[ RadSafe ] BWR SCRAM sequence

[Olsson Mattias :MSO]

Not that this has much to do with my tasks, but in general at an ASEA Atom BWR (similar to GE) the regular SCRAM includes:

- Hydrualic insertion och control rods (ca 4 s)
- Down regulation of main circulation pumps
- Different feedwater regulation
- Start of cooling of the wet well condensation pool

If the scram is combined with no possibility of dumping steam to the condenser, steam is blown into the condensation pool.

/Mattias Olsson, Forsmark NPP, Sweden


-----Ursprungligt meddelande-----
Från: radsafe-bounces at health.phys.iit.edu [mailto:radsafe-bounces at health.phys.iit.edu] För Doug Aitken
Skickat: den 17 mars 2011 15:17
Till: 'The International Radiation Protection (Health Physics) Mailing List'
Ämne: Re: [ RadSafe ] BWR SCRAM sequence


As a person with only a basic understanding of the workings of these reactors, any detail will be very welcome. One question I keep getting is what happens if the rods melt and pool in the base of the containment. Will the mass of material go critical? 

Regards
Doug

Doug Aitken
QHSE Advisor, Schlumberger D&M Operations Support
Cell Phone: 713-562-8585
(alternate e-mail: doug.aitken at slb.com )
Mail: c/o Therese Wigzell,
Schlumberger,
Drilling & Measurements HQ,
300 Schlumberger Drive, MD15,
Sugar Land, Texas 77478



-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of James Barnes
Sent: Thursday, March 17, 2011 8:30 AM
To: radsafe at health.phys.iit.edu
Subject: [ RadSafe ] BWR SCRAM sequence

Dear all;

Being primarily a PWR HP, I was hoping some of you BWR types might help me with something.

During a normal SCRAM on a BWR, am I correct in assuming that the steam generated by the reactor is shunted directly to the turbine condenser so it can be used as a heat sink?

Can somebody walk me thorugh the sequence of SCRAM to cold shutdown as to how the various systems are activated and approximately what conditions trigger those systems?

This is during a "routine" SCRAM (sudden rod insertion) resulting in the system being taken to cold shutdown.  Not a LOCA or some other type of outlier event.

Thanks,

James Barnes
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