Computational analysis of the dose rates at JSI TRIGA reactor irradiation facilities

Ambrožič, Klemen; Žerovnik, Gašper; Snoj, Luka

doi:10.1016/j.apradiso.2017.09.022

Cited by 75 publications

(48 citation statements)

References 28 publications

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“…Chips were irradiated with neutrons in the TRIGA reactor in Ljubljana [24,25] to 1 MeV neutron equivalent fluences ranging from 1·10 13 n eq /cm 2 to 2·10 15 n eq /cm 2 . In the reactor, irradiation is performed by inserting the samples into the core through irradiation tubes.…”

Section: Samples and Irradiationmentioning

confidence: 99%

Charge-collection properties of irradiated depleted CMOS pixel test structures

Mandić

Cindro

Gorišek

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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Edge-TCT and charge collection measurements with passive test structures made in LFoundry 150 nm CMOS process on p-type substrate with initial resistivity of over 3 kΩcm are presented. Measurements were made before and after irradiation with reactor neutrons up to 2·10 15 n eq /cm 2 . Two sets of devices were investigated: unthinned (700 µm) with substrate biased through the implant on top and thinned (200 µm) with processed and metallised backplane. Depletion depth was estimated with Edge-TCT and collected charge was measured with 90 Sr source using an external amplifier with 25 ns shaping time. Depletion depth at given bias voltage decreased with increasing neutron fluence but it was still larger than 70 µm at 250 V after the highest fluence. After irradiation much higher collected charge was measured with thinned detectors with processed backplane although the same depletion depth was observed with Edge-TCT. Most probable value of collected charge of over 5000 electrons was measured also after irradiation to 2·10 15 n eq /cm 2 . This is sufficient to ensure successful operation of these detectors at the outer layer of the pixel detector in the ATLAS experiment at the upgraded HL-LHC.

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Section: Samples and Irradiationmentioning

confidence: 99%

Charge-collection properties of irradiated depleted CMOS pixel test structures

Mandić

Cindro

Gorišek

et al. 2018

Nuclear Instruments and Methods in Physics Research Section A:

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“…In order to prepare for the TLD irradiations, a comprehensive computational study of steady state neutron dose rate and prompt only gamma dose rate has been performed, to determine desired reactor power and irradiation time. Expected dose-rates were taken from [8]. For covering the desired measured dose range of 1 kGy to 100 kGy the F22 irradiation position, equipped with the pneumatic transfer system was selected and preliminary irradiations were performed.…”

Section: B Pre-experimental Preparationmentioning

confidence: 99%

“…radiation tolerance testing [2] and material sample irradiation [3]. Numerous activities for validation of the computational model such as reaction rate measurements [4], [5], neutron and gamma field measurements using fission and ionization chambers [6], [7] have led to a validated representative computational model, which has been used for a more rigorous characterization of a steady state radiation field inside its irradiation facilities [8], [9]. The next step is to capture temporally dependent radiation field behavior, especially gamma due to decay of activation and fission products, which amounts to up to 20 % to 30 % [10], depending on operational history and position inside the reactor core.…”

Section: Introductionmentioning

confidence: 99%

JSI TRIGA neutron and gamma field characterization by TLD measurements

Ambrožič

Malik²,

Obryk³

et al. 2020

EPJ Web Conf.

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A well characterized radiation field inside a research nuclear reactor irradiation facilities enables precise qualification of radiation effects to the irradiated samples such as nuclear heating or changes in their electrical or material properties. To support the increased utilization of the JSI TRIGA reactor irradiation facilities in the past few years mainly on account of testing novel detector designs, electronic components and material samples, we are working on increasing the neutron and gamma field characterization accuracy using various modeling and measurement techniques. In this paper we present the dose field measurements using thermo-luminescent detectors (TLD’s) with different sensitivities neutron and gamma sensitivities, along with multiple ionization and fission chamber. Experiment was performed in several steps from reactor start-up, steady operation and a rapid shutdown, during which the ionization and fission chamber signals were acquires continuously, while the TLD’s were being irradiated at different stages during reactor operation and after shutdown, to also capture response to delayed neutron and gamma field. The results presented in this paper serve for validation of JSI designed JSIR2S code for delayed radiation field determination, initial results of its application on the JSI TRIGA TLD measurements will also be presented.

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“…However this is not the case for γ-ray fields. Event though particle transport computer codes, such as Monte Carlo code MCNP support generation of neutron induced γ-rays, commonly only prompt γ-ray generation is supported by default [5]. Measurement with ionization chamber indicate that γ-ray fluxes due to decay of neutron activated isotopes (delayed γ-rays) contribute up to 30 % of total photon flux [6,7].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally these γ-ray fluxes are time dependent due to decay of fission and activation products and are also present after reactor shutdown. Up to date, only prompt γ fields have been characterized [5], with delayed part still to be evaluated. Two approaches in Monte Carlo particle transport for modeling delayed γ-rays, namely D1S [8] and R2S [9,10] are used.…”

Section: Introductionmentioning

confidence: 99%

Modeling of γ field around irradiated TRIGA fuel elements by R2S method

Ambrožič

Snoj

2017

EPJ Web Conf.

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Abstract. The JSI TRIGA reactor has several irradiation facilities with well characterized neutron fields. The characterization was performed by measurements and by utilizing Monte Carlo particle transport computational methods. Because of this, JSI TRIGA has become a reference center for neutron irradiation of detectors for ATLAS experiment (CERN). Thorough γ characterization of the reactor is however yet to be performed. Current Monte Carlo particle transport code only account for the prompt generation of neutron induced γ rays, which have been characterized, but are neglecting the time dependent delayed part, which may in some cases amount to more then 30 % of total γ flux in an operation reactor, and is the only source of γ-rays after reactor shutdown. Several common approaches of modeling delayed γ-rays , namely D1S and R2S exist. In this paper an in-house developed R2S method code is described, coupling a Monte Carlo particle transport code MCNP6 and neutron activation code FISPACT-II, with intermediate steps performed by custom Python scripts. An example of its capabilities is presented in terms of evaluation of utilization of JSI TRIGA nuclear fuel as a viable γ-ray source. In the model, fresh nuclear fuel is considered and a silicon pipe sample is modeled in. Fuel activities, dose and kerma rates on the sample, as well as emitted γ-ray spectra and isotopic contribution to the contact dose are calculated and presented.

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Computational analysis of the dose rates at JSI TRIGA reactor irradiation facilities

Cited by 75 publications

References 28 publications

Charge-collection properties of irradiated depleted CMOS pixel test structures

Charge-collection properties of irradiated depleted CMOS pixel test structures

JSI TRIGA neutron and gamma field characterization by TLD measurements

Modeling of γ field around irradiated TRIGA fuel elements by R2S method

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