Application of best estimate plus uncertainty in review of research reactor safety analysis

To construct and operate a nuclear research reactor, the licensee is required to obtain the authorization from the regulatory body. One of the tasks of the regulatory authority is to verify that the safety analysis fulfils safety requirements. Historically, the compliance with safety requirements was assessed using a deterministic approach and conservative assumptions. This provides sufficient safety margins with respect to the licensing limits on boundary and operational conditions. Conservative assumptions were introduced into safety analysis to account for the uncertainty associated with lack of knowledge. With the introduction of best estimate computational tools, safety analyses are usually carried out using the best estimate approach. Results of such analyses can be accepted by the regulatory authority only if appropriate uncertainty evaluation is carried out. Best estimate computer codes are capable of providing more realistic information on the status of the plant, allowing the prediction of real safety margins. The best estimate plus uncertainty approach has proven to be reliable and viable of supplying realistic results if all conditions are carefully followed. This paper, therefore, presents this concept and its possible application to research reactor safety analysis. The aim of the paper is to investigate the unprotected loss-of-flow transients "core blockage" of a miniature neutron source research reactor by applying best estimate plus uncertainty methodology. The results of our calculations show that the temperatures in the core are within the safety limits and do not pose any significant threat to the reactor, as far as the melting of the cladding is concerned. The work also discusses the methodology of the best estimate plus uncertainty approach when applied to the safety analysis of research reactors for licensing purposes

The correlation between body weight, body weight gain and blood parameters in pigs at birth and weaning

ABSTRACT The aim of study was to determine the relationship between metabolic parameters, body weight and body growth of piglets at birth and weaning. The experiment included 80 piglets obtained from F1 generation sows. Body weight was measured at birth (BW0), 24h (BW1) after birth and on day 25 (at weaning, BW2). Blood sampling was performed at the beginning of life (3rd day after birth) and at weaning (21st day after birth). BW0 and BW1 positively correlated with cholesterol and negatively with urea values at the beginning of life and RBC values at weaning. BW2 positively correlates with albumin and cortisol values at the beginning of life, total proteins, and globulins at weaning, and negatively correlates with erythrocyte values at weaning. Piglet growth from birth to weaning (BWG2-0) correlates positively with total proteins, albumin, and cortisol at the beginning of life and total proteins at weaning. ROC analysis shows that MCHC, TPROT, GLOB, CHOL and AST at the beginning of life can distinguish fast-growing from slow-growing piglets from birth to weaning period. The use of blood parameters enables early recognition of growth rate in piglets, which can help to optimize all further steps to achieve the best possible growth

Structure and mineral element composition of the lyophilised freshwater bryozoan Hyallinela punctata

Structure of the lyophilised colonies of the freshwater bryozoan Hyalinella punctata (Hancock, 1850) and their mineral element composition were studied by X ray diffraction, scanning electron microscopy (SEM) and inductively coupled plasma (ICP) spectrometry for the first time ever. The X ray measurements showed amorphous structure of the bryozoan, while SEM indicated porous connected structure without regular structural motifs. Considerable presence of phosphorus (7949.69 μg/ml), sulphur (6204.7 μg/ml) and calcium (6139.58 μg/ml), as well as low heavy metal content was found by ICP. The obtained results jointly indicate the potential of the investigated animal species as a base for bioscaffolds and nanocompositesPhysical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

In vitro evaluation of the immunomodulatory and anticarcinogenic activity of the freshwater bryozoan hyalinella punctata methanolic extract

The immunomodulatory and anticarcinogenic activity of the freshwater bryozoan Hyalinella punctata methanolic extract (MEx) was evaluated in vitro on selected biosystems for the first time. Murine lymphocytes and macrophages were used for testing of MEx effects on cell proliferation and nitric oxide (NO) production, respectively, while human cancer cell lines were utilized for measuring its activity against cancer cells. The results suggest a strong and tissue-specific immunomodifying activity (IC50 values for inhibition of proliferation of lymph node and spleen-derived lymphocytes were 4.1 mu g/ml and 9.7 mu g/ml, respectively) and moderate anticancer activity of MEx (IC50 value for the MCF-7 cell line was 24.13 mu g/ml). Down-regulation of macrophage NO production was also obtained. The potential use of H. punctata-derived natural products for the treatment of human chronic inflammatory diseases and cancer is worthy of further investigation

Antimicrobial activity of the freshwater bryozoan hyalinella punctata (Hancock, 1850)

The antimicrobial activity of the freshwater bryozoan Hyalinella punctata (Hancock, 1850) was tested by microdilution method against eight bacteria and eight fungi for the first time. All five crude extracts (hexane, acetone, dimethyl sulfoxide, methanol and water) showed good antibacterial and antifungal potential in vitro wherein the acetone extract was the most active (MICs 0.50-7.00 mu g/ml and MBCs 2.50-10.00 mu g/ml)

FONESYS : The Forum & Network of SYStem Thermal-Hydraulic Codes in Nuclear Reactor Thermal-Hydraulics

tThe purpose of this article is to present briefly the project called Forum & Network of System Thermal-Hydraulics Codes in Nuclear Reactor Thermal-Hydraulics (FONESYS), its participants, the motivation forthe project, its main targets and working modalities.System Thermal-Hydraulics (SYS-TH) codes, also as part of the Best Estimate Plus Uncertainty (BEPU)approaches, are expected to achieve a more-and-more relevant role in nuclear reactor technology, safetyand design. Namely, the number of code-users can easily be predicted to increase in the countries wherenuclear technology is exploited. Thus, the idea of establishing a forum and a network among the codedevelopers and with possible extension to code users has started to have major importance and value.In this framework the FONESYS initiative has been created. The main targets of FONESYS are:•To promote the use of SYS-TH Codes and the application of the BEPU approaches.•To establish acceptable and recognized procedures and thresholds for Verification and Validation (V&V).•To create a common ground for discussing envisaged improvements in various areas, including user-interface, and the connection with other numerical tools, including Computational Fluid Dynamics(CFD) Code