Document: NUREG-0800
Document ID: b1bccb14-17b6-422b-93ee-6d4f00b6512b
Document Type: srp
Title: CHILLED WATER SYSTEM
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1510/ML15103A559.pdf
Revision Date: 2023-06
Chapter: 9
Section ID: 9.2.7
CFR Part: 
CFR Title: 

Content:
chemistry, chemical controls and or system filters/strainers may be required since the plate-type heat exchangers employ narrow clearances (generally in the 3 mm (0.118 inches) or less range). System leakage and radiological considerations are reviewed due to the large number of gaskets utilized in the design of the plate-type heat exchangers. The effects of chemical controls are reviewed by the secondary review organization. D. Design considerations and provisions are made to address CWS voiding and gas intrusion. Gas intrusion or air voids have an extreme negative effect and may cause the CWS pumps to become non-functional and not able to perform their intended function. E. For safety-related mechanical chillers, they are selected and arranged to provide reliability and redundancy to transfer heat. Review emphases are placed on: i. Air cooled mechanical chillers are adequately designed to the outside environmental (dry bulb) conditions. ii. Chiller (condenser, evaporator, and compressor) design margins. iii. Instrumentation and controls such as chiller panel alarms, temperature controls for the returning chilled water, and chiller protection trips (for example, freeze protection) with consideration to automatic starts of standby chillers during normal and abnormal conditions. 9.2.7-18 Revision 0 – September 2015 iv. Potential for oxygen displacement in mechanical equipment rooms due to catastrophic release of refrigerant. Certain refrigerants may require a refrigerant leak detection system. Evaluation against potential effects to MCR occupants is performed by secondary reviewers. iv. Over-cooling the condenser refrigerant. v. Determine if a refrigerant purge unit is required for removal of noncondensable gases. This may be a safety-related to nonsafety-related interface. F. CWS pumps are adequately designed related to net positive suction head required (NPSHr) and are evaluated against NPSH available (NPSHa) under normal and accident conditions. Potential CWS