Features of high-temperature diffusion in concrete at the 4th block of the Chernobyl NPP

The element distribution and structural-phase changes in core samples taken from concrete wall in one of the rooms of the Chernobyl Nuclear Power Plant subjected to penetration of lava-like fuel-containing mass were studied by γ-ray activation and crystal-optical methods and IR spectrometry. High-temperature diffusion processes in concrete that occurred in the course of the Chernobyl accident (1986) were simulated using the developed numerical model describing concrete as a porous multiphase system occurring on the local level in the thermodynamic equilibrium with the matrix voids filled with water and gas. Comparison of theoretical results with profiles of the content of particular elements and with characteristics of newly formed minerals shows that the high-temperature fluid cloud saturated with aggressive reduction gases played the decisive role in the processes occurring during the first stage of the accident.     

The alcohol-related accident risk in Germany: procedure, methods and results

This paper presents the first reliable estimation of the alcohol-related accident risk in Germany by comparing a representative sample of accidents to a representative sample of trips not leading to a crash. The information about the trips was taken from the German Roadside Survey 1992-1994 (n=9087) conducted in Unterfranken, part of Bavaria. These data were weighted according to a representative study of driving in Germany (KONTIV 89). The accident study comprises a representative sample of accidents in Unterfranken in 1993 (n=1968). Relating accident risk to BAC, the global risk function indicates an exponential increase of accident risk for BACs above 0.05%. Controlling for correlating factors leads to an overall lower estimation with, however, the same structure, indicating that alcohol is consumed by drivers in circumstances which further increase the risk introduced by alcohol. Analyzing the attributable risk (AR) shows that about 12% of all accidents are attributable to alcohol. Over 96% of these happen with BACs of 0.05% and above. Thus, measures aimed at reducing the alcohol-related accident risk must focus on larger BACs, especially of 0.08% and above.     

The impact of traffic violations on the estimated cost of traffic accidents with victims

We analyse accidents with victims and calculate the influence of traffic violations on the probability of having a serious or fatal accident, compared to a slight accident. Traffic violations related to speed limitations, administrative infringements or faults related to the driver are considered. Data were obtained from all available reports on accidents with victims that occurred in Spain from 2003 to 2005. A multinomial logistic regression model is specified to find the probability that an accident with victims is slight, serious or fatal, given the presence/absence of thirty different types of traffic violations. The average cost per victim and the average number of victims per accident are then used to find the estimated cost of an accident with victims, given the information on the traffic violations incurred. This demonstrates which combinations of traffic violations lead to higher estimated average costs, compared to cases in which no traffic violation occurred. We conclude with some recommendations on the severity of penalties, and suggest that regulators penalize the occurrences of some specific combinations of traffic violations more rigorously.     

A combined M5P tree and hazard-based duration model for predicting urban freeway traffic accident durations

The duration of freeway traffic accidents duration is an important factor, which affects traffic congestion, environmental pollution, and secondary accidents. Among previous studies, the M5P algorithm has been shown to be an effective tool for predicting incident duration. M5P builds a tree-based model, like the traditional classification and regression tree (CART) method, but with multiple linear regression models as its leaves. The problem with M5P for accident duration prediction, however, is that whereas linear regression assumes that the conditional distribution of accident durations is normally distributed, the distribution for a “time-to-an-event” is almost certainly nonsymmetrical. A hazard-based duration model (HBDM) is a better choice for this kind of a “time-to-event” modeling scenario, and given this, HBDMs have been previously applied to analyze and predict traffic accidents duration. Previous research, however, has not yet applied HBDMs for accident duration prediction, in association with clustering or classification of the dataset to minimize data heterogeneity. The current paper proposes a novel approach for accident duration prediction, which improves on the original M5P tree algorithm through the construction of a M5P-HBDM model, in which the leaves of the M5P tree model are HBDMs instead of linear regression models. Such a model offers the advantage of minimizing data heterogeneity through dataset classification, and avoids the need for the incorrect assumption of normality for traffic accident durations. The proposed model was then tested on two freeway accident datasets. For each dataset, the first 500 records were used to train the following three models: (1) an M5P tree; (2) a HBDM; and (3) the proposed M5P-HBDM, and the remainder of data were used for testing. The results show that the proposed M5P-HBDM managed to identify more significant and meaningful variables than either M5P or HBDMs. Moreover, the M5P-HBDM had the lowest overall mean absolute percentage error (MAPE).     

Catastrophe modeling of the accident process: evaluation of an accident reduction program using the occupational hazards survey

The report details a catastrophe theory model of the accident process with empirical validation. According to the cusp model, two distinct levels of risk can be observed for a distribution of group accident rates, one at 0.0 Occupational Safety and Health Association (OSHA)-reportable accidents per 100 person-years of exposure and one at 11.5. Changes within or between the two levels are determined by two control parameters: environmental hazard (asymmetry) and operator load (bifurcation). The sample consisted of 68 work groups from 8 Milwaukee-Chicago area sheet metal mills and foundries who completed the Occupational Hazards Survey (OHS). The OHS contributed six bifurcation variables (safety management, life stress, physical stress anxiety, beliefs about accident control, and experience) and two asymmetry variables (environmental hazards and danger). All organizations received an interpretive report of their survey responses with recommendations for accident control, and had held their reports for two to nine months at the time the follow-up accident rate data were collected. There were two additional bifurcation variables: months holding report and group size. Regression analysis determined that the cusp model (R2 = .42) was more than twice as accurate as the best log-linear or linear alternative. Accidents were successfully controlled by safety managers' attention to recommendations produced by the OHS analysis. Catastrophe theory provided some novel insights regarding the linkage between predictor variables and actual behavior. Research has shown that a substantial percentage of occupational accidents are the result of human error. In an effort to explain and predict such errors in a systematic manner, an accident process model based on the cusp catastrophe is developed and tested. The model offers several unique and useful properties: (1) It proposes that changes in accident rates for work groups are the result of a nonlinear dynamic process. (2) The distribution of accident rates is bimodal, with one model near zero and the other at some higher level. (3) Changes in accident rates are predicted from four sources: (i) ambient danger and hazard levels, (ii) variables that impact upon human performance capability, (iii) initial accident rates, and (iv) the mathematical function that interrelates those variables. (4) The mathematical model has inherent properties that allow for causal inference. Environmental and human performance factors can be operationalized as sets of more specific variables. In this application. The Occupational Hazards Survey was used to gather data from mill and foundry workers pertaining to hazards and dangers, adequacy of safety management, stress, anxiety, and beliefs about accident control.(ABSTRACT TRUNCATED AT 400 WORDS)     

Analysis for Yangmingtan Bridge collapse

In recent years, more than thirty bridge accidents have occurred in China, but only few accidents were tracked and most accident investigation reports were not open to the public. The Yangmingtan Bridge collapse accident occurred on 24 August, 2012 in Harbin City, which caused three fatalities and five injuries. This accident has evoked wide concern from the public and media, but no official report provided any conclusion on the cause of the accident until now, while no related research was ever undertaken either. NVivo is a qualitative data analysis package which helps researchers to organize and analyze complex non numerical or unstructured data. Because of the lack of data in the official report, this research collected both texts and multimedia information from the web, newspaper and videos to identify potential root causes of the accident. This research first organized all information with the aid of NVivo 8.0 software. Then Rasmussen’s accident causation model was adopted for use as the frame nodes for the case study. Based on the software, this research analyzed the system wide failures and actions involved in the accident and identified the multi-levels of failure modes which included government, regulatory agency, company, management, staff, and the physical accident sequence.     

External doses in the environment from the Tokai-mura criticality accident

On 30 September 1999, a criticality accident occurred at a uranium processing plant operated by JCO in Tokai-mura, Japan and the criticality remained for about 20 h. Almost all doses to the neighbouring residents were brought by neutrons and gamma rays emitted from the facility rather than fission products released to the environment. External doses in the environment were evaluated using radiation monitoring data and radiation transport calculation. A pattern of the dose rate evolution was modelled based on the records of gamma ray monitors in the JCO facilities. Relations between the ambient dose equivalent rates of neutrons/gamma rays and the distance from the facility were determined from the monitoring data obtained around the accident site. Conversion from the ambient dose equivalent to the effective dose equivalent was made assuming the energy spectra calculated by the radiation transport code, ANISN. It was estimated that the people who stayed outside the 350 m zone would receive doses of less than 1 mSv.     

Bayesian-network-based safety risk assessment for steel construction projects

There are four primary accident types at steel building construction (SC) projects: falls (tumbles), object falls, object collapse, and electrocution. Several systematic safety risk assessment approaches, such as fault tree analysis (FTA) and failure mode and effect criticality analysis (FMECA), have been used to evaluate safety risks at SC projects. However, these traditional methods ineffectively address dependencies among safety factors at various levels that fail to provide early warnings to prevent occupational accidents. To overcome the limitations of traditional approaches, this study addresses the development of a safety risk-assessment model for SC projects by establishing the Bayesian networks (BN) based on fault tree (FT) transformation. The BN-based safety risk-assessment model was validated against the safety inspection records of six SC building projects and nine projects in which site accidents occurred. The ranks of posterior probabilities from the BN model were highly consistent with the accidents that occurred at each project site. The model accurately provides site safety-management abilities by calculating the probabilities of safety risks and further analyzing the causes of accidents based on their relationships in BNs. In practice, based on the analysis of accident risks and significant safety factors, proper preventive safety management strategies can be established to reduce the occurrence of accidents on SC sites.     

An estimate of the effect of FMVSS 301—fuel system integrity

Federal Motor Safety Standard No. 301—Fuel System Integrity—was first promulgated, effective 1 January 1968. Its purpose was to reduce the fatalities, injuries and damage caused by fires occurring in automobile crashes. It was subsequently strengthened (1 September 1975 and again 1 September 1976) and extended to all four wheel vehicles of Gross Vehicle Weight less than 10,000 pounds (1 September 1976). This paper uses existing police accident and fire department data from a total of 10 states to estimate the effects of FMVSS 301 on the passenger car crash population. Only very limited information on the rates of fuel spillage were found, so the paper concentrates on the rate of fires in crashes involving passenger cars. Some information on fatalities from the Fatal Accident Reporting System (FARS) is also used. Post-crash passenger car fires are rare. Reported rates ranged from less than one per thousand crashes up to nearly five per thousand crashes. Rates averaged about two fires per thousand police reported crashes or about three fires per thousand towaway crashes. Fatalities are also quite rare. In 1976, 814 persons were killed in 683 vehicles that caught fire after a crash. In 1977, 982 persons died in 858 such vehicles. Fire department data proved only of supplemental use, because a car fire could not be identified with a crash. Police accident data showed smaller post-crash fire rates with newer model year cars. While this is consistent with a beneficial effect of FMVSS 301, it could also be caused by an increasing likelihood of fire in a crash for older cars. A linear trend in age for ear fire rates was statistically significant only in the Illinois data. Combining the data from 6 states showed a 16% reduction in post-crash passenger car fire rates coincident with the first promulgation of the FMVSS 301 in 1968. An additional 14% reduction occurred coincidently with the later versions starting with the 1976 model year. A total reduction of 25% was estimated comparing pre-standard models with the current standard. These reductions were all statistically significant. While it was not possible to eliminate the possibility that aging contributed to the observed reductions, or that other factors could have influenced these reductions, it seems reasonable to conclude that some of the benefit resulted from the standard.     

Development of a Skin Permeation cell to Simulate Clinical Study of Iontophoretic Transdermal Delivery

A new single-compartment iontophoretic skin permeation cell was developed to simulate the clinical application of iontophoretic devices. The stability and permeation kinetics of LHRH, the model peptide, were investigated in this new permeation cell (cell design A) using two analytical methods and compared with a commonly used skin permeation cell (cell design B). A polyacrylamide-based hydrogel device was fabricated as the drug reservoir for the iontophoretic transdermal delivery of LHRH. The skin permeation profiles of LHRH were found identical for both permeation cells when assayed by radioactivity measurement. However, cell design A gave a skin permeation profile that was substantially higher than that obtained in cell design B when assayed by HPLC. This is because the electrochemical degradation of LHRH occurred in the receptor compartment of the Valia-Chien permeation cell (cell design B). This degradation could be overcome by using the new single-compartment iontophoretic permeation cell.     

Bicycle-related head injury: a study of 86 cases

Within the framework of a bicycle helmet research program, we have set up a database of bicycle accident victims, containing both accident and clinical data. The database consists of a consecutive series of 86 victims of bicycle accidents who underwent a neurosurgical intervention in our hospital between 1990 and 2000. Data were obtained from police files, medical records, computed tomography head scans and a patient questionnaire. In only three victims, the wearing of a helmet was documented. In this study, the head injuries are analysed and the relation between the different types of head injuries and outcome is assessed. Forty-four accidents were collisions with a motor vehicle and 42 accidents were falls. Most impacts occurred at the side (57%) or at the front (27%) of the head. The most frequent injuries were skull fractures (86%) and cerebral contusions (73%). Age was negatively correlated with outcome (P = 0.0002 ) and positively correlated with the number (P = 0.00002) and volume (P = 0.00005) of contusions and the presence of subdural haematomas (P = 0.000001). The injuries with the strongest negative effect on outcome were: subarachnoid haemorrhage (P = 0.000001), multiple (P = 0.000005) or large ( P 0.0007) contusions, subdural haematoma (P = 0.001) and brain swelling (P = 0.002). A significant coexistence of these four injuries was found. We hypothesise that in many patients the contusions may have been the primary injuries of this complex and should therefore be considered as a main injury determining outcome in this study. We believe that such findings may support a rational approach to optimising pedal cyclist head protection.     

乘用车前挡风玻璃角度对行人头部/颅脑损伤影响研究

头部/颅脑损伤在车辆与行人碰撞事故中频繁发生,而行人头部与挡风玻璃的碰撞是导致头部损伤的主要原因。旨在采用数值模拟方法研究乘用车挡风玻璃倾斜角度对行人头部/颅脑损伤的影响。采用TNO多刚体行人模型和THUMS4.0头颈部有限元模型耦合得到新的行人碰撞数值模型,并结合已有的多刚体乘用车模型,借助真实的行人碰撞交通事故案例对该耦合模型进行基于人车动力学响应的有效性验证。在此基础上,构建人车碰撞模型矩阵,其中挡风玻璃角度的变化范围设定为24°~50°(间隔为2°),车辆速度设置为45 km/h,行人与车辆碰撞位置时分别处于车辆前保险杠前端1/2和1/3处。分析结果表明,该耦合模型可以较准确地再现事故中的行人动力学响应;行人碰撞保险杠前端中间(即1/2处)位置时的头部损伤较1/3处更严重;头部损伤在本文所分析的变化范围内随挡风玻璃角度的增加呈先减小后增加的变化趋势,且当挡风玻璃角度位于32°~34°左右时损伤风险较低。     

Remains of 137Cs contamination in the city of Goiânia, Brazil

The results of measurements, performed in 1999, of the remaining 137Cs contamination in some of the sites where fragments of a radioactive source of a teletherapy unit had been manipulated in 1987 are presented. This episode occurred in the city of Goiania, during Brazil's worst radiological accident ever reported. Using the technique of gamma ray spectrometry, analyses of both surface and profile soil and vegetable samples were made. High values of 137Cs activity per unit mass were found in soil layers at depths between 10 and 40cm from the surface. Some values exceeded by up to eight times the action level of 22.5 kBq x kg(-1) proposed by the Brazilian National Nuclear Energy Commission (CNEN) during the decontamination process at the time of the accident, for the first year after the accident. Absorbed dose rates at 1 m above the ground were calculated from the data of 137Cs concentration in the soil and compared with those obtained from in situ gamma ray spectrometry and from thermoluminescence dosimetry.     

Systems thinking,the Swiss Cheese Model and accident analysis: A comparative systemic analysis of the Grayrigg train derailment using the ATSB,AcciMap and STAMP models

The Swiss Cheese Model (SCM) is the most popular accident causation model and is widely used throughout various industries. A debate exists in the research literature over whether the SCM remains a viable tool for accident analysis. Critics of the model suggest that it provides a sequential, oversimplified view of accidents. Conversely, proponents suggest that it embodies the concepts of systems theory, as per the contemporary systemic analysis techniques. The aim of this paper was to consider whether the SCM can provide a systems thinking approach and remain a viable option for accident analysis. To achieve this, the train derailment at Grayrigg was analysed with an SCM-based model (the ATSB accident investigation model) and two systemic accident analysis methods (AcciMap and STAMP). The analysis outputs and usage of the techniques were compared. The findings of the study showed that each model applied the systems thinking approach. However, the ATSB model and AcciMap graphically presented their findings in a more succinct manner, whereas STAMP more clearly embodied the concepts of systems theory. The study suggests that, whilst the selection of an analysis method is subject to trade-offs that practitioners and researchers must make, the SCM remains a viable model for accident analysis.     

Buckling failure analysis of all-terrain crane telescopic boom section

In this research work, a nonlinear structure analysis by the finite element analysis (FEA) was carried out to investigate the failure reason of an all-terrain crane telescopic boom. An overall simplified model consisting of telescopic boom and luffing jib was established by beam element, and analyzed using geometric nonlinear static method. A local detailed model consisting of the 4th and 5th telescopic boom section (TBS) was established by shell and solid element, and analyzed using geometric nonlinear and contact nonlinear static method. The result of the overall simplified model FEA indicated that the boom strength met the design criteria, and the 5th TBS of local detailed model occurred stress wrinkle.Structure experiment was designed based on the boom load characteristics in accident and analyzed using nonlinear static method and explicit dynamic method; the connection of load, boom buckling failure and stress wrinkle was studied. The result indicated that the accident was caused by elastic buckling. When the telescopic boom stress state changed from continuous state to wrinkle state, the buckling occurred. So the critical buckling state characteristic was stress wrinkle.     

Analysing an accident related to orphan sources including dose assessment

This paper discusses an accident, which occurred in one of the radiation application centres in Iran, follow-up investigations as well as lessons learnt. In January 2004 the Regulatory Authority was informed through a university radiation protection officer of an accident regarding orphan sources. Investigations revealed that one Am-Be and three (137)Cs sources in the container were subject to extensive heat due to burning of the container and melting of the paraffin content of the container; consequently, sources were stuck to the side wall of the container, but they were still undamaged and no radioactive leaking had occurred. Further investigations showed that the container had been given to the above mentioned centre a long time before by a foreign well-logging company without notifying the Regulatory Authority. Follow-up measurements and assessments indicated that the collective effective dose due to the accident is unlikely to be more than 21 mSv; consequently, no severe deterministic effect to individuals was expected. The findings showed that the main reasons for the accident were as follows: (1) violation of obligation under radiation protection regulations by the owner of the sources; (2) leaving the sources in an improper storage condition; (3) unauthorised access to the radiation sources at the owner centre; and (4) lack of an integrated national registration system in the Regulatory Authority.     

Reconstruction of radiation situation at Chernobyl NPP service area on the basis of γ-ray spectrometric analysis of soil samples and published data

Reconstruction of the radiation situation in areas subjected to nuclear accidents was done with an example of the Chernobyl accident (1986) on the basis of the radionuclidic composition of soil samples. The radionuclidic composition of γ-emitters was determined 19 years after the accident in a pulverescent sandstone sample collected in July 1986 at a distance of 1.5 km from the 4th block. Using reference data and data from original papers, reconstruction of the radionuclidic composition of the sample is done on the first ten days after the accident, and possible variations of the γ-radiation dose rate were determined within the framework of the thin film model. Based on the results obtained, variations of the absorbed dose of γ-radiation in 10 days are estimated, which is necessary for making urgent decisions in the initial period after the accident. The results are well consistent with the published data on the dose rates, validating the decision on evacuation of the people from Pripyat town and from the 30-km exclusion zone.     

Contribution of different foodstuffs to the internal exposure of rural inhabitants in Russia after the Chernobyl accident

In a large village, Veprin of the Bryansk region of Russia contaminated with radionuclides as a result of the Chernobyl accident, 137Cs concentration in food products of agricultural produce and natural origin was regularly measured, local inhabitants were polled on the composition of their diet, and the 137Cs content in their bodies was measured at the same time. These results were used as the basis for calculation of annual effective doses of internal exposure to inhabitants and for reconstruction of the dose during the entire period after the accident (1986-1996). The efficiency of countermeasures performed for reduction of the internal dose was assessed. The internal dose in inhabitants during the 10 years after the accident was shown to be reduced by countermeasures by a factor of 2, namely down to 35 mSv instead of the expected 70 mSv. The dose of external gamma radiation during the same time period is close to the obtained dose of internal exposure. The presence of peat and water-meadow soils in the vicinity of this village that are characterised by high transfer factors for radionuclides from soil to vegetation causes a high contribution of internal exposure to the total dose of population exposure. The contribution of natural products to the internal dose increased from 6% in 1987 increased to 25% in 1996. The individual content of 137Cs in the body of inhabitants reliably correlates with consumption of milk in the initial period after the accident and with consumption of forest mushrooms in the subsequent period.     

Logistic regression analysis of pedestrian casualty risk in passenger vehicle collisions in China

A large number of pedestrian fatalities were reported in China since the 1990s, however the exposure of pedestrians in public traffic has never been measured quantitatively using in-depth accident data. This study aimed to investigate the association between the impact speed and risk of pedestrian casualties in passenger vehicle collisions based on real-world accident cases in China. The cases were selected from a database of in-depth investigation of vehicle accidents in Changsha-IVAC. The sampling criteria were defined as (1) the accident was a frontal impact that occurred between 2003 and 2009; (2) the pedestrian age was above 14; (3) the injury according to the Abbreviated Injury Scale (AIS) was 1+; (4) the accident involved passenger cars, SUVs, or MPVs; and (5) the vehicle impact speed can be determined. The selected IVAC data set, which included 104 pedestrian accident cases, was weighted based on the national traffic accident data. The logistical regression models of the risks for pedestrian fatalities and AIS 3+ injuries were developed in terms of vehicle impact speed using the unweighted and weighted data sets. A multiple logistic regression model on the risk of pedestrian AIS 3+ injury was developed considering the age and impact speed as two variables. It was found that the risk of pedestrian fatality is 26% at 50 km/h, 50% at 58 km/h, and 82% at 70 km/h. At an impact speed of 80 km/h, the pedestrian rarely survives. The weighted risk curves indicated that the risks of pedestrian fatality and injury in China were higher than that in other high-income countries, whereas the risks of pedestrian casualty was lower than in these countries 30 years ago. The findings could have a contribution to better understanding of the exposures of pedestrians in urban traffic in China, and provide background knowledge for the development of strategies for pedestrian protection.     

Cases of post-accident contamination with iodine 131I, registered in the Institute of Atomic Energy POLATOM in Swierk, Poland

The paper presents four cases of post-accidental contamination with iodine (131)I, registered in the Radiation Protection Measurements Laboratory (LPD) of the Institute of Atomic Energy POLATOM. Two cases were registered during routine monitoring of internal exposures carried out at LPD laboratory, one case corresponds to in vivo measurements performed at LPD after Chernobyl accident in 1986, and the last case is associated with an emergency situation after an accident occurred in a Polish hospital. In all cases, thyroid measurements were performed; for hospital employees whole-body and urine measurements were also carried out.