Development of computer software for neutron energy spectrum adjustment in research reactors

• Published in: Nuclear Technology and Radiation Protection Vol. 24; no. 1; pp. 13 - 17
• Main Authors: Iqbal, Masood, Mirza, Sikander, Khokhar, Bilal
• Format: Journal Article
• Language: English
• Published: VINCA Institute of Nuclear Sciences 01.04.2009
• Subjects: BUNKI; neutron spectrum; PARR-2; research reactors; spectrum adjustment
• ISSN: 1451-3994; 1452-8185
• DOI: 10.2298/NTRP0901013I

A computer program has been developed for neutron energy spectrum adjustment using the deconvolution method. The BUNKI-based algorithm has been implemented to converge quickly yielding calculated neutron energy spectrum which is in good agreement with theoretical predictions. The foil activation data have been used as an input for each unfolding technique and various activation foils including Au-197, Al-27, Ni-58, Co-59, and Mg-24 covering thermal to fast energy range have been utilized. The group cross-section values were derived from the data given in the pre-processed cross-section libraries in ENDF-6 format of IRDF-90/NMF-G. Firstly, virtual approach was used for neutron energy spectrum adjustment. In this case, the activity of foils before and after the adjustment was almost the same but the flux had the maximum error of 14%. Secondly, the experimental measured activity of the threshold foils was then used for a real system. The activity of the threshold foils before and after the neutron energy adjustment had the maximum error of 33%. Koriscenjem dekonvolucione metode razvijen je racunarski program za podesavanje neutronskog spektra. Upotrebljen je algoritam zasnovan na BUNKI proceduri, koji brzo konvergira i izracunava neutronski spektar u dobroj saglasnosti sa teorijskim predvidjanjima. Podaci o aktivaciji folija korisceni su u svakom dekonvolucionom postupku, a upotrebljene su razlicite aktivacione folije, ukljucujuci Au-197, Al-27, Ni-58, Co-59 i Mg-24, da pokriju podrucje od termickih do visokih energija. Vrednosti grupnih preseka izvedene su iz podataka sadrzanih u biblioteci preseka ENDF-6, u formatu IRDF-90/NMF-G. Za podesavanje neutronskog spektra najpre je koriscen virtuelan pristup. U ovom slucaju, aktivnost folija pre i posle podesavanja bila je skoro ista, ali sa maksimalnim odstupanjem fluksa od 14%. Zatim je, za realni sistem, koriscena eksperimentalno merena aktivnost prag folija. Pre i posle podesavanja neutronske energije, aktivnost prag folija maksimalno je odstupala 33%.