GOT WATER?

The document explains how nuclear power plants use water to absorb waste heat and cool equipment, detailing once-through and closed-cycle cooling systems. It highlights the significant volumes of water required, the environmental impact on aquatic life, and the critical role of the Ultimate Heat Sink (UHS) during accidents. The author argues that the primary safety hazard is not radioactive leakage, but rather the failure of water to reach the plant or leaking into the plant.

• Nuclear power plants are approximately 33 percent efficient, meaning two-thirds of the thermal energy generated by the reactor core is released as waste heat into the environment.
• Once-through cooling systems require vast amounts of water; for a typical 1,000 Mwe reactor with a 30ºF temperature rise, approximately 476,500 gallons per minute are needed.
• Closed-cycle cooling systems, while using less water than once-through systems, still require significant makeup water to compensate for vapor loss and to maintain water chemistry. For example, the Susquehanna nuclear plant in Pennsylvania requires nearly 30 million gallons of makeup water per day in summer.
• Service water systems operate continuously, 24 hours a day, to cool equipment such as air conditioning chillers and spent fuel pool heat exchangers, even when the reactor is shut down.
• During an accident, plants rely on an Ultimate Heat Sink (UHS) to provide all cooling and makeup water needs for the first 30 days. Emergency service water (ESW) systems typically require 10,000 to 30,000 gallons per minute when a lake, river, or ocean serves as the UHS.
• The withdrawal of large volumes of water adversely affects aquatic life through impingement and entrainment. A 2005 study estimated that the San Onofre nuclear plant impinged nearly 3.5 million fish in 2003, which was about 32 times more than 10 other coastal plants combined.
• The document asserts that the most significant nuclear safety hazard is not the leakage of radioactive liquid into water sources, but rather the failure of water to reach the plant or the occurrence of water leaks into the plant.

APA

Union of Concerned Scientists (2007). GOT WATER? https://www.ucs.org/sites/default/files/2019-10/20071204-ucs-brief-got-water.pdf

Chicago

Union of Concerned Scientists. GOT WATER? 2007. https://www.ucs.org/sites/default/files/2019-10/20071204-ucs-brief-got-water.pdf.

Wikipedia

{{cite report |author=Union of Concerned Scientists |title=GOT WATER? |date=October 2007 |url=https://www.ucs.org/sites/default/files/2019-10/20071204-ucs-brief-got-water.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{unionofconcernedscientists2007got, author = {{Union of Concerned Scientists}}, title = {{GOT WATER?}}, institution = {Union of Concerned Scientists}, year = {2007}, month = oct, url = {https://www.ucs.org/sites/default/files/2019-10/20071204-ucs-brief-got-water.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }