In this work, a numerical model is proposed to estimate air concentration of released airborne radioactive contaminants
131
I and
137
Cs. A Gaussian dispersion model is used to assess the atmospheric ...dispersion of radioactive contaminants released continuously from a nuclear power plant as a result of an accident. The model uses various input parameters such as source height, release rate, stability class, wind speed, and wind direction. The validation of the model was carried out by comparing its predicted values with published experimental data. The model was extensively tested by simulating several accidental situations. The main conclusion drawn from these tests is that for large downwind distances from the release point, the contaminant concentrations predicted by the model diverge drastically from measured data, while for short distances, the predicted values generally agree quite well with experimental data. The obtained activity concentrations range from 1.57 × 10
2
to 6.43 × 10
3
Bq/m
3
for
131
I and from 3.18 × 10
−2
to 9.72 × 10
2
Bq/m
3
for
137
Cs. The estimated standard deviation coefficients values range of 7.2 to 6847.7 m, and the maximum absolute error predicted by the model for these parameters was less than 5%.
One of the major challenges in instrumentation is to identify wrong data (signal) measurements and perform their validation. This can be done by regularly ensuring a correct operation of the ...different process components, particularly those having great importance for safety, in order to detect, isolate and identify any possible degradation or fault. This operation, known as on-line fault monitoring, should be done as early as possible, before any fault causes failure in equipment which can lead to the downtime of the plant and even to severe catastrophes and disasters. Therefore, these consequences influence negatively on productivity, availability and environment.
At Triga-Mark II nuclear research reactor, the heat exchangers are provided for removing generated heat from the reactor pool water throw cooling circuits. Therefore, the monitoring of the evolution of certain thermo hydraulic parameters is necessary to ensure the safety of the reactor.
Among several developed techniques, analytical redundancy has been recognized as an effective method for fault monitoring. It is the process of identifying a faulty instrument in a system through a comparison of its output to an estimate data. This estimation is based on the model and the measurements provided by the data acquisition chains of the existing sensors during all the operating modes of the installation. In our case, we are limited to mathematical models and Kalman filter approaches.
In this paper we review the state of the fault monitoring and some model based analytical redundancy techniques for the heat exchanger, and present experimental results on their application to temperatures and flow rates of the cooling system of Triga-Mark II research reactor core.
This study is a contribution for radiation dose calculations of a hypothetical accident of a 1 MW research reactor Triga Mark II using HotSpot code. A postulated accidental release of noble gases and ...halogens were considered. The total effective dose (TED) was estimated for 1 day and 50 years after release. The total damage of fuel element cladding with a maximum radioactivity was considered. The obtained results show minimal TED values at the beginning of the release and at a shorter distance from the source. The maximum calculation results are acceptable and below the recommended public dose limit.
The radiological consequences of a potential atmospheric release of
131
I,
137
Cs,
133
Xe and
90
Sr for hypothetical accident appropriate to a 10 MW research reactor were calculated. The Gaussian ...model CROM (Screening Model for Environmental Assessment) was used to compute the accidental radioactive release under emergency exposure situation and the estimation of yearly average dose by different exposure pathways. The realistic assessment of radiation level due to the abnormal occurrence operation of nuclear installations such as foods consumption, external irradiation, inhalation and ingestion has been examined. In this study, the evaluation of the dose results, to a continuous emissions rate under dry and wet deposition process, was estimated onto six reference groups of public covering the period from the new born infant to more than 17 years old as defined by the International Commission on Radiological Protection. The obtained modeling results were compared to the limits values prescribed by IAEA and Euratom recommendations. The findings indicate that the ground concentrations were found to be significant and mostly sensitive to the emission conditions, when the total deposition exceeds the contamination limits. The short-lived isotopes have much more influence on the concentration on foodstuff. The activity concentration of
131
I is significantly higher in animal products and vegetables, while the
137
Cs is dominant in fruits vegetables. In contrast, the Noble gas
133
Xe is significantly lower.
This paper deals with the reliability assessment of electrical power supply systems under redundancy. For doing so, three probabilistic safety analysis (PSA) methods are proposed and developed namely ...fault tree analysis (FTA), reliability block diagram (RBD), and Monte Carlo Simulation (MC) method. The FTA method is performed using RiskSpectrumPSA® software and the RBD and MC methods are coded using Matlab software. The electrical power supply system reliability is analyzed and enhanced considering various cases of redundancy. The FTA method is based on qualitative and quantitative reliability assessment. The quantitative assessment calculates the failure probability of the top event, and the qualitative approach determines the minimal cut sets (MCS). However, the RBD and MC methods are proposed to compute the system failure probability. The considered methods are applied on three case studies and the obtained results are compared to each other. The obtained results show that the three methods provide almost the same results. Furthermore, the reliability of the electrical power supply is clearly enhanced with the number of redundant components.
Ovo istraživanje doprinos je izračunima doze zračenja hipotetske nesreće istraživačkog reaktora Triga Mark II od 1 MW primjenom HotSpot koda. Razmatrano je slučajno oslobađanje plemenitih plinova i ...halogena. Određena je vrijednost ukupne učinkovite doze nakon 1 dana i nakon 50 godina. Razmatrano je ukupno oštećenje obloge dijela s maksimalnom radioaktivnošću. Dobiveni rezultati pokazuju minimalne vrijednosti ukupne učinkovite doze na početku ispuštanja i na manjoj udaljenosti od izvora. Maksimalni rezultati izračuna su prihvatljivi i ispod preporučenog doznog ograničenja.
