Nuclear Application Maps (11 of 14) – Clearances

Clearances is sometimes known as Lock out / Tag out and is associated with the process of isolation of potentially dangerous equipment due to electrical, mechanical, chemical, hydraulic, heat and radiation sources that pose hazards to people and the environment. 

A Clearance consists of three principal parts:

The Clearances application is closely coupled with the Work Order TrackingQuick Work Orders and Permits applications throughout the lifecycle of both the clearance and its work orders starting with the creation of the clearance requests from these work order based applications. Maximo supports both simple and complex clearances, ones that may involve many components. Multiple clearances can be grouped to the same parent clearance and the Clearance application also supports shared tags across multiple clearances.

There are three types of clearance. A template is used with Preventive Maintenance records to pre-plan the clearance that will be needed when a work order is generated from the PM. A working clearance is used with a work order, it may be generated as part of the PM work generation process. An admin clearance is used with operational activities that comply with regulatory requirements, you cannot add work orders to an admin clearance.

You create a clearance and identify the Location or Asset the clearance is designed to isolate. This may be a location or asset anywhere in the hierarchy. As part of the Application you identify the components that define the clearance boundary and for each component the position that it needs to be configured to and the tags that will be applied. For each record you set the application sequence for the tagging operations.

As you add the components and tags as part of the Application process, Maximo will enter a similar record for the Restoration process. You will need to enter the component position and the restoration sequence for the restoration process.

One or more work orders or permits that have requested clearance protection and have raised a clearance request can be added to the clearance. Approval will be required to add the work orders, approval will also be needed to remove a work order from clearance protection. 

The operational impact of the clearance can be determined. This involves associating relevant Tech Specs and identifying the components that will become unavailable during the clearance. The operational history is collected on the locations and assets as a result of the clearance.

There are many settings and functions associated with clearances. You can specify which tag types are compatible with each other. Tags can be shared between multiple clearances, but certain tags may not be sharable, and if they are not shareable you can prevent multiple tags of the same type being applied to the same component by two or more clearances. You can check when there are tag conflicts during the Application or Restoration processes that may occur when multiple clearances reference the same boundary components, for example a switch cannot be both open and closed at the same time. Clearance settings are defined at the site level in the Organizations application.

A clearance has a set of statuses where certain actions can only be performed at each status. There is tight control through the whole clearance lifecycle, that goes beyond the changing of the clearance status. Each tagging action during both application and restoration processes is controlled and optionally independently verified. Control of the clearance process after application tags have been applied will be handed over to the maintenance team and the related work orders. Maintenance supervisors will need to independently verify that it is safe to perform the work required in a process step called Craft Approval. Technicians will sign on/off of clearance protection as part of each work order and when they have indicated work completion a process of releasing control of the work orders back to operations is followed and this must happen before the restoration process can begin.

Clearances are under revision control and a new revision may require the removal of some work orders or the addition of other work orders. A revision may change the clearance boundary or the work orders under clearance protection, and the clearance revision will similarly need to go through a reassessment of the tagging requirements involving both operations and maintenance.

Only one revision to a clearance can exist at any one time. However, the Clearances application supports revision plans which are the prestaging of clearance boundary changes and their related work orders, which can then be included into a revision at a later time. The revision plan can be approved by operations while maintenance continues to work on other work orders in the area of the clearance boundary. When maintenance is ready to interrupt their work programme, then final operations approval can be sought, plant configuration and tagging activities completed and the new protection area handed over to maintenance to continue work. The prestaging of clearance boundary changes can help to increase the performance of the work programme.

Multiple revision plans can exist for a clearance. A clearance with multiple revision plans can be copied to create a template clearance, and a template clearance with multiple revision plans can be used to create a working clearance. Tag sharing or conflict checking does not take place on a revision plan, only once the revision plan has been copied into a revision. 

The Clearances application supports temporary lifts which may be required for component testing. It involves the removal of one or more tags from a clearance for a temporary period, it may also include the changing of a position of a previously tagged component. A temporary lift may add test tags and then remove these test tags after testing has completed. A temporary lift can also be prepared ahead of time. As the name suggests a temporary lift has a limited duration. 

If testing is successful, the tags do not need to be rehung and the tags can be restored. Alternatively, if rework is necessary the components are repositioned, and original tags rehung and reverified. The repositioning and reverification of the original tags can also occur if the tests are successful and the test team are moving on to perform other temporary lifts within the same clearance. 

Special use locations are Locations of type ADMIN that are used for instructions, notes, lock boxes, key rings, etc, and which are used in the tag application and restoration sequences. For example, you may wish an operator to validate that they have read an instruction before applying or restoring tags. Special use locations must be registered in the Organizations application and may then be used multiple times in an application or restoration sequence.

During the Restoration process you can select a restoration condition and use a Lineup Plan to provide restoration details. The removal of tags and the repositioning of components as part of the clearance restoration process can provide credits to a Lineup created from the Lineup Plan.

The Clearance application is feature rich and because of the safety nature of the processes it is the most complex of all the Maximo for Nuclear Power applications.

The Clearance Groups application will be used only if a site-based setting has indicated its use, if so, it will be a mandatory field on the Clearance. It is a simple application that is used to identify a clearance group and its main purpose is for tag sharing. Only clearances of the same clearance group will be able to share the same tags.

The Clearances Kiosk application is used by operators on the floor who need to record when tags have been applied for the components they have configured or to independently verify the tags and component positions configured by other operators. The Clearances Kiosk application is used both in the Application of tags and the Restoration of tags, only two of the four tabs are shown depending on which phase the clearance is in. The same Maximo session allows multiple users to log on in turn and complete the details under their username. 

The Sign On/Off application is used by maintenance personnel or other users who need to sign on to a clearance in order to be provided with clearance protection. The sign on/off process occurs after clearance tags have been applied and copied to the work order and after craft approval has been given on the work order. The maintenance supervisor registers the user to the work order before they can sign on to it for the first time. The application allows the same Maximo session to be used by multiple users who log on in turn and complete the details under their username.

The Lock Out / Tag Out application is not compatible with Clearances and should be either removed from all users or removed from those security groups who will be using the Clearances application.

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