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Prace nad paliwem do HTGR prowadzone w IBJ/ICHTJ

Nowicki Andrzej, Miśkiewicz Agnieszka, Kiegiel Katarzyna, Zakrzewska-Kołtuniewicz Grażyna

Postępy Techniki Jądrowej

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2024

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z. 2

18--22

PL

W ramach planowanego w latach 50. XX wieku programu pokojowego wykorzystania energii atomowej w Polsce ośrodek żerański IBJ miał zająć się zagadnieniami zaopatrzenia w paliwo planowanych do budowy reaktorów jądrowych. IBJ-Żerań prowadził m.in. badania nad metodami ekstrakcji uranu z ubogich rud uranowych i otrzymywania z nich ditlenku uranu. Równocześnie na Żeraniu pracowano nad metodami wytwarzania powłok węglowych na ziarnach sferycznych z tlenku glinu, co mogło stanowić wstęp do produkcji paliwa do reaktorów wysokotemperaturowych, tzw. TRISO. Koncepcję wytwarzania tego paliwa, rozwijaną w latach 60. ubiegłego wieku, zarzucono w późniejszym czasie. Na nowo odżyła ona na początku wieku XXI, a w ostatnim czasie uzyskała praktyczny wymiar w postaci projektu Gospostrateg i pomysłu budowy reaktora eksperymentalnego HTR w Świerku.

EN

As part of the program for the peaceful use of atomic energy in Poland planned in the 1950s, the Żerań IBJ center was to deal with the issue of fuel supply for the planned construction of nuclear reactors. IBJ-Żerań ran, among others, research on methods of extracting uranium from poor uranium ores and obtaining uranium dioxide from them. At the same time, Żerań was working on methods of producing carbon coatings on spherical grains made of aluminum oxide, which could be an introduction to the production of fuel for high-temperature reactors, the so-called TRISO. The concept of producing this fuel, developed in the 1960s, was later abandoned. It was revived at the beginning of the 21st century, and recently gained a practical dimension in the form of the Gospostrateg project and the idea of building an experimental HTR reactor in Świerk.

2

Ultrasonic Experimental Evaluation of the Numerical Model of the Internal Fluid Flow in the Kidney Cooling Jacket

Gambin Barbara, Korczak-Cegielska Ilona, Secomski Wojciech, Kruglenko Eleonora, Nowicki Andrzej

Archives of Acoustics

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2022

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Vol. 47, No. 3

389--397

EN

Kidney Cooling Jacket (KCJ) preserves the kidney graft, wrapped in the jacket, against the too fast time of temperature rise during the operation of connecting a cooled transplant to the patient’s bloodstream. The efficiency of KCJ depends on the stationarity of the fluid flow and its spatial uniformity. In this paper, the fluid velocity field inside the three different KCJ prototypes has been measured using the 20 MHz ultrasonic Doppler flowmeter. The simplified 2D geometrical model of the prototypes has been presented using COMSOL-Multiphysics to simulate the fluid flow assuming the laminar flow model. By comparing the numerical results with experimental data, the simplified 2D model is shown to be accurate enough to predict the flow distribution of the internal fluid velocity field within the KCJ. The discrepancy between the average velocity measured using the 20 MHz Doppler and numerical results was mainly related to the sensitivity of the velocity measurements to a change of the direction of the local fluid flow stream. Flux direction and average velocity were additionally confirmed by using commercial colour Doppler imaging scanner. The current approach showed nearly 90% agreement of the experimental results and numerical simulations. It was important for justifying the use of numerical modelling in designing the baffles distribution (internal walls in the flow space) for obtaining the most spatially uniform field of flow velocity.

3

Zaawansowane technologie detekcji promieniowania jonizującego w urządzeniach przenośnych

Nowicki Andrzej

Postępy Techniki Jądrowej

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2020

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z. 3

10--15

PL

Zasygnalizowano aktualne tendencje w konstrukcji przenośnych urządzeń do pomiaru promieniowania jonizującego pozwalające na miniaturyzację detektorów przy równoczesnym zwiększeniu ich możliwości pomiarowych. Przedstawiono kilka rozwiązań technicznych, w tym radiometru MKS-11GN SPECTRA ze względu na internetowe wzmianki o jego stosowaniu w Polsce.

EN

The current tendencies in the construction of portable counters for measuring ionizing radiation including miniaturization of detectors while increasing their measuring capabilities have been indicated. A number of technical solutions were presented, including the MKS-11GN SPECTRA radiometer due to its probably use in Poland.

4

Comparison of Acoustocerebrography Measurement and Magnetic Resonance Imaging Methods in the Assessment of White Matter Lesions in Patients with Atrial Fibrillation

Dobkowska-Chudon Wioletta, Wrobel Mirosław, Frankowska Emilia, Zegadlo Arkadiusz, Krupienicz Andrzej, Nowicki Andrzej, Olszewski Robert

Archives of Acoustics

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2020

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Vol. 45, No. 3

445--452

EN

The brain is subject to damage, due to ageing, physiological processes and/or disease. Some of the damage is acute in nature, such as strokes; some is more subtle, like white matter lesions. White matter lesions or hyperintensities (WMH) can be one of the first signs of micro brain damage. We implemented the Acoustocerebrography (ACG) as an easy to use method designed to capture differing states of human brain tissue and the respective changes. Aim: The purpose of the study is to compare the efficacy of ACG and Magnetic Resonance Imaging (MRI) to detect WMH in patients with clinically silent atrial fibrillation (AF). Methods and results: The study included 97 patients (age 66.26 ± 6.54 years) with AF. CHA2DS2-VASc score (2.5 ±1.3) and HAS BLED (1.65 ± 0.9). According to MRI data, the patients were assigned into four groups depending on the number of lesions: L0 – 0 to 4 lesions, L5 – 5 to 9 lesions, L10 – 10 to 29 lesions, and L30 – 30 or more lesions. Authors found that the ACG method clearly differentiates the groups L0 (with 0-4 lesions) and L30 (with more than 30 lesions) of WMH patients. Fisher’s Exact Test shows that this correlation is highly significant (p < 0.001). Conclusion: ACG is a new, easy and cost-effective method for detecting WMH in patients with atrial fibrillation. The ACG measurement methodology should become increasingly useful for the assessment of WMH.

5

Bezpieczeństwo badań ultrasonograficznych : wskaźniki termiczny i mechaniczny

Nowicki Andrzej

Inżynier i Fizyk Medyczny

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2019

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Vol. 8, nr 4

325--330

PL

W ciągu ostatnich kilku dziesięcioleci ultradźwięki znalazły szerokie zastosowanie w diagnostyce obrazowej. Ten artykuł przeglądowy omawia potencjalne efekty biologiczne związane z propagacją ultradźwięków w tkankach i podaje fizyczne podstawy wprowadzonych indeksów mechanicznego MI i termicznego TI zgodnych z Output Display Standard (ODS). W praktyce klinicznej otrzymywane wyniki są kompromisem pomiędzy jakością obrazu a możliwością systemu uzyskiwania zadowalających obrazów głęboko leżących struktur tkankowych – wyboru dokonuje się, biorąc pod uwagę minimalizację bioefektów. Moce wyjściowe ultrasonografów są regulowane i ograniczane do określonych poziomów. Bezpieczne dawki ultradźwiękowe wyznacza się według określonych zasad, a na ekranie wyświetlane są związane z nimi wielkości. Wielkości te określają możliwości wystąpienia zmian mechanicznych i termicznych w tkankach i dlatego mają znaczenia kliniczne. Wprowadzone wskaźniki – mechaniczny MI i termiczny TI uwzględniają fizyczny mechanizm oddziaływania między ultradźwiękami i biologiczną tkanką, który zależy od czasowych i przestrzennych parametrów pola akustycznego generowanego przez głowice ultradźwiękowe. Przewidywany wzrost temperatury określa się, stosując trzy różne modele tkankowe: homogeniczny, warstwowy i układ kość/tkanka.

EN

Ultrasounds have found widespread use in imaging diagnostics over the past few decades. This review article combines the reports on the biophysical effects and provides the rationale behind the mechanical index (MI) and thermal index TI complying with Output Display Standard (ODS). In clinical practice, the obtained diagnostic results are a compromise between the quality of the image and the possibility of a system of obtaining satisfactory images of deep-lying tissue structures – the choice is made taking into account the minimization of bioeffects. The output powers of ultrasonographs are regulated and limited to specific levels. Safe ultrasonic doses are determined according to specific rules, and the screen displays the associated quantities. These quantities determine the possibility of mechanical and thermal changes in the tissues and therefore have clinical significance. The introduced indexes MI and TI take into account the physical mechanism of interaction between ultrasounds and biological tissue, which depends on the temporal and spatial parameters of the acoustic field generated by ultrasound transducers. The predicted temperature increase is determined using three different tissue models: homogeneous, layered and bone/tissue interface.

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Assessment of High Frequency Imaging and Doppler System for the Measurements of the Radial Artery Flow-Mediated Dilation

Nowicki Andrzej, Gambin Barbara, Secomski Wojciech, Trawiński Zbigniew, Szubielski Michał, Tymkiewicz Ryszard, Olszewski Robert

Archives of Acoustics

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2019

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Vol. 44, No. 4

637--644

EN

Objectives: In the article we describe the new, high frequency, 20 MHz scanning/Doppler probe designed to measure the flow mediated dilation (FMD) and shear rate (SR) close to the radial artery wall. Methods: We compare two US scanning systems, standard vascular modality working below 12 MHz and high frequency 20 MHz system designed for FMD and SR measurements. Axial resolutions of both systems were compared by imaging of two closely spaced food plastic foils immersed in water and by measuring systolic/diastolic diameter changes in the radial artery. The sensitivities of Doppler modalities were also determined. The diagnostic potential of a high frequency system in measurements of FMD and SR was studied in vivo, in two groups of subjects, 12 healthy volunteers and 14 patients with stable coronary artery disease (CAD). Results: Over three times better axial resolution was demonstrated for a high frequency system. Also, the sensitivity of the external single transducer 20 MHz pulse Doppler proved to be over 20 dB better (in terms of a signal-to-noise ratio) than the pulse Doppler incorporated into the linear array. Statistically significant differences in FMD and FMD/SR values for healthy volunteers and CAD patients were confirmed, p-values < 0:05. The areas under Receiver Operating Characteristic (ROC) curves for FMD and FMD/SR for the prediction CAD had the values of 0.99 and 0.97, respectively. Conclusions: These results justify the usefulness of the designed high-frequency scanning system to determine the FMD and SR in the radial artery as predictors of coronary arterial disease.