Re: lochbaum on nuke plant aging

["julian ginniver" <julian.ginniver@lineone.net>]

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)



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?



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".  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".



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".  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.  Are the plants full of ageing components that

are

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

operating at peak reliability?  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.



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

surname) 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?



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

or

incident 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.  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.



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?  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?



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.



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.





snip > 4. March 27, 2000: The owner reported that Catawba Unit 2 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



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.





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.



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 to overheat.  It could possibly have been poor installation of the

splice joint?  I

don't believe this fault can be attributed to ageing unless it can be

demonstrated

that the overheating of the bus bar was an age related fault.  The

fibreglass

insulation that failed and caused the arcing, failed because it was subject

to the

higher than planned temperatures resulting from the overheating bus bar.

Place an

average human in Death Valley and without any intervention they would

probably die.

Would this be attributed to death due to ageing?





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.





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.

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.





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?



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.



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.



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?  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.



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.  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?





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?



 Regards

        Julian





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