ML20234F066
| ML20234F066 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 01/04/1988 |
| From: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| To: | Fairtile M NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20234F069 | List: |
| References | |
| TASK-03-06, TASK-3-6, TASK-RR FYR-88-01, FYR-88-1, NUDOCS 8801110314 | |
| Download: ML20234F066 (2) | |
Text
Telephone (617) 872-8100.
.)
TWX 710-380-7619 YANKEE ATOMIC ELECTRIC COMPANY f,
1671 Worcester Road, Framingham, Massachusetts 01701 January'4, 1988 e
FYR 88 01 4
United States Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 Attention:
Mr. Morton Fairtile q
Project Directorate I-3 Division of Reactor Projects I/II
References:
(a) License No. DPR-3 (Docket No. 50-29)
(b) Letter, YAEC to USNRC (FYR 87-56), dated June 1, 1987 (c) Letter, YAEC to USNRC (FYR 87-67), duted June 30, 1987 (d) Letter, USNRC to YAEC (NYR 87-142), Par. 4.5.2, dated July 16, 1987 i
Subject:
SEP Topic III-6, Reactor Pressure Vessel / Neutron Shield Tank
)
l Seismic Response and ARS Generation l
l
Dear Sir:
During the SEP Topic III-6 review of Yankee Nuclear Power Station (YNPS)-
major mechanical equipment, it was acknowledged that the Reactor Pressure Vessel (RPV) would behave satisfactorily under a Yankee Composite Spectrum (YCS) seismic event. However, a request was made to " demonstrate that the magnitude of any RPV sliding under NRC spectra loading would be within allowable limits."
In References (b) and (c), Yankee committed to demonstrating acceptable RPV response under NRC spectrum loading. Accordingly, at a meeting on December 21, 1987, we presented to the NRC staff the analysis methodologies and results of the RPV seismic evaluation. To address NRC staff concerns expressed at the meeting, we have revised and expanded the enclosed report,
" Summary Evaluation of Reactor Pressure Vessel / Neutron Shield Tank Seismic Response and ARS Generation."
Specifically, the following clarifications are provided in the updated
]
report:
(a) Discussion of Reactor Support Structure (RSS) modeling differences between the RSS models reviewed and approved during SEP (Reference (d)) and the new nonlinear RSS model used to evaluate RPV/NST seismic response.
Specifically, the new RSS model is nearly identical to the previous SEP nonlinear model except for adjustment l
in model vertical stiffness.
l (b) Justification for generating new RSS time-histories and the rationale for using 10% damping.
I c0 l
8801110314 880104 AV lj 1
PDR ADOCK 05000029 l'
P PDR
- I i
i Udited. States Nuclear Regulatory Commission January 4, 1988 1
Attention:
Mr. Morton Fairtile Page 2 FYR 88-01 (c) The cross-correlation coefficient between the horizontal and j
vertical synthetic time-histories.
I (d) The methodology for erlculating friction demand required to negate the potential for RPV/NST sliding.
(e) Discussion of RPV/NST modeling differences between the original (SEP) nonlinear model and the new linear RPV/NST model. Nonlinear gap elements were replaced by rigid spring elements, since the original SEP analysis demonstrated that the gaps did not open.
(f) Concrete bearing pressure at the RSS corbel supporting RPV/NST.
l The attached evaluation conclusively demonstrates that the RPV/NST will neither uplift nor slide under NRC seismic spectra loads.
Based on the favorable results of this analysis, we plan no further action on this matter and are suspending efforts to engineer a plant modification.
i This work fulfills our commitments made in our June 30, 1987 letter, and Item 8 of our June 1, 1987 letter. We have also performed the field inspection mentioned in Par. 4.5.2 of Reference (d). The support configuration conforms to the original design drawings.
As you are aware, Yankee has committed to evaluating large and small bore Safe Shutdown System (SSS) piping and supports inside the containment. We intend to use, in the piping analysis, the new ARS generated from the new synthetic-time histories and revised linear RSS modeling techniques of this RPV analysis.
Yankee believes this letter with the enclosed report provides the necessary information to resolve the subject issue. As discussed at the December 21, 1987 meeting, the staff agreed to issue a safety evaluation within ten (10) working days. from receipt of this letter. Your expedient review is necessary in order for us to maintain our schedule for SSS piping and support evaluations.
Please advise should you require further assistance.
I Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY c[.-o-u,
s I;.Papanic,Jr.
/
Senior Project Engineer Licensing cP/25.325 Attachment ec:
USNRC Region I USNRC Resident Inspector, YNPS 4
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