Current Status of Spallation Product Data V.Artisyuk, T.Sawada, M.Saito Tokyo Institute of Technology Research Lab. For Nucl. Reactors

Neutron production in ADS Accelerated charged particles Spallation target neutrons

Code Validation Sequence Experiments Bulk Target Thin target (foils) Integral Characteristics Spatial Distributions Mass Distribution of Spallation Products Accumulation of Selected Nuclides Total Neutron Production Heat Deposition Radioactivity accumulation Transport Phenomena Nuclear Models

Comparison of CASCADE/OINPE and ATRAS Codes I Experimental Model* Activation Detectors R=10 cm Proton Beam Lead Target 3µA, 1 GeV 60 cm *Bakhmutkin S.B., et al, Measuremnts of Nuclides Produced in a Leadt Traget Irradiated by 1 GeV Protons, Sov.Journ., Atomnaya Energija, v.63, 1987, p.137-140

Experiment:S.Bakhmutkin et al, Sov.J. Atomic Energy, 1987, v.33 S.Takaya, V.Artisyuk, A.Stankovskii, M.Saito, Yu.Korovin, Validation of Accelerator-Driven Transmutation Code System ATRAS, 2000 Spring Meeting of the Atomic Energy Society of Japan; O-49 Experiment:S.Bakhmutkin et al, Sov.J. Atomic Energy, 1987, v.33

Spallation products distribution by charge number Z Taken from: G.J.Russell, et al, Introduction to Spallation Physics and Spallation Target Design, Proc.Int.Conf. On Accelerator-Driven Transmutation Technologies and Applications, Las Vegas, NV, 1994, p.96 Taken from: G.S.Bauer, Physics and technology of spallation neutron sources, Nucl.Instr.Meth. A463 (2001) 505-543 “It can be seen that, although in small quantities, most elements of the periodic table are generated in a heavy spallation target. The consequences this has on materials properties and possible reactions is not yet well explored”

Spallation products mass distribution Fig.2. Residue mass production weights for p-induced reactions on a thick cylindrical natPb target (L=100 cm, R=10 cm) at 1 GeV incident energy. Fig.1. Residue mass production cross-sections for p(1GeV)+208Pb reactions. Taken from: L.Donadille, et al, Impact of Various Models on the Production of Spallation Residue Yields and Target Activation, Internal Report of DSM/DAPNIA/SPhN, C.E.A. Saclay, F-91191 Gif-sur-Yvette, France (2002)

Mass Distribution of Spallation Products (KASCADE Code)

On the Status of Fission Products and Spallation Products G.R.Keepin, Pjysics of Nuclear Kinetics, Addison-Wesley Publishing Co, 1965 1.0 GeV+ 208Pb Titarnko et al, Rusiia, 1999: About 800 nuclides identified with gamma spectrometry technique “The measurement of some 120 fission products has now resulted in a reasonably accurate picture of the distribution of mass and cahrge in fission of the major fuels” 208Pb (208 Gev)+H Wlazlo et al, Europe, 1999: More than 1000 nuclides measured with magnetic spectrometry

Current status in getting the Spallation Products: Current status in getting the Reasonably accurate picture of the distributions What do we have now? Picture of the distribution? Accurate picture of the distribution? What does it mean: “Reasonably accurate picture of distribution”?

Accurate Picture of Distributions? Comparison of the computer codes’ predictive power <..> =Σi fi i i -production cross-section of i-type nuclide Computer code Code reference F-value LAHET (ISABEL) R.E.Prael and H.Lichtenstein, LA-UR-89-3014 (1989) 1.92 CEM2k S.G.Mashnik, et al, Proc. 5-th Intern. Workshop on Simulating Accelerator Radiation Environments, OECD Headquarters, Paris, France, July 17-18 (2000) 1.62 CASCADE V.S.Barashenkov, et al, JINR, R2-85-173, Dubna, Russia (1985) 2.18 YIELDX R.Silberberg, et al, Astrophys. J., 501, 911 (1998) 2.76 INUCL G.A.Lobov, et al, ITEP-91, Moscow, Russia (1983) 2.89 CASCADE/INPE V.S.Barashenkov et al, Atomnaya Energiya, 87,283 (1999) (in Rus) 1.85

Code Validation * Wlazlo et al., ADTTA’99, Prague, 1999 Exp * CASCADE/INPE Bertini ISABEL Dresner GSI MCNPX (LAHET mode) MCNPX (CEM mode) MCNPX 2.5 (CEM2K improved) * Wlazlo et al., ADTTA’99, Prague, 1999

Quality of cumulative yield cross-sections obtained with CASCADE/INPE code

Spallation products: mass distribution and toxicity* Fission and evaporation products Light nuclides Heavy nuclides * Annual Limit on Intake (ALI) - is the annual intake of a given radionuclide by "Reference Man" which would result in either a committed effective dose equivalent of 5 rems (stochastic ALI) or a committed dose equivalent of 50 rems to an organ or tissue (non-stochastic ALI)** 3H, -decay, ALI= 3.0 x109 Bq 99Tc, -decay, ALI= 2.0 x107 Bq 210Po, -decay, ALI= 2.2 x104 Bq Rare earths region ** CFR.20.B - The Code of Federal Regulations, Part 20: Standards for Protection Against Radiation, Appendix B Reference model protons Pb-Bi 1m 1m

Fragment of Chart of the Nuclides Containing Rare Earths 20 60 100 140 40 80 Z N 152Gd 1.1x1014y 148Gd 74.6 y 154Dy 3x106y 150Gd 1.79x106y 148Sm 7.x1015y 147Sm 1.1x1011y 146Sm 1.03x108y 144Nd 2.3x1015y 143Nd 12.18 145Nd 8.30 146Nd 17.19 147Nd 10.98 d 148Nd 5.76 144Pm 363 d 145Pm 17.7 y 146Pm 5.53 y 147Pm 2.62 y 148Pm 41.29d 5.370 d 149Pm 2.212 d 145Sm 340 d 149Sm 13.8 150Sm 7.4 148Eu 54.5 d 151Eu 47.8 146Eu 4.59 d 147Eu 24.1 d 149Eu 93.1 d 150Eu 36.9 y 12.8 h 147Gd 38.06 h 151Gd 124 d 149Gd 9.28 d 148Tb 1.08 h 2.30 m 149Tb 4.118 h 4.16 m 150Tb 3.48 h 5.8 m 151Tb 17.609 h 25 s 152Tb 17.5 h 4.2 m 153Tb 2.34 d 152Dy 2.38 h 153Dy 6.4 h 155Dy 9.9 h 149Dy 4.20 m 0.49 s 150Dy 7.17 m stable 30d<T1/2<5x108y 10m<T1/2<30d T1/2<10m 99.9% <  +  99.9% < 

On Mechanism of Rare Earths’ Accumulation Characteristics of the predecessors of RE alpha-emitters accumulated in various targets irradiated by 1.6 GeV protons Characteristics of predecessor Target Tungsten Lead Uranium Fragment: 146Sm Yield (at/p) 8.310-4 2.110-4 4.310-5 <Z> 70.0 76.7 88.0 <A> 174.2 193.8 222.1 <Eexc> 342.6 582.4 1005.3 Fragment: 148Gd 3.410-3 8.810-4 8.710-5 70.5 77.6 89.5 175.2 194.3 223.9 314.1 551.3 979.2 Probability to have an excitation energies around 1 GeV (uranium case) is much less than few hundred MeV (tungsten case) needed to evaporate enough nucleons and finally produce RE isotopes. It gives an additional argument that rare earths are the final fragments of evaporation process from excited state after intranuclear cascade reaction  

Target Design Options USA (ATW project) Lead-Bismuth “R&D efforts proposed include the design and operation of a Lead Bismuth Eutectic” A Report to Congress, October 1999, DOE/RW-0519 Lead-Tin eutectic (38.1Pb-61.9 Sn) “…this alloy does not produce any serious Po or toxic daughter material” J.PARK et al., Nucl. Eng. Des., 196 (2000) 315-325. Europe ( Energy Amplifier ): Lead “…the use of of Bismuth or of Bismuth-Lead eutectic mixture is not considered as the main coolant, since Bismuth via the leading single neutron capture produces sizable amounts of Polonium which is radio-toxic…” C.RUBBIA et al., IAEA-TECDOC-985 (1997) 187-313. JAERI (OMEGA project): Tungsten T.TAKIZUKA et al., IAEA-TECDOC-985 (1997) 187-313 Lead-Bismuth “A behaviour analysis of Po-210 and spallation products …will be necessary” K.TUJIMOTO et al, Progress in Nucl. Energy, v.37

Key Words and Points for Comparison Polonium Spallation Product Activity Toxicity

stress on short-lived nuclides Generated toxicity in p- Pb, p-W, and p-Sn interactions as a function of proton energy stress on short-lived nuclides Rare earth alpha emitter 148Gd (T1/2=74.6 yr) is identified as the dominating contributor into generated toxicity governed by short-lived nuclides: in p-W (380 – 1600 MeV) and p-Pb (800 – 1600 MeV) interactions

stress on long-lived nuclides Equilibrium toxicity resulted from p-Pb interaction as a function of proton energy ( associated beam current 1 mA) stress on long-lived nuclides Rare earth alpha emitters are identified as the most toxic long-lived nuclides

Time-dependent accumulation of key nuclides in bare Pb-Bi target* Inventory (at.) Activity (Bq) Toxicity (ALI) * diameter 1m, length 1 m. Proton beam: 1 GeV, 50 mA

On Importance of Spallation Products’ Accumulation ANS meeting, Washington DC, November 17-21, 2002 “ 148Gd Production Cross Section Measurements for Accelerator Target Facilities”, Karen Corzine, Eric Pitcher, Matt Devlin (L ANL), Nolan Hertel (Georgia Tech) p.542 ”The activity level of 148Gd is small, but it encompasses almost two thirds of the total dose burden in the LANSCE facilities based on present yield estimates.”

Improvement of the models for high energy interactions is a must. Current Status In view of insufficient experimental data on their yield in ADS target materials, computer simulation remains to be of importance. Computer codes reveal a large discrepancy particularly in the region of Rare Earths. Improvement of the models for high energy interactions is a must.