The BNL National Synchrotron Light Sourceshpschapters.org/sections/accelerator/casey-the bnl light...

1 BROOKHAVEN SCIENCE ASSOCIATES

The BNL National Synchrotron Light Sources

Bob CaseySenior Health Physicist

NSLS-II ESH StaffJune 29, 2010


BNL Site


BNL Site in 1947


“At the beginning of the last decade (1950) the shielding ofa high-energy accelerator was quite often considered as an afterthought or last-minute addition to the early experimental-program requirements.” – “S. Lindenbaum”


AGS Under Construction


AGS – 10 years later


Brief AGS History

• Construction started ~ 1956

• Achieved design energy 33 GeV – July, 1960

• Nobel prizes• Muon neutrino – 1962 experiment (Awarded in 1988)• CP Violation – 1963 experiment (Awarded in 1980)• J/Psi particle – 1974 experiment (awarded in 1976)

• Upgraded in intensity many times• Designed for 1 x 1010 p/p• Eventually 7.5 x 1013 p/p


Enough of proton machines

Lets talk about synchrotron radiation sources


Synchrotron Radiation• It had been recognized from laws of electrodynamics that

charged particles will emit radiation when direction or velocity is altered.

• A letter to the Physical Review in 1944 predicted that radiation emitted by electrons would establish a “limitation for maximally energy attainable” in synchrotrons.

• An electron synchrotron built by GE in 1946 observed the emitted and the term “synchrotron radiation” was developed.


Synchrotron Radiation (cont.)

• Considered a “nuisance” because of the limitations it imposed on maximum energies for circular machines

• However, scientists began to study the radiation and noted quickly the potential uses for research in absorption spectroscopy and fields.

• “Tantalus” began operation in 1968 as a synchrotron radiation source. It was a 12.5 GeV proton storage ring converted into a 240 MeV electron ring - first dedicated device.


Synchrotron Radiation (cont.)

• Other facilities (e.g. 540 MeV ring at Orsay, 250 MeV ring (SURF II) at NBS) adapted facilities for synchrotron radiation research

• Within the U.S., demand for synchrotron radiation research time at electron storage rings often conflicted with high energy physics demands.

• Solid state physicists at BNL recognized the importance of SR research and began an effort to develop wider support for the building of a dedicated synchrotron radiation source.


Chasman Green Lattice

• Chasman-Greene developed the first electron synchrotron magnet lattice that was intended to minimize the emittance of the beam – the double-bend achromat

• the Chasman-Greene lattice and its variation are the basis for most of today’s synchrotron sources

• An important figure of merit for a light source is its brilliance. The Chasman – Green lattice was very important in achieving high brilliance in SR beams.


NSLS Project Proposal

• Final proposal for the National Synchrotron Light Source submitted to ERDA in Feb. 1977

• Requested $24 million to build 2 rings• Construction to start Oct. 1, 1978• Project to be completed Oct. 1981

• Project was approved for design start Oct. 1, 1977


Ground-breaking - September 1978


Fall 1980


First Light - 1982


Early NSLS History

• NSLS was dedicated in fall 1982, but was suffering from a number of compromises imposed by the funding shortfall.• VUV was far from the planned beam current and life time,

but was operating with a limited program• X-ray had beam but required on-going improvements for

two years before able to support an experimental program. • Shielding was added as needed for linac, booster and VUV

• However, they persevered and within several years a very strong research program was established.


NSLS Now


NSLS

VUV RING• E = 0.8 GeV• εx = 155 nm• C = 51 m• I = 1 Amp

XRAY RING• E = 2.8 GeV• εx = 60 nm• C = 170 m• I = 0.3 Amp

Booster & Linac• E = 0.12 - 0.8 GeV• C = 28 m, 0.7 Hz• I = 0.01 Amp


So lets talk Radiation Safety


Three Key NSLS Radiation Safety Issues

• How do you handle 2500 users involved in 1200 different experiments each year?

• How do you handle Hutch “Search and Secure” 100,000 times per year?

• How do you operate an accelerator with inadequate shielding?


Bill Thomlinson


Tom Dickinson


The Light Source User Community• Very diverse group

• different fields of research• different experiences

• Often inexperienced with synchrotrons and beam lines (UWOC)

• Often present at the facility for short periods of time, including week-ends and nights

• They arrive with their samples, sometimes with special equipment, & stay a day or two and then leave.


How do you handle 2500 Users a year?The NSLS Approach - Research Operations

• NSLS staff assigned full-time responsibility to provide operational ESH support and over-sight of beam lines and users• 9 operations coordinators (opcos) providing coverage 24/7• 5 ESH staff working normal hours

• Responsible for:• Safety review of experiments• Check-in and oversight of user groups at beam lines• Configuration control of shielding components, interlocks &

radiation safety barriers


Safety Review

• Details of each experiment must be submitted in advance for review by ESH professional

• Extended review required for complex experiments

• Submissions and reviews addressed through networked database.

• Experiments may not begin without ESH approval.


Check-in and Oversight of User Groups at Beam Lines

• Each experiment is enabled at beam line by Operations Coordinator following confirmation of:• ESH approval• Completion of all training (Building, ESH, and beam line specific)• Satisfaction of any other conditions established for the experiment during the safety

review

• All electrical equipment must be inspected for NRTL listing

• Overhead cranes and machine shops locked out – use restricted to authorized persons only.

• Two operations coordinators are on duty and make routine rounds through-out each shift.

• NSLS Safety Officer and other ESH staff routinely on floor through-out the day.


Beam Line Configuration Control

• Shielding & Radiation Safety Components• Any change requires Safety System permit approved by

Safety Officer• Start-up check-list completed by OpCo• Photographs to confirm configuration

• Interlock • Safety system permit required for work on system• Work by authorized personnel only• Re-test of system following any modification


X-29 Beam Line Configuration Control


X-29 beam line


Issue 2 - Hutch Search and Secure

• Previously at BNL, only departmental staff were authorized to search and secure a “high hazard” area

• It was very clear early in the research program that another approach was necessary at NSLS – it was simply not practical to require NSLS operations to secure every hutch following entry.

• Solution • Develop and implement hutch interlocks and “search and secure”

hardware that is simple to use and highly reliable• Authorize users and beam line staff to conduct search and secure


NSLS Interlock Principles• System should be fail-safe

• Loss of power• Short to ground• Open circuit

• System should be redundant – 2 chains independent of each other

• Redundant branches should be different• PLC on one chain, relay logic in 2nd chain• Different types of switches

• System should be readily testable

• System should be simple


Interlock History• System has proved highly reliable and simple to use

• No complete loss of protective function during 25 year history

• All interlocks are tested and recertified on a 6 month frequency. We recently sought extension of test frequency, but were unable to justify it after conducting failure mode analysis.


A Few Pictures of the Hutch Search and Secure


Hutch Entry


Hutch Door Prior to Entry


X -28 Hutch Following Entry


X-28 Hutch interior


Search and Secure History

No instances of improper search or interlock failure resulting in person in hazardous area with hutch “secured”


Issue 3 Operating Accelerators with Marginal Shielding

• Booster was assembled with less than optimum components and operated with high injection and extraction losses throughout its history. Near-by areas are subject to elevated radiation fields during booster operation.

• VUV ring was locally shielded with lead bricks. No neutron shields were initially provided. During injections, near-by areas are subject to elevated radiation fields.


Booster Enclosure


VUV Ring


Shielding Upgrades• Have only been marginally successful

• Radiation exposures have been successfully controlled by:• Limiting times of Booster operations

– VUV fills during normal hours are: 8:00, 12:30, and 5:30– X-ray fills are 7:00 a.m. and 7 p.m.

• VUV floor locked out during commissioning periods following some maintenance periods

• Users on VUV floor are required to stand back from machine and injection line during fills

• Area radiation monitors installed through-out the building, including many offices, with alarms locally and in control room.


Brief NSLS Summary

• First light source designed and dedicated as a light source for research

• Slow and challenging start, but eventually extremely successful as a research facility.

• 2 Nobel prizes have been won based on research conducted at NSLS

• Excellent safety record – ESH program regarded as one of the best

• Many new synchrotron radiation facilities have been built since the mid 80s with improved performance and NSLS is no longer state of the art.

• Upgrade efforts started in early 2000’s in order to provide state of the art capability for it users.


Which Brings Us to NSLS-II


1

Light Source Emittance


NSLS-II Project ScopeAccelerator Systems

• Storage Ring (~ ½ mile in circumference),200 MeV linac, and 3 GeV booster• 3 hour life-time • 3 GeV, 500 mA, top-off injection• Ultra-low emittance: εx, εy = 0.6, 0.008 nm-rad• Small beam size: σy = 2.9 µm, σx = 33 µm, σ’y = 2.7 µrad, σ’x = 17 µrad

Conventional Facilities• Ring Building and Service Buildings (~ 400,000 gsf)• Laboratory/Office Buildings (LOBs) (190,000 gsf)

Beam Lines• Initial six insertion device beam lines• Capable of hosting at least 58 beam lines

Total Project Cost: $912M


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Average BrightnessNSLS-II vs. NSLS


Start of Construction Celebration

From left to right: BHSO Manager Mike Holland, Stony Brook President Shirley Strum Kenny, NSLS-II Federal Project Director FrankCrescenzo, NSLS-II Project Director Steve Dierker, DOE Deputy Director for Science Pat Dehmer, Senator Kirsten Gillibrand, Senator Charles Schumer, BNL Director Sam Aronson, Battelle Executive Vice President Ron Townsend

June 15, 2009


Construction ProgressJune 2009

April 2010


Construction Progress

Vehicle Tunnel

Structural Steel SR TunnelSR Roof

SR Ratchet WallEntrance Lobby

May 2010


Status of NSLS-II Project• Excellent progress

• Project is 30% complete as of end of May 2010

• On schedule and on budget• All major procurements, totaling $214M to date, were awarded within 1% of planned cost

• Key Project MilestonesJuly 2012 Start Linac CommissioningOctober 2012 Start Booster CommissioningOct 2013 Start Accelerator Commissioning Jun 2014 Early Project Completion; Beam Available to Beam linesJun 2015 CD-4, Approve Start of Operations


Important Radiation Safety Issues

• Build on NSLS strengths• Include ESH in all engineering design reviews• Adopt beam line safety review process• Adopt training and work planning programs• Adopt Research Operations model

• Make sure that we get the shielding right

• Examine interlock design for improvements


Make Sure the Shielding is Right

• Get experienced people – PK Job and Casey

• Document and present all analyses

• Conduct frequent peer review


Document and Present all Analyses

• Linac Shields, NSLS II- TN 12• Booster & Storage Ring Shields, NSLS II – TN 13• Storage Ring Supplemental Shielding – NSLS TN 21• Beam lines and Front Ends, NSLS II – TN 14• Activation Analysis, NSLS II – TN 15 & 1• Preliminary Material Requirement for Supplemental Shields

–TN 31• Shielding Estimates for First Optics Enclosures,

Monochromatic Stations, and Monochromatic Beam Transports for the NSLSII Beam lines – TN 33

• Revised Shielding Estimates for the NSLS-II Beam lines at 3.0 GeV Beam Energy – TN 40


Document and Present all Analyses (cont.)

• Guidelines for NSLS-II Beam Lines and Front-end Radiation Shielding Design • Final Design Parameters and Beam Loss Assumptions for Shielding Calculations of

Accelerator Enclosures – Jan. 31, 2008• Bulk Shielding Requirements for Final Design of NSLS-II Accelerator Enclosures – Feb.

19, 2008 • Redundancy Requirements for Critical Devices; Presentation at RadSynch Workshop

IV; 6/08• “Shielding Requirements for NSLS-II” – Presented at Mid-year HP Society; 1/08• “Shielding Requirements for NSLS-II Beam Lines” – Presented at ICRS-11; 4/08• ESH Chapter in NSLS-II Preliminary Design Report• NSLS-II Preliminary Safety Assessment Document• “ALARA Analysis of NSLS-II Shield Designs” presented at RadSynch Workshop, 4/09 • The Effectiveness of Thin Low-Z Scrapers in the Electron Storage Rings, RadSynch

Workshop, 4/09• Activation Analysis of Soil, Air and Water near the NSLS II Accelerator Enclosures,

RadSynch Workshop, 4/09


Conduct Frequent Peer Review

• We have hosted 3 radiological safety workshops• March, 2007• April, 2008• June, 2010

• Workshop participants include radiation physicists from SLAC, ALS, and ESRF; and accelerator physicists from APS and ALS

• Workshops have been very valuable and help to examine our assumptions and analysis

• In addition we are subject to DOE project review (Lehman review) 1 – 2 times per year


Examination of Interlock Design


Evaluation of Safety Interlock Integrity

• Performed by independent contractor specializing in fault tree analysis using ISA 84 principles

• Assumes interlock test interval of one year

• Fault tree analysis with specialized computer software used to evaluate probability of failure

• Generic fault rates used for components where rates are not available ( i.e. solenoids and some switches)


Evaluation of Safety Interlock Integrity (cont.)• Examined probability of failure for 3 scenarios

• A person enters an enclosure without using the control system to shut down the beam (breaks a door open to enter the protective enclosure) while beam is present.

• A person follows proper procedures to enter an enclosure, but due to failures within the safety system, beam is present on entry.

• A person has entered an enclosure using proper procedures and the control and safety systems have reacted properly. Then, while the individual is present, malfunction of the safety systems allows the safety shutters to open and exposes the person to beam.


Conclusions of study:

• Previous design significantly improved by 4 modifications

– Adding a second critical device

– Separating safety and control functions

– Use of Safety PLC’s logic vs. relay logic

– Use of diverse shutter position sensing

• All scenarios have probability of failure < 10 -05


Results of Interlock Failure Analysis

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