IR 05000313/1975011
| ML19326B454 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 11/05/1975 |
| From: | Donna Anderson, Herdt A, Madsen G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | |
| Shared Package | |
| ML19326B448 | List: |
| References | |
| 50-313-75-11, NUDOCS 8004150801 | |
| Download: ML19326B454 (12) | |
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U.' S. NUCLEAR TEGULAIORY CCCIISSION gj.
REGION IV
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OFFICE OF INSPECTIO:: el;D E ;rCF.'.,DT::T
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IE Inspection Report No. 50-313/75-11 Docket No. 50-313 Licensee: Arkansas Power & Light Cenpany.
License No.: PPR-51
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Sixth & Pine Streets Pine Bluff, Arkansas 71601 Category C Facility: Arkansas Nuclear One, Unit 1 Location: Russellville, Arkansas
- Type of Lic mse: E&W, PWR, 2568, Mut Type of Inspection: Management Meeting, Announced
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Dates of Inspection: October 10, 1975 i
Datos of Previous Inspection: September 23-25, 1975
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Frincipal Inspector:
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D. G. Anderson, Keactor' Inspector, lE:1V I :tc i
Other Accorpanying Personnel:
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L. :'adsen, Chief. Peactor Cunstruction &
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A. R. Herdt, Metallurgical EnEinc er, IE:11 f t.c 4-
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Revicwed By:
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L.1:adwn, Chief, Kuctor C nstructicn ano
'cLe Operation *; Eranch, IE:IV i-r i
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SC! MARY OF FINDINGS V
A.
Enforcement Action-None identified.
B.
I.icensee Action'or Previously Identified Enforececnt Itens Not inspected.
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C.
Design Chances
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Not inspected.
- D.
Unusual-Occurrences Not inspected.
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E.
Other Significant Findings Previously Unresolved Itcrs
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f 74-14/7 Reactor Buildinr, Sprcy Line Cr."cks A complete pnchet of infort ttien uith ctter.'cnt cus:;csted corrective acticn will be supplied by the licerece by 00tc :.cr 31,1975. Ynic submittsi trill
be considerci by ::RC (IE:1V) cs i.M.L'.s flual evcluation of this pr: vle:.
(DETAILS, parcgraph 5).
F.
Management F.it Interview Ca October 10, 1975, et the conclurton cf this car.a y.m.nt r:cting, ac represent..:.iva nf the ::Rt. t ~ = d zed ci... diret.s:,;onc cence r.i k g re clutien
of the prob 1trs relate.d to t% ;-ipe err.chs ubich have r,ccm :
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1 Reactor Evi2 ding Eprcy Sycu u w.th '.. ii. Cavaunuah, i cher of Ir ctaff,
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and representatives of Eechtel carparction. The follm-i:.; *: ens.v e
discussed during the court.c of the c.:lt interview:
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1.
The purp<:se of arrannl. g this tecting.
(DETAILS, parter.ph 2)
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2.
The hiutory of the pipe cracks in the Reactor Building Spray Jirec.'
I (DEfAILS, paragrcph 3)
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3.
Sa:cpling techniques and colutien chemictry.
(DETAII.S. parr.;;rnph 4)
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4.
Anticipated co nitacnts of the licensee toward rer.olution of the Reactor Euilding Spray Line crack problem.
(DETAILS, paragraph T,)
(continued)
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DETAILS V
1.
Persons Centacted Arkansas Pover'and Light Company (AP&L)
.W. Cavanaugh, Manager, Nuclear Services N. A.. Moore, Manager,. Quality Assurance G.-H. Miller. Assistant Plant Superintendent
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D. A. Rueter, Licensing Engineer D. R. Sikes, Production Project Supervisor D. Willicas, Assistant Engineer
C. L. Bean,-Quality Assurance Inspector R. D. Lane, Assistant Production Project Supervisor G. G. Young, Assistant Engineer Bechtel Power Corporation E. H. Scith J. J. Oszewski-H. L. Leichter Yun Chung l
Nuclear Regulatory Commission
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G.-L. Madsen, Region IV
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D. G. Anderscn, Tagion IV
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m A. R. Herdt, negfon II 2.
Purpene of thic Meeting i
This tecting vitL the tcnagement of AP&L was scheduled in ord.r to revi a the past hirtrry of acticn taken by the licensee with re;urd i.o I-
- ar Building S; rcy Mne crachs (74/11.-7) and to encourage a cecnic.cnt.- cr the part of AP&L te.ccutinued surveillance and future replccemcnt of th:
defective -p!pf t:3 c c ANO-1.
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3.
Reactor riui.lding Spray Line Crnck Chronology
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This problen *:ns first notrd during routine surveillance on Neverbcr 8, 1974 (Sc6 Apre-dix A for refereu.c material on this subject). The fit:al reports on :bs ;ir:Aler. vere received from Bechtel and Southvcst h u.trch
Institute cn' August 5, 1975. An ar.alysis of the poct ulated fcil"rc of this pi; ins L s been condoct24 f: Eechtel by Failure Analysia Arec:farcs.
This1rept:t wai. reviewed daring the canagement caeting ::.d the 1:ceurce's
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represer.tative indicated that a final version. vill be srbuitted to lE:!T
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by October - 32,.1575.
Ibis cnnlysis ac1ures a 2-inch long through.a21
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crack in ocLndule 10 r: ire with the tat trial properties of the 800:01 affected heat.
Initial cct.diticas asauned include stress levels :a cd:d to cause che exicting crach to go critical. The results of this c.nnlysis
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indicate that stresses 12 tices greater than.these postu*ated would be necessary to cause' failure. Also, for the stress 1ciels poctulated
.in this analysis, a 5.6-inch'long crack would be neccesary for the existing crack-to fail..Three conditions were evaluated in this
' analysis:
' Straight Accident
_ Operating Basis Accident
- Design Basis _ Accident
~The final report on this accident analysis will complete the licensee's-
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evaluation of this problem area.
4.
' Chemical Analysis The licensee indicated that a procedure supplied by Allied Chcniccl-Corporation is being used to neasure the concentration of chlorides in
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the spray.colution in the building spray lines. The 11cen e indicated confidence in the results of chloride concentration using this precedure.
The licensee indicated that sampling and flushing of these lincs 13 routinely performed on a quarterly basis.
If chloride concentrction
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exceeds 10 ppm, then the lines are flushed until additional satpling
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results indicate a chloride concentration lecs than 10 ppn.
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Anticipated Licencee Action
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The licencoc indiccLed at the conclucien of this canogetr>nt cceting that a_co=plete packet tvuld be submitted to IE:IV by October 31, 1975 containing the folicwing infernation:
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The failure analysis final' report.
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A surveillance progran consisting of qunrterly rcquiremente of fluthing j
and sary. ling the affected line s, an attnual '.'JT of the affected relJa s
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a sar.pliur, basis, and visual inspections of the affected pipe on a j
once per shift basis.
Commitc?nt to replacing the affected pipe in the event any additional c.
leaks appear.
The inspectors indicated that this ceditional information could be considered as the final evalnation by AP&L on this problen and would be reviewed by IE:IV prior to cubuittal to 131 with our cettents for action.
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IE Rpt. No. 50-313/75-11 II-l-(
DETAILS II~
Prepared by:
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A. R. Herdt,-Metallurgical Engineer Date Engineering Section Facilities Construction Branch Dates of Inspection: October 10, 1975 D-
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Reviewed by:
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L. L. Ecratan, Senior Inspector Date
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Engineering Section Facilitics Construction Branch
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Personc Contacted a.
Arkansas Power and Licht Company (AP&L)
G. H. Miller - Assistant Pinnt' Superintendent W. Cavanaur,h - Manager, ;;ucicar Services C. L. Econ - OA In:,pcetor
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Contractg Organization
(1) Bechte] Corpor:: tion (Deratel)
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E. H. Snith - Pr jcet Mar.ap,er
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J. LJ. Daze:: ski - PJ nid '.;f ncer i
II. L. Le.!chter - :'." s11:.raical Engineer l
Y. ' Chung - Met.mi 'ar c.J ul F.ngineering Specialist (2) Sna t,'get Resgg y ;..i.f;tte (Ser.Q
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H. C. Burghard, Tr. - St ator Rescsrch Engineer *
- Mear.ung on Ms, 19-20, l!75
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Scope of Tur,weth
~The purpose 'of t:hh incpectica t'as to meet vith APLL tranagercat to discuss the icvert i :atica or the ccac! cd welds in the 10-inch
t schedula 10 (u.10.i vall) rype 304.;trinier.u steel piping of the Reactor huilding Spray Sysr.e.:n in the Arkanus Nuclear One, Unit No.
- 1. - The prireary ite.ns discusacd tic re:
the.;etallurgical investigations
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'perforr.ed by Battelle Coj u:abus Laboratory, Bechtel Corporat. ion and-Southwest Ressarch Institute; and the propo. sed corrective accion by AP&L.:
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IE Rpt. No.-50-313/75-11 II-2~
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.This report covers the inspection'nade at Southwest Research Institute on May 19-20, 1975, to view the ectallurgical examinations being conducted as a result of these cracked welds and the-nceting with AP&L management personnel at Little Rock, Arkansas, on October 10, 1975.
.3.
Metallurgical Investigations.
a.
Background As previously reported in IE Report Nos. 50-313/74-14 and 50-313/74-15, leaks were discovered in the Reactor Building
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Spray Sycten B loop pump suction piping of Arkansas Nuc1cnr
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One Unit No. 1.
This was reported in Abr,crual Cecurrence Report No. 50-313/74-11B. Since the leak.< involved the same heat (No. 600201) of stainless stocl material, the licensee initiated a program of exaaination of ucids including the heat affected zone of the-pipe of the above heat nucher.
In addition, an increased visual surveillance program was initiated to -
search for additional leaks. A random selection of areas adjacent to 46 welds (both chop and field) in the same heat of pipe in the reactor building spray and decay systems was
"~s exaulned by radiographic cethods. This is discussed in detail in IE neport !!o. 50-313/74-15.
Metallurgical exsminatioc. of
,\\s-these crauku uas performed by Eattelle Columbus Laboratories
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and Bechtel Corporation uith Southwest Research Institute performing core totallurgical examination under contract to l
Bechtel cerectation.
.b.
Battelle COSchus Laboratories (Battelle)
Battelle Cob ubus Laboratories, under contract W-7405-Eng-92, to the t:ucl. ir llegulatory Conmission, performed an indepcadent
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metallurrie:1 examination of a portion of the cracked welds in the.30-in:b Type 304 stainicss steel piping taken from the Reacter f.uilding Spray Evaten. The leak examined was a portien of number 2 as relaLcd to Bcchtel'interin report. The purpt.cc
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of Matteb e's independent examination was to verify and audit
.the tctallurrical exatination provided by the licensee. The
~ inspector visited Bat:cIle on December 13,'1974, as described in IE Rpt. 1:a. 50-313/74-15, ' Details II, paragraph 3.C.
Battelle completed their independent examination on February 7, 1973, and the report'is included as an Attachment to these details. Battelle's results indicate that the leaks were the result of intergranular stress-corrosion cracking that was:
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IE1Rpt.LNo. 50-313/75-11 11_3
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initiated on the inside of the piping and propagated inter-granularly through the sensitized microstructure of the heat-affected zone adjacent to the veld. The probable source of stress was excessive residual stress from weld repairs or high
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heat input during welding. Chemical analysis revealed the piping _was within chemical specification, even though the
. carbon-content was near the upper limit for Type 304 stainless
steel. Battelle performed a semiquantative ion microprobe
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analysis of selected areas on pieces from the 10-inch pipe, namely the heat affected zone, center of the weld and the fracture surface. This microprobe as well as the scanning electron microscope analysis revealed up to 1000 ppm chloride ion at the heat affected zone on the inner surface of the pipe as well as on the fracture surface itself.
Appreciable quantities
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of sodium, aluminum, silicon, and calcium were also found.
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Battelle stated in their report that the probable corrodent was the chloride ion, however, the source is not defenitely known.
c.
Southwest Research Institute (SwRI)
The inspector met with Herman Burghard, Jr., Senior Research Engineer, Department of Ibterials Engineering, SwRI en the
[,_sj May 19-20, 1975, to review his metallurgical investigation plan (s,/
and results to date. There were no representatives from Bechtel or Arkansas Power and Light Company present during the inspection.
(1) Background SwRI has been retcIned by Bechtel to act as an independent third party in this thin wall pipe cracking probica.
SwRI has been retained to perform the following work:
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-(a) Review the analysis perforced in the Bechtcl laboratory.
(b) Establish a program to examine, in the ficid, pipe surf ace conditions and to identify pipe that has
cxperienced chemical attack due to excessise pickling.
(c) Perform an independent metallurgical examination of cracks 4, 5 and 6 as uell as radiographic indications following rencval of the crossover pipe.
In addition, a sample of a shop fabricated weld and a field
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fabricated weld exhibiting no cracking characteristics will also be netallurgically examined. These samp]cs are from the crossover section.
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IE Rpt. No. 50-313/75-11'
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(d) The surface of the pipe will be examined in the field for carbide precipitation.
It is noted that the work performed in Nevenber 1974, was premature since carbide precipitatica was noted only at mid-wall. The ID and OD surfaces exhibited no carbide precipitation.
Based on these results, trepan and ring samples were taken from existing pipe of the reactor building spray systen and decay heat system to determine whether carh;de precipitation existed,
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and to determine the base retal characteristics.
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Item (a) had been completed with regard to the review of the metallographic results on Leahs 1-3 and was incorporated in the supplemental rcport forearded to the '.KC on February 5,
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1975. SwRI concurred that contributing far. tors to the cracking vore base =ctal pickling, high carbon content and base metal sensitization.
Item (b) had been completed and the results indicata that all pipe examined regardless of size, heat number or r:anufacturcr exhibited some pickling attack.
Items (c) and (d) was presently being perforr.ed.
The status and details of these itens are discussed below:
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- (j (2) Metallurgical Rosalts (a) Crack Sanples
SwRI performed a detailed meta Jurgical enaminat:en of cracks desirmted 4, 5 and 6 m. w A l as one t.zid that shoced an indicativo of a i. ch in the rndiegraphy perforced in Ncvember 19M.
In additloa, a scnple of a shop fabricated we]d and a ficid'inbricated t
wc3d exhibiting.no cracking char cteristics to be classified as typical was alno retallurgically ennained. All are fron the croc. cover area.
Upon receipt of these snr.ples, SwRI took laboratory
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radioyraphs of all the r.anplea.md perforned a liquid penetrant inspection of approximately half of thec : samples to deter =ine whether by.these nondestruc-tive test nethods cracking could be observed.
Crache were detected on all the samples by both of these cethods.
The inspector revicwed the radiographs
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cad L: c cracks could be easily identified located adjaa ut to the wcld running circumferential1y in the bec.t affected zone.'
In most cases the cracking
uas continuous in nature.
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IE Rp t. No. 50-313/75-11 II-5-(
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SwRI had begun the metallographic investigation on crack 5, radiographic indication, the shop and field fabricated wcld saeples.
Preliminary results showed that.the four samples exhibited cracking from the ID toward the OD, intergranular in nature, in the sensitized heat affceted zone and the base =ctal
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contained a mid-wall sensitized zone. There is no difference metallurgically from what is seen in these samples and what has been previously reported by Battelle and Bechtcl. Crack 5 and the radiographic indications showed through-wall cracks while the
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field fabricated and shop fabricated welds showed cracking approximately 3/4 through the tube wall.
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The inspector reviewed the metallurgical data including the metallography and concurred with these preliminary findings.
(b) Base Metal Samnles As previously stated, trepan and ring base metal samples have been taken from existing pipe of the reactor building spray system and decay heat system.
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These samples arc of different sizes and heats as
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well as the original heat in question, SL'EPC011 eat
s No. 800201. A preliminary listing shows ten heats and six different pipe sizes.
SuRI has - started the =ctallurgical investigation on nine samples for base metal analysis. To date the only heat to chew mid-wall sensitization-is licat No.
800201;'the 1G-inch diameter pipe of this heat is
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the only size that has been examined at this point in time.'
'1he inspector revieued these preliminary
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findings with no ditferences being uncovered.
(c) Sumnary
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The SwRI natallurgical report was included in the
" Investigation of Pipe Leakage, Reactor Building Spray System Piping, Arkansas Nuclear One, Unit 1 Final Re; ort" dated August 15, 1975, forwarded by AP&L letter dated August-29, 1975.
Besides the independent third party work performed by SuRI, the metallurgical investigation performed by Bechtel was
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also included.
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.The inspector reviewed and analy=ed both of these metallurgical investigations as well as the Battelle report.. 'The conclusion reached by all three studies
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are. metallurgically similar and are as follows:
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~The mode of failure of the Type 304 stainless steci
was found to be stress-assisted corrosion cracking propagating intergranularly through the sensitized
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microstructure of the heat-affected zone adjacent to the circumferential welds.
- The sources of the' stress were residual stresses associated with welding; sentization in the heat-
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affected zones near welds produced by welding heat, possibly high heat input; and chlordde ions and/or
sulfur-oxide ions as a corrodent.
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Other factors in the stress-assisted corrosion cracking failure were: high carbon content of-the piping material at the maximum permitted by the
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specification, and partial sensitization of the piping material (HT 800201, SWEPCO).
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In summary, the metallurgical reports are in agreement as to the
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. piping fa'ilure mode. With: regard. to the metallurgy, there are no
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major questions or additional metallurgical suggested work required.
'4.
Management Meeting-The inspector together with representatives from IE:IV net uith
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t AP6L muungement and their representatives in Little Rock, !.rkansas,
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-on Octobcr 10, 1975. The taajor area of concern is the corrective
action prepoced by AP&L; periodic surveillance for leahr in pipe
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containing sensitized structure (!!T 800201 and 2P-3352); whether
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the piping will be eventually replaced; and the licensco's overall j
corrective action program.
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The inspector stated that the'netallurgical reports were in general-agreement as to the cause and mode of the wcld failures and cracking.
- The licennee reported that the final report would be submitted to the NRC by October 31, 1975.
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- The. licensee stated that this final report would include as a minimum the following
The extensive study by Failure Analysis Associates on a postulated
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crack in'the Schedule 10 piping under design stresses.
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IE Rpt. No. 50-313/75-11 II-7.
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t b.
Full description of the walk-through surveillance including the procedure, frequency, and records.
c.
Sampling of the borated water in the Reactor Building Spray.
System including.the chloride acceptance level with its justif-
'ication,-the sampling procedure and assurance a representative sample:is taken.
P d.
Periodic volumetric inservica inspection programs including the procedure frequency and method for the piping systems
- containing material from Hect No. 800201 and the section of sensitized piping associated with Heat No. 2P-3352. The inspector point out that if radiographs are used as the volumetric inspection that the baseline radiographs meet code
requirements and that the offectiveness of the radiography as to defect size be discussed.
-1 The Office of Inspection and Enforcement will evaluate this final i
report and make any necessary recer.nendations.
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' APPENDIX A
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1.
Abnormal Occurrence Report No. 50-313/74-11, J. D. Phillips, AP&L to N.
C,. Moseley, RO/II, November IS, 1974.
2.
. R0 Inspection Report No. 50-313/74-14, November 29, 1974.
. 3.
IE Inspection Report No. 50-313/74-15, January 6, 1975.
4.
Abnormal Occurrence Report No. 50-313/74-11A, J. D. Phillips, AP&L to N. C. Moseley, IE/II, February 5, 1975.
5.
Examinations of portions of the Reactor Building Spray System Piping from the Arkansas.Juelear Plant No. 1, Battelle Laboratory Report dated February 7, 1975 (26 pp).
l 6.
IE Inspection Report No. 50-313/75-2, May 2, 1975 i
7.
Followup Report - Abnormal Occurrence Report No. 50-313/74-11, l
W. Cavanaugh, AP&L to N. C. Moseley, IE/II, April 11, 1975.
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IE Inspection Report No. 50-313/75-04, May 23, 1975.
9.
IE Inspection Report No. 50-313/75-06, July 3, 1975.
10.
Investigation of pipe leakage, Reactor Building Spray Syctem Pipi:m,
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Arkansas Nuclear One, Unit 1, Final Report Bechtel Corporction, s-August 15, 1975.
31.
Metallurgical Investigation of cracking in reactor safety-relat.^d piping system, Arkansas Nuclear One, l' nit 1, Pinal Report, Southwest k rce.rch Institute, July ll, 1975.
!
12.
_ Abnormal Occurrence Report No. 50-313/74-11E, J. D. Phillips, API:L to B. C. Rusche, HQ/NRR, August 29, 1975.
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