ML20140G781
| ML20140G781 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde, 05000000 |
| Issue date: | 05/06/1985 |
| From: | Reed G Advisory Committee on Reactor Safeguards |
| To: | Ebersole J Advisory Committee on Reactor Safeguards |
| Shared Package | |
| ML20140B723 | List: |
| References | |
| FOIA-86-45 NUDOCS 8604030582 | |
| Download: ML20140G781 (12) | |
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'o UNITED STATES P
NUCLEAR REGULATORY COMMISSION n
.y I
ADVISORY COMMITTEE ON REACTOR SAFEGUARDS WASHINGTON, D. C. 20665 pgAREDit)R MTERNE
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May 6, 1985 i
l MEMORANDUM FOR:
J. C. Ebersole, Chaiman Palo Verde Subcommittee FROM:
G. A. Reed, ACRS Membe,
.g REFLECTION ON PALO VERDE SUBCOMMITTEE MEETING OF f
SUBJECT:
APRIL 26, 1985 It would appear that most of the issues in abeyance related to the ACRS letter of December 15, 1981 have been satisfied; and perhaps also most of your questions.
My evaluations from the meeting and plant Unit #2 tour are as follows:
Bechtel (The AE) and APS have created a spacious overall 1.
facility and the individual units have much above average in containment space, laboratory space, spent fuel handling Layout and arrangement of equipment is very good.
space, etc.
Excellent permanently installed walkway access inside contain-j Compartmentalization is good from security ment exists.
viewpoint, but maintainability inside some compartments is 1
only good - mostly caused by pipe-whip structures or seismic
'i restraints.
The state of the Unit I toured was that it was essentially 2.
Also much of the complete except for insulation and painting.
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hydrostatic type testing is complete. There were not many workers in evidence on the unit and operating personnel seemed to be deployed for the most part elsewhere on higher priority work of Unit 1.
Housekeeping and appearance throughout Unit
- 2 was excellent. No graffiti was evident -- and since final painting has not been performed, it is obvious that this
- i aspect has been unusually well controlled.
I saw no installed equipment, piping, etc. that I could 3.
Even the criticize from materials, support or other reasons.
charging pumps which were stated earlier not to have suction stabilizers did actually have them quite appropriately in-stalled - except I would have used a larger pipe size between the suction stabilizers and the pump blocks.
My quick brush with operating personnel indicates they are 4.
natural ability selected for operations and perhaps also for maintenance I would judge the training activity and people I did wander in on one or two qualification to be good.
classes in session and the activity seemed good.
8604030582 860311 PDFt FOIA ATTACHMENT 1 SCOTT 86-45 PDR
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J. C. Ebersole, Cha.rl PREPARED FOR INbNAl. COMMITTE l
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The only problem I have with the Palo Verde units is the "no frills" basic conceptual design of safeguards systems. My
' tour examination tells me the " start up", or third auxiliary boiler feed pump is not classifiable as a third auxiliary feed '
pump for safeguards, since it lacks security protection and is with its suction and discharge piping etc. located very much uncompartmented in the open area of the ground floor of the turbine building. Therefore, Palo Verde core melt protection (safeguards) systems boil down to this:
i Two (2) Aux Boiler Feed Pumps & T.ains (one steam -
One elec.)
Two (2) HPSI pumps and trains a
Four (4) accumulators 1
1 Two (2) LPSI pumps and trains Two (2) steam generators with atmospheric dumps Pressurizer Auxiliary Spray w)ith two (2) parallel enabling valves and three (3 44 GPM positive displacement pumps - pumps used for other service and which may not be committed beyond one or two i
available.
Two diesels at about 5000 KW each.
For the trends o_ today toward more redundancy and options to effect f
core cooling in the most serious and likely situations of SBLOCA - tube l
rupture; this stack up of systems is the most " lean" I've seen - cer-A further complication is that several enabling tainly no frills.
valves are in the normally closed position and with series vs. parallel a
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Personally, I would study these valve arrangements more arrangements.
carefully to try to cut down on the number of closed valves.
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On the positive side for these lean systems, I feel APS personnel will run a " tight ship" on surveillance and maintenance; that is, the present organization. Also the installations of these lean systems appear as quality jobs.
Seems to me the way to evaluate this " leanness" combined with no backup mode of primary depressization by PORV's, is to ask for a partial plant specific PRA for Palo Verde, and that this PRA be performed on a fairly high priority'sch'edule, say within one year.. I believe further eval-uation of core melt (safeguards) systems is appropriate for Palo Verde, and if Palo Verde isn't on the A-45~nine plant list for risk of cort melt evaluation it should be.
I don't believe the other contributors such as fire, seismic, wind, flood, etc. need to be looked at - only the PRA of the safeguards systems.
One should keep in mind that the " leanness" of safeguards systems is an NSSS designer responsibility --- and this only serves to remind us that 3
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J.C.Ebersole,Ck.g 3
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this " sole licensee" utility structuring of the NRC should shift focus to NRC certification of NSSS designs and designers.
e From a operational viewpoint --- not core melt risk related --- I found '
the pressurizer safety valve installations likely to give Palo Verde some substantial lost production time. The four safety valves are located at the top of four pipes rising almost vertically off the pressurizer --- with no water loop seals. These pipes will certainly fill with pure hydrogen, against which even the best of safety valves will proably leak. Then with leakage and microscopic wire drawing --
What will be tolerable? Here again. I got the more leakage, etc.
feeling that systems design for Palo Verde is more vintage 1970 than 1980 as advertised.
cc: ACRS Members 1
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b 29 5 E NG AUGUST 9-11,1984 WASHINGTON,D.C.
The 292nd meeting of khe Advisory Comittee on Reactor Safeguards, held at 1717 H Street, N.W., Washington, D.C., was convened by Chairman J. C.
4 Ebersole at 8:30 a.m., Thurday August 9,1984.
For a list of attendees, see Appendix I.
D. Okrent, G. A. Reed,
[ Note:
andP.G.Shewmendidnotattendthemeeting.]
Chairman J. C. Ebersole noted the existence of the published agenda for He r.oted that this meeting, and identified the items to be discussed.
the meeting was being held in conformance with the Federal Advisory Comittee Act and the Government in the Sunshine Act, Public L and 94-409, respectively.
the public portions of the meeting was being taken, and would be available in the NRC's Public Document Room at 1717 H Street, N.W.,
i Washingten. D.C.
Copies of the transcript taken at this meeting are also available for purchase from Free State Reporting Inc., 99 Cathedral
[ Note:
l Street, Annapolis,MD21404.]
i I.
Chainnan's Rep::rt (0 pen to Public) l R. F. Fraley was the Designated Federal Official for this
[ Note:
portion of the meeting.
Chairman J. C. Ebersole indicated that the Comissioners granted 4
a full pcwer operating license to the Grand Gulf huclear Plant on l
31, 1984 He also noted that at an August 2, 1984 July Comission meeting, the Diablo Canyon Nuclear Plant was given a license for full power operation to be effective August 15.
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Falo Verde Nuclear Generatino Statien Units 1, 4, and 3 (0 pen to II.
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Pubitc)
A. Wang was the Designated Federal Official for this
[ Note:
portionofthemeeting.)
P. Narbut Project Inspector, Region V, indicated his plan to discuss the following topics:
Significant constructi.on deficiencies o
Effectiveness of QA program e
Status of preoperational test program i
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He noted that the Palo Verde management has submitted a large number of 10 CFR 50-SS(e) reports.
They appear to have a low threshold of reportability of items which have potential 1
ATTACHMENT 2
AUGUST 9-11,1954 MINUTES OF THE 292ND (" MEETIhG indicated that their willingreess to report significance.
He events is good, and the quality of their evaluations is pnerally technically sound and thorough. He stated that the App 1' cant has use of outside expertise in evaluations when In general, their actions were properly expanded in made proper required.
He the technical 14rea to include all units (see Appendix IV).
did point out, however, that the Staff believes some improvement is required in identifying the root causes of reportable. items.
He speculated that the deficiency may involve a less than orderly design review checkoff or an individual evaluator who just does an inadequate review.
J. C. Ebersole noted that the Applicant is apparently good at identifying the roc _t cause of failures during the preoperational test program, but should have found them before the preop test.
He stated his belief that the preop test program ought to be The Comittee discussed the confirmatory and not exploratory. occurred during the in-plant large number of failures whichComparison was made of the failures of the preoperational test. reactor coolant pumps at Palo Ve-de with the materials in diesel generators at Shoreham.
C. P. Siess suggested that these were both instances of inadequate or improperly qualified
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equipment or improperly tested equipment such that deficiencies were not discovered until tested on the site prior to operation
. J. Jackson, NRC Qualifications Branch, noted that of the plant.
the reactor coolant pumps at Palo Verde were subject to C. P.
approximately 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br /> of testing prior to installation.
- I Siess asked if the pump had been tested under the same flow conditions seen at Palo Verde.
J. Ja:kson indicated that it was tested under runout conditions with maximum flow that would be C. Michelson asked if the Staff was Palo Verde.
expected at J.
inferring that each of the pumps was tested for 150 hours0.00174 days <br />0.0417 hours <br />2.480159e-4 weeks <br />5.7075e-5 months <br />.
Jackson indicated that only the design pump, one pump, was tested.
J. C. Ebersole asked if the Palo Verde Plant was designed to sustain an event such as an overfilling of the steam generator characterized by filling of the steam lines up to the turbine C. Michelson wanted to knew if the system had been stop valves.
tested for dynamic loading with the steam pipes full withcut any manual adjustmer.ts to the spring hangers.
The Applicant indicated affirmatively.
The Comittee discussed several significant construction deficiencies dealing with defective structural bolting, faulty electrical terminal lug crimping, and main steam isolation and feedwater isolation valve problems.
P. Narbut indicated that the Staff has found that the QA program at Palo Verde is generally effective in construction activity
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control by the contractor.
Hardware, in general, is built per and the records of the hardware construction are drawings They have a better than average quality of work done adequate.
The Staff in the field in the electrical and mechanical areas.
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' INUTES OF THE'19thu ACRntaianu - -
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I has some reservations at this time, however, regareing the of subcontractor work controls.
This could done this year was not as good as the one last year Combustion Engineering t G. McCoy, Assistant Project Manager, explained that a post demonstration test was perform N
reactor coclant pumps, the CEA shroud, and the RTD therma 1 to August 5;' 1984 h
He indicated that af ter review of the preliminary data, 9
f acceptance criteria established for the cperating parameters.
M.
found that the D
been W. Carbon asked for a summary of the faults regarding the rea G. McCoy stated that the reactor coolant pumps d by used at Palo Verce were designed by KSB in Germany coolant pumps.
Combustion Engineering,ior to installation at Palo Verde, these Newington Facility.
Pr f
pumps were tested for about 500 hours0.00579 days <br />0.139 hours <br />8.267196e-4 weeks <br />1.9025e-4 months <br />, and with the exce hi h minor mechanical fastening problems, and hydraulic problems w C.
the pumps successfully passed all tests.
Michelson asked if there are other pumps of this were rectified, U.S.
anywhere else.the Green County Purp manufactured by KSB fo was very similar to the Palo Verde pump.
C. i41chelson indicated that he thought theseD about 800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br />.
pumps were in routine use in Europe.
hydraulics are slightly different in nuclear pl pumps, which are of mixed design.
C.
Michelson suggested that the European applications had censiderably European tolerances and the clearances were trismed for the Palo Vero pump because of the need for mcre flow. European p impeller.
J. C. Ebersole poirted out that the Combustion Engineering S 80 Design is totally dependent upon an ab There is maintain a themal driving head to the secondary side.
i no way to remove decay heat except through the secondary s under ccnditions of a long term ac power outage, the pump seals will leak creating a small LOCA w He suggested that Me destroy the temperature driving head to the secondary side.
asked what the characteristics of the reactor coolant pumps are In the prolonged absence of ac power regarding the de leakage that can be expected.
pumps at Palo Verde are the first pumps J. C. Ebersole means of providing charging flow to the seals.
suggested the scenario of a total blackout with no ac po G.
He asked how CE provides flow to the seals.
Davis admittee that this would be a situation where the no diesels.
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not be seal injection flow. seals would still maintain their i 3
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AUrdiST 9-11.'1984
. MEUTES OF THE 292ND {" MEETING t
J. C. Ebersele pressed for a quantitative estimate of of time.
the amount of time involved and the accompanying leak rate, since it was important to the question of preservation of the J. Jackson overtemperature driving force to the secondary side. indica other CE plants have been tested for a 50 hour5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br /> station blackout.
That is the type of seal being discussed here.
G. McCoy explained that the damage to the reactor co'olant pumps involved the following:
I Broken impeller vanes or two of the pumps e
e Loose diffuser bolts Broken diffuser bolts and some limited cavitation damage on e
the diffuser He discussed instrumented tests done at CE's Newington facility and design changes that were made to the pumps to substantially He noted reduce stresses during runout operating conditions.
that definitive testing of instrumented impeller blades confirmed that thicker impeller blades made a measurable difference regarding static and dynamic loads on the. impeller blades in the critical area.
I J. C. Ebersole asked about the ultimate potential effects of G. McCoy having extensive damage in the upper guide shrouds. ind but are basically to the course of operation of the plant,If a crack were to propagate provide guidance during refueling.is conceivable that many of the guidance in the shroud, it fingers might simultaneously fail, and prevent insertion of a number of centrol element assembly (CEAs) (stuck rods).
He incicated that structural and vibration testirg was done to Tremendous cross flows investigate the stuck rod possibility.
were found in the two bank region, and it was cetermined that the frequency of these tubes corresponded to the driving natural To design away from that frequency of the reactor coolant pumps.
i frequency, the plates were moved upward to increase the frequency of the tubes above that of the driving frequency.
G.
McCoy explained that thermal wells which contain the resistance temperature, detectors (RTD) in the primary loop had failed due to fatigue caused by high runout flows which caused 1
He indicated that the resistance temperature vortex shedding.
detector thermal wells in the cold leg were beefed up to be sore rugged, and tapered to reduce the effects of vortex sh l
the tip.
thermal sleeves, G. McCoy indicated that these thermal sleeves l
It were removed from all CE plants except for the charging line.
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was found that the prcblem was caused by vibration and rctation i
Since removal of the thermal sleeves, of the thermal sleeves.
The there has been no need to pursue the problem any further.
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.,M!NUTES OF THE 292ND ACRS MEETING A p uu y-aa.. m,
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j; failure to start of low pressure safety injection pumps was attributed to an overcurrent trip. When current was applied to the motor, the pump began to rotate causing a larger current flow through the motor. This intennittent complex problem was solved by interchanging a higher horsepower containment spray pump acto?,
for the original low pressure safety injection pump actor.
Ne indicated CE's belief that the larger diameter shaft associated with the highePhorsepower motors prevented the shaft deflection 4
that resulted eventually in the overcurrent trip.
J. E. Ebersole pointed out that the larger motor resulted in a more rigid shaft, and a more rigid shaft was the solution to the problem.
G. McCoy agreed.
L. Crocker, NRC, indicated that Palo Verde is better prepared from' an onshift operating experience point of view than Diablo Canyon (see Appendix i).
He indicated that Arizona Public Service Company (AFS) will have an independent STA on shift.
F.
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Remick asked regarding the status of Palo Verde training programs with respect to INPO accreditation.
E. Van Broch, APS, indicated that the program ~ would be completed in the next two years.
T. Marsh, NRC, discussed the single failure of the pressurizer spray system. This plant does not have PORVs. As an alternative means to depressurize the plant for events where the steam generators are not available, a ' safety grade pressurizer spray system which uses basically the safety grade charging system has been designed as an alternative means to depressurize.
He indicated that the Staff is concerned regarding failure of the single available valve which provides water from the charging system to the sprays.
He noted that while there is a safety grade solenoid on this valve, there is a ncn safety grade air supply to this valve. He indicated that the solution proposed by APS is to put an isolation valve upstream of the single valve (may stick open) to guarantee closure and flow to the pressurizer spray. This isolation valve would of course, have to be properly qualified.
The Conw.ittee discussed the vulnerability of the single valve sticking in_ an open position, diverting and preventing flow to the spray system.
Loss of power to the solenoids or loss of the air supply to the valve would normally cause the valve to fail closed under spring pressure.
J. C. Ebersole notea that it is not possible to get water into the primary system when ac power is unavailable. He pointed out that other designs have developed deoicated diesels, or hydraulic pumps driven by mechanical engines, to supply fluid when needed when there is loss of ac power.
He wondered why the Staff had not discussed the rationale for setting a requirement for this extremely critical function for the CE design.
G. Davis, CE, suggested that the situation postulated was a multiple failure
'E scenario involving a station blackout.
He suggested that this
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will be part of the design basis for Palo Verde and it is a concern for every nuclear plant in the U.S.
T. Marsh indicated that every plant has accumulators, and if the plant has a 5
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, MINUTES OF THE 292ND ACRS MEETING g
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depressurization capability, one may be able to g He recognized that this plant has no Italy ar.d Switzerland.
capability of depressurizing other than opening the atmospheric dump valves and steaming the steam generators.
By taking.-
advantage of the contraction resulting from blowing off some of J.
the secondary coolant there would be some depre existence of the thennal driving head to produce a lower pressure i
in the secondary.
6.
Mazetis, MRC, discussed the use of symptomatic generic procedures to deal with the multiple steam generator tube failure He explained that once the multiple steam generator situation is identified, the operator is instructed to isolate scenario.
J. C.
the worst steam generator from the viewpoint of of which steam generator to isolate.one would steam or allo T.
generator or the one with the smallest leak to the condenser. tub Marsh mentioned a eultiple3800 Class CE reactors assuming th J. C. Ebersole and D.
steam generator and continuou1 steaming.
T. Marsh A. Warc expressed interest in the integral analysis. d has been-indicated it wat identified as report number CEN 239 anIn an l
sent to the ACRS.
to an individual Marsh indicated that the maxieum offsite dost was reported at 200 rem to the thyroid assur.ng a p
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iodine spike.T. Marsh explained thet primary coolant continued to be lost out of the break at a rate so as not te overf tenninated.
t generator.
the primary system depressurized.
ReacterOperatingExperience(0pentoPublic)
I III.
R. Savio was the Designated Federal Official for this
[ Note:
portionofthemeeting.]
E. Rossi, Events Analysis Branch, IE, (presented two group recent significant operating events see Appendix VI).
He indicated that Staff members were prepared to present detailedpartic of seven events that IE thought He noted that the Staff was siso prepared to oake a description special presentation on a very recent event, a total loss of all interesting.
ac power at Susquehanna 2.
E. Rossi explained that an automatic scram was i Six of 37 cable-driven 23, 1984, prestressed concrete reactor vessel.
control rod pairs failed to insert on trip and were manually driven in within approximately 20 minutes cf the automatic scram.
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He noted that high moisture content preceded this event and a previous similar event which incurre
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EBER50LE 4/13/85 AGENDA ITEMS FOR PALO VERDE SUBCOMMITTEE MEETING APRIL 27,1985 - PHOENIX, AZ - SOMEWHERE NEAR AIRPORT
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I Planttourbythosewhowish(notJCE)aftermeeting.
Meeting in morning.
I have a plane out to return about 4:00 P.M.
Suggest start at 8:30 A.M., close for lunch, and subsequent field trip about 12:30 P.M.
TOPICS A.
Current Plant Status - Projection of work to be completed before 1.
escalation to full power.
2.
Full Power Escalation Program Chronological List of Significant Unexpected Findings during Hot 3.
testing and 54 Power Testing.
Include all Valve Malperfonnance Findincs.
In view of the extreme reliability required of the main and auxil-4.
iary feedwater system:
Describe why applicant believes he will not experience a.
those cases of complete loss of feedwater at PWRs which have actually occurred, Discuss anticipated frequency of use and frequency of real b.
need of auxiliary feedwater system.
As a topic to focus on valve reliability, provide a discussion of 5.
the isolation valves for the chemical volume and control system.
Include:
Reading the specifications for the valves as they relate to a.
power supply, trip signals, and design basis to close on open discharge at full system pressure.
Describe arguments for ability to close while delivery faulted b.
,, flow.
If only analytical, describe analysis.
If by test, describe test.
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- If outboard piping fails and flow is not intercepted until interiororexteriorvalveismanuallyclosed(ifitcanbe) c.
describe ultimate consequence in context of equipment damage in auxiliary building and core damage, if any. If core damage occurs, define off-site dose.
B.
Discussion with Operating Staff Describe (on a personal basis) the most critical accident situation Name about six of I.
you are required to mitigate by operator action.th~ese and include service water, less of component cooling water, and loss of DC What will be the visible effects of power to the " safety" systems.
loss of the two most critical DC system in respect to control room 1
indications.
Discuss and express your view as operators, having been handed a 2.
given engineering design, your opinion as to whether you have adequate assets (or perhaps too much infomation) to perfom the I
above emergency functions in respect to the following areas:
adecuate (and not too complex) instrumentation for the a.
initial conditions l
an appropriate degree of automatic response of equipment b.
Reasonably simple accident recovery procedures c.
d.
Adequate time to perform the recovery function Instrumentation which will accurately confim or deny that e.
proper recovery action has occurred, and Adequate prerogatives to reverse corrective actions in case f.
human error has occurred.
Describe the difference, as you understand it between direct and 3.
indirect instrumentation indications.
Include both process parame-ters (pressure, temperature, etc.) and equipment functional perfor-List the " indirect" indications for which 'some mance indications.
confimatory evidence of correct actual system or equipment response must be invoked.
There are two broad classes of safety-related systems in the plant.
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One.of. these is the specialized set of systems designed to mitigate i
the classical "LOCAs " What are the "others?" Which do you consider to be more important to safety?
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3-Are How did you determine the existence of the "other" systems.
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all of these systems on something equivalent to "Q" list?
In your plant, when one of these "other" systems fail, does an 6.
operations disturbance occur which requires even more rigorous performance of the residual equipment performing the same critical function?
If the residual equipment is on standby ()an example might beand the first 7.
service water or component cooling pumps failure demands auto-start of the backup equipment:
Do you have redundancy after the first failure (as you a.
do with the on-site diesel generators)?
If you do not, how much time do you have, in the most b.
critical cases, to restore the needed function in case the standby system fails to respond to the start-up challenge?
Redundancy is always provided in the ECCS systems which c.
How do you rationalize the absence of respond to a LOCA.
redundancy (if such cases exist) in the light of critical service system functional failures which will be much more frequent than LOCAs?
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