Transcript Commissioning, Operations and Availability Tom Himel SLAC Co-conspirators Eckhard Elsen Tom Himel Nobuhirio Terunuma Janice Nelson Marc Ross Sebastian Schaetzel Alberto Fasso Syuichi Ban Toshiya Sanami G.

Commissioning, Operations and
Availability
Tom Himel
SLAC
Co-conspirators
Eckhard Elsen
Tom Himel
Nobuhirio Terunuma
Janice Nelson
Marc Ross
Sebastian Schaetzel
Alberto Fasso
Syuichi Ban
Toshiya Sanami
G. Xia
F. Poirier
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Contents
What we do and interface to other
groups (who costs what)
Availability simulation improvements,
new results
Radiation rules and calculations
Items to be discussed with other groups
List of dumps
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Our Responsibilities and Interfaces
Our main job is to make sure the ILC can be commissioned and run
efficiently
Himel is the contact person for our group to all the other groups.
For our actual work, each subject is headed by the person in bold mainly
with resources from their region.
Availability: Himel, Elsen – Specify subsystem and device availability (mostly
in BCD already). Advise on design issues that might effect availability.
Commissioning: Elsen – Work with CFS on construction and commissioning
schedule and specify temporary dumps, shield walls, bypass beam lines
needed for commissioning
MPS and fault recovery: Elsen, Himel – Do high level MPS design including
fault analysis and the effects of the faults. Detailed design and costing will be
done by the controls group for the electronics and the area groups for the
kickers and dumps.
PPS: Teranuma, Himel – Shielding design and radiation calculations.
Electronics costs will be done by the controls group. Shielding and beam
stoppers will be costed by the area groups.
Tuning: Elsen – Check that each area has enough tuning and diagnostics built
in and check how they all work together.
Transportation, people and supply depots: TBD
Number and location of dumps: Himel – Dumps are used for running, tuning,
MPS, and PPS. Coordinate decisions on their location and power handling.
Summary: Our job is to make other groups spend money to make ILC operable
Improvements to Availsim
DR in separate tunnel from linacs (but still dogbone
magnet count)
Bunch Compressors now in DR region, not linac
Keep-alive source is on e+ side
Broken global system (site power, global controls) 
keep-alive broken
E+ transport line is in both linacs and both BDS’s
Numbers of components not updated yet. Will wait until
number of magnets and power supplies settle down (2
months?)
Randomized recovery times
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PEP-II recovery vs downtime
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HERA data
Recovery times for short downtimes
Recovery times for medium downtimes
Use exponential distribution to simulate
Average Recovery Time vs
Average Downtime
Keep assumption of recovery proportional to time
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Should keep-alive source be on e- side?
Pros
Might be able to share some of the main
e+ source accelerator
Cons
Availsim says Int Lum decreases 0.1% negligible.
e- source for e+ DR cannot share some of
the keep-alive source accelerator
Can’t be used for early commissioning
Conclusion: a wash.
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Should all 3 DR be in one tunnel?
Pros
Less tunneling cost
Rings would probably be near IPs and central site,
so transport time would be less when repairs are
needed
Cons
When access needed to one ring, no beam can be
in other. Availsim says Int Lum decreases 0.7%
3 rings in 1 tunnel could make maintenance
difficult if not very carefully engineered.
Prefer 2 separate tunnels, but all in 1 not a
killer.
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Should ability to have people in
linac and beam in DR be dropped?
Pros
Save money on stoppers and shield walls. Would
still need same dumps for tune-up.
Would save a lot of debate about how to make it
safe for people.
Cons
Availsim says Int Lum will drop by 1.3% if both
DR’s, linacs, and BDS’s are a single PPS zone
instead of separate.
Might restrict DR commissioning during linac
construction.
Conclusion: Keep the separate PPS zones.
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Radiation Safety Rules
Complex and different at different labs. Here list
amount a lab worker can be exposed to.
SLAC: Normal operation < .005 mSv/hr or 10
mSv/yr; misteering < 4 mSv/hr; worst failure (18 MW
loss) < 250 mSv/hr and < 0.1 mSv/incident (that is a
1.5 second loss at full power) (shield to < 0.014
mSv/hr/kW-loss)
DESY: Average operation < 1.5 mSv/yr. Assume
losses dominated by misteering causing 100 W/m
loss for 100 hours/yr (shield to < 0.03 mSv/hr/kWloss) (assuming 5 m of line loss is equiv to point loss)
KEK: Average operation < 2 mSv/yr (what loss to assume
not known)
Conclusion: Rules differ, but limits similar. Will use
tightest: shield to < 0.014 mSv/hr/kW-loss.
Tunnel separation and Rad calcs
Sanami did full MARS simulation
Tunnels separated by 0.3 m concrete, then 4.7 m
soil, then 0.3 m concrete
No penetrations yet
Result: 0.0016 mSV/hr/kW point loss
Multiplying by 4 for conservative error estimate
gives 0.0064 which is < 0.014. OK
Tunnel Rad calc w/ FLUKA by Fasso
• Uses full tunnel geometry
• Loss is 1 m upstream of 35 cm diameter
penetration
• Support tunnel below 3.5 m has 0.003
mSv/hr/kW which is < 0.014 OK
• Conclusion: < 5 m between tunnels is
definitely not OK. 5 m is OK, if willing to
fence off area near penetrations.
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Radition vs. Tunnel Separation
Old NLC calc shows gain factor 10 per 75 cm
separation
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Getting people between tunnels
Direct connection with maze NOT OK. Too much
radiation.
Use more elaborate path like below. Details  CFS
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To be discussed with other groups
# magnets and PS vary widely
In e+ transport we had 310 quads. In last month
design has 8k3k1k
12 m long bends in BDS may become 4 3 m bends.
We’ll wait until numbers settled for costing and get
new counts.
Where are PS, electronics for DR and BDS?
We have assumed NOT in accel tunnel.
Need HA magnet/PS R&D desperately
There is a lot of HA controls activity starting, less on
PS and none on magnets.
Need HA magnet and magnet+PS+interlock+cable
HA R&D desperately. Long-lead time as need to
build and test many, preferably in a real accelerator
Dumps
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MPS
Very little done since BCD
Starting failure analysis + simulation in
linac. With various failure modes
(phasing, magnet shorts, magnet
settings) what will beam hit and will it
destroy it.
Answers may determine if pilot bunch
and 1 dump/km in linac (ACD) needed.
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Dumps – the reasons
Some needed to allow fast recovery from probable
frequent MPS trips
Full power dumps needed downstream of systems with
significant beam heating. Allows them to stay warm during
an MPS trip and speeds the recovery.
Others needed to allow a system to be tuned without
potentially damaging beam going through
downstream systems
Only need to take ~100 bunches per train at 5 Hz. Enough
for intra-train feedback and LLRF.
Above assumes we handle beam loading compensation
OK.
Some need added redundant stoppers and shielding
walls to allow beam in one region with people in
another.
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Dumps – the LIST
We have made a draft list of all the
dumps and the reason each is needed
Will be distributed shortly
Some dumps may be controversial as
high power dumps are expensive
Need a decision making process:
We (operations) dictate?
Negotiate with each region?
Exec board mediates?
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