1. Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada Canada’s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules Accelerating Science for Canada Un accélérateur de la démarche scientifique canadienne Cooling Water What could be easier than providing cool, clean water in Vancouver? Doug Preddy | Beamlines Group Leader | TRIUMF ARW 2013 – Melbourne, April 14 – 19, 2013

2. Overview of cooling water systems Cooling water is the lifeblood of many systems in an accelerator facility. Without adequate cooling water most powered equipment would not be able to operate. Many factors are involved with providing a good supply of cooling water to equipment. Monitoring the water’s quality is as important as the initial design of a water system. Care must be taken to ensure the quality of cooling water is maintained.

3. Water system schematic

4. Deionised water Up to 5000 litres are stored in a tank as closed loop make up water. We use deionised water in all our closed loop water systems. Deionised water is made on site although we can buy large quantities if required.

5. What do we keep track of? Pressure Supply ~100psi Return ~20psi Temperature Supply 24 deg. C Return up to 50 deg. C Resistivity Typically 5 to 15 Megaohms/centimeter Dissolved oxygen content Typically DON’T KNOW!!!!!!!!! For equipment we also monitor differential pressure and water flow rates.

6. How is water quality maintained? Resistivity is maintained by running a side stream of water through a resin can. Dissolved oxygen is not presently controlled, but we are now investigating ways to control the dissolved oxygen content in our closed loop water. Filters are used to ensure particulates are removed. Depending on the system the filters remove particulates from 25 microns down to 1 micron. The raw water systems are conditioned with various chemicals to inhibit algae and corrosion. Phosphates

7. How is water quality maintained? When equipment is not being used we try to maintain water flow through the equipment. If this is not practical we blow all the water out of the equipment when it is stored. When equipment is put into service it is flushed with clean water from our system before it is hooked to the closed loop water.

8. Problems we have encountered Resistivity decreasing Resin cans used up Adding non-conditioned water Beam related introduction of ions Cooling circuits blocked Particulates introduced into system Fouling of circuits due to chemical reactions Fouling of circuits due to corrosion Leaks Corrosion related leaks Hoses and fittings failing

9. Resistivity Maintenance of the resin beds is crucial Monitoring of resistivity levels and reacting to changes Oil or grease from new piping can foul the resin bed Addition of non-conditioned water Any water introduced into the system must be deionised water. New equipment connected to the system must be flushed with system water Beam related introduction of ions High radiation levels can interact with the cooling water in the target areas resulting in lowered resistivity

10. Blockages to cooling circuits Filters Spun cotton filters between 1 and 25 microns Bypass valves installed so equipment does not have to be turned off when servicing filters Chemical reactions Phosphates in the water caused copper phosphate to foul circuits Corrosion Dissolved oxygen in the water will react with copper to form copper oxides. When the oxygen content changes these oxides can be released into the system.

11. Leaks Corrosion Deionised water is quite corrosive. Brass fittings will become porous as the zinc is removed from the fitting Galvanic corrosion is caused by dissimilar metals Ageing equipment Rubber hoses have a finite lifetime especially in radiation areas Cavitation can quickly erode metal parts High velocity water can wear parts Vibration or repeated motion can cause stress induced cracks to form

12. Quadrapole magnet problem

13. BL1AQ15 blockages These parameters combine to break down the water in the cooling circuits, releasing positive ions into the water These positive ions combine with the copper in the cooling circuits producing copper oxides The copper oxides quickly plug the cooling circuits of the magnet

14. 1AQ15 Blockages As the magnet’s temperature rose too high to safely operate, the magnet was flushed with a high temperature (100C) alkaline chemical flush. This flushing procedure was required every four months. By connecting the positive side of the magnet to ground, rather than the negative side, the ions were repelled from the copper coils. This has reduced the corrosion rate significantly. The magnet now requires flushing only once per year.

15. Leaking heat exchanger Triumf uses a number of chemicals to protect the raw water system from corrosion and algae growth. One of the main chemicals is a phosphate based algae inhibitor. We had a raw water to non-active heat exchanger leak from the raw water side to the non-active side. This introduced phosphates into the closed loop system. The phosphates reacted with the copper cooling lines producing copper phosphate. This fouled the small cooling lines in many steering magnets and diagnostic equipment.

16. Pressure back flushing To remove the copper phosphates we tried to simply back flush the equipment with water This was not very effective so we went to a procedure that used compressed air to force water to flow through the equipment in a very turbulent manner. This was very effective in removing the copper phosphate, but resulted in other problems very quickly.

17. Dissolved oxygen content problem Flushing the cooling lines with pressurized air introduced higher than normal concentrations of dissolved oxygen in the cooling water. The rate of corrosion increases greatly as the dissolved oxygen content reaches ~200parts/billion The resulting precipitate once again caused numerous blockages in cooling lines. We are now in the process of chemically flushing these cooling lines. Procedures to limit the introduction of oxygen into the closed loop system are now being looked at.

18. Main Magnet power supply leak The main TRIUMF cyclotron magnet power supply developed a leak in one of the transformers inside the power supply. This was traced back to a cooling circuit that was not well designed. High velocity water flowing through too tight a bend in the transformer cooling circuit wore a hole in the tubing. The magnet would have been shut off for a long period of time waiting for a replacement transformer, so the inside of the cooling line was coated with epoxy as a temporary fix.

19. Conclusion Maintaining a cooling water system requires constant vigilance Most problems can be avoided with a good maintenance program and avoiding contamination being brought into the system Proper design of equipment and water systems is very important for a low maintenance, long life facility

20. Owned and operated as a joint venture by a consortium of Canadian universities via a contribution through the National Research Council Canada Propriété d’un consortium d’universités canadiennes, géré en co-entreprise à partir d’une contribution administrée par le Conseil national de recherches Canada Canada’s national laboratory for particle and nuclear physics Laboratoire national canadien pour la recherche en physique nucléaire et en physique des particules Thank you! Merci TRIUMF: Alberta | British Columbia | Calgary Carleton | Guelph | Manitoba | McMaster Montréal | Northern British Columbia | Queen’s Regina | Saint Mary’s | Simon Fraser | Toronto Victoria | Winnipeg | York