An expansion tank high level warning has been added to the T1/T2 control system under Work Request #4011.  The purpose for this new warning is to alert staff of an unexpected water increase in the unlikely scenario that a leak develops in the heat exchanger between the two fluids and CuALCW on the secondary side enters the target water system.  The new thresholds for high level warn, low level warn, and low level trip have been set at 40cm, 30cm, and 25cm respectively.  The nominal water level is 35cm.  All thresholds were tested by adding water to the tank, or removing it.  All responded as expected.

 The following changes were made to the T1/T2 PLC control system:

- De-glitching system investigated and Tony discovered that it was programmed incorrectly:  the de-glitch time was observed only when a PV changed from bad state to good, not the opposite (meaning there was actually no de-glitching in place since system start-up in 2016!).  This was reversed and the following de-glitch times were programmed:  100ms for trip thresholds except 300ms for flow meter trips, and 2s de-glitch on all warning thresholds.  The new system was tested with the PLC in simulation mode and seems to be working correctly.  This should eliminate or significantly reduce nuisance warnings and trips from the system.

- PLC system code was modified so that the target version displays '???' when no target is installed instead of defaulting to 'MK1'  (all target positions registered as 'plugged' with no target installed, so there was no danger to the system, but this was still confusing to operators)

A strategy for alignment of the T2 protect monitor, T2 target, and T2 Collimator A was discussed today and decided upon by Yuri Bylinski, Isaac Earle, Yi-Nong Rao, and Roman Ruegg.  The purpose of the adjustment is to try to reduce the amount of beam lost as it passes through the T2 area (presumably being blocked by the collimator because it is not possible to steer the beam through all three devices in their current configuration).  Keeping in mind that changing the elevation of Collimator A would be prohibitively time consuming it was decided that the protect monitor and target both be adjusted upwards 3.0mm compared to where they were during the 2016 running period.  This will result in the following elevations (all w.r.t. the T2 target flange).  The T2 profile monitor elevation will also be adjusted to match the target elevation.  

T2 Protect Monitor:  1833.5mm (1833.2mm from protect monitor flange)

T2 Target: 1836.5mm 

T2 Collimator A:  1834.7mm  (1834.5mm from collimator flange;  This is the current collimator elevation, measurement taken by Tom Lyth in Feb 2009)

These values are similar to what were used in 2009 during which time TNF neutron flux rates were acceptable (>800), and centered beam spots were achieved.  During the 2016 running period the beam spot on target was also roughly centered.  At both times the target was approximately 3mm lower than the protect which seems to indicate the beam is travelling at a downwards angle, possibly not correctable with available tuning.  This is a departure from the strategy in the last few years when the target and protect monitor were adjusted downwards to bring them closer to the beam plane (they had risen due to movement of the T2 monolith).  This is now thought to have been a mistake because it made it difficult to steer beam through the collimator.

Beam will be started with T2 in Position 2 (new target, never seen beam), then after a few days the target assembly will be moved to the hot cell to check the beam spot to confirm alignment and make changes if the strategy needs adjusting.

A PDF copy of Yi-Nong's summary is also attached.

The following work was performed on the T2-MK2 target assembly and the T2 Protect assembly for maintenance purposes and to implement the alignment strategy detailed in E-Log #218:

March 30 (T2-MK2 target in hot cell):
- Profile monitor actuation checked:  moved in and out smoothly, fully in at ~25psi
- Ran through all target positions, motion smooth, micro-switches all ok, potentiometer value unsteady when moving between position 0-1, steady when stopped, no issues form positions 2-5 (this was also observed last shutdown and there were no issues with ladder moves in the 2016 running period using EPICS)
- Water system pumped out with cold trap for 2 hours (previously was purged with clean water, then air overnight)
- Leak check performed: 10 minutes to reach 5.0E-3 Torr TP pressure, 25 minutes to reach 1.0E-3 Torr; 3psi helium supply applied in 0.5s bursts;  No response at all target locations and all four aluminum delta seal locations.  At base of bellows on left side (when facing ladder) quick response up to 0.6E-8atm.cc/s, quick recovery to baseline (<10s); At base of bellows on right side (when facing ladder) quick response up to 1.2E-8atm.cc/s, quick recovery to baseline (<10s).  These small helium leaks were known (see E-Log #95) and have not caused issue in multiple years of running.
 

April 5:
- Position 1 and 2 potentiometer ratio changed to achieve new target alignment, look-up tables updated in PLC code (see E-Log #218, and attached new elevation measurements)
- Position 1 and 2 micro-switches adjusted to be centered at new positions
- Profile monitor inspected: no broken wires, but some not quite straight or parallel with others, also some wire insulation blackened.  Scott Kellogg recommended installing new profile cassette
- Old profile cassette removed in hot cell and new one installed
- Profile monitor elevation adjusted (see attached new elevation measurements)
 

April 6:
- Electrical check on profile monitor performed at HC by Dave Cameron: deemed OK
- T2-MK2 moved from the hot cell to the beam line (~200mSv/hr at 0.5m)
- T2 protect monitor moved from beam line to hot cell (~16mSv/hr at 0.5m)
 

April 7:
- Elevation of protect monitor measured to confirm old measurement: within 0.1mm
- Old protect monitor cassette removed
- New cassette supplied pre-adjusted by Scott Kellogg
- New cassette installed in HC, elevation measured on entrance side: 1832.8mm (intended elevation was 1833.2mm, from E-Log #218)
- Protect monitor electronics checked by Shengli Liu and Dave Cameron at the hot cell: all OK
 

April 10:
- T2 profile monitor cable plugged in which caused unexpected jump in vacuum: 20mTorr - 180mTorr
- Large nut at top of feed-through connector tightened and vacuum returned to baseline
- T2 target position 1 and 2 potentiometer values tested from EPICS system to confirm PLC look-up table changes ok
 

April 11:
- T2 Protect assembly returned to beamline (12mSv/hr at 0.5m).  T2 monolith position was monitored by Beamlines Group with their laser tracker during the move.  A maximum of 0.2mm movement was measured which is attributable to noise.
- Air amplifier started, leak found from one of the M20BB cylinders;  went away after reset of BB control system, BB exercised several times and leak could not be reproduced (no change to BL vacuum)
- T2 profile monitor tuned for slower actuation, smooth movement confirmed and no change to beamline vacuum (also done for T1 profile monitor)
- Electrical check on T2 protect monitor performed by Dave Cameron and Shengli Liu from racks on mezannine: all OK
- Electrical check on T2 profile monitor performed by Dave Cameron and Shengli Liu from racks on mezannine: initially very low signal, they discovered a previously unknown large resistor which was bypassed for the test:  approximately 1/2 of signals show response to HV blip, deemed OK to restore shielding
- Target info sheet and updated elevations measurements delivered to Operations (elevations sheet attached)

Note: the T1 target (T1-MK2) was not removed from the beamline this shutdown, so new elevation measurements have not been submitted and T1 profile and protect monitor checks have not been performed

 On May 5th the T2-MK2 target was moved to the hot cell for the purpose of checking the beam spot on the Position 2 beryllium target to confirm the results of the T2 area realignment detailed in E-logs #218 and #220.  In preparation beam was put on this target overnight for approximately 1.5hrs at 10uA and 4 hours at 50uA (previously had not seen beam).  Also, there had been issues with the T2 profile monitor over the last couple days, so inspection and repeat of electrical check in the hot cell was planned.  The field in the T2 monolith work area was up to 1.3mSv/hr, and a maximum field of 230mSv/hr was measured 0.5m from the target during removal.

Unfortunately no beam spot was visible on either the entrance or exit windows at Position 2  (a longer exposure will be required next time a beam spot is to be inspected).  Detailed photos were taken, one of each side attached.  It was noticed that the T2 profile monitor cassette had become dislodged within its housing (it was sitting approximately 1" from the fully installed position - photo attached).  It is suspected that this happened when the target assembly was in the beamline - the first time the profile monitor was exercised back in April it moved quite quickly which may have caused the cassette to come loose (it is only held in with friction of the 9-pin connectors and the fit of the cassette body in the housing).  It was re-inserted in the hot cell and an electrical check was performed by Shengli: all good.  After the target was returned to the beam line the electrical check was repeated while the monitor was actuated in and out: once again all good, and the movement of the monitor was slow and smooth (video taken)

Prior to this job new cameras were installed in the hot cell opening aimed at the support ring hole (one aimed north, the other east).  This proved to be a very useful upgrade and made the installation process significantly easier and smoother.  Two cameras were also used during target installation at the monolith (only 1 was used in the past).  Having a second camera at a different angle made alignment easier (reducing time and dose), and should be adopted for future target moves.

Vacuum pumpdown was normal, the cooling system was restarted without change to the vacuum, and operators were able to use the T2 profile monitor during beam ramp-up overnight.

Dose for this job:  Isaac 0.17mSv, Keith 0.06, Ron 0.06

test 2

Six 5 gallon pails were transferred this morning from a temporary storage bunker in the Warm Cell to the Rad Waste Pit for long term storage.  The pails contain various BL1A active waste from the East Hot Cell including dozens of irradiated beryllium and graphite targets.  The field from the pails ranged from 0.1 to 9mSv/hr at 0.5m.  The work was performed according to the clean-out procedure (Document-142965).  Photographs and records of the pail contents, field, weight, etc have been uploaded to Docushare Collection #20185 and hard paper copies were given to RPG.

All remaining waste in the east hot cell is too large to fit into 5 gallon pails, so it must be packaged in a 55 gallon drum.  Some long items will need to be cut in the cell before hand.

The field on the hot cell roof is now less than 5uSv/hr in working areas, and a maximum of 55uSv/hr at 0.5m above the east hot cell opening.  The field was previously > 50uSv/hr in some working areas, and > 200uSv/hr above the opening.

Before and after photos of the hot cell interior are included below:

The following work was completed on both the T1 and T2 target alignment frames

• One of the short taper pins on the top of the frame was swapped for a longer version to simplify flask alignment to the frame (now one pin can be aligned at a time instead of both concurrently)
• Three permanently mounted cameras installed to view east/west alignment, north/south alignment, as well as hook, latch, and door position
• LED strip lights installed on the bottom of the frame for better illumination during alignment of target devices
• All video and power signals routed through a single connector (9-pin CPC) for ease of use
• Frame painted with blue Rustoleum metal paint
• Hole positions, alignment orientation, camera position, etc labeled on frame

 The M9 service stand floor plate (TB23351) was installed in the M9 pit yesterday.  Prior to installation all 5 threaded inserts were tested using a 1/2"-13 stud tool on an RH pole.  The west most hole (shown in red below) had damaged threads and the stud could only be threaded in 2 turns.  All other locations (shown in green) had usable threads with 6-8 full turns possible with the stud tool.  The plate was installed using RH floor plate bolts (TB23382) at all four locations with viable threads.  The bolts were torqued to 30 ft*lbs which on a bench test was shown to fully compress the belleville washer.  The standard torque spec for 1/2"-13 stainless bolts (43 ft*lbs) was not used to allow easier disassembly in the future.

 The M9 Q1Q2 "foot" plate (TB23363) has been installed over the floor plate.  A nominal gap between the plates of 1/2" was set before lowering the plate, it was then leveled using the three adjustment bolts resulting in a larger gap.  After leveling, the plate was lifted to remove the spirit levels and lock the position of the leveling bolts.  The plate was then re-lowered and the tiedown bolt assemblies (TB23383) were installed using 50ft*lbf of torque (about the maximum practical amount with standard 20' pole tools)

 The 10-pin thermal switch wire, 2-pin steering wire for Q2, and a 1/4" copper tube for remote helium leak check were installed through the service chase with the power cables and connected to the M9 service stand.  Approximately 10m of extra cable (2-pin and 10-pin) was coiled and left in the cooler section of the service chase after the first sharp bend.  The cables and the tubing are currently run as far as the vertical cable tray "waterfall" located near the M11 area.

 Laser tracker scan data from 2017 and 2019 attached as a backup.  Original files from Beamlines Group who also keep copies on \\trwindata\experimental support\alignment\T2-M9_data

The Q1Q2 water header (TB23481) was mounted this morning as per installation drawing TB23400.

Heat shrink tubing was applied to the B1 power cables (two positive, two negative) over the length of cable in the highest field which was showing some signs of radiation damage on the insulation.  The tubing used was McMaster-Carr PN 75665K932 (Clear PTFE, 4:1 shrink ratio, 1.0" ID before shrinking), as recommended by Syd Kreitzman.  Each piece of tubing is 4' long, and two were used per cable.  The first one was shrunk along its full length, then the second piece was only shrunk where it overlaps the first and the remainder was left loose.  This was done to minimize time required in the high dose area.

Hand-stacked concrete bricks were removed from the location where the new piping will run to the water header.  This is scheduled to take place between July 6-8

 The M9 Q1Q2 magnet assembly lift beam has been installed according to drawing TB23401.  The side-to-side as well as beam-axis direction adjustment features were tuned so that the assembly is level when lifted.

Aug 5, 2020 update:  All fasteners on the lift beam assembly have been torqued according to the specification on drawing TB23401

The diagram below shows the wiring for the two connectors on the service stand (the wires running from the stand to the power supplies.  (see TB23400 for details)

 Mike Vogel reported that alignment of the Q1Q2 assembly w.r.t. the T2 and B1 flanges was completed on July 7.  This was performed in the test stand with the flange positions set to the measurements taken in the 2019 shutdown.  Alignment to the theoretical location was achieved within 0.1mm.

The axis of the Q1 and Q2 magnets were aligned to each other previously within similar accuracy.

A trial run of remote removal of the UCN target was performed using the shielded target cask (TTA0335) developed in 2020.  The work took place between Feb 9 - 17 under work permit C2021-02-09-1.

The procedure in work instruction Document-187117 R1 was followed. Draining and purging of the water system as well as venting of helium from the target crypt was performed by Tony Hessels.  The remainder of the procedure was carried out by Keith Ng, Maico Dalla Valle, and Isaac Earle.  A maximum field of 1.7mSv/hr was measured at 0.5m from the bare target;  This is higher than the approximate 500uSv/hr field that was expected, however dose incurred during the work was minimal (Isaac: 0.05mSv, Maico: 0.03mSv, Keith: 0.03mSv).

The cask aligned well to the target arm and no modifications to the cask or UCN hardware were required to carry out the procedure.  A few updates will be required to the work instruction document based on discoveries made during the procedure; notably: 

• Cask to be installed on the west side of where the water tubing connections for the crypt flange are located;  As a result the cask lid will be installed after the cask base (with target forearm inside) is removed from the rails
• Shims are not required under blocks TTA0550 and TTA0555 in order to clear the top of the cask (the concrete and steel supports for these blocks are higher than in the UCN area shielding model)
• In addition to the six 3/8"-16 bolts for the water manifold, two shoulders screws (one on each side of the manifold) must also be removed to allow the two halves to separate

The work instruction document will be updated to include the changes above, as well as other minor updates and extra figures. 

After testing, the target forearm was reinstalled and all connections re-made.  Leak checking of the water connections and crypt flange as well as testing of the target thermocouple signals is to be arranged by the UCN Group.  The cask has been stored on top of concrete shielding on the B2 level north-east of the UCN experimental area.

Various photos taken during the procedure are attached.

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