IR 05000369/1987023
| ML20237J347 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 08/07/1987 |
| From: | Kahle J, Ross W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML20237J337 | List: |
| References | |
| 50-369-87-23, 50-370-87-23, GL-85-02, GL-85-2, IEB-87-001, IEB-87-1, IEIN-86-106, NUDOCS 8708180109 | |
| Download: ML20237J347 (6) | |
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. pa Mooq UNITED SVATES
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REGION 11
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j 101 MARIETTA STREET, N.W.
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ATLANTA, GEOHGI A 30023 AUG 11 1987
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Report Nos.:
50-369/87-23 and 50-370/87-23 Licensee: Duke Power Company 422 South Church Street Charlotte, NC 28242 Docket Nos.
50-369 and 50-370 License Nos.:
NPF-9 and NPF-7 Facility Name: McGuire Nuclear Station Inspection Condu t d:
uly 20-21, 1987 Inspector:
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W.'J.Rys'
Date Signed Accompanying Personnel:
C. A. Hugbey Approved by:
M6]d 7/77 J.17.' @hle, Section Chief
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Da@ Sisned/
Divis)6n of Radiation Safety and Safeguards i
SUMMARY
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Scope: This routine unannounced inspection was conducted in the area of plant chemistry.
Results:
No violations or deviations were identif,'ed.
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8708100109 870811 PDR ADOCK 05000369 G
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l REPORT DETAILS 1.
Persons Contacted Licensee Employees
- T. L. McConnell, Station Manager M. Funderburg, Station Chemist
- M. Bridges, Power Chemistry Coordinator T. Bumgarner - ISI Engineer T. Cook, Mechanical Maintenance Engineer D. Mays, Project Engineer, General Office F. Wally, Maintenance Engineer NRC Resident Inspector
- S. Guenther
- Attended exit interview 2.
Exit Interview The inspection scope and findings were summarized on July 21, 1987, with those persons indicated in paragraph above.
The inspector described the areas inspected and discussed the inspection findings.
No dissenting comments were received from the licensee.
The licensee did not identify as proprietary any of the material provided to or reviewed by the inspector during this inspection.
3.
Licensee Action on Previous Enforcement Matters
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This subject was not addressed in the inspection.
4.
Unresolved Items Unresolved items were not identified during the inspection.
5.
Plant Chemistry (79701)
l This inspection was performed for the following purposes:
to assess how the licensee had protected the integrity of the steam generators (i.e.,
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the primary coolant pressure boundary) since the last inspection in April 1986 and to review actions being taken by the licensee in response to IE Notice 86-106 and IE Bulletin 87-01 in reference to erosion / corrosion of carbon steel pipe.
At the time of this inspection McGuire Unit I was in the eleventh month of a twelve month fuel cycle (number 4) that had been marked by record run times and decreased number of outages.
Unit 2 had just begun its fourth fuel cycle after a refueling outage.
An audit of operational data revealed that Unit 2 also had operated in a very stable manner (one brief shutdown) during the period since the last inspection in this area.
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l A.
Integrity of Steam Generators By means of audits of chemistry data and discussions with chemistry supervisory personnel the inspectors reassessed the-conditions of the steam generators in both units.
(1) Unit 1 - During the third refueling outage.for this unit, in the summer of 1986, a total.of 37 steam generator tubes had been plugged as the result of ' eddy current tests performed in compliance with Technical Specifications (2 tubes in "C" steam generator, 35 tubes in
"D" steam generator, and no tubes in the
"A" and
"B" steam generators).
The total number of tubes plugged during the operational life of this. unit was 515;'i.
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126, 118, 120 and 151 in steam generators A, B, C, and D.
.These numbers include all of the Row 1 tubes that had been plugged as a preventative measure against failure in the "U" bend region.
During the 1986 outage the licensee also shot peened the tubes in all four steam generators in an effort to prevent further cracking of tubes from the ID side within the tube sheet. region.
This primary-side cracking mechanism had been attributed to stresses induced when the tubes were rolled into the holes in the tube sheets during manufacturing and had begun to initiate cracks after a relatively long " incubation period."
The inspectors established that the Technical Specifications for both McGuire Units had been revised to apply special testing and reporting conditions to tubes "with degradations -(caused by primary side cracking) equal to or greater than 40% below the F*
distance and not degraded (1.
e., no indications of cracking) in the F* distance."
The F* distance is defined as "the distance into the tubesheet from the top face of the tubesheet or the top of the last hardroll, whichever is lower (further into the tubesheet), that has been conservatively chosen to be 2 inches".
The inspectors were informed that 100% of the un-plugged tubes would be eddy current tested during the upcoming refueling outage beginning in September 1987.
The steam generators will also be sludge lanced to remove solids from the tubesheets of each steam genesator.
(2) Unit 2 - The principal type of degradation of steam generator tubes that had been observed.in this unit during the last year was also attributed to primary side stress cracking.
During the recent refueling outage additional tubes (35, 42, 30, and 34 in Steam Generators A, B, C, and D) had to be plugged as the result of eddy current tests.
Consequently, approximately 150 tubes, including the Row I tubes, had been plugged in each steam generator.
The inspectors were informed that a total of approximately 400 pounds of iron oxide sludge was removed from I
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the four steam generators in this unit during the recent refueling outage.
(3) Chemistry Control - The absence of other types of chemical induced corrosion within the steam generators was attributed by the licensee to prevention of ingress of corrosive species, especially through condenser leaks and the water treatment plant.
During the past year only one condenser leak had been
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encountered.
This leak was thought to have been caused by a loose object that had fallen into the condenser of Unit I during the installation of new low-pressure turbine rotors in the summer of 1986.
The water treatment plant had provided makeup
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water of quality sufficient to meet the criteria of the Steam Generator Owners Group (SG0G).
However, inbalances between cation conductivity and anion concentrations in the steam generator blowdown indicated that non-ionic (organic) impurities were not being removed by the purification train of the water treatment plant.
The effect was greater in Unit 2 than in Unit 1 (approximately the equivalent of 0.17 umho vs. 0.05 umho).
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Otherwise, the cation conductivity of water in the steam
generators of both units would have been of very high purity (i.e. 2 0.01-0.15 umho/cm) because the concentrations of individual, potentially corrosive anions, such as chloride, fluoride, and sulfate, remained below the lower detectable I
limits of 2 1 ppb. The inspectors were informed that plans were i
being made to bring in a mobile reverse-osmosis water i
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purification system to determine if greater retention of the suspected organic compounds could be achieved.
The inspectors were informed of one transient in the chemistry control of Unit 1 caused by the leakage of closed cycle plant heating water into the secondary cooling cycle via the condensate storage tank.
This heating water contained sodium nitrite as a corrosion inhibitor and, therefore, caused an increase in cation conductivity; however sodium nitrite was not considered to act as a corrodant within the secondary water system.
The licensee had completed the modifications of the condensate polishers discussed in the last inspection report in this area.
The inspectors were informed that the new, sintered metal filter tubes had essentially stopped leakage of ion exchange resin into the feedwater and steam generators, thereby reducing the concentration of sulfate ions caused by thermal degradation of this resin.
However, difficulties were being encountered in achieving uniform pre-coats on the new tubes, and tne tubes were being returned periodically to the vendor for special cleaning.
The condensate cleanup system was continuing to be used for startup cleanup; however, all but one filter / demineralized vessel was bypassed when the unit was at full power because of diminished capacity of the condensate booster pumps.
When the
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unit was ' operating at full power this single polisher vessel was
used to effect cleanup of the steam generator blowdown.
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(approximately 20% dilution) partial flow of condensate was i
maintained to ' cool the blowdown water below the threshold l
temperature for resin degradation '(i.e.,
to keep the temperature below a-140 F).
(4) Assessment - The inspectors concluded that through efficient operation of the major components of the secondary water system and effective chemistry control the licensee. continued to attain, and significantly exceed, the chemistry control criteria recommended by the SG0G.
The principal, if not the only, cause of degradation of steam generator tubes has been attributed to primary side stress induced cracking that was not directly related to chemistry control.
The inspectors considered the licensee to be taking appropriate actions, based on current technology, to minimize /stop further stress corrosion.
B.
Pipe Thinning As a followup of the Notice 86-106 (and Supplements) and Bulletin 87-01 published by the NRC in relation to the feedwater pipe rupture at'the Surry Nuclear Station in December 1986, the inspectors reviewed the licensee's actions being taken in response.
The inspectors were informed that.a surveillance program already was being implemented related to specific carbon steel components (e.g., feedwater heater bleed systems) where the potential for erosion / corrosion was considered to be relatively high.
The heater bleed systems in Unit I had been inspected during three refueling outages (1982,1983, and 1986).
Subsequent to the issuance of IE Notice 86-106 the licensee also had inspected six pipe fittings in feedwater. lines, sixteen fittings in the condensate lines, as well as 35 other pipes and
' fittings associated with the turbine and moisture ' separator.
The inspectors were informed-that these inspections revealed-loss of metal in some areas.
Faulty pipe and elbows will be replaced with stainless steel at a later, unspecified, date.
A Pipe Erosion Control Group had been formed-to follow this subject, and a new manual PT/0/B/4700/53, " Pipe Erosion Control Program Manual," had been developed as guidelines for craft personnel performing ultrasonic measurements at specified inspection points and grids.
These points were established by the Design Engineering Department based on the temperature and velocity of water in the systems, two parameters considered to be associated with erosion / corrosion.
The licensee had only recently received IE Bulletin 87-01 and had not collected the plant specific data required in response to this Bulletin.
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The inspectors considered that the licensee was taking appropriate action in response to IE Notice 86-106 and relative to protection of carbon steel pipe against erosion / corrosion.
C.
Water Chemistry Control Program (79701)
The inspectors noted that since the last inspection in this area personnel changes had been made throughout the Chemistry supervisory staff.
Since all of the new supervisors had acceptable levels of experience in the licensee's chemistry program the inspectors did not observe any significant decrease in capability.
The inspectors were informed that a new Station Training Group had been formed to assist in the on-the-job training of chemistry technicians.
After discussing the objectives of this new program with the Chemistry Training Coordinator, the inspectors agreed that this action could enhar.ce the overall training program and was a positive action in upgrading the qualifications of the Chemistry staff.
The inspectors also reviewed the quality control program of the Chemistry Group and found that the elements of the program continued to be satisfactory.
The inspectors were briefed on proposed modifications to the secondary chemistry laboratory that had been designed to upgrade the chemistry staff's capability to monitor key control parameters with inline, continuous readout analytical instrumentation.
During this part of the inspection no violations or deviations were identified.
6.
Inspector Followup Items (Closed) Inspector Followup Item 50-369, 270/86-10-01; Response to Generic Letter 85-02.
The inspector made a summary review of the major elements of the licensee's water chemistry control program.
During this inspection the inspector established that in its response to NRC Generic Letter 85-02 the licensee stated that the SG0G guidelines related to PWR Secondary Water Chemistry had been adopted in principle and philosophy.
This item is closed.
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