Characterisation of the neutron field at the ANSTO instrument calibration facility

Simple item page
dc.contributor.authorMeriaty, Hen_AU
dc.date.accessioned2011-09-08T04:55:56Zen_AU
dc.date.available2011-09-08T04:55:56Zen_AU
dc.date.issued2009-12-01en_AU
dc.date.statistics2011-09-08en_AU
dc.description.abstractANSTO’s Instrument Calibration Facility (ICF) provides calibration services to radiation monitors, used in radiation protection applications. The facility has a large calibration room that accommodates the neutron source rig and the monitor table, which is remotely controlled. The room also hosts the gamma calibration services. Determination of the free field (direct) and scattered components of neutron field in a calibration room was essential to obtain an accurate response of the neutron monitor under testing. The free field fluence response and the fractional room return scatter, caused by the interaction of neutron fluence with the room structure, were determined. The fluence response was 1.210x10-4 μSv/h per n/m2; and the neutron field has a fractional room scatter of 0.044 at 1 m and increases linearly versus square of distance. The standard calibration methods, described by ISO-10647, IAEA-TR285, NCRP-112 and NPL-RS(EXT)5, were utilized in this characterisation and gave comparable results. The shadow-shield (truncated cone) were found more suitable to describe the neutron field compared with the other methods e.g. the polynomial fitting, semi-empirical due to the fact of the size, shape of the ICF room and source/monitor positions. Nevertheless; all methods resulted in good response curves with correlation coefficients of fitting greater than 0.97. The shadow shield consisted of two stacked conical sections. The first section was made from iron of 200mm height and the second section was a hollow and made from aluminium of 350mm height. The hollow section was then filled with neutron-moderating/absorbing materials i.e. water solution of LiBr 24% w/w. A performance test was conducted on the shield and gave a very satisfactory result e.g. the readings of fluence response to the free field neutron did follow the inverse square law with correlation >=0.999. It is worth noticing that at the completion of this characterisation and report, the calibration results with the Physikalische-Technische Bundesanstalt (PTB) in Germany became available. As a result, the neutron characterisation at ICF calibration room did agree with the BTP calibration within five percent. Consequently, the neutron field in ICF rig calibration room is now traceable to BTP standard laboratory in Germany. Also, this agreement confirms the integrity of the current neutron source e.g. anisotropy stability, which should save substantial cost and efforts in replacing the source or sending it overseas for re-certification.en_AU
dc.identifier.citationMeriaty, H. (2009). Characterisation of the neutron field at the ANSTO instrument calibration facility (ANSTO E-773). Lucas Heights, NSW: Australian Nuclear Science and Technology Organisation.en_AU
dc.identifier.govdoc3622en_AU
dc.identifier.isbn1921268123en_AU
dc.identifier.issn1030-7745en_AU
dc.identifier.placeofpublicationLucas Heights, New South Walesen_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/3718en_AU
dc.language.isoenen_AU
dc.publisherAustralian Nuclear Science and Technology Organisationen_AU
dc.relation.ispartofseriesANSTO External Reports;ANSTO-E-773en_AU
dc.subjectNeutron monitorsen_AU
dc.subjectBF3 countersen_AU
dc.subjectLong countersen_AU
dc.subjectRadiation monitoringen_AU
dc.subjectScatteringen_AU
dc.subjectCalibration standardsen_AU
dc.subjectInterlaboratory comparisonsen_AU
dc.titleCharacterisation of the neutron field at the ANSTO instrument calibration facilityen_AU
dc.typeExternal Reporten_AU
Files
Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
neutron-field-characterisation-ICF-07-sep-2011-library-final.pdf
Size:
2.46 MB
Format:
Adobe Portable Document Format
Description:
Download
License bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download
Collections
Scientific and Technical Reports