ML17304B112

Responds to Request for Addl Info Re Seismic Adequacy of Nylon Cable Ties Used to Support Electrical Cables in Cable Trays at Plant,Per Insp Repts.Nylon Cable Tie Location Utilized for Mild Environ

ML17304B112
Person / Time
Site:	Palo Verde
Issue date:	04/04/1989
From:	Karner D ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
161-01819-DBK-J, 161-1819-DBK-J, NUDOCS 8904210251
Download: ML17304B112 (24)

Text

~C CELE P,"TED D1S1IBt.'TlON DE}doNSTRON SYSTEM l

W REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

ACCESSION NBR:8904210251 DOC.DATE: 89/04/04 NOTARIZED: NO DOCKET FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH.NAME AUTHOR AFFILIATION KARNER,D.B.

Arizona Nuclear Power Project (formerly Arizona Public Serv RECIP.NAME RECIPIENT AFFILIATION, Document Control Branch (Document Control Desk)

SUBJECT:

Forwards request for addi info re seismic adecpxacy of nylon cable ties used to support electrical cables xn cable trays.

DISTRIBUTION CODE:

IE01D COPIES RECEIVED:LTR ENCL SIZE:

TITLE: General (50 Dkt)-Insp Rept/Notice of Violation R sponse NOTES:Standardized plant.

Standardized plant.

Standardized plant.

05000528 /

05000529 05000530+

RECIPIENT ID CODE/NAME PD5 PD DAVIS,M INTERNAL: ACRS AEOD/DEIIB NRR SHANKMAN,S NRR/DLPQ/PEB 11 NRR/DOEA DIR 11 NRR/DREP/RPB 10 NRR/PMAS/ILRB12 0~I.EBE~IIJ EG FILE 0'2 EXTERNAL: LPDR NSIC NOTES'OPIES LTTR ENCL 1

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1 RECIPIENT ID CODE/NAME CHAN,T DAVIS,M.J.

AEOD DEDRO NRR/DEST DIR NRR/DLPQ/QAB 10 NRR/DREP/EPB 10 NRR/DRIS DIR 9A NUDOCS-ABSTRACT OGC/HDS1 RGN5 FILE 01 NRC PDR COPIES LTTR ENCL 1

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NOrE K) ALL "RIDS" RECIPZERIS:

PLEASE HELP US 'IO REDUCE ATE!

CONrACr mE DOCIMKr CONr!KL DESK, ROOM Pl-37 (EXr. 20079) K) EXZMINATE YOUR MNE PKK DISTRIBVZIGN LISTS FOR DOCUMENIS YOU DON'T NEZD!

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D S

TOTAL NUMBER OF COPIES REQUIRED:

LTTR 28 ENCL 28

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Arizona Nuclear Power Project P 0 BOX 52034

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PHOENIX. ARIZONA850 I2-2034 I

161-01819-DBK/JMO April 4, 1989 Docket Nos. 50-528/50-529/50-530 Document Control Desk U.S. Nuclear Regulatory Commission Mail Station Pl-137 Washington, D'.C.

20555

Reference:

A)

NRC Inspection Report from J.

B. Martin, NRC to E.

E. Van Brunt, Jr.,

APS, dated March 30,

1988,

Subject:

Safety System Functional Inspection (SSFI)

B)

Letter from E. E.

Van Brunt, Jr.,

APS to NRC Document Control'esk 161-01107 dated June 10,, 1988,

Subject:

SSFI Cable Support Evaluation C)

L'etter from T. L. Chan, NRR to D. B. Karner, APS, dated February 7,

1989.

Subject:

Seismic Adequacy of'Nylon Cable Ties at Palo-Verde Nuclear Generating Station

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2, and 3

SSFI Cable Support Evaluation File:

89-056-026; 89-070-026 The Safety System Functional Inspection identified a

concern regarding the seismic adequacy of nylon cable ties which are used to support electrical cables in vertical cable trays at PVNGS.

APS responded to the concern in Reference B

and NRC requested additional information in Reference C.

Attached is the additional information requested,to complete your evaluation of the nylon cable ties.

8504210251 890404 PDR ADOCK 05000528 9

PDC

0 I~

Document Gc:.trol Desk Pago 161-01819-DBK/JNO April 4, 1989 If you have any questions, please contact A. C. Rogers of my staff.

Sincerel D. B. Karner Executive Vice President DBK/bs, CC:

R.

V. Parkhill 3.

B. Hartin G.

V. Knighton L. Cha..

M. 3. Davis T. 3. Polich (all w/a)

0

ATTACHMENT 1 REQUEST FOR ADDITIONAL INFORMATION (1)

Describe the nature of the plastic nylon ties as it relates to the environments expected'hroughout the installation (describing the ambient conditions, i.e.,

maximum and minimum temperatures, humidity, etc.)

on a

long-term 40 year life basis.

At what points or locations in the plant were the temperature estimates made?

What were the maximum elevated temperatures

found, and what long term effects on the nylon ties can be expected from these temperatures?

(2)

Provide the basis for the determination that only 1E3

rads, t'otal integrated does (TID), of radiation exposure will occur on the nylon tie wraps over a

40 year life cycle of the plant.

At what points or at what locations in the plants were these exposures estimated?

(3)

Given the exposure of 5E5 rads (EPRI NP-1558 and NNNP-4172 SP) as the threshold (i.e., initial onset of detectable tie degradation) what property deterioration, e.g., relaxation, loss of tensile strength, or embrittlement can be expected of the plastic ties?

To what extent would such degradation of the properties affect your analysis results?

(4)

What assurance, and on what basis, can be given that in the long-term 40 year life cycle of the plant; (1) the plastic ties will not break under horizontal seismic forces imposed on the ties by the cable bundles, and (2) the terminal connections will not undergo tension due to slippage of cables under the combined effects of cable dead weight, vertical seismic loads and long term degradation of plastic ties?

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ATTACEiENT 2 (Response to YRC Request for Additional Information)

(1)

The n) ion cable tie location utilized was for a mild environment.

The mild environment parameters were selected from the Updated Final Safety Analysis Report (UFSAR),

Table 3E-1, Environmental Designator IV for the vertical cable trays that lead directly into the bottom of the control room cabinets.

These parameters are the design basis parameters, and are as follows (worst case Design Basis Accident):

Temperature

('F) 40 - 104 Relative Humidity (X) 20 90 Radiation (Rads 40 year integrated dose) less than 10 As identified in the Reference B submittal, the strength of this nylon tie was calculated using a temperature of 120'F and 20X relative humidity.

The maximum design bases temperature is lower, by more, than 20X, of that used in the calculation.

The design basis utilizes a

range for relative humidity (20 90X).

The submitted report used a relative humidity of 20X.

Utilizing a worst case relative humidity of 100X, this will reduce the tie strength by half, which will correlate into a safety margin of more than 12 instead of a safety margin of 24 as stated in the submittal (see Attachment 3 letter from URS Consultants dated 1farch 9, 1989).

(2)

The design basis environmental parameter for radiation was selected from the

UFSAR, Table 3E-1, Environmental Designator IV (mild environment).

This table lists a 40-year integrated dose of less than 1E3 for the control building where the cables enter the bottom of the various cabinets.

(3)

EPRI NP-1558 dated September 1980 "A Review of Equipment Aging Theory and Technology" defines threshold damage as the dose where a

change is first noted and 25X damage dose as one which causes 25X change in a reference property.

This EPRI Report table 7-10 lists polyamide (nylon) with a

threshold damage of 8.6E5 rads and 25X damage of 4.7E6 rads.

Comparing these values with that of item 2

above, the redesign basis radiation parameter is a

factor of 860 times less than the threshold damage.

Therefore, property deterioration, e.g.

relaxation, loss of tensile

strength, or embrittlement, will not occur.

(a)

Demand on plastic ties due to the horizontal components of an SSE was calculated by estimating the vector sum of the maximum accelerations in the two orthogonal horizontal directions.

The calculation of the vector sum of the maximum acceleration of the two horizontal directions assumed 0.5g in the y direction (orthogonal to the cable trays) and O.lg in the x direction (parallel to the cable trays).

The resulting equivalent static acceleration of 0.5lg produces a tensile force of 2.05 lb.

on the plastic ties (refer to Reference B).

The manufacturer's

data, as provided in Reference B,

on physical characteristics of various cable tie materials gives

.the tensile strength of a standard tie at 120'F and 100X Relative Humidity as 25 lb, (refer, to 1 above).

This gives a margin of safety of more than 12 taking worst case parameters as follows:

(4'>>

(b)

Design Basis Parameters

~Anal sis Temperature:

Relative Humidity:

Radiation:

104'F maximum 90K maximum Less -than 10 120'F 100% (as evaluated by Attachment 2)

"'Per EPRI NP-1558, the threshold radiation of polyamide (nylon) is 8s6 x 10 and envelopes the design basis limit.

A realistic, but conservative estimate of the maximum vertical displacements of the cable at its point of entry to electrical cabinets is 0.22 inches as evaluated in the transmitted report of Reference B.

This displacement will not cause tension on the terminal connections since the slack in the cables at the terminal connections alone is more than 1.0 inch.

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ATTACHMENT 3 March 9, 1989 t

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VL ~ 0 ) I'a ) Q VC YPN 8 \\

PJ 4UIA a7. AS\\ IQO I IX l C4e k T3 GlÃP cRI~P 5G FOURTH STRE"T

-': (:55) 957.5sco CF(iC"=9 LCt:G sf'"'k

&GE~e>X U'S ">sGAs Mr. John Kolski Arizona 'Nuclear Pover Project 11226 North 23rd Avenue

Phoenix, AZ 85029

Reference:

Seismic Evaluation of Electrical Cables at Palo Verde Nuclear Pover Plant, June 1988

Dear Mr. Kolski:

In reference to our telephone conversation yesterday on the effect of humidity on the tensile strength of cable ties, please find enclosed a copy of the relevant sections of the technical brochure given by Panduit Corp.

The effect of temperature and humidity has been discussed in this brochure, and shovs for nylon ties the tensile strength reduces by 50X if the tie is exposed to 100X relative humidity (RH).

The tensile strength for the tie at 120 F

and 20X RH vas given in the-referenced report as to be 50 lb.

Therefore, at 100Z RH the tensile strength of nylon ties reduces to 25 lb.

Since the maximum seismic demand on the ties vere calculated to be 2.05 lb.,

then the margin of safety for the nylon ties at 100X RH vill be about 12.

If you have any questions, please do not hesitate to call me.

Very truly yours, Said Bolourchi Proj ect Engineer SB: rm Enclosure

ELECTFIICAL PRQQLJCTS GROUP Q z.

Selection of Cable Ties For Use In Various Environments

~PAHOVffCOW'. 1%l SiNMlf Nhrrevrr glocNoIQ la Qeect

~1m'....

ELECTRA'AODLATO GAO~

I Selection of Cable Ties For Use in Various Environments Installed cable ties of various materials have been exposed to different amounts of radiation to determine the maximum acceptable limit. These tests were conducted by Pandult mainly to determine the acceptability for use In various areas of nuclear power plants (accumulated over 40 year life). Ses Table B for radiation resistance

rating, Moisture Many plastics when exposed to high relative humidity absorb water and, as such, the tensile strength of the material can change dramatically, Nylon B/B when exposed to 100% relative humidity willabsorb as much as 8.6% which will reduce tensile strength by 50%

when compared to a dry ae molded. Polypropylene and TEFZEL>> are low water absorbing materials and, as such, the effect of water ls minimal. See Table B for moisture absorption.

Temperature Plastic materials normally undergo property loss during exposure to high temperature due to oxidation. The maximum temperature for successful service depends upon the material used as well as environmental conditions. Initially, plastics become more flexible and weaker when exposed to high temperatures.

After a period of time, oxidation may occur which will-cause embrlttlement, making plastic cable ties more susceptible to failure from Impact and vibration. Low temperature exposure will also make most plastics more brittle during this exposure but little property loss occurs when the material-ls returned to room temperatures.

The minimum continuous use temperature after Installation Is stated ln Table B.

Tensile Strength Most cable ties are selected based on material, length and minimum loop tensile strength. Minimum loop tensile strength was established under Military Specification Mll.8.23190. Each cross section cable tie (Miniature-M, Intermediate-l, Standard 8, Heavy-H and Extra Heavy EH) has a different loop tensile strength when testing per MIL.8-N190.

The cable tie Is first conditioned at 49'C (120'F), 20% relative humidity for 24 hcurs, then the cable tie ls Installed on a split mandrel and the halves of the mandrel. separated at a rate of 1

per minute (Fig. 1). The separating force required to unlock or break the cable tie ls the loop tensile strength. Loop tensile strength ls dependent both on the locking design and the tensile strength (psl) of the material. As an example, the tensile strength of polypropylene is approximately 1/2 to 1/3 of nylon 8/8; thus the loop tensile strength of a given cross section tie made of polypropylene would be much less than a tie made of nylon 8/B. This ls thus another property to be considered when selecting a cable tie, The various representative loop tensile strengths are listed ln Table B.

0

'INtmurr....

Ef ECTPK AL PRODUCTS GRDUP Setectlon of Cable Ties For Use fn Various Envlronmbnts Table B Physical Characterlstlcs af Var(aus Cable T{e Mhterlats Propert/as Tensile Strength 73'F (psl)

Color Ui Flammablllly Radlat/on Realstence I/t/ster Absorptfon (24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />s}

UltravlOlat Light Resistance Max. Conllnuous Tempefs'tufe Mln. Continuous Temperature Types and Sizes ol Ties Available Loop Tensile Mln.

Strength Int.

e 120o F Std.

20% RH Hvy.

EH Tool Installed Pandult Part Mo.

or Su//lx Natural 0/8 Nylon 11,200"l Natural 04V 2 1,x 10'ads 2%

Poor 185'F 40'F 18 lb.

30/40 lb.

50 lb.

120/t 75 lb.

260 Ib, OS28 STB GS4H STH GS4EH 8TEH None Weather ltestatant Nylon 8/8 9 000l'l Slack 94V-2 1 x 10'ads 1.2%

Good 185'F

- 40'F 18 lb.

30/40 lb.

50 lb.

120/1 75 (b.

250 lb.

GBZB BTS 084H STH GS4EH'TEH 4 and 40'eather ttealstant Polypropylene 4 1000I Black Poor 1

x10'ads 0,1%

185'F

- 40'F NIA N/A 30 lb.

60 lb.

QO lb.

GS28

.STB GB4H BTH 084EH STEH

~100 TKFtELa T 500fff Agua 2 x 10'ads

<0.03%

Excellent 302'F

~ - 60'F 18 lb.

NIA 50 lb.

120 lb.

N/A G82B 084H STB STH STEH

~78 8talnteee Steel 00,000l'I Stainless Excellent 2 x 10'la*

Excellent 1000'F

-112iF N/A N/A 100 lb.

250 lb.

MIA 084MT BTMT rf1 ASTM oa7s 774 ff) ASTM Df708 IS) MIMKS

~Vorleo Oo pending on at!i.

Conlsal foolorv fOr applloiolo ~faia

0 il II

1 DTSTRIBUTION Docket File PDR LP.DR PD 5 JLee DOCKET NO(S).

STN 50-528 Mr. Donald B. Karner Executive Vice President Arizona Nuclear Power Prospect Post Office Box '52034 Phoenix, Arizona 85072-2034

SUBJECT:

ARIZONA PUBLIC SERVICE COMPANY~ ET AL PALO VERDE NUCLEAR GENERATING STATION The following documents concerning, our review of the subject facility are transmitted for your information.

Notice of Receipt of Application, dated Draft/Final Environmental Statement dated Notice of Availability of Draft/Final Environmental Statement, dated Safety Evaluation Report, or Supplement No.

dated Environmental Assessment and Finding of No Significant Impact, dated Notice of Consideration of Issuance of Facility Operating License or Amendment to Faci1 ity Operating

License, dated x Hi-Weekly Notice; Applications and Amendments to Operating Licenses Involving No d d, d~d 1'1l Exemption, dated Construction Permit No.

CPPR-

, Amendment No.

dated Facility Operating License No..

, Amendment No.

dated Order Extending Construction Completion Date, dated Monthly Operating Report for transmitted by letter dated Annual/Semi-Annual Report-transmitted by letter dated

Enclosures:

As stated Office of Nuclear Reactor Regulation cc:

See next page 0$ SIC E/

SURNAME/

0AVCP P/PD5 C FORM 318110IBOI NRCM 0240 4

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OFFlCIAL RECORD COPY

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Mr. Donald B. Karner

. Arizona Nuclear Power Project Executive Vice President Post. Office Box 52034 Phoenix, Arizona 85072-2034 Palo Verde cc Arthur C. Gehr, Esq.

Snell 5 Wilmer 3100 Valley Center

.Phoenix, Arizona 85073 Charles R. Kocher, Esq. Assistant Council James A. Boeletto, Esq.

Southern California Edison.Company P. 0.

Box 800

Rosemead, California 91770 Mr. Tim Polich U.S.,Nuclear Regulatory Commission HC-03 Box 293-NR Buckeye, Arizona 85326 Regional Administrator, Region V

U. S. Nuclear Regulatory Commission 1450 Maria Lane Suite 210 Walnut Creek, California 94596 Mr. Charles B. Brinkman Washington Nuclear Operations Combustion Engineering, Inc.

12300 Twinbrook Parkway, Suite 330 Rockville, Maryland 20852 Mr. Charles Tedford, Director A rizona Radiation Regulatory Agency 4814 South 40 Street Phoenix, Arizona 85040 Chairman Maricopa County Board of Supervisors 111 South Third Avenue Phoenix, Arizona 85003

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