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Radiation Safety

VIEWS: 62 PAGES: 41

									Radiation Safety

Rick Donahue
(Hiroshi Nishimura, Dave Robin, Christoph Steier, Bob Mueller, Brian Fairchild)

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

1

Radiation Safety - Outline
• Current Radiation Practice and Results
—Description of monitoring systems —Characterize stray radiation fields

• Issues With Top-off mode
—Injected beam loss —Stored beam loss —Rf trips

• Future Plan
—Further simulations/measurements —Radiation Safety Review

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

2

Radiation Monitoring
• Description of monitoring systems: ACTIVE
—Interlocked neutron/gamma monitors ~12 (24/7) —Beamline 1st optics gamma monitors ~25 (24/7) PASSIVE —In-close dosimeters ~50 (24/7) —Peripheral dosimeters ~12 (24/7) —Badged staff (not required, change in 1996) ~50

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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1. In-close Dosimeters
ALS 3-Pack Summary Report
Location De scription AL S-0 1 AL S-0 2 AL S-0 3 AL S-0 4 AL S-0 5 AL S-0 6 AL S-0 7 AL S-0 8 AL S-0 9 AL S-1 0 AL S-1 1 AL S-1 2 AL S-1 3 AL S-1 4 AL S-1 5 AL S-1 6 AL S-1 7 AL S-1 8 AL S-1 9 AL S-2 0 AL S-2 1 AL S-2 2 AL S-2 3 AL S-2 4 AL S-2 5 AL S-2 6 AL S-2 7 AL S-2 8 AL S-2 9 AL S-3 0 Issue 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 1/3/08 Re turn 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8 2/20 /0 8

Januar y, 2004
Gamma :

CR-39 i n fie ld fro m 1 1/03-1/04 Ne utron : CR-39 # 0 7 0 2 0 0 4 0 0 0 3 0 0 0 2 13 1 2 2 0 1 1 7 2 3 16 6 0 9 1

Ne t (mrad) 3 2 0 0 0 0 0 0 0 0 0 0 0 0 0 8 0 4 0 0 0 0 0 2 0 7 0 0 0 0

Gamma - 6 wks Neutron - 3-4 mo Includes Accelerator Physics Shifts

B/L 4.0

B/L3.1

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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In-close Dosimeters
ALS 3-Pack Summary Report
Location De scription AL S-0 1 AL S-0 2 AL S-0 3 AL S-0 4 AL S-0 5 AL S-0 6 AL S-0 7 AL S-0 8 AL S-0 9 AL S-1 0 AL S-1 1 AL S-1 2 AL S-1 3 AL S-1 4 AL S-1 5 AL S-1 6 AL S-1 7 AL S-1 8 AL S-1 9 AL S-2 0 AL S-2 1 AL S-2 2 AL S-2 3 AL S-2 4 AL S-2 5 AL S-2 6 AL S-2 7 AL S-2 8 AL S-2 9 AL S-3 0 Issue 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 2/2/08 Re turn 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8 3/10 /0 8

Fe bruary, 2004
Gamma :

CR-39 i n fie ld fro m 1 2/03-2/04 Ne utron : CR-39 # 7 5 6 10 2 2 11 4 12 10 0 6 6 10 3 8 13 11 6 4 14 11 14 16 7 20 12 12 1 4

Ne t (mrad) 3 2 0 0 0 0 0 0 0 2 0 1 0 0 0 8 2 5 0 0 0 0 0 1 0 7 2 0 0 0

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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In-close Dosimeters
ALS 3-Pack Summary Report
Location De scription AL S-0 1 AL S-0 2 AL S-0 3 AL S-0 4 AL S-0 5 AL S-0 6 AL S-0 7 AL S-0 8 AL S-0 9 AL S-1 0 AL S-1 1 AL S-1 2 AL S-1 3 AL S-1 4 AL S-1 5 AL S-1 6 AL S-1 7 AL S-1 8 AL S-1 9 AL S-2 0 AL S-2 1 AL S-2 2 AL S-2 3 AL S-2 4 AL S-2 5 AL S-2 6 AL S-2 7 AL S-2 8 AL S-2 9 AL S-3 0 AL S-3 4 AL S-3 5 AL S-3 7 AL S-3 8 AL S-3 9 AL S-4 0 AL S-4 1 AL S-4 2 AL S-4 3 AL S-4 4 AL S-4 5 AL S-4 6 AL S-4 7 Co ntrol Issue 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 4/2/08 Re turn 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8 7/31 /0 8

Apr il, 2004
Gamma :

CR-39 i n fie ld from 2/04-4/04 Ne utron : CR-39 # 0 0 0 0 0 0 0 0 0 3 3 0 0 0 7 7 0 0 0 0 0 0 36 * 0 0 48 * 24 * 0 80 * 12 (mre m)

Ne t (mrad) 2 0 0 0 0 0 0 0 2 2 6 15 0 13 0 0 4 11 0 0 0 0 3 3 0 12 0 0 0 0 25 4 0 0 0 0 0 0 0 0 0 0 0 0

4.0

3.1

Sec 1 Vac nook

* suspecte d bad resul t

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Other dosimetry results
• 12 peripheral neutron/gamma monitors: nothing above background in 10+ years operation. • 50 badged permanent staff: nothing above background (directly related to ALS operations) in 10+ years operation.

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Top-off Radiation Issues/challenges
1. Injected Beam – PSS now open • Injected e- go down beamline? • Injected e- strike the storage ring vacuum chamber near the beamlines inside ring? 2. Stored Beam - (1440 mA/shft)/(200 mA/shft) ~ 10X 3. Rf Trips - average I from 250 to 500 mA, so ~ 2X First is unique to top-off. Second and third are important, known, but not unique.
Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Inject down beamline - how bad?

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Injected e- Down Beamline?
Simulations: backwards tracking from the beam line towards the injector (H Nishimura) - same approach taken at APS and ESRF : • Assume stored beam(!) • Using apertures in the beamline front end, determine the available phase space of the beamline relative to the storage ring. This determines actual starting pt. • Beginning at the beamline, track particles backwards towards the injector covering complete beamline phase space and vary the e- energy. • See if e- can reach the injection point • If no condition can reach the injection point then  injected e- can not reach the beamline.
Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004 15

Worst case – Beamline 2.1
• • • Worst case should be beamline 2.1 (being designed). No ID’s in SR01, SR02, SR03. Sampled phase space of b/l 2.1 exit port set by apertures up-stream and down-stream. Tracking done with
— realistic field representations — Wide range of magnetic settings (quad +/-20%, etc)

•

Track backwards and plot maximum distance a particle reaches as a function of energy P/P0 (injected/stored).

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Calculate here

―Inject‖ here

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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BL6.1 - identical to BL2.1

Line N A B C D

T(rad) 0.240517 0.326554 0.242500 0.236502 0.200081

T(deg) 13.780577 18.710122 13.894194 13.550535 11.463770

dT(rad) 0.000000 0.086037 0.001983 -0.004015 -0.040436

Point 0 3 1 4 2

Xo(m) 0.334870 0.392060 0.320070 0.284490 0.278820

dX(m) 0.000000 0.057190 -0.014800 -0.050380 -0.056050

Z(m) -0.000790 0.000960 0.000010 0.000010 0.000010

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Tracking - starting point

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Transverse Phase of the Beam that Reaches SR02C BPM5
350 300 250 200
Px (mrad)

BL2.1

150 100 50 0 -50 -100 -150 -100 -50 0 50 100 150 200 250 300 350 400 450
X (mm)

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Inverse Tracking from BL2.1
25

20

Smax (m)

15

10

5

0 0.0 0.2 0.4 0.6 0.8 1.0 P/Po 1.2 1.4 1.6 1.8 2.0

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Inverse Tracking from BL2.1
BL2.1

400
P= 53% P= 61% P=100% P=140% P=200% Xin Xout

300

200
X (mm)

100
“Real” Injection Point Straight Section

0

BR01C BPM5

SR01C B2

SR01C B3

SR01C B1

SR02C B2

SR02C B1

-100

-200 0 5
SR01

10 S (m)
Berkeley Lab

15

20
SR02

25

Top Off CDR Review, Nov 22-23, 2004

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Superbends – Unique to the ALS
• Of the 36 dipoles, there are three Superbend magnets that have individual supplies. Could a magnet fail (quench) shortly before injection causing electrons to pass down the beam pipe? — Stored beam loss occurs when Superbend reaches 99% of nominal field. — Field must be 80% nominal to go down beamline (100% = 10o, 80% = 8o). — Time for the Superbend to go from 99% to 80% of its field after a quench is > 0.5 seconds. • Plenty of time to halt the next injection pulse Conclusion – Not an issue
Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004 23

•

•

Changes to Radiation Safety System (RSS)

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Summary - e- down beamline
Summary: cannot inject e- down b/l assuming: 1. Redundant interlock on stored current (≥10 mA). 2. Redundant interlock on energy match (< 10 %). Future Plans: • Analyses assume 2.1 worst case. Need to prove this with more simulations • Begun forward tracking studies. • Tracking study results are convincing but not always intuitive. Need independent study to verify results.

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Top-off Radiation Issues/challenges
1. Injected Beam – PSS now open • Injected e- go down beamline? • Injected e- strike the storage ring vacuum chamber near the beamlines inside ring? 2. Stored Beam - (1440 mA/shft)/(200 mA/shft) ~ 10X 3. Rf Trips - average I from 250 to 500 mA, so ~ 2X First is unique to top-off. Second and third are important, known, but not unique.
Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Increased Bremsstrahlung from Injected Electrons

• Difficult to calculate. Requesting permission from DOE for PSS-open tests. Measure under abnormal injection conditions. • Horizontal scrapers in BTS line.
—Booster area well shielded —Limit/localize lost injected particles

• Vertical scrapers (next section) in the Storage Ring • Consider interlocking beamline ion chambers. • All beamline gas bremsstrahlung Pb shields (ID and BM) are 10‖ thick.

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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BTS Injection Scrapers

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Stored Beam Losses and rf Trips
Stored Beam - (1440 mA/shft)/(200 mA/shft) ~ 10X Rf Trips - average I from 250 to 500 mA, so ~ 2X Approach: • Simulate particle loss when rf trips. Predict where losses occur. Compare w/ reality/history. • Investigate losses at ―Jackson Holes‖ as a function of fixed aperture heights. • Consider installation of ―semi-fixed‖ scrapers at optimum JH locations. • Locally shield JH scrapers.
Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Modified Henderson Plug in Jackson Hole

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Stored Beam Losses & rf Trips
Simulation Studies (H. Nishimura): Can e- beam losses be localized/controlled?
• Lattice errors are assumed to produce realistic orbit errors. • While the beam is circulating normally, the RF tripped instantly. • The beam keeps circulating by loosing energy due to synchrotron radiation.

— The 6-dim routine is used to calculate the radiation loss properly.
— The interactions between the beam and the unpowered cavities are neglected.

• During the tracking, apertures are checked at each JH location and also at both ends of each straight section chamber. • This process was repeated for 100 random seeds.
Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Tracking with apertures
Beam gets lost vertically on the narrow gap chamber

4

8

12

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

34

Beam Dump at SR02 JH6/SR03 JH1
120 100 80
Loss [%]

60 40 20 0 4 5 6 7 8 9 10 11 12 13 Half Gap at 2-6 and 3-1

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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JH Scrapers Sector 1

JH Scrapers Sector 3

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Jackson Hole Scraper

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Storage Ring and rf Trip Losses
Summary • JH scrapers can be used to localize losses. • Complete simulations to determine optimum JH scraper locations. Determine effect on lifetime. • Consider scraper design where position can be ―changed‖ but then ―fixed‖. • Provide local shielding close to JH scrapers. • If all else fails…

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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… add local shielding.

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Future Plans
• Monitor radiation when injecting with PSS opened on Beamline 4.0 (Early 2005). • Install BTS and JH scrapers. Show they can be used to localize losses (Early 2005). • Radiation safety review (Mid 2005) • Installation of RSS interlock systems (Before top-off operations)

Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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Berkeley Lab
Top Off CDR Review, Nov 22-23, 2004

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