Randall
Pickering 5 returned to power on July 5 2007 following a maintenance outage started Ap 2 2007. All 12 reactors at Pickering B + Bruce B + Darlington are operating, plus Bruce 4. Bruce 3 was shut late July 9 for a repair to a valve motor. Bruce Power predicts a short outage.
As for the Pickering A outage, it may be (I'm speculating here) that the "back up" electrical power system is more important for Pickering A than for Pickering B, because Pickering B has 4 reactors operating and PB has only 2. IF this is the case then it is less likely for PB to require supply from its back up system than for PA, because of the difference in numbers of operating reactors. This is merely speculation on my part.
I do not think the lack of specific details on the outage is an example of OPG being secretive, just that most people and the media probably do not care why the reactors are shut, but only that they are shut. The amount of detail supplied is OPG's choice. I work for the nuclear industry and have no more information than that released by OPG. You could always ask OPG for more detail.
If the Canadian Nuclear Safety Commission (CNSC) decrees a system must be operable (i.e., as part of the operating licence), then the operator must ensure the system is operable or cease to operate the reactor. The operators have no choice but to repair or modify a system if a problem is identified that puts continued operation outside the licenced operational envelope. Note that operation outside the operational envelope is not necessarily unsafe, because the envelope itself is well within the safe operational limits of a reactor. An analogy (all analogies have faults) is that a particular car (and driver) might be able to operate safely on a given highway at 150 km/hour, but that the regulator (Ministry of Transport) has decreed that 100 km/h is the limit. The CNSC regulates the power plant operators much more closely (and operators are mandated to report certain events, system unavailabilities, etc.) than is the case for vehicle operation (there are only so many police officers).
Also, the nuclear operators run their stations well within their allowed (licenced) limits. If the margin between continued operation and the licenced operational envelope decreases to less than what an operator will tolerate, then they will shut the reactor(s) address the problem, even if they are still able to operate within the licence envelope. To continue the highway analogy, a vehicle operator may chose to operate at 90 km/h because their own internal margin is to maintain the vehicle 10 km/h within the regulatory limit.
I'm sure OPG is also using the outage time to perform other maintenance that would otherwise have been delayed to the next maintenance outage.
cheers
Morgan Brown
-----Original Message-----
From: cdn-nucl-l-admin@mailman1.cis.McMaster.CA
[mailto:cdn-nucl-l-admin@mailman1.cis.McMaster.CA]On Behalf Of Randal
Leavitt
Sent: July 10, 2007 4:03 PM
To: Nuclear
Subject: Re: [cdn-nucl-l] Pickering Not There
Paul Wilson wrote:
> Hello all,
>
> It is probably worth clarifying the term "backup system" that is being
> used in these stories too....
This would help, but what would help even more would be a lot more
information about what is going on at Pickering. I read the newspaper
story, where is said that a backup system was not working. If X is a
system, then the "backup for X" is another system that jumps in when X
fails. It seems that the word "backup" was being used to mean something
else. I admit that I am confused by all this. Is there any way to get
more details? The way I see it, the safety of having enough energy to
prevent heat deaths in our cities is being compromised by the safety of
having two reactors shut down. One person's safety is another person's
problem. Yes, I know that electricity can be bought to cover this
situation, but that does not reflect well on the desirability of nuclear
power in general.
No doubt the approach taken is a sensible one, but the explanations
given do not seem to be adequate. It seems to be difficult to get a
good explanation. All this creates the impression of a troubled and
secretive industry, exactly what is not needed.
The OPG press release states that the A side gets its power from the B
side, or from this "backup system" if the B side connection fails. Does
the B side get its power from the A side? That would be difficult now
that the entire A side is shut down. Is the B side being run on diesel
power while the A side is down?
While trying to find out about this I seem to have discovered that
Pickering B Unit 5 is also down. It seems that Pickering is running at
half power at this point. Is that right? To me that seems like
discouraging news.
--
Randal Leavitt - another Ubuntu user
http://positiveenergy.blogspot.com/
http://www.simpy.com/user/randalleavitt/links
http://tinyurl.com/hgvmg
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