Thermal-hydraulic design calculations for JRR-3 cold neutron source with the new moderator cell

Tokunaga, Sho; Horiguchi, Hironori; Nakamura, Takemi

JAEA-Technology 2023-001, 37 Pages, 2023/05

JAEA-Technology-2023-001.pdf:1.39MB

The cold neutron source (CNS) of the research reactor JRR-3 converts thermal neutrons generated in the reactor into low-energy cold neutrons by moderating them with liquid hydrogen stored in the moderator cell. Cold neutrons generated by the CNS are transported to experimental instruments using neutron conduits, and are used for many studies of physical properties, mainly in life science, polymer science, environmental science, etc. Improvement of cold neutron intensity is essential to maintain competitiveness with the world's research reactors in neutron science, and we are developing a new CNS that incorporates new knowledge. The current moderator cell for the CNS of JRR-3 is a stainless-steel container which is a canteen bottle type, and the cold neutron intensity can be improved by changing the material and shape. Therefore, the basic specifications of the new moderator cell were changed to aluminum alloy which has a smaller neutron absorption cross section, and the shape was optimized using a Monte Carlo code MCNP. Since these changes in specifications will result in changes in heat generation and heat transfer conditions, the CNS of JRR-3 was re-evaluated in terms of self-regulating characteristic, heat transport limits, heat resistance and pressure resistance, etc., to confirm its feasibility in thermal-hydraulic design. This report summarizes the results of the thermal-hydraulic design evaluation of the new moderator cell.

Fundamental aspects of neutron moderators and neutron beam optics for designing high intensity laser-driven neutron source

Ikeda, Yujiro; Shimizu, Hirohiko*

Reza Kenkyu, 46(11), p.641 - 646, 2018/11

https://doi.org/10.2184/lsj.46.11_641

In viewing significant progresses in technical achievement toward a high-intensity neutron source driven by a high-power laser came up with the high power laser development, we have reviewed the currently most advanced moderator system and neutron optics, which are the key elements for the neutron beam applications. Regarding the moderators, concepts adopted in J-PARC pulsed neutron source, which is one of most advanced system, were described to give a baseline design. Also a new direction of moderator concept is shown, which could be a high brightness candidate for the high-intensity laser driven system. On the neutron optics, the most fundamental consideration is primarily reviewed along with recent progress in new devises for enrichment of neutron-beam characteristics.

Coupled hydrogen moderator optimization with ortho/para hydrogen ratio

Kai, Tetsuya; Harada, Masahide; Teshigawara, Makoto; Watanabe, Noboru; Ikeda, Yujiro

Nuclear Instruments and Methods in Physics Research A, 523(3), p.398 - 414, 2004/05

https://doi.org/10.1016/j.nima.2003.11.427

Neutronic performance of a coupled hydrogen moderator was studied as a function of para hydrogen concentration, moderator thickness, height and premoderator thickness. It was found that a thick (120140mm) moderator with 100% para hydrogen was optimal to provide the highest time- and energy- integrated neutron intensity below 15 meV together with the highetst possible pulse-peak intensity. Low-energy neutron distribution on the moderator viewed surface was found to exhibit an intensity-enhanced region at a picture frame part near premoderator. The rather peculiar distribution suggested that the moderator and the viewed surface must be designed so as to take the brighter region near premoderator in use.

J-PARC construction and its linac commissioning

Yamazaki, Yoshishige

Proceedings of 9th European Particle Accelerator Conference (EPAC 2004), p.1351 - 1353, 2004/00

The J-PARC (Japan Proton Accelerator Research Complex) is under construction in JAERI Tokai site. The beam commissioning will start there by the end of 2006. Prior to this, the front end of the linac was beam-commissioned in 2003 at KEK. The negative hydrogen beam with a peak current of 30 mA was accelerated up to 20 MeV by the first tank of the three DTL's following the 3-MeV RFQ linac. The 324-MHz DTL contains the electro quadrupole magnets with water-cooling channels specially fabricated by means of electroforming and wire-cutting technologies. The construction status of the J-PARC accelerator is also presented.

The JAERI-KEK joint project for the high-intensity proton accelerator, J-PARC

Yamazaki, Yoshishige

Proceedings of 2003 Particle Accelerator Conference (PAC 2003) (CD-ROM), p.576 - 580, 2003/00

The JAERI-KEK Joint Project for the High Intensity Proton Accelerator, now referred to as the J-PARC Project (Japan Proton Accelerator Research Complex), comprises a 400-MeV linac, a 3-GeV, 25-Hz Rapid-Cycling Synchrotron (RCS), and a 50-GeV Main Synchrotron (MR). In contrast to the SNS or the ESS, the J-PARC makes use of the RCS in order to produce MW-class pulsed spallation neutrons rather than a combination of the full-energy linac and the compressor ring.

Development of high intensity pulsed neutron source and its application

Oyama, Yukio

Radioisotopes, 51(5), p.219 - 227, 2002/05

https://doi.org/10.3769/radioisotopes.51.219

no abstracts in English

Performance test of micro-fission chambers for in-vessel neutron monitoring of ITER

Yamauchi, Michinori*; Nishitani, Takeo; Ochiai, Kentaro; Morimoto, Yuichi*; Hori, Junichi; Ebisawa, Katsuyuki*; Kasai, Satoshi

JAERI-Tech 2002-032, 41 Pages, 2002/03

JAERI-Tech-2002-032.pdf:2.62MB

A micro-fission chamber and a dummy chamber without uranium were fabricated and the performance was tested. They are designed to be installed inside the vacuum vessel of compact ITER (ITER-FEAT) for neutron monitoring. Vacuum leak rate of the chamber, resistances between central conductor and outer sheath, and mechanical strength up to 50G acceleration were confirmed to meet design criteria. Gamma-ray sensitivity was measured with Co gamma-ray irradiation facility at JAERI Takasaki. The output signals for gamma-rays in Campbelling mode were estimated to be less than 0.1% those by neutrons at the location behind the blanket module in ITER-FEAT. Detector response for 14 MeV neutrons was investigated with the FNS facility. Excellent linearity between count rates and neutron fluxes was confirmed. According to the test for the change of surrounding materials, the sensitivity was enhanced by slow-downed neutrons, which agreed with the calculation result by MCNP-4C code. As a result, it was concluded that the developed micro-fission chamber is applicable for ITER-FEAT.

Premoderator optimization of decoupled hydrogen moderator

Harada, Masahide; Teshigawara, Makoto; Kai, Tetsuya; Sakata, Hideaki*; Watanabe, Noboru; Ikeda, Yujiro

JAERI-Research 2001-016, 32 Pages, 2001/03

JAERI-Research-2001-016.pdf:1.74MB

An optimization study on the premoderator, the reflector material choice and a length of the liner is carried out for the design of high performance decoupled hydrogen moderator. NMTC/JAM and MCNP-4C are used for the neutronics calculation. The result indicates that, assuming premoderator dimensions and decoupling energy is controlled, the decoupled hydrogen moderator with a premoderator can provide better pulse characteristics than that without the premoderator for a Be reflector. On the selection of the reflector material, it is clearly shown that Pb and Hg reflectors give merits in using the premoderator for higher intensity and reduction of energy deposition in moderator. It is also shown that a H2O premoderator provides a short tail while a D2O premoderator provides the high peak intensity. Minimum liner length is evaluated to be 20 cm from the viewpoint of neutronics.

Status of high intensity proton accelerator project and its research program

Oyama, Yukio

Nihon Genshiryoku Gakkai Monte Karuro Ho Ni Yoru Ryushi Shimyureshon No Genjo To Kadai, p.183 - 191, 2001/01

no abstracts in English

Neutronics study on the JAERI 5MW spallation neutron source; Neutronic performance of the reference target-moderator-reflector system and the target shape/size effects

Teshigawara, Makoto*; Watanabe, Noboru*; Takada, Hiroshi; Kai, Tetsuya; Nakashima, Hiroshi; ; Oyama, Yukio; Ikeda, Yujiro; Kosako, Kazuaki*

JAERI-Research 99-020, 33 Pages, 1999/03

JAERI-Research-99-020.pdf:1.83MB

no abstracts in English