ML20202E146

Forwards Draft RAI Re Application of Leak Before Break for Surge Line Sent 990125.Memo & Encl Does Not Convey Formal RAI or Represent NRC Position

ML20202E146
Person / Time
Site:	Millstone
Issue date:	01/27/1999
From:	Stephen Dembek NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
TAC-MA4126, NUDOCS 9902020267
Download: ML20202E146 (4)

Text

.. ,. - . - _ . _ . . _ - - . - _ . . - . . _ . - - - - . . _ _ . . -

i l , January 27,1999 MEMORANDUM TO: Docket File FROM: Stephen Dembek, Project Manager Project Directorate 1-2 j [  !

l Division of Reactor Projects - 1/Il Office of Nuclear Reactor Regulation l

SUBJECT:

MILLSTONE NUCLEAR POWt:R STATION, UNIT 2, DRAFT REQUEST FOR ADDITIONAL INFORMATION, APPLICATION OF LEAK-BEFORE-BREAK FOR SURGE LINE (TAC NO. MA4126) l The attached request for additional information (RAI) was transmitted by facsimile on January 25,1999, to Ravi Joshi of the licensee's staff. Review of the RAI would allow the t

, licensee to determine and agree upon a schedule to respond to the RAI and/or clarify issues l

that may not need a formal response from the licensee. This memorandum and the attachment do not convey a formal request for information or represent an NRC staff position.

l l Docket No. 50-336 l

Attachment:

As stated l

l DISTRIBUTION l Docket File l PUBLIC Project Director Project Manager f \

! OFFICE PDI-2/PM #. , , 7.-- n p, ,

^"

)y ) j NAME SDembek[M #

/ T-r "

[ .$ 2 lt DATE 1/27/99 OFFICIAL RECORD COPY DOCUMENT NAME: PARAL _ FORM.WPD

! 9902020267 990127 i

PDR ADOCK 05000336 P PDR

lO'cnq

^

4

.% UNITED STATES g g NUCLEAR REGULATORY COMMISSIC/14 2 WASHINGTON, D.C. 20566 4 01

%.....# January 27,1999 MEMORANDUM TO: Docket File

. FROM: Stephen Dembek, Project Manager, Project Directorate 1-2 Division of Reactor Projects - 1/Il Office of Nuclear Reactor Regulation

SUBJECT:

MILLSTONE NUCLEAR POWER STATION, UNIT 2, DRAFT REQUEST FOR ADDITIONAL INFORMATION, APPLICATION OF LEAK-BEFORE-BREAK FOR SURGE LINE (TAC NO. MA4126)

The attached request for additional information (RAI) was transmitted by facsimile on January 25,1999, to Ravi Joshi of the licensee's staff. Review of the RAI would allow the licensee to determine and agree upon a schedule to respond to the RAI and/or clarify issues that may not need a formal response from the licensee. This memorandum and the attachment '

do not convey a formal request for information or represent an NRC staff position.

Docket No. 50-336

Attachment:

As stated b'

i 7

a

a

~

REQUEST FOR ADD!TIONAL INFORMATION MILLSTONE NUCLEAR POWER STATION UNIT 2 REQUEST FOR LBB APPROVAL FOR THE MILLSTONE UNIT 2 SURGE LINE

1. GDC 4 permits the exclusion of dynamic effects associated with postulated pipe ruptures in nuclear power units, from the design basis when analyses reviewed and approved by the Commission demonstrate that the probability of fluid system piping rupture is extremely low under conditions consistent with the design basis for the piping.

In 52 FR 41291, the Commission indicated that the concept of Leak-Before-Break (LBB) is applicable only to high quality piping. The Commission further indicated that LBB is applicable to systems where failure mechanisms such as fatigue are not significant contributors to the potential for pipe rupture. The staff has interpreted the Commission direction to mean that the piping has a low fatigue usage. Given that current fatigue data has shown that the PWR environment can have a significant impact on the fatigue life of stainless steel components (

Reference:

NRC letter to NEl dated September 2,1998, providing Argonne National Laboratory assessment of fatigue data), provide an assessment of the influence of the PWR water environmental effects on the ASME Section 111 fatigue analysis of the surge line.

2. Provide justification why thermal cycling due to turbulent penetration will not affect the fatigue crack propagation calculations of the welds closest to the hot leg (welds 2 through 7 in Figure B-1.)

Appendix A

3. Provide justification for basing Equation 20 in Appendix A on true stress-true strain values of the material. State, or provide a reference, that the stresses and strains in the equations on which the elastic-plastic fracture mechanics analysis in Section 6 and Appendix D is based are true stress true strain quantities, and the analysis uses a true stress-true strain curve.

4. In Appendix A, Equations 19 and 20 are taken from the paper (shown as Reference 19) by Cofie, N. G., et. al., " Stress Strain Parameters in Elastic-Plastic Fracture Mechanics",

presented at the 10th SMIRT International Confstence, August 14-18,1989. This paper was not published in the Proceedings of the Conference. F" ease provide a copy of this paper.

Appendix B

5. The thermal stratification moments used in the fatigue calculations described in CEN-387-P, Rev.1-P-A, were based on maximum stratified flow conJ itions. This was accepted by the staff in its safety evaluation report dated July 14,1993, and included in the report. In Appendix B, the thermal stratification moments are based on a linear top-to-botton. temperature distribution. Provide justification why these moments were determined on this basis, instead of the maximum stratified flow condition, as stated in CEN-387 P, Rev.1-P-A.

1

. _ - . . . _ - - . - . ~ - - - - _ . - _ - - . - . - - - _

2 Section 6.0 and Appendix D

6. Provide the detailed analysis of the maximum throughwall thermal stresses, showing all relevant input parameters for both the temperature and the stress distributions, for the thermal stratification loading condition.

7. The calculation of the global moments and local stresses due to thermal stratification were based on a linear top-to-bottom temperature gradient. In CEOG report CEN-387-P, Rev.1-P-A, dated May 1994, the thermal stratification moments used in the ASME Section lil fatigue calculations were based on maximum stratified flow conditions. This was accepted by the staff in its safety evaluation report dated July 14,1993, and included in the CEOG report. The staff considers maximum stratified flow conditions also applicable to the LBB calculations. Provide a reevaluation of all relevant quantities to the LBB application based on maximum stratified flow conditions.

Section D.5

8. Provide the model for calculating the additional local stresses at the nozzle-to-safe-end welds due to bimetallic stress effects.

9. State the purpose for curve fitting the axial stress distribution with a cubic polynomial.

10. Provide an explanation why the axial stress distribution in Figure D-5 for ferritic steel is apparently the mirror image of the axial stress distribution in Figure D-6 for austenitic steel, both at 550*F.

11. In Figure D-6, the axial stress determined from the curve fit underestimates the axial stress calculated from the stress analysis at the outer surface by about 15%. Provide a discussion of the significance of this underestimation in the fatigue crack growth analysis.