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1

Development of a Library Based Tool for Screening External Hazards and Hazard Combinations

Röwekamp M., Sperbeck S., Türschmann M.

Journal of Polish Safety and Reliability Association

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2017

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Vol. 8, No. 1

105--110

EN

For a meaningful and efficient probabilistic risk analysis of external hazards and event combinations involving such hazards those hazards with significant risk potential need to be identified and considered for detailed anal-yses. Such a site and plant specific screening approach for external and internal hazards based on a hazards library covering all types of hazards is under development at GRS. The paper provides insights on the approach and first examples of application.

2

Loss of offsite power caused by tornado in Surry NPP : a case study

Borysiewicz M., Kaszko A., Kowal K., Potempski S.

Journal of Polish Safety and Reliability Association

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2015

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Vol. 6, No. 3

25--30

EN

The aim of this work was to perform the real case study for the US Surry Nuclear Power Plant which was touched down by tornado in 2011 causing the electrical switch yard destruction and loss of offsite power. Probabilistic methods have been applied to assess the reliability of the reactor shutdown and effective heat removal after this accident. The reactor protection system and auxiliary feedwater system were thoroughly analysed in the context of their safety features designed to prevent the reactor core damage. The emergency power system reliability has been also considered due to the fact that some components of the safety systems are electrically operated. Moreover, time-dependent analysis has been performed in order to address the level of damages after an extreme external event like tornado. Depending on the severity of such events the time required to restore the electrical grid may be significantly different and longer than 24 hours. The reliability and requirements for safety systems are changing with time and these changes have been taken into account as well.

3

Ageing PSA as a support for effective ageing management

Berg H. P., Volkanovski A.

Journal of Polish Safety and Reliability Association

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2014

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Vol. 5, No. 2

1--10

EN

Because of the growing operational age of nuclear power plants, the ageing management of structures, systems and components used in these plants is gaining an important role. Technical systems are subject to timedependent and operationally caused ageing phenomena with modifications of originally given characteristics and, thus, of relevance in terms of safety. Especially physical ageing is of importance. Therefore, a comprehensive ageing management is required. In the context of an integrated safety management it has to be shown how to integrate the safety related issues of ageing into probabilistic safety assessment (PSA). In particular the question is to be answered whether the effort for the execution of an ageing PSA is justified, in particular if the safety significant effects of ageing can be identified and quantitatively estimated. Method for prioritization of the components in the nuclear power plant considering implication of their ageing on safety of the nuclear power plant is presented. On the basis of an actual report on ageing management in German nuclear power plants and a literature survey, this paper tries to estimate the necessity and value for the introduction of an ageing PSA in Germany.

4

An integrated risk informed decision making in the nuclear industry

Borysiewicz M., Kowal K., Prusiński P. A., Dąbrowski M.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2013

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nr 2

22--34

EN

The regulatory body, established to ensure safety of nuclear facilities, is expected to make right decisions and provide appropriate regulations for the nuclear industry. The traditional manner of its activity has been based on a deterministic approach to safety analyses. However, increased maturity of Probabilistic Safety Assessment (PSA) makes it complementary to deterministic studies. The new IAEA concept, described in this article, is to apply an integrated approach by combining both deterministic and probabilistic insights with other requirements affecting the decision making process.

PL

Organ regulacyjny, powołany w celu zapewnienia bezpieczeństwa jądrowego, jest odpowiedzialny za podejmowanie decyzji i wprowadzanie rozporządzeń dla przemysłu jądrowego. Tradycyjny sposób jego funkcjonowania opiera się na deterministycznym podejściu do analiz bezpieczeństwa. Rozwój analiz probabilistycznych (PSA) sprawia jednak, iż są one traktowane jako podejście komplementarne. Nowa koncepcja IAEA, opisana w tym artykule, polega na zintegrowanym podejściu, uwzględniającym analizy deterministyczne, probabilistyczne i inne aspekty procesu decyzyjnego.

5

Assessing the risk of the transport of radioactive material

Berg H. P.

Journal of Polish Safety and Reliability Association

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2012

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Vol. 3, No. 1

89--100

EN

Transport of dangerous goods are always under critical observation of the public, in particular in case of transport of spent fuel or radioactive waste. In both cases transports are often crossing borders of countries, e.g., waste resulting from reprocessing of spent fuel. The transports could take place by ships, trucks, rails and airplanes and these options and the resulting risks are compared. Transport risk includes health and safety risks that arise from the exposures to workers and members of the public to radiation from shipments Moreover, it is shown that the more modern approach of risk-informed decision making elaborated for application to nuclear installations can also be applied to assess the risk of the transport of radioactive material.

6

Assessing external explosions and their probabilities

Berg H. P., Hauschild J.

Journal of Polish Safety and Reliability Association

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2011

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Vol. 2, No. 1

23--32

EN

External hazards such as explosions can be safety significant contributors to the risk in case of operation of industrial plants. The procedure to assess external hazard explosion pressure waves within probabilistic safety assessment starts with a screening procedure in order to determine scope and content of the assessment. The second step is to choose an appropriate approach in case that a full scope analysis has to be performed. Several methods can be applied to evaluate the probability of occurrence of an external explosion event. The presented results indicate that the probability of occurrence of external explosion pressure waves can be successfully assessed by means of the Monte Carlo simulation, in particular in difficult site-specific conditions.

7

Monte Carlo simulation-based reliability model for the PSA of a radioactive waste repository

Cadini F., Avram D., Zio E., Luce A., Taglioni A.

Journal of Polish Safety and Reliability Association

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2010

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Vol. 1, No. 1

43--50

EN

Disposal facilities for radioactive wastes comprise a series of engineered barriers whose purpose is to contain the radionuclides until their radiation hazard has decreased to acceptable levels. In this regard, it is required that the long-term functionality of the system of barriers be evaluated by a quantitative risk analysis procedure, also called performance assessment. In this paper, a Monte Carlo simulation-based reliability model is propounded for the preliminary analysis of the safety performance of a radioactive waste repository, accounting also for barrier degradation processes. The model strengths are: simplicity, chich allows ease of computation, and flexibility, which allows modification to account for various physical aspects and inter-comparison of their effects. An application to a case study of literature is presented to validate the approach and demonstrate its flexibility.

8

Aircraft crash onto a nuclear power plant : screening procedure and approach for a probabilistic analysis

Berg H.-P.

Journal of Polish Safety and Reliability Association

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2010

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Vol. 1, No. 1

27--34

EN

International experience has shown that external hazards (e.g. aircraft crash, flooding) can be safety significant contributors to the risk in case of nuclear power plants` operation. This is due to the fact that such hazards have the potential to reduce simultaneously the level of redundancy by damaging redundant systems or their supporting systems. In this paper, the procedure for the external hazard aircraft crash is described In more detail, starting with the screening procedure in order to determine scope and content of the assessment and the approach for those cases where a full scope analysis has to be performed. The consideration regarding this hazard does as not cover an intended aircraft crash.

9

Proposal for estimating leak and break frequencies of piping systems in probabilistic safety assessment

Berg H.-P., Gersinska R., Sievers J.

Journal of Polish Safety and Reliability Association

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2009

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Vol. 1

33--42

EN

The estimation of leak and break frequencies in piping systems is part of the probabilistic safety assessment of technical plants. In this paper, the statistical method based on the evaluation of the German operational experience for piping systems with different diameters is described because an earlier estimation has been updated and extended introducing new methodical aspects and data. Major point is the inclusion of structure reliability models based on fracture mechanics calculation procedures. As an example of application the statistical estimation method for leak and break frequencies of piping systems with a nominal diameter of 50 mm (the volume control system of a German pressurized water reactor) was updated. Moreover, the evaluation of the operational experience was extended to 341 years with respect to cracks, leaks and breaks in the volume control system of German pressurized water reactors (PWR). Using the actual data base, new calculations of leak and break frequencies have been performed and the results have been compared with the previous values.

10

An approach to estimate radioactive release frequency from Ignalina RBMK-1500 reactor in Lithuania.

Kopustinskas V., Urbonavicius E., Kaliatka A., Rimkevcius S., Uspuras E., Bagdonas A., Hellstroem P., Johanson G.

Zagadnienia Eksploatacji Maszyn

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2007

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Vol. 42, nr 1

183-199

EN

The paper presents an approach to estimate the radioactive release frequency from Ignalina nuclear power plant in Lithuania. The study was completed within the frame of Barselina project, initiated in 1991 as a multilateral co-operation between Lithuania, Russia and Sweden with the long-range objective to establish common perspectives and unified bases for assessment of severe accident risks and needs for remedial measures for the RBMK type reactors. The paper presents the study results and discusses a number of future development efforts.

PL

W artykule przedstawiono podejście do zagadnienia estymacji częstości uwolnień substancji radioaktywnych z elektrowni jądrowej Ignalina na Litwie. Prace zostały wykonane w ramach projektu Barselina, zapoczątkowanego w 1991 roku jako wielostronna współpraca między Litwą, Rosją i Szwecją, mającego na celu ustanowienie współczesnych perspektyw i zunifikowanych baz do oceny ryzyka poważnych awarii oraz potrzeb dotyczących środków zaradczych dla reaktorów typu RBMK. W artykule przedstawiono wyniki dotychczasowych badań oraz omówiono przyszłe działania w tym zakresie.

11

Methods for the treatment of common cause failures in redundant systems

Berg H. P., Görtz R., Kesten J.

Journal of Polish Safety and Reliability Association

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2007

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Vol. 1

1--8

EN

Dependent failures are extremely important in reliability analysis and must be given adequate treatment so as to minimize gross underestimation of reliability. German regulatory guidance documents for PSA stipulate that model parameters used for calculating frequencies should be derived from operating experience in a transparent manner. Progress has been made with the process oriented simulation (POS) model for common cause failure (CCF) quantification. A number of applications are presented for which results obtained from established CCF models are available, focusing on cases with high degree of redundancy and small numbers of observed events.

12

Improving reactor safety systems using component redundancy allocation technique

Habib A., Ashry H., Shokr A., Dakhly A.

Nukleonika

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2005

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Vol. 50, nr 3

105-112

EN

This paper addresses the improvements to the reliability of the safety systems of nuclear reactors using redundancy allocation technique. The study has been carried out using the Probabilistic Safety Assessment (PSA). PSA involves, among others, the use of fault and event tree tools in the evaluation of the safety system failure probabilities and the quantification of annual occurrence probability of the accidental conditions postulated in the design of the nuclear reactors. The PSA has been presented and discussed. The Egypt Second Research Reactor, ETRR-2, has been used as a case study. The failure probability of the already existing safety systems has been reviewed. The effect of the allocation of more redundant components to the existing safety systems on the failure probability of the systems has been evaluated. The event trees for two selected initiating events, from those events postulated in the ETRR-2 design, have been studied considering the allocation of more redundant components to the safety systems. The result of the study showed that further improvement could be introduced to the reliability of the Confinement Ventilation System (CVS).

13

Development of a Bayesian belief network for a boiling water reactor during fault conditions

Frid W., Knochenhauer M., Bednarski M.

Computer Assisted Mechanics and Engineering Sciences

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2005

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Vol. 12, No. 2-3

133-145

EN

This paper describes briefly the development and verification of a probabilistic system for the rapid diagnosis of plant status and radioactive releases during postulated severe accidents in a Boiling Water Reactor nuclear power plant. The probabilistic approach uses Bayesian belief network methodology, and was developed in the STERPS project in the European Union 5-th Euroatom Framework program.

14

Some remarks on the application of BFR-type models to common cause failures.

Berg H.P., Goertz R., Schimetschka E.

Zagadnienia Eksploatacji Maszyn

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2003

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Vol. 38, nr 4

187-196

EN

The results of a number of probabilistic safety assessments for German NPPs are presented which have shown the importance of common cause failures for the overall safety level of the plant. Binomial failure rate models and a process oriented simulation model for estimating CFF frequencies are described and their relative merits discussed.

PL

Przedstawione zostały wyniki licznych oszacowań bezpieczeństwa niemieckich siłowni nuklearnych. Pokazane zostało znaczenie uszkodzeń o wspólnej przyczynie (CCF) dla ogólnego bezpieczeństwa siłowni. Opisano binominalne modele intensywności uszkodzeń oraz model zoientowanej na proces symulacji estymującej częstotliwości CCF. Przedyskutowane zostały relatywne zalety tych modeli.