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Changes in Access Requirements for NSLS Experimental Building (Bldg. 725)

Effective Oct. 1, 2003 the "Controlled Area" postings on all doors to the experimental floor in Building 725 will be revised to remove the requirement for TLDs for access. (This change does not apply to Building 729, site of the DUV-FEL.) The implication of this change in access requirements is as follows:

With this change many personnel will not need to wear a TLD to work on the experimental floor. This change will have biggest impact on short-term users running typical experiments at the NSLS.

Everyone should be aware that all other access requirements remain in effect. It is particularly important to remember that all personnel on the floor must have appropriate NSLS facility specific and radiological training unless escorted as described in the NSLS escort policy. There are no exceptions to this requirement.

The justification for this change in access requirements is derived from the extensive personnel monitoring records over the past 4 1/2 years which clearly demonstrate that radiological exposure to personnel working in the building is minimal, well below the DOE regulations requiring personnel dosimetry. The change is quite helpful for our users in that our requirements are now similar to those at other DOE Light Sources.

Who will still need to wear a TLD?

  • NSLS and beam line staff and long term users routinely working on the floor throughout the year are required to wear a TLD.


  • There are several special cases that will require a person working on the floor to wear a TLD:
    • Work with radioactive materials (including sealed sources) or other work as required through the safety approval process
    • Work in a location on the experimental floor posted as requiring a TLD
    • Women with a declared pregnancy working on the experimental floor
    • Minors working on the experimental floor
    • Personnel escorting minors on a tour of the experimental floor

Why are some people required to wear a TLD?

Monitoring of radiological conditions on the experimental floor is provided by the fixed area radiation dosimeters located throughout the experimental area. As a supplement to this network of fixed dosimeters, NSLS management will require TLDs for all staff routinely working on the experimental floor throughout the year. Although the area monitoring program is extensive, this policy will ensure several hundred additional data points from personnel working in every location of the building and permit additional documentation of radiological floor conditions. We are in the process of identifying personnel "routinely working on the experimental floor", but this category will primarily consist of permanent PRT beam line staff and NSLS scientific, professional, and technical staff who work on the floor. This group of people will continue to wear TLDs.

The dose limits for pregnant women and minors are much lower than those for other workers. Even though exposures on the floor are minimal, as an added precaution we will also require dosimeters for women with a declared pregnancy and for all minors working on the experimental floor. In addition, we are required by DOE regulations to provide dosimetry for personnel working with radioactive material or for work in locations with elevated radiation levels. These cases should be identified through the safety review process.

This new access policy will reduce the number of persons wearing TLDs from ~2000 per year to ~ 300. However, it is not intended to limit dosimetry for personnel with special needs or concerns. Please contact NSLS ESH personnel if you desire dosimetry while at the NSLS, or if you would like to discuss this policy further.