Re: lochbaum on nuke plant aging

[Norman Cohen <ncohen12@HOME.COM>]

Hi Julian,



I forward this email and your previous one to Dave L for his comments. Whether

he comments or not is totally up to him, as he is not on radsafe and may have

other work to do.



Your previous email had much data in it that I could not refute or 'fute'

without research.



I'll make a few comments below.



julian ginniver wrote:



> Health Warning, the following is a lengthy response to the original posting

> that contains little information of relevance to radiological protection.

> Feel free to hit the delete button now if you wish although I will endeavour

> to make at least one reference to Radiation Protection in the posting (if

> for no other reason than to remind myself what I do for a day job)



---- At least you have a day job  ;-) ---



>

> Norm,

>         Is this posting your definitive response, as indicated in your

> e-mail 13 December 03:53, to my e-mail of 11 December (re recent safety

> hazards at ageing nuclear plants) or is there more to follow?



--- more to follow, after these words from our sponsor, the UNPLUG Salem

Campaign! ;-) ---



>

> In you reply I would be grateful if "you" could provide a definitive

> statement on whether US Nuclear Plants are having increased shutdowns due to

> ageing items of plant and equipment, as there seems to be some confusion in

> your postings on this issue.  The original posting implied that over the

> last three years "worn-out equipment at U.S. nuclear power plants has caused

> more than 50 fires, radiation or steam leaks or other serious safety hazards

> requiring shutdown of the nuclear reactor".



--- My understanding would be 'yes' more shutdowns. Your data seemed to indicate

'no'. Perhaps what was meant was more shutdowns and problems due specifically to

aging as against more shutdowns/problems all together.------



>  In addition Lochbaum states

> that "failures [of plant and equipment] are simply not being prevented

> because many nuclear plants have been forced to shut down since January 1,

> 2000, after ageing equipment broke".



--- Well, my reading of that is that since plants are already shut down, they

can't be shutdown again for other aging problems. Its not a clear sentence. Have

to give Dave a C- for English Composition.---



>

> Seems straightforward so far, Nuclear plants are getting older,  equipment

> is failing, the reactors have to be shutdown.  The incidents cited have

> happened since 1999 therefor the ageing nuclear stations are becoming less

> reliable and so less safe.  BUT then to muddy the waters Lochbaum also

> says "Every nuclear plant in the United States is in Region B! heading

> towards Region C!"  Lochbaum states that region B (of the bathtub curve)

> "reflects peak reliability during middle life".



--- It is my understanding that many of these nukes are already in region C of

the bath tub curve. So lets see what Dave says on that. It could be that he

means they are at the ass end of region B, and heading into Region C.----



>  Also if they [the nuclear

> plants] are heading towards region C, defined as "the wear-out phase" which

> has "high failure rates", then they have cannot have entered it.



> Can you see the dichotomy.



---yes -----



> Are the plants full of ageing components that are

> failing more frequently leading to more shutdowns? Or are the plants

> operating at peak reliability?



--- wouldn't say "peak". Would say working their way down the slope. ---



> In answering this you might wish to review my first reply, in particular the

> information on SCRAMS (unplanned shutdowns) per 7000 hours critical which

> appears to support the argument

> that the plants are operating at peak reliability during middle life.



--- indeed, thus one reason why I forwarded your reply to Dave. ----



>

> Could you ask Dave (Lochbaum - I hate referring to people just by their

> surname)



--- Thats OK, At the last NRC hearing UNPLUG and NRC had, NRC called him "Dave"

and me, "Mr. Cohen" At least with NRC I get respect. Radsafe you should be

ashamed!  ;-) ---



> to clarify his statement that "Cutting back on safety checks saves

> plant owners money, but it may someday cost lives."  This is because he

> earlier stated in his example that "Going from quarterly to annual tests

> reduces the number of failures [if equipment failed on every occasion that

> it was tested] per year from four to one.  On paper, safety is greatly

> improved.  But in the plant, safety is unchanged."  IF "safety is unchanged"

> by reducing the test frequency then HOW can "cutting back on safety checks"

> result in a potential loss of life?



----- Well I guess he is saying that eventually cutting back on safety and

relying on defense in depth

will result in a major problem.---



>

>

> Before looking in detail at the examples that Dave has given I would be

> grateful if you could ask Dave if he would consider using the date of the

> fault or incident in future rather than (as he did in the last posting) the

> date that the fault

> orincident was reported by the NRC or the operator.  This will help others to

> find information on these

> incidents more readily, and reduce the possibility that people reading several

> sources of information might mistakenly believe that there were multiple,

> separate incidents.



--- OK ----



> E.g Dave's item 6 (Diablo Canyon electrical fault) is listed as September 27,

> 2000.  In the original posting (by Chris Knap) it is listed as May 2000 (I

> believe it actually occurred on 15 May 2000).  Given the

> difference in dates it would be easy to assume that these were two different

> incidents, rather than the single incident it actually was.  I'm sure you

> would agree that it is important that people can accurately assess the true

> frequency of these types of occurrences.



--- yes ----



>

>

> In examining both reports that you have forwarded I was surprised at how few

> of the incidents were common to both.  Only item numbers (on Dave's list) 3

> (Indian Point-Tube Rupture), 6 (Diablo Canyon Unit 1-Electrical Fault), 7

> (North Anna Unit 2-Valve Failure) and 8 (San Onfre Unit 3-Electrical Fire)

> appeared on both lists. Why is this?



--- One guys just a lousy (according to radsafe) reporter, the other guys a

lousy (according to radsafe) engineer.

Real answer- I don't know.----



> It is clear from Dave's comments that he focused on events where he felt (as

> he highlighted) that ageing was a factor in the incidents. If this is the case

> then Dave considers that only a third of the incidents identified in the

> report by Chris Knap were caused by ageing.  Would you agree that this would

> appear to cast doubt on the validity of the Orange County Register report

> which cited the twelve incidents as the most significant of more than 50

> incidents caused by worn-out equipment?



--- Well, I'll agree it muddles up the water some, yes ---



>

>

> I would now like to review some of the incidents cited in Dave's report.

>

> Snip  2. March 14, 2000: The owner reported that Catawba Unit 1 in South

> Carolina had automatically shut down due to an inadvertent electrical ground

> problem. The owner reported "A detailed failure analysis determined that the

> root cause of the connector failure was the misapplication of the connector

> insert insulating material which is made of neoprene. ... The neoprene insert

> at the failure point on the connector exhibits signs of accelerated

> ageing [emphasis added]. The inserts are hardened and there are charred

> deposits on the end of the inserts which are indications of electrical

> tracking."<snip

>

> I think that Dave has missed the important lesson to be learned from this

> incident.  It is not the accelerated ageing of the neoprene insert that is

>  significant, it is the "misapplication of the connector insert insulating

>  material which is made of neoprene".  The root cause of this occurrence

> was not ageing, but the use of the wrong material.

>



---- but there was ageing... I'll let Dave answer further ---



>

> snip > 3. March 17, 2000: The owner reported that Indian Point Unit 2 in New

> York had been forced to declare an emergency condition and shut down after a

> steam generator tube failed and resulted in approximately 19,197 gallons

> leaking from the reactor coolant system. The owner stated "Preliminary

> analysis indicates that the cause of the tube failure is primary water

> stress corrosion cracking (PWSCC)" [i.e., ageing].< snip

>

> On this occasion the root cause was a poor design of steam generator, poor

> material for the tubing, unnecessary delays in the replacement by the

> operator and issues with the SG inspection work both on the part of the

> operator and

> also the NRC.  In terms of Age these SGs had probably far exceeded their

> realistic lifespan.  As mentioned earlier these were the last SGs of this type

>

> (Westinghouse Model 44) to be replaced in the US.  Some had been replaced as

> long ago as

>  18 years previously at Turkey point.  The last (before IP2) were replaced

> in 1996. So rather than failing before they should (based on current

> knowledge) these

> SGs have probably exceed the predicted lifespan for these components.



--- but steam generators are all affected by ageing. salem unit 2 is another

example. perhaps what Dave is saying is that NRC should do its job and require

steam gen replacements before they blow up ---



>

>

> See comments for item 2 at Catawba Unit 1.  I would be interested to know

> whether the investigation into the fault on unit 1 on March 14 had been

> completed and whether any recommendations had been made about reviewing

> whether neoprene had been used in this application on unit 2 (or other

> reactors)

> and if it was already planned to check for this problem before this fault

> occurred.

>



--- don't know ---



>

> snip > 5. September 12, 2000: The owner reported that Oyster Creek in New

> Jersey had been forced to shut down because a system needed to provide

> containment integrity had failed a periodic test. The owner determined "The

> cause of the degradation in Secondary Containment was age-related

> degradation [emphasis added] of the automatic ventilation exhaust valve

> seals."<snip

>

> This at least appears to be a relatively straightforward case of ageing.  No

> suggestion of the incorrect use of materials, poor design, poor maintenance

> etc.

> ----- Oyster Crack is a case of general aging. That plant (no offense meant to

> Exelon radsafers) scares me to death.---



>

> snip > 6. September 27, 2000: The NRC reported that Diablo Canyon Unit 1 in

> California had automatically shut down after an electrical transformer

> failed and interrupted the supply of electricity to the reactor coolant

> pumps. The NRC stated "The licensee's evaluation concluded that a center bus

> bar overheated at a splice joint, which caused a polyvinyl chloride boot

> insulator over the splice joint to smoke. Eventually, heat-induced failure

> of fibreglass insulation on adjacent phases resulted in phase-to-phase

> arcing" [i.e., ageing].<snip

>

> While the final result may have been "heat induced failure of fibreglass

> insulation"

> that Dave defines as ageing, the root cause of the incident appears to

> centre on the

> centre bus bar overheating at a splice joint.   It is not clear what caused

> the bus

> bar

> --- I thinkn both you and Dave are correct.---



> snip > 7. February 16, 2001: The owner reported that North Anna Unit 2 in

> Virginia had been forced to shut down due to leakage exceeding ten gallons

> per minute from the reactor coolant system. The owner determined "The cause

> of the stem packing material failure below the lantern ring is attributed to

> ageing" [emphasis added].<snip

>

> Again an example where it would appear that there were no other factors

> involved.

> No suggestion of improper materials, design, installation or maintenance.

>



--- good. And Anna is one of the plants Dave likes ---



>

> snip > 8. April 2, 2001: The owner reported that San Onofre Unit 3 in

> California automatically shut down after an electrical breaker failed and

> started a fire. The failed breaker was reportedly 25 years old and scheduled

> for inspection next year. The owner "will implement modifications to

> appropriate preventative maintenance [emphasis added] procedures to address

> the apparent failure causes."<snip

>

> This is a difficult incident to asses based on the available information.



--- well, just trust us ;-) ---



>

> As the

> response of the operator is to "implement modifications to appropriate

> preventative

> maintenance procedures" coupled with the fact that the fault occurred 12

> hours after

> restart following a refuelling outage, it is possible that this was a

> "maintenance induced

> failure" rather than ageing. I would be interested in further information if

> it is available.

>



---- We got San O. people on this list - speak up guys and gals ! ---





>

> snip > 9. April 23, 2001: The owner reported that South Texas Project Unit 2

> in

> Texas had been forced to shut down after actions in the plant's electrical

> switchyard tripped all three pumps supplying cooling water to the main

> condenser. The pumps stopped running after workers took one electrical

> circuit out of service thinking that a backup circuit was available to take

> up the load. However, the backup circuit was also out of service because an

> electrical breaker had remained opened after workers tried to close it. The

> breaker's failure was attributed by the owner to "accelerated wear of the

> components" [i.e., ageing].<snip

>

> In this instance although the operator has identified "accelerated wear of

> the

> components" of the failed circuit breaker, it was not the failure of the

> circuit

> breaker that caused the shutdown, but rather issues relating to work

> planning

>  and work control.  The plant was operating satisfactorily without the

> faulty

> circuit breaker in service.  The plant tripped when an operating electrical

> circuit

> was removed from service without confirming that the alternative supply was

> available and healthy.  In addition it is also not clear what had caused the

> accelerated wear of the components in the failed circuit breaker.  I don't

> believe that you should consider the failure of items of plant and equipment

> due to poor design, manufacture, installation, maintenance or operation as

> " age related" failures.  Plant and equipment can fail rapidly if it is not

> designed

> for the purpose in which it is used.    If you buy a car and some of the

> components

> in the engine have been manufactured from mild steel and not hardened steel,

> these components fail after only a few thousand miles due to excessive wear

> is this

> an age related defect.   What if you buy a new home cinema system and have

> it

>  installed inside a cabinet so that its major components are not visible.

> If the installer

>  does not allow sufficient room around the components for the heat to

> dissipate and

> be removed then they may fail soon after installation due to overheating.

> Is this an

> age related defect?  You buy a new car and never have it serviced, routine

> oil

> changes etc.  The engine fails after two or three years due to excessive

> wear, is

> this an age related defect? If you use a crane rated for 5 tonnes to lift

> 7.5 tonne loads and it fails after a number of lifting operations due to

> excessive

> wear of the components is this an age related defect?

>



--- sorry, you lost me somewhere in this one. ----



>

> As it is getting late I'm not going to continue looking in detail at the

> remaining

> incidents.  There are however still some points I would like to discuss.

>

> Oxidation of metal in piping and pumps.  I believe that it is inappropriate

> to attribute all oxidation in pumps and piping to age.  The major factor is

> the

> chemistry of the fluids passing through these items.  Poor plant chemistry

> can  greatly accelerate the rate of oxidation on these systems entirely

> independently

> of age.  Poor chemistry can result in very rapid failure of some types of

> material

> used for these purposes.  If the fault occurred in a plant that operated

> within the EPRI

> chemistry guidelines then there may be a case for suggesting ageing as the

> cause.

> If the plant has consistently demonstrated poor chemistry control then it is

> this rather

> than ageing that would be cause.

>



--- I'd say "poor chemistry accelerates ageing ----



>

> If the manufacturer revises its guidance on the maintenance or replacement of

> components then this should be accepted as the expected life of the

> component. If the component fails after it has been in service for a period

> longer than

> that recommended by the manufacturer then I don't believe that this can be

> attributed to premature failure of an aged component.  Rather it is the

> failure of the

> operator to implement the recommendations of the manufacturer.

>



--- sorry, old is old. ---



>

> I was surprised to see the use of the phrase "running to failure".  Was this

> phrase

> used by the operator?  Is this a practice commonly used in Nuclear Plants in

> the US?



--- don;t know ---



>  I would be surprised if it is.  I'm not sure if what was meant by this

> phrase was the  use of a system I know as "condition monitoring".  In this

> system

> measurements are taken of things like vibration of bearings, current used by

> pumps when operating etc. when the items have been recently installed or

>  maintained.    Periodic measurements are then taken of the parameter of

> interest and these are then used to monitor the performance of the item of

> equipment.  Equipment is then only maintained when the monitoring data

> indicates that a fault is developing.  The fault should be identified long

> before the equipment is likely to fail.  This allows the operator to reduce

> the

> number of

> routine, periodic maintenance activities.  This reduces the overall

> maintenance

> requirement for the plant.  In doing so it also reduces the doses received

> by

> personnel working at the plant (at last a HP reference).  Crucially from a

> safety

> perspective it should reduce the number of instances of "maintenance induced

> failure".  This occurs when fully functional/operation plant and equipment

> is

>  taken out of service for periodic maintenance, whether it actually needs to

> be

> maintained or not.  It is then returned to service and fails due to some

> problem that

> was caused during the maintenance work.  If items are actually run until

> they fail,

> instead of run until there are indications that maintenance is required,

> this would

> present large problems for the operator.  There is a much greater potential

> for loss

> of revenue if a plant shuts down unexpectedly than if the shutdown is

> planned for an

> appropriate date.  Where the shutdown is planned all the facilities,

> personnel, spare

> parts, specialist contractors etc. can be made available and the work can be

> completed in the shortest possible time.  If the equipment fails

> unexpectedly then

> replacement parts might not be available, it may occur after the majority of

> personnel

> have finished work for the day, even worse it may occur at a weekend.  This

> would

> delay the commencement of any repair.  There may be a requirement for

> specialist

> contractors these would require time to make themselves available etc.  On

> top of

> all of this a significant unplanned event could lead to the involvement of

> NRC

> inspectors.  They could significantly delay the start up of the plant.  E.g.

> the time

> taken from failure of the Indian Point SG to return to service was

> considerably longer

> than could have been achieved if the SGs had been replaced as part of a

> planned

> outage.

>



--- basically yes, especially about IP. Was NRC screw up and short-sighted

chasing after profits and cutting safety corners by the owners. Lots more wrong

at IP besides the steam gens ---



>

> And finally,

>  snip > Nuclear power plants generate revenue by producing electricity.

> <snip

> Absolutely, and to maximise their revenue they require the longest Breaker

> to Breaker runs possibly.  This can only be achieved through very high

> standards of maintenance.



--- yes indeed. by they gamble by cutting corners ---



> Recent years have seen record after record set for the

> longest

> breaker to breaker runs of each different reactor type in the US.

>

> snip>If their owners are unable to properly maintain the equipment needed to

> make them

> money<snip

>

> Having spent the majority of the report emphasising the effects of ageing

> why has

> Dave chosen to bring up the issue of maintenance?

>



--- don't know,e xcept of course the two inter-relate---



>

> snip>why should the public believe that they are able to properly maintain

> the equipment needed to make us safe?<snip

>

> What evidence does the UCS have that indicates that they (the US power plant

> operators)

> are unable to properly maintain the equipment needed to make the US public

> safe?

>



--- ask Dave! ----



peace

norm



>

>  Regards

>         Julian



--

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