ML20235E911

Insp Rept 50-029/87-07 on 870511-29.Violations Noted.Major Areas Inspected:Steam Generator Tube Eddy Current Surveillance Test Sampling,Eddy Current Data Analyses, Secondary Water Chemistry Controls & Visual Insps

ML20235E911
Person / Time
Site:	Yankee Rowe
Issue date:	09/03/1987
From:	Gray E, Lodewyk A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20235E901	List: ML20235E898 ML20235E904 ML20235E911
References
50-029-87-07, 50-29-87-7, NUDOCS 8709280318
Download: ML20235E911 (10)

See also: IR 05000029/1987007

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Report No. 50-29/87-07

Docket No. 50-29

License No. DPR-3

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Licensee: Yankee Atomic Electric Company j

1671 Worcester Road

Framingham, Massachusetts 01701

Facility Name:- Yankee Nuclear Power Station

Inspection At: Rowe, Massachusetts .

Inspection Conducted: May 11-29, 1987

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Inspector: 4 s' .7!./ 8 7

date

A. J. Lodewyk, g ctor Engineer

Approved by: ") __

F. H. Gray, Acting 4hief, Materials and

fd/87

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Processes Section

Inspection Summary: A routine, unannounced inspection was conducted by one

region-based inspector of activities associsted with the licensee's Inservice

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Inspection Program and Steam Generator integrity. Those areas examined onsite l

included: steam generator tube eddy current surveillance test sampling; eddy l

current data analyses; secondary water chemistry controls and visual inspec-

i tions; and, associated radiation protection measures and housekeeping. An

l in-office review was also conducted relating to results of the steam generator  ;

inspections and Licensee Event Report No. 50-29/87-06.

Results: During this inspection, one violation was identified relating to

failure to plug defective steam generatar tubes. Additional areas of concern

discussed include technical specification sampling criteria, steam generator

test equipment usage, and observed housekeeping practices.

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DETAILS

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1.0 Persons Contacted

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Throughout this inspection, various' site and engineering office repre- 1

sentatives were interviewed for information and auditing purposes. l

Those persons contacted include the following:

Yankee Atomic Electric Company (YAEC)

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• B. L. Drawbridge, Assistant Plant Superintendent

N. W. Featherston, Inservice Inspection Coordinator

C. Garrow, Reactor Engineer - Framingham

• T. K. Henderson, Technical Director

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J. Lance, Engineering Branch - Framingham

S. M. Litchfield, Medical and Plant Safety Supervisor i

D. F. May, Reactor Engineer (Eddy Current Test Coordinator)  ;

• R. A. Mellor, Assistant Technical Director and Chemistry Manager i

• N. N. St. Laurent, Plant Superintendent

• R..N. Williams, Reactor Engineering Manager

U.S. Nuclear Regulatory Commission (NRC) 'l

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• H. Eichenholz, Senior Resident Inspector

• Denotes those persons present at the exit meeting conducted at the closa

of this inspection.

2.0 Steam Generator Preventive Maintenance

The licensee's steam generator (S/G) preventive maintenance program

(as it is related to maintaining S/G integrity and controlling station

secondary water chemistry) was reviewed relative to criteria, commitments,

and recommendations provided in:

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Condition 2.C(5) of License No. DPR-3 regarding a secondary water

chemistry monitoring program

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Facility Technical Specifications Section 3/4.10, " Steam Generators"

limiting conditions for operation and surveillance requirements

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YAEC August 12, 1985 response to Generic Letter 85-02

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Electric Power Research Institute (EPRI) Report NP-2704-SR, "PWR

Secondary Water Chemistry Guidelines," Revision 1 (1984)

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NUREG-0844, "NRC Integrated Program for the Resolution of Unresolved

Safety Issues A-3, A-4, and A-5 Regarding Steam Generator-Tube

Integrity"

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Licensee performance in S/G preventive maintenance was determined '

by interviews with chemistry, radiation protection, maintenance, 1

engineering and contractor personnel; review of selected procedures, i

reports and records; and observations of plant facilities and equipment i

during facility tours. The review addressed the licensee's maintenance, ,

Inservice Inspection (ISI) and water chemistry program procedures, ]

policies and implementation.

i 2.1 Steam Generator Tube Inspection Sample

YAEC technical specifications require the steam generator tube

sample to consist of at least 3% of.the total number of steam

generator tubes, including a representative sample from areas pre-

viously experiencing degradation and randomly selected tubes. The

intent of the technical specification sampling requirements is

twofold: to identify defective tubes in previously known areas of

degradation; and, to detect any new, service induced modes of

degradation.

Previous inspection of the number 2 steam generator was conducted in  !

1984 from the cold leg side. At that time, effective ECT was not  !

completed within the areas of steam generator tubes with primary side l

magnetite deposits. ' Magnetite deposits are located in the lower

steam generator area, from the tube sheet up to approximately 50-60

inches above the tube sheet.

During the current 1987, Cycle 18/19 refueling outage, the licensee

completed eddy current testing (ECT) from the hot leg side of the

number 2 steam generator. The lic2nsee completed a 100% inspection

of the accessible hot leg side tubes. The licensee considered inac-

cessible tubes to be (a) permanently plugged tubes, (b) tubes with

temporary template or equipment plugs, and (c) tubes outside the i

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reach of the SM-4 probe manipulator. Also, the inner tube, small

U-bend radius does not always permit passage of an eddy current p' robe

from the Hot Leg to the Cold Leg for inspection. The tube inspection i

sample included previously identified areas of tube degradation such j

as (a) pitt-like eddy current signals in the lower, kidney-shaped i

region, and (b) degradation at the U-bend tube support bars. The

inspection sample also included full length tube inspections intended ,

to identify any new modes of degradation that may have developed '

since previous surveillance inspections.

Prior to the outage, the ECT contractors (Zetec) developed a testing

technique to rotate and phase-out magnetite / copper signals previously i

experienced in S/G tubes with primary side corrosion deposits. ECT J

was performed using test frequencies of 600, 140, 45 and 10 KHz. The  ;

steam generator tubing is 0.75" 0.D. x 0.072" wall thickness and is I

constructed of 304 Stainless Steel. Onsite, the inspector observed

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ECT data acquisition, verified field test frequencies, and confirmed

proper probe speeds. Results of the 1987 tube inspections are shown

in Table I. No significant changes in rate of tube degradation and i

no new modes of degradation were identified by the licensee.

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TABLE I

STEAM GENERATOR NO. 2 1987

INSPECTION RESULTS

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Hot Leg Cold Leg U-bend Supports

No. of tubes 1507 1193 1507

inspected

No. of. defective 7 12 2

tubes identified

No. of degraded 8 17 7

tubes identified

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For determining Technical Specification resampling characteristics,

the licensee elected to re-analyze 1984 ECT data to' determine which

indications had grown less than 10%. Re-analysis of this data de-

termined eight of the twenty-one defective indications should have

been identified and plugged previously. (This concern is addressed

in section 2.2 of this report.) The remaining 13 defective tubes

placed the inspection results 1n Technical Specification category-

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C-2, as more than 1 but less than 1% of the 1507 tubes inspected were

found to be defective. Therefore, it was not necessary by technical

specifications to expand the inspection to other steam generators.

Based upon the above information, the licensee's steam generator tube

sampling for the 1987 outage meets the intent and criteria of the

current YNPS Technical Specifications. However, following several

telephone conferences, cognizant YAEC, Regional and NRR staff agree

that the current Technical Specifications require' updating regarding

steam generator surveillance practices. Licensee and NRC personnel

agreed that improvements can be made in the S/G technical specifica-

tions in areas such as inspection sample sizes and acceptance

criteria and definition of " full length" tube inspection. Changes to

the station technical specifications are to be tracked, discussed,

reviewed and approved by NRC personnel through the facility licensing

process. The inspector had no further questions regarding this

matter at this time.

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2.2 Eddy Current Data Analyses-

As discussed in section 2.1 of this report, the licensee. initiated a

re-analyses of 1984 eddy current test data during the 1987 refueling

outage to establish Technical: Specification resampling requirements.

During.this review, inadequacies in previous data analyses were

discovered and the licensee proceeded to re-analyze all.of the

latest eddy current data for each steam generator. The re-analyses

were performed using the DDA-4' analysis system and identified a

number of previously unidentified, unacceptable eddy current

indications. The results of all the 1987 secondary, reanalyses

identified the following defective tubes subsequent to a primary

analyses:

Year of- Additional No.

Primary of defective tubes

Analyses Identified in 1987 Reanalysis

steam generator no. I 1985 0

steam generator no. 2 1987 5

1984 9*

steam generator no. 3 1984 11

steam generator no. 4 1984 12

Total number of defective tubes identified

during this outages secondary reanalyses = 37

• one defective tube was not identified during 1987 analyses as it

is a cold leg indication for which 1987 data was not obtained.

The remaining 8 defective tubes were identified again during

1987 testing and are included in the results discussed in

section 2.1 of this report.

In one instance, a defective (ECT indication >40% through-wall)

indication had been noted on the 1984 data strip chart. However,

the defect had not been properly recorded and subsequently the

defective tube was not repaired. Consequently, the tube remained

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unplugged and the steam generators were placed in service for two

full operating cycles. This event violates YNPS Technical Specifi-

l cation Section 4.4.10.4(b), acceptance criteria, which states the

i facility steam generators are to be determined operable after plug-

I ging all tubes exceeding the plugging limit (87-07-01). Also, this

l event represents a lack of adequate' Quality Control during completion

of ECT and data analyses.

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Prudent corrective actions taken by the licensee to assure the t

integrity of the steam generator tubes include the 1987 re-analyses

of the most recent ECT data for the hot and cold legs of all four

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steam generators. The additional defective tubes which were identi-

fied during the 1987 re-analyses, were plugged during the current  ;

cycle 18/19 refueling outage. No tube leakage was' experienced during j

the. previous operating cycles, thus indicating the integrity of the

primary reactor coolant pressure boundary had been maintained and

there was no adverse impact on the health and safety of the public.

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Details of'this event are' discussed in Licensee Event Report -

50-29/87-06. The licensee has initiated an investigation. for generic I

implications of these events and to determine if additional reporting

requirements are necessary under 10 CFR 21.

, NRC Headquarters, regional and resident personnel will review future j

implementation of corrective actions to prevent recurrence of this .j

event.

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2.3 Radiation Exposure 1

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An inspection of the onsite training facilities and field eddy

current testing was performed to assess the. licensee's measures to L

maintain personnel radiation exposures as-low-as-reasonably- j

achievable during steam generator surveillance inspections. Training j

of steam generator contract workers included review of onsite radia-  !

tion protection policies and practical steam generator mockup j

testing. YAES utilizes a wooden simulation of the lower steam ge- )

nerator region for practical training. The mockup primarily consists j

of a partial steam generator frame and a number of tube sheet holes.

Industry standard mockup models consist of a complete metal lower

steam generator and tube sheet. Mockup training and testing is

intended to familiarize personnel with work activities such as equip-

ment installation procedures prior to entering high radiation areas.

During this outage, three separate personnel entries were required to

complete installation of the No. 2 steam generator eddy current test

equipment. The large number of steam generator entries could be  ;

attributed to the facilities less than standard mockup. Through j

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discussions with counterparts and management relating to this sub- .l

Ject, the licensee indicated updated eddy current test equipment

would be evaluated for site-specific applicability and use during

future steam generator inspections. Upgrades in ECT equipment would

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not require entry into the steam generator lower plenum for equipment

l installation, thus reducing personnel time within this high radiation

area.

Other ECT high radiation exposures are associated with those work

activities performed on the work platform situated directly outside

the steam generator manway. Although it is not yet a common

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industry practice, the use of a temporary lead shield door on manways

has proven effective in reducing platform radiation fields at other

nuclear power plants.

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The above practices were discussed with licensee representatives who

indicated a strong desire to keep personnel exposures low consistent

with ALARA principles. Feasibility regarding implementation of these

techniques would be subject to YAEC engineering and management

review.

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Inspector observation of steam generator platform work activities

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included maintenance and cleaning of the ECT probe and probe pusher

by contractor technicians. Frequent cleaning of the ECT equipment

was necessary as loose primary-side magnetite deposits _were being

dislodged by the probes centering fingers. The dislodged magnetite

interfered with test probe manipulation and testing, requiring

technicians to remove the magnetite deposits which had accumulated on

test equipment. During routine surveillance testing, the inspector

observed ECT technicians shaking the loose magnetite from the test

probe onto the work platform. At the inspector's request, the Radia-  ;

tion protection Supervisor immediately obtained a survey of the work

platform floor. The loose magnetite deposits were found to contain

high beta and low gamma radiation. It was determined that the work

platform area background radiation level had not changed signifi-

cantly and that additional radiation cetectors (foot dosimetry) were i

not necessary for the ECT technicians. However, as the loose magne- 1

tite did create a potential airborne radiation source the technicians j

were instructed to contain the removed magnetite flakes as much as i

possible inside work buckets. Further discussions with licensee j

representatives determined the previous shift of.ECT technicians had i

been instructed to contain the loose magnetite upon removal and the l

instructions had not.been transfered as workers changed. The  ;

licensee's radiation personnel took immediate action in addressing j

and correcting the above concern. '

The total radiation exposure obtained during steam generator inspec-

tion and maintenance activities was not available at this time. The

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expended man-rem will be subject to further NRC review upon comple-

tion of the steam generator work activities and subsequent reporting '

to the NRC, as required. '

2.4 Secondary System Water Chemistry Controls

License No. DPR-3, Section 2.C(5) requires YNPS to maintain a

secondary water chemistry monitoring program to inhibit steam

generator tube degradation. Secondary system water chemistry

requirements have been subject to review in an attempt to improve

the environmental conditions associated with steam generators.

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Procedure AP-9002, secondary water chemistry, was found to be

consistent with EPRI established guidelines. Review of chemical

data records for the past operating cycle determined chemical con-

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centrations were maintained within the administrative requirements.

In'particular, ammonia and dissolved oxygen concentrations have been

limited to minimize corresion of copper-bearing materials in the

secondary system. In addition to chemical parameter limits, licensee

l efforts to maintain good water chemistry include: replacement of the I

l copper bearing Air-Ejector portion of the condensate system with 304 )

! stainless steel; and, sample ECT of condenser tubes based upon l

previously experienced leaks. '

Overall, review of the licensee's secondary water chemistry program

has determined the licensee's activities meet the general license

requirement.

2.5 Secondary Side Steam Generator Inspections

Steam generator secondary side visual inspections are performed to

assure component weld integrity and to reduce the probability of

introducing loose parts to the steam generator tubes. Loose parts ]

in the plant secondary system may act as missiles or result in wear

of the reactor coolant pressure boundary during normal plant opera-

tion. Previous and present outage activities relating to the preven-

tion and detection of steam generator loose parts are discussed

below:

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During the performance of secondary side inspections of the facility- l

steam . generators in November,1985, the licensee identified weld J

cracks on the No. 2 and 3 Steam Generator feed rings. The cracks  ;

were in the non-ASME Code welds in the "T" to the feed ring joint

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and were circumferentia'l in nature. The 1985 visual inspections'

l also noted that three.of the six original. "Z" feed ring support

i brackets in steam generator no. 3 were missing. The details of the

I corrective actions take_n in response to these-defects are discussed

further in NRC inspection. report.no. 50-29/85-18. Subsequent to the

defect corrective actions, extensive visual inspections were con-

ducted in the No. 2 and 3 steam generators in response to reports of

possible loose parts remaining in the secondary sides from associated

maintenance hetivities. Corrective measures for this concern

included establishing procedure requirements for: housekeeping logs;

zone III personnel and equipment accountability; and, specific steam

generator access and work control.

During the 1987 outage, the inspector addressed the above concerns

by accompanying ISI personnel on the internal no. I and 3 steam

generator secondary side visual inspections. Independent testing

and observations found no evidence of circumferential cracking in

,. feed rings or any other new modes of degradation. Housekeeping logs

I and accountability procedures were strictly adhered to throughout

both steam generator inspections

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Also, extensive radiation protection coverage was provided throughout

the secondary side visual inspection' activities. Based upon these

inspection results, it appears the corrective actions taken to ad-

dress the November, 1985 visual inspection and maintenance house-

keeping concerns were adequate.

3.0 General Housekeeping _g

Throughout this inspection several plant tours were performed, specifical-

ly within the yard areas, the warehouse and the reactor refueling floor.

Areas were surveyed for housekeeping practices which, ove' 11, appeared to

be good, with the following exceptions.

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l. Early in the outage during a tour of the yard between facility buildings,

the inspector observed a number of radiation protection materials strewn

throughout the area. A sample of cotton gloves, rubber gloves, swipes

and booties were taken to the health physics access control point and

checked for contamination. All of the articles surveyed were found to be

radiologically clean. Although none of the samples were potential person-

nel hazards, the radiation protection supervisor and rerident inspector

agreed general housekeeping practices could be improved. The radiation

protection supervisor discussed this concern with appropriate licensee

personnel and subsequently, no further articles implying potential conta-

mination were found in the yard areas during this insper. tion.

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Housekeeping practices on the reactor refueling floor was an area of

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further concern to the inspector. Although a large amount of maintenance

activities and radiation protection coverage was being performed, an

inordinate amount of debris and unused tools were found scattered through-

out the refueling deck floor. Small articles included such items as nuts,

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bolts, electrical extension cords, tape rolls, and storage buckets. These

and other items were considered obstacles affecting inspector and worker

routine movement about the floor. The reactor head had not been lifted at

j the time of this inspection however a potential for inadvertently intro-

i ducing unwanted equipment or personnel into an opened vessel was apparent )

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under these conditions. Licensee senior management initiated immediate

corrective actions to address this concern, including revision of

Procedure No. OP-1100, to ensure all debris has been removed from the area

adjacent to vessel.

4.0 Licensee Action on Previous Inspection Findings

(Closed) IFI (84-07-01). Office of Nuclear Reactor Regulation review of

the licensee's proposed Technical Specifications and justification for

eddy current sample sizes. On May 25, 1984, the licensee provided justi-

fication to the NRC for modification of the YNPS Technical Specifications

relating to steam generator tube examination sample sizes. This item is

closed based upon the licensee's withdrawal of the request for Technical

Specification change. The scope of the steam generator tube inspection

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during this outage was reviewed by NRC Region I and NRR and found accept-  ;

able. The_ scope and results of the steam generator tube eddy current "

examinations during this outage are further discussed in Section 2.1'. The

licensee has indicated that a revised technical ~ specification change ,

request may be submitted in the future. 2

(Closed)IFI(85-18-03}. . The licensee's plans to ' resolve _the' steam

generator No. 2 magnetite formation interference with tube eddy current i

testing. Improvements in eddy current test technology (discussed further I

in section 2.2) resolved the licensee's difficulties in examining portions

of tubes with magnetite deposits. This item is closed.

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5.0 Exit Interview l

The inspector met with licensee representatives (denoted in paragraph 1)

at the conclusion of the onsite inspection on May 15, 1987. The inspector

summarized the purpose, scope and findings of the onsite inspection at

that time. Other items addressed in this report are a result of licensee  ;

event Report No. 50-29/87-06, subsequent telephone conferences and

io-office reviews. At no time during this inspection was written material

provided to the licensee by the inspector.

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