Engineering issues on the diagnostic port integration in ITER upper port 18

Pak, S.,Bertalot, L.,Cheon, M.S.,Giacomin, T.,Heemskerk, C.J.M.,Koning, J.F.,Lee, H.G.,Nemtcev, G.,Ronden, D.M.S.,Seon, C.R.,Udintsev, V.,Yukhnov, N.,Zvonkov, A. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1

The upper port #18 (UP18) in ITER hosts three diagnostic systems: the neutron activation system, the Vacuum Ultra-Violet spectrometer system, and the vertical neutron camera. These diagnostics are integrated into three infrastructures in the port: the upper port plug, interspace support structure and port cell support structure. The port integration in UP18 is at the preliminary design stage and the current design of the infrastructure as well as the diagnostic integration is described here. The engineering issues related to neutron shielding and maintenance are addressed and the design approach is suggested.

Growth and Differentiation of Circulating Stem Cells After Extensive Ex Vivo Expansion

Barbon Silvia,Rajendran Senthilkumar,Bertalot Thomas,Piccione Monica,Gasparella Marco,Parnigotto Pier Paolo,Di Liddo Rosa,Conconi Maria Teresa 한국조직공학과 재생의학회 2021 조직공학과 재생의학 Vol.18 No.3

Background: Stem cell therapy is gaining momentum as an effective treatment strategy for degenerative diseases. Adult stem cells isolated from various sources (i.e., cord blood, bone marrow, adipose tissue) are being considered as a realistic option due to their well-documented therapeutic potentials. Our previous studies standardized a method to isolate circulating multipotent cells (CMCs) that are able to sustain long term in vitro culture and differentiate towards mesodermal lineages. Methods: In this work, long-term cultures of CMCs were stimulated to study in vitro neuronal and myogenic differentiation. After induction, cells were analysed at different time points. Morphological studies were performed by scanning electron microscopy and specific neuronal and myogenic marker expression were evaluated using RT-PCR, flow cytometry and western blot. For myogenic plasticity study, CMCs were transplanted into in vivo model of chemically-induced muscle damage. Results: After neurogenic induction, CMCs showed characteristic dendrite-like morphology and expressed specific neuronal markers both at mRNA and protein level. The calcium flux activity of CMCs under stimulation with potassium chloride and the secretion of noradrenalin confirmed their ability to acquire a functional phenotype. In parallel, the myogenic potential of CMCs was confirmed by their ability to form syncytium-like structures in vitro and express myogenic markers both at early and late phases of differentiation. Interestingly, in a rat model of bupivacaine-induced muscle damage, CMCs integrated within the host tissue taking part in tissue repair. Conclusion: Overall, collected data demonstrated long-term cultured CMCs retain proliferative and differentiative potentials suggesting to be a good candidate for cell therapy. Background: Stem cell therapy is gaining momentum as an effective treatment strategy for degenerative diseases. Adult stem cells isolated from various sources (i.e., cord blood, bone marrow, adipose tissue) are being considered as a realistic option due to their well-documented therapeutic potentials. Our previous studies standardized a method to isolate circulating multipotent cells (CMCs) that are able to sustain long term in vitro culture and differentiate towards mesodermal lineages. Methods: In this work, long-term cultures of CMCs were stimulated to study in vitro neuronal and myogenic differentiation. After induction, cells were analysed at different time points. Morphological studies were performed by scanning electron microscopy and specific neuronal and myogenic marker expression were evaluated using RT-PCR, flow cytometry and western blot. For myogenic plasticity study, CMCs were transplanted into in vivo model of chemically-induced muscle damage. Results: After neurogenic induction, CMCs showed characteristic dendrite-like morphology and expressed specific neuronal markers both at mRNA and protein level. The calcium flux activity of CMCs under stimulation with potassium chloride and the secretion of noradrenalin confirmed their ability to acquire a functional phenotype. In parallel, the myogenic potential of CMCs was confirmed by their ability to form syncytium-like structures in vitro and express myogenic markers both at early and late phases of differentiation. Interestingly, in a rat model of bupivacaine-induced muscle damage, CMCs integrated within the host tissue taking part in tissue repair. Conclusion: Overall, collected data demonstrated long-term cultured CMCs retain proliferative and differentiative potentials suggesting to be a good candidate for cell therapy.

Evaluation of the Neutron Flux Effect on the ITER VUV Diagnostic System in the Upper Port

M. S. Cheon,S. Pak,C. R. Seon,H. G. Lee,L. Bertalot,R. Barnsley 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.3

Because of the harsh neutron environment of ITER, it is important to evaluate the neutron flux effect on the diagnostics, which will be installed near the plasma. A neutron transport analysis on the ITER upper port, which contains an optical system for the vacuum ultra-violet (VUV) spectrometer, is performed for this purpose. Neutron fluxes and spectra at various positions along the VUV optical path, and nuclear heating on the first mirror of the spectrometer are evaluated using the MCNP5 radiation transport code. MCAM, an interface program for the Monte Carlo code, has been used for the conversion of the 3-dimensional CAD model of the upper port plug, including diagnostic module, into the MCNP geometry model. A shutdown dose rate around the port interspace area is also evaluated using the direct-1-step (D1S) method. The result shows that active cooling of the first mirror is not necessary and that the calculated dose rate level satisfies the safety requirement of ITER.

Operational Radioactivity Evaluation of ITER Diagnostic Neutron Activation System

Cheon, M.S.,Seon, C.R.,Pak, S.,Lee, H.G.,Bertalot, L.,Forrest, R.A. IEEE 2010 IEEE transactions on plasma science Vol.38 No.3

<P>At the International Thermonuclear Experimental Reactor (ITER), a neutron activation system is foreseen to measure neutron fluence on the first wall and to evaluate total fusion power from ITER plasma. This system utilizes the method of counting gamma radiation from the metal sample irradiated by the neutron flux at the irradiation end located near the plasma. Evaluation of the operational radioactivity of the sample, which has been induced during ITER operation, is necessary in order to determine sample material, mass, and the appropriate irradiation time. Neutronic calculations are performed to evaluate operational activity of the sample. Activation of the sample is calculated according to the irradiation time for various sample materials such as Si, Al, Ti, Fe, Nb, and Cu and by assuming that the samples are irradiated at the midplane inboard region where the neutron flux is one of the strongest.</P>

Radiation shielding design evaluation for ITER VUV edge imaging spectrometer

An, YoungHwa,Seon, Changrae,Cheon, MunSeong,Pak, Sunil,Choi, Jihyun,Lee, Hyeon Gon,Bernascolle, Philippe,Barnsley, Robin,Bertalot, Luciano,Krasilnikov, Vitaly,Simrock, Stefan North-Holland 2017 Fusion engineering and design Vol.123 No.-

<P><B>Abstract</B></P> <P>The local radiation shielding design for the detector of ITER VUV edge imaging spectrometer is evaluated based on the MCNP calculation using a local port cell model of ITER upper port #18. A back-illuminated CCD (Charge-Coupled Device), the envisaged VUV (Vacuum Ultraviolet) detector for ITER VUV edge imaging spectrometer will be installed at ITER upper port #18 port cell region, in which a harsh radiation environment is expected with neutron flux higher than 10<SUP>5</SUP> neutronscm<SUP>−2</SUP> s<SUP>−1</SUP> mainly thermalized from d-t neutrons in plasma as well as high gamma ray dose of several tens kGy mainly from <SUP>16</SUP>N isotopes in water coolant. For the evaluation of the radiation exposure to the detector, the local port cell model is developed to reduce both the calculation time and statistical error. The boundary neutron source based on MCNP result using C-lite model as well as gamma source based on ITER radiation map has been utilized for the analysis of local port cell model. Since the radiation exposure to the back-illuminated CCD should be mitigated as much as possible to minimize the radiation damage to the detector as well as single event upset, local shielding design options for the VUV detector with various shapes, thicknesses, and material compositions are evaluated. The result shows that the neutron flux and gamma dose at the location of VUV detector can be mitigated below 100ncm<SUP>−2</SUP> s<SUP>−1</SUP> and 10Gy, respectively, which are the alert thresholds for non-critical electronics in ITER.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The radiation shielding design for ITER VUV edge imaging spectrometer is evaluated using MCNP with a local port cell model. </LI> <LI> The boundary neutron source from MCNP result of C-lite model and gamma source from ITER radiation map have been utilized. </LI> <LI> With proper shielding, radiation at VUV detector can be mitigated below alert threshold for non-critical electronics in ITER. </LI> </UL> </P>

Electromagnetic analysis for the in-vessel transfer lines of neutron activation system

Pak, Sunil,Cheon, Mun Seong,Seon, Chang Rae,An, Young Hwa,Choi, Jihyun,Lee, Hyeon Gon,Bertalot, Luciano,Vitaly, Krasilnikov Elsevier 2017 Fusion engineering and design Vol.124 No.-

<P><B>Abstract</B></P> <P>Neutron activation system is one of the neutron diagnostic systems in ITER which measures total neutron flux and first wall neutron fluence. This system has several pneumatic tubes installed on the vacuum vessel to deploy the irradiation samples near the plasma. The pneumatic tubes, called as <I>transfer lines,</I> get eddy current induced during plasma disruption, leading to Lorentz force by interacting the background magnetic field. This paper presents the electromagnetic (EM) loads on the in-vessel components of NAS for various disruption scenarios. The EM loads were calculated with the finite element solver, ANSYS-EMAG. It is proposed that the transfer lines are electrically insulated from the vacuum vessel in order to mitigate the excessively high EM loads. The analysis results showed that the electrical insulation reduces the load by one order of magnitude.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The electromagnetic (EM) load on the in-vessel transfer line of ITER neutron activation system is calculated. </LI> <LI> The EM load is caused mainly by creating a big eddy current loop together with the vacuum vessel. </LI> <LI> It is shown that electric insulation of the transfer line from the vacuum vessel can reduce the EM load drastically. </LI> </UL> </P>

Shutdown dose rate contribution from diagnostics in ITER upper port 18

Cheon, M.S.,Pak, S.,An, Y.H.,Seon, C.R.,Lee, H.G.,Bertalot, L.,Krasilnikov, V.,Zvonkov, A. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1

D-T operation of ITER plasma will produce high-energy fusion neutrons those can activate materials around the place where human-access is necessary. The interspace of the diagnostic port is one of the area where human-access is necessary for the maintenance of diagnostic systems installed at the port, so it is important to evaluate a dose rate of the interspace area in order to comply with ALARA principle. The shutdown dose rate (SDR) in the interspace of ITER upper port 18 was evaluated by the Direct 1-Step (D1S) method using MCNP5 code. This port contains three diagnostics: Vacuum Ultra-Violet (VUV) Spectrometer, Neutron Activation System (NAS), and Upper Vertical Neutron Camera (UVNC). The contribution of each diagnostic in the port was evaluated by running separate upper port MCNP models those contain individual diagnostic only, and the total dose rate contribution was evaluated with the model which was fully integrated with all the diagnostics. The effect of the opening around the upper port plug and of the other ports was also investigated. The purpose of this assessment is to provide the shielding design basis for the preliminary design of the diagnostic integration in the port. The method and result of the calculation will be presented in this paper.