Saturday, March 9, 2013

Post # 79: To Vent, Or Not To Vent: That Is The Question!

On the eve of the two-year anniversary of the accident at Fukushima Daiichi, the U.S. Nuclear Regulatory Commission (NRC), and the U.S. nuclear power industry are making progress dispatching the twelve recommendations of the NRC's Near-Term Task Force (NTTF) Review of Insights From the Fukushima Dai-ichi Accident.

The NRC is currently working to resolve a major question about the continued safe operation of the nation's commercial boiling water reactor (BWR) fleet.  The question at hand, driven by NTTF Recommendation 5.1, is "Should hardened, filtered, primary containment venting (FCV) systems be required as backfits to the nation's thirty one commercial boiling water reactors (BWRs) that are similar to the units at Fukushima Daiichi?"  Or, as Shakespeare's Hamlet might put it, "To vent, or not to vent, that is the question..."

(Public Domain image from

Regardless of one's view on the matter, one has to have some sympathy for our colleagues at the NRC.

The NRC staff issued its analysis of the question in SECY-12-0157 (November 2012).  Their conclusion was that engineered filtration systems should be required.

On January 15, 2013, the U.S. House of Representatives Committee on Energy and Commerce  (dominated by Republicans) wrote a 10-page letter to the NRC saying, in essence, "Slow down.  You're moving too fast!"  The letter questioned whether the hardened filtered vents are needed, and reminded the NRC that it took some actions in the wake of the accident at TMI that were later judged to be unnecessary or otherwise ill advised.

Not to be outdone by their House colleagues, on February 20, 2013, the Senate Committee on Environment and Public Works (dominated by Democrats) sent the NRC a letter, saying, in so many words, "You should require the vents.  Get on with it, now!"

In the mean time, the Industry's position on the hardened vents can be summarized as, "Wait a minute!  Not so fast!  We're implementing the FLEX strategy.  We need to understand all the implications of the FLEX strategy before we require the plants to spend buckets of money installing hardened filtered vents.  And oh, by the way, unless one can prevent the containments from failing (thus at least partially bypassing an engineered vent system), money spent on a hardened, filtered vent is money wasted.  Far better to put the money into systems that can prevent the containment from failing."

It is important to remember that none of these questions, and non of these positions are new (see NRC Generic Letter 89-16).  It's "deja vu all over again" as Yogi Berra said.  These same questions and issues arose back in the early-mid 1980s when we were taking the first serious look at BWR severe accidents.  I recall two basic viewpoints about filtered containment vents that arose then and are implicit in the dialog today:  On the one hand, "Vents are a nod to what you don't know you don't know – a last best safety net (or barrier in the multi-barrier containment concept), and thus filtered vents should be required."  The counter argument was, "Yes, we don't know what we don't know, and the unintended consequences of installing a filtered venting system may overwhelm the benefits – so FCVs should NOT be required."

It's fascinating to realize this dilemma has not been resolved despite thirty years of risk-informed regulatory debate.

I recently sat-in via telecon on an NRC / Industry public meeting on the matter of whether hardened filtered vents are to be required and how the NRC plans to make that decision.  Buried in the dialog is a fascinating techno-philosophical issue that juxtaposes the desire for passivity in our safety systems, and the need for reliability and safety system effectiveness.  The attraction of a passive system is that it requires no human action and no outside power sources to act.  Most passive containment venting concepts I'm aware of employ a vent flow path that "once open, is always open."  This also means once the vent is open (functioning), the filter system becomes vulnerable to any dynamics loads or forces that might be placed on it from explosions or energetic events in the containment.  The effectiveness of a passive filtration system after such an event is obviously in question.  In a perfect world, one would prefer the ability to remotely or manually open and close ("modulate") a hardened vent line as the accident progresses, thus protecting the vent filtration system from damage and ensuring its effectiveness when it is needed.

But, as anyone who has analyzed the response of BWR reactor buildings during severe accidents knows (and the accident at Fukushima illustrates), the ability of personnel to maneuver through a reactor building to reach equipment requiring manual operation can be severely limited by the environmental conditions created by the accident.  And the idea of a completely passive filtered containment venting system that can open and close as needed is a bit like the idea of a "one-ended stick"... hard to conceptualize.

Completely aside from the technical issues involved, the NRC faces the very practical, but still highly philosophical issue of HOW to make the filtered vent decision.  There may be a good Ph.D. thesis in decision theory buried in there somewhere!

As I said, regardless of one's position on the matter of filtered containment vents, one has to have some sympathy for our NRC colleagues who are faced with untying this "Gordian knot".  Hamlet could relate to their dilemma.

Just thinking...

Friday, March 1, 2013

Post # 78: The Aristocracy Of The Welfare Class

Relative to my last post regarding federally-funded research and development, and with one eye on the upcoming federal budget sequester, I want to relate a funny and thought-provoking story about a conversation I had with a colleague at Oak Ridge National Laboratory some thirty years ago...

One day in the early 1980's,  I and a number of other "early-career" guys (yes, all guys) were sitting around the lunch table bemoaning the lack of support for our favorite R&D programs.  We swapped stories about the challenges of working within the federal R&D enterprise and the struggles we shared in dealing with volatile funding profiles and Washington politics.  Sitting with us (and listening quietly) that day was an older colleague.  I will call him "Henry" for the purposes of this story.  Henry was about the age I am now (late 50's), and had joined ORNL after a long career in the nuclear power industry.  Henry listened for some time to our groaning.  Then, with a twinkle in his eye, and a stroke of his graying red beard, he said in a voice salted with wisdom we were yet to acquire, "Never forget, Gentlemen, WE (speaking of those employed in the federal R&D establishment) are the aristocracy of the welfare class!"

Henry continued to explain that, while we complained about our taxes, our salaries were paid and our labs were equipped by everyone's taxes.  While we complained about federal handouts to various groups, we were at the "top of the federal food chain" when it came to taxpayer support.  Though we bemoaned the inefficiencies of the federal R&D establishment, our laboratory was a major element of that establishment.  And, while we groaned about constant bickering between and within the Legislative and Executive Branches over R&D priorities, we all had elected officials to thank for the continuance of our favored research programs.

Henry did not know it then, and I don't recall telling him later, but his comments that day had a profound impact on my thinking and my career.  For you see, it was at that instant I first recognized what a privilege it is to work in the federal R&D enterprise.

And it was in that instant I began to understand the responsibility those in the federal sector bear to "give back" to the tax payer some tangible positive IMPACT in exchange for the privilege of having their research supported by the taxpayer... the "Societal Contract" I mentioned in my previous post.

It occurs to me as I write this that today I am almost a perfect complement to Henry of thirty years ago.  I'm in my late fifties as he was then.  I've spent most of my career in the federal research enterprise and have now moved into private enterprise.  The vector of mine and Henry's careers have been almost exact opposites in that respect.  Yet the wisdom of Henry words from so long ago still ring in my ears.  Amen Henry! Preach on!

Just thinking...