IR 05000269/1986009

Insp Repts 50-269/86-09,50-270/86-09 & 50-287/86-09 on 860306.No Violation or Deviation Noted.Major Areas Inspected:Steam Generator Cleaning & Maint Re Secondary Water Cycle

ML20210H849
Person / Time
Site:	Oconee
Issue date:	03/20/1986
From:	Ross W, Stoddart P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20210H847	List: IR 05000269/1986009 ML20210H844
References
50-269-86-09, 50-269-86-9, 50-270-86-09, 50-270-86-9, 50-287-86-09, 50-287-86-9, NUDOCS 8604030203
Download: ML20210H849 (5)

Text

c- a UNITED STATES m af roq'o NUCLEAR REGULA~ORY COMMISSION

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REGION 11 g ,j 101 MARIETTA STREET, *' 's ATLANT A. GEORGI A J0323

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/ MAR 21 1986 Report Nos.: 50-269/86-09, 50-270/86-09, and 50-287/86-09 Licensee: Duke Power Company 422 South Church Street Charlotte, NC 28242 Docket Nos.: 50-269, 50-270, and 50-287 License Nos.: DPR-38, DPR-47, and DPR-55 Facility Name: Oconee 1, 2, and 3 Inspection Conduct d: t Ma h 6, 1986 Inspector: l U M / 6 Date Signed W. J. Rosg ' ~

• S/s0lYS Approved by: h Mff P. G." Stoddart n $ ', Acting Section Chief Date

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Signed Division of Radiation Safety and Safeguards SUMMARY Scope: This special announced inspection entailed eight inspector-hours onsite in the areas of steam generator cleaning and maintenance related to the secondary water cycl Results: No violations or deviations were identifie '3 860321 PDR ADOCK 05000269 G PDR

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REPORT DETAILS Persons Contacted Licensee Employees T. S. Barr, Superintendent of Technical Services

• E. L. Jackson, Project Engineer B. K. Jones, Project Shift Manager D. P. Rochester, Project Chemical Engineer Other Organizations S. J. Weems, MPR Associates, In D. L. Tate, Babcock and Wilcox NRC Resident Inspectors J. Bryant, Senior Resident Inspector K. Sasser, Resident Inspector

• Attended exit interview Exit Interview The inspection scope and findings were summarized on March 6,1986, with those persons indicated in Paragraph 1 abov . Licensee Action on Previous Enforcement Matters This subject was not addressed in the inspectio . Unresolved Items Unresolved items were not identified during the inspectio . Monitoring of Licensee Maintenance Activities Related to the Secondary Water System (79701)

The primary purpose of this special inspection was to monitor activities related to cleaning of the once-through steam generators (OTSG) in Unit 1 and to review the results of similar cleaning of the OTSGs in Units 2 and 3 (see Inspection Report Nos. 50-269/270/287/85-16 dated July 8, 1985). A secondary purpose was to monitor other maintenance activities related to the inspection and modification of components in the secondary water cycl At the time of this inspection Unit I was in its Cycle 9 refueling outage while Units 2 and 3 were operating.

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1 Steam Generator Cleaning As the result of sludge (solid oxides of ircn) buildup in the tube I bundle and on the lower tube sheet of the trio OT3Gs of each of the three Oconee t. nits, the flow of the feedwater/ steam mixture through the tube bundles wes retarded to the extent that the maximum achievable power levels of the three units were jeopardize In 1985, the licensee used a cobbinction of cleaning and sludge removal processes on

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Units 2 and 3 to improve the flow of water through the steam generator tube bundles. At that time, both of these processes were still ir. the development stage, and t.1e results of the cleaning and the sludge removal steps did not meet the 11cansee's expectations. However, both '

Units 2 and 3 were able to achieve and maintain maximum design power levels following the stea: generatirs cleaning. Although the maximum power level of Unit I was not yet degraded by increased pressure differential through the OTSGs, the licensee chose to perform a similar cleaning operation of the two OTSGs in Unit I d. ring the 1986 refueling outag '

(1) Slap-Cleaning Process Eiased on experierice with Oconee Units 2 and 3, as wel! as at two other nuclear plants designed by Babcock and Wilcox, the reduced ;

flow through the OTSG tube bundles was attributed to blockage of !

the broached tube-holes in the lower tube support sheet The reduction of flow through these holes was thougnt to result from the deposition of iron oxide through several mechanisms; e.g.,

gradual buildup of oxide on the sides of the tubes and the tul/-

support plates through deposition from the water / steam mixture as it rises and is further heated to supersaturased steam, or by '

transfer of crystalline or amorphous oxide re.idues from other parts of the tube and tube s*:pport plate The licensee, in association with other utilities and MPR Associates, Inc. was developing a " water-slap" process *or removing solid material from the broached holes and from oitar surfaces within the tube bundle and transferring this sludge te the lower tube ' sheet where it could be removed from the ste;m generator. A brief description of this proprietary process and a review of the safety analyses performed by MPR Associat,es, as well as by Babcock and Milcox, were incladed in Inspection Reports Nos. 50-269/270/287/85-1 The inspector was informed that the " slap-cleaning" procedure had been further refined to achieve higher levels of energy in the

" slap" process while, at the same time, the stress levels placed on components of the steam generator had been decreased. The modified procedure was tested in cooperation with Babcock and Wilcox, on an OTSG mockup in January 1986, and the results were found to be consistent with the safety evaluation. The inspector briefly reviewed the proprietary safety evaluation of the modified

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r procedure in an effort to comprehend the bases of the improvement Re insnetor did not identify .Iny unreviewed saf ety issue The inspector established that the licensee had developed a j written procedure (TT/UA/425/02) Or nerforming the " water-slap" cleaning process. The procedere was b61ng followed in the same

- manner as discussed fn Inspection Report 85-16 with the activities

! within the containment building being directed and monitorc) from 3 e control stasion outside of the containment buildin The cleaning procedure was b6's.g coordinated with the sludge lancing efforts described as follows: the sludge that was observed on the j tube sheet after Unit 1 shutdown' was removed to the extent possible by sludge lancing; the st ?am generator was then cleaned by the " water slap" process; and then the tube sheet was sludge lanced again. During the period the inspector was on site, Steam

. Generator "B" was sludge lanced once and was being cleaned, while

Steam Generator "A" was being sludge lanced for the second tim The Nater-slap" process was performed in the same manner as during the mockup tests. The written procedure was followed and it was the inspector's perception that no significant problems

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(2) Sludge Lancing

l Previous efforts to remove sludge from OTSGs by lancing procedures

were not en:ouragin However, Babcock and Wilcox recently

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developed improved lances for flushing solids from the tube lanes to the annulus region where the solids could be removed by suction. The imoroved lances were evaluated with the same mockup "

OTSG used for the " water-slap" process and were used to reduce the mass of solids in OTSG "A" and "B" to the greatest extent possible before the " water-slap" process was initiated. Approximately 175

pounds of iron oxide sludge was removed from each OTSG; however, ,

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j the design of the annulus region reduced the mobility of the

! " bundle" lance that was used in conjunction with a " lane" lance.

J Consequently, approximately 50% of the sludge remained on the i lower tube sheet at the conclusion of the lancing. It was hoped

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that a more complete removal of sludge would be achieved during

the second phase of lancing (after the cleaning process was

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complete).

j In order to improve the capability to inspect the interior of the t

tube bundle and to monitor the effectiveness of both the cleaning i and lancing processes, an additional 4-3/4" hand hold was drilled in each OTSG between the fifth and sixth tube support plates.

i The inspector will assess the success of the lancing process at a

! later date af ter the second-stage lancing has been completed. It was the licensee's position that the degree to which the holes in the tube support plates were clogged was not related to the mass

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of sludge on the lower tube sheet; however, the in-flow of feedwater would be affected if a large mass of sludge covered the lower tube shee .c. Inspection of Low-Pressure Turbines While Unit I was shutdown, the licensee inspected the blades of the wheels on the low pressure turbines. The inspector was informed that crack indications were observed by ultrasonic tests in some of the pins that connect the blades to the wheels. At the time of the inspection, these cracks had not been completely analyzed and evaluated; therefore, it was not known if there was any correlation to the licensee's control of secondary water chemistr This matter was designated Inspector Followup Item 86-09-0 d. Water Cleanup System The inspector was informed that components of a new design were being installed in the filter /demineralizer units of the water cleanup system. This action was being taken in an effort to eliminate " throw" or " leakage" of fragments of ion-exchange resin beads into the feedwater.

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