B&W PWR

[wlrun3@aol.com]

What is the difference between a raised loop, Davis-Besse, and a lowered loop, Arkansas Unit 1, B&W PWR?
These are the descriptions provided on the NRC website.

[thenuttyneutron]

Raised loop means the bottom of the SG is at about the same level as the reactor.  This makes the thermal center higher.  In the lowered loop design, the SG sits lower relative to the reactor than the raised loop design.  The thermal center is not as high in the lowered loop plant.

The benefit of a raised loop is with natural circulation in the event that you lose forced flow.

[wlrun3@aol.com]

Is the raised loop B&W PWR the more advanced of the two in the B&W product line?

[Fermi2]

Yes it is. In fact Bellefonte is a raised loop design.

[jams723]

Raised loop means the bottom of the SG is at about the same level as the reactor.  This makes the thermal center higher.  In the lowered loop design, the SG sits lower relative to the reactor than the raised loop design.  The thermal center is not as high in the lowered loop plant.

The benefit of a raised loop is with natural circulation in the event that you lose forced flow.

The lower loop design still develops natural circulation.  But the raised loop is more conducive to NC.

[Frankie Love]

Was all of this a natural progression in engineering or was it part of (made my career) TMI mods?

[Fermi2]

Natural Progression. DB was in service when TMI happened, in fact DB had a TMI type event before TMI did.

[SloGlo]

Natural Progression. DB was in service when TMI happened, in fact DB had a TMI type event before TMI did.

so did oconee.

[Frankie Love]

Natural Progression. DB was in service when TMI happened, in fact DB had a TMI type event before TMI did.

Interesting...since my career began the September following TMI, I thought I would have heard of the DB and Oconee incidents. I'll check Wiki but is there other methods of interesting research or reading?

Thanks. Learn something new everyday still holds true.

[Higgs]

Interesting...since my career began the September following TMI, I thought I would have heard of the DB and Oconee incidents. I'll check Wiki but is there other methods of interesting research or reading?

Thanks. Learn something new everyday still holds true.

Yeah had the industry communicated its lessons learned back then, TMI could have been prevented, or at least handled correctly based on what happened a few months earlier at DB.

Justin

[Fermi2]

B+W ECCS department had actually compiled a great synopsis on the DB event, including some recommendations that appeared in various forms in virtually all PWR EOPs, but it was sitting in B+W customer service as they wanted to ensure it didn't commit B+W to anything and so it would be worded as a  "Hey we're doing this as a service to our customer and not sitting hard and fast recommendations for which we may later be held accountable for" sort of thing.