Accelerator-based epithermal neutron source for BNCT using thin-layer solid-Lithium target Yoshio Imahori a*, Ryo Fujii a, Masaru Nakamura a, and Jun Itami b a†Cancer Intelligence Care Systems, Inc., Ariake 3-5-7, Koutou-ku, Tokyo, 135-0063 Japan b National Cancer Center, Tsukiji 5-1-1, Chuo-ku, Tokyo, 104-0045 Japan Cancer Intelligence Care Systems, Inc, 2014

Cancer Intelligence Care Systems, Inc., 2014 NCC- CICS - AccSys "Optimization of matching in the major components of the accelerator neutron source for BNCT“ in Dec-2012 National Cancer Center Japan NCC – CICS "Establishment of the standard of boron neutron capture therapy (BNCT) using an accelerator" in Dec 2010 CICS-AccSys “Towards utilization of hospital based-type BNCT" in Sep 2012 CICS, Inc. AccSys Technology HITACHI 1 Moriya Cutlery Laboratory, Ltd. 2 Shimane Institute for Industrial Technology, 3 Tanaka Kikinzoku Kogyo K.K. 4 Nippon light Metal Co., Ltd. 5 Fujidenolo Co. Ltd. 6 AdIn Research,Inc. 7 Showa Shinku Co., Ltd. 8 TOYAMA, Inc. Medical-engineering collaboration research in many fields Cancer Intelligence Care Systems, Inc., 2014

Location of National Cancer Center in Tokyo National Cancer Center Japan Cancer Intelligence Care Systems, Inc., 2014

NCC: New Facility for Accelerator based BNCT New building for BNCT Radiation shield in BNCT room B-1 Cancer Intelligence Care Systems, Inc, 2014

Cancer Intelligence Care Systems, Inc, 2014 (Radiation Shield) 6.5 m 1000kg (RFQ Linac) 1.7m 6.0 m 10t (Radiation Shield) 5t (Beam Shaping Assembly) 8.8 m Cancer Intelligence Care Systems, Inc, 2014

High Current Proton RFQ Linac Injector RFQ Linac Q-Mag. Bending Mag. Specification ・Particle Proton Steering Mag. ・Beam Energy 2.5 MeV ・Beam Current 20 mA (CW) ・Ion Source Microwave Ion Source ・LEBT Solenoid ・Accelerator RFQ BPM ・RF Klystron (330kW CW, 400MHz) Cancer Intelligence Care Systems, Inc, 2014

Whole picture of high current Linac for BNCT

Proton accelerator with RFQ type

The record of 2.46MeV and 10mA is attained. Cancer Intelligence Care Systems, Inc., 2014

Cancer Intelligence Care Systems, Inc., 2014 A design and the strategy for the solid 7Li-target device Metal lithium is suitable for 7Li(p,n) 7Be reaction in low Ep. Ep=2.5MeV makes it possible 7Li thin-layer within 100μm in a case of vertical bombardment. The thin-layer permits high heat conduction. Heat conductivity is inverse proportion to the distance of heat movement. Thus 50μm thickness of Li becomes 40 times more heat conductive than that of 5 mm of Be. 7Li contaminated with 7Be can be easily removed by chemical reaction and can be transported to a distant area from patient and medical staff. Low energy neutrons max En=0.6MeV can be obtained by 2.5MeV Ep and Li-target, resulting that slowdown of 1 to 60th permits to reduce neutron energy to <10keV. Cancer Intelligence Care Systems, Inc., 2014

Cancer Intelligence Care Systems, Inc, 2014 7Be contamination and Li-target cleansing - Radioactivity with side nuclear reactions - Cancer Intelligence Care Systems, Inc, 2014

Handling of 7Be in compliance with the regulations 7Li(p,n)7Be Proton Beam 半減期：53.29day T1/2 Accumulation Drainage Processing 洗浄 Wash out 貯留槽へ移送 Transfer to reservoir tank 貯留槽 （21ヶ月間貯留） Accumulation for 24 month 減衰保管 （21ヶ月間） Storage for decay for 24 month Transfer to main tank Drainage after dilution Cancer Intelligence Care Systems, Inc, 2014

Cancer Intelligence Care Systems, Inc, 2014 In situ neclear reaction in Li-6 metal (7.5%) Production of 3H Neutron Energy Cross Section Thermal flux Saturation Yield (eV) (cm2) （ n/cm2/s ） 3H (n/s = Bq) 0.025-0.01 940 1.555E+09 4.085E+07 0.01-0.005 1480 2.900E+08 1.200E+07 0.005-0.001 2122 9.217E+07 5.466E+06 0.001-0.0005 4740 2.813E+06 3.726E+05 0.0005- 6700 7.149E+05 1.339E+05 Total 3H 1.941E+09 5.882E+07 3H half life 108010.8 hour Accumulation per 1 hr 3.774E+02 Bq per 8 hr 1.875E+03 7.547E+03 （8hr×25days） 1.614E+07 3.096E+07 2.940E+07 1.59 mCi per 25 day per 1 year Per 2year Continuous for 12.3yeras Using 99.99% of Li-7 metal makes 3-order down. < 1.6μCi Cancer Intelligence Care Systems, Inc, 2014

Equipments for Li-deposit test Cancer Intelligence Care Systems, Inc, 2014

Lithium deposit test on the sham glass target Correlation of Li deposit profile between estimation and measurement Estimation Measurement Time-dependent and formula-dependent deposit of thin-layer Li ⇒　 possible to make the surface flat Cancer Intelligence Care Systems, Inc, 2014

Does lithium-target explode sure enough? No worries !!! Thin-layer solid Li-target Total amount of Lithium <0.5g Cancer Intelligence Care Systems, Inc, 2014 Cancer Intelligence Care Systems, Inc, 2014 16

Cancer Intelligence Care Systems, Inc, 2014 Fourier's Law and boiling curves q = α⊿T Log q CHF point　⇒ The domain where nucleate boiling is dominant Uncontrollable by the flow velocity ⇒ The forced convection is dominant　⇒ (1) Flow velocity ⇒ up (2) Heat flux ⇒ down Flow velocity Log⊿T Cancer Intelligence Care Systems, Inc, 2014

Cancer Intelligence Care Systems, Inc., 2014 Flow velocity ⇒ up Required cooling-water conditions Cancer Intelligence Care Systems, Inc., 2014

Cancer Intelligence Care Systems, Inc, 2014 Heat flux ⇒ down Optimization of target-base and its design Form change + beam irradiation conditions original case 1 case 2 case 3 case 4 case 5 case 6 case 7 case 8 case 9 case 10 case 11 case 12 case 13 case 14 case 15 Heat transfer suface(%) 100 117 134 185 213 265 238 144 192 129 115 166 193 162 178 Flow verocity (%) 98 102 111 67 143 95 116 107 max Temparture (℃) 153 135 128 123 120 119 142 141 122 138 131 130 Pressure drop (MPs) 0.89 2.05 1.54 10.9 1.18 1.44 1.69 1.2 0.91 1.67 1.1 1.55 1.39 1.68 1.7 1.76 trench width trench depth number of trench spiral pitch length Cancer Intelligence Care Systems, Inc, 2014

Target Cooling System: 8-inlet manifolds Flow rate(L/min) Pressure (MPa) Measu. Measu. Total Average Cancer Intelligence Care Systems, Inc., 2014

Cancer Intelligence Care Systems, Inc., 2014 Evaluation of Lithium Target System　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 calculated by PHITS 2.16 Cancer Intelligence Care Systems, Inc., 2014

Lithium Recovery System Moderator Reflector VTSM Gate Valve Beam Tube Target

Cancer Intelligence Care Systems, Inc, 2014 Conclusion Combination of low-energy proton beam 2.5MeV and Li-target is feasible, and each elements are going toward safety-alliance based on a basic design for the solid 7Li-target device. We should follow IAEA-TECDOC-1223　(May 2001) “Current Status of neutron capture therapy”, in which the definition of epi-thermal neutron < 10KeV can be accomplished by using the 2.5MeV of low-energy proton beam with 20mA. 7Be (half life 53.12 days) produced in the Li target should be disposed protectively, thus we can perform ABENS-BNCT safely. This new machine and building are completed to Summer 2014 in NCC in Tokyo. Cancer Intelligence Care Systems, Inc, 2014

Cancer Intelligence Care Systems, Inc, 2014 On behalf of many collaborators. Thank you very much for your attention! Cancer Intelligence Care Systems, Inc, 2014