ML19347C093
| ML19347C093 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 10/15/1980 |
| From: | Heider L YANKEE ATOMIC ELECTRIC CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19347C094 | List: |
| References | |
| TASK-03-06, TASK-03-07.B, TASK-3-6, TASK-RR WYR-80-114, NUDOCS 8010160571 | |
| Download: ML19347C093 (10) | |
Text
. _ _ _ _ _ _ _ _ - - _ - _ _ _ _ _ _ _ _
Telephone 6l7 366-90ll TWK 7ao. 3 90-0 73 9 YANKEE ATOMIC ELECTRIC COMPANY z.2.2.1 WYR 80-114 L di 20 Turnpike Road Westborough, Massachusetts 01581 Yu%'xs>e m
9 October 15, 1980 United States Nuclear Regulatory Commission Washington, D.C.
20555 Attention: Office of Nuclear Reactor Regulation Mr. Darrell G. Eisenhut, Director Division of Licensing
Reference:
(a) License No. DPR-3 (Docket No. 50-29)
(b) YAEC Letter to USNRC cated September 12, 1980, WYR 80-106 (c) USNRC Letter to YAEC dated August 4, 1980 (d) YAEC Letter to USNRC dated May 7, 1980, WYR 80-49 l
Subject:
Seismic Program at Rowe
Dear Sir:
This letter provides additional information on the details of our seismic program, as discussed with you at a meeting in Bethesda on October 9,1980.
We believe that this material, together with Reference (b) provides sufficient justification for continued operation under 10CFR50.54(f).
The intent of our September 12, 1980 letter [ Reference (b)], was to describe the structural and mechanical modifications now being made at the Rowe plant as well as our program for continued seismic evaluation.
The following information is provided for clarification, and to further justify continued operation.
Structural Modifications Underway Seismic evaluations have been conducted for the vapor container, concrete reactor support structure, reactor coolant pressure boundary, and fuel pool building. Each was analyzed for an applied seismic loading of 0.lg and a RG 1.60 spectrum. The results of these analyses indicated no modifications were required for the steel vapor container or the fuel pool building.
- However, modifications to increase the shear and moment capacities of the concrete reactor support structure, as well as upgrade the support of the steam generators are required.
The effect of these modifications will be (1) to increase the seismic capacity of the 8 0101 sos %
p
October 15, 1980 United States Nuclear Ragulatory Commission Page 2 Attention: Office of Nuclcse Rsactor Rsgulation reactor coolant pressure boundary and (2) to reduce the stress on the reactor vessel outlet nozzles by a factor of 5 Low Public Risk _
It The risk to the public from the Yankee plant is relatively low.
The population
'is a very small plant, rated at only 600 MWT.
There are less than 100 people within a density is also very low.
mile of the plant and less than 17,000 within ten miles (1970 Notification or evacuation of persons in close proximity Census).
to the site could, therefore, be accomplished with relative ease if it should ever be necessary.
Seismically Stable Area Figure 1 shows the absence of any seismic activity anywhere near the The attenuation of all recorded earthquakes for over 300 Rowe site.
years of record allows a maximum ground acceleration of.029g.
Figure 2 compares this historical data with proposed design values.
Figure 3 shows that the bulk of all recorded earthquakes have occurred over 100 kilometers away from the site.
Figure 4 shows that a peak ground acceleration of 0.lg falls within the NRC criteria for a 1,000 - 10,000 year return period.
Figure 5 is a comparison of various proposed response spectra for use in the seismic evaluation. Note that the Reg. Guide 1.60 is more spectrum for which the structural analyses were performed, conservative than either the NRC median spectrum or the Yankee site specific spectrum.
Inherent Seismic Resistance Plant systems and structures are designed very conservatively, such These that considerable inherent seismic resistance is provided.
Some of these conservatisms are developed in detail in Appendix A.
conservatisms are as follows:
Structures, components, and systems are capable of sustaining o
loads which are beyond those which would bring them to their elastic limit without sustaining damage. This plastic range provides a major conservatism available for seismic resistance.
The' materials supplied to meet specified minimum strengths are o
generally of higher strength. Margins exist between allowable
.and ultimate stresses.'
The redundancy provided by diverse systems at Yankee Rowe o
Since these systems are provides a unique conservatism.
k --- -
~
Octobsr 15, 1980 Unitsd States Nuclear Ragulatory Commission Fage 3 Olfice of Nuclear Reactor Regulation Attention:
anchored differently, they will respond differently to seiscic motion, therefore, the loss of one system does not mean loss of function and thereby provides additional assurance that the plant will safely withstand a seismic event.
Code material strengths nre based upon static load tests.
Since dynamic loads conttin a limited amount of energy and are o
applied at a faster rate, the margin between stress and failure for dynamic loads is greater than that for static loads.
The inalastic behavior of the well engineered concrete and steel structures, components and systems provides for energy o
I absorption not normally counted on in design.
l 4
There are numerous examples of the inherent resistance to A refinery in earthquakes provided in plant systems and components.
l Nicaragua withstood a measured 0 34g in 197c, despite the fact that A power plant in it was not designed specifically for earthq2akes.
Alaska withstood approximately 0.2g in 1964, although it was There are many other examples as well.
i designed to only 0.lg static.
Ongoing Seismic Program As stated in Reference (b), we are presently developing analytical 1
methods and computer models for analysis of critical systems and structures, In approximately one which is not expected to be completed until early 1981.
month we expect to meet with your staff to discuss the seismic response However, as spectra for the Yankee Rowe site for use in the actual analysis.
noted in Reference (b), we are prepared to go forward with our analysis of our critical systems, components, and structures using at least two combinations One of these of ground acceleration and response spectra, if necessary.
could, of course, be selected by NRC.
A schedule is provided in Table 1 which indicates the milestone We are present1v completion dates for our seismic evaluation program.
This document is formulating criteria for our proposed seismic input.
expected to be completed in November, 1980.
l Summary In summary, we believe that continued operation is fully justified because:
the seismic
. Structural modifications are already underway to increase 1.
resistance of the plant.
There is a low public risk from this small (600 MWT) plant located in 2.
a very remote area of low population density.
The site is in an extremely stable area from a seismic standpoint.
3 Plant structures and systems have considerable, inherent seismic 4.
stability.
.---- -..A a.----..-
October 15, 1980 Unitsd States Nuclear Rsgulatory Commission Page 4 Office of Nuclear Reactor Regulation
' Attention:
i t
A comprehensive seismic evaluation program is underway.
5 Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY Al w MA4ad J L. H. Heider Vice President COMMONWEALTH OF MASSACHUSETTS)
)ss COUNTY OF WORCESTER
)
Then personally appeared before me, L. H. Heider, who, being duly sworn, did state that he is a Vice President of Yankee Atomic Electric Company, that he is duly authorized to execute and file the foregoing req therein are _true to the best of his knowledge and belief.
l SAu
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Notary Public Robert H. Groce My Commission Expires September 14, 1984 p,g'
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o-TABLE 1 YANKEE R0WE SEIMSIC EVALUATION PROGRAM f
SCHEDULE l
Milestones Date l_
A.
Proposed Yankee Criteria 11/15/80 l
I B.
Analysis and evaluation of reactor building and 02/01/81 RCPS complete C.
Analysis of other Cat.1 buildings complete 03/01/81 Cfloor spectra, response profiles)
L D.-
Analysis and evaluation of safe shutdown systems 09/01/81 complete (piping, anchorage of mechanical / electrical equipment) l E.
Structural Evaluations of (C) above complete 09/01/81 F.
Analysis and evaluation of ECCS/ES systems complete 12/31/81 (piping, anchorage of mechanical / electrical equipment)
I-I
. _..,