IAEA-SM-360/47 CURRENT STATUS OF RESEARCH REACTOR AT THE TOKAI RESEARCH ESTABLISHMENT T. YAMADA, S. KOBAYASHI, F. SAKURAI, K. KAIEDA Department of Research Reactor, Tokai Research Establishment, Japan Atomic Energy Research Institute, Tokai-mura, Nakagun, Ibaraki-ken, Japan Abstract Since 1957, several research reactors have been sequentially constructed in Japan Atomic Energy Institute(JAERI), and they have been extensively utilized for various studies. At present, two reactors, the upgraded Japan Research Reactor No.3 (JRR-3M), the Japan Research Reactor No.4 (JRR-4) are in operation. This paper describes the present circumstance concerning those utilization and utilization facilities, including a development of new facility and instruments. 1. INTRODUCTION The JRR-3M is reactor upgrading from old Japan Research Reactor JRR-3. The modification works of JRR-3 were started in 1986 for get higher performance of reactor utilization, and started full power operation again for utilization in 1990. JRR-3M is a light water moderated and cooled swimming pool type reactor with beryllium and heavy water reflector with the maximum thermal power of 20 MW. Its operation cycle is basically consist of four weeks of full power operation and one week of shut down for refueling, irradiation capsule handling and maintenance works. Normally, the annual operation consists of seven or eight operational cycles mentioned above. The integrated thermal power of 26,520 MWday was attained at the end of fiscal year 1998. Fuel conversion 3 program from U-Alx dispersed MTR type fuels with a U-density 2.2 g/cm to U3Si2-Al dispersed MTR type fuel with a U-density of 4.8 g/cm3 and a burnable poison of Cd wire is progressing. By this conversion, the number of spent fuels can be reduced, and it will supply stable neutron beam to many users. The JRR-3M is the first neutron source which is equipped with a large scaled cold neutron source(CNS) and neutron guide tubes with a total length of more than two hundred meters in Japan. This remarkable feature makes it possible to open up new research field such as soft material science, and also makes it possible to install many instruments along the guide tubes. The modification works of JRR-4 were started in October 1996 for core conversion to LEU, utilization facilities upgrading and renewal of some reactor program, the new fuel is manufactured as 20% lower enriched uranium silicide fuel without changing of structure and any size. At the same time, a medical irradiation facility for Boron Neutron Capture Therapy (BNCT) was additionally installed, and were modified a Neutron Activation Analysis (NAA) system for short life nuclides and a large scale pipe irradiation system. Furthermore many works were conducted such as the renewals of instrument and control system, repairing of reactor building etc. JRR-4 is a light water moderated and cooled swimming pool type reactor with graphite reflector with the maximum thermal power of 3.5MW. Its operated six hours a day, four days a week and about 43 weeks a year. The full power operation of JRR-4 was resumed with LEU fuel in October 1998, and started the joint use of it from the beginning of 1999. The characteristics of these reactors are shown in Table I. And the operation schedules of the two reactors in FY 1999 are shown in Fig. 1. 1 IAEA-SM-360/47 1999Apr. May. Jun. Jul. Aug. Sep. Oct. Nov. Dec.2000Jan. Feb. Mar. Apr. J 530 10 4 14 9 19 13 23 3 2217 3125 6 31 R 10 weeks 4 weeks R 1 2 3 4 5 6 7 8 * - Characteristic measurement 3 Governmental inspection of silicide fuel core * Overhaul and inspection M Vacation 1999Apr. May. Jun. Jul. Aug. Sep. Oct. Nov. Dec.2000Jan. Feb. Mar. Apr. 4234 31 4 2 J 7 weeks 17 weeks 13 weeks R 6 weeks 8 weeks R * * - Nuclear Engineering School training * Overhaul and inspection 4 Governmental inspection Vacation FIG.1. Operation schedules of reactors JRR-3M and JRR-4 (FY 1999). 2. UTILIZATION FACILITIES JRR-3M and JRR-4 have both of irradiation facilities and neutron beam experimental facilities. Fig.2 shows the arrangements of the experimental holes and tubes of JRR-3M, and reactor core configulation of JRR-4 are shown in Fig.3. And characteristics of these facilities are showns Table II and III. As for the JRR-3M, nine irradiation holes are located in the core region for the capsule irradiation. They are used for material irradsiation tests and radio isotope(RI) production. In the heavy water reflector region, nine vertical holes are arranged. One of the holes is used for the CNS facility and the others are used for the irradiation experiments such as an activation analysis, a semiconductor production by silicon doping, RI production and so on. The CNS facility is a vertical thermo-syphone type using liquid hydrogen at 20K as a moderator. A schematic diagram of the CNS facility is shown in Fig.4. The CNS gain at wavelength of 5 Angstrom is 10. This facility is operated all during the reactor operation. Horizontal beam tubes are arranged in the heavy water tank for neutron beam experiments, nine horizontal beam tubes(1G through 6G, 7R,8T and 9C) are arranged tangentially to the core, in order to reduce fast neutrons and gamma rays in the neutron beam. The layout of neutron beam experimental instruments are shown in Fig.5. Seven out of the nine tubes, 1G through 6G and 7R, supply thermal neutron beam for experiments in the reactor room. The 8T beam tube transmits thermal neutrons into the beam hall through two thermal neutron guide tubes. The 9C beam tube transmits cold neutron from CNS into the beam hall through three cold neutron guide tubes. It has 2 IAEA-SM-360/47 become possible to install a lot of beam experimental instruments along these neutron guide tubes. Five neutron guide tubes, T1 and T2 for thermal neutrons and C1,C2 and C3 for cold neutrons, are installed to extract neutron beams efficiently from the heavy water reflector and the liquid hydrogen moderator in the heavy water tank through the horizontal beam tube 8T and 9C respectively to the beam hall. Of the seventeen neutron beam ports, an eight are set on the thermal neutron guide tubes and another nine on the cold neutron guide tubes, are available in the beam hall, 30m wide x 50m long, which is located next to the reactor building. The characteristic wavelength of T1 and T2 are 2 Angstrom and their radius of curvature is 3,340m. The length is about 60m. C1 and C2 with a radius of curvature of 834m have a characteristic wavelength of 4 Angstrom. Their total length is about 31m and 51m respectively. C3 with a radius of curvature of 370 m has a characteristic wavelength of 6 Angstrom, and is 31 m long. Their categories by instrumental type are listed in Table IV. The total number of instruments installed in a reactor hall and a guide hall are 26, and some instruments are being developed. As for the JRR-4, five irradiation holes located in the reflector region for the capsule irradiation. They are used for the irradiation experiments such as an activation analysis, a semiconductor production by silicon doping, RI production and so on. And also a medical irradiation facility for BNCT is installed. Figure 6 shows the cross sectional view of neutron beam facility for BNCT at JRR-4. The medical irradiation facility has been composed of a heavy water tank, a collimetor and an irradiation room. The heavy water tank has four layers of heavy water for spectrum tailoring and 75cm thickness aluminum for the shield of fast neutron. The collimator is for collimating thermal neutron by graphite also epithermal neutron by lead, as well as shielding gamma ray by bismuth. Furthermore, a prompt gamma ray analyzing(PGA) system is constructed in the reactor pool. 9C 8T 1G 2G N S 3G Pool side T Pn D 4G Fuel elements DD: Pipe 5G TT: Pipe 6G 7R Reflector elements NN: Pipe Control rods Vertical Irradiation Holes: Pn: Pneumatic tube HR,PN,PN3,SI,DR,RG,VT-1,BR,SH Neutron source SS: Pipe Horizontal Beam Tubes: Irradiation tubes 1G 6G,7R,8T,9C FIG.2. Arrangement of experrimental holes FIG.3. Reactor core configuration of JRR-3M. of JRR-4. 3 IAEA-SM-360/47 Reactor Pool He Refrigerator Condenser Low Temperature H2 Buffer Tank Channel Tube Subpool Heavy Water Tank Guide Tunnel Neutron Guide Tube Core Vacuum Chamber FIG.4. Schematic diagram of CNS facility in JRR-3M. 4 IAEA-SM-360/47 Reactor Building Experimental Building TAS-1 MINE SANS-J 2G BIX- E C3-1-2 PNO AGNES C3-2 CNRF C2-3-1 3G C3-1-1 PGA C2-3-2 1G-A LCE C2-3-2A HRPD C2-3-3 1G C2-3-4 GPTAS C3 NSE C2-2 4G 3G 2G LTAS NSM 4G 1G C2 C2-1 5G 9C C1 HER ULS RESA 6G T2 SANS-U 8T C1-1 C1-3 T2-1 C1-2 PONTA 7R 5G T1 T2-2 > BIX- @ TAS-2 T2-3 T2-4 TOPAN TNRF 6G 7R Guide Hall PGA T1-4-1 LCE T1-4-1A HQR KSD KPD [NDC] T1-4-2 Reactor Hall T1-1 T1-2 T1-3 T1-4-3 0 10m FIG.5. Layout of neutron beam experimental instrument at JRR-3M. 5 IAEA-SM-360/47 No.1 Pool Core Tank P.E.+Boron Lead Irradiation Room Core Bismuth D2O Tank Cd Shutter FIG.6.