[ RadSafe ] Hydrogen Venting & Spent Fuel Pools

[Anagnostopoulos, Harry]

RADSAFERS;

Here's a few bits of information to add to the "shared pool of
knowledge". I worked at a BWR-4 with a Mark-1 containment many years
ago.

1. Hydrogen venting

To reduce pressure in the reactor vessel, steam was dumped to the
suppression pool (torus), which is 1/2 full of water. There are systems
in-place to cool the water in the suppression pool, but they require
electrical power. Eventually, the torus needed to be vented to reduce
the pressure in the primary containment. Apparently, in the 1990's, such
vents were added to older Japanese plants. These vents vented to the
reactor building and lead to the explosions in the reactor buildings.
I'm sure that the operators were aware of this possibility when they
made the tough choice to vent...

2. Spent Fuel Pool heating

SFPs need cooling and recirculation. The amount of cooling depends on
the decay heat from the fuel in the pools. Immediately after core
un-load, the heat load is significant. This changes with time. During a
refueling outage, the cooling is periodically stopped and monitored so
that the "time to boiling" can be calculated. Eventually, this time
becomes indefinite.


BTW, I deleted all previous history and header information when replying
to RADSAFE. It kinda makes the message shorter. Perhaps some of us could
give it a try?



Harry Anagnostopoulos, CHP
Navarro-Intera
Nevada

"In preparing for battle I have always found that plans are useless, but
planning is indispensable."
-    President Dwight D. Eisenhower