ML20128G072
| ML20128G072 | |
| Person / Time | |
|---|---|
| Site: | Hope Creek  |
| Issue date: | 07/02/1985 |
| From: | Mittl R Public Service Enterprise Group |
| To: | Butler W Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8507090030 | |
| Download: ML20128G072 (3) | |
Text
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PS G Company Pubhc Service b
Electnc and Gas 80 Park Plaza, Newark, NJ 07101/ 201430-8217 MAILING ADDRESS / P.O. Box 570, Newark, NJ 07101 Robert L. Mitti General Manager Nuclear Assurance and Regulation July 2, 1985 Director of Nuclear Reactor Regulation U.S.
Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, MD 20814 Attention:
Mr. Walter Butler, Chief Licensing Branch 2 Division of Licensing Gentlemen:
PLANT UNIQUE ANALYSIS REPORT HOPE CREEK GENERATING STATION DOCKET NO. 50-354 Pursuant to our telecon with NRC Containment Systems Branch on May 29, 1985, Public Service Electric and Gas Company hereby submits the following additional information regarding the Hope Creek Generating Station plant unique analysis report hydrodynamic load question responses pre-viously submitted (letter from R.
L.
Mittl, PSE&G to A.
Schwencer, dated 1/31/85):
ITEM 8 How much margin exists for increased torus ring beam sub-merged structure. loads?
Do submerged structure loads occur in controlling load combinations?
RESPONSE
The load combinations which produce controlling stresses are the IBA II and IBA III combinations as shown in PUAR Table 2-2.5-3.
This load combination includes submerged structure loads due to SRV discharge and chugging as shown in PUAR Table 2-2.2-8 and described in Section 2-2.2.1.
The cois-trolling component stresses for these combinations are the ring beam and torus shell local primary membrane stresses and primary plus secondary stress ranges.
The margins for these components range from 13% to 37% as shown in PUAR Table 2-2.5-3.
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Director of 2
7/2/85 Nuclear Reactor Regulation The margins for increased submerged structure loads are obtained by factoring the stress intensitites due to sub-merged structure loads and combining these results with the stress intensities for the remaining IBA loadings such that the ratio of calculated to allowable stress is 1.0.
Doing so shows that the submerged structure loads could increase by as much as 31%.
It is estimated that utilization of SRSS would allow submerged structure load increases of 50% or more.
ITEM 9 What is the basis for ring beam 10% frequency band?
How do Hope Creek ring beam frequencies compare with those of other plants?
RESPONSE
The Hope Creek ring beam frequencies are calculated using the improved Rayleigh method.
In this method the potential energy (or strain energy) is based on the work done by the applied load rather than by integration of the square of derivatives of an assumed shape function as in the displace-ment based method.
Lateral loads are applied to the sub-merged portion of-the ring beam in the suppression chamber analytical model shown in PUAR Figure 2-2.4-1.
The cor-responding displacements are used to calculate the work done.
The potential energy is therefore evaluated quite accurately using this-approach.
The kinetic energy is obtained by computing the summation of w m1 1, where mi is the sum of the nodal ring beam mass and 2
6 2 is the nodal deflection due to the hydrodynamic mass, and 6 1 applied load.
The ring beam frequency is then computed by equating the potential and kinetic energies.
The resulting Rayleigh quotient has second order convergence.
Therefore it is felt that the 10% band for the ring beam frequencies is adequate.
The section modules of the Hope-Creek ring beams and torus shell thickness are generally greater than those of other Mark I plants.
The Hope Creek ring beams have lateral stiffeners at intermediate locations which act to shorten the effective span of the ring beam sections.
The resulting Hope Creek ring beam frequencies therefore are somewhat higher than those of most other Mark I plants as expected.
Director.of 3
7/2/85 Nuclear-Reactor-Regulation should you have any questions in this regard, do not hesi-tate.to contact us.
Very truly yours, in{.
'C D. H. Wagnar.
USNRC Licensing Project Manager
'A. R.
Blough.
.USNRC Senior Resident-Inspector L
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