Valorisation of probabilistic seismic hazard results in Finland (VALERI)

Probabilistic seismic hazard analysis (PSHA) is the standard method to assess seismic hazard for nuclear power plants (NPPs). In Finland, the median confidence seismic hazard at annual frequency of exceedance (AFE) 10-5 is used for designbasis earthquake (DBE), with a minimum threshold of the horizontal peak-ground acceleration of 0.1g. Exceptional earthquakes for design extension conditions (DECC) are proposed with median confidence at AFE 10-7/year (STUK, 2019). In this work, we explore the possibilities of DBE being anchored to other confidence level hazards, since the use of median is the minority position in Europe. We outline PSHA as a tool for hazard calculations, and how hazards are used in risk assessment and risk-informed decision-making. We particularly focus on the treatment of uncertainties and arguments about the mean and fixed-confidence hazards. The goal is to probe if regulatory transition away from median confidence hazard is (i) desirable, (ii) possible and (iii) identify the foreseeable difficulties. We discuss possible options for DBE and DEC C, for the consideration of the different stakeholders. Since the use of median hazard has a long tradition in Finland, an update would be no trivial undertaking

Valorization of probabilistic seismic hazard results in Finland

Probabilistic seismic hazard analysis (PSHA) is currently the standard method for assessing seismic hazards for nuclear power plants (NPPs) in Finland. To obtain values of ground-motion parameters for design purposes, two decisions are made regarding which annual frequency of exceedance (AFE) should be adopted and from which hazard curve the ground-motion value should be read for the design-basis earthquake (DBE) and the design-extension condition earthquake (DEC EQ, DEC C for short). The current regulatory status in Finland, given in the guide YVL B.7 (STUK 2019) by the Radiation and Nuclear Safety Authority of Finland (STUK), is that the median- confidence seismic hazard at AFE 10−5 is used for DBEs at NPPs with a minimum horizontal peak-ground acceleration (PGA) of 0.1 g. The high variability of ground-motion shaking patterns and various examples of exceedance of the DBE ground motion from that of natural earthquakes throughout the world have resulted in upgrades to meet new definitions of the requirements for ground motion beyond that of DBEs. Exceptional earthquake effects, with an estimated frequency of occurrence less than 10−5/year are postulated in DEC C for NPPs in Finland. Here, we outline the PSHA and its consequent use in risk assessment and risk-informed decision-making. We review arguments about the mean and median hazard curves in the PSHA. We draw particularly on the outcomes of the SENSEI (SENsitivity study of SEIsmic hazard prediction in Finland) project conducted under the auspices of STUK in 2019−2020, present new figures based on the SENSEI set of hazard calculations, and analyze them. We focus on the ratio of the mean and median hazard of PGA, spectral acceleration at 1 Hz, 5 Hz, and 25 Hz at AFE levels 10−4, 10−5, 10−6, 10−7 and 10−8. We analyze possible options for DBE and DEC C for consideration of the various stakeholders. Since the use of median hazards has a long tradition in Finland, an update is no trivial undertaking. The suite of options is not necessarily exhaustive

Valorization of probabilistic seismic hazard results in Finland

Probabilistic seismic hazard analysis (PSHA) is currently the standard method for assessing seismic hazards for nuclear power plants (NPPs) in Finland. To obtain values of ground-motion parameters for design purposes, two decisions are made regarding which annual frequency of exceedance (AFE) should be adopted and from which hazard curve the ground-motion value should be read for the design-basis earthquake (DBE) and the design-extension condition earthquake (DEC EQ, DEC C for short). The current regulatory status in Finland, given in the guide YVL B.7 (STUK 2019) by the Radiation and Nuclear Safety Authority of Finland (STUK), is that the median- confidence seismic hazard at AFE 10−5 is used for DBEs at NPPs with a minimum horizontal peak-ground acceleration (PGA) of 0.1 g. The high variability of ground-motion shaking patterns and various examples of exceedance of the DBE ground motion from that of natural earthquakes throughout the world have resulted in upgrades to meet new definitions of the requirements for ground motion beyond that of DBEs. Exceptional earthquake effects, with an estimated frequency of occurrence less than 10−5/year are postulated in DEC C for NPPs in Finland. Here, we outline the PSHA and its consequent use in risk assessment and risk-informed decision-making. We review arguments about the mean and median hazard curves in the PSHA. We draw particularly on the outcomes of the SENSEI (SENsitivity study of SEIsmic hazard prediction in Finland) project conducted under the auspices of STUK in 2019−2020, present new figures based on the SENSEI set of hazard calculations, and analyze them. We focus on the ratio of the mean and median hazard of PGA, spectral acceleration at 1 Hz, 5 Hz, and 25 Hz at AFE levels 10−4, 10−5, 10−6, 10−7 and 10−8. We analyze possible options for DBE and DEC C for consideration of the various stakeholders. Since the use of median hazards has a long tradition in Finland, an update is no trivial undertaking. The suite of options is not necessarily exhaustive

Effect of Maternal Anaemia on APGAR Score of Newborn

Background: To study the effect of maternal anaemia on APGAR score of newborn and to compare it with that of non-anaemic mothers.Methods: In this cross sectional study 100 subjects were divided into two groups; each containing 50 subjects on the basis of consecutive non probability sampling . Group A included 50 anaemic pregnant women (haemoglobin < 11.0 g/dl) and group B 50 non-anaemic(haemoglobin >11.0 g/dl) pregnant women. In APGAR scoring five factors (which Apgar stands for) were used to calculate the baby’s condition and each scored on a scale of 0 to 2, with 2 being the best score.A baby who scored 8 or above was considered in good health and a score of less than 8 was considered low. Data was compared using t-test at a confidence level of 95%. Frequencies were calculated for categorical data. These were compared using chi-square test, and p<0.05 was statistically significant.Results: Difference between the two groups was found to be statistically very significant (p<0.003)in this variable also, as 16 out of 50 babies delivered to mothers in the anemic group showed a low APGAR at one minute as against 04 out of 50 in the babies delivered to the mothers in the non anemic group .Difference between the two groups was found to be statistically significant (p<0.012) . Twelve out of 50 babies delivered to mothers in the anemic group in our study showed a low APGAR at five minutes as against 03 out of 50 in the babies delivered to the mothers in the non anemic group.The number of anemic mothers who showed a low APGAR score of their infants were more at both one (32%) and five minutes (24%) as compared to the non anemic group (08% and 06% respectively), with a statistically highly significant difference of these two variables (p<0.003 and p<0.01 respectively) between the two groups.Conclusion: There was a linear relationship of maternal anaemia in pregnancy with greater probability of low APGAR score at one and five minutes

Probabilistic seismic hazard analysis in low-seismicity regions : An investigation of sensitivity with a focus on Finland

Online supplementary informationWe investigate probabilistic seismic hazard analysis (PSHA) in low-seismicity regions in which epistemic uncertainties are largely due to the sparsity of data, with a focus on Finland, northern Europe. We investigate the sensitivity of site-specific PSHA outcomes to different choices of basic input parameters, starting from preexisting PSHA models of the nuclear licensees in the country, without producing a final hazard curve. The outcome shows that the parameters and models needed to estimate future seismicity rates from actual observations, in particular the b value, seismicity rates, and the largest possible magnitude, Mmax, as well as the median ground-motion prediction equation, play significant roles. The sensitivity also depends on the spectral frequency; for example, the effect of Mmax is significant especially for a low-frequency hazard at annual frequency of exceedance 10−5 but more moderate for peak ground acceleration. The delineation of seismic source zones (SSZs) remains ambiguous in regions of low seismicity. This, combined with the dominance of the host SSZ and its seismicity parameters, may have a substantial impact on the outcome. Our results are quantitatively applicable to Finland, but may also be of relevance to other low-seismicity regions in Europe and elsewhere. For future work we recommend the exploration of PSHA sensitivity with focus on the host SSZ with its immediate vicinity and the b value around the site of interest.We investigate probabilistic seismic hazard analysis (PSHA) in low-seismicity regions in which epistemic uncertainties are largely due to the sparsity of data, with a focus on Finland, northern Europe. We investigate the sensitivity of site-specific PSHA outcomes to different choices of basic input parameters, starting from preexisting PSHA models of the nuclear licensees in the country, without producing a final hazard curve. The outcome shows that the parameters and models needed to estimate future seismicity rates from actual observations, in particular the b value, seismicity rates, and the largest possible magnitude, Mmax, as well as the median ground-motion prediction equation, play significant roles. The sensitivity also depends on the spectral frequency; for example, the effect of Mmax is significant especially for a low-frequency hazard at annual frequency of exceedance 10−5 but more moderate for peak ground acceleration. The delineation of seismic source zones (SSZs) remains ambiguous in regions of low seismicity. This, combined with the dominance of the host SSZ and its seismicity parameters, may have a substantial impact on the outcome. Our results are quantitatively applicable to Finland, but may also be of relevance to other low-seismicity regions in Europe and elsewhere. For future work we recommend the exploration of PSHA sensitivity with focus on the host SSZ with its immediate vicinity and the b value around the site of interest.Peer reviewe

Quantitative Comparison of Mast cells in Major Salivary Glands in Hypothyroid State

Background: This experimental study was carried out to compare the number of mast cells in major salivary glands of albino rat in hypothyroid state.Methods: An experimental study was carried out on twenty male albino rats, weighing between 130-150 grams. The rats were divided into two groups; control group (A) and an experimental group (B), with 10 animals in each group. Hypothyroid condition was modeled in albino rats of experimental group (B) by giving them 0.02% w/v Methimazole (MMI) for three weeks in drinking water. After 4-weeks animals from both the groups were euthanized with chloroform. The blood sample was taken from each rat for determination of thyroid hormone concentrations in the serum by cardiac puncture. Serum T3, T4 and TSH levels were determined by enzyme immunoassay to confirm hypothyroid state of the animal. Major salivary glands; parotid, submandibular and sublingual were dissected and removed from the body. They were fixed in Bouin’s solution. Glands were further processed for light microscopy and for histological analysis of mast cells Toluidine blue stain was used. Counting of mast cells (MCs) was performed by superimposing the ocular graticule on the salivary gland preparation.Results: Statistically significant difference was observed between the MCs of parotid gland in group A (2.25±1.34/mm2) and B (3.70+1.11/mm2), p<0.017. No significant difference was observed in the mean number of MCs in the sublingual and submandibular salivary glands with p=0.511 and p=0.187 respectively.Conclusion: In hypothyroid state, there is significant difference in the number of MCs in the parotid glands and there is no significant difference in the number of MCs of submandibular and sublingual glands

Modelling of aged reinforced concrete structures for design extension conditions (CONFIT)

The CONFIT project uses a multi-disciplinary approach to investigate the various physical and chemical degradation mechanisms and how they affect the mechanical load bearing capacity of concrete in long term operation. Reinforced concrete structures are, indeed, of safety relevance in nuclear power plants due to the containment function of the reactor building and load bearing functions of the control building and shielding functions of specific concrete structures.During the project, it was investigated how various external chemical and physical stressors affect the mechanical concrete properties as a material (Ferreira, M. and Fülöp, L., 2020) and in particular how corrosion of the reinforcement affects the load bearing capacity of a concrete structure (Calonius, et al., 2023b) and how this can be numerically simulated (Calonius, et al. 2021). For the simulation of full-scale loading scenarios on reinforced concrete structures involving physically, chemically or mechanically deteriorated concrete, specific material models for concrete were developed during the project. One of the advantages of such advanced concrete models is the ability to respond to anisotropic behaviour, which is inherent in damaged concrete (Vilppo, et al., 2021).Since the calibration of the model parameters requires measurements of anisotropy in concrete under controlled multiaxial loading, a specific method using ultrasonic wave velocity measurement was developed (Calonius et al., 2022c). This method enables the computation of the damaged stiffness matrix components from the ultrasonic pressure and shear wave velocity measurements on the concrete sample in different directions.As a result, the project has generated important findings in the domain of nuclear safety, some of which present novelty value of academic importance