# US Commercial Light Water Reactors

**URL:** <https://boards.straightdope.com/t/us-commercial-light-water-reactors/771353>\
**Category:** Cecil's Columns/Staff Reports\
**Created:** [November 10, 2016, 1:36pm UTC](https://boards.straightdope.com/t/us-commercial-light-water-reactors/771353 "2016-11-10T13:36:03Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![ronindoman](https://avatars.discourse-cdn.com/v4/letter/r/d6d6ee/32.png) [@ronindoman](https://boards.straightdope.com/u/ronindoman)\
**Post date:** [November 10, 2016, 1:36pm UTC](https://boards.straightdope.com/t/us-commercial-light-water-reactors/771353/1 "2016-11-10T13:36:03Z")

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This is a good article about Heavy Water. It is used ,for instance in the Canadian CANDU reactors that are not enriched, i.e. the fuel is natural uranium.  
There’s one sentence that I believe needs to be changed , i.e. that " enriched reactors do not have a moderator" All US commercial reactors use enriched (up to 5 percent by weight in U-235). Fissioning occurs primarily with neutrons that have been “thermalized” or slowed down in speed by standard but pure, de-ionized water used as a moderator AND coolant. That’s why the term Light Water Reactors is used to described the US commercial reactors.

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**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\
**Post date:** [November 11, 2016, 2:07pm UTC](https://boards.straightdope.com/t/us-commercial-light-water-reactors/771353/2 "2016-11-11T14:07:20Z")

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Welcome …\*\*ronindoman \*\* … to the Straight Dope Message Boards !!!

When we post comments about specific articles, we like that the poster give a link to the actual article that they’re commenting on … so everyone can be on the same page.

I’ve tried to find it and haven’t had any luck … please give the title and link if you could … thanks in advance.

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**Author:** ![Arjuna34](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@Arjuna34](https://boards.straightdope.com/u/Arjuna34)\
**Post date:** [November 12, 2016, 3:52pm UTC](https://boards.straightdope.com/t/us-commercial-light-water-reactors/771353/3 "2016-11-12T15:52:02Z")

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This may be the article:

[Is “heavy water” dangerous?](http://www.straightdope.com/columns/read/2135/is-heavy-water-dangerous)

> [@](#):
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> Reactors using enriched uranium don’t require a moderator.