Материал: Крючков Фундаменталс оф Нуцлеар Материалс Пхысицал Протецтион 2011

The initial events E1...E5 may occur at the location L1, E6 at L2, E7 and E8 at LЗ, E9 at L5 and E10 at L4. By analyzing the diagram we find that for the end event (the top one in the diagram) to occur, it will be enough to have any of the following six groups of events to take place:

1.EЗ.

2.E4.

3.E5.

4.E1 and E2.

5.E6 and E7.

6.E8, E9 and E10.

To transform the tree of events into a tree of locations, one needs to identify which locations match the given events. For example, the group of events numbered 6 (E8, E9 and E10) matches the locations LЗ, L4 and L5. Therefore, the locations that match the obtained six groups of events are:

This means that acts of sabotage that may lead to the said end event may take place either at the location Ll or at L2 and LЗ (at a time) or at LЗ, L4 and L5.

Now the tree of locations is plotted. The next step is to identify the smallest possible groups of locations (smallest possible critical groups) the protection of which will prevent the said end event (hazardous consequence) from taking place. One of such groups is, say, the combination of Ll and LЗ. This group is distinctive in that it shares members with all of the earlier identified groups, the location of which may be initiated by the accomplishment of the end event, i.e. with groups:

1.Ll.

2.L2 and LЗ.

3.LЗ, L4 and L5.

An analysis shows that no radioactivity escape will occur if the attacker access to any of the following three groups of locations is excluded:

1.Ll and LЗ.

2.Ll, L2 and L4.

3.Ll, L2 and L5.

These groups are called the protection groups.

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When choosing a particular group for taking provisions for its physical protection requires the cost of these and their influence on the NF operation to be taken into account.

Similar though simpler examples may be also given for the case of NM theft.

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CHAPTER 8

PPS EFFICIENCY ASSESMENT*

To objectively assess a system for being fit to perform the tasks it is assigned to, one needs to possess an efficiency assessment technique for this system. Such techniques may have a quality basis but are preferably to be based on quantitative indicators which enable different system versions to be compared [1].

As a property of a particular class of systems, efficiency depends on the specific features of these systems. Thus, in particular, the following definition may be used as applied to physical protection systems.

Efficiency, as applied to a PPS, is a property of the system which consists in the PPS capability to counter the attacker acts with respect to nuclear material, nuclear facilities, other NI vulnerabilities and physically protected items given the threats and the attacker models identified in the NI vulnerability analysis. The desired PPS efficiency level is achieved through a combination of activities undertaken to monitor and analyze the PPS operations in accomplishing its tasks of ensuring physical protection and define the ways for improving the PPS efficiency or maintaining same as required.

For a unified approach to efficiency assessment, respective procedures are developed.

To be determined, the efficiency of a PPS needs its capability to suppress unauthorized attacker acts to be assessed. Terminologically, “ to suppress” means the guard force timely reaching the objecti ve (the point) for the attacker to be neutralized.

The efficiency assessment has the following objectives:

∙identification of the PPS elements by defeating which the attacker has the best capability to commit an act of sabotage or NM theft;

∙consideration and identification of the most credible scenarios of the attacker actions for committing acts of sabotage or NM theft;

∙identification of the PPS points which are vulnerable though, formally, meet regulatory requirements;

∙analysis of the causes for the PPS vulnerabilities to emerge;

∙estimate of the probability for any attacker acts to be suppressed by the guard force in response to an external or internal threat alarm;

∙selection of the best designs at the PPS creation and upgrading stages;

* A contributor to this chapter was D.A. Skvortsov.

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∙formulation of proposals for the NI administration and guard force to perfect the PPS and its separate structural elements.

PPS efficiency assessment is mandatory at the PPS design stage in the PPS creation or perfection process. The quantitative indicator of efficiency may be used in the PPS design for comparing alternative PPS designs, including for supporting the feasibility of the PPS upgrade. To this end, the performance characteristics of the current PPS and the proposed PPS design are compared.

The efficiency of the existing PPS is assessed in full, involving a specialized organization, where no earlier PPS performance assessment data is available, including in the event that:

∙onsite changes are planned to the NI PPS;

∙the NI vulnerability analysis data requires so;

∙new NI vulnerabilities have been identified by state supervision or agency or onsite security control.

The above may have the form of both a complete PPS efficiency assessment and an update of the efficiency assessment data obtained during the PPS design.

The basis for carrying out the efficiency assessment in view of the scheduled site or NI PPS changes may be:

∙a change in the facility structure or the NI vulnerabilities and PPI array;

∙a change in the type or technique of guarding;

∙a change in the number of guard units;

∙relocation of guard forces;

∙other factors caused by a change in the guard force time of response to alarms;

∙a change in the structure or composition of engineered physical protection features.

The basis for carrying out the efficiency assessment based on vulnerability analysis data, as well as on the NI security government supervision or agency or onsite control results may be:

∙update of the attacker models;

∙update and identification of new vulnerabilities and PPIs as may be subject to unauthorized activities;

∙identification of new threats to the NI and ways for these to be realized;

∙a change in the NI processes;

∙identification of the PPS components failing to meet the requirements thereto;

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∙identification of the PPS components the defeat of which makes it possible for the attacker to commit acts of sabotage or theft of NM or other PPIs;

∙other factors rendering NM, the NF and other PPIs more vulnerable. As mentioned above, the key PPS efficiency assessment criterion is

assumed to be the PPS capability to suppress unauthorized attacker acts. The PPS efficiency is estimated by the quantitative indicators that define the probability of unauthorized attacker acts to be suppressed by the guard force in response to the alarm.

Performance indicators depend on the threats, attacker models and vulnerabilities identified by the NI vulnerability analysis. The PPS efficiency is estimated using:

∙a differentiated efficiency indicator that takes into account the probability of the attacker act against one target to be suppressed;

∙an integrated indicator that represents the PPS efficiency indicator, as averaged given the significance of targets, for the NI as the whole.

Efficiency assessment takes into account:

∙the probability of the attacker detection by engineered physical protection features (EPPF);

∙the time of the attacker delay by physical barriers (PB);

∙the time of the guard force and attacker movements over the nuclear site;

∙the mutual arrangement of facilities (probability of determining the attacker movement direction);

∙the presence of visual surveillance systems and facilities;

∙the presence of intrusion identification facilities (exclusion zones, seals);

∙the tactics of the guard force actions;

∙the equipment used by the attacker (vehicles, tools, weapons and so

on).

Efficiency assessment is based on an event and time analysis of the conflict developments in the “guard – attacker” sys tem during an external and an internal threat.

The attacker targets are assumed to be only fixed.

The PPS efficiency shall be assessed for two types of the attacker acts:

∙a theft of NM and other physically protected items;

∙an act of sabotage against NM, the NF or an NM storage point.

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