[ RadSafe ] PARs for LWRs [was "Risk Communication"]
jaro_10kbq at videotron.ca
Thu May 16 17:55:17 CDT 2013
TEPCO will be installing PARs in Kashiwazaki-kariwa NPP....
...can the rest of the Japanese NPP fleet be far behind ?
From: Jaro Franta [mailto:jaro_10kbq at videotron.ca]
Sent: May-11-13 7:43 AM
To: 'The International Radiation Protection (Health Physics) Mailing List'
Subject: RE: [ RadSafe ] Risk Communication
The Canadian PARs units are installed in Candu stations and some LWR
PAR units are installed in nuclear plants in:
I don't know what size the IP-2 PARS units are, but a typical Candu station
requires close to thirty PARs, which are boxes roughly two feet square each
(like an oversize ashtray).
As new self-start threshold 2% H2 with available oxygen Operating range 1%
to ~8% hydrogen Capacity increases about linearly with hydrogen
concentration Capacity increases with pressure
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Steve Schulin
Sent: May-11-13 4:08 AM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: Re: [ RadSafe ] Risk Communication
Hi Jaro - Well, I see that USNRC's draft "Director's Decision", issued last
month, denies the NRDC petition, but not because NRC disagrees that the PARS
at Indian Point-2 (with its two installed PARS units) would be an ignition
hazard in some severe accidents. NRC staff has concluded that the benefits
of PARS in coping with design basis accidents -- station blackout in
particular -- outweighs the risks added in the case of beyond design basis
accidents, because severe accidents are so unlikely.
Your message seemed to point to beyond design basis accident at Fukushima as
rationale for PARS. I appreciate your comments and your knowledge of how
Chalk River analyzed PARS. Was it the isotope production reactor there that
you were working on? If you didn't have to install thirty-to-sixty IP-2
sized PARS units (each one is capable of handling several grams of hydrogen
per second), then you were dealing with less maximum hydrogen than the big
US LWRs. NRDC says the two PARS units at IP-2 are sufficient for
design-basis accidents. And NRC does not contest that they would be
overwhelmed in more severe accidents, in which hydrogen production is
projected to be as much as 10 kilograms/sec.
The draft DD is available via NRC's ADAMS document ACN ML130501596
Very truly yours,
Steve Schulin, Founding Editor
info at nuclear.com
On May 10, 2013, at 7:28 PM, Jaro Franta wrote:
> Hi Steve,
> You don't seriously believe *any* of the BS spread by the Natural
> Resources Defense Council ?
> Having been involved in preparing licensing-related documentation for
> PARs installation in Canada, I would like to share some basic
> information that I reviewed & used in my documents, referenced from
> numerous development & test reports written by the folks who developed
> the Canadian version of PARs, in Chalk River Nuclear Laboratories.
> First of all, PARs can NOT increase the likelihood of a hydrogen
> explosion in a beyond design basis accident, because they self-start
> at a hydrogen concentration that is well below that required for an
> Once PARs self-start, they have a high capacity for hydrogen
> recombination, which heats them up to roughly the same temperature as a
> A plant-specific analysis is prepared by the licensee for the
> regulator, to indicate how many PARs need to be installed, and in
> which specific locations, to ensure that adequate recombination
> capacity is available under all circumstances.
> Secondly, US NPPs already have electric-powered hydrogen "igniters".
> The problem with those is not that they will blow up the pant, but
> that they don't work in a total station blackout situation, like
> Regarding the issue of containment vent filter clogging, sure, a
> poorly designed filter can clog.
> A similar issue arose in past years regarding containment cooling
> recirculation: New pump intake filters had to be designed, built and
> installed at nuclear plants, to ensure that even under the worst
> conceivable circumstances adequate water could be circulated from the
> containment sump, to maintain cooling.
> Ignoring appropriate solutions is simply another way of saying
> dragging your feet.....
> -----Original Message-----
> From: radsafe-bounces at health.phys.iit.edu
> [mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Steve
> Sent: May-10-13 6:43 PM
> To: The International Radiation Protection (Health Physics) Mailing
> Subject: Re: [ RadSafe ] Risk Communication
> Hi Jaro, and all. One reason I don't support use of PARS is because
> such devices can actually increase the likelihood of a hydrogen
> explosion in a beyond design basis accident. See "passive
> autocatalytic recombiners could act as hydrogen igniters in beyond
> design basis accident" at
> I'm also not so keen to put filters on the hardened vents. The safety
> function of the vents is so important that it seems unwise to risk
> clogging up the vent path. I'm no engineer, but as a radiation
> protection technician, and as a homeowner, it it has been my
> experience that filters clog.This concern about filter-clogging was
> raised in at least one of the post-Fukushima ACRS meetings (NRC's
> Advisory Committee on Reactor
> Safeguards) where the filtered vent issue was discussed, but I haven't
> noticed any studies or reports on the subject.
> As to contributors to public outrage, I'd rank several items as of
> much greater significance than the explosions. The admission by TEPCO
> that they purposefully did not improve tsunami protection to guard
> against increased max credible tsunami height is one example. That the
> reasoning included not wanting to alarm the public was an especially
> egregious aspect of this, and I see this raised in many more recent
newspaper pieces than the explosions.
> Very truly yours,
> Steve Schulin, Founding Editor
> info at nuclear.com
> On May 10, 2013, at 5:36 PM, Jaro Franta wrote:
>> Thanks for the link.
>> It seems to me that a very big part of the "Outrage" following
>> Fukushima came from the public seeing images of one reactor after
> blowing up.
>> Does anyone dispute that assertion ?
>> Anyway, a fairly easy and relatively inexpensive way to combat that
>> specific outrage is to make sure that NPPs subject to total station
>> blackout do not blow up, because of hydrogen accumulation.
>> Now why on earth is the US nuclear industry dragging its feet on
>> installation of Passive Autocatalytic hydrogen Recombiners (PARs),
>> while everyone else around the world is installing them, is totally
>> Similarly for containment venting filters.
>> How about some leadership for a change ?
>> Jaro Franta
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