Authors : Cyril Cyrus Arwui; Henry Lawluvi; Nelson Agbemava; Etornam Ann Mensah; Emmanuel Akrobortu; Charles Kansaana

Volume/Issue : Volume 11 - 2026, Issue 4 - April

Google Scholar : https://tinyurl.com/4h7yb76k

DOI : https://doi.org/10.38124/ijisrt/26apr1020

Note : A published paper may take 4-5 working days from the publication date to appear in PlumX Metrics, Semantic Scholar, and ResearchGate.

Abstract : High-activity radioactive sources used in irradiation and industrial applications require physical protection systems (PPS) that can deter, detect, delay and enable response against theft, sabotage and insider-enabled removal. This paper examines PPS effectiveness for high-activity sealed radioactive sources through a socio-technical lens, using cobalt-60 facilities as a representative case. Drawing on international nuclear security guidance, the study integrates design basis threat concepts, performance-based PPS evaluation and human reliability analysis. A simple worked probabilistic model is used to compare two operating conditions: disciplined alarm handling and degraded performance characterized by alarm fatigue, poor communication and slower dispatch. The example shows that when sensor and transmission performance remain unchanged, deterioration in alarm assessment, communication reliability and response timing can reduce interruption probability from 0.578 to 0.150, representing a decline of about 74%. The analysis demonstrates that protection effectiveness is not determined by hardware alone; it depends on the interaction of technical layers, operator performance, organizational routines, insider threat controls and cyber-dependent support systems. The paper argues that regulators and operators should treat human reliability assurance, security culture and performance testing as core components of PPS design and oversight. This approach strengthens interruption capability and reduces the likelihood that high-activity radioactive sources become out of regulatory control.

Keywords : Physical Protection System; Human Reliability; Security Culture; Design Basis Threat; Insider Threat; Cobalt-60.

References :

1. International Atomic Energy Agency, “Nuclear Security Recommendations on Radioactive Material and Associated Facilities,” IAEA Nuclear Security Series No. 14, Vienna, 2011.
2. International Atomic Energy Agency, “Categorization of Radioactive Sources,” IAEA-TECDOC-1344, Vienna, 2003.
3. International Atomic Energy Agency, “Objective and Essential Elements of a State’s Nuclear Security Regime,” IAEA Nuclear Security Series No. 20, Vienna, 2013.
4. M. L. Garcia, The Design and Evaluation of Physical Protection Systems, 2nd ed. Burlington, MA: Butterworth-Heinemann, 2008.
5. International Atomic Energy Agency, “Nuclear Security Recommendations on Physical Protection of Nuclear Material and Nuclear Facilities (INFCIRC/225/Revision 5),” IAEA Nuclear Security Series No. 13, Vienna, 2011.
6. International Atomic Energy Agency, “Development, Use and Maintenance of the Design Basis Threat,” IAEA Nuclear Security Series No. 10, Vienna, 2009.
7. International Atomic Energy Agency, “Nuclear Security Culture,” IAEA Nuclear Security Series No. 7, Vienna, 2008.
8. International Atomic Energy Agency, “Preventive and Protective Measures against Insider Threats,” IAEA Nuclear Security Series No. 8, Vienna, 2008.
9. International Atomic Energy Agency, “Computer Security at Nuclear Facilities,” Vienna, 2011.
10. International Atomic Energy Agency, “Security of Radioactive Sources,” IAEA Nuclear Security Series No. 11, Vienna, 2009.
11. International Atomic Energy Agency, “Incident and Trafficking Database (ITDB) Fact Sheet,” Vienna, 2022.
12. J. Reason, Managing the Risks of Organizational Accidents. Aldershot: Ashgate, 1997.
13. U.S. Nuclear Regulatory Commission, Insider Mitigation Program Guidance, Washington, DC, 2013.
14. International Atomic Energy Agency, Computer Security Techniques for Nuclear Facilities, Vienna, 2020.
15. International Atomic Energy Agency, Security During the Lifetime of a Nuclear Facility, IAEA Nuclear Security Series No. 35-G, Vienna, 2018.
16. M. L. Garcia, Vulnerability Assessment of Physical Protection Systems. Sandia National Laboratories, 2006.