Justifying the validity of safety assessment models with safety case patterns

2011 ◽  
Author(s):  
L. Sun ◽  
O. Lisagor ◽  
T. Kelly
Keyword(s):  
Safety Assessment ◽  
Safety Case

scholarly journals Science underpinning the safety case of deep geological repositories − challenges in the past and in the future and how to maintain knowledge and competence during operation

2020 ◽  
Vol 6 ◽  
pp. 24
Author(s):  
Johan Andersson
Keyword(s):  
International Cooperation ◽  
Safety Assessment ◽  
Spent Nuclear Fuel ◽  
Research Strategy ◽  
Version Control ◽  
The Past ◽  
Safety Case ◽  
Long Time ◽  
New Challenges ◽  
New Phase

Final repositories for spent nuclear fuel are approaching implementation. A prerequisite for these advancements is that it has been shown that the repository can be constructed and operated in practice in such a way that safety can be assured both during operation and over very long time scales. The success rests on decades of structured and objective-driven research and development. A key element of the research strategy has been to ensure adequate in-house competence and expertise. Also, openness and international cooperation are essential. Workable procedures for data qualification, version control as well as internal and external peer review have gained importance. When the programmes now enter a new phase of construction and operation new challenges will arise. Even if the implementing organisations would need to keep a core competence on post closure safety assessment international cooperation will be even more important on developing, sharing and managing the knowledge needed.

Offshore Safety Assessment and Safety-Based Decision-Making—The Current Status and Future Aspects

1999 ◽  
Vol 122 (2) ◽  
pp. 93-99 ◽  
Author(s):  
J. Wang ◽  
O. Kieran
Keyword(s):  
Decision Making ◽  
Safety Assessment ◽  
Safety Analysis ◽  
Current Status ◽  
Safety Critical ◽  
Critical Elements ◽  
Offshore Installations ◽  
Safety Case ◽  
The Uk ◽  
Further Development

The offshore installations (safety case) regulations were developed in the UK in 1992 and came into force in 1993 in response to the accepted findings of the Piper Alpha enquiry. Recently, “the offshore installations and wells (design and construction, etc.) regulations” (DCR 1996) were introduced to offshore safety analysis. From the earliest stages of the installation’s life cycle, operators must ensure that all safety-critical elements in both the software and system domains be assessed. Hazards can be identified and the risks associated with them can be assessed and evaluated using a number of techniques and decision-making strategies, all aimed at producing an installation with lifetime safety integrity. In this paper, following a brief review of the current status of offshore safety regulation in the UK, several offshore safety assessment frameworks are presented. These include top-down, bottom-up, probabilistic, and subjective approaches. The conditions under which each approach may be applied effectively and efficiently are discussed. Probabilistic safety-based decision-making and subjective safety-based decision-making are then studied. Two examples are used to demonstrate the decision-making approaches. Recommendations on further development in offshore safety analysis are suggested. [S0892-7219(00)00901-8]

The Safety Case for a Deep Geological Repository: More Than Just Presenting Numbers

2001 ◽  
Author(s):  
Jürg W. Schneider ◽  
Lawrence H. Johnson ◽  
Piet Zuidema ◽  
Paul A. Smith ◽  
Peter Gribi
Keyword(s):  
Waste Management ◽  
Safety Assessment ◽  
Management Programme ◽  
Deep Geological Repository ◽  
Natural Analogue ◽  
Full Spectrum ◽  
Independent Evidence ◽  
Geological Repository ◽  
Safety Case

Abstract A convincing safety case is a prerequisite for positive decisions in the stepwise process of planning and implementing a deep geological repository. In addition to evaluations of dose or risk, a safety case must provide arguments that the system and its safety functions are well understood, that the methods, models and data used in the evaluations are applicable, and have been correctly applied, and that the full spectrum of possibilities for the characteristics of the repository system and its evolution has been taken into account in defining the cases to be evaluated. This paper takes examples from the Swiss waste management programme and from natural analogue studies to illustrate how the safety functions for a repository are taken into account in a safety assessment and how independent evidence can be used to support the statement that these safety functions will operate as expected.

The Second Safety Assessment and Feasibility Interim Report (SAFIR 2 Report) on HLW Disposal in Boom Clay: Overview of the Belgian Programme

2003 ◽  
Vol 807 ◽  
Author(s):  
Robert Gens ◽  
Philippe Lalieux ◽  
Peter De Preter ◽  
Ann Dierckx ◽  
Johan Bel ◽  
...  
Keyword(s):  
Safety Assessment ◽  
State Of The Art ◽  
Technical Feasibility ◽  
Geological Disposal ◽  
Boom Clay ◽  
Safety Case ◽  
Clay Formation ◽  
Main Barrier

ABSTRACTONDRAF/NIRAS – the Belgian radioactive waste management agency – has published in 2001 the SAFIR 2 report on request of the authorities. The SAFIR 2 report is to be considered as a state-of-the art report and not as a complete safety case. This report gives an overview of the Belgian R&D program related to the geological disposal of HLW and ILW for the period 1990–2000 in the Boom Clay (reference host rock). The three main outcomes of the SAFIR 2 report on which this paper will be more specifically focusing, are the following (including results reported after 2000): long-term safety functions, confirmation of the role of the Boom Clay formation as the main barrier and identification of practical difficulties with respect to technical feasibility (repository design).

scholarly journals Overview OF14C release from irradiated zircaloys in geological disposal conditions

Radiocarbon ◽  
2018 ◽  
Vol 60 (6) ◽  
pp. 1757-1771
Author(s):  
S Necib ◽  
C Bucur ◽  
S Caes ◽  
F Cochin ◽  
B Z Cvetković ◽  
...  
Keyword(s):  
Neutron Activation ◽  
Safety Assessment ◽  
Point Of View ◽  
Alkaline Media ◽  
Primary Circuit ◽  
Surface Conditions ◽  
Carbon 14 ◽  
Safety Case ◽  
Leaching Experiments ◽  
Good Agreement

ABSTRACTCarbon-14 (radiocarbon,14C) is a long-lived radionuclide (5730 yr) of interest regarding the safety for the management of intermediate level wastes (ILW). The present study gives an overview of the release of14C from irradiated Zircaloy cladding in alkaline media.14C is found either in the alloy part of Zircaloy cladding due to the neutron activation of14N impurities by14N(n,p)14C reaction, or in the oxide layer (ZrO2) formed at the metal surface by the neutron activation of17O from UO2or (U-Pu)O2fuel and water from the primary circuit in the reactor by17O(n,α)14C reaction. Various irradiated and unirradiated Zircaloys have been studied. The total14C inventory has been determined both experimentally and by calculations. The results seem to be in good agreement. Leaching experiments were conducted in alkaline media for several time durations.14C was mainly released as carboxylic acids. Further, corrosion measurements were performed by using both hydrogen measurements and electrochemical measurements. The corrosion rate (CR) ranges from a few nm/yr to 100 nm/yr depending on the surface conditions and the method used for measurement. From a safety assessment point of view, the instant release fraction (IRF) was determined on irradiated Zircaloy-2. The results showed that the14C inventory in the oxide was significantly below the 20% commonly used in safety case assessments.

South African Safety Assessment Framework for the Pebble Bed Modular Reactor

2008 ◽  
Author(s):  
Jean Joubert ◽  
Norbert Kohtz ◽  
Ian Coe
Keyword(s):  
South African ◽  
Safety Assessment ◽  
Assessment Process ◽  
Current Status ◽  
Pebble Bed ◽  
Formal Assessment ◽  
Safety Case ◽  
Regulatory Assessment ◽  
Safety Assessments ◽  
Assessment Activities

It is planned to construct a first of a kind Pebble Bed Modular Reactor (PBMR) in South Africa. A need has been recognized to accompany the licensing process for the PBMR with independent safety assessments to ensure that the safety case submitted by the applicant complies with the licensing requirements of the NNR. At the HTR 2006 Conference, the framework and major challenges on safety assessment that the South African National Nuclear Regulator (NNR) faces in developing and applying appropriate strategies and tools were presented. This paper discusses the current status of the various NNR assessment activities and describes how this will be considered in the NNR Final Report on the PBMR Safety Case. The traditional safety assessment process has been adapted to take into account the developmental nature of the project. By performing safety assessments, the designer and applicant must ensure that the design as proposed for construction and as-built meets the safety requirements defined by the regulatory framework. The regulator performs independent safety assessments, including independent analyses in areas deemed safety significant and potentially safety significant. The developmental nature of the project also led to the identification of a series of regulatory assessment activities preceding the formal assessment of the safety case. Besides an assessment of the resolution of Key Licensing Issues which have been defined in an early stage of the project and are discussed in /1/, these activities comprise the participation in an SAR Early Intervention Process, the execution of a regulatory HAZOP and the development of a regulatory assessment specification for the formal assessment of the safety case. This paper briefly describes these activities and their current status. During the last two years, significant progress was made with the development or adjustment of tools for the independent analysis by the regulator of the steady state core design, of the transient neutronic/thermal hydraulic behaviour of the reactor, of fission product release from the fuel elements, and of activation of fuel matrix and graphite impurities.

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