United States Nuclear Regulatory Commission - Protecting People and the Environment

ACCESSION #: 9803160061

Duquesne Light Company   Beaver Valley Power Station

                         P.O. BOX 4

                         Shippingport, PA 15077-0004

SUSHIL C. JAIN                                    (412) 393-5512

Division Vice President                       Fax (412) 643-8069

Nuclear Services

Nuclear Power Division

                                   March 9, 1998


U. S. Nuclear Regulatory Commission

Attention: Document Control Desk

Washington, DC 20555-0001

Subject:  Beaver Valley Power Station, Unit No. 2

          Docket No. 50-412, License No. NPF-73

          10 CFR 21 Evaluation Report (Status Update): Senior Flexonics

          Expansion Joints

     On November 14, 1997, Duquesne Light Company (DLC) provided a 10 CFR

21 interim report to the NRC via letter L-97-059 regarding the subject

Part 21 notification to DLC through Stone & Webster Corporation.  DLC is

providing a status update report of our 10 CFR Part 21 evaluation of the

subject expansion joints utilized at Beaver Valley Power Station Unit 2.

     The Senior Flexonics expansion joints, which are installed in the

Unit 2 service water system, were evaluated for the effects of increased

stiffness due to expansion joint tie rods and determined that the current

applications of the subject expansion joints are acceptable.

     The Stone & Webster notification identified that the original

modeling techniques for Senior Flexonics metal tied expansion joints may

have produced unconservative loading on the expansion joint assembly

itself as well as adjacent equipment (i.e., pumps, heat exchangers,

etc.).  The expansion Joints were computer modeled to accurately account

for the expansion joint stiffness for lateral and torsional movement.

The axial stiffness of the tie-rods, which governs the joint stiffness

was also correctly modeled.  Although the bending stiffness of the joint

incorporated the expansion joint assembly itself, and not the tie-rods, a

review of the displacements under all loading conditions, shows that the

movements are sufficiently low such that additional bending will not be

induced in or across the joints.  The system is well supported and

operates at a low temperature such that piping system displacements are

well controlled and limited.




Beaver Valley Power Station, Unit No. 2

10 CFR 21 Evaluation Report (Status Update):

Senior Flexonics Expansion Joints

Page 2

     The review of the existing calculation, including a review and field

walkdowns of the subject expansion joints which are located on the Unit 2

Service Water System, shows that the expansion joints will perform their

required function and that the system remains within design compliance.


                                   Sushil C. Jain

c:   Mr. D. S. Brinkman, Sr. Project Manager

     Mr. D. M. Kern, Sr. Resident Inspector

     Mr. H. J. Miller, NRC Region I Administrator


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