ML20043D654

LER 90-007-00:on 881018,during Insp Ice Condenser Basket Found W/Bottom Screws Missing.Caused by Installation Deficiency Because of Improper Matl Selection.Work Request Initiated to Replace Improper screws.W/900530 Ltr

ML20043D654
Person / Time
Site:	McGuire
Issue date:	05/30/1990
From:	Mcconnell T, Sipe A DUKE POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-007, LER-90-7, NUDOCS 9006110031
Download: ML20043D654 (8)

Text

p. 1

^^ :

• F, ,t

?. -^ DukeIbuvr Compaqy (104)8?S 4000

, hlcCuire NucitarStation

' 12700 flagers Ferry Road flantersville, NC28078 8985

- DUKENWER.

MayI 30, 1990 U.S. Nuclear Regulatory Commission' Document-Control Desk Washington, D.C. 20555-

Subject:

McGuire Nuclear' Station, Unit 1 & 2 Docket No. 50-369 Licensee Event Report 369/89-07 Gentlemen:

- Pursuant to 10CFR 50.73 Sections (a)(1) and (d), attached is Licensee Event Report 369/89-07 concerning improper screws that were- installed in the bottom of ice ,

condenser baskets. .This report is being submitted in accordance with 10 CFR i 50.73(a)(2)(1). This event is considered to be of no significance with respect to the health and safety of the public.

i Very truly yours, j

i f/ 'l' 2ft T.L. McConnell ,

DVE/ADJ/cbl/

Attachment xc: Mr. S.D. Ebneter American Nuclear Insurers Administrator, Region II c/o Dottie Sherman, ANI Library i U.S. Nuclear Regulatory Commission The Exchange, Suite 245 101 Marietta St., NW, Suite 2900 270 Farmington Avenue.

Atlanta, GA 30323 Farmington, CT 06032 INPO Records Center Mr. Darl Hood, Project Manager ,

Suite 1500 U.S. Nuclear Regulatory Commission 1100 circle 75 Parkway Office of Nuclear Reactor Regulation Atlanta, GA 30339 Washington, D.C. 20555 M&M Nuclear Consultan'cs Mr. P.K. Van Doorn 1221 Avenue of the Americas NRC Senior Resident Inspector New' York, NY 10020 McGuire Nuclear Station O kD [

n

• .I' '

j Document' Control Deak-4 P. age 2'-

> bxc: B.W.'Bline L.G. Bost.

~J.S. Warren R.L. Gill'

"". . Ch;;; (C;G) - C t. Norfle//

T.D. Curtis (ONS)

P.R.:Herran S.S. Kilborn (W)

M.S. Tuckman

-R.E. Lopez-Ibanez-M.A. Mullen-R.O.-Sharpe.(MNS)'

G.B. Swindlehurst_

K.D. Thomas L.E. Weaver R.L.-Weber J.D. Wylie (PSD)

J.W..Willis (MNS QA)

QA Tech. Services NRC Coordinator (EC 12/55)

MC-815-04 (20) i

~!

I i

.x .

elaC Pere Egg

• U.S. NUCLEM 6 4.utaTORY C08AMitB@et

• APPROVID oess ,so sim0ies

• "m"'**

LICENSEE EVENT REPORT (LER)

,,,,,n, ooCati NUMetR m === m i

,$c,,GuireNuclearStation, Unit 1 oisto;o;ol3l6l 9 i lor l016

"' Improper Screws Were Installed In The Bottom Of* Ice Condenser Baskets-Because of Improper Material Selection SV9edi DAf t 198 Lia NUeSER tel R$ PORT DAf t (76 OTMER f ACILITill INVOLVED 181 1

"* N4 T MMS' MONTM DAY YEAR YEAR bib 4 vw".$ MONTH DAY]YtAR G W" W8 I McGuire, Unit 2 o isto;oioi 3,7,0 90 9 l 0,- 0 l 0l7 Oj q 1l 7 0l0 0l5 3l0 9l 0 o,5,n,o,n, , ,

Tiat REPoR3 is sueuiTr4o PURSUANT To int ataUimtutN,3 o, 30 C,R e <ca.4 e ., ..,. ., caee .~.. . tiii 88004 W 20 402469 30 405tel 90 73aeH2 Hest - 73 71161 30 405teH1 Hit to 3steH11 to 73teH2Het 73 71tel a _

pop 80 40ttelt1Het to 38teH2) 90 72ieH2Hval O Mt see nA cf

, l _ _

X to.73aeH2 Hit 00 73teH2HvedH Al Js54) (

/;q _

30 4esteH1Hdel _

20 405teit1Hivl 90 73aeH2Het to.73teH2HestiHel 20 degliettilles 90.73aelt2 Hie 6 90.73:eH2Het LIClasSEE CONTACT FOR THis LER till qwg TtttPHONE NUMBE R ARE A CODE l Alan Sipe, Chairman, McGuire Safety Review Group 7; Oi 4 8;7, S j i 4i l83i 9 COMPLETE ONE LINE FOR S ACH C0esPONENT F AILURt OtsCRISED IN TMis REPORT (13:

R P sysTIM

• AC R PomfA f C3.USE SYtitM COMPONENT Ma[y'g A C. O NPR S s CAust COMPONENT Ng o pp f I I i i i l l l 1 I i i i I l I I I l  !

l I l I I I I 'l MONTM Dav vEAR

$UPPLEMENTAL REPORf ERPICTED tidi SU8 Mission tit (It ves e.m. tere iM9fCTED $UOMISSION CA TE) eO s

l l l A TR ACT 9L., R, > = =<. , e . e,.,...e., a,,se. e .<e ,,-- .e a.eo o ei On October 18, 1988, during routine inspection, a Unit 1 Ice Condenser Basket was found with the bottom screws missing. At that time, a Problem Investigation Report .

(PIR) was initiated to resolve the problem. Subsequently, work requests were written to inspect and repair all Ice Condenser Baskets in Units 1 and 2. Number 10-16, type 410 stainless steel screws were used for these repairs. Screws were replaced in the bottom or intermediate section of ten baskets in Unit 1 and one basket in Unit 2, On March 30,=1990, during an evaluation being performed by Design Engineering personnel, it was discovered that the original equipment supplier (Westinghouse) had specified specially treated number 10-32, AISI 1022 carbon steel screws for use in the bottom and intermediate sections of the baskets.

A review of the shear and bending forces during seismic and design basis events showed that the number 10-16, type 410 stainless steel screws were unacceptable as used. A PIR was initiated to resolve the problem. All stainless steel screws were replaced in the bottom and intermediate sections of the ten Unit 1 baskets and temporary reinforcing cables were added to support the one Unit 2 basket until the screws can be replaced. This event is' assigned a cause of Installation Deficiency because of improper material selection. Units 1 and 2 have been in all modes of operation during the time the inappropriate screws were installed.

tRCe.. m

..____SYW________._________________.____ _ _ _ _ _ _ _ _ _ _ . _ . - -

U.S. huCLEAR dIuLAtoEY COnansassoons esset Perm ageA *-

" emovto owe no mo-om

. UCENSEE EVENT REPORT (LER) TEXT CONTINUATION EXPints. 41115 PACILity esAatt tal Docust Nuteth QI ggg gyngggg gg, pagg g33 YI'" NaIn UIdain McGuire Nuclear Station, Unit 1 o ls jo jo jo l3l 6l9 9}O __

0l0l7 0l0 0l2 0F 0l6 renv er . =s simisowie s.-.mmamm EVALUATIOh:

Background

The primar) function of the Ice Condenser {EIIS:BC) (NF) system is the absorption of thermal energy released abruptly in the event of a Loss-Of-Coolant Accident (LOCA) for the purpose of limiting the initial peak pressure in Containment. A secondary function of the NF system is the further absorption of energy after the.

initial incident causing the Containment pressure to be reduced to and held at a lower level for a period of time.

The Ice Condenser is subdivided into 24 bays which contain 1944 ice baskets

[EIIStBSKT) that are 12 inches in diameter and 48 feet long. Each bay consists of 9 columns and 9 rows of ice baskets. The ice columns are composed of four basket sections approximately 12 feet long each, filled with borated flake ice.

The baskets are formed ' from a 14 gage ( 075) perforated sheet metal. 'The perforations are 1.0 inch x 1.0 inch holes spaced on a 1.25 inch center. The radius at the junction of the perforation is 0.0625 inch. The ice basket material is made from ASTM-569 which is a commercial quality, low carbon steel. The basket component parts are corrosion protected by a hot dip galvanized process. The perforated basket assembly has an open area of approximately 64 percent to provide tia necessary surface area for heat transfer between the steam / air mixture and the ice to limit the Containment pressure within design limits. Interconnection couplings and stiffening rings are located at the bott.om and at 6 foot levels of each basket section respectively. The bottom coupling and stiffening ring are cylindrical in shape and approximately 3 inches high with a rolled internal lip.

The lip provides stiffening to the basket. These couplings are attached to the ice basket by locking steel metal screws and basket detents.

The basket sections are assembled into the lattice frames to form a continuous column of ice 48 feet high. The bottom wire mesh is designed to allow water to flow out of the basket and has attachments for mechanical connection to the lower support structure to prevent uplift of the ice baskets during a LOCA. The lattice frames provide only lateral ice basket support at intervals corresponding to the stiffened ice basket sections. The vertical loads of the ice and ice basket are transmitted by the basket to the lower support structure. The attachment between the ice basket and the lower support structure is disengaged to permit weighing of the baskets. Provision is made for lifting and weighing the whole length of selected columns for surveillance purposes.

Technical Specification (TS) 3/4.6.5.1 specifies that the ice bed shall be operable cith:

a. The stored ice having a boron concentration of at least 1800 ppm boron as sodium tetraborate and pH of 9.0 to 9.5,

b. Flow channels through the Ice Condenser,

c. A maximum ice bed temperature of less than or equal to 27'F,

,,, e , ,,m .

.u. m m.e-ui =

sRC Peein assa s U S NUCLEAR CBIULiTORY COMMcEB6088

" '. umovio oMe no vu.cim LICENSEE EVENT REPORT (LER) TEXT CONTINUATION t oiRes.nau m

'ACabit f esAut H) '  ! 00CEST 88 UMBER tal gga ,eyesgan (g, Pact (3) h vtan IS8 gEd[,^ 6 c "51e

, p McGuire Nuclear Station, Unit 1 o l5 l0 l0 j o l3 l 6l9 9l0 --

0l 0 l7 --

0l0 ol 3oF 0 l6 rixt ,, . < =ac F a meu nn

d. A total ice weight of at least 2,466,420 pounds at a 95 percent level of confidence, and

e. 1944 ice baskets. .

These conditions are applicable in Mode 1 (Power Operation), Mode 2 (Startup), Mode 3 (Hot Standby), and Mode 4 (Hot Shutdown). The TS action statement states that with the ice bed inoperable, restore the ice bed to operable status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be in-at least Hot Standby within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Cold Shutdown within

~

the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Description of Event During previous Ice Loudenser maintenance, the ice baskets were disassembled at the base to remove foreign material. Because of this practice, it was discovered that some baskets had not been reassembled properly and that attachment pins and screws were missing from the bottom and intermediate couplings. As a result of this discovery, PIR 1-M88-0255 was initiated on October 18, 1988 to address the problem.

The proposed resolution of the problem was to install pins and screws in the bottom

' and intermediate couplings of the baskets which had been found deficient and to 3

perform an inspection of all ice baskets for missing pins or screws, i-Consequently, work requests 501372 and 501948 were generated to inspect all ice baskets to ensure that the bottoms were properly attached and that all necessary screws were installed. During the performance of the repair, McGuire Engineering Support personnel made a decision to replace all missing screws with number 10-16, type 410 stainless steel screws. A previous McGuire Variation Notice had authorized use of the stainless steel screws in one part of the ice b;skets. Since all of the metal screws used in assembly of the ice baskets were originally the same, McGuire Engineering Support personnel involved believed that the stainless steel screws approved by the variation notice were also appropriate for use in any part of the ice basket assembly. Screws were subsequently replaced in the bottom or intermediate sections of ten baskets in Unit 1 and one basket in Unit 2.

On February 19, 1990, during ice unloading operations on Unit 1, Basket 7-8 in Bay 3 was dropped and damaged whi,le attempting to lower it back to the normal position.

Because of this damaged basket, Design Engineering personnel began performing an engineering evaluation of Ice Condenser operability. During the course of this evaluation the Design Engineering personnel involved also received queries from McGuire personnel concerning commercial grade screws for Ice Condenser use.

Because of the questions about commercial grade and the evaluation of Ice Condenser basket structure, Design Engineering personnel discovered the error in the type of screw used in the previous repairs.

A review of the shear and bending forces applied to the basket couplings during seismic and design basis events showed that the number 10-16, type 410 stainless steel screws were unacceptable for use in the bottom or intermediate couplings.

i

'U.8 GPC' 19se.5J 0 38t > 00 0 7-NAC.ORM3004 NSU

a _ :

Isac Pero ageA U 4. souctEaa 5 soukifony consuseseose l

. LICENSEE EVENT REPORT ILER) TEXT CONTINUATION unovto owe No mo-om .

. DMatt. 011/5 FACILITY leAAAE m o0CEET 88Undeln tai tan Nuessan ist Past ta i

"*a " M fik" "%*3

~

l McGuire Nuclear Stat' ion, Unit 1 o l6 l0 l0 lo l3 l 6] 9 9l0 --

0l0]7 --

0'l0 0l4 0F 0l 6 text a.-- e mum .as== mac r.= anamm l

-1

'On April 17, 1990, PIR 1-M90-0107 was initiated to_ resolve the problem. As a l result, all stainless steel screws were replaced in the bottom or intermediate couplings of the baskets in Unit 1 Ice Condenser. Stainless steel reinforcing cables were added to prevent movement of the basket in question in the Unit 2 Ice Condenser until the screws can be replaced.

Conclusion l l

This event is assigned a cause of Installation Deficiency because of improper .

material selection. Self tapping stainless steel screws (number 10-16, type 410 l stainless steel) were used for the ice basket couplings in McGuire Unit 1 and Unit l 2 Ice Condensers. The decision to use the stainless steel screws was based on the fact that a previous McGuire Variation Notice had been initiated to allow the use of number 10-16, type 410 stainless steel screws to hold stiffener rings in baskets replacing damaged rings. No other reference was noted on the Manufacturers Drawing as to the material required for screws for the ice baskets and; therefore, the wrong material was chosen when replacing the missing coupling screws. A review of the Design Report for Ice Condenser baskets showed that the original equipment supplier (Westinghouse) had specified carbon steel screws (number 10-32, AISI 1022 E carbon steel) for the Ice Condenser basket couplings. l The basket assembly drawing (MCM 1201.17-0596 sh. 001) does not show a material specification for these screws. During Design Engineering's most recent review of the damaged basket,'a Westinghouse stress analysis was discovered which indicated that the tensile strength of the 10-32, AISI 1022 carbon steel screws was 140 KSI.

The type 410 stainless steel screws used as replacement fasteners have a tensile strength of 75 KSI.

Based on the additional ~information provided by the Westinghouse stress analysis, a review of the shear and bending forces applied to the banket couplings during seismic and design basis events was performed. The review showed that the'410- -

stainless steel screws were unacceptable. The Ice Condenser was therefore inoperable while the 410 stainless steel screws were instilled.

Work requests 97639 and 503532 were initiated to implement orrective actions. The screws were changed in the bottom or intermediate couplings to the original carbon I

steel screws for the baskets in Unit 1. Stainless steel support cables were added to support the basket in Unit 2 until the screws can be replaced. These actions corrected the problem by preventing the possibility of the ice baskets moving out of the Ice Condenser matrix. Subsequently, Unit 1 and Unit 2 Ice Condensers have been declared operable.

A review of the Operating Experience Program database for the past twenty-four months prior to this event revealed no events involving TS violations because of Installation Deficiencies caused by improper material selection. Therefore, this event is not considered to be recurring.

This event is not Nuclear Plant Reliability Data System (NPRDS) reportable.

i

NJtC FOAM 344A

• U.S. CPGs 19884& Mt 900 h

. 0&I '

i_

!. e. . . 4 li i

1000C Po,2 mea

• U S NUC4 TLC C.E!ULATORY COMueOS40.e ,

Anemovlo ow wo mo-om UCENSEE EVENT REPORT (LER) TEXT CONTINUATION EXPtRES: O'31/3

$ACitify asAmet H3 00CRET Nuestem to LLR teUMSE A 161 #A04 t3l

"^a " b'2 '

57.*JR i McGuire Nuclear Station, Unit 1 o p jo jo lo l3 l 6l9 9l0 _ Oj o l7 0l0 0] 5 or 0l6 rext n . = e.we.w mei-ii.manw Hn There were' no personnel- injuries, radiation overexposures, or uncontrolled releases of radioactive material as a result of this event.

y i

COP.RECTIVE ACTIONS:

l Innediate: None i

Subsequent: 1) Work Request 97639 was initiated to replace all improper screws -

1 in the'of intermediate and bottom couplings of the ice baskets  !

l in Unit 1 Ice Condenser.  !

2) Work Request 503532 was initiated to repair basket 7-6 in bay 10 of Unit 2 Ice Condenser.

3) Mechanical Maintenance p.:rsonnel replaced all stainless steel .

screws in the intermediate and bottom couplings of ice baskets I in the Unit 1 Ice Condenser with the proper type screws.

4) Mechanical Maintenance personnel installed temporary stainless L steel support cables around basket 7-6 in bay 10 of Unit 2 Ice 1 l' Condenser, ti Planned: 1) Mechanical Maintenance personnel will install proper type I screws in the bottom coupling of basket 7-6 in bay 10 of Unit 2 Ice Condenser and the temporary support cables will be removed during the next refueling outage.

1 l 2) Design Engineering personnel will initiate an e,ditorial change I to drawing MCM 1201.17-0596 sh. 001 to specify the special I material required for the screws used in the-Ice Condenser i basket couplings.

i ' SAFETY ANALYSIS:

The safety evaluation of the McGuire Ice Condensers is based on having a required number of ice baskets operable with a sufficient quantity of ice. The presence of the stainless steel screws in the bottom or intermediate coupling of the ice l l

baskets did not result in any degradation of Ice Condenser conditions during. normal j operation. The effect of the inappropriate screws was that during a postulated LOCA plus Seismic Event a loaded ice basket could possibly have moved out of the Ice Condenser matrix. The movement could change the flow of fluid through the Ice Condenser, permit increased bypass of fluid around the Ice Condenser, or prevent the ice in the subject basket or adjacent baskets from contributing to the condensing and cooling of the fluid released during a LOCA. Additionally, movement of a loaded ice basket out of the Ice Condenser structure would represent a missile with possible unanalyzed safety questions. However, while the condition is not analyzed, potential damage to other safety related structures should be minimal.

At no time during the period when the inappropriate screws were installed was the Ice Condenser system challenged. No seismic events occurred and no movement of the

.U.S. GPoi 1996 S N.See ,000 F fetc 80mM 3ssa N- - -_ _ _ n _ ______ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ , _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ __ _

A e . . .

U S NUCLEA2 KEYUL& TORY ComenetEStOss IIRC Pere 3pSA ,

" Aw.ovto owe no sino-e+

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION emans a ave 00CElf NUtIDER (21 4th NutsSSR 441 PAGE L3)

PACILITV meAsst H) viaa " E!.M'. -

fJ *.O McGuire Nuclear Stat' ion, Unit 1

~

o ls10loloj3.] 6l9 9l0 _

0] 0l 7 0l0 0 g6 or 0g6 YEsf7 ff mee assee e opusof, use assunnsnof NIIC hwm W ts (171 subject baskets occurred. Also, during this time period, the Containment Spray

[ Ells:BE] (NS) system, the Safety Injection [EIIS:BQ) (NI) system, and other safeguard systems were available to mitigate possible problems during a LOCA to control containment pressure.

This event did not affeet the health and safety of the public.

. f Nec FOmW 346A

, .,