ML20055G767

Ack Receipt of in Response to 900705 Telcon Re Acceptability of THERMO-LAG Fire Barrier Matl.Correspondence Reviewed & Matter Closed

ML20055G767
Person / Time
Site:	Comanche Peak
Issue date:	07/20/1990
From:	Collins S NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:	William Cahill TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
References
NUDOCS 9007240153
Download: ML20055G767 (3)

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..JUL 2 01990s

-M-C In Reply Refer To:

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- TU Electric

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' iATTN:, W. J. - Cahill..-Jr.', Execut_ive-

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. DallaspTexas-75201' Gentlemen:

. Thank you tfor your:1etter of July-13,1990 in response to our July 5, 1990

- telephonerequestregarding-theacceptabi1ItyofTHERMO-LAGfirebarrier' material, which isTinstalled at Comanche Peak Steam Electric Station (CPSES),

- Unit 1.

In your letter you concluded that current receipt inspection-acceptance. criteria, although modified from the original acceptance criteria,-continues to ensure that THERMO-LAG =is acceptable as installed. Your conclusion is based, in part,

.on letters from the vendor,. Thermal Science, Inc. (TSI), to TU Electric, dated November 21 and 22,,1989, which certify that THERM 0-LAG, as installed, is an.

edequate one hour fire barrier at CPSES Unit 1.

We.have reviewed the referenced correspondence and have no further questions at this time.

Sincerely' 7v Original Signed By:

Samuel J. Collins Samuel J. Collins, Director Division-of Reactor Projects CC:

TU Electric ATTH:. Roger D. Walker, Manager, Nuclear Licensing Skyway Tower 400 North Olive Street.: L.B. 81 Dallas.. Texas 75201 Juanita Ellis~

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Log # TXX-90255 1

2 File # 909.5-Ref. # 10CFR50.48 NELECTRIC July 13, 1990 U. S. Nuclear Regulatory Commission Attn:

Document Control Desk Washington, D.C.

20555

SUBJECT:

COMANCHEPEAKSTEAMELECTRICSTATION(CPSES)

DOCKET No. 50-445 THERMO-UG PREFABRICATED PANELS Gentlemen:

On Thursday, July 5,1990, in a teleconference with NRC Region-IV personnel and the-Site Resident Inspector, TU Electric committed to provide the bas-for implementation of THERM 0-LAG fire barrier material acceptance criteria as revised in October of 1989. -The criteria were revised and implemented after minor deviations from our original material acceptance criteria were identified.- The following information regarding the revised acceptance criteria is submitted.

To understand the relative sensitivity of THERMO LAG to configuration variations, a review of the behavior of THERM 0-LAG under fire conditions is useful. THERM 0-LAG is a passive barrier system until it is exposed to the heat flux of a fire.

On exposure to the heat flux at the surface of the barrier, the following mechanisms are activated:

An inorganic-salt is contained within an organic binder that contains glass fiber reinforcement.

This salt undergoes sublimation, which occurs at a constant temperature, absorbing heat and leaving behind a char layer through which sublimed gases must transpire.

The sublimed gases encounter a sufficient residence time in the char layer to undergo endothermic decomposition and disassociation before injection into the surface boundary layer.

The mass transfer of the sublimed gases carries heat to the surface -

3 boundary layer.

The charred surface re-radiates heat energy away from the system.

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., J.o.JUL:13 '90 14:93' FROM SITE-LICENSING PAGE.003 l.

TXX-90255 Page 2 of 4

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THERM 0-LAG does not work solely as an insulating material where thickness governs material effectiveness. THERMO. LAG behavior under fire conditions is-

' dependent on the mass (density) THERM 0 LAG are not significant.of the THERM (thicknesp J Uferences in the Material that is compress.eu from normal fabrication thicknesses retains the mass of-sublimation salts equivalent to normal fabricated THERM 0-LAG.

Thermal Science, Inc.'s (TSI) Quality Assurance / Quality Control program requires that each THERM 0-LAG prefabricated panel be subjected, to detailed QC-

-thickness measurements to verify minimum 1/2 inch material thickness: prior to acceptance. -TSI's QC procedures require that the entire surface be visually.

scanned'and a minimum of 18 preselected locations on each panel be measured to verify required panel thickness. Measurements are made with devices which are tested to verify their accuracy.

These tests are performed at a prescribed frequency. Only panels which meet the criteria of the TSI QC procedure are shipped. This panel fabrication and inspection methodology has remained essentially uncianged since TSI began production of prefabricated panels in the early 1980s.

TSI randomly selected THERMO-LAG prefabricated panels for use in fire tests conducted to qualify the product (including fabrication and inspection-processes) from panels accepted by QC in accordance with TSI's QA program.

Fire tests involving 200 or more randomly selected panels manufactured and-inspected under identical requirements have resulted in no failures of the THERM 0-LAG Fire Barrier System.

The fabrication and inspection methodologies employed by TSI sure a qualified product; however, minor variations in panel thickne s not associated with the specific preselected inspection points may occur.

Such minor variations would have occurred in any of the panels subjected to the fire testing' performed by TSI.

Thus, the fire testing demonstrates that the panels are qualified even with minor variations in the panel thickness.

Subsequent to TU Electric.'s initial supplier qualification audit of TSI's QA Program in 1981, a number' of additional audits and surveillances have been-conducted to verify TSI's continued compliance with procurement documents.

During. late 1989 TU Electric maintained source (shop) inspection at TSI's facilities over extended periods to monitor the performance of TSI's QC inspection efforts and performed inde These~ audits and surveillances have a: pendent inspections of completed panels.

tablished that TSI has satisfactorily splemented the approved QA program requirements.

4,, Jut '13 '90:14: 53 FROM SITE-LICENSING PAGE.004

+4 TXX 90255 Paga 3 of 4-The QC inspections by TSI provide the basis for determining that THERM 0-LAG shipped to CPSES complies with the TSI'and TU Electric acceptance criteria, including acceptance criteria on thickness.

In addition to the QC inspections performed by TSI, CPSES performs receipt inspections.

Minor deviations from TU Electric's QC receipt inspection criteria contained in Specification 2323 MS 38H, Appendix A, regarding minimum thickness of THERM 0 LAG prefabricated panels were identified during receipt of material at CPSES in October 1989.

These deviations were evaluated by TU Electric and TSI.

In many instances of localized thickness reductions, areas of the panels were apparently compressed during handling and or shipment of the material.

In other instances localized thickness reductions apparently resulted from the fabrication-process.

fo address localized areas of thickness reduction of panels supplied to TV Electric-in October 1989, a tolerance for the I/2 inch minimum panel thickness was developed.

TSI provided a quantified tolerance that allowed deviations up to minus 1/8 inch from the 1/2 inch minimum for no more than 2%

of the entire. surface area of the panel.

This tolerance is similar to Underwriters' Laboratories tolerance for sprayed on fire barriers. The basis for reduced panel thickness tolerance included :

1 1)

Localized areas of compressed TH2RM0-LAG material did not represent an actual reduction in the amount of sub11 ming material available for fire response; therefore, initial fire test results were not compromised.

2) Minor localized areas of reduced panel thickness resulting from the fabrication process were not unanticipated.

The random selection of THERMO-LAG panels for fire testing and acceptable fire test results have 1

established that minor thickness variations of this nature do not have an adverse effect on the THERMO-LAG Fire Barrier System and do not compromise initial fire test results.

Based on the above and TSI's responsibility for certification of the product as a one hour fire barrier, the tolerance as defined by TSI was included in TU Electric's receipt inspection criteria.

However, in attempting to implement this criteria it was detemined that the area measurement (e.g., 2%

of surface area -was not practical at receipt inspection.

Therefore, TU Electric rece)ipt inspection criteria based on panel weight were in conjunction with TSI's recommendation.

In addition, TU Electric still requires inspection for damage due to shipping and handling. This does'not change the perfomance criteria required of TSI to provide a one hour fire rated material to TU Electric, nor does it affect TSI's responsibility to inspect and accept THERMO-LAG for the requisite thickness prior to shipment to CPSES.

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JUL;13L'90 14 04 FROM StTE-LICENSING.

PAGE.005' l'. *l

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s TXX 90255' Page 4 of_4

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~ TU Electric's weight measurement in conjunction with-the controls and a

manufacturer's inspections implemented by TSI and the visual: receipt inspections to identify any shipping damage perfomed at receipt of. material provide assurance that the THERM 0-LAG prefabricated panels meet applicable

. fire-test qualification requirements.

4 O

Sincerely,

_y William J. Cahill, Jr..

JDS/ DEN /daj i

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.c - Mr. R. D. Martin, Region IV Resident ~ Inspectors,. CPSES (3)

Mr. J. H. Wilson, NRR u

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