What is NQL

What is Neutron Quality Label?

Neutron Quality Label (NQL) is a quality standard for residual stress analysis using neutron diffraction, following certain calibration guidelines and reporting requirements on the instrument. On strain scanners or measurements where the NQL is applied, one can ensure that the output of stress analysis is based on accurate measurement data, and any present anomalies is quantified and reported. NQL also standardized the reporting of the instrument calibration and configuration, enabling measurements to be reproduced in other neutron strain scanners, thus improving the interchangeability between instruments.

NQL is obtained by performing calibration measurements using a set of samples with specific geometries. This calibration is then reported in a standardized template which is attached to the residual stress analysis results. The calibration should be performed regularly according to the best practice of each instrument. More information about the calibration samples and measurements can be found on this page.

Currently there are four neutron strain scanners participating in the initiation and the application of NQL: ENGIN-X (ISIS, United Kingdom), MPISI (Necsa, South Africa), SALSA (ILL, France) and STRESS-SPEC (MLZ, Germany). More information about the participating strain scanners can be found on this page. Neutron strain scanners of other facilities are invited to contact any of the participating instruments to arrange the duplication of calibration samples, carry out the calibration protocol, and prepare the calibration report.

The full report of the pilot project on the NQL development is available in the deliverable D2.1 of the BrightnESS2 project available here [TODO link to BrightnESS2 d2.1 report?]. The NQL will be continuously maintained by its participants, with future suggestions and amendments to the calibration sample, protocol and reporting to be considered.