ML20090A235

Statement of Matl Facts as to Which There Is No Genuine Issue Re Allegations Concerning Consideration of Force Distribution in Axial Restraints.Related Correspondence

ML20090A235
Person / Time
Site:	Comanche Peak
Issue date:	07/10/1984
From:	TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:	Atomic Safety and Licensing Board Panel
Shared Package
ML20090A206	List: ML20090A202 ML20090A212 ML20090A222 ML20090A235
References
NUDOCS 8407110311
Download: ML20090A235 (4)

Text

_ - . . -.

(

-~"0u0

~.~ ,

3: ,

E.n "84 Jug 9, 1984 UNITED STATES OF AMERICA r. 2/28  !

NUCLEAR REGULATORY COMMISSION 7 .

'fr. <

r 3 927 /3>!

BEFORE THE ATOMIC SAFETY AND LICENSING BOARN ,

1 In the Matter of )

) Docket Nos. 50-445 and TEXAS UTILITIES ELECTRIC ) 50-446 COMPANY, ET AL. )

) (Application for (Comanche Peak Steam Electric ) Operating Licenses)

Station, Units 1 and 2) )

~

APPLICANTS' STATEMENT OF MATERIAL FACTS AS TO WHICH THERE IS NO GENUINE ISSUE REGARDING ALLEGATIONS CONCERNING CONSIDERATION OF FORCE DISTRIBUTION IN AXIAL RESTRAINTS .

1. Applicants' design approach for modelling trapeze type supports with trunnions is to model the support as a single support acting in the axial direction. (Affidavit at 3.)

P

2. Applicants' modelling technique is r'asonable. e The modelling technique urged by CASE would be very conservative and not necessarily a more realistic modelling technique. ,

l

( Affidavit at 3-4. )  !

3. Applicants evaluated the significance of the effects CASE [

i l alleges should be considered by reanalyzing several piping stress problems utilizing the modelling assumptions CASE l would have Applicants employ. These analyses demonstrated that Applicants' assumption of excluding the rotational restraint of the trapeze support from the analysis has virtually no effect on pipe stresses. (Affidavit at 4-5).

8407110311 840709 PDR ADOCK 05000445 l 0 PDR l

m ""

4 r

4. Applicants' analyses demonstrated that changes in loads on the supports on the reanalyzed stress problems occur only with respect to the trapeze supports themselves. This effect is expected in that modelling the rotational constraint of the support will produce an additional load on L each side of the trapeze which had not been previously i analyzed. These additional loads did not exceed applicable f

allowables. (Affidavit at 5-6.)

5. Applicants evaluated every Unit 1 and common double trunnion I support employed at Comanche Peak for these effects. That analyses demonstrated that the total loads imposed on each side c? the trapeze supports would be acceptable, i.e., in no case were Code allowables exceeded, when the additional loads were factored into the support design. (Affidavit at i

6-8.)

6. With respect to lug-type restraints, it is neither necessary nor reasonabic to expect that the lugs can be installed in a perfect circumferential plane with zero tolerance. The lugs ,

have been installed within reasonable limits. (Affidavit at 10-11.)

7. The stresses which may occur in the pipe, lug or frame as a result of differential engagement of the lugs will be localized. These potential local deformations would be self-limiting and readily redistribute the load to other lugs. Only one other lug need be engaged to fully resist the entire load which may bc imposed. (Affidavit at 10-11.) i i

6 L

8. It is assumed that loads will be transmitted to the lugs furthest from the support anchors, the frame deflection can be larger than initially assumed. However, both frame f deflection and rotation of the pipe will act to close the i

gap to opposite or adjacent lugs. ( Affidavit at 12. )

9. Two conditions may exist with respect to lug-type supports, viz., (1) the lugs may be stronger than the frame (and thus greater frame deflection will result) and (2) the frame may I i

be stronger than the lugs (inducing small deformations in ,

the lug until other lugs are engaged). (Affidavit at 12-13.) [

10. For the case in which the frames are weaker than the lugs, Applicants performed a study of idealized frames loaded axially using the four lug arrangement. These cases t represent the range of deflections which may occur in the i field and, thus, provide evidence of the ability of the frame to deflect to permit engagement of additional lugs.

Only in the second case was it found that a deflection which could (slightly) exceed Applicants' deflection guideline may be required to bring a second lug in contact with the frame.

However, any excess loads would be self-limiti'ng and thus when the load is shared by the second lug the deflection no longer increases for a given load. (Affidavit at 14-15.)

11. To assess the condition in which the frame is stronger than the lug and, thus, lug localized yielding may occur, Applicants analyzed the effect of the maximum localized yielding in the lug and the pipe surface which could occur

6 to bring the additional lugs in contact with the frame.

This analysis was performed using a non-linear finite element technique and the computer program NASTRAN. The result of this analyses show that minimal plastic strains, ,

entirely localized at the surface of the pipe and the welds permit a 1/16" deflection from the lugs with no adverse consequence to the lugs. With respect to the stresses on F the pipe, Applicants' analysis demonstrates that they would also be acceptable. (Affidavit at 15, Attachment 2).  !

, r b

P 4

6 f

- - - - . , - - , ,