On Monday February 4TH  the Service Bridge was being lifted into  the Cyclotron with the Carrier. It was noticed that one of the two Hydraulic Jacks was leaking. All work stopped and the Service Bridge and Carrier were moved to the Remote Handling B2 level for repair. The Service Bridge and Carrier were separated and the Hydraulic Jacks were inspected. It was noticed that both Hydraulic Jacks were leaking. Two overhaul kits were ordered. Two other Hydraulic Jacks were found and replaced. Work continued in the Cyclotron with the Bridge and Carrier. The two  Leaking Hydraulic Jacks were overhauled. Once most of the work in the Cyclotron was done and there was time that the Service Bridge and Carrier were out of the Cyclotron and not in use the two overhauled Hydraulic Jacks  would be replaced. They were tested without the Service Bridge and then with the Service Bridge. There were no leaks and all operation was back to normal.   

Attached is a scan of a handwritten record from 1994 showing yoke-to-upper-structure gap measurements from 1994, both L and R sides, with tank under vacuum and vented.

The measurements appear to be made with a 0.25" shim and 0.01" pieces of shim stock as they are only in increments of 10 thou.

The 1994 gap appears to vary from 0.25" to 0.33" (80 thou max variation) under vacuum, and from 0.29" to 0.33" vented (40 thou max variation).

Our 2013 measurements, made with a 0.25" piece of stock and a feeler gauge, varied from 0.265" at Station 1 to 0.445" at Station 11, (180 thou max variation, see Jan 28 e-log).

I have not yet found any other records of this measurement but I will keep searching.  The gaps may have varied by as much as 180 thou for many years.

I recommend checking the clearance at all stations and jogging individual stations such that the gaps are within a 40 thou band prior to the next lift.

Attached is a compiled record showing the years of service of the jacks, upper bearing, and gear reducers, prepared by Grant Minor on December 17 2012.

Due to concerns raised regarding the state of the lubrication of the power screws at Station 9, the lubrication was visually inspected by me and Ron Kuramoto on February 4th.

Photos are attached.

The power screws for these stations were serviced and re-lubricated on the following dates:

Station 9 - 1996

Station 10 - 2001

Station 11 - 1997

Station 6 - 2011

There did not appear to be any major visual differences in the lubrication between any of these stations.  The grease at Station 9 appeared to coat the power screw uniformly through its range of travel, and there were no major signs of drying, hardening, or separation of the constituents relative to the other stations inspected.

There is a slight apparent difference in the opacity of the grease between Station 9 and Station 6 in the photos attached, but this may be due to the lighting and camera flash at the angle taken.

There did not appear to be any flecks of metal, contaminants, or other signs of abnormal wear in the grease.

The mechanical properties of the grease at Station 9 vs. virgin grease would have to be assessed by a tribologist in a laboratory setting from samples.

Samples of the grease were not collected at this time, but could possibly be collected in the future when Station 9 is removed for service.

The hydraulic cylinder on the West side of the service bridge (used to raise the bridge for insertion into the Cyclotron) failed this morning, leaking oil in the vault tunnel.  Most likely this was due to a failed seal or gasket.

Maico Dalla Valle has removed both the East and West cylinders for refurbishment and is pursuing repair kits from Hyseco.

The purple coloured cylinder on the East side has been slowly leaking oil for some time.  A gasket in the West cylinder (yellow) seems to have failed and a broken piece of the gasket was removed during the disassembly, shown in the photo "Hydraulic Cylinder Gasket 4 Feb 2013 008.jpg" attached.

Cylinder model number is ENERPAC RC-254.

http://www.hyseco.com/

Dan Louie's e-mail comments from 30 Jan 2013 are attached.

- Grant

Lid-up was first attempted yesterday (Jan 28th) by Dan Louie, Arthur Leung, and Maico Dalla Valle.  They experienced problems with Station 9 continually tripping the system and were not successful.

This morning again there were problems raising the lid above ~1 inch due to tripping at station 9.  It was observed that the mechanical counter at Station 9 was increasing about 5 to 6 times faster than the counters at the other stations.  There may be a mechanical problem with the gear reduction for this counter.  However, the mechanical counter is just a readout and does not control any aspect of the lid up.   Comparisons between stations 9 and 10 at the 1 inch trip point are shown below.  Station 10 is representative of the other stations within about 100 counts. 

The lid was lowered fully and the gap between the yoke and the upper structure primary beams was measured by Maico at one spot per station with 1/4" stock and feeler gauges (see attached reference photo from 2012).

Not much could be concluded from the measurements.  The control system is supposed to keep the jacks parallel within about 50 thou, however Stations 1 and 11 appeared to be out by 180 thou.  It is difficult to say without further study whether this larger discrepancy is due to overshoot at each station after the lower limit switches are reached.

Grant Minor, Dan, Maico, and Arthur met in the Main Control Room at around 1:30pm to assess.  Dan commented that Station 9 was continually lagging in the system and causing the ~1 inch trip.   The decision was made to drive the whole system to the ~1inch trip point and then jog Station 9 manually to bring it back into the "go" band of tolerance, and continue on this way until the "sticky" portion of travel was overcome.  In Grant's opinion, the transmission system at each station (motor, reducers, jacks, and upper bearing) sits dormant in one position for a full year each year and settles in a single position.  Some asymmetry in the static and dynamic friction from station to station is expected after such a long idle period.  Additionally, the lubrication at station 9 has not been serviced since 1996 (18 years).  Grant also felt that jogging the system in small increments to bring it back into the tolerance band should not damage the jacks, motors, or reducers provided they were carefully monitored for abnormal noises or overheating.

The sequence of events following the 1:30pm meeting is outlined below:

- The system tripped as expected around 1 inch.

- Station 9 was jogged upwards 20 thou, measured with the dial indicator.  Station 9 counter increased from 9255 to 9429.

- The entire system was run upwards by about another inch with several more trips, some from Station 9 and some from other stations.  Dan reset the system after each trip.

- At around 2 inches, Station 9 was jogged again.  Maico reset the dial indicator and attempted to jog manually but the dial did not move.  This might have been due to the lag at Station 9 creating some amount of backlash before the load was taken again.  He reset the dial again and this time measured a jog of 25 thou.  Dan asked us to back off by 20 thou, then he reset the system and we continued to raise.

- The system was raised to about 3" in small increments with several more trips, each time reset by Dan.  Station 9 was jogged 3 more times during this period by 10 thou each time, at approx. counter readings 16 362, 16 802, and 17 134.

- The system then ran properly for quite some time and tripped at around 6 inches.  We stopped to inspect the tank seal, which was OK.

- The system was reset by Dan and run again to about 10 inches, at which point station 1 tripped.  Station 9 counter read 60 775, Station 11 counter read 10 829 (again a factor of 6 discrepancy).

- Dan requested a jog of 10 thou at Station 1, and then we continued to run.  The system ran with only a couple of trips up to about 1 foot from the upper limit.

- At around 1 foot from the upper limit, Station 7 started to cause tripping.  It was jogged 10 thou and we continued all the way to the upper limit.

(Total travel is approximately 48 inches or 4 feet).

During the course of the work, it was observed that the motor at station 9 was getting hot early (around 2 to 3 inches of travel), but the motors at other stations (e.g. Station 11, Station 1) reached about the same temperature to touch after the system was running properly.

Report by Grant Minor, P.Eng.

It was observed during the last time the Cyclotron service bridge was used the orbit drive chain had a lot of slack. The drive motor had to be shimmed to tighten the slack in the chain. 

Shut down work for 2012.Replaced serviced Jacking Station #6. Tapered alignment pins were damaged. They were skimmed and checked and installed. Station #4 was removed and the spare Station was put in its place.Station # 4 Upper Bearing was inspected and serviced.Station #4 had a problem with the Jack on the right side.The coupling hub than joins the Jack to the High Field was installed backwards.(Not sure how long the hub has been like this maybe 15-20 years?). The coupling and hub had to be cut/split apart to get them off of the Jacks shaft. A new coupling and hub was machined and installed. Anew shaft seal was installed next to the new coupling hub. All the old grease was removed from the Jack. The Jack was inspected and then new grease was replaced. The left Jack was also serviced. It was taken apart and the old grease was removed. The Jack was inspected. The shaft seal on the other side of the coupling hub was replaced. New grease was replaced. The two High Fields had the oil drained. They were inspected and new oil was replaced. #4 Stations motor has four mounting bolt holes and two tapered pin holes for alignment. The one tapered pin hole in the front right side of the motor had a small hairline crack. The paint was removed in the area where the crack was so it could be welded.(The motor base is made of Cast Iron). The crack was  welded with 309L SS welding rod. After welding the tapered pin hole was checked with the tapered pin.(It was OK). The #4 motor was bolted to the service area work bench. An Electrician hooked the motor up for testing. The motor was greased  and then  it was  started.  It ran nice and smooth.           

All control to the video trolley was lost during remote photographing of components in the cyclotron. The control system and cameras on the trolley were still operational leading to the suspicion that a power cable was broken either on the trolley or the bridge festooning. Two trips into the tank were made to evaluate the problem and attempt to push the trolley out of the tank. Pushing the trolley only managed to move the trolley a few feet before jamming. A lift mechanism was used to raise the drive wheel without any success. This device was modified and used successfully to remove trolley completely from the tank.

Today Remote Handling staff (Maico Dalla Valle, Travis Cave) used the Remote Handling 2C probe removal trolley to remove the probe assembly from inside the Cyclotron.  This is a regular yearly MRO task that is done every shutdown.

This task involves lining up the 2C trolley on the service bridge with the 2C probe assembly remotely with cameras, using a set of alignment markings on the trolley and probe assembly.  Once the trolley is lined up with the probe assembly, a set of solenoids are fired to disengage a corresponding set of four QDLs (quick disconnect latches) at different locations on the probe assembly.  A complete procedure is documented by Remote Handling staff.

The four QDLs are actuated by a set of four solenoid actuators on the 2C removal trolley, numbered 3, 4, 5, and 8.

Traditionally in the past, the QDL actuated by solenoid 8 has  jammed and does not automatically disengage when hit with the solenoid actuator.  A member of Probes or Remote Handling has had to suit up with a respirator, run into the Cyclotron tank, and tap this QDL by hand to free it from it's jammed state.  This has been done every year for quite some time, as long as Don Jackson can remember (around 30 years)!

However, today, Remote Handling staff (Travis and Maico) were able to disengage all four QDLs remotely using the solenoid actuators on the trolley!

A few things were done differently this year compared to previous years, which may have contributed to this success:

a.  The centre post bearing on the service bridge was disassembled, cleaned, and lubricated (see previous e-log from this shutdown)

b.  The "AXIAL A" alignment tab on the 2C removal trolley was intentionally misaligned with the felt pen markings on the 2C assembly (see attached picture that points out this "gap").

c.   The solenoids were fired in the following order: 8 (no success on disengagement), 5 (success), 4 (success), 3 (success), then 8 again (success).

After all four QDLs were disengaged, and the probe assembly was lowered away from its fixture points, it was observed that the assembly moved slightly laterally, indicating a slight stress or misalignment between all four QDL pins and their corresponding receptacles in the Cyclotron tank. The "gap" labelled in the attached picture, shrunk a small amount after this lateral movement.

Don Jackson remarked that in his entire tenure here, he had never witnessed successful remote disengagement of all four QDLs!  This is quite a positive result, as it lowers the expected dose and time required to remove the 2C probe assembly.  This approach to the task should be repeated next year and video documented (unfortunately we were not video recording the successful attempt this year).

Cheers,

Grant Minor, Remote Handling

Repair of Orbit Limit Switch Plastic Belt

During the fall of 2011, Remote Handling discovered that a plastic toothed belt had stripped in the Cyclotron Bridge orbit limit switch mechanism.  This toothed belt is supposed to wrap around the stationary outer race/chassis of the center-post bearing on the Cyclotron service bridge.  The belt meshes with a smaller spur gear, which connects through a gear reduction system to a potentiometer and a limit readout.  The purpose of this limit switch is to prevent multiple continuous orbits of the bridge in one direction around the Cyclotron, which would twist and stress the trolley electrical wires.  Below is a picture showing the stripped belt condition as of Sept 23, 2011 (photo by Travis Cave).

During November 2011, Maico Dalla Valle and Travis went through the drawings of the service bridge assembly and ordered a replacement belt from the original manufacturer (still in business).  Maico removed the central bearing assembly, disassembled the bearing, replaced the belt, re-lubricated the bearing, and reassembled the unit into the service bridge.  The belt that was installed by Maico was installed with one less link / tooth than the previous belt, to obtain a tighter fit, so that fewer shims had to be used to fit it snugly against the outer race / chassis.  After assembly back into the service bridge, Maico commented that a much better mesh was achieved with the pinion. and the system was much easier to turn by hand.  This was likely due to re-lubrication of the centre post bearing and and improved  mesh / fit of the pinion with the belt.  A photo of the serviced assembly with the new belt is shown below:

Orbit Counter System - Operational Improvement (mid-Jan to Feb 7 2012)

During the 2011 winter shutdown, there had been some observations of inaccuracy in the orbit counter mechanism used for the automated radiation survey of the Cyclotron.  These observations were made by both Remote Handling and RPG staff.  The purpose of this orbit counter is to provide an angular position measurement of the service bridge relative to a known reference point in the Cyclotron vault, within a certain degree of accuracy and precision.  It appeared that the reading coming from the counter wheel that makes contact with the outer sector surfaces and follows the service bridge along it's orbit was skipping at various suspect locations around the perimeter of the Cyclotron. This skip, at it's worst, was deemed to be sizable enough to invalidate the automated survey of the tank.  Several e-mails and reports were generated by multiple parties in Remote Handling and RPG about the problem (attached).  The problem was not repeatable each time.  A photo of the counter wheel riding along the perimeter sector surfaces is shown below (taken with RH outrigger camera):

Various theories on the problem and potential solutions were discussed, including:

- Warped aluminum perimeter sectors protruding a small amount into the path of the orbit wheel, causing the wheel to skip as it passes over these bumps (see photos below)

- Insufficient traction between the counter wheel and the perimeter sector surfaces that the wheel rides on.

However, after the center post bearing had been serviced by Remote Handling, and during the routine service bridge work for the 2012 shutdown (copper blockers, shadow shields, photo survey), the following observations were made by RH staff:

- The orbit counter was operating smoothly and accurately and showing no sign of the suspect skips along it's path, throughout the entire range of orbit speeds and along all outer sectors of the Cyclotron.  In fact, according to Don Jackson, he could not remember the orbit counter ever working so well.

- The images from the outrigger cameras were noticeably more stable, showing less signs of structural vibration from the service bridge during orbit.

In my professional opinion, I believe this marked improvement in the orbit counter stability is due to the cleaning, lubrication and re-fitting of the center post bearing assembly described in the previous section above.  Don Jackson could not remember the center post bearing ever being serviced.  I have certainly not been able to find any written record of such service.  If that bearing was poorly lubricated and not rotating smoothly, then vibrations, seizing, and sticking would have result during rotation.  Any skip, jump, or vibration from such a sticky bearing would be amplified across the 30+ foot lever of the service bridge to the point at which the orbit counter wheel contacts the bridge sector.  These vibrations could likely have contributed to false orbit counter readings.  See photo below:

In any case, the orbit counter system has been observed to be operating normally and adequately by RH staff for several weeks of the 2012 shutdown.  I recommend that an automated tank survey is attempted as normal procedure, with both RH and RPG staff present to observe and document the behaviour of the orbit counter.

Thanks,

Grant Minor, Remote Handling