Attached is a policy and procedure regarding APS Beamline Shielding Configuration Control.

For additional information contact:

Julie Cross - User Technical Interface
[email protected]
Telephone - 630.252.0592

Updated: May 18, 2011

Policy

Scope: This policy addresses only the administrative controls that the APS has put into place to ensure the integrity of beamline shielding.

Definitions:

APS Configuration Controls are the administrative controls, (i.e., the policies and procedures) that the APS has placed on beamline shielding components.

White beam is an x-ray beam whose spectral characteristics have not been modified from those produced by an insertion device or bending magnet source, except through the introduction of filters. For the purposes of this policy, the term white beam includes those x-ray beams that have been reflected from a mirror but have not passed through a monochromator.

Monochromatic beam is an x-ray beam whose spectral properties have been defined by the use of a monochromator to select an energy range (and corresponding harmonics) with a relatively narrow bandwidth, typically less than a few percent.

Under APS Configuration Controls, components fall into two categories:

1. Critical components: Beamline components used to stop, for shielding purposes, the white synchrotron and bremsstrahlung radiation.
   • These include:
     • white beam stops and shutters
     • bremsstrahlung stops and collimators
     • masks that protect the above components.
   • The APS will verify the alignment of these components, and their shielding integrity will be verified by a radiation survey.
   • These components will be tagged with a red "CRITICAL COMPONENTS" sign.
2. Non-critical components: Portions of the shielding system that are not directly exposed to the white synchrotron or bremsstrahlung radiation.
   • These include:
     • station shielding
     • shielded beam transport
     • temporary local station shielding
   • The APS will verify the shielding integrity of these components with a radiation survey.
   • These components will be tagged with a yellow “SHIELDING UNDER CONFIGURATION CONTROL” sign.

Because of the higher risks associated with exposure to white synchrotron radiation, it is the APS policy that the alignment of critical components be verified by the APS. Also, these components will be tagged with a red sign that will identify them as critical components.

Functionally, each white beam shutter and stop must stop the x-radiation as well as manage the thermal load of the white beam. Though the mechanical assemblies that perform these functions may be physically separated and may have different alignment tolerances; both parts of the assembly shall be treated as critical components.

In addition to critical components, there are many components that are exposed to the direct white synchrotron beam but whose presence and performance does not impact personnel safety. Such components include, but are not limited to, filters, white beam slits, monochromators, and mirrors.

Procedure

As part of the beamline commissioning process:

1. The CAT prepares a list of components under APS Configuration Control, which is consistent with the approved operation envelope of the beamline; the list is approved by the APS and posted in the beamline cabinet at the end of the sector.
2. Components under APS Configuration Control, both critical and non-critical, will be tagged by a Floor Coordinator.

Each white beam transport is to be tagged as under APS Configuration Control. For transport designs with the vacuum pipe mounted within a shielding enclosure, each removable cover shall be tagged. For transports with lead shielding as an integral part of the vacuum spool pieces, the control tags shall be installed on each section of shielded transport and on each exposed flange or flange cover.

All of the front-end components housed in the First Optics Enclosure (FOE) will be put under APS Configuration Control and a tag placed on the support table.

Before a component under APS Configuration Control may be moved or worked on, a Configuration Control Work Permit (CCWP) must be completed, approved by a Floor Coordinator, and posted in the beamline cabinet. Refer to the Configuration Control Work Permit Policy and Procedure for further details.