IR 05000289/1988020

Insp Rept 50-289/88-20 on 880725-29.No Violations or Deviations Noted.Major Areas Inspected:Steam Generator Eddy Current Insp Results & Secondary Side Water Chemistry

ML20151Y840
Person / Time
Site:	Three Mile Island
Issue date:	08/12/1988
From:	Strosnider J, Winters R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20151Y829	List: IR 05000289/1988020 ML20151Y827
References
50-289-88-20, NUDOCS 8808290057
Download: ML20151Y840 (12)

Text

. . , - - - - - - - _ - - - - _ - _ - - - - - - - - - - - - _ - - _ _ _ . - _ - -

_,

. . - ..

>

.,

,

.-

U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Report N /88-20 Docket-N License N DPR-50 Licensee: GPU Nuclear Corporation Post Office Box 480 Middletown, Pennsylvania 17057 Facility Name: Three Mile Island Nuclear Generating Station - Unit 1 Inspection At: Middletown, Pennsylvania Inspection Dates: July 25 - 29, 1988 Inspector: f// h date G//2 /##

1. [ C D

. Wiliters,

, Region Reactor I Engineer, MPS, EB,

,

Approved b _

f, Materials & Processes 8k2lff trosnider, C date tion Engineering Branch, DRS, RI Inspection Sum m : Routine unannounced inspection on July 25-29, 1988 (Report No. 50-289/88-20)

Areas Inspected: The inspection covered steam generator eddy current inspection results, secondary side water chemistry, radiation exposures resulting from the eddy current inspection and repairs of the steam generator Results: The inspector concluded, based on the areas inspected, that the licensee's activities were performed in compliance with the applicable requirements of the Technica'i Specifications and the ASME Code,Section X No violations or deviations were identifie B gDR ADOCK 0 % 299

. - - - - - - - - - - - - - _ _ - - - - - - - - - _ - _ _ _

,

.. ..

O

.

OETAILS 1.0 Persons Contacted

• R. Barley, Three Mile Island Unit 1, Engineering Manager K. Behling, Radiation Control Engineer

• E. Fuhrer, Chemistry Manager

• J. Jandovitz, Inservice Inspection Supervisor

• 5. Otto, Licensing Engineer J. Schmidt, Radiation Control Engineer R. Shaw, Radiation Engineering Manager

• M. Torborg, Inservice Inspection Engineer M. Zeise, Quality Control Outage Coordinator United States Nuclear Regulatory Commission T. Moslak, Resident Inspector, Three Mile Island Unit 1

• Der.otes those attending the exit meetin The inspector also contacted other administrative and technical personnel during the inspectio .0 Introduction Three Mile Island Nuclear Generating Station Unit 1 is a Babcock and Wilcox designed pressurized water reactor unit. It was licensed for operation April 19, 1974 and went into commercial operation September 2, 1974. The two vertical once through steam generators (OTSG) were designed with 15,531 Inconel tubes having a 0.625 inch outside diameter and a nominal wall thickness of 0.034 inches. The heating length of these tubes is 52 feet 1 3/8 inches giving a total heating ,

area of 132,436 square feet. There are fifteen tube support plates

. between the upper and lower tubesheets to stabilize the tube bundl '

These plates have broached tri-lobed holes except at the outer diameter to allow upward flow during operation. The outer diameter holes are drilled. Tube support spacers position and stabilize the tube support plates at various elevations in the tube bundl Full load design temperature is 603 F at 925 psia for the primary sid The units are designed for a steam flow of 5.301X105 pounds per hou Prior to the 1988 eddy current inspection the ' A' and 'B' generators had 1247 and 359 tubes. respectively, out of servic Subsequent to the 1938 eddy current irispection the ' A' generator had 262 degraded tubes of which 19 had defects that grew more than 10*s. The 'B'

generator had 26 degraded tubes of which 5 had defects that grew more ,

than ID*;. t i

!

__. - _ _ _ __-_ ____ -_ ___ -_________ . _____ _______ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

. ..

,

,

s  !

3 l 3.0 References / Requirements

'

Technical Specifications, paragraph 4.19 OTSG Ttbe Inservice Inspection Procedure 1300-48, Revision 3, Eddy Current Examination of OTSG  !

Procedure 1030 Revision ll, Control of Access to Primary and '

Secondary System Openings Procedure 1020, Revision 10. Cleanliness Requirements 4.0 Steam Generator Eddy Current Inspecti_on  !

Scope The results of the eddy current inspection of the OTSGs completed in July 1988 were reviewed and the methods of data collection and analysis was discussed with licensee personnel. Improvements made in the testing techniques to provide better inspection with less radiation exposure were also discusse Details of the Review ,

The inspector reviewed the data from the July 1988 eddy current inspection and interviewed personnel concerning the past inspectio During this inspection 3*4 of the tubes in each OTSG were eddy current inspected and the results showed the OTSGS to be in Technical l Specification category C2. As a result an additional 6*. of the tubes l in each OTSG were inspected and the rtsult placed both OTSGs in '

category C Testing was performed using a standard bobbin probe approximately  ;

0.015 inch diameter less than the nominal tube diameter. When indications of defects were identified a verification inspection was  ;

made using an SX1 pancake probe to further define the defec [

The inspector verified that the correct tubes were plugged by reviewing the videotapes of the tube marking and plugging verification operations for the 'B' OTS l The inspector discussed the methods used during the eddy current inspection with licensee personnel. One improvement the licensee had made during this inspection was achieved by slowing the speed the probes were inserted into the tube In the past the maximum rate of insettion was used to reduce the dead time since the actual test is performed as the probe is withdraw Because of the clearance between the probe and the tube wall is approximately 0.015 total, any obstructions tended to cause the probe to jam during insertion. Such  ;

jamming would result in the licensee (or eddy current contractor)

having a dif ficult time renoving the jammed probe since reversing the I

-

,

_ - _ _ _ _ __

.. ..

.

'

4 1

<

probe drive would often not pull the probe out thereby increasing l inspection time and radiation exposure. By reducing the insertion speed the probes that jammed with one exception were able to be removed with the insertion drive. A further improvement that reduced eddy current inspection time was the use of a drive probe pushing device that allowed switching probes and drivers to a new probe when the one in use was worn or damaged. The licensee reported that receiving inspection of the probes was performed to assure that no oversi:e probes were used during the inspection. This further reduced the problem with jammed probe Results The initial eddv current of the OTSG placed both in Technical Srecification category C2. The additional inspection required by the Technical Specific.ations placed them in Ca:egory C1. Table 1 is a summary of the inspections performed and the results of these inspection TABLE 1 Su mary _of the Eddy Current Inspection Operation Once Through Steam Generator

'gr--

-

rA '

Plugged prior to this inspection 1247 359 Plugged duririg this inspection 13 8 Total plugged after the inspection 1260 - 8.1*. 367 - 2.4*.

Degraded prior to inspectiv (1) 243 21 Degraded after this inspection 262 26 Inspections Required by TS 1653 1425 Tubes inspected (bobbin coil) (2) 2791 - 14*. 1938 - 12',

Tubes inspected (SX1 pancake coil) 311 59 Inspection Results Total defected / plugged 12/12 4/4 Total degraded / plugged (3) 19/1 5/4 Sludge retroyed (pounds) 113 178 (1) primary side IGSCC caused by sulphur intrusion in 1981 (see NUREG 1019)

(2) Includes both initial and second inspectio (3) Tubes that changed greater than 10*. since the las+. examinatio _

d

, _ _ - - - - - - - - -

.. ..

.

Corc'usions

<

The inspection results indicate that the tubes in the OTSG are not acting similarly since the ' A' generator has about 6% more plugged tubes than the 'B' generator. Since the sulphur intrusion in 1981 nc new mechanisms for degradation of the OTSG has been observed. The itcansee is trying to develop innovntive ways to improve the eddy

. .Jrrent testing by using the sicwer speed insertion and dual probe pt:.hers to reduce inspection time and radiation exposure .0 Data Analysis De ails of the Review i

The eody corr 2nt contractor hersonnel were given approximately two and a half days of site specific training prior to being allowed to set up

'- ano perform any eddy current testing. This training included the usual site access training and in addition specific information on the OTSG, types of defects found in the past, specific information on how t3 *eport defects so direct somparisons with prior testing could be macc and information on the evaluation and verification techniques to be used during the data evaluation. The inspector reviewed the records of this training end verified that all data analysts had r'cc hed the it. formation. During the review of the contractor ;

'

certification records the inspector noted that several of the individuals had been at Three Mile Island riuclear Power Station for tne 1986 eddy current inspection of the OTS ,

The Intpector reviewed the certification 9 of selected individuals in the addy current testing contractors (CCNAM) organization. All of the ,

1 irtifications reviewed met the requirements of SNT-TC-1A for the appropriate levels of certificat10H for the tasks these individuals i

'

petforme Tbt contractor had one Level III individual on site for the testing a'6 ditt analysi The inspector c".t tor'ned that all eddy current test results were given two independer r.s .iws by certified analyst If differences between ,

the analysts w' a found the Level III would resolve these difference l In the event the Level III was to reduce the defee.t size reported by l an analyst frcm greater than the plugging limit to below the plugging

! limit, the Level III was required to get agreement from the original

'

analys No licensee employees have oeen certified as Level Il '

The 1isp(ntor reviewed tt ) esults of selected tubes that were deg .dEd in the 1986 inspection and compared these resultJ of those reper ed in the '.953 inspec+. io In all cases examined the two re 2 55 were within the limit of accuracy of the addy current testing metho j i

'

i b

t

r

,, ..

Control of access to the primary and secondary system when these systems are opened is achieved by Administrative Procedure 1030. In accordance with this procedure when the system is open the area around the opening is designated an exclusion area unless exempted by the Shift Supervisor or Shift Foremen for small openings. Only essential tools and equipment are allowed into the exclusion area and the system openin The Jcb Foremen determines the appropriate means of securinu all loose object; carried into the opening. Any small tools that could fall out of sight and be missed during the final inspection prior to closing the opening are logged in and out of the openin When required by the opening size and workscope an individual is assigned to the exclusion area to monitor tools and equipment entering and leaving the opening. During operation ar. accelerometer sensor based in the reactor coolant system and including the OTSGs records unusual sounds for analysi Conclusions The site specific training for contractor personnel was adequate to assure that the results were reported uniformly so that direct comparisons with previous inspections could be made. Contractor personnel were qualified and certified to the appropriate levels as required by SNT-TC-1 The method used for verification analysis of the data was adequat .0 Engineering Scope Ine extent of engineering involvement with t.he OTSG inspection pr agrae was reviewe Ostails of the Review The insoactor inte viewed individuals in the Site Engineering group to determine the scope of their involvement ir the tospection of the GTSG F*en these interviews the inspector determined that the Site Encineering group was responsible for tha initial selection of tubes te be examined. ard if the inspection was to be escalated the selection of the tubes to be examined as a result of tha escalatio The Cor: orate Engineering section is primarily involved with the equipment aspacts of the testing and performs a review function for plugging a1d tube stabi'izatien te assure the oroper tubes were plugged ana stabilize The inspector reviewed the videotapes of the tube marking and plugging operation for the 'B' OTSG to assure that the appropriate tubes had been marked and plugged. The method used for marking the tubes on the top tubesheet was to use the same manipulator used during the inspection to identify and mark tubes to be plugged ard/or stabilize .. ..

l I

1 7 j l

Visual examination to verify that the correct tubes were marked was also employed. Color coding of the marking was used to identify tubes to be plugged only and a different color for tubes to be stabilize Stabilized tubes had a length of tubing inserted and anchored in the area of the defect to prevent the tube from whipping if it failed even though it was plugged. To assure that the same tube was marked on the bottom tubesheet the licensee inserted a probe through the marked tube from the top and had an individual mark the bottom end where the probe exited. The inspector reviewed the videotapes of the marking and plugging operations for the 'B' OTSG to assure the correct defective h- had been marked and plugge In all cases observed the correct

.sv.e had been marked and plugge Conclusions Site Engineering was airectly involved with the selection of tubes to be inspecte The videotapes clearly indicated which tubes had been marked and plugged and were relatively easy to follow based on the location of previously plugged tubes that were easy to see on the tape. The method of marking the bottom tubesheet to find the same tube was positive but did require that individuals involved be immediately outside the OTSG bottom opening and therefore exposed to relatively high radiation field .0 Secondary Water Chemistry Scope

'

Wattr chemistry data was reviewed as part of the steam generator maintenance program. The methods of collecting and verifying the accuracy of these data were nct inciuded in the scope of this inspectio Details of the Review The plant has been operated with all volatile water treatment (AVT)

since initial operation with hydrazine additions to control the pH and oxygen. Durir.g the last two months of operation bef ore the refueling outage the licensee was experi.menting with morpholine for pH and oxygen control and to assist in reducir.g the sludge builaup on the GTSG tube support oiates. During this outage the results of this experiment were inconclusiv Typically this buildup occurs on the third and fourth support plate from the bottom of the generator. To remove the buildup the licensee uses a water ' slap' technique to loosen the sludge followed by lancing for removal. The water ' slap' consists of lowering the water level to below the support plate to be ' slapped', then injecting nitrogen to cause the water to slap the support plate from belo This technique serves to open the flow passages in the support plates allowing improved flow during operatio . . .

. . .

,

.

.

The licensee does extensive sampling of the secondary water at the following points in the system:

--

Condenser hetvells - nine sample points have been established for cation conductivity to aid in locating condenser leaks if any

.should occu '

--

At the condensate pump discharge there are in-line monitors for specific condu:tivity, cation conductivity oxygen, sodium and pH and grab samples can be taken at this poin Cation conductivicy is measured in each of the condensate demineralizers

--

After the condensate demineralizers cation conductivity, sodium and pH are measured with in-line monitors and there is a grab sample station at the monitor Specific conductivity and o>.ygen are measured after the low pressure feedwater pumps and before the low pressure feedwater heater Located between the high pretsure feedwater heaters and the OTSG are on-line monitors for sodium, cation conductivity, oxygen, pH, and hydrazine. There is also a grab sample point at this locatio In the main steam line there is a sample point for dose eauivalent I-131, Tritium, sodium, pH and silic The inspector reviewed selected portions of the above samples to determine if the results are consistent with the EPRI guidelines for OTSGs. The results of this review are shown in Table ,

,

d

, -- -- . , . - . . - , -,,n ,,- --- -. ,,,_ -, .-- ~, ,-. , -.- - ._,g,~ , , ,,,n , , -

,,,,,,,_,,,e

,. ..

l

.

i 9 l TABLE 2 Secondary Water Chemistry Results Location and Perameter Licensee .

.EPRI Results Guideline Condensate Purap Discharge Chlorides (ppb) 1 0xygen (ppb) 11 Specific Conductivity UMH0/CM 5.85 Catton Conductivity UMH0/CM 0.135 Socium (ppb) 0.4; p!1 9.41 Feedwater Chlorides (ppb) 1 5 max Specific Conductivity UMH0/CM 5.78 Cation Conductivity UMH0/CM b.092 0.2 max Sodium (ppb) max 0xygen (ppb) max pH 9.44 9.3- In the last two years the licensee has upgraded the chemistry laboratory equipment by adding or upgrading the following equipment:

--

Replaced three sodium analyzers

--

Added a portable oxyger. analyzer and upgraded two in the laboratory

--

Dedicated an ion chromatograph for use fn determining secondary side water chee.istr Conclusions The licen:ee has mairtained the secondary water :hemistry parameters within tne EPRI guidelines during periods of normal power operatio '1ese benefits of good water chemistry control are reflected in the results of the eddy current testing described abov f

_

-

.. ..

.

~

8.0 Radiation Exposure Scope Radiation data was reviewed as part of this steam generator inspection and maintenance program inspectio The methods of collecting and verifying the accuracy of these data were not included in the scope of this inspectio f.e1 ails of the Review The inspector reviewed the radiation expt ure data for the 1983 OTSG eddy current inspection and discussed the efforts used to reduce this exposure with licensee personnel. Mock up training is used to prepare the individuals for tc.e type of operations and access limitations to be expected during the inspection and repairs to the OT5G. The results of these reviews are shown in Table TABLE 3 Sut. mary of radiatica Exposu_r_es During 1988 Inspection Units are Man-Rem Operation Total Exposure Both Generators Installation and removal of manways 5.6'

All eddy current testing operations Wcter slap and lancing Repair - tube plugg:ng stabilizer installatio .8 Visual inspection before closing OTSG All other cperations Total 2 Conclusions The licensee has improved the metheds used in eddy current testing by the use of dual probe pushers, slower insertion speeds and trainina in the mock-up. Ali of t'ese actions have tided in reducing exposures during the eddy current inspection and repairs of the OTS .0 Licensee's Actions on Previous NRC Concerns (Closed) Unresolved Item (86-13-06); Seismic atslysis of the l modificatien to Westinghouse 08-25 and 08-50 Breaters.

i

1 i

!

,. ..

.

i The inspector reviewed the amendment to the Amptector generic qualifica-tion report (WCAP 10449) for the modification to the Westinghouse 08-25 and 08-50 breakers. The seismic analysis had been verified as adequate for the modifications performed on these breakers including the mounting bracket desig This item is close { Closed) Unrasolved Item (86-19-02J1 Seismic mounting of conduits and a dome., tic water line above the Category I two hour backup air supply in the 'B' diesel generator roo The inspector reviewed the Plant Inspection Report (CS/33730/87) for the inspection of the welds and bolt torquing of the support connections for the conduit above the two hour backup air supply. The engineering analysis (memo 5320-87-2064) of the support for the 1/2 inch don..stic water supply piping in this same location was reviewe The inspector had no questions as to the adequacy of the seismic raounting of these item This item is close [ Closed) Unresolved Item (86-22-d311 Removal of couplant after manual ultrasonic examination of stainless steel piping weld Procedure 6110-QAP-7209.06 required removal of couplant only if the stTinless steel piping examined was operating above 150 F. Since the inspection personnel d'd not necessarily know, nor were they required to know, the operating conditions of the piping they examined this i left in doubt whether all piping operating over 150 F was cleaned as required. The licensee revised this procedure to require the couplant be removed from all stainless steel piping after all manual ultrasonic examination This item is close .0 l'nresolved Items Unresolvec items are matters about which more information is required in order to ascertair, whether they are acceptable items or violation Unresolved items are oiscussed in paragraph .0 Management Meetings Licensee management was informed of the scope and purpose of the inspection at the entrance interview on July 25, 198 The findings of the inspection were discussed with licensee representatives during the course of the inspection and presented to licensee management at the July 29, 1988 exit interview (see paragraph 1 for attendees).

-- - _ -

, . .

.- *.

.

t

.

At no time during the inspection was written material provided to the licensee by the inspector. No proprietary information has been included in this report.