Kabach, Ouadie; Uzun, Sinem; Genç, Yasin; Uzun, Bedrettin; Chakir, El Mahjoub; Amsil, Hamid

Accident-tolerant fuel (ATF) concepts are being evaluated to strengthen margins without sacrificing core economics. This study compares five ATF matrices, UN (with natural and enriched nitrogen), UC, UCO, U3Si2, and UAl2, implemented in 17 × 17 solid and 13 × 13 dual-cooled annular PWR lattices. Results show that the multiplication factor decreases monotonically with burnup in both geometries, which allows the use of the linear reactivity model to predict the reactor cycle length; UAl2 and UO2 provide the longest cycles. Assembly-level radial peaking remains low (≈1.05–1.09). All fuel and moderator temperature coefficients are negative, with the strongest feedback in annular UN (Natural N). Solid pins show a single outer-rim power/Pu-239 peak; annular pins split this into two milder rims and flatten the in-pin profile. Prompt (neutron-induced) power is essentially burnup-invariant by normalization, while decay heat grows with matrix density and conversion. Thermal-hydraulic results show that the annular geometry lowers coolant heating and pressure drop and raises the minimum DNBR by ∼ 55–65% relative to solid pins under identical boundary conditions.

Polat, Recep; Içelli, Orhan; Yalçin, Zeynel; Pesen, Erhan; Orak, Salim

59.5 keV gamma rays scattered by an aluminum foil have been used as a radiation source to measure the absorption jump factor and jump ratios for absorbers Ce, Pr, Nd, Sm, Eu and Tb. The theoretical and experimental values are compared with the corresponding ones in the literature.

Şahin, Remzi; Polat, Recep; Içelli, Orhan; Çelik, Cafer

This study focuses on determination of transmission factors of main parameters affecting the properties of both normal- and heavy-weight concrete in order to increase knowledge and understanding of radiation attenuation in concrete at a later age. Water/cement (W/C) ratio, curing condition, cement quantity and air entraining agent (AEA) were selected as the main parameters. Eight energy values have been selected within the energy interval of 30.85-383.85 keV to be used in the radiation source. The Taguchi Method was used as the method of optimization. It was determined in the study that the most important parameter affecting the attenuation of the radiation of the concrete is the W/C ratio and the concretes produced with the lowest level of W/C ratio absorb more radiation. However, it was also determined that there was a combined effect between the W/C ratio and the cement dosage.

Içelli, Orhan

The differential attenuation coefficients for total scattering have been measured using the Si(Li) detector at photon excitation energy of 59.5 keV for Fe2O3, Y2O3, Nb2O5, SeO2, Sb2O5 and BaO compounds at seven angles ranging from 60° to 120° at intervals of 10°. The obtained results have been compared with relativistic and non-relativistic theoretical values.

Içelli, Orhan; Erzeneoǧlu, Salih; Saǧlam, Mustafa

Effective atomic numbers (Zeff) of polypyrrole have been determined for total photon interactions in the energy range 15.74-40.93 keV from the accurately measured total attenuation coefficients, for characteristic K and K X-rays of Zr, Mo, Ag, In, Sb, Ba and Pr. The results were compared with the theoretical atomic numbers obtained using the XCOM.

Içelli, Orhan

The linear differential scattering coefficients at 60 keV have been measured for UO2(C2H3O2)2 · 2H2O (uranyl-acetate) and Th(NO3)4 · 5H2O (thorium-nitrate) radioactive compounds at seven angles ranging from 60° to 120° at intervals 10°. The obtained results have been compared with relativistic and non-relativistic theoretical values.

Içelli, Orhan; Erzeneoǧlu, Salih; Boncukçuoǧlu, Recep

Measurements have been made to determine variation of the mass attenuation coefficients of H3BO3 according to percentage increasing concentration of H3BO3 by using an extremely narrow-collimated-beam transmission method in the energy range 15.746-40.930 keV with an X-ray transmission method. The characteristic Kα and Kβ X-rays of the different elements (Zr, Mo, Ag, In, Sb, Ba and Pr) passed through boric acid was detected with a high-resolution Si(Li) detector. Results are presented and discussed in this paper.