V.

OPERATION AND DEVELOPMENT OF
FACILITIESV. OPERATION AND DEVELOPMENT OF FACILITIES
1. Kyoto University Research Reactor (KUR)
Kyoto University Research Reactor (KUR) is alight-water moderated tank-type reactor operated at the rated
thermal power of 5MW. The core consists of plate-type fuelelements using about 20% low-enriched uranium andgraphite reflector elements. KUR is operated by using four
shim rods and a regulating rod; those are made of thestainless steel containing boron.
In FY2011, the safety review of KUR was performed toconfirm the integrity for the loss of all power supply andcooling function by reflecting the accident of TEPCO’s
Fukushima-Daiichi Nuclear Power Plant. Moreover, theadditional safety equipments were set up to achieve thehigher level of safety. The KUR operation for the joint
research of FY2012 started on June 5 and ended on
February 8. About 180 themes for the joint research werecarried out in FY2012. The integrated operation time wasabout 1156h, and the number of clinical irradiations was 68.
2. Experimental Facilities in KUR
1) Heavy Water Neutron Irradiation Facility
The Kyoto University Research Reactor (KUR)
Advanced Irradiation System has been used for Boron
Neutron Capture Therapy (BNCT) organized at Heavy
Water Neutron Irradiation Facility (HWNIF) which was
updated at 1996. The three standard irradiation modes,
namely thermal-neutrons, mixed-neutrons and epi-thermal
neutrons, have been available. The clinical irradiation
utilization under the full-power continuous KUR operation
has been realized employing both the Radiation Shielding
System consisting of the shielding door and irradiation room,and the Remote Carrying System for a patient. The safety
and the utility of this facility were improved due to the
Safety Observation System. Until the end of February 2013,
384 BNCT clinical irradiations had already been performed,
specifically, 166 for brain tumors, 150 for head & necktumors, 14 for skin tumors, 54 for body tumors such as liverand lung tumors.
2) Graphite Thermal Column2-1) CN-1: Cold Neutron Beam HoleThe monochromatic and well-collimated neutron beam
can be used. The practical intensity is 10cps at 5MW
operation. The neutron wavelength is 0.81nm with thewavelength resolution of 5%. The beam cross section is
2mm in width and 40mm in height.
2-2) CN-2: Nickel Mirror Cold Neutron Guide Tube
New monochromator (4.6 Å) is ready to use. With thismonochromator, multiple scattering from crystalline domain
in steel is disappeared. There are three monochromators(2.8 Å, 4.6 Å, 5.6 Å) Therefore, the SANS spectrometer ismainly used for the structural studies of materials with thescale of 20-200Å.

2-3) CN-3: Supermirror Cold Neutron Guide Tube
Neutrons from the supermirror guide tube are used forneutron reflectometry and development of neutron opticaldevices. The critical angle of the total reflection ofsupermirrors is twice of that of natural nickel. The
cross-section of the neutron beam is 20mm in width and90mm in height. The peak neutron wavelength is 0.18nm.
The neutron flux is 3.8 x106 n･cm-2･s-1 at 5MW operation.
2-4) VCN: Beam Hole with Very Cold Neutron Guide
A very slow neutrons from a VCN guide tube areavailable as a general purpose port.
3) Hydraulic Conveyer
Hydraulic conveyer is installed at the center of the reactor
core. This conveyer system is used for high-dose irradiationand isotope production of high specific activity. Irradiation
ample is encapsulated in a dedicated aluminum capsule, andthis is irradiated for a reactor-operating cycle (usually twodays at 1 MW and 6 hours at 5 MW) at the longest. The
thermal neutron flux of this system, which is the highest
among the irradiation systems of KUR, is 9.4 × 1013 at 5
MW operation, and 1.9 × 1013 n/cm2/s at 1 MW operation.
4) Pneumatic Tubes
Three pneumatic irradiation systems, Pn-1, Pn-2, andPn-3, are installed in, the graphite reflector region, which isright outside the core. Their thermal neutron fluxes are 1.9 ×
1013, 2.7 × 1013, and 2.4 × 1013 n/cm2/s at 5 MW operation,
and are 3.4 × 1012, 4.9 × 1012, and 4.2 × 1012 n/cm2/s at 1
MW operation, respectively. By controlled CO2 pressure,
this system rapidly conveys polyethylene capsule into thecore, and takes it back by back-pressure after the completionof the irradiation. For safety reason, irradiation time islimited to one hour at 5 MW, and to five hours at 1 MW
operation.
5) Slant Exposure Tube
Large-sized samples are to be irradiated using the slant
exposure tube, which has a thermal neutron flux of 2.6 ×
1012 n/cm2/s at 5 MW operation. This system is located at
outside the graphite reflector.
6) B-2: Thermal Neutron Beam HoleA neutron irradiation apparatus using B-2 beam hole wasinstalled in 2012. Samples on a truck are transported from aneighboring measurement room into the B-2 beam hole tobe irradiated by neutrons. Samples of large size (60 mm ×
60 mm × 300 mm) and liquid form (static or flowing liquid)
can be irradiated. Monitoring and controlling irradiation
conditions are feasible by connecting the transport truck andmonitoring/controlling devices in the measurement roomwith cables. Because irradiating position is variable, rangeof the irradiating neutron flux is wide, from 107 to 1011
nth/cm2/s. Irradiating neutron spectrum is also variable byplacing neutron shielding/moderating materials aroundsamples on the transport truck.

7) B-3: Thermal Neutron Beam HoleThe B–3 beam port had long been used as a four-circle
single-crystal neutron diffractometer (4CND), however it
was so old that its research activity on neutron science wasquite low. Therefore, we have replaced the 4CND with anew "compact" neutron diffractometer equipped with 3He
tube detectors since last fall (2012).
The neutron
wavelength, which is monochromatized with a Cu (220)monochrometer, is 0.1006 nm. The B–3 beam port is only
available as a thermal neutron irradiation device for the time
being. We will continue to keep you updated on
developments.
8) B-4: Thermal Neutron Guide Hall
Thermal neutrons are supplied through a supermirror
guide tube from the reactor to this hall. The beam crosssection at the guide exit is 10mm in width and 74 mm inheight. The characteristic wavelength is 0.12 nm andneutron flux is 5x107 n/cm2/s at 5MW operation. It is used
for neutron imaging and prompt gamma-ray analysis.
9) E-1: Exposure HoleIn this hole, facing at the side of the heavy water tank of
the heavy water thermal column, an exposure plug with anarrow helical exposure tube is inserted.
10) E-2: Exposure HoleThis hole is dedicated to thermal neutron radiography
mainly for non-destructive tests. Thermal neutrons are
extracted from the D2O tank and the thermal neutron flux is
3.2 x 105 n･cm-2･s-1 at 5MW operation, and L/D is 100. The
Cd ratio is 400. The neutron/gamma ratio is 1.1 x 106 n･
cm-2･mR-1. The neutron beam size is 16cm in diameter.
11) E-3: Beam HoleA prompt gamma-ray analysis system has been always
installed for the detection of boron-10 concentrations in the
blood for boron neutron capture therapy and the samples forthe basic researches.
12) E-4: Low Temperature LoopIn order to obtain basic information on the radiation
damage properties of various materials, a low-temperatureirradiation facility is placed in the E-4 hole. This facility cancontrol the irradiation temperatures to be between 10K and
400K under the maximum operating power of the KUR.
The maximum fast-neutron flux is 4.8×1011n/cm2/s in theirradiation chamber.
13) T-1: Through-Tube
A horizontal through-tube in the graphite thermal column(T-1) is used for the on-line isotope separator (KUR-ISOL)
of fission fragments produced by the 235U(nth, f) reaction.
Short-lived isotopes produced in the target chamber at thecenter of the through-tube are transported by the gas jet
system to an ion source located 11 m away from thechamber. The ionized activities are mass-separated and usedboth for nuclear spectroscopic studies of neutron-rich

nuclides and for condensed matter physics and chemistry.
During the shutdown of the reactor from Feb. 2006, thespecifications of KUR-ISOL, especially of the target
chamber, had been reconsidered in order to increase theefficiency of collecting fission fragments. In Feb. 2010,
the 235U target was replaced with a new one, and in FY 2012,by using KUR-ISOL, a part of a project research titled“Science and Engineering of Unstable Nuclei and Their
Uses on Condensed Matter Physics” was carried out, theresults of which are described in the present volume of
KURRI Progress Report.
14) Material Controlled Irradiation Facility (SSS)This facility has an improved control capability ofirradiation conditions, such as the irradiation temperature
and atmosphere. The irradiation temperature of a specimen
is between 340K and 773K. The maximum neutron fluxes
are 9.4×1012n/cm2/s (E>0.1MeV) and 2.2×1013n/cm2/s(E<1eV). The maximum size of a specimen is
38mm×60mm.
3. Kyoto University Critical Assembly (KUCA)
The KUCA is a multi-core type critical assembly
established in 1974 as a facility for the joint use study inreactor physics for researchers of all universities in Japan. It
has three independent cores, namely, two solid-moderated
cores (A, B cores) and one light water-moderated core (Ccore). A pulsed neutron generator is also installed, which canbe used in combination with the A-core.
In the KUCA, basic studies on reactor physics and reactor
engineering are being performed. Recent research topics
includes 1) nuclear characteristics of thorium fueled reactor,
2) nuclear transmutation studies on minor actinides, 3)
critical experiments on highly-enriched uranium cores withvarious spectrum indices, 4) subcriticality measurements
using various techniques, 5) nuclear characteristics ofcoupled core systems, 6) development of innovativetechniques for neutron measurement and their application toreactor physics experiments, 7) simulation experiments of theaccelerator driven system (ADS) using combination of
subcritical cores and the neutron generator based on FFAG
proton accelerator or DT accelerator.
For education, the reactor laboratory course on reactor
physics is offered every summer for 12 universities since1975. Approximately 160 graduate or undergraduate students
majoring in nuclear engineering are joining this course every
year. The subjects offered in the experimental course
includes 1) critical mass measurement, 2) control rod worth
calibration, 3) measurement of neutron flux, and 4) reactor
operation and fuel handling for educational purpose. The
same reactor laboratory course has been offered for Korean
undergraduate students from 2003, for Swedish graduate
students from 2006 and for Chinese undergraduate students
from 2011.

4. Electron Linear Accelerator (LINAC)
In the fiscal year 2012, the LINAC was operated for 182
days including 7 days for machine studies. The researchregion covered wide fields of nuclear data acquisition with
the neutron time-of-flight method, isotope production with
X-ray irradiation, low-temperature or low-energy electron
irradiation, and a spectroscopy with coherent THz radiation.
As a minor modification, two sets of button-type beam
position monitors has been installed on the transport line at
the back of No.2 accelerator tube to bring out the best
advantage of quadrupole magnets. A new application withthe field-emission dark current from an accelerator tube,
which is produced by high-power RF field, has opened up.
The performance records of the LINAC in FY2012 are as
follows:i) Operation (Beam-on) time: 2,024 hrs,ii) Total number of users: 855 person-days,iii) Number of collaboration researches: 25 (including 12
projects).
5. 60Co Gamma-Ray Irradiation Facility
This facility provides equipment for irradiation of pureγ−rays from the 60Co source and environment for related
experiments. It has been utilized for a wide range of
researches in physics, chemistry, biology, medical science,geological and space science, and engineering. At the
beginning of FY 2012, radiation activity of the 60Co source
was about 240 TBq and the available dose rate was about 21
kGy/h as maximum. The total operation time and the total
number of irradiations in FY 2011 were about 4147 hours
and 397 irradiations, respectively.
6. Thermal-Hydraulic Test Loop
The Thermal-Hydraulic Test Facility is open to
researchers from domestic universities and public researchorganizations. Currently, a boiling water loop and aliquid-metal two-phase flow loop are available. The boilingwater loop has a stabilized direct current power supply of 20
volts and 5000 amperes at the maximum.
7. Neutron Mirror Fabrication Facility(Ion Beam Deposition and Vacuum Evaporation for large
neutron mirrors)
Multilayer mirror is one of the most useful devices forslow neutron experiments. It consists of alternating layers of
two materials with different potential energies for theneutron. Supermirror is a stack of multilayers with gradually
increasing value of the d-spacing. A multilayer with small
d-spacing and supermirror with large-m is desirable toenlarge utilization efficiency for neutron scatteringexperiments. Here m is a maximum critical angle of themirror in unit of critical angle of natural nickel. We havesucceeded in fabricating m=6 NiC/Ti and m=5 Fe/SiGe3(Si)polarizing supermirrors by using ion beam sputtering

technique. The Ion beam deposition system is used for highquality neutron mirror fabrication. It has ion sources for
sputtering and assist. The maximum mirror size is 20 cm
diameter and the number of sputtering target is 6. The
vacuum evaporation system is used for large size mirrors.
Eight mirrors of 11 x 35 cm2 can be fabricated at once.
8. Innovation Research Laboratory
In FY 2003, the Innovation Research Laboratory (LAB)
was built next to the KUCA building. The LAB consistsof an accelerator room, experimental area, medical area andutility rooms. The commissioning of a Fixed Field
Alternating Gradient (FFAG) proton accelerator complex
was completed in the accelerator room in February, 2009.
At that time, a proton beam of 100MeV and 100pA wasobserved in the main ring of FFAG complex. This proton
beam was led to the KUCA A-core to conduct the world’s
first experiment of an accelerator-driven subcritical reactor(ADSR) on March 4, 2009, in the framework of research
project supported by the Ministry of Education, Culture,
Sports, Science and Technology (MEXT) starting from FY
2002.
In FY 2009, efforts were made to improve thetransmission efficiency of the beam transport system
between the main ring and the KUCA A-core. The beam
intensity at W target in the A-core was increased by several
tens of times compared to the previous year. On March 3,
2010, using improved proton beam, ADSR experimentswith thorium-loaded core were performed.
In FY 2010, a novel H− beam injection scheme using an
11 MeV linac as an injector was tested with a newly
constructed beam line. It uses thin charge stripping carbon
foil whose effective thickness is 10µg/cm2. No pulsed
elements such as kicker magnets or bump magnets are usedin this scheme. The H− beam is injected from the outside of
the main ring through the main magnet, and merged into thecirculating orbit at the stripping foil. The extracted beam
current from the main ring was increased up to 1nA.
In FY 2011, beam losses during acceleration have been
cured by closed orbit distortion corrections. Also extraction
kicker system up-grade has been done to increase theextraction efficiency. These improvements have realized
equivalent beam intensity of 10nA with the beam energy of
100 MeV.
The main issue in FY 2012 is the energy upgrade from
100 MeV to 150 MeV. It is able to switch the operation
mode for both energies. The beams were delivered to
KUCA for ADS experiments with the energy of 100 MeV
and to the irradiation experiments with the energy of 150
MeV. These service operations were carried out from
November to March.
9. Radioactive Waste Management Facility
The radioactive waste management facility consists ofseveral waste treatment plants, storage tanks, a waste
repository, analytical instruments for examining wastes andmeasuring radioactivity, etc.

Radioactive solid wastes are collected and assorted bytheir properties (combustible, incombustible, dried animal
carcasses and air filters etc.), then packaged in the drums
predetermined for their properties. These drums are stored
in the repository under surveillance with other wastes suchas high-level liquid wastes, concentrate by evaporation,
dehydrated sludge by chemical coagulation etc. described
below. Parts of these wastes in the repository are delivered
about once a year to the waste dealer granted legal license
on radioactive waste management.
A new repository for radioactive waste storage wasconstructed in FY2002. The new repository with an area of
about 300 m2 has an overhead traveling crane with amaximum load of 3 tons and a control room. In addition, it
should be mentioned that outdoor tanks for radioactive
liquid waste storage are covered with steel-framed slate roof
in FY2002.
High-level liquid wastes (higher than 3.7x104 Bq/cm3) aretemporarily stored for cooling at the areas of their generation
till they can be handled, then stored in the repository without
any condensing process. Other radioactive liquid wastes(medium-level and low-level) are treated adequately to theirradioactivity and physicochemical properties as follows1)-3).
The treated liquids are stored in monitoring tanks, thenreleased into the environment after confirmation that theconcentrations of radionuclides in the liquid are below thelegal permissible limits.
1) Evaporation
Medium-level liquid wastes (0.37-3.7x104 Bq/cm3) and/or
liquid wastes with high salt content are treated by thesteam-heated reboiler-type evaporator that separates
evaporated steam from remaining concentrate, whichcontains most of radioactivity in the waste. Entraining
droplets are removed from steam stream by three particle
separators; cyclone, packed column and perforated platecolumn.
The evaporated steam is condensed bycondensers and stored in monitoring tanks. The concentrateby evaporation is accommodated in containers. The
treating capacity of this evaporation system is 0.5 m3/h.
2) Chemical Coagulationand Freezing-and-Thawing
Low-level radioactive liquid wastes (below 0.37 Bq/cm3)
are treated by two series of chemical coagulation system,
which consist of chemical tanks, rapid mixing tanks,
flocculator-sedimentators, anthracite filters etc. In thistreatment process, radioactive materials are removed fromliquid waste into sediment slurry by chemical coagulation
followed by precipitation. This coagulator has the treating
capacity of 5 m3/h for one series. Sediment slurry is
dehydrated by two series of freezing-thawing process, eachof whose treating capacity is 0.2 m3/d. Dehydrated slurry isaccommodated in containers. The decontaminated effluent
from the coagulator is filtered by anthracite columns andstored in monitoring tanks, then discharged into theenvironment.

3) Ion Exchange
Two series of ion exchange system are used for low
salt-content liquid waste, or also utilized for further
treatment of the liquid wastes already treated by theevaporator or the coagulator, if necessary. Each ion
exchange system consists of a cation exchange column, ananion exchange column, a mixed column and an
inorganic-resin column. The inorganic-resin column isparticularly capable of cesium removal. Liquid waste istreated by the proper combination of columns considering
nuclides in the liquid waste. One ion exchange system has
the treating capacity of 5 m3/h. Liquid waste is purified byadsorbing ionic radionuclides onto functional groups of ion
exchange resin, and the purified liquid is introduced tomonitoring tanks.