Dynamic Amplification Factor of the ITER Diagnostic Upper Port Plug

Pak, Sunil,Udintsev, Victor,Maquet, Philippe,Pitcher, Charles Spencer,Mun-Seong Cheon,Chang Rae Seon,Hyeon Gon Lee Institute of Electrical and Electronics Engineers 2014 IEEE transactions on plasma science Vol. No.

<P>The diagnostic upper port plug in ITER is a long metal box cantilevered to the vacuum vessel port with 42 × M52 studs and nuts. The plug structure has a heavy payload at the front, such as the diagnostic first wall and the diagnostic shield module to protect the diagnostic components from plasma and neutron fluxes. This kind of structural configuration is susceptible to a resonance with the transient external load. For the upper port plug, the design-driving load is electromagnetic (EM) forces due to plasma disruptions. In this paper, the dynamic amplification factor (DAF) of the structure is calculated for such EM loads. The bolted joint at the back flange of the plug structure is also considered together with the port extension of the vacuum vessel and its influence on the dynamic behavior is investigated. The analysis results show that the bolted joint reduces the DAF as well as the natural frequency of the structure.</P>

Fracture mechanics analysis approach to assess structural integrity of the first confinement boundaries in ITER Generic Upper Port Plug structure

Guirao, Julio,Iglesias, Silvia,Vacas, Christian,Udintsev, Victor,Pak, Sunil,Maquet, Philippe,Rodriguez, Eduardo,Roces, Jorge Elsevier 2015 Fusion engineering and design Vol.98 No.-

<P><B>Abstract</B></P> <P>This paper demonstrates structural integrity of the first confinement boundary in Generic Upper Port Plug structures against cracking during service. This constitutes part of the justification to demonstrate that the non-aggression to the confinement barrier requirement may be compatible with the absent of a specific in-service inspections (ISI) program in the trapezoidal section. Since the component will be subjected to 100% volumetric inspections it can be assumed that no defects below the threshold of applied Nondestructive Evaluation techniques will be present before its commissioning. Cracks during service would be associated to defects under Code acceptance limit. This limit can be reasonably taken as 2mm. Using elastic–plastic fracture mechanics an initial defect is postulated at the worst location in terms of probability and impact on the confinement boundary. Its evolution is simulated through finite element analysis and final dimension at the end of service is estimated. Applying the procedures in RCC-MR 2007 (App-16) the stability of the crack is assessed. As relative high safety margin was achieved, a complementary assessment postulating an initial defect of 6mm was also conducted. New margin calculated provides a more robust design.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A parametric submodel of the spot under study is developed. </LI> <LI> The associated macro has the capability to successively re-build the submodel implementing the crack with the geometry of the updated crack front as a function of the predicted increments of length in the apexes of the crack from the calculated stress intensity factor at the crack front. </LI> <LI> The analysis incorporates the crack behavior model to predict the evolution of the postulated defect under the application of the different transients. </LI> <LI> The analysis is based on the Elasto-Plastic Fracture Mechanics (EPFM) theory to account for the ductility of the materials (316LN type stainless steel). </LI> </UL> </P>

Numerical simulation of draining and drying procedure for the ITER Generic Equatorial Port Plug cooling system

Tanchuk, V.,Grigoriev, S.,Lyublin, B.,Maquet, P.,Senik, K.,Pak, S.,Udintsev, V. North-Holland ; Elsevier Science Ltd 2016 Fusion engineering and design Vol.109 No.1

For effective vacuum leak testing all cooling circuits serving the ITER vessel and in-vessel components shall be drained and dried so that after this procedure taking less than 100h the purge gas passing through a component has water content less than 100ppm. This process is four-stage, with the first stage using a short blast of compressed nitrogen to blow most of water in the coolant channels out of the circuit. This process is hindered by volumes which trap water due to gravity. To remove the trapped water, it is necessary, first, to heat up the structure by hot and compressed nitrogen, and then water is evaporated by depressurized nitrogen. The cooling system of the ITER Diagnostic Equatorial Port Plugs is of a complicated hydraulic configuration. The system branching might make difficult removal of water from the piping in the scheduled draining mode. The authors have proposed the KORSAR computation code to simulate draining of the GEPP cooling circuit. The numerical simulation performed has made it possible to describe the process dynamics during draining of the entire GEPP cooling circuit and to define the process time, amount and location of residual water and evolution of two-phase flow regime.

The choice of dynamic amplification factors for the ITER generic port plugs during disruptions

Vacas, Christian,Rodriguez, Eduardo,Guirao, Julio,Iglesias, Silvia,Udintsev, Victor,Pak, Sunil,Maquet, Philippe,Roces, Jorge,Casal, Natalia Elsevier 2015 Fusion engineering and design Vol.98 No.-

<P><B>Abstract</B></P> <P>The purpose of this paper is present an overview of the methodology followed to calculate the dynamic amplification factors applied to the electromagnetic loads acting in the ITER generic port plugs.</P> <P>The methodology used for combining an EM transient event with another kind of load is based in the treated of this dynamic EM event as a static load. As first stage a transient dynamic analysis was performed, at the most demanded electromagnetic event [2], to determine the dynamic response of the port plugs. In the same way, have been solved all the time steps of the dynamic event as static loads, it means that the inertial effect has been neglected. The response of each time-step at the dynamic solution has been compared with the same time-step solved as a static load. For this purpose some control points were positioned along the structure at the most representative locations. The key of these calculations is the understanding of the deformed modes affecting the port plug in order to obtain a reasonable dynamic amplification factors that permit the characterization of these loads in a realistic way and does not derive in a too conservative approach. Additionally, the fundamental frequencies and vibration modes of the generic port plug, requested for the characterization of the damping effects at the structure, were calculated in a complementary modal analysis performed for this aim.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dynamic amplification factor is largely influenced by the DFWs geometry and for the type of bond between DFW and DSM. </LI> <LI> DAF were calculated by analyzing the deformed shape and not just looking at the absolute values of displacements. </LI> <LI> Detailed transient time history non-linear analysis of an MDUP II electro magnetic event has been carried out. </LI> <LI> Cuasi-constant damping ratio of 3% has been considered using a generalized proportional damping model. </LI> </UL> </P>

Preliminary Design for Diagnostic Port Integration at ITER Upper Port #18

Pak, S.,An, Y. H.,Seon, C. S.,Choi, J. H.,Cheon, M. S.,Lee, H. G.,Udintsev, V.,Giacomin, T. Institute of Electrical and Electronics Engineers 2018 IEEE transactions on plasma science Vol. No.

<P>ITER has many ports to install various diagnostics which view and measure various plasma parameters. One of the ports, the upper port #18 (UP18) is designed to integrate three tenant diagnostic systems: vacuum ultraviolet spectrometer, neutron activation system, and upper vertical neutron camera. The key design drivers for the port integration are requirements on neutron shielding and maintenance. In this paper, we discuss the neutron shielding design made following the as low as reasonable achievable principle in order to reduce the shut-down dose rate in the interspace and port cell which are human-accessible areas. The design choice for radiation shielding of electronics in the port cell is also discussed. The port maintenance in ITER consists of remote handling operation for the port plug and manual (or assisted-manual) operation for the interspace and port cell areas. The compatibility with the ITER maintenance strategy is investigated for UP18 and the associated issues are addressed.</P>

Engineering requirements due to the ESP/ESPN regulation apply at the port plug for ITER diagnostic system

Giacomin, T.,Delhom, D.,Drevon, J.-M.,Guirao, J.,Iglesias, S.,Jourdan, T.,Loesser, D.,Maquet, P.,Ordieres, J.,Pak, S.,Proust, M.,Smith, M.,Udintsev, V.S.,Vacas, C.,Walsh, M.J.,Zhai, Y. Elsevier 2015 Fusion engineering and design Vol.98 No.-

<P><B>Abstract</B></P> <P>Due to this position close to the plasma, the port plug structure and the diagnostic first wall (DFW) contain water to allow cooling during operation and for heating during bake-out. To remove the heat coming from the plasma due to radiation and neutrons, the pressure inside these structures should be up to 44 bars. On the other hand, the dominant load expected to drive the design of these structures is of electromagnetic origin during the plasma disruption. Description of the loads acting on DFWs and generic port plug structures and the significance of the load due to the water pressure, with implications on the design and inspection, are discussed in this paper.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The ESP/ESPN regulation is applied to all equatorial and upper port-based diagnostic systems. </LI> <LI> The EPP and UPP structure provides a flexible platform for a variety of diagnostics. </LI> <LI> The EPP and UPP structure provide a support the diagnostic shielding module. </LI> </UL> </P>

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.