Research for Fast Neutron Absorbed by Materal for Fast Neutron Fluence Measurement TANG Xdng Nuclear Power Insttute of Chna tangxdng@yahoo.cn
Outlne 1 Am of ths Paper 2 Approxmate Analyss of the Influence of Fast Neutron Absorbed by the Cover 3 Total Cross Secton calculaton for X333 4 Reprocessng the Old Measured Data 5 Conclusons 2
1 Am To provde analyss and judgement data of old fast fluence measurement due to some nfluence of fast neutron absorbed by elements wasn t consdered, To fnd the method for usng the total cross secton from NDF JF JFF JNDL by X333 3
2 Fast Neutron Sheldng Influence Approxmate Analyss Only the total cross sectons of Cd,B,Gd are In IRDF, STAYNL code can only process the nfluence of the fast neutron absorbed by the three element,so we consdered only Cd and B n our experments. Many nucldes total cross secton value are almost same (fg.1~4), 2-6mm dffer materal s fast fltered ablty are about 4%-22%(table 1). thermal neutron flters( Cd,CdO,BN,B4C,Gd ) and packagng materal ( N, T, fg.5~7) absorb fast neutron almost n same ablty. 4
If consder other element (e.p. N,C,O) as Cd the thckness wll ncrease, and the absorbed fast neutron wll ncrease( table 2); In order to consder the nfluence of the fast neutron absorbed by all elements, the new total cross secton must be constructed and nsert nto IRDF; The constructed total cross secton n IRDF must be checked to show t s correct To reprocess old measured data by usng the new IRDF lb. for estmatng credtablty of the old measurement 5
6 NPIC NPIC Nuclear Power Insttute of Chna 3 Total Cross Secton Cal. for X333 372 group energy structure constructon element total cross secton calculaton ( )( ) ( ) < < + = = + + + e j e j e j e j e j e j e j e j e j e j 1 1 1 ( ) = k k k k k a a, '
= ( NPIC ( ) c nl e l Nuclear Power Insttute of Chna 3 Total Cross Secton Process for X333 compound total cross secton calculaton multlayer sheld total cross secton calculaton = ( ) n c l e l t = Zt c t t Z 7 t t Z Fe Fe
3 Total Cross Secton Process for X333 Total cross secton convertng from 372 group to 640 group SAND-II energy group structure 6 m = m+ 1 equvalent thckness calculaton of multlayer covers d ' = t φ φ m ρ Cd Cd m d ρ t t t m t 8
3 Total Cross Secton Cal. for X333 To check and valdate the new total cross secton nserted n IRDF, see table 3 and fg. 8~11.
4 Reprocessng the Old Measured Data Reprocess the measured data of GD2V and QS2-1A by usng the new IDRF lb., the rato of the new results to the old results are n table 4 and table 5, Consderng the nfluence of the fast neutron absorbed by all elements n covers (not subtracted by ron), the new results are larger 3.2% and 4.8% than olds, respectvely Consderng the nfluence of the fast neutron absorbed by all elements n covers and subtracted by ron, the new results s smaller 1.5% and 2.6% than olds, respectvely The old measurements are credtablty and safety. 10
5 Conclusons For fast neutron fluence rate measurement, the nfluence of fast neutrons absorbed by elements need to consder not only for these elements such as Cd, B, and Gd, but also for those elements, for example N, C, O, N, T, V,Al, and ought to subtract the replaced materal s nfluence from them. 11
Thanks 12
Table 1 N fast neutron attenuaton estmaton (0.1MeV 20MeV) T N B Cd Fe Gd Cd0 BN B4C F2mm 0.035 0.067 0.068 0.053 0.053 0.041 0.056 0.052 0.071 F 6mm 0.101 0.187 0.1 0.151 0.151 0.117 0.155 0.14 0.18 For dffer materal, fast neutron attenuaton ablty s dffer due to the total cross secton and densty s dffer 13
Table 2 Rato of fast neutron fluence of GD2V (thckness of Cd s dffer) F F 2.2 0 F F 3.2 0 F54P 1.02 1.03 NI58P 1.017 1.034 CU63A 1.025 1.05 NB3N 1.001 1.003 NP237F 1.066 1.138 U238F 1.06 1.125 Weghted 1.031 1.064 14
Table 3 devaton of calculated resonance ntegral from NDF s (%) B10 B11 CD106 CD108 CD110 CD111 CD112 CD113 CD114 CD116 CD NDF 6.6.15 8 13.85 3.43 3.24 4.6 7.38 3.47 6.6 3.7 372 0.1 0.4 0.48 0.68 0.22 0.36 0.85 0.13 0.35 0.58 0.3 C GD152 GD154 GD155 GD156 GD157 GD158 GD160 N14 N15 NI58 NDF 11.72 1.04 1.75 1.0 2.8 2.38 4.01 5.51 6.22 18.8 66.0 1 372 0.43-0.17 0.25-0.08 0.25 0.15-0.01 0.41 0 0.38 0.13 NI60 NI61 NI62 NI64 O16 TI46 TI47 TI48 TI4 TI50 T NDF 3.88 24.8 3.68 2.22.5 76.87 10.42 5.47 1.78 288.17 2.41 372 0.5 0.48 0.1 0.5 0.38 0.62 0.3 0.03 0.40 0.2 0.15 15
Table 4 Rato of fast neutron fluence rate Befor F54P of GNP-2V NI58P CU63A NB3N NP237 F 1.072 φ N + CdO U238F 1.053 φ Cd weghted 1.01 After 1.01 1.016 1.024 1.001 1.070 1.058 1.032 Befor F54P NI58P CU63A NB3N NP237 F 0.77 φn+ CdO Fe φ Cd U238F weghted 0.65 0.1 After 0.0 0.1 0.87 0. 0.78 0.63 0.85 16
Table 5 Rato of fast neutron fluence rate Befor After F54P 1.042 of QS2-1A NI58P 1.038 CU63A 1.041 NB3N 1.003 NP237 F 1.074 1.067 φ T + BN U238F 1.062 1.074 φ weghted 1.022 1.048 B Befor F54P NI58P CU63A NB3N NP237 F 0.60 φt+ BN Fe φ U238F 权 重 0.68 0.88 B After 0.76 0.78 0.77 0. 0.64 0.61 0.74 17
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