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Title:	Characterisation of neutron flux parameters at Triga Mark II reator using K0-Inaa and absolute methods and comparison with MNCP-4C code
Authors:	Alireza Yavar (P47382)
Supervisor:	Khoo Kok Siong, Dr.
Keywords:	Neutron flux parameters Triga Mark II reator using K0-Inaa Absolute methods MNCP-4C code Nuclear activation analysis
Issue Date:	1-Dec-2012
Description:	The single comparator method known as the k0- instrumental neutron activation analysis (k0-INAA) is basically based on the Høgdahl-convention for (n, γ) reactions rate. The Høgdahl convention requires the (n, γ) cross section to vary to a good approximation as 1/ v up to 1.5 eV, but it becomes a challenging problem when dealing with non-1/ v (n, γ) reactions. For this reason, the modified Westcott convention is proposed at the Malaysian Nuclear Agency (MNA) TRIGA Mark II reactor. The present work showed the development of k0-INAA method using the Høgdahl-convention and Westcott convention according to "1/ v and non-1/ v (n, γ)" reaction nuclides at MNA research reactor. The neutron spectrum parameters such as thermal to epithermal neutron flux ratio ( f ), epithermal neutron flux shape factor (α ), thermal neutron flux ( Φth ) and epithermal neutron flux ( Φepi ) were measured using the Høgdahl-convention. The modified spectral index 0 r(α) Tn To ; the Westcott gLu (Tn) factor and the absolute neutron temperature n T parameters were determined using the Westcott-formalism at the reactor. The 176Lu as non-1/ vmonitor and 197Au, 96Zr and 94Zr as 1/ vmonitors were utilised. The average values of the f , α , Φth and Φepi were 19.10±3.92, 0.018±0.028, (2.32±0.19) ×1012 n cm-2 s-1 and (1.26±0.26) ×1011 n cm-2 s-1, respectively. The average values of 0 r( α) Tn / T0 , gLu (Tn) and Tn were obtained as 0.1795±0.0112, 1.9729±0.0931 and 50.12±12.76 °C, respectively. The accuracy of the method was evaluated by utilising IAEA-SL 1, IAEA-Soil 7, IAEASoil 375, and NBS SRM 1633A-1 as reference materials. The results showed an acceptable level of consistency. Determination of thermal to fast neutron flux ratio ( fast f ) and fast neutron flux ( Φfast ) are required for such purposes for radionuclide production by fast neutron reactions, application of fast neutron activation analysis (FNAA), and for correcting interference reactions. Forty rotary rack (RR) irradiation channels of the reactor were used for the determination of f fast and Φfast using the absolute method on 54Fe(n, p)54Mn and 96Zr(n, γ)97Zr/97mNb reactions. The values of fast f ranged from 48 to 155 with relative standard deviation (RSD) of 21.37%, and the values of f fast were found in the range of 1.03×1010 to 4.89×1010 n cm-2 s-1 with RSD of 16.75%. Simulation of the reactor by MCNP code can be very helpful with the aim of assessing the findings of research groups at the reactor. The reactor was modeled using the MCNP - 4C code in order to calculate the , Φth , Φepi , Φfast, f and f fast in 40 RR irradiation channels. The average values of , Φth, Φepi and Φfast by MCNP code were (2.19±0.03) ×1012 n cm-2 s-1, (1.26±0.02) ×1011 n cm-2 s-1, and (3.33±0.02) ×1010 n cm-2 s-1, respectively. Good agreement has been found between the measured results by k0-INAA method and MCNP code. This effort has produced a complete simulation of the calculated neutron flux parameters in 40 RR irradiation channels. This simulation can be used by research groups in the applications of reactor physics and neutron activation analysis for future work on the Triga reactor.,Ph.D
Pages:	188
Call Number:	QD606.Y348 2012
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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