCNDF) In the process of upgrading the HFR neutron di!rac- tion facilities [1] it was decided to develop a new instru- ment for stress testing heavy structural components. Its objectives are mapping of residual stresses for adequate life assessment of components, and the micro-structural and residual stress characterization for adequate devel- opment of new composite materials. The LCNDF has become a unique European instrument in terms of its weight-handling capacity. The maximum translations are 400 mm horizontally (2) and 300 mm vertically with a spatial resolution of up to 0.01 mm. The full weight can be supported up to 300 mm o! the instrument central axis. This has been achieved through the physical separ- ation of the detector rotation axis (2) from the specimen rotation axis (). Applicable gauge sizes range from 1 mm to 2 cm. Since the LCNDF has been in operation two nuclear piping welds have been tested. Fig. 1 shows a thick- walled austenitic piping weld with a diameter of &430 mm and a weight of &350 kg on the facility. The tests have been performed mainly in the heat a!ected zone and some results are given in Ref. [2]. In a second campaign three-dimensional stress mapping has been performed across a bi-metallic ferritic-austenitic steel nu- clear piping weld. 2. The combined powder and stress di4ractometer at HB5 The di!ractometer operates at a wavelength of 0.258 nm and a #ux of 10 cms at the sample posi- tion. The angular resolution is 2"0.6 3 at 2"76 3 , and the 2 angular range is 5}1553. A cryostat with a three- stage closed cycle helium cooling system has been instal- led for temperatures between 3.6 K and room temper- ature. Ovens can be used for temperatures up to 1800 K. As an example of di!raction performed at HB5 a result is shown on the Li depleted spinel compound Li [Mn Li ]O that can act as cathode material in a charged Li battery. It was found to have a cubic structure down to temperatures of 4 K in contrast with 0921-4526/00/$ - see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 - 4 5 2 6 ( 9 9 ) 0 1 2 9 8 - 3