ML20198D485

Submits Results of Evaluation of Three Design Mods Based on Reviews of Tdi Diesel Generator Owners Group Design Review/ Quality Revalidation Rept.No Design Mods Planned to Lube Oil Sys Areas.Diagram Encl

ML20198D485
Person / Time
Site:	Catawba
Issue date:	05/19/1986
From:	Tucker H DUKE POWER CO.
To:	Harold Denton, Youngblood B Office of Nuclear Reactor Regulation
References
NUDOCS 8605230295
Download: ML20198D485 (5)

Text

• s DUKE Poweit COMPANY P.O. HOX 33180 CHARLO1TE, N.C. 28242 "t"L'""

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May ,19, 1986

r. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission

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Washington, D.C. 20555 Attention: Mr. B. J. Youngblood, Project Director PWR Project Directorate No. 4 ,

Subject:

Catawba Nuclear Station '

Docket Nos. 50-413 and 50-414

Reference:

1. Duke Power Company letter to H. R. Denton, from H. B. Tucker, dated June 21, 1985.

2. " Supporting Calculations for the Evaluation of Comanche Peak Diesel Generator Large Diameter Piping and Supports",

Impell Report No. 02-0630-1230, Rev. O, August, 1984.

Calculation No. CP-EM-001.

3. " Qualification of the Diesel Generator Exhaust Manifold Assembly", Duke Power Company, Calculation No.

CNC-1206.02-50-0001, Rev. O.

4. " Supporting Calculations for the Evaluation of Catawba Generator Skid Mounted Large Diameter Piping and Sup-ports", Impell Report No. 02-0630-1251, Rev. O, September, 1984. Calculation No. CA-EM-001.

5. " Catawba Units 1 & 2 Diesel Generator Piping Qualification, Jacket Water Piping" Duke Power Company, Calculation No. CNC-1206.02-54-0029

6. " Qualification of Jacket Water Dischar ye Piping", 'Impell Report No. 02-0317 Calculation No. CA-JW-001.

7. " Lube Oil Piping Qualification" Impell Report No. 02-0465 Calculation No. CA-LO-003 Rev 0 Dated 10/16/84

8. " Catawba 1 & 2 TDI Lube Oil Qualification", Duke' Power Company, Calculation No. CNC-1206.02-54-0028, Rev, O.

Dear Mr. Denton,

Item 3 of our review (Reference 1) of the "TDI Generator Owner's Group Design Review / Quality Revalidation Report (DR/QR) for the Catawba TDI Diesel Generators" stated that three design modifications proposed by the Owner's Group were being evaluated further by Duke Power Co. The three design l modifications are: the exhaust manifold piping (part no. 02-380A); the jacket

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Page 2, May 19, 1986 CNS, Docket Nos. 50-413 and 50-414 water discharge manifold (part no.02-317 A&B); and lube oil piping (part no. l 02-465A). The results of the Duke Power Co. evaluation are as follows: l Exhaust Manifold Piping, Large Bore, Part No. 02-380A The exhaust manifold piping contains a sliding span of pipe with a slip joint at each end. These slip joints allow movement along the pipe axis.

As stated in the original calculation (Reference 2), this type of component is unstable using the reviewer's linear elastic computer program. Therefore, reference 2 recommended replacing one slip joint at the end of the sliding spans with a welded flange in order to analyze the manifold. The existing exhaust manifold was not shown to be deficient in the original analysis.

Duke Power performed an independent analysis of the exhaust manifold piping (Reference 3). This analysis evaluated the effects of dead weight loads and thermal movements on the sliding span of pipe. In addition, to account for the seismic loading, several bounding cases were evaluated.

These cases were developed using the hard mounted sections of pipe between sliding spans. Each of these sections was analyzed with and without the weight of a sliding span lumped at the end (see Figures 1 and 2).

The results of the Duke analysis indicated that the seismic displacements and rotations at the slip joint are negligable (displacements approximately .1 inches, rotations approximately .015 radians). It is expected that friction from the seals in the slip joints will provide sufficient force (approximately 142 lb.) to move the sliding span along with the adjoining pipe during a seismic event while allowing relative thermal movements. Even if the friction force is inadequate to keep the sliding span mo 'ng with the afjoining pipe sections, restraining devices are provided to prevent separation of exhaust piping. Finally, the gap associated with the slip joint at both normal operating and ambient temperatures is much larger than the total relative movements of the adjacent piping due to thermal motions or seismic events. Therefore, no significant impact between the sliding span and adjacent piping will occur.

Based on this evaluation (Reference 3), the exhaust manifold piping has been found to be acceptable without modification. All stress levels remain well below code allowables. Relative movements at the slip joints are very small and the restraining devices are adequate to prevent any lock up or separation of the exhaust piping. Hence, Duke Power Company plans no design modifications to the exhaust manifold.

Jacket Water Discharge Manifold, Components02-317 A&B Listed below are the DR/QR required modifications to qualify the jacket water discharge manifold, couplings and seals, Component No.02-317 A&B.

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Page 3, May 19, 1986 CNS, Docket Nos. 50-413 and 50-414

1. 2" - 90 dresser elbows (style 90 or 165) are to replace the elbows and flanges on both 2" lines leading from the water jacket shroud i outlet to the 3" line (whicn leads to the 8" discharge header). l

2. Add an anchor just west of the interfacing #1ange between the skid and off skid piping (Component Nos.02-717 and 02-317). The anchor i is to be added as close to the flange as possible and is to be attached'to the engine. l i

3. The first support from cylinder 1 of the 5 inch' diameter water ,

outlet manifold (on both the right and left banks) requires rein-  !

forcement of its members.

4. An 8 inch style 38 dresser coupling with a plain grade 27 gasket is to be added midway between the interfacing flange (between the skid i and on-engine piping) and the 3-inch branch (which leads to the water jacket). This may require relocation of the three tubing taps located in this area.

5. The two supports located on the 8-inch water discharge header (Parts 1 Nos. 02-317-14AD and 02-317-14AC in TDI Parts Manual, Vol . II for Catawba and 101 Dwg. 02-317-14 for Catawba) are to be removed. l To understand the DR/QR recommendations (Reference 6), Duke has performed an analysis of the jacket water discharge piping (Reference 5). From this analysis, it is concluded that thes piping is too stiff;and high thermal stresses exist. The majority of the high stress concentrations occur in the piping connecting the 8" jacket, water header to the 2" turbo charger connection. The proposed DR/QR" modifications for relocation of supports and the use of the flexible couplings allows enough thermal flexibility to meet the code requirements for thermal stresses.

As described in reference 5, another method of creating more thermal flexibility and to qualify the pipe is to reroute the turbocharger jacket water piping to create an expansion loop to absorb the thermal displacements. The piping between the 8" jacket water header and the 2" 1 turbocharger connections is rerouted to provide 4 extra feet laterally for flexibility. Duke Power will reroute the piping rather than use the DR/QR recommended method.

Lube Oil Piping, Large Bore, Part No.'02-465A The DR/QR report on the TDI diesel generators requires Dresser couplings to be installed in the lube oil piping, TDI Component No. 02-465A. Below are the Impel required modifications.

1. A 3-inch style 38 Dresser coupling with a VITON gasket is to be added between the 4""x".3" reducer and the pressure regulator valve on the 3-inch diameter line. The coupling is to be located in the middle of the skewed 2-foot long leg.

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l Page 4, May 19, 1986 i CNS, Docket Nos. 50-413 and 50-414

2. A 5-inch style 38 Dresser coupling with a VITON gasket is to be added midway between the 5" x 3" reducer and the 3-inch diameter branch line (which leads to the pressure regulator valve) on the 5-inch diameter line.

The modifications are added to alleviate thermal stresses. Component No.02-420 (the lube oil pump suction line) also requires the addition of a Dresser coupling. The required coupling is to be installed between the relief  ;

valve branch connection and the pump inlet nozzle.

Impell calculations (Reference 7) for components 02-465A and 02-420 have been reviewed for the possibility of qualifying the components without the

recommended modifications. The results of the Duke Power Co. review 1 (Reference 8) indicate that high thermal stresses due to the growth of the '

engine is the most significant contributor to exceeding the code requirements 1 for expansion stresses. Impell considered the engine growth from the number 8 cylinder to the lube oil pump connections. Review of the engine mounting arrangement indicates that the engine is anchored throughout its length. To 1

still be conservative, engine growth can be taken from the centerline of the

! engine. Reference 8 concludes that the smaller thermal displacement value is enough to qualify the piping in the current condition. Hence, Duke Power plans no design modifications to these areas of the lube oil system.

Very truly yours,

/

4 AK H. B. Tucker HBT:WWG:smk j

xc: NRC Resident Inspector Catawba Nuclear Station

, C. H. Berlinger Office of Nuclear Reactor Regulation U. S. Nuclear Regulator Commission Washington, D.C. 20555 Dr. K. N. Jabbour Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, DC 20555 Dr. J. Nelson Grace Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30323 WWG:05:06:86

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