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Providing health physics and radiation protection services tools that are accurate, simple to operate and quick to setup is essential. Dose-rate monitoring is no exception.

Across day-to-day operations within the nuclear industry, police, fire and first responders in hazardous materials incidents, homeland security CBRN units responding to potentially radioactive threats, a sensitive gamma dose-rate monitor is a requirement. 

Either to search for ionising radiation sources or for the measurement of ambient dose-rate, a great device needs to be quick to setup and accurate. Ideally, it should also be able to make measurements from very low levels to the very high so you do not have to maintain, take, and monitor multiple devices when in the field.

That said, it is not often that a radiation detection technology ticking all the boxes hits the shelves. So, get ready for a unique and sophisticated gamma dose-rate monitor that can operates across a wide energy range, doesn’t need warm up, is extremely sensitive and is capable of making fast and accurate measurements. 

inTechBrew’s insight

John Caunt Scientific (JCS Nuclear Solutions), a UK-based company, has been designing and supplying nuclear radiation detection and measurement instrumentation for over 45 years. Since 1975, user defined requirements and early engagement with customers has successfully underpinned their development approach and has allowed them to provide unique measurement solutions across all nuclear sectors.

The GMS595, their newest wide-range gamma dose-rate monitor, has been developed in partnership with AWE (the UK Atomic Weapons Establishment) combines the measurement range of a suite of gas-filled detectors into a single hand-held instrument. It addresses some fundamental challenges in the world of radiation detection and measurement, providing data from a single device that is highly accurate, consistent across a wide temperature range and requires no time to stabilise.

At inTechBrew, we do like this new detector. Capable of accurately measuring dose-rates across a wide dose range, the GMS595 is simple to operate, quick to set up and environmentally stable. Developed for defence use and now the new standard gamma dose-rate instrument across sites at AWE, the GMS595 is a world-class monitor now available for use by organisations in policing and security and in a wide range of applications in the nuclear, health and radiation clean-up industries.

With a unique detector, back-end electronics and cutting-edge processing software, the GMS595 can make fast and accurate gamma dose-rate measurements from very low levels (nano Sieverts/hr) to the very high (1 Sievert/hr).

User case: Pulsed field shielding verification

Brighton, Sussex, 2022

In recent years, the importance of proper shielding in medical facilities has become increasingly apparent due to the growing reliance on advanced imaging techniques. 

Techniques such as PET/CT scanner, a non-invasive medical imaging tool, combine a positron emission tomography scanner and an X-ray computed tomography scanner. For PET, the patients are injected a radioactive tracer and are in fact the radiation source (emitting at 511 keV, which requires the lead chevon blocks in walls). The CT uses X-rays. Ensuring the safety of both patients and staff is a high priority, and it is crucial to effectively shield radiation. 

The Royal Sussex County Hospital’s £485 million 3Ts redevelopment program, focusing on Teaching, Trauma, and Tertiary care, provided an excellent opportunity for partner company Cerberus Nuclear to demonstrate the effectiveness of the JCS Nuclear Solutions GMS595 Wide Energy Range Gamma Monitor in conjunction with pulsed betatron sources (a typically compact doughnut-shaped chamber circulating an high-energy beam electrons such as in MRI devices, here replicated for the measurement by using a JME PXB2.5 portable betatron) for shielding verification.

Cerberus Nuclear was entrusted with the task of performing shield integrity testing at the Brighton 3Ts hospital. The project aimed to verify the proper installation of code lead and lead chevron block shielding in accordance with design specifications across five floors and 38 rooms, including lead-lined theatres, X-ray rooms, and PET rooms. This project highlights the significance of accurate shielding verification in ensuring the safety and wellbeing of patients and staff in medical facilities.

Approach and Methodology

To ensure a successful project outcome, Cerberus Nuclear began by completing radiation calculations and producing comprehensive safety documentation, including a method statement, risk assessment, and local rules. 

Over a two-week period, a team of four Cerberus Nuclear staff conducted shield integrity testing in 36 rooms using a sealed Se-75 source and 14 rooms with the JME betatron. The team systematically measured cold-side dose-rates for all walls, following a rigorous methodology to ensure accurate results. The recorded dose-rates were then compared to those calculated using MCNP to determine whether the walls were built as designed. This approach provided a detailed assessment of the shielding installations, helping to confirm their compliance with design specifications.

The GMS595

In the context of the Brighton 3Ts hospital project, the JCS GMS595 dose-rate gamma monitor was chosen as the primary instrument due to its exceptional features and capabilities, which provided a reliable and accurate solution for shielding verification in a complex construction environment.

The GMS595 provides the measurement range of a suite of gas-filled detectors all within a single hand-held instrument and allowed here to achieve accurate dose-rate measurements across a broad range, from nSv/hr to Sv/hr. The GMS595 also offers ease of operation, quick setup, and environmental stability, making it an ideal choice for work in the field.

The energy response of the GMS595 spans from 30keV to 7MeV, providing H*10 ambient dose equivalence. This wide energy response is crucial for the shielding verification process, as it ensures the detector can accurately measure various radiation types. The device is also temperature compensated and has an operating temperature range of 0°C to +40°C, ensuring reliable performance in various environmental conditions. Its warm-up time of no more than 10 seconds allows for quick deployment and efficient use on-site.

Performance, Results, and Conclusion

The GMS595, when paired with the JME PXB2.5 portable betatron, delivered outstanding performance, enabling accurate and efficient measurements for the thicker lead chevron block shielding of the PET rooms. The betatron pulsed 2.5MeV output was specifically configured for the work and provided a highly reliable and consistent output for all measurements.

The Cerberus Nuclear project team confirmed the findings from the shielding verification test performed in comprehensive report. The report demonstrated that effective shielding was in place, and the design intent was achieved, providing valuable insights into the success of the shielding installations. Due to the testing performed, the Brighton 3Ts project gained a high degree of confidence in the shielding installation. Thanks to the processes and procedures in place, the team involved in the project received no additional dose other than from background radiation, ensuring safety while delivering accurate and reliable results.

In conclusion, the GMS595, when combined with betatron pulsed devices, offers a reliable and accurate solution for shielding verification in highly shielded environments. This cutting-edge technology ensures that shielding installations are compliant with design specifications. The successful application of the GMS595 in the Brighton 3Ts hospital project demonstrates its value and effectiveness in the field, making it the primary choice for all future shielding verification work.

The GMS595 instrument used in this work was installed with the standard firmware. Since then, a new firmware version has been released, which further enhances the already impressive, pulsed field response by introducing dedicated pulsed field capability.

Thanks to Daniel Cork and the team at Cerberus Nuclear for their support and allowing JCS and inTechBrew to publish this case-study.

The technology: GMS595

ITEM	DATA
Range	<0.10μSvh⁻¹ to 999mSvh⁻¹
Energy Response	32keV (13% under response) to 7MeV
Dose Measurement Range	100nSv to better than 1.75Sv
Linearity	± 10%
Detector	Tissue Equivalent Plastic Scintillator
Response Time	2 seconds
Warm up time	No more than 10secs
Temperature Range	0°C to +40°C
Display	64×128 pixel LCD display. Single range in units of µSvh⁻¹
Power Requirements	2 x Industrial LR14 ‘C’ type alkaline cells
Battery Life	Over 50 hours
Weight	1.58 kg
Dimensions	L: 330mm x W: 90mm X H:145mm
Testing and Certification	EMC & Full Type Test supplied on request
Case inc. GMS595 & Batteries	4.6 kg
Case Dimensions	L:  410mm   W:  350mm     D: 200mm

Developed in partnership with AWE, the GMS595 wide-range gamma dose-rate monitor combines the measurement range of a suite of gas-filled detectors into a single hand-held instrument.

Capable of accurately measuring dose-rates from nSv/hr to Sv/hr, the GMS595 is simple to operate, quick to set up, environmentally stable and now the new standard gamma dose-rate instrument across site at AWE.

The GMS595 uses a unique detector, back-end electronics and cutting-edge processing software to make fast and accurate gamma dose-rate measurements from very low levels (nano Sieverts/hr) to the very high (1 Sievert/hr), providing an energy response from 32keV to 7meV.

Unlike conventional gas-filled detectors, the technology used in the GMS595 is not affected by temperature or pressure and does not need time to ‘warm up’. This cuts the time the operator has to wait for an effective detection capability from two minutes down to just two seconds. It also operates across a wide energy range, removing the need for the operator to maintain, take, and monitor multiple devices when in the field. 

It is worth here noting that AWE, a delivery partner for the UK’s nuclear deterrent programme, has been successfully using the GMS595 monitor as the new standard gamma dose-rate instrument for more than two years to ensure safe gamma levels are maintained across its sites. Similarly, a number of organisations could benefit from using the GMS595 over traditional gas-filled monitors, such as nuclear, police, fire and first responders in hazardous materials incidents. It could also potentially be used by CBRN units that respond to potentially radioactive threats.

Any questions ? Interested in another wide-Range, no warm up dose-rate monitoring? Do not hesitate to contact us directly, we will help you find a fit-for-purpose and cost-efficient wide-Range, no warm up dose-rate monitoring to answer your challenge.