VT-1
RG-1〜4
BR-1〜4HR-1、2PN-1、2PN-3
SH-1
DR-1
SI-1

Equipment nameInstallation place

Vertical irradiation facility
Vertical irradiation facility
Vertical irradiation facility
Hydraulic irradiation facility
Pneumatic irradiation facility
Irradiation facility for activation analysis
Vertical irradiation facility
Rotating irradiation facility
Uniform irradiation facility

Reactor core
Reactor core
Reactor core
Heavy water tank
Heavy water tank
Heavy water tank
Heavy water tank
Heavy water tank
Heavy water tank

Installation
beam port

View of the reactor room
Neutron beam experimental apparatuses in the beam hall

For PN-3

For PN-1,2

For HR-1,2

For Verticalexperiment holes

JRR-3 irradiation capsules

Experiments in the neutron activation analysis laboratory

Cold Neutron Source (CNS)
Beam experimental apparatuses

Heavy water tank

JRR-3

Utilization facilities of JRR-3

Utilization facilities of JRR-3

Neutron guide tube

Vacuum chamber

Liquid hydrogen

1G
1G-A
2G
3G
4G
5G
6G
7R
T1-1
T1-2
T1-3
T1-4-1
T2-1
T2-2
T2-3-1
T2-4
C1-1
C1-2
C1-3
C2-1
C2-2
C2-3-1C2-3-3-1
C2-3-3-2
C3-1-1C3-1-2-1
C3-1-2-2
C3-2

Cold neutron
Thermal neutron

In this facility thermal neutrons pass through -250
liquid hydrogen.
The resulting neutrons have extremely low energy
and are referred to as cold neutrons.
Cold neutrons have a wavelength longer than thermal neutrons, and it is advantageous in observing
massive molecules.

Japan Reseach
Reactor No.3

Purposes
Irradiation test, RI production
Irradiation test, RI production
Irradiation test, RI production
RI production, activation analysis
RI production, activation analysis
Activation analysis
Irradiation test, RI production
Rotating irradiation
Production of silicon semiconductor

Bird's eye view of JRR-3 reactor building

name of Instruments
HRPD
BIX-3
TAS-1
PNO
GPTAS
PONTA
TOPAN
TNRF
HQR
AKANE
HERMESPGA
RESA
FONDER
MUSASITAS- 2HER
SANS-U
BIX-4
LTAS
SUIREN
NSE
CNRF
CHOP
AGNES
NOP
MINE
SANS-JHigh Resolution Powder Diffractometer
Thermal Neutron Diffractometer for Biological Crystallography (QST*)
Triple-Axis Spectrometer
Apparatus for Precise Neutron Optics and Neutron Diffraction Topography
Triple-Axis Spectrometer (University of Tokyo)
Polarized Neutron Triple-Axis Spectrometer (University of Tokyo)
Tohoku-University Polarization Analysis Neutron Spectrometer (Tohoku University)
Thermal Neutron Radiography Facility
High Q-Resolution Triple-Axis Spectrometer (University of Tokyo)
Advanced Kinken Neutron Spectrometer (Tohoku University)
Kinken Powder Diffractometer for High Efficiency and High Resolution Measurements (Tohoku University)
Prompt Gamma-ray Analysis System
Diffractometer for Residual Stress Analysis
Four-Circle Off-Center-Type Neutron Diffractometer (University of Tokyo)
Multi-Purpose Thermal Neutron Application and Science
Triple-Axis Spectrometer
High E-Resolution Triple-Axis Spectrometer (University of Tokyo)
Small-Angle Neutron Scattering Instrument (University of Tokyo)
Cold Neutron Diffractometer for Biological Crystallography(QST*)
Low energy Triple-Axis Spectrometer
Apparatus for Surface and Interface Investigations with Reflection of Neutrons
Neutron Spin Echo Spectrometer (University of Tokyo)
Cold Neutron Radiography Facility(Test Port with Chopper)
Angle Focusing Cold Neutron Spectrometer (University of Tokyo)
Apparatus for Neutron Optics
Multilayer Interferometer for Neutrons (Kyoto University)
Small-Angle Neutron Scattering Instrument* QST: National Institutes for Quantum and Radiological Science and Technology

Outside view of JRR-3

Reactor building

Neutron beam hallReactorSpecifications of fuel elements
The reactor core is composedof 26 standard fuel elements, 6
control rods with follower fuel,beryllium reflectors, and verticalirradiation holes.
Standard fuel element
Control rod with follower fuelModerator cell

JRR-3 achieved the first criticality in 1962 as the first research reactor constructed with thehomegrown technology and had been utilized in a lot of researches from the dawn of nuclear
research and industry. In 1990,JRR-3 was modified for upgrade and resumed its operation as a highperformance and multi purpose research reactor with thermal power of 20MW.
JRR-3 has several utilization facilities for neutron beam experiments,irradiation tests for nuclear fuel and material and production of RI.Cold neutron (very low energyneutron) beams are available and utilized for clarification of life phenomena by analyzing structure ofpolymer molecules, for example.

Vertical irradiation hole
Beryllium reflector

Standard fuelelement

Follower fuelelement

Enrichmentof U-235

Approx. 20wt%

Approx. 20wt%

Fuel corematerial

Uranium-Silicon dispersion alloy(U3Si2Al)

Cladding
materialAluminum alloy

Number offuel plate

21 plates/element 17 plates/element

Specifications of JRR-3
PurposeBeam experiments,
Irradiation tests of fuels
and materials, RI production,
Activation analysis

TypeLight water moderated andcooled, pool type reactor
with low-enriched uranium

Vertical irradiation hole

Reactor core
Horizontal experimental hole
Heavy water tank

Department of Research Reactor and Tandem Accelerator,
Nuclear Science Research Institute, Japan Atomic Energy Agency
TEL (+81)-29-282-5588 FAX (+81)-29-282-5258
August.2024

Maximum
thermal power

20MW

Maximum
thermalneutron flux

Approx. 3×10 m s

Control rod
18-2-1

Reactor core (center) and heavy water tankglowed pale-blue with Cherenkov radiation

Control rod drive mechanism

JRR-3 has been utilized as a world-class high-performance research reactor for beam experiments (neutron radiography, neutron
scattering experiments, prompt gamma-ray analysis) and neutron irradiation (RI production, neutron activation analysis), etc.
Nondestructive and multi element
simultaneous analysis of sample

Medical Isotope Irradiations

Neutron activation analysis

JRR-3 produces medical RIs for use inbrachytherapy(internalradiotherapy),
which can significantly improve the qualityof life (QOL) after treatment with as little lossof function and form as possible.
Au-198 grains are used in the treatment ofcancers in the mouth or at the entrance tothe throat, and is implanted inside or next tothe area requiring treatment.

When a material is irradiated by neutrons, characteristic rays are emitted from the material. Neutron activation analysis
allows us to analyze the composition of the material
or a trace amountof impurities whichhave been takenin the material.

Nuclear reaction of goldAu(n,γ)198Au（half life：2.694 days）

197

Contributing to the elucidation of the structure of functional materials responsible
for the next generation and study of new material synthesis

Neutron diffraction
Magnetic structure iscounterclockwise

Neutron scattering experiment
Examining how neutrons are scattered by
the target material allows us to observe theordering of atoms that compose the material, the force that acts on molecules, theirNitrogen induced movements, etc.
Especially, cold neutrons with long waveCarbon
length allow us to observe the material with
Oxygen a big molecular structure more clearly, andto carry out a new field research such as
development of polymeric material andclarification of life phenomena, etc.

X-ray diffraction
NitrogenCarbonOxygenHydrogen

Magnetic structure isclockwise

Elucidation of the relationship between crystal or magnetic structure
and polarization of multiferroic magnetic materials

Image of brachytherapy
using Au-198 grains

Contributions to the function clarification of protein andthe research and development of new drugs

Electric polarization

Contribution to the medical and industrial fields

Electric polarization

Utilization of JRR-3Observation of water molecules surrounding protein by neutron diffraction

Isosurface level

Analyses of crystal structure and nuclear density
distribution of lithium-ion battery materials

Capsules(back) andirradiation samples(front)

Heavy water tankIndustrial Isotope Irradiations
JRR-3 is routinely used to develop andproduce RIs for science, agriculture andindustry.
Sealed radioactivße sources are used inindustrial radiography, gauging applications, and calibration sources for measurement instruments.

The reactor core region
FilmMUSASI(L) T2-3-1

sourceReactor coreThermal
neutronNondestructive inspectionof welded parts
Vertical experiment hole

Nondestructive inspectionof products, plants, etc.

Reactor room

Neutron radiography

Contributions to the developmentof nuclear fuels and materials

Oil movement inside the engine
Cooperation: Nissan Motor Co., Ltd.

Irradiation capsules(back) and irradiation test pieces(front)

356

Contribution to making high performanceand high reliability materials

Nondestructive and multi element
analysis for light elements etc.
Residual stress analysis
with neutrons

Irradiation to fuels
and materials
Fuels and materials forlight-water nuclear reactors, fast breeder reactors
and fusion reactors areirradiated by neutrons.
After the irradiation, theirconditions are examined ina hot laboratory, and theresults are utilized for thedevelopment and researchof future fast breeder reactors, fusion reactors, etc.

Beam hallMaterials irradiation test

Neutron imaging with high material permeability is used as one of
the nondestructive inspection methods, and it is effective for visualization of the inside of metals that are difficult to detect with X-rays.
On the other hand, since some light materials such as hydrogen
and water will absorb and scatter neutrons, the movement of waterand oil inside the product can be observed.

This is a method of measuring a changeof crystal lattice plane distance (atomicarrangement) in the material and taking it
as a change of strain, by making use of
the neutron diffraction phenomenon.
Because neutron has high material penetration property, the stress and strain in a
metallic machine part can be measured
without destruction nor contact. Thismethod has been actively utilized toinspect the material strength design, integrity and reliability of industrial products(auto parts, power generation plant material, etc.) .

Neutron induced prompt
gamma-ray analysis (PGA)

annihilation γ-ray

Fuel element
Control rod

Cold
neutronCounts

welded parts

Quantified elements :γ-ray Energy / keV

PGA is a high sensitive method ofanalysis for trace elements which areincluded in a sample, by measuring
prompt gamma-rays which are immediately emitted after neutron irradiation.
This method is effective for various element analyses from light elements, suchas hydrogen, boron and sulfur which aredifficult to analyze in neutron activation
analysis, to heavy elements. This method
has been chiefly utilized to analyze environmental samples, meteorite, industrial
materials and archaeology samples.