Numerical analysis for heat transfer from a Cd poison in cryogenic hydrogen

Tatsumoto, Hideki; Kato, Takashi; Aso, Tomokazu; Hasegawa, Shoichi; Ushijima, Isamu*; Otsu, Kiichi*; Ikeda, Yujiro

LA-UR-06-3904, Vol.2, p.426 - 434, 2006/06

In JSNS, Cadmium has been selected as a poison material in a hydrogen moderator to obtain narrow neutron pulse. The concern to adopt to Cd is how to bond Cd and Al alloy plate. R&Ds for bonding have been performed. But good bonding has not been obtained. Consequently, heat transfer between Cd poison and cryogenic hydrogen was studied for the case of insufficient bonding. The heat transfers for various bonding ratios were analyzed by CFD code (STAR-CD) without any turbulence model. The temperature rise in Cd poison for insufficient bonding was estimated. As a result, even the case of the bonding ratio of only 5 %, the maximum temperature of Cd is around 75K. Therefore, the expected heat transfer between the Cd poison and the hydrogen should be sufficient for insufficient bonding. Then, it is found that the any bonding method should be available for manufacturing method of Cd poison.

Pressure rise analysis when hydrogen leak from a cracked pipe in the cryogenic hydrogen system in J-PARC

Tatsumoto, Hideki; Aso, Tomokazu; Hasegawa, Shoichi; Ushijima, Isamu*; Kato, Takashi; Otsu, Kiichi*; Ikeda, Yujiro

AIP Conference Proceedings 823, p.753 - 760, 2006/05

https://doi.org/10.1063/1.2202483

As one of the main experimental facilities in J-PARC, an intense spallation neutron source (JSNS) driven by proton beam power of 1 MW is constructed. In JSNS, cryogenic hydrogen at supercritical pressure is selected as a moderator. The total nuclear heating at the moderators is estimated to be 3.7 kW. A cryogenic hydrogen system to cool the moderators has been designed. As the most severe off-normal event for cryogenic hydrogen system, it is considered that the cryogenic hydrogen leaks when the pipe is cracked. In such a case, the hydrogen must be discharged safely as soon as possible. An analytical code that simulated the pressure change during hydrogen leak was developed. The pressure rise analysis for various sized cracks was performed, and then the required size of safety equipment was determined. It was found from the analysis that a safety valve of -42.7 mm and a rupture disk with the diameter of 37.1 mm can discharge hydrogen safely.

Estimation of heat transfer in moderators filled with cryogenic hydrogen for proton beam power of 1 MW

Tatsumoto, Hideki; Kato, Takashi; Aso, Tomokazu; Ushijima, Isamu*; Hasegawa, Shoichi; Otsu, Kiichi*

JAERI-Tech 2005-019, 16 Pages, 2005/03

JAERI-Tech-2005-019.pdf:1.29MB

As one of the main experimental facilities in J-PARC, an intense spallation neutron source (JSNS) is constructed. In JSNS, cryogenic hydrogen with temperature of 20 K and pressure of 0.5 to 1.5 MPa was selected as the moderator. The total nuclear heating at the moderators is estimated to be 3.7 kW for proton beam power of 1 MW. A cryogenic hydrogen circulation system, which plays a role in cooling spallation neutron and moderators, has been designed. For a certain operation condition, it is possible to occur boiling in the moderators. The boiling phenomenon would have an influence on the neutronic performance and the safety of the moderators. The heat transfer mechanism of cryogenic hydrogen in the moderators needs to be estimated. However, the mechanism has not been clarified until now. In this paper, the heat transfer of cryogenic hydrogen was estimated by using properties of cryogenic hydrogen and the heat transfer correlations used in other fluids, and then the operation condition of the cryogenic hydrogen system has been considered.

Development of a centrifugal hydrogen pump for the cryogenic hydrogen system in J-PARC

Aso, Tomokazu; Tatsumoto, Hideki; Otsu, Kiichi; Uehara, Toshiaki; Kawakami, Yoshihiko; Sakurayama, Hisashi; Futakawa, Masatoshi; Ushijima, Isamu*; Yoshinaga, Seiichiro*

no journal, , 

A centrifugal hydrogen pump that is a foil type self acting gas bearing had developed for the cryogenic hydrogen system in J-PARC, and the performance test was carried out in the system operation. The cryogenic hydrogen system plays a role in supplying supercritical hydrogen at a temperature of around 20 K and pressure of 1.5 MPa to three moderators and removing the nuclear heating of 3.8 kW at a proton beam of 1 MW from accelerators. In order to satisfy the neutronic performance, the temperature difference through the moderator should be reduced below 3 K. Therefore, cryogenic supercritical hydrogen should be circulated with the mass flow rate more than 160 g/s. We confirmed the characteristics of the pump satisfy the required performance.