{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,1]],"date-time":"2026-02-01T07:11:02Z","timestamp":1769929862268,"version":"3.49.0"},"reference-count":36,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2019,6,18]],"date-time":"2019-06-18T00:00:00Z","timestamp":1560816000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Engineering and Physical Sciences Research Council and Nuclear Decommissioning Authority, UK","award":["EP\/N509231\/1"],"award-info":[{"award-number":["EP\/N509231\/1"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The characterisation of buried radioactive wastes is challenging because they are not readily accessible. Therefore, this study reports on the development of a method for integrating ground-penetrating radar (GPR) and gamma-ray detector measurements for nonintrusive characterisation of buried radioactive objects. The method makes use of the density relationship between soil permittivity models and the flux measured by gamma ray detectors to estimate the soil density, depth and radius of a disk-shaped buried radioactive object simultaneously. The method was validated using numerical simulations with experimentally-validated gamma-ray detector and GPR antenna models. The results showed that the method can simultaneously retrieve the soil density, depth and radius of disk-shaped radioactive objects buried in soil of varying conditions with a relative error of less than 10%. This result will enable the development of an integrated GPR and gamma ray detector tool for rapid characterisation of buried radioactive objects encountered during monitoring and decontamination of nuclear sites and facilities.<\/jats:p>","DOI":"10.3390\/s19122743","type":"journal-article","created":{"date-parts":[[2019,6,19]],"date-time":"2019-06-19T10:43:32Z","timestamp":1560941012000},"page":"2743","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Integration of Ground- Penetrating Radar and Gamma-Ray Detectors for Nonintrusive Characterisation of Buried Radioactive Objects"],"prefix":"10.3390","volume":"19","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7536-7777","authenticated-orcid":false,"given":"Ikechukwu K.","family":"Ukaegbu","sequence":"first","affiliation":[{"name":"Engineering Department, Lancaster University, Lancaster LA1 4YW, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4832-3373","authenticated-orcid":false,"given":"Kelum A. A.","family":"Gamage","sequence":"additional","affiliation":[{"name":"School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7697-5889","authenticated-orcid":false,"given":"Michael D.","family":"Aspinall","sequence":"additional","affiliation":[{"name":"Engineering Department, Lancaster University, Lancaster LA1 4YW, UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,6,18]]},"reference":[{"key":"ref_1","unstructured":"Popp, A., Ardouin, C., Alexander, M., Blackley, R., and Murray, A. (2012, January 13\u201318). Improvement of a high risk category source buried in the grounds of a hospital in Cambodia. Proceedings of the 13th International Congress of the International Radiation Protection Association, Glasgow, UK."},{"key":"ref_2","unstructured":"IAEA (2014). Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards, International Atomic Energy Agency. Technical Report GSR Part 3."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"93","DOI":"10.1016\/S0265-931X(02)00041-3","article-title":"Properties, use and health effects of depleted uranium","volume":"64","author":"Bleise","year":"2003","journal-title":"J. Environ. Radioact."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"1006","DOI":"10.1080\/00223131.2014.915769","article-title":"Distribution of radioactive nuclides of boring core samples extracted from concrete structures of reactor buildings in the Fukushima Daiichi Nuclear Power Plant","volume":"51","author":"Maeda","year":"2014","journal-title":"J. Nucl. Sci. Technol."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"130","DOI":"10.1016\/j.jenvrad.2014.11.011","article-title":"Development of a neural network approach to characterise226Ra contamination at legacy sites using gamma-ray spectra taken from boreholes","volume":"140","author":"Varley","year":"2015","journal-title":"J. Environ. Radioact."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"957","DOI":"10.1016\/j.scitotenv.2017.06.067","article-title":"An in situ method for the high resolution mapping of137Cs and estimation of vertical depth penetration in a highly contaminated environment","volume":"605\u2013606","author":"Varley","year":"2017","journal-title":"Sci. Total Environ."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1016\/j.envpol.2018.04.112","article-title":"Reconstructing the deposition environment and long-term fate of Chernobyl137Cs at the floodplain scale through mobile gamma spectrometry","volume":"240","author":"Varley","year":"2018","journal-title":"Environ. Pollut."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"2752","DOI":"10.1109\/TNS.2009.2038480","article-title":"Depth determination of buried caesium-137 and cobalt-60 sources using scatter peak data","volume":"57","author":"Adams","year":"2010","journal-title":"IEEE Trans. Nucl. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"295","DOI":"10.1016\/j.nima.2016.03.098","article-title":"Novel methods for estimating 3D distributions of radioactive isotopes in materials","volume":"831","author":"Iwamoto","year":"2016","journal-title":"Nucl. Instrum. Methods Phys. Res. Sec. A"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"8262","DOI":"10.1021\/es201619r","article-title":"Determination of the depth of localized radioactive contamination by 137Cs and 60Co in sand with principal component analysis","volume":"45","author":"Adams","year":"2011","journal-title":"Environ. Sci. Technol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1150","DOI":"10.1016\/j.apradiso.2011.11.033","article-title":"Depth profiling 137Cs and 60Co non-intrusively for a suite of industrial shielding materials and at depths beyond 50 mm","volume":"70","author":"Adams","year":"2012","journal-title":"Appl. Radiat. Isot."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1448","DOI":"10.1109\/TNS.2012.2189128","article-title":"The advancement of a technique using principal component analysis for the non-intrusive depth profiling of radioactive contamination","volume":"59","author":"Adams","year":"2012","journal-title":"IEEE Trans. Nucl. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"270","DOI":"10.1016\/j.scitotenv.2015.03.131","article-title":"Remediating radium contaminated legacy sites: Advances made through machine learning in routine monitoring of \u201chot\u201d particles","volume":"521\u2013522","author":"Varley","year":"2015","journal-title":"Sci. Total Environ."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1016\/j.scitotenv.2015.10.112","article-title":"Mapping the spatial distribution and activity of 226Ra at legacy sites through Machine Learning interpretation of gamma-ray spectrometry data","volume":"545\u2013546","author":"Varley","year":"2016","journal-title":"Sci. Total Environ."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"631","DOI":"10.1016\/j.apradiso.2009.09.046","article-title":"Profiling the depth of caesium-137 contamination in concrete via a relative linear attenuation model","volume":"68","author":"Shippen","year":"2010","journal-title":"Appl. Radiat. Isot."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/j.jenvrad.2013.10.025","article-title":"Determination of 226Ra contamination depth in soil using the multiple photopeaks method","volume":"128","author":"Haddad","year":"2014","journal-title":"J. Environ. Radioact."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"393","DOI":"10.1016\/S0168-9002(01)00449-1","article-title":"An improved in situ method for determining depth distributions of gamma-ray emitting radionuclides","volume":"463","author":"Benke","year":"2001","journal-title":"Nucl. Instrum. Methods in Phy. Res. Sect. A"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"581","DOI":"10.1016\/j.jenvrad.2011.03.006","article-title":"A method for determining the analytical form of a radionuclide depth distribution using multiple gamma spectrometry measurements","volume":"102","author":"Dewey","year":"2011","journal-title":"J. Environ. Radioact."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"790","DOI":"10.1016\/j.apradiso.2011.01.019","article-title":"Simulation of a method for determining one-dimensional137Cs distribution using multiple gamma spectroscopic measurements with an adjustable cylindrical collimator and center shield","volume":"69","author":"Whetstone","year":"2011","journal-title":"Appl. Radiat. Isot."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"657","DOI":"10.1097\/HP.0b013e3181ca8ba8","article-title":"A numerical method for the calibration of in situ gamma ray spectroscopy systems","volume":"98","author":"Dewey","year":"2010","journal-title":"Health Phys."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"715","DOI":"10.1111\/j.1365-2478.2008.00724.x","article-title":"Effective permittivity of porous media: A critical analysis of the complex refractive index model","volume":"56","author":"Brovelli","year":"2008","journal-title":"Geophys. Prospect."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"7","DOI":"10.3390\/rs11020141","article-title":"Nonintrusive depth estimation of buried radioactive wastes using ground penetrating radar and a gamma ray detector","volume":"11","author":"Ukaegbu","year":"2019","journal-title":"Remote Sens."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"35","DOI":"10.1109\/TGRS.1985.289498","article-title":"Microwave Dielectric Behavior of Wet Soil-Part II: Dielectric Mixing Models","volume":"GE-23","author":"Dobson","year":"1985","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"803","DOI":"10.1109\/36.387598","article-title":"Dielectric Properties of Soils in the 0.3\u20131.3-GHz Range","volume":"33","author":"Peplinski","year":"1995","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1109\/TAP.1977.1141539","article-title":"An improved model for the dielectric constant of sea water at microwave frequencies","volume":"25","author":"Klein","year":"1977","journal-title":"IEEE Trans. Antennas and Propag."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1397","DOI":"10.1029\/RS005i012p01397","article-title":"The Brightness Temperature of a Vertically Structured Medium","volume":"5","author":"Stogryn","year":"1970","journal-title":"Radio Sci."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Ukaegbu, I.K., and Gamage, K.A.A. (2017). Ground Penetrating Radar as a Contextual Sensor for Multi-Sensor Radiological Characterisation. Sensors, 17.","DOI":"10.3390\/s17040790"},{"key":"ref_28","unstructured":"Pelowitz, D.B. (2011). MCNPX User\u2019s Manual: Version 2.7.0, Los Alamos National Laboratory."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"163","DOI":"10.1016\/j.cpc.2016.08.020","article-title":"gprMax: Open source software to simulate electromagnetic wave propagation for Ground Penetrating Radar","volume":"209","author":"Warren","year":"2016","journal-title":"Comput. Phys. Commun."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"G37","DOI":"10.1190\/1.3548506","article-title":"Creating finite-difference time-domain models of commercial ground-penetrating radar antennas using Taguchi\u2019s optimization method","volume":"76","author":"Warren","year":"2011","journal-title":"Geophysics"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1768","DOI":"10.1109\/TGRS.2018.2869027","article-title":"Realistic FDTD GPR Antenna Models Optimized Using a Novel Linear\/Nonlinear Full-Waveform Inversion","volume":"57","author":"Giannakis","year":"2019","journal-title":"IEEE Trans. Geosci. Remote Sens."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1016\/j.anucene.2018.04.028","article-title":"Activation product interpretation of structural material for fast critical assemblies","volume":"119","author":"Keith","year":"2018","journal-title":"Ann. Nucl. Energy"},{"key":"ref_33","doi-asserted-by":"crossref","unstructured":"Gamage, K.A.A., Joyce, M.J., and Taylor, G.C. (2011, January 6\u20139). A comparison of collimator geometries for imaging mixed radiation fields with fast liquid organic scintillators. Proceedings of the 2011 2nd International Conference on Advancements in Nuclear Instrumentation, Measurement Methods and their Applications, Ghent, Belgium.","DOI":"10.1109\/ANIMMA.2011.6172943"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"McConn, R., Gesh, C.J., Pagh, R., Rucker, R.A., and Williams, R. (2011). Compendium of Material Composition Data for Radiation Transport Modelling, Pacific Northwest National Laboratory. Technical report.","DOI":"10.2172\/1023125"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1922","DOI":"10.2136\/sssaj2000.6461922x","article-title":"A Pore Water Conductivity Sensor","volume":"64","author":"Hilhorst","year":"2000","journal-title":"Soil Sci. Soc. Am. J."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"135","DOI":"10.1016\/j.jappgeo.2015.03.009","article-title":"Improved estimation of soil clay content by the fusion of remote hyperspectral and proximal geophysical sensing","volume":"116","author":"Ciampalini","year":"2015","journal-title":"J. Appl. Geophys."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/12\/2743\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T12:59:26Z","timestamp":1760187566000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/19\/12\/2743"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2019,6,18]]},"references-count":36,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2019,6]]}},"alternative-id":["s19122743"],"URL":"https:\/\/doi.org\/10.3390\/s19122743","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2019,6,18]]}}}