7 research outputs found
Reactivity Initiated Transient Response of TRIGA with the Progress of Core Burnt
No full textThis paper illustrates the effects on safety of TRIGA Mark-II research reactor of Bangladesh at its different steps of core burnt during reactivity induced transient. The modeling and simulation were carried by coupled point kinetics, neutronics, and thermal hydraulics code EUREKA-2/RR based on neutronics data calculated previously by Monte Carlo code for different burnt states of TRIGA core. Three burn steps until 150 MWD have been considered for present analysis which are regarded here as beginning of cycle (BOC); middle of cycle, MOC (75 MWD); and end of cycle, EOC (150 MWD). Initially, the results of steady state analysis obtained from EUREKA code for these three burn steps have been verified with that of COOLOD code. Based on consistency of the results from the two codes, transient simulation has been conducted considering reactor with non-function of scram. Reactivity inserted amount ranges within 0.001 to 0.02 dk/k with three durations of insertions of 0.1s, 1s, and 5s. Major parameters such as reactor core maximum power and fuel clad maximum temperature have been reported. The analysis presents transient pattern of these parameters due to change in amount and duration of inserted reactivity. The maximum imposed reactivity that causes the fuel clad to exceed its design temperature at each burn step has been evaluated in this study. It is also observed here for each amount and durations of inserted reactivity, maximum value of both power and clad temperature found to decrease with the progress of core burnt. These results obtained from this analysis will be useful for reactor operators and management team during core upgrading and modification program
Thermal Hydraulic Analysis of 3 MW TRIGA Research Reactor of Bangladesh Considering Different Cycles of Burnup
No full textBurnup dependent steady state thermal hydraulic analysis of TRIGA Mark-II research reactor has been carried out utilizing coupled point kinetics, neutronics and thermal hydraulics code EUREKA-2/RR. From the previous calculations of neutronics parameters including percentage burnup of individual fuel elements performed so far for 700 MWD burnt core of TRIGA reactor showed that the fuel rod predicted as hottest at the beginning of cycle (fresh core) was found to remain as the hottest until 200 MWD of burn, but, with the progress of core burn, the hottest rod was found to be shifted and another rod in the core became the hottest. The present study intends to evaluate the thermal hydraulic parameters of these hottest fuel rods at different cycles of burnup, from beginning to 700 MWD core burnt considering reactor operates under steady state condition. Peak fuel centerline temperature, maximum cladding and coolant temperatures of the hottest channels were calculated. It revealed that maximum temperature reported for fuel clad and fuel centerline found to lie below their melting points which indicate that there is no chance of burnout on the fuel cladding surface and no blister in the fuel meat throughout the considered cycles of core burnt
RIA Analysis of Unprotected TRIGA Reactor
No full textAn RIA (reactivity initiated accident) analysis has been carried out for the TRIGA Mark II research reactor considering both step and ramp reactivity ranges within 0.5 % dk/k (< 2). The insertion time was set at 10 s. Based on the fact that a reactor becomes unprotected if scram does not work at the event of danger, to define unprotected conditions, the time to actuate scram (trip) was taken as close to total simulation time. In this long duration of scram inactivity, it is obtained from the present analysis that the reactor remained safe to up to 1.8 % dk/k (2.84) for ramp reactivity. In addition to negative temperature coefficient of reativity, probably the longer time of reactivity insertion keeps TRIGA safe even at larger magnitudes of reactivity during unprotected reactor transients. Coupled point kinetics, neutronics, and thermal hydraulics code EUREKA-2/R has been utilized for this work. It appears that EUREKA-2/RR predicts the sequence of unprotected transient scenario of TRIGA core with good approximation and the results will definitely be helpful for the reactor operators.</p
A methodology for the reliability-based fracture assessment of structural components containing cracks
No full textFracture failure in piping systems is a common problem in the process industries, and the thesis describes the research that has been undertaken by the author in modelling and analysing a particular example of such a system, namely an expansion loop subjected to pressure and temperature loading. The work has been used to investigate the difficulties that arise in linking non-linear fracture mechanics analysis with reliability computations. The thesis includes a critical review of both linear and non-linear fracture mechanics and a separate review of advanced structural reliability methods. An improved response surface method has been proposed in this research to conduct a reliability assessment where the structural behaviour is modelled and the J-integral is computed using finite element software. Of particular interest has been the development of a methodology that is able to handle the non-linearities inherent in the material stress strain curve. Although it was possible to develop a response surface to achieve a good fit in the region of FROM/SORM design point, it led to instability in the FORM/SORM implementation. The research then focussed on the use of directional simulation as a solution technique for this class of problems. The material used in the construction of the expansion loop was AISI-321 stainless steel and to model this correctly in the reliability-based assessment the full range stress-strain behaviour was required in FE analysis. The material was tested in the laboratory and a new piecewise continuous stress-strain model has been developed which involves a linear-elastic part and two subsequent non-linear parts both of the Ramsberg-Osgood type. For the purposes of reliability assessment a new stochastic stress-strain model has been developed taking into account uncertainties in yield strength and in operating temperatures, together with the associated yield strength – temperature dependency. An integral part of the research has been a study of the J-integral profile along the crack front using 3-D FE analysis, for a number of CT (Compact Tension), beam and CCT (Central Crack Tension) specimens, with a range of thickness. This has brought new findings which are of importance in both deterministic and probabilistic assessment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
The Role of Women in The Rukyat Hilal According to The North Aceh Ulema Consultative Assembly
No full textThe Role of Women in Rukyat Hilal According to the Majelis Permusyawaratan Ulama Aceh Utara (MPU). Rukyat hilal is a method used to determine the beginning and end of the month of Kamariah. And along with the birth of the Falak Science study program in Indonesia, many also mastered falak science. One of the interesting things is the existence of female phallic experts and their role in determining the beginning of the Hijri month. This rukyat hilal activity is carried out collectively by the Ministry of Religious Affairs, the Ulema Consultative Assembly, BMKG and other community groups. From this background, the author is interested in studying the role of women in seeing hilal in North Aceh Regency based on the perspective of MPU. This research is a qualitative research, with a field approach (field research). The data collection method uses interview and documentation techniques. The results of this study show that the role of a woman in determining the beginning and end of the month in North Aceh according to the Majelis Permusyawaratan Ulama Aceh Utara there are two. First, if a woman is only a participant who participates in the Rukyat Hilal event, then this is allowed. Second, if a woman reports seeing hilal, then her testimony is not considered valid and rejected. Rukyat hilal merupakan suatu metode yang digunakan untuk menentukan awal dan akhir bulan Kamariah. Dan seiring lahirnya porgram studi Ilmu Falak di Indonesia, maka banyak pula yang menguasai ilmu falak. Salah satu hal yang menarik adalah keberadaan ahli falak perempuan dan perannya dalam penentuan awal bulan hijriyah. Kegiatan rukyat hilal ini dilakukan secara kolektif oleh Kementerian agama, Majelis Permusyawaratan Ulama, BMKG dan golongan masyarakat lainnya. Dari latar belakang tersebut, penulis tertarik mengkaji terkait peranan perempuan dalam melihat hilal di Kabupaten Aceh Utara berdasarkan perspektif MPU. Penelitian ini adalah penelitian kualitatif, dengan pendekatan lapangan (field research). Metode pengumpulan data menggunakan teknik wawancara dan dokumentasi. Hasil penelitian ini menunjukkan bahwa peran seorang perempuan dalam penentuan awal dan akhir bulan kamariah di Aceh Utara menurut Majelis Permusyawaratan Ulama Aceh Utara ada dua. Pertama, apabila seorang perempuan hanya sebagai peserta yang ikut dalam acara Rukyat Hilal, maka hal ini diperbolehkan. Kedua, jika seorang perempuan tersebut melapor melihat hilal, maka kesaksiannya tidak dianggap sah dan ditolak
