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case: the sample of infinite size. Radicals of any low concentration will then react sooner or later: ñcrit≈0; but, as higher concentration as sooner process of recombination begins). T0 - value can be evaluated from the relation ñcrit = R τ (1- exp(-T0/τ)), where τ and R are “life time “ of radicals and radical production rate, respectively. For low dose rate (and low value of R accordingly) and/or big volume of a sample, T0 may prevail over TSB resulting in deterministic character of SB appearance (if such is principally possible, that is, if ñcrit < R τ ). T0 will also prevail over TSB for high dose rate and big volume of a sample, situation which is typical for cold moderators of advanced spallation neutron sources. We understand that there are certain arbitrariness in the procedures used above. But it seems reasonable accounting for general conditionality of the model discussed. Function (1) is only one of many possible type of distribution of radicals in small volume of definite size chosen at random. Actually, type of the distribution is defined by many factors, such as structural defects, micro-cracks, crystallite interstitials, and diffusion of radicals which are quite unlikely to be analyzed with enough degree of certainty. This model may serve only for rough estimation of probability of spontaneous burping in solid methane and water ice until more rigorous theory is developed. REFERENCES 1. .Carpenter. Thermally activated release of stored chemical energy in cryogenic media. Nature, 1987, n 330, n 6146, p.358-360. 2. S. Ikeda, N.Watanabe, S.Satoh et al, In : Proc. of International Collaboration on Advanced Neutron Sources (ICANS-IX). PSI, Willigen, 1986, v.II,p.18--227 3. A.A.Belyakov, V.V.Melikhov, Yu.N.Pepelyoshev,E.P.Shabalin. “Solid methane cold moderator at the IBR-2 reactor". Journal of Neutron Research, Vol.3, 1996, pp. 209- 221. 4. E.P.Shabalin. On the Phenomenon of the Fast Release of Energy in Irradiated Solid Methane. Part I and II. JINR Communications, 1995. E17-95-141 and E17-95-142. 5. E. Shabalin, V. Golikov, S. Kulikov, L. Golovanov,V. Melikhov, E. Kulagin, A. Belyakov, V. Ermilov, V. Konstantinov, A. Androsov, Yu. Borzunov. Study of radiation effects in hydrogenous moderator materials at low temperatures. Presented at ACoM 6 Meeting. 6. E.Shabalin, S. Kulikov, V. Melikhov. Study of fast neutron effects in cold moderator materials. Particles and Nuclei, N5 [114], 2003, p.82-88. http://www1.jinr.ru/Pepan_letters/panl_5_2002/09_shab.pdf 7. D.A.Frank-Kamenetski. Diffusion & Heat Transfer in Chemical Kinetics (in Russian). Moscow, "Nauka", 1969. 8. J.L.Jackson. Dynamic Stability of Frozen Radicals. The Journal of Chemical Physics. V.31,1959, p.154-157,p.722-730 9. A.G.Merzhanov, V.V. Barzyikin, V.T. Gontkovskaya. ”Dokladi Acad. Nauk SSSR” (in Russian), V.148, p.380. 10. V.V. Barelko, I.M. Barkalov, V.I. Goldanskii, D.P. Kiryukhin, A.M. Znin. Adv. Chem. Phys., V.74, p.333 (1988). 194
11. V.I. Goldanski, E.N. Rumanov, E.P. Shabalin. The limits of propagation of the wave of recombinations of radicals. “The Chemical Physics” (Russian journal), 1999, V. 18, No 6, p. 16-20. Presented at the Fall 1999 Meeting of the American Chemical Society in New Orleans, August 22-26, 1999. 12. E.P.Shabalin. Consideration of the “Burp” Phenomenon in Solid Methane Accounting for Nonuniform Distribution of Irradiation Defects. In: Proc. of the Workshop on Cold Moderators for Pulsed Neutron Sources, Argonne, Illinois, ANL, 28 Sep.-2 Oct. 1997. ANL-Report. 13. E.P.Shabalin. On radiation effects in water ice at low temperatures. In: Proc. of the ICANS-XIV Meeting, June 1998, Starved Rock, Illinois, USA. ANL-98/33, V.2, p.497-506. 14. J.Carpenter. Cold moderator for pulsed neutron sources. In: Proc. of Intern. Workshop on Cold Neutron Sources. LANCE, Los-Alamos, US, 1990, LA-12146C. p 131-153. 15. Peter H. Hobbs. ‘Ice Physics’. Clarendon Press, N.Y.-London, 1974. 16. A.A. Beljakov, V.G. Ermilov, V.L. Lomidze et al. In: Proc. of ICANS--XII, RAL Report 94--025, v.II, p.144--155 17. E.P. Shabalin, A.A. Beljakov, V.G. Ermilov, V.V. Melikhov. In: "Advanced Pulsed Neutron Sources". Proc. of PANS II, Dubna, 14-17 June 1994. JINR Communications, Dubna, 1995. 18. E. Shabalin, H. Ullmaier, G.S. Bauer et al. URAM-2: Irradiation Experiments at the Dubna IBR-2 Reactor. Report ESS 99-92-T, July 1999. 195
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ACoM - 6 6th 6 International Worksh
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Forschungszentrum Jülich GmbH Inst
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Preface These are the Proceedings o
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List of participants, cont’d. Kü
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Pepe M. 43 Petriw S. 43 Picton D.J.
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Experimental background, results an
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• Light water ice as H(H2O) at T
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In Table 2 a survey is given about
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sigma-T in barns/molecule Figure 4.
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2.3 Liquid water Compared to the so
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presented. The corresponding experi
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3.2 Gaseous hydrogen and deuterium
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Rho(Omega) normalised 160 140 120 1
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elatively free and can also suffer
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Figure 16. Heat Capacity for Solid
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o-D2 and p-H2 at 5K for an ucn ener
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Figure 22. UCN Upscattering Rates i
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ho(omega) normalised 40 35 30 25 20
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derived from Walker [52]. The neutr
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Since there is only a small gain of
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7. CALCULATION OF SCATTERING LAW DA
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For the validation of these data se
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[36] Nielsen, M.: Phonons in Solid
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2. THE CASE OF MOLECULAR SOLIDS An
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γ r ( 0) ≅ 2 2 2 T erf e ( ) / 2
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4. PRELIMINARY APPLICATION Solid Me
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[5] Meeting on Moderator Concepts a
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state. Conversely, the monatomic hy
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Note that the equilibrium trihydrog
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para hydrogen system under irradiat
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[12] T. E. Fessler and J. W. Blue,
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tion of neutron intensities, partic
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varied between calculations but the
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5. THE OPTIMISATION OF MULTIPLY GRO
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Figure 7. A comparison of time dist
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4.8 cm hydrogen slab in front of a
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ACoM - 6 6 th Meeting of the Collab
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the moderator is annealed every 12
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The method requires two additional
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ABSTRACT ACoM - 6 6 th Meeting of t
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Heat transfer processes across phas
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3. TWO-PHASE FLOW PATTERN IN THE MO
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continuous phase dominating, and a
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Also the velocity pattern has chang
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Figure 8. Methane pellets concentra
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ACoM - 6 6 th Meeting of the Collab
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sample volume and the nominal densi
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The results presented in this paper
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Table 10. Summary of energy transfe
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2. EXPERIMENTAL Methane hydrate was
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Figure 4. Energy levels of methane
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102
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phase transitions from phase II to
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After melting phase I in the cryost
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4. SOLID PHASES OF MESITYLENE-D0 AN
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G(ν) [a.u.] 8 6 4 2 Phase II Phase
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112
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A not quite as perfect cold spectru
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2.2 Inelastic neutron scattering Th
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Figure 4. Inelastic spectra at the
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3.2 Moderator performance The resul
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122
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Figure 2. The methane pelletizer, m
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Figure 5. The cryogenic hopper fill
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128
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ture
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The charging device scheme could be
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Table 1. Data of irradiation of met
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5. METHODS OF PROCESSING OF RAW EXP
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of radicals, that is, before a burp
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6.2 Condition for thermally stimula
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Table 4. Estimated values of an ene
Page 148 and 149: • Nine spontaneous burps were obs
Page 150 and 151: APPENDIX Some useful relations and
Page 152 and 153: APPENDIX. Graphs of burps. 148
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Page 160 and 161: 2. EXPERIMENTAL SETUP Fig. 1 will g
Page 162 and 163: All these parameters are kept const
Page 164 and 165: 4. CONCLUSIONS We demonstrated that
Page 166 and 167: JESSICA (Juelich Experimental Spall
Page 168 and 169: The moderator system consists of th
Page 170 and 171: to change the temperatures and to p
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Page 174 and 175: supplied from the high pressure bom
Page 176 and 177: 10 9 10 8 10 7 10 6 Para35%[Experim
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Page 180 and 181: 2. TIME OF FLIGHT SPECTRA AND ENERG
Page 182 and 183: When applying this transformation t
Page 184 and 185: data were analyzed in more detail.
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Page 188 and 189: First of all, we should conclude th
Page 190 and 191: The equation (a) may also describe
Page 192 and 193: Even at h=0.01 mm which is too smal
Page 194 and 195: model and some consequences of its
Page 196 and 197: methane and 0.7-1.5% for water ice
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Page 216 and 217: Phase Diagram of the CH4-H20 system
Page 218 and 219: Reaction Chamber for Hydrate Produc
Page 220 and 221: Analysis: X-ray diffraction pattern
Page 222 and 223: Comparison with non-hydrate forming
Page 224 and 225: Mechanical Tests: Apparatus 220
Page 226 and 227: Morphology of Indium Jacket 222
Page 228 and 229: Schriften des Forschungszentrums J
Page 230 and 231: Schriften des Forschungszentrums J
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