Re: [Phys-l] Japan situation : information, or lack thereof

[Hugh Haskell <haskellh@verizon.net>]

At 3:49 PM -0500 5/3/11, William Maddox wrote:
> Perhaps civilian power plant owners and operators could get help from
> the US Navy. The USS Enterprise has 8 reactors but has been down to 1
> operating reactor while at sea. There are problems getting a ship that
> size in and out of port in Hawaii without the pipes that supply water to
> cool the steam getting clogged. So it is possible to have a "self
> contained" pressurized water reactor. Is there a technical reason this
> can't be done with a boiling water reactor (as opposed to greed or poor
> design)?
>
> Apparently the US is going to be spared its own reactor/cooling pond
> meltdown at Browns Ferry following shutdown after tornadoes went through
> Alabama last week. Two sources of offsite power have been restored. The
> reactors may be shutdown for 2-3 more weeks while the power lines are
> repaired so the reactors can supply power to Alabama.
It is true that Enterprise has 8 reactors, but I have not heard that 
it ever got down to one operating reactor. I served on board 
Enterprise (albeit not in the reactor department) from 1967-69, at 
the tail end of a fuel cycle (I left the ship as is pulled into 
Norfolk for its second refueling). The reactor officer was a friend 
of mine and so I knew something about how the reactors were 
operating, since the fuel was nearing the end of its useful life he 
had to nurse the reactors with some care. If they were put under much 
stress the xenon fraction in the fuel rods would zoom up and the 
reactors could scram due to the high neutron capture x-section of 
xenon, so our maneuvering was somewhat limited, and all major power 
changes had to be scheduled in advance so as to avoid the xenon 
effect. But I do not believe that any of the reactors ever shut down 
other than intentionally while I was on board. This may have happened 
either before or after my time, but not while I was there.

Later nuclear carriers have only 2 reactors (which together put out 
more power than did the 8 on Enterprise while I was there). That 
would require very careful management to make sure that neither of 
the reactors are unintentionally scrammed while at sea, especially 
while in battle. No US warship has come under hostile fire while 
operating at sea since WWII, so we still don't really know how the 
nuclear carriers will perform in combat, and given the nature of the 
world today, we may never be in a position to find out. I don't look 
forward to one of those ships being sunk and spilling its nuclear 
fuel all over the bottom of the ocean.

I think the Enterprise reactors were BWR, but I'm not sure. My only 
clue is that the steam the reactors generated was only about 550 
degrees--the ship had no superheaters and used saturated steam 
instead--an outdated propulsion technology. Oil-fired combat ships 
have for years had superheaters that generate operate on 1300-degree 
steam, at much greater efficiency and responsiveness than using 
saturated steam would allow. I often wondered about this but didn't 
know enough about reactor technology at the time to ask the proper 
questions. Newer reactors may have superheating capability, but I'm 
not sure. I doubt that superheating is all that useful for a 
land-based power plant since they usually operate either at full 
power or off, but a ship's reactor has to be capable of providing 
rapid response to changing bell signals from the bridge, and 
superheating may be a worthwhile capability for them to have, but, as 
I said, I don't know if that capability is available to them, even 
today. In any event it seems logical that a PWR would be more capable 
of supporting a superheating system than a BWR, hence my assumption.

As to getting in and out of Pearl Harbor. I was aboard Enterprise 
when her condenser intakes got clogged with mud as she was getting 
underway. It was a bit embarrassing, but caused only an ignominious 
tow the 200 yards from the "sticking point" back to the pier, and a 
several-hour delay in sailing. We cleaned the pipes, waited for high 
tide and we were on our way. I suspect that following that incident 
the harbor was dredged to a few feet deeper. After all, those hogs 
displace around 100,000 tons and draw upwards of 36 feet when loaded. 
Not as much as a supertanker, but those guys never even come into 
port. They off-load at pumping stations often several miles out to 
sea.

I'd be interested in hearing details on when "the Big E" was reduced 
to a single reactor.

Hugh
--

Hugh Haskell
mailto:hugh@ieer.org
mailto:haskellh@verizon.net

It isn't easy being green.

		--Kermit Lagrenouille