ML19260D385

Responds to NRC Requesting Info Re Water Hammer Events.Water Hammer Event on 791219 Occurred in Isolation Condenser Supply Line & Portions of Return Line.Duration Was Approx 20 Minutes

ML19260D385
Person / Time
Site:	Millstone
Issue date:	02/01/1980
From:	Counsil W NORTHEAST UTILITIES
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19260D377	List: 05000245/LER-1980-003, Forwards LER 80-003/03L-0 & 05000245/LER-1980-003-03, /03L-0:on 800104,operation in Degraded Mode Permitted by Limiting Condition for Operation Occured When Isolation Condenser Was Removed from Svc.Insp Revealed That Supply Line Support May Not Meet Safety Factor Requirements ML19260D385
References
NUDOCS 8002080642
Download: ML19260D385 (10)

Text

{{#Wiki_filter: ' N0lM'M35Jt!iT UTil.lTil!!; U.SS$N[' ',^'",E.'" P.O. BOX 270 i.. -I HARTFORD. CONNECTICUT 00101 y a mov s. w m r.sc*e c w...w ( * "'" .~.....,'v..Oll,?llle' ~,. .C'.U <j, \\ February 1, 1980 Docket No. 50-245 Mr. Boyce H. Grier, Director Region 1 Office of Inspection and Enforcement U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

Reference:

(1) B. H. Grier letter to J. F. Opeka dated January 14, 1980. Genticmen: Millstone Nuclear Power Station, Unit No.1 Isolation Condenser System In Reference (1), Northeast Nuclear Energy Company (NNECO) was requested to furnish information regarding the water-hammer events in the steam line between the reactor vessel and the isolation condenser and subsequent damage assessments, evaluations, repairs, and applicable stress analyses. Accordingly, the following is submitted in response to this request. Item 1.a A description of the location within this system where water hammer events have occurred, their duration, and any observations of magnitude as determined from monitoring of plant instrumentation and parameters.

Response

The water hammer event of December 19,1979, (Reportable Occurrence 79-87) occurred in the isolation condenser supply line and portions of the return line. Duration of the event was approximately twenty minutes as determined by the oscillations in the isolation condenser shell' side water level. There is no instrumentation on this system capable of monitoring the magnitude of dynamic loads such as those produced by water hammer. Item 1.b A description of the extent of visual observations and examinations of damage including displacements and deformations, loose bolts, cracked or spalled concrctc, cracking of insulation, bent hangers, etc. 1934 175 8 Q () ()'2 0 8 0

2-Respo nse A visual inspection of the isolation condenser piping outside the drywell was conducted on December 19, 1979. The following observations were made. The anchor bolts on supply line restraints TES-S and TES-7 were pulled out of the concrete by 1/16 to 3/8 inch maximum. Anchor bolts on return line restraint ICHR-2 were loose and the threaded rods on a deadweight hanger werc bent. Minor damage to the insulation was observed in the areas of floor penetra-tions and axial restraints. Cracks in the concrete around penetration X-10A were noted but did not appear to be significantly greater than when first identi-ficd under 16E Bulletin No. 79-02 in June, 1979. No other evidence of damage was noted. A visual inspection of the isolation condenser piping inside containment was con-ducted on December 20, 1979, with no damage to the piping, valves, supports, or insulation observed. The visual inspection of the concrete was performed by Tcledyne Engineering Services (TES) and their observations are contained in the attached.TES letter 3815A-1 dated January 10, 1980. Item 1.c A description of the extent of non-destructive examinations and their results for piping and structural welds, bolts, and other componcats.

Response

T Non-destructive examinations were performed in accordance with ASME Section XI, Class 2, as follows: Piping Volumetric examination of select high-energy pipe break welds downstream of containment penetration X-10A. Liquid penetrant examination of select circum-ferential welds. Strut.ie Liquid penetrant examination of structural attachment (chcar lug) welds for restraints ICHR-4 (TES-1) and TES-5. Magnetic particle examination of structural welds on the anchor at containment penetration X-10A. Anchor Bolts Tension testing of approximately 30% of the bolts on the anchor at containment penetration X-10A. Torque testing of restraints TES-5, ICHR-5 (TES-7), and ICHR-2. Results of all non-destructive examinations were satisfcctory with no reportable indications. Concrete anchor bolts were satisfactorily tested to one-fourth ultimate in accordance with the requirements of 16E Bulletin No. 79-02. 1934 176

r* _ 3_ Item 1.d A description of observations as a part of destructive examinations such as after concrete chipping and removal.

Response

Tcledyne Engineering Services (TES) visually inspected the concrete af ter removal of da'maged and loose concrete on January 7 and 8,1980. There was no evidence of structural damage to the wall, ceiling, or concrete column. Refer to the attached TES letter 3815A-1 dated January 10, 1930 for additional information. Item 1.e Results from any other testing such as bolt torque or yull tests.

Response

All concrete expansion bolts on the supply and return line supports / restraints with the execpeton of the penetration anchors were ins;ceted and tested or re-placed in accc dance with the requirements of I&E Bulletin No. 79-02 in June, 1979. In addition, select welds on this system vere volumetrically examined under the augmented inservice inspection program in 1978 and 1979 with no reportable indications. It em 1. f L Evaluations of the extent of damage as indicated by a ihrough e above.

Response

Examinations and testo performed to date indicate no degradation to the system as a result of the water-hammer incident. The Teledyne evaluation of the anchor in their January 10, 1980, letter 3815A-1 indicites that the integrity of the anchor has not been compromised. Tne damage described above can, therefore, be considered of minor consequence and did 7.ot aff ect system safety. Item 2.0 A description of the analytical approach and the results c' piping, nozzle, support, and other system component stress analyses o include scismic, thermal, water hammer, dead weight, and high energy pi e whip type affects. ?

Response

a. Present level of analysis: Supply line - analyzed using the ADLPlPE computer program for deadweight, thermal and seismic load cases. Resulting stresso are within Code allowable limits. 1934 177

_ 4_ Anchor at Contain=cnt Penetration X-10A - analyzed by Teledyne Engineering Services (TES) using the structural analysis computer program "STRUDL". A description of this analysis and the results are provided in the attached TES letter 3815A-2 dated January 21, 1980. b. Additional analyses: Currently, force-time history loads are being developed for water hammer and selected circumf erential break locations. These loads will then be included in the system piping analysis using a forcc-time history option. Resulting stresses in the piping and loads on the supports will then be evaluated. Necessary modifications to the system support scheme will be detennined at that time. Item 3.0 Procedural and administrative measures that you have implemented to prevent water ha=mer from recurring.

Response

Change Number 1 to Millstone I Station Procedure Number OP 502B was initiated on January 9,1980 to administratively control water level in the reactor pressure vessel. In addition, specific guidelines regarding reactor water level control were provided to the operators. Note the referenced procedure change is not applicable during a LOCA recovery. Item 4.0 A description of past and planned modifications and design changes to insure that this system can withstand water hammer eff ects.

Response

In March,1978, two existing restraints were modified and a .rd added to preclude excess movement of the isolation condenser supply line under dynamic loads. Currently, under the direction of TES, the containment penetration anchor is being modified to insure an acceptable factor of saf ety in the concrete anchor bolts. The need for additional support modifications will be determined upon completion of the system analysis referenced in the response to item 2.0 above. Required modifications, if any, will be installed in an expeditious manner. Item 5 0 A description of measures that have been accomplished or that are planned to insure that the impact of discrepancies discovered as part of evaluations and analyses discussed above (i.e., inadequate initial evaluation of concrete cracking, concrete expansion anchor bolts not originally included as part of I&E Bulletin No. 79-02 followup, not including pipe whip ef f ects in analysis of cupport loads) have been properly considered in licensee work and responses to recent I&E Bulletins such as 79-02 and 79-14. 1934 178

Response _ The containment penetration protection anchors were excluded from the I&E Bulletin No. 79-02 program because all the bolts were believed to be embedded concrete anchors. At this time, it is f elt that this oversight is unique. Penetration anchors which use concrete expansion bolts will now be incorporated into the 79-02 program. The detail drawings of the anchors which were not ~~ available for the as-built inspection will be reviewed for discrepancies in accordance with 16E Bulletin No. 79-14. Pipe whip loads were not excluded from the analysis of any support where they were specified as an original design load. For the containment penetration anchors, pipe whip eff ects were considered in the original design and as such, they would be included in the I6E Bulletin No. 79-02 analysis. Supporting documentation de m.ailable at the Millstone Site for your review. NNECO trusts that this information is responsive to NRC Staff requests and Concerns. Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY / /. 9. ET)MM W. G. Counsil Vice President Attachment e 9 1934 179

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1 A 0 9 ,'.38.1.5 % 2.. i ;'~ ';4f-D .t'...' ..f ;...', , if. q.. '.. jb.5 : ',i, l.' f. Mr. Eric' DeBa a Northeast: Utilities Service Ccr.:pany-. .R i '6.' :, 7,.';;. P P.O. Box 270 - A W' Hartford.!CT 05101 h i ){,ke?:t.: .' c

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Subject:

l' Isolation Condenser System,. Anchor X-10 [;5'['. } .. i[<[j g k,.,. 3.89... ....,s Dear Eric.- ,7 A i l.) ? m.s Telehyn.e Engineering Services has:ccepleted analysis of.themdified. r a ~ anchor X,10 for the following loading conditions. .,p.g.; Q'n... h .k.,'^. .a, li ' poraal operation + DBE 9,j. .. :g )..!f.;.if f :;j..d

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..r. ~ The il' ads for the above conditions 6~ e given in :ttachment.~Ho; t.J. i.. i o r 7 Condition 1 J1oads teere supplied by itOSCO and include DDE ond ;fiffects.g } Condition: 2 locos tere taken froa the ' original Etts:' analysis E6f: thel.- subject anchor. In performing the' analysis for Condition 2,\\TES: applied all HEPB loads sieultaneously assuning they could be + r. which could only be applied in the -X dL ection. The c atervatism;of thi - e approach is established in our lette,

i. 3815A-1 date:

b Januar41%.1980. The codified anchor is shown on 'the following TES drawings. d. .v.

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A-5182 Sheet 1, Rev. 3 .P. A-5182 Sheet 2.Rev. 3 3.:- d ' [.. A-5182 Sheet 3, Rev. 3 ~ 1.: th *:"- A 5182 Sheet 4, Rev.!3 j. ,Sq p;- Ae5182 $heet 5, Re.v. 3 14 9 i%, 1..e.: b..k. .. n.. .m.s. HUSCb and TES personnel have cEnitoreil the instalhtion of thoNodif. ications 'ta the suject anchor and.the: above Drawine -and' TES.cnalys's i i reflect as-built conditions. The following factors of .fety e;(1,st fdr thej n ': concrete expansion anchors in the codified-design. .26 f: We c w .v u. Factgl of Saf$h[(h.P) 'i 'Cyndition I i.1! 'L 4 .g.. nr. ' 2.. ','.n ::.:. W.c.a;: O .!. 2 - c '. i ? L 2 p n ,.. n. x N. i.., ' ,F l .js 6h .5 . g. The aliniting structural elcr:erition the codif 'ed enthori M die:. l threade rod. The following lists the ratio of allownle AISC (desigfload (F,jj) aplied : load (F) for this 9.r. { gg,',,l,:j?g }ri; a .v an p* '.< W,:. :..:..:. l j: .. Condition N ?!! w.,~ - - F .c -. a11F r y[ w'4.q[:r

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S M%~ o TES is continuing to develop loads due to water hmicer and liEPB and I will provide analysis of the anchor for those conditions as soon as they are availabic. Nrcal Technical Reports will be issued to NUSCO as soon as all analyses are coepleted and the reports prepared. If you have any questions, please contact the writer. { Very truly yours, e ? TELEDYNE ENGINEERING SERVICES Donald F. Landers [ Senior Vice President DFL:dm cc: R. D. Ciatto - -P. H. Bangser t i 5 e i I I p. l 1 ( I ~. 1934 181

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,j Loads Used in TES Analysis Hodified Anchor X-10 1 1 1 Load Condition ~~ la 2 F, LB5 +35,450 -129,700 y Vl F, LUS -11,870 1129.200 y f F7. LBS +34,681 1137,100 i M, FT-LBS 1182,537 1563,000 t g i d j M, FT-LB5 1207,018 1478,800 y M. FT-LES 1152,767 _493,700 j [ 7 l 1 i l. }> 4 j {

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Direction of forces provide post conservative load r; car.bination. I i u i i, 4 I 1 I s 2 i s 1 3 1 5 -3 1 a 3 4 j 1 1 a Pj ( 1934 182 l e i ~~ ~ tT g ,7 - - -

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ENGINEERING SERVICES 1 ) w wnu oa a mmm w.ummn ca J a m w u m cngn e ai 3 January 10, 1980 3 3815A-1. b [ 7 .s,. $tr. Eric DeBarba e northeast Utilities Service Cc=pany P.O. Box 270 f Hartford, CT 05101

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Subject:

Damage and Repair of Concrete at Containment Penetration 10A, ,( Gentlesen: V .Toledyne Engineering Services (TES) has inspected concrete cracks around trail baseplates and ceiling baseplate in the vicinity of Hillstone-. Point 1 i containment penetration 10A. The first inspection by TES was made ori i January 3, 1980. It was found that a high loid was imposed on the restraint ? at this location by the 14-inch isolation condenser piping. Tne restraint baseplate transferred this load into the concrete anchorage and this is believed to be the cause of the cracks around the baseplates. Subsequent inspections were made on January 7 and 8, and our recccmendations for

rcpairs were given to NUSCO.

Concreto around the perimeters of the baseplates fastened to the wall was found to be dmaged near the surface. Partial spalling at the corners of the recess has also occurred. Ssall chunks of concrete had spalled en one side of the ceiling. plate and cracking has occurred around the plate perimeter. Also, paint has cracked at the construction joint at the wall penetration. This paint cracking neets the conc ete cracks near the baseplates. Hairline cracks run froc'. the ceiling plcte along the ceiling to the wall. e . Inspection shows no evidence of structural damage to the wall. tioflerhe-chunks of concrete were found to bulge fro 3 the wall. Baseplates remain 'in their original positions. Ultrasonic examination of ^.he anchors showed

deep embedments,18 to 20 inches.

If the high loads had damaged the in-ternal concrete, then permanent deflection of the baseplatos and bulging or spallinD of very large chunks of centrete would have occurred. Surface ~ da:aage near baseplates was caused by clastic elongation of the anchors-and/or tension-cc=pression waves which occurred when th" plates rebounded. Chipping of dmaged and loose concrete revealed only se: Sce cracks which occurred mainly between the interface of grout and base.;cncrete. .0 ' Paint cracking at the construction joint'. reveals no evit ance of sttuctural dtcage to the. wall. There is no evidence of rebar damar associathd with this paint crack. The rebar performed its intended fune tion of resisting tensile loads during the loading event.',,This-is also true for the' hairline cracks in the ceiling. . O. ...,:.n ENGINEEGs.AND U.ETALLUnCl!Tr$ " ~. " " \\~ . 'S,v. q.. y..

"A T9 LTfrht: i r..< 1 -) - .. l ENGJNEER!NGSERVICES, ....i . $ ?,.. / !!!r. Eric OcBerba ~ 9 >-: r January 10, 1980 h' X. s. Page Two ',9 ..' J. .EM q q, G.,.. ..,m, - It is concluded that original anchorage integrity at the basepl.. ate can be restored by removing loose and spalled concrete and replacine this. with a suitable grout such as 5-Star Grout or 5-Star Instant Grout. ;It ' i' is also concluded that the tensile ca;;ccity of cast-in-place and,.expension.. anchors has(not been degraded by thq loading' event,

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