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HVAC Training

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Title:

Chiller Maintenance

Lesson Plan

NMH30C000105

On 9/20/04, Operations personnel at Hope Creek identified a refrigerant leak after noticing the

formation of ice on a skid mounted CUNO filter. Immediate actions performed included securing

the chiller, evacuating the area for personal safety issues due to the presence of R-114

refrigerant, and pumping down the chiller refrigerant charge to the storage vessel.

Because of the leak, the 1BK403 chiller was declared inoperable. Station personnel

subsequently determined that improper installation and assembly of the CUNO filter caused the

leak.

Initially, maintenance personnel considered that the refrigerant leak was coming from the filter

o-ring gasket; however a follow-up maintenance inspection found the filter housing to be slightly

tilted from vertical, and missing the band clamp used to ensure that the filter is securely

fastened in its cradle. A review of work history indicated that the filter cartridges had recently

been replaced in August 2004 during a planned maintenance activity.

To repair the leak, maintenance personnel removed the filter sump, re-welded the filter cradle

to the chiller skid, and installed a new filter head o-ring gasket and sump. Post-maintenance

pressure testing of the chiller verified that the leak was repaired, and 1,150 lbs of R-114

refrigerant was added to the chiller prior to releasing it to station operators for operability

testing. Satisfactory testing of the chiller was completed and the LCO exited at approximately

0447

hours on 9/25/04.

During the repair process, station personnel performed walk-downs on all Hope Creek

centrifugal chillers and confirmed that their installed piping and filter configuration were

satisfactory. A review of maintenance procedures was also performed at that time, and the filter

manufacturer was also consulted.

As a result of these reviews, it was determined: 1) That the leak occurred due to improper

installation of the CUNO filter, 2) That the existing maintenance procedure contained

insufficient guidance for proper removal/installation of the filter sump and for the replacement of

CUNO filter elements, and 3) That the missing band clamp probably did not contribute to the

formation of the leak, although it does provide additional support to the filter and copper

refrigerant line.

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Carrier 19FA Istruzioni per gli Interventi Pagina 38