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Part 851 & Vacuum Systems

W.R. CaseyNSLS-II Project

Brookhaven National LaboratoryAugust 12, 2008

Office of Science

Accelerator Safety Workshop

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Vacuum System Design Issue

• Part 851 defines a vacuum system as a pressure system because of the potential for back-pressurization which invokes ASME Pressure Vessel Code, Section VIII

• Discussed at length at SC sponsored Accelerator Safety Workshop held 8/07

• Uncertainty was expressed regarding interpretation and implementation of requirement

• Potential impact to design of NSLS-II and other new accelerators was noted

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Approach to Addressing Pressure System Requirements for Vacuum Systems

• Developed during break-out session at Accelerator Safety Workshop• ORNL, BNL, ANL, LANL, TJNL, and others

• Prevent pressure differential greater than 15 psig through use of pressure relief devices (prevent over-pressurization if accidentally backfilled)

• Develop guidance that defines the design, fabrication, inspection, & test requirements for a vacuum vessel.

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Approach to Addressing Pressure System Requirements for Vacuum Systems (cont.)

• Form a working group to further develop this guidance.

• Issue guidance as an Office of Science document, most likely as an attachment to the Implementing Guidance for the DOE Accelerator Safety Order 420.2B.

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Status of Effort

• Working Group was formed Jan. 2008

• Technical issues were discussed during 6 conference calls from January to April.

• Six drafts of consensus standard were reviewed

• Final draft issued 6/17/08

• Edited version issued 7/17/2008

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Members of Working Group

• Argonne National Laboratory • Jeffrey T Collins • William F Toter

• Brookhaven National Laboratory • Robert Casey (Chair) • Edwin Haas • Dick Hseuh• Steven Kane • Edward Lessard • Sushil Sharma

• Fermi National Accelerator Laboratory • Daniel R Olis • David R Pushka

• Oak Ridge National Laboratory • Peter Ladd

• Stanford Accelerator Center • R. Keith Jobe

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Summary of Standard

• Key features of standard• Defines design requirements for all vacuum vessels• Requires ASME code compliance for vacuum vessels

subject to over pressurization > 15 psig• Defines requirements for equivalent level of safety when

ASME code does not apply (because of pressure range, vessel geometry, use of special materials, etc)

• Provides exemption for vacuum vessels with energy less than 100,000 joules or vessels with small dimensions (cross-sectional area less than 28.5 in2)

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Summary of Standard (cont.)

• Defines• Authority having jurisdiction• Engineering evaluation• Independent design professional• Pressure Safety Committee• Responsible vacuum system design engineer• Vacuum systems

– Category I– Category II– Category III

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Summary of Standard (cont.)

• Defines responsibilities and qualification requirements for the responsible design engineer, independent reviewer, authority having jurisdiction, and Pressure Safety Committee

• Establishes requirements for• Design• Design review• Fabrication

– Welding – Inspection– Testing

• Pressure Relief• Records

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Summary of Standard (cont.)

• Two Appendices

• Appendix A defines “Engineering Evaluations”

• Appendix B defines independent review requirements for Category III vacuum vessels

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Current Status

• The working group is very satisfied with its product – there was a true consensus.

• Definitions and requirements are being incorporated into BNL Pressure Safety requirements (other Labs are doing the same)

• However – we need for this standard to be recognized by the Office of Science and incorporated into the Accelerator Safety Order (or other appropriate documents)

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Next Step

• Review standard at break-out session

• Incorporate any additions, deletions, modifications to standard

• Identify responsibility and process for moving the document into the Office of Science

• Establish time line for official recognition of standard