On the technical aspects of the NTHU reactor training course

Uncategorised 2 August 2025

This blog post is the final part of a series detailing this trip. This post was contributed to by Inez Solomon, Jack Woodward, and Christopher Barnes

The GREEN CDT trip to NTHU, Taiwan, to complete their Reactor and Radiation Training Programme, was split, as one might expect, into 2 clearly distinct areas – radiation detection systems, and reactor operation and training. In this blog, we’ll talk about the training itself, and what we learned about radiation detection, reactor operation, and the practical applications for both that happen at NTHU.

The radiation detection element of the course took a very analogue approach to detector systems that highlighted the importance of the various phases of signal processing necessary for each type of system. We were able to use a range of detectors, from simple counting detectors like a GM tube, to NaI scintillation and HPGe semiconductor detectors with varying energy resolutions, plus a couple of varieties of neutron detectors. Getting hands on, and physically moving cables between the various modules, including the pre-amplifier, amplifier, pulse shaper and SCA/MCA, and seeing the signal changes on an oscilloscope or even using an analogue electrical pulser to simulate a signal through the system, helped develop an appreciation for what each individual part of the system is doing, and through that, an understanding of how the overall detector system works.

One of the highlights of the NTHU Reactor Training course was the chance to operate the THOR research reactor. The reactor itself was impressive, with a walkway leading to it from the control room. Below us, submerged 20 meters in the coolant pond, we could see the reactor core. When powered up, the blue glow of Cherenkov radiation was a remarkable sight.

The reactor isn’t intended for power generation but is instead designed to be incredibly safe. The TRIGA UZrH fuel rods have a large negative temperature coefficient, meaning as the temperature rises, the core reactivity decreases, preventing overheating. Even during high-power operation, the water surrounding the core stays close to room temperature.

A key highlight was conducting an experiment to calibrate the reactor’s control blades. By slowly lowering each blade and measuring the response in power, we were taught how to determine each blade’s “reactivity worth,” which changes over the reactor’s lifetime.

NTHU is one of a select few facilities in the world that can offer a unique form of external beam therapy,  boron neutron capture therapy (BNCT). Whilst not strictly part of our training it was amazing to spend half a day getting a tour of the facility and getting to ask questions of the experts at NTHU. BNCT is particularly effective at treating recurrent head or neck cancers and this treatment can be a ‘hail mary’ for many patients. Since receiving medical device classification the Tsing Hua Open-pool Reactor (THOR) at NTHU has ensured treatments for current and future patients. BNCT is different to other forms of external beam therapies as it utilises nuclear reactions to achieve a localised and concentrated dose to tumors. The nuclear reaction in question is,

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In this process, boron is administered to the patient through a drug that preferentially accumulates in cancerous cells. When the tumor cells are exposed to neutrons from the reactor, the boron captures these neutrons, triggering a nuclear reaction that produces alpha particles. These alpha particles cause significant damage, but due to their short range, the radiation is localized to the tumor, minimizing damage to surrounding healthy tissues.

NTHU’s BNCT treatments have yielded impressive results, providing new hope for patients who might otherwise face terminal diagnoses. The success of THOR demonstrates the power of scientific innovation to improve patient outcomes, showcasing the potential for nuclear technology to benefit the general public.