About

Craig Marianno is an Associate Professor in the Department of Nuclear Engineering at Texas A&M University and serves as the Deputy Director of the Center for Nuclear Security Science and Policy Initiatives (NSSPI). His educational background includes a Ph.D. in Radiation Health Physics from Oregon State University, a Master of Science in Radiation Health Sciences from Colorado State University, and a Bachelor of Science in Physics from the University of California at Davis. His research interests encompass nuclear counter terrorism, nuclear instrumentation development, exercise development, radiological consequence management, and environmental health physics. He is actively involved in groups focused on nuclear security and nonproliferation, health physics, radiation biology, and medical physics, contributing to the advancement of safety and security in nuclear science.

Research topics

• Physics
• Nuclear physics
• Optics
• Materials science
• Radiochemistry
• Chemistry
• Optoelectronics

Selected publications

• The Rhisotope project: using radiation for conservation

  Scientific Reports · 2026-04-15

  articleOpen access

  The illegal poaching of rhinoceros for their horns continues to threaten the survival of the species despite ongoing conservation efforts. As black-market demand grows, poaching and smuggling methods have become more advanced, outpacing the effectiveness of current strategies. In response, the Rhisotope Project proposes a novel deterrent: the implantation of low-activity radioactive sources into rhinoceros’ horns to exploit the public fear of radiation and improve horn detection at borders. This research shows that radioactive horn implantation poses minimal risk to the animals’ health and that the probability of radiation-induced harm is significantly lower than the likelihood of being poached. Measurements collected from 16 white rhinoceroses six months post-implantation revealed no adverse biological effects, and all recorded dose rates remained below deterministic thresholds. These findings support both the safety and feasibility of the approach. Radiation inclusion in the horns could decrease poaching risk, improve seizure rates, and support rhinoceros population survival. This method may also serve as a reference point for safe radiation application in the other four rhinoceros’ species. Additionally, the concept could extend to other endangered fauna and flora. This innovative approach shows the ethical and practical utilization of radiation-based anti-poaching measures, contributing to conservation efforts.

  PublisherDOI

• Assessment of potential proliferation risk of small modular reactors: Case study of Ghana and Nigeria

  Journal of Radiation Research and Applied Sciences · 2025-10-04 · 1 citations

  articleOpen access

  The growing energy demand in Sub-Saharan Africa, particularly for essential services like hospitals and schools has renewed interest in clean and reliable sources such as Small Modular Reactors (SMRs). This study assesses the proliferation risks associated with SMR deployment in Ghana and Nigeria. An analytical model was used to estimate the number of NuScale SMRs needed to meet projected energy demands of 18 for Ghana and 43 for Nigeria. MCNP simulations were conducted to quantify the Pu and U-235 in spent fuel of NuScale and AP-1000 reactors. Results show that the operation of SMRs in Ghana would accumulate 6.6 SQ of U-235 and 51.5 SQ of Pu per year, while 15.7 SQ of U-235 and 123.1 SQ of Pu per year would be accumulated in Nigeria. Political factors were analyzed for each country based on variables that can influence nuclear proliferation. Overall, the technical and political assessments indicate a minimal risk for Ghana and a moderate for Nigeria. These findings highlight the necessity of aligning technical deployment with strong political and regulatory safeguards to ensure secure and responsible nuclear energy adoption.

  PublisherDOI

• Choosing the right reactor technology: A key step to strengthen nuclear security in West Africa’s nuclear energy plans

  Annals of Nuclear Energy · 2025-09-06

  article
  PublisherDOI

• Assessment of Potential Proliferation Risk of Small Modular Reactors: Case Study of Ghana and Nigeria

  SSRN Electronic Journal · 2025-01-01

  preprintOpen access
  PublisherDOI

• Special Nuclear Material Mass Estimates from Neutron Singles Count Rate [Poster]

  2025-07-21

  reportOpen access

  The objective of this research was to create an algorithm to provide an estimate of special nuclear material (SNM) mass using only neutron count rate data from a Radioisotope Identification Device (RIID), rather than using time-correlated data from a neutron multiplicity counter. To meet this objective neutron count rate measurements of a 252 Cf source were taken at varying distances with an ORTEC Detective X, FLIR Identifinder 2, and an ORTEC RADEAGLET-R. An algorithm was created to estimate mass of SNM utilizing the singles rate equation and the measured absolute efficiency curves.

  PublisherOA PDFDOI

• Preliminary Study of Dose Rates to Rhinoceros Basal Cells from a Radioactive Source to Deter Poaching

  Health Physics · 2025-03-19 · 1 citations

  article

  ABSTRACT: The five populations of rhinoceros species have declined in the wild due to poaching and habitat degradation, with demand for rhinoceros horn driving the poaching industry. The poaching of rhinoceros horn has critically threatened the conservation status of over half of these animals in the world today. To combat this threat and safeguard the species, a method involving the insertion of a radiation source into the rhinoceros's horn has been proposed. This approach aims to deter poachers due to public fear of radiation and enable the detection of smuggled horns based on the source's radioactive properties. To determine the health risks to the rhinoceros, this study presents the dose rate response functions to the rhino's epithelial basal stem cells that form the horn. The assessed responses assumed a modeled source centered at 10 and 20 cm above the basal stem cells. To identify the most appropriate source, dose rates were produced from gamma sources ranging from 0.1 to 2 MeV. Using numerical calculations, conservative dose rate estimates were determined as a function of energy and normalized to source activity, providing a foundation for computational results using Monte Carlo N-Particle Code version 6.2. With the dose rate responses as a function of energy and activity, the risk of deterministic and stochastic effects in this most at-risk tissue were understood based on the skin dose limitations for preventing deterministic effects to the rhinoceros.

  PublisherDOI

• Monte Carlo Simulations of Spent Nuclear Fuel Dry Storage Cask Measurements with a New External Remote Monitoring System for Developing Safeguards Approaches

  Nuclear Technology · 2024-09-20

  article
  PublisherDOI

• High Energy Gamma Radiation Induced by Fast Neutrons from Californium Source in NaI(Tl) Detector in Close Geometry Measurements

  2023-05-24

  articleSenior author

  A paper deals with the measurement of the effect of fast neutrons from the Cf-252 neutron source on the muon background detection with the NaI(Tl) scintillation detector. Previous research at TAMU has shown a possibility to measure high-energy cosmic ray particles, or secondarily produced muons, to predict the natural neutron background in the search for artificial neutron sources by mobile systems. One of the problems encountered in testing with Cf-252 was the increased contribution of high-energy gamma rays at small distances between the neutron source and the detector, which affects muon measurements. A primary source of a prompt gamma radiation, was found in the capsule of neutron source and AmBe material itself. More gamma photons are produced by neutrons in the detector crystal. If there is a moderator between the source and the detector, the contribution of this radiation increases due to neutron capture reactions. For higher neutron energies are crucial inelastic scattering, proton emission, alpha particle emission or multiple neutron emission accompanied by prompt gamma emission. On the other hand, experiments have not confirmed the effect of a steel plate between the detector and the neutron source. The solution may be to increase the lower discrimination during measurement with NaI(Tl) or to analyze the region between 8–14 MeV for the unusual increase in the number of pulses.

  PublisherDOI

• Radiation Detection for Border Monitoring

  Oxford University Press eBooks · 2023-06-20

  book-chapter1st authorCorresponding

  Abstract Since 1993, the International Atomic Energy Agency (IAEA) has tracked reported incidents of illicit radioactive material trafficking in their Incident and Trafficking Database. Between 1993 and 2021 there have been 320 recorded incidents of malicious trafficking that included industrial radioactive sources, special nuclear material, and scam/fraudulent material. In order to detect and intercept the illicit movement of radioactive material, countries have developed radiation detection regimes at border crossings and at ports of entry. The chapter discusses the key concepts behind radiation detection at borders, highlighting the commonly deployed defence-in-depth security strategy that utilizes multiple different types of detectors. These detection systems range in size from large, fixed-location radiation portal monitors (RPMs) to hand-held instruments such as personal radiation detectors and radioisotope identification devices. Typically, RPMs monitor moving vehicular and pedestrian traffic and the hand-held systems are employed to isolate and identify radioactive sources registered by the larger systems. With a properly trained force, these radiation detection systems can be effective at detecting the illicit transport of radioactive material across points of entry at borders.

  PublisherDOI

• A simple and low-cost directional detection technique for radiation source localization for nuclear security applications

  Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment · 2023-02-10 · 4 citations

  article
  PublisherDOI

Frequent coauthors

• Jennifer Erchinger

  Sandia National Laboratories

  28 shared

• J. Wagner

  United States Department of Energy

  19 shared

• Gene Kallenbach

  14 shared

• William Charlton

  11 shared

• Sunil S. Chirayath

  Texas A&M University

  11 shared

• Gentry C. Hearn

  SUNY Upstate Medical University

  10 shared

• J. TREVINO

  Texas A&M University

  10 shared

• Matt Grypp

  Texas Department of State Health Services

  9 shared