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JAERI-KEK Joint Project Newsletter No. 4 April, 2001
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High Intensity Proton Accelerator Project proposed jointly
by the Japan Atomic Energy Research Institute (JAERI)
and the High Energy Accelerator Research Organization (KEK)
http://jkj.tokai.jaeri.go.jp/
Editorial Board:
Masatoshi ARAI (chair): masatoshi.arai@kek.jp
Tomokazu FUKUDA: tomokazu.fukuda@kek.jp
Yujiro IKEDA: ikeda@cens.tokai.jaeri.go.jp
Hideaki YOKOMIZO: yokomizo@linac.tokai.jaeri.go.jp
Shinya SAWADA: shinya.sawada@kek.jp
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CONTENTS
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0. Editorial Note
1. Recent Progress of the Joint Project between JAERI and KEK on High-
Intensity Proton Accelerators (Shoji NAGAMIYA)
2. Report from Nuclear and Particle Physics Facility (Jun IMAZATO)
3. Recent Activity of Neutron Science Group (Yukio OYAMA)
4. Report from the Muon Science Group (Yasuhiro MIYAKE)
5. Report from the Accelerator Driven Transmutation (ADS)
Experimental Facility Group (Hiroyuki OIGAWA)
6. Activities of the 3-GeV Proton Beam Transport Line Group (3NBT)
(Shinichi SAKAMOTO)
7. Radiation Safety Group Report (Norio SASAMOTO)
8. Activities of Facility Construction Group (Yo-ichi AKUTSU)
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0. Editorial Note
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1. Recent Progress of the Joint Project between JAERI and KEK on High-
Intensity Proton Accelerators
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by Shoji NAGAMIYA
My report in this volume is brief. We are now working to form a
new organization for the construction phase. The major issue in this
task has been to clarify the responsibility split among three bodies:
JAERI, KEK, and the Project Team. Also, an issue has been on how to
locate each box in the organizational chart in order to ensure strong
and efficient construction work. These tasks are almost complete and
the new organization is expected to start soon.
After the approval of our construction budget, the users groups
started lively discussions towards instrumentation of the facility.
These users groups are: a) nuclear/particle group, b) neutrino group,
c) neutron group, d) muon group, and e) accelerator-driven transmutation
group. Within a short time scale I plan to form
1) International Advisory Committee and
2) Committee with an active participation by users groups
for the Project. The first discussion item in these committees will be
the strategy of facility construction under a severe competition among
users for limited resources.
During the past three months the most significant event was a
strong movement from the Local Government. Ibaraki Prefecture (which
includes both Tsukuba and Tokai) formed a Forum with which to discuss
methods on how to create active scientific towns in the North Area of
Ibaraki (Note that Tokai is in the North Area whereas Tsukuba is in the
South Area). In particular, the Governor is enthusiastic about our
Joint Project.
The new fiscal year of Japan started on April 1. Our Project
Team has many new staff members. We started a new phase of the project
--- the construction phase. With a refreshed feeling and mind, we are
working hard everyday.
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2. Report from Nuclear and Particle Physics Facility
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by Jun IMAZATO
Although the construction of the 50 GeV experimental facility will
start only in 2004, the conceptual design of a hall, beam tunnels and
utility buildings is already in progress at the KEK construction
department and the working group of IPNS(Institute of Particle and
Nuclear Studies). After the completion of the first construction phase
the hall will accommodate one primary proton line, one production target
station and a few secondary lines (including lines to be moved from the
present KEK 12 GeV facility). The primary line in the hall will be
shielded by cast-and-fixed concrete walls so as to achieve high shielding
performance with a relatively low cost. Therefore, the layout of
secondary line tunnels from the target has to be carefully optimized.
Since the choice and detailed design of the secondary lines are still
to be worked out taking into account experimental proposals or letters
of intent, the guiding design principle at the moment is to keep the
capability to install any typical secondary channels.
The fast extraction beam line to the neutrino beam facility,
which will be constructed in the second phase, is now also being
designed. Because of a small extraction radius it should be
superconducting. A working group involving the KEK cryogenics division
is now starting studies of superconducting magnets and a cooling system.
As for the development of beam instruments under the high intensity
condition, the most difficult part for both slow and fast extraction
beams is the production target. Another working group in IPNS is also
investigating possible target design and a cooling scheme.
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3. Recent Activity of Neutron Science Group
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by Yukio OYAMA
A detailed design for moderators is in progress, especially for
decoupler materials and an estimation of the ortho/para effect on a
liquid hydrogen moderator. A mock-up test facility for a remote
maintenance system has been built for target development. The system
has a power manipulator, a master-slave manipulator and a target trolley
mock-up. As for safety issues, several analyses are being carried for a
Target-Moderator-Reflector (TMR) system. In addition, a preliminary
spectrometer arrangement has been designed, as well as the building
layout and supporting facility.
The spectrometer and neutron device sub-groups met
on March 26 and discussed the next step of activities at the beginning
of the project. A second seminar on Neutron Application to Industry was
held at KEK on March 1 with more than 60 people focusing on examples at
KENS (Pulsed Neutron Facility in KEK). The Symposium on Spallation
Materials was also held at KEK on March 21-22 to discuss the status of
materials development for a spallation source and accelerator driven
system.
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4. Report from the Muon Science Group
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by Yasuhiro MIYAKE
The pion target subgroup is now working on R&D of a relatively
simple stationary target rather than a rotating target, which has been
used at PSI for more than ten years. For the phase 1, we are planning
to install one pion target with a thickness of < 20 mm upstream of the
neutron target. By the interaction of the high intensity (3 GeV, 333
micro A) proton beam with a 20 mm carbon target, 4.5 kW of heat is
deposited into a beam spot of 20 mm in diameter. By a calculation of
the program ANSYS code, the central target temperature was estimated
to be less than 1500 degrees C, at which temperature the vaporizing
pressure is the order of 10(-9) mbar. This indicates that a viable
design of a simple stationary target should be possible and this was
therefore adopted into the preliminary design, if it is reliable and
long lasting.
The target and its local shield up to a level of 2.5 metres
above beam level are contained in a vacuum vessel. Below this 2.5
metre level, all services will be hard wired or plumbed and any
mechanical connections rigorously minimized. At the service connection
level it is expected that non-radiation-hard components such as rubber
"O" rings, motors, and conventional cabling, etc. may be utilized.
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5. Report from the Accelerator Driven Transmutation (ADS)
Experimental Facility Group
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by Hiroyuki OIGAWA
As part of the research and development for the Accelerator
Material Irradiation Facility, a liquid Pb-Bi loop for material testing
was installed in JAERI/Tokai at the end of January. The loop was
successfully operated at 450 degree centigrade with 50 degree centigrade
of temperature difference for more than 1200 hours.
For the safety analysis for the ADS physics experimental facility,
the influence of a hypothetical accident was preliminary evaluated. It
was shown that the dose rate around the facility can be controlled at a
low level by emergency shutdown mechanism.
The group for the experimental facility design was merged with the
research group for the transmutation system in April. This new group,
named as "Nuclear Transmutation Group", will undertake broad research
and development for the partitioning and transmutation technology to
reduce the environmental burden of long-lived high level waste, as well
as the development of the ADS Experimental Facility.
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6. Activities of the 3-GeV Proton Beam Transport Line Group (3NBT)
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by Shinichi SAKAMOTO
Beam transport of the 1-MW proton beam is one of the key issues in
this project. The proton beam from the 3-GeV synchrotron is transported
into the Neutron-Muon Experimental Facility for materials and life
science. Because of geographical constraints in the site, the beam
transport line is 320 m long with a 4.8-m change in elevation and a
30-degree horizontal bend. It is not obvious how to keep beam losses
less than 0.01 % in such a long and rather complicated beam line. The
distribution of beam halo when the beam is extracted from 3-GeV
synchrotron is not yet known. The beam line magnets are, therefore,
designed to have an aperture just big enough to accept the beam of
maximal possible emittance without halo scrapers. The beam monitor and
control systems will play an important role to minimize beam loss.
In the Neutron-Muon Experimental Facility, a muon production
target is placed in the proton beam upstream of the neutron source.
The beam loss around the muon production target is as high as 70 kW.
High dose is expected in the air around the proton beam line. The high
radiation also forms NOx and O3 in the air, which is eventually
turned into nitric acid (HNO3). That may corrode equipment in the
beam line. We visited PSI in Switzerland and ISIS (RAL) in the U.K. and
studied similar beam lines of their high-intensity proton accelerator
facilities. Airflow in the beam line and surface treatment of iron and
concrete can prevent any corrosion due to nitric acid. Now we are
building the conceptual design of the beam line and will start detailed
design of the whole beam transport line system soon.
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7. Radiation Safety Group Report
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by Norio SASAMOTO
In order to rationalize a facility construction design, the beam
loss assumption of the accelerators was re-evaluated to change the
assumption of 1 W/m to 0.1 W/m at any region except for specific ones,
where a large amount of localized beam loss remains unchanged. Then,
some shielding design studies were carried out on the basis of the newly
evaluated assumptions, for calculations of bulk shielding, activation of
air and cooling water, streaming and skyshine.
Above all, neutron streaming is a key issue for design
rationalization. Thus, we improved the streaming calculation code DUCT-III
by coupling the penetration calculation code PKN-H, having shown that its
accuracy is good enough to be applicable to the actual design calculation.
A shielding experiment was successfully completed at AGS-BNL by using
proton beams of 2.83 GeV and 24 GeV. Measurements were made for neutron
source distributions around the mercury target and neutron reaction
rate distributions in shielding materials of 4 m thick ordinary concrete
and 3 m thick iron. Spallation products were also measured in
mercury and structural materials irradiated by proton beams and
secondary neutrons.
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8. Activities of Facility Construction Group since last December
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by Yo-ichi AKUTSU
Pre-design of the main facilities and utilities has been completed
based on the latest required specifications. Especially construction of
a temporary bridge over the Shinkawa River and a temporary road to be
used as a haul road for the dug dirt were studied. Concerning
replanting in the forest after the completion of the construction, the
basic policy and method of planting have been considered under the
guidance of the authorities. However, it is necessary to implement
some cost-reduction in the 1st stage construction of the linac building
during the next fiscal year as the current design goes over the facility
construction budget.
For the FY 2001 final design, JAERI and KEK will need to decide
the details of sharing construction costs, to standardize the design and
the cost, to proceed with the application to the government, and so on.
In order to start the construction of the linac building in 2001,
the final design of the central boiler building, cite survey and soil
evaluation are underway, and the budget request for the coming FY 2002
is under preparation.
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