Mutant generation for embedded systems using kernel-based software and hardware fault simulation

Traditionally, mutation testing is used as test set generation and/or test evaluation criteria once it is considered a good fault model. This paper uses mutation testing for evaluating an automated static analyzer. Since static analyzers, in general, report a substantial number of false positive warnings, the intention of this study is to define a prioritization approach of static warnings based on their correspondence with mutations. On the other hand, knowing that Mutation Test has a high application cost, another possibility is to try to identify mutations of some specific mutation operators, which an automatic static analyzer is not adequate to detect. Therefore, this information can be used to prioritize the order of incrementally applying mutation operators considering, firstly, those with no correspondence with static warnings. In both cases, contributing to the establishment of incremental strategies on using automatic static analysis or mutation testing or even a combination of them. We used mutation operators as a fault model to evaluate the direct correspondence between mutations and static warnings. The main advantage of using mutation operators is that they generate a large number of programs containing faults of different types, which can be used to decide the ones most probable to be detected by static analyzers. We provide evidences on the correspondence between mutations and some types of static warnings. The results obtained for a set of 19 open-source programs indicate that: 1) static warnings may be prioritized based on their correspondence level with mutations; 2) specific set of mutation operators and their mutations may be prioritized based on their correspondence level with warnings. It is possible to provide an incremental testing strategy aiming at reducing the cost of both static analysis and mutation testing using the correspondence information between these activities/artifacts.

Stability and steady state analysis of control and safety systems of Nuclear Power Plants

Mutation testing is a well known technique for estimating and improving the quality of test suites. Given a test suite T for a system S, mutation testing systematically creates mutants of S and executes T to measure how many mutants T detects. If T does not detect some (non-equivalent) mutants, T can be improved by adding test cases that detect those mutants. Mutants are created by applying mutation operators. Mutation operators are important because they define the characteristics of the system that are tested as well as the characteristics that are improved in the test suite. While mutation operators are well defined for a number of programming paradigms such as sequential or multi-threaded, to the best of our knowledge, mutation operators have not been defined for the actor programming model. In this paper, we define and classify mutation operators that can be used for mutation testing of actor programs.

In order to solve the current problems( expensive testing cost and low efficiency of test case generation) in mutation test for Simulink models,a mutation testing process and an optimized set of mutation operators were proposed for Simulink models based on program mutation according to the current mutation operators for the Simulink models. Experiments show that this set of mutation operators can effectively reduce the generation number of mutation models without prejudice to the mutation score of testing case set,thus it will effectively save the testing cost. Then a search-based test case generation method for Simulink models mutation testing was described. The test case generation problem was transformed into the objective function minimization problem,and the test cases which can kill the mutation models were ultimately obtained through the optimization of objective function by algorithm of simulated annealing. Finally,the application of a typical case for the method verified the correctness and effectiveness.

Software Testing is one of the most significant phases within the software development life cycle since software bugs can be costly and traumatic. However, the traditional software testing process is not enough on its own as some undiscovered faults might still exist due to the test cases’ inability to detect all underlying faults. Amidst the various proposed techniques of test suites’ efficiency detection comes mutation testing, one of the most effective approaches as declared by many researchers. Nevertheless, there is not enough research on how well the mutation testing tools adhere to the theory of mutation or how well their mutation operators are performing the tasks they were developed for. This research paper presents an investigative study on two different mutation testing tools for Java programming language, namely PIT and µJava. The study aims to point out the weaknesses and strengths of each tool involved through performing mutation testing on four different open-source Java programs to identify the best mutation tool among them. The study aims to further identify and compare the mutation operators of each tool by calculating the mutation score. That is, the operators’ performance is evaluated with the mutation score, with the presumption that the more prominent the number of killed mutants is, the higher the mutation score, thus the more effective the mutation operator and the affiliated tool.Â

This article proposes a cyber-security improvement plan for the DCS control system of nuclear power plants. Firstly, a brief introduction was given to the traditional architecture of DCS control systems of nuclear power plants. Secondly, the current cyber-security risks faced by DCS control systems in nuclear power plants were summarized, including identity authentication issues, access control issues, communication protocol issues, and data storage issues. Based on the cyber-security risks faced by the DCS control system in nuclear power plants, an improvement plan has been proposed for the DCS platform without increasing external cyber-security equipment. Firstly, regarding identity authentication, it is proposed that nuclear power plants have a very good physical protection that can effectively protect the operator station. However, for the engineer station, a dual factor identity authentication method needs to be added. Secondly, regarding access control, the shortcomings of role-based access control models were pointed out, and a location-based and task-based access control model was proposed. Then, in terms of security communication networks, the sensitive data range of nuclear power plants was analyzed, and communication was divided into internal communication and external communication. For internal communication, pre-stored keys can be used for encrypted communication. For external communication, certificates should be used for identity authentication, and then encrypted communication should be carried out. Finally, for data integrity, control system configurations can be saved through encryption. For passwords, they can be transmitted and saved through hash values.

Corrosion mitigation in coolant systems in nuclear power plants

Deregulation in the electricity market has resulted in a number of challenges in the nuclear power industry. Nuclear power plants must find innovative ways to remain competitive by reducing operating costs without jeopardizing safety. Instrumentation and Control (I&C) systems not only play important roles in plant operation, but also in reducing the cost of power generation while maintaining and/or enhancing safety. Therefore, it is extremely important that I&C systems are managed efficiently and economically. With the increasing use of digital technologies, new methods are needed to solve problems associated with various aspects of digital I&C systems. Probabilistic Safety Assessment (PSA) has proved to be an effective method for safety analysis and risk-based decisions, even though challenges are still present. This paper provides an overview of PSA applications in three areas of digital I&C systems in nuclear power plants. These areas are Graded Quality Assurance, Surveillance Testing, and Instrumentation and Control System Design. In addition, PSA application in the regulation of nuclear power plants that adopt digital I&C systems is also investigated.

Analytic study for physical protection system (PPS) in nuclear power plants (NPPs)

A probabilistic framework for mutation testing in deep neural networks

Critical systems have very stringent requirements on both security and safety. Recent mishaps such as the missing MH370 aircraft and the sunk Korean Sewol ferry go to show that our technology in safety and security risk assessment still need a more integrated approach. Nuclear plant meltdown in the recent Fukushima accident is also a typical example of insufficient risk assessments. This work is a case study on how a unified security and safety risk assessment methodology may be applied to a High Pressure Core Flooder (HPCF) system in a nuclear power plant. Individual risk security or safety assessments may overlook the possible higher risk associated with such critical systems. The case study shows how the proposed method provides a more accurate risk assessment compared to individual assessments.

The U.S. Nuclear Regulatory Commission (NRC) staff issued Revision 3 to NUREG-1482, “Guidelines for Inservice Testing at Nuclear Power Plants,” to assist nuclear power plant licensees in establishing a basic understanding of the regulatory basis for pump and valve inservice testing (IST) programs and dynamic restraints (snubbers) inservice examination and testing programs. Since the issuance of Revision 2 to NUREG-1482, certain tests and measurements required by earlier editions and addenda of the American Society of Mechanical Engineers (ASME) Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) have been clarified, updated, or revised. The revision to NUREG-1482 and its Appendix A incorporates and addresses those changes, and includes the IST programs guidelines related to new reactors. This revision includes a new Appendix B related to guidance for treatment of pumps, valves, and dynamic restraints (snubbers) during implementation of 10 CFR 50.69, “Risk-Informed Categorization and Treatment of Structures, Systems, and Components for Nuclear Power Plants.” The revised guidance incorporates lessons learned and experience gained since the previous revision to NUREG-1482. This paper provides an overview of the contents of NUREG-1482 and those changes, and discusses how they affect NRC guidance on implementing pump and valve IST programs, and dynamic restraint (snubber) inservice examination, testing and service life monitoring programs. This paper highlights important changes to NUREG-1482, but is not intended to provide a complete record of all changes to the document. The NRC intends to continue to develop and improve its guidance on IST and inservice inspection (ISI) methods through active participation in the ASME OM Code consensus process; interactions with various technical organization and user groups; and periodic updates of NRC-published guidance and issuance of generic communications as the need arises.

As an important barrier to prevent adversaries from destroying nuclear facilities or transferring nuclear materials, the cyber security of physical protection systems in nuclear power plants are receiving increasing attention under the current digital, networked and intelligent development trend in the world. In this paper, the authors analyze the cyber security risks faced by the physical protection systems and countermeasures, propose the idea of building an cyber security test platform for physical protection systems based on digital twin technology, and explore relevant key technologies, which provides a new perspective for the cyber security protection of physical protection systems in nuclear power plants around the world.

DC power system of the nuclear power plant is used to supply DC loads for engineered safety featured instrumentation and control such as inverter, power system control and indication, and station annunciation [1]. Batteries of DC power system of the nuclear power plant uses lead-acid batteries in present, but new secondary batteries would be installed in nuclear power plant. This paper compares capacity design of lead-acid battery bank and super capacitor battery hybrid energy storage bank, when the battery was connected directly in parallel with the super capacitor. In addition, duty cycle diagram of class 1E DC power system and characteristic of super capacitor battery hybrid energy storage device are analyzed.

Water/electricity cogeneration system in nuclear power plants and its peaking operation modes are analyzed in this work. The large-scale water/electricity cogeneration system can use the valley nuclear power during nighttime for seawater desalination, which can improve the peaking capacity, decrease desalination water cost and alleviate the water shortage in coastal cities. The peaking operation mode results show that the reverse osmosis desalination system runs better with variable load mode "12-1-10-1" (day 50% - night 100%) under the full load operation of nuclear reactor. In this mode, the peaking capacity of the water/electricity cogeneration system is 33%, the desalination water cost is 3.49 Yuan/m3 and the peaking cost is 65 Yuan/MWh. Development of the large-scale water/electricity cogeneration system in nuclear power plants has multiple benefits in China.