ML20064L560
| ML20064L560 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Brunswick |
| Issue date: | 07/06/1982 |
| From: | Elzeftawy M, Wolf T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Michelson C NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| Shared Package | |
| ML20064E577 | List: |
| References | |
| FOIA-82-389 NUDOCS 8207120140 | |
| Download: ML20064L560 (12) | |
Text
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'o UNIT 5D STATES
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g NUCLEAit REGULATORY COMMISSIO.N 3
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WASHINGTON, D. C. 20555 Y J4,o$
JUL 6 1982 MEMORANDUM FOR:
Carlyle Michelson, Director Office for Analysis and Evaluation of Operational Data THRU:
Stuart Rubin Q
Office for Analysis and Evaluatio NN of Operational Data FROM:
Medhat El-Zeftawy Office for Analysis and Evaluation of Operational Data Thomas R. Wolf Office for Analysis and Evaluation of Operational Data
SUBJECT:
SITE VISIT / MEETING NOTES - BRUNSWICK STEAM ELECTRIC PLANT - MARCH 24, 1982 1.0
SUMMARY
1.1 Objectives At the request of the Office for Analysis and Evaluation of Operational Data, S. Rubin, M. El-Zef tawy, and T. Wolf met with personnel from Carolina Power and Light (CP&L) at their Brunswick Steam Electric Plant (BSEP) located in Southport, North Carolina on March 24, 1982.
The major objectives of this site meeting were:
a.
Gather firstFand experience information on moisture intrusion in pur-portedly enviro'nmentally qualified electrical equipment; b.
Discuss operational experience concerning non-marine growth fouling of small diameter pipes with particular attention focused on those lines in systems associated with the raw water supply of the ultimate heater sink; and Provide M. El-Zeftawy and T. Wolf their first opportunity to examine c.
in person an operational boiling water reactor facility including structural and equipment layouts and equipment and personnel operating conditions.
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1.2 Findings
The principal findings of this site visit were:
Moisture induced f ailures of supposedly qualified electrical a.
equipment at BSEP have been caysed by three main pathways:
(1) Moisture entering the equipment through unsealed conduit,_.;
i.e., conduit serves as a conducting pipe line; (2) Moisture entering the equipment at sealed but not water-tight conduit fittings; and (3) Moisture entering the equipment passed poorly re-sealed equipment cover plates or doors fo' lowing maintenance or testing activities.
BSEP. personnel have undertaken several corrective and preventive b.
measures to help eliminate the moisture intrusion problems including:
(1) Additional personnel training; (2)
Revised maintenance practices; (3) Additional equipment sealing particularly internal and external to equipment penetrations; and Contracted with their Architect / Engineer (A/E) to study the (4) problem further and recommend additional or alternative preventive measures.
BSEP personnel believe IE Bulletin 79-01B covered only initial c.
They felt it did not equipment qualification and installation.
address the need for, importance of, or adequacy of equipment main-tenance surveillance controls.
Non-marine growth blockage of small diameter lines at BSEP has d.
never been a problem.
As a precaution against such an occurrence, however, BSEP has taken several steps to minimize the potential for I
sediment buildup.. Included are:
To the extent possible, all small lines tap off of the top of the (1) process pipe; Instrumentation is located at the top of a vertical run of pipe (2) with drain valves and lines located at the bottom of these vertical runs; For pump seal protection, cyclone separators are provided in the (3) seal injection lines of the raw service water pumps and the circulating water pumps.
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1.3 Actions Engineering evaluations of several recent BSEP submitted licensee event reports (LERs) which involved equipment environmental qualificationIt is antic and small line blockage are being prepared.
evaluations will contain several points which will be suitable for trans-mittal-to both NRR and IE for their infonnation and utilization in ongoing equi,pment qualifi_ cation and small*1ine blockage studies.
2.0 DETAILED DESCRIPTION
2.1 Background
Over the years that CP&L has been operating commercial nuclear power stations, they have reported to the NRC numerous occurrences of safety-Primarily '
related equipment failures resulting from moisture intrusion.
involved are electrical compenents located in high humidity /high temperature areas of the reactor building outside primar The results importance of equipment qualification have been occurring.
of these studies have included the issuance of IE Bulletin 79-01B
' concerning the environmental qualification of electrical equipment and the formalization of a position covering the continued operation of AEOD nuclear units while further qualific& tion review progressed.
is concerned as to whether or not these staff reviews are adequately addressing, on both a plant specific and a generic basis, the lessons which may be learned from the Brunswick experiences.
Another point of concern within the NRC, including AE00, is the generic implications of flow blockage of prime heat removal systems due to Extensive either marine growth or water source transmitted fouling.
studies have been completed and are continuing on marine growth fouling, especially in relation.to oyster and Asiatic clam' infestations of essential A search of the available data base, however, service water piping systems.
indicates that substantial numbers of LERs have been submitted which equipment problems associated with service water (SW) systems caused by This is especially true for sedimentation"rather than marine growth.A recent LER from BSEP attributed small bore piping.
AE0D the RHR service water system to such fouling of instrument.line::.
is concerned that,suc,h fouling is adequately addressed by both the NRC and the plant licensees since a common mode failure m appropri ately.
As a consequence of these concerns and because of the experiences which BSEP has had with both environmentally qualified equipment and service water line fouling, it was felt that a site visit and meeting with
0 Additionally, a cognizant BSEP personnel was warranted and desirable.
major side benefit of such a visit would be the essential training and Neither had previously experience given to M. El-Zeftawy and T. Wolf.
visited and studied on site an operating boiling, water reactor of the BSEP type.
2.2 Meeting Arrangements and Participants After contacting both the NRC BSEP project manager and the region, On direct site visit arrangements were made through BSEP personnel.
S. Rubin, M. El-Zeftawy, and T. Wolf (all from AE0D March 24, 1982, Reactor Operations Analysis Branch, Reactor Systems 4 - BWR Technology) met with personnel from CP&L at the BSEP site in Southport, North Carolina.
The participants directly involved with this visit are' listed in Figure 1.
Prior to the meeting date, AE0D drafted and sent to CP&L a letter outlining specific informational needs.
Some forty six items were
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noted but due to travel schedule deadlines, a few of these items were not addressed during the visit. A follow-up telecon was held.on April 9,1982 to resolve the unaddressed topics.
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2.3 Site Tour As requested in the AEOD letter, a site tour was included in the visit.
The areas covered during this tour included the Unit I reactor building (excluding primary containment since the unit was operating), the common control building (including the shared main control.oom), one diesel bay ir the common diesel generator building, the common intake structure and miscellaneous yard structures.
(a) the mechanical, electrical, and instrumentation components in the high pressure coolant injection (HPCI), low pressure coolant injection (LPCI),
and combined residual heat removal (RHR) and reactor core isolation cooling (RCIC) pump rooms; (b) the RHRSW pumps, piping and instrumentation; (c) the diesel generator SW piping and instrumentation; and (d) the SW and circulating Also observed were the scram system water pumps, piping and instrumentation.
piping arrangements and the cask handling equipment loading and lifting components, layout, and travel paths.
2.4 Meeting Details After the plant tour, an informal meeting was held to discuss the items This meeting was broken listed in the AE0D information request letter.
into two basic areas:
(a) moisture intrusion into purportedly environ-o mentally qualified equipment with particular emphasis on instrumentation and (b) sediment collection in process piping systems, especially small bore piping associated with the raw service water systems.
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a.
Holsture Intrusion Numerous moisture intrusion related equipment problems have occurred at BSEP. The equipment involved includes, but is not limited to, electrical wiring tennination, boxes and pressure switch instrumentation. The equipment affected is primarily located outside of primary containment in the reactor bui] ding _hasement.(_-17 foot eigvation) HPCI, LPCI, and RHR/RCIC pump rooms.
These pump rooms normally experience an operational environment of about 95'F and 90% relative humidity. Due to system leakage and sump overflow problems, these rooms may also experience some-water accumulation,on their floors.
This water can have a temperature of up to 130*F.
Recently, LERs 81-108/03L and'81-139/03T were received'which described moisture intrusion-related contact corrosion failures of pressure switches associated with the RHR and RCIC systems.
These switches were located in the -17 foot elevation pump rooms and were purchased to withstand an 7 rads.
environment of 290*F,16.2 psia,100% relative humidity and 1.0 x 10 Thus, from an environmental qualification standpoint, these switches should have been able to perfonn correctly in the environment where they were located, Investigation by BSEP personnel into the cause of these failures, along with similar failures noted in the past, has led BSEP personnel to conclude that several mechanisms for such equipment problems are most.likely. These are (seefigure2):
(1) Moisture entering into unsealed conduit connections at cable trays.
These cable trays are located throughout the reactor building. The moisture subsequently condenses within the conduit,and uses the conduit as a piped pathway to connecting equipment such as tennination boxes and instrumentation; (2) Iioisture in the local environment entering the equipment at moisture resistant but not moisture tight conduit connections; and l
(3) Moisture intrusion at improperly sealed equipment enclosure covers.
f In both mechanisms 2 and 3, moisture may condense and enter the connecting l
conduit where, as in mechanism 1, other equipment may be af,fected.
- Also, l
BSEP. personnel believe that mechanism 3 is a result of inadequate main-tenance practices and lack of attention to details during resealing of equipment after calibration rather than from design or manufacturing pro.blems.
This conclusion was based on post maintenance / calibration equipment walkdowns l
which revealed enclosure or cover plate retaining screws loose and/or missing.
In an attempt to resolve these problems, BSEP personnel have decided to Included are:
undertake several corrective and preventive measures.
l Training - Affected personnel are required to take a four-week course (1) which covers electronics and instrumentation and the associated installation techniques and problems. This course is taught by experienced. -
CP&L personnel and includes hands-on training.
e 9
i
-s-(2) Maintenance Practices
. Plant maintenance practices were revised to ensure proper sealing of applicable plant instrumentation housing and/or gaskets by a dedicated plant group.
Figure 3 contains pertinent excerpts from the BSEP Maintenance Procedure Manual which address these revised practices.
(3)
Additional Sealing - All conduit-to-component junction points, both internally and externally, were. sealed on the affected instrumentation.
This was also done to all eiuipment on the seven instrument racks l
located on" the realtor ~ti0ilding outside containment -17 foot elevation which are subjected to the same environmental conditions as the failed equipment (Note:
The instrumentation in the core spray rooms on -17 foot elevation was not included.)
The sealing compound being used is Dow-Corning 732 RTV, a silicon-rubber compound. To date, no sealing problems, including wear-out or end-of-life aspects, have been experienced with this material.
Figure 4 is a sample request and authorization form for this work.
(4)
Additional Study - The Architect / Engineer is working on a possible generic pennanent fix to prevent wetting the racks and associated equipment.
(5)
Manufacturing Changes - Since the equipment failures do not appear to be attributable to manufacturing defects or problems, the manufacturer (Barksdale) has not been contacted.
During the investigation, cognizant BSEP personnel also considered whether the problems identified would have been addressed by IE Bulletin 79-01B
" Environmental Qualification of Class IE Equipment." Their conclusions were that the IE bulletin only requested licensees to examine the pertinent equipment once and verify that it had been installed as required in the installation proce' dure.
They felt that the IE bulletin did not address the need for, importance of, or adequacy of subsequent equipment maintenance controls to assure that the equipment meets all original. installation requirements.
They recognized on their own that proper and sufficient maintenance controls are essential to assure continued equipment quali-fication, operability, and performance.
With respect to the consequences of the failures noted in LERs 81-108/03L and 81-139/03T, the BSEP personnel felt that neither case jeopardized the plant safety.
Involved were pressure switches which had redundant back-ups.
Affected were one trpin of each of the (a) RHR pump discharge pressure pennissive interlocks to the automatic depressurization system (ADS) logic and (b) RCIC system discharge steam line rupture diaphragm pressure sensors.
Due to the redundancy in circuitry design, neither sensor associated function (i.e., permits ADS initiation and isolate RCIC, respectively) was lost.
I b.
Sedimentation Fouling of Small Lines Serious common cause systems interactions failures may result as a l
consequence of equipment fouling due to sedimentation of materials carried in essential service systems such as the instrument air system and the
-7 service water system. The nature of the sediment, however, is of prime importance insofar as the potential for fouling is concerned.
The sediment which is contained in the service water at BSEP appears to be fine, sand-like material.
This fine structure has the charac-teristics of remaining loose and disassociated and, even upon settlement, minimal disturbances such as small-flow rates will stir the sediment up and mix it with the fluid.
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Displaying a sample of the normal service water, BSEP personnel nci;ed to date that while considerable sediment appears.to be contained in the service water, BSEP has not experienced any sediment collection which has caused equipment problems.
The prime equipment fouling source at BSEP is oyster infestation'.
(This problem of marine growth fouling has been addressed in a previous AEOD report.)
Even though no operational problems have been experienced to date, BSEP has incorporated several design and operational items into the systems which could most be affected by sediment buildup. Some of these are:
(1) To the extent possible, all small lines tap off the top of the main process line.
- This arrangement helps minimize heavy particle' carry-over into small diameter lines.
(2) Where possible, all instrumentation connected to th'e small lines is located at the top of a vertical run of pipe.
l.ow point drain lines are included at the bottom of this vertical run primarily for use in calibration since the sensor lines are occasionally purged prior to calibration.
This purging tends to prevent major buildups of sediment in such lines..
(3) - Cyclone separators are provided on a few pumps such as the servi.ce
-water pumps.
These separators are supplied expressly to filter out
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small debris which could be injected into the seals of the pumps and, as a consequence, could cause seal damage and equipment failure.
In cases where heavy sedimentation may be expected, such as in the circulating water pumps, redundant separators are supplied.
These separators are piped up in parallel and help assure that if blockage of one separator does occur, another separator is available.
To date, the cyclone separators appear to be performing satisfactorily.
Blockage
. of one separator has occurred.
This blockage was at the drain discharge nozzle and was' due to oyster shell fragments which were tasily removed by inserting a screwdriver blade into the nozzle and rotating the blade.
l (4)
To help protect the small lines associated with the RHRSW pumps from the effects of the salty service water, the pumps and the associated l
smill piping are purged of the normal salty service after pump testing with demineralized water.
They are subsequently laid up in their standby mode with demineralized water.
l
--a
The statement that no equipment or system failures had been experienced j
at BSEP conflicted directly with LER 82-005/01T which was submitted in l
January 1982.
In this report, a total loss of RHR shutdown cooling and suppression pool cooling was experienced when the RHRSW pumps would not respond to a start signal.
This refusal to start was attributed to the loss of essential suction header pressure switches which produce pump start lockout signals.
The pressure switch failures were believed to have-been taused by sensor-line sedimentation plugging.
During the meeting, however, BSEP personnel noted that subsequent to the issuance of the information upon which the LER was based., further study revealed that this was not the case.
When the sensing lines were flushed, sediment was released but its consistency and quantity were not sufficient to cause problems. The actual causes were an open power supply circuit breaker to one pressure switch and a lack of operating fluid in the diaphragm housing of the other pressure switch.
A revised LER is being prepared to reflect these findings.
When queried on whether the sediment quality, and thereby the resultant problem potential, was seasonal or weather-condition dependent, BSEP personnel responded that their experience has been that while the quantity of sediment rsaching tha service water pumps is dependent on
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seasonal and weather conditions, the quality does not seem to vary. To date, this variance has not caused any n'oticeable problems.
As an example they noted that no problems had occurred after heavy sediment pr6ducing seasonal rains caused by the passing of a tropical storm.
In summary, BSEP personnel believe that the programs and actions which they have implemented, along with the sediment quality mitigate the concern of small line fouling due to' sedimentation.
2.5 Further Actions Combining the information gathered during the site vis'it with.other research material will lead to engineering evaluations of the recently reported events at BSEP involving equipment environmental qualification problems and RHR loss due to RHRSW difficulties.
Included in the RHR report will be the results of a follow-up telecon of April 9,1982.
Medhat El-Zeftawy Office for Analysis and Evaluation of Operational Data 44 I Thomas Wolf Office for Analysis and Evaluation of Operational Data O
o PARTICIPANTS
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Name Title
_... _. Organization _
NRC(AE00)
S. Rubin Lead Engineer, Reactor Systems 4, Reactor Operations Analysis Branch NRC(AE0D)
M. El-Zeftawy Reactor Systems Engineer, Reactor Systems 4, Reactor Operations Branch NRC(AE0D)
T. Wolf Reactor Systems Engineer, Reactor.
Systems 4, Reactor Operations Branch NRC (Region)
L. Garner BSEP Resident Inspector CP&L (HDQTS)
J. McQueen, Jr.
Project Enginer, BSEP Licensing CP&L (HDQTS)
M. Grim Engineer, BSEP Licensing CP&L(BSEP)
T. Brown Senior Specialist, Electrical CP&L(BSEP)
B. Creech I&C, Electrical,
D. Novotny Senior Specialist, Licensing CP&L(BSEP)
B. Parks
L. Hewlett Senior Engineer, 'BSEP CP&L(BSEP)
B. He'ssitt*
Lea'd Engineer, BESU/NPED CP&L(BSEP)
R. Poulk, Jr.
Specialist, Regulatory Compliance CP&L(BSEP)
K. Enzor Supervisor, I&C Electrical CP&L(BSEP)
G. Thompson Project Engineer, B0P/ Electrical CP&L(BSEP)
W. Tucker Manager, Technical Support
- Part time Figure 1 Brunswick Steam Electric Plant Site Visit / Meeting Participants 9
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(1)
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Brunswick Steam Electric Plant 1
Figure 2:
Representative Moisture Intrusion Pathways
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Envitensental ove11ffeerten
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In general, F.aintenance actions should be performed to such an acceptance criteria that the car, ability of the equipcent vill est be degraded f rom the plant construction specifications. D e proper rateriale to ensure this criteria are procured and controlled under Stores a=d Quality Assurance procedures. ne proper maintenasce practices to ensure attain =ent of this criteria are guided by caintenance procedures, maintenance instructions, aaJ ;cr a.ent trainin;. ne sb.eral critera s is ;i.Nr. in the evirst. ents!
qualgfiratica rulcs given in this section sad further s;ecific critaris ay
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be provided in other Maints.a.neg,docume.nts auch as Maintesance Instructions and Vork Authorisation.
A.
All Maintenance actions must stintain the specification for enviret= ental qualification on Class 1E equipeent as cor=itted to in App'endia M to the{!!AR. As an example, the conditions that sust be set inside the pri=ary containc.ent ares 1.
[ressure - each co=ponent must be maintained such that it will f unction properly under normal and accident a=hient pressures ranging fres -2 to 56 psis.
2.
Temperature - each ce=ponent must be maintained such that it vill function properly under normal and accident te:peratures as high as 3&O*T.
3.
Humidity - each component must be maintained such that it vill function properly under normal and accident hc=idity as high as 100 percent.
4 Integrated Radiatio'n Lose 1evela - frequently repair materials must be certified for high radistion envirenzent,.
5.
Spray - each component, must be u.aintained such that it vill functioh preperly under mor=al and accident conditions of 200*T spray.
Detailed conditions that must be met in other plant buildings / areas are provided in Tigure X.7.9-1 of the TSAR.
'3.
To preserve the environnental qualificatiens discussed above, some general maintenance practices that must be adhered to are
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1.
De proper 'Q" list consumables listed in plant operating Manual, vol. XI, sk. 2, supplement 1 the
- Q" list cust be used. This list is duplicated in Paragraph C.
e 2.
All gaskets and seating surf aces including protective covers must be 1.spected prior to reasse=hly. Any deficiency test be corrected or documented.
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3.
All fasteners must be installed. n e envirenzental guslity of each component is violated if any fastener is =1ssing.
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Instrumentation. Water and Moisture Intrusion Sample Work Request and Authorization Form
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