Physical protection of hardware and software -: Linking access control systems with operational computer systems

The existence and use of software and networks have generated another possibility for perpetrators to influence systems in nuclear facilities or to prepare malevolent acts. Data security has become an element of physical protection plans, not as an end in itself but as a means to achieve physical protection objectives. Physical protection measures are additional measures, which become necessary when other measures that have to be taken (e.g. in compliance with international standards) are insufficient to prevent a hazard to the protection goals through data manipulation by software and hardware. In planning or assessing data protection measures for the purpose of physical protection, it is necessary to differentiate between applications which can, if manipulated, directly endanger the protection goals, e.g. safety control systems, and those applications which only have an indirect effect, e.g. material accountancy and access control systems. The following questions have to be considered: Which possibilities of influencing systems via software and data manipulation need to be considered? What effects can software and data manipulation have on the protection goals? Will the operating personnel act appropriately, e.g. by using conventional gauges? The problem ranges from conventional data security to the human factor and classical safety related analyses. The importance of software protection is growing. In particular, because of ageing of components, the existing instrumentation and control systems with their fixed wiring and discrete elements will have to be updated. Computerized access control systems play an eminent role in the physical protection of a nuclear facility. Therefore, most systems are operated as islands. The paper shows that linking of certain systems with other computer systems is possible without inadmissible drawbacks for the physical protection level. It is shown by means of the example of linking together the computer networks of access control, health physics, the flexitime system, the key administration and the operational management system that such linking of systems in nuclear facilities has hidden advantages for all participants.