ML19209C553
| ML19209C553 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 09/27/1979 |
| From: | Rubenstein L Office of Nuclear Reactor Regulation |
| To: | Parris H TENNESSEE VALLEY AUTHORITY |
| References | |
| NUDOCS 7910160131 | |
| Download: ML19209C553 (5) | |
Text
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SEP 2 71979 Docket Nos. : 50-327/328 Mr. H. G. Parris Manager of Power Tennessee Valley Authority 500A Chestnut Street Tower II Chattanooga, Tennessee 37401
Dear Mr. Parris:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION ON SEQUOYAH Enclosed are requests for additional information on containment pressures for Sequoyah. To keep on schedule, we need adequate responses by October 12, 1979.
Sincerely,
[!
L. S. Ib nstein, Acting Chief Light Water Reactors Branch No. 4 Division of Project Management
Enclosures:
As stated cc: Sce next page 1147 293' 79toieo / 3 /
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Tennessee Valley Authority ccs:
Herbert S. Sa,nger., Jr. Esq.
N General Counsel x
Tennessee Valley Authority e{,.
400 Commerce Avenue E11833
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Knoxville, Tennessee 37902 N
.. E. G. Beasley Tennessee Valley Authcrity
- s 400 Commerce Avenue W10Cl31 C
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Knoxville, Tennessee 37902 a_q..
Mr. Michael liarding l'0.
Westinghouse Electric Corporation P. O. Box 355 Pittsburgh, Pennsylvania 15230 Mr. David Lambert Tennessee Valley Authccity 400 Chestnut Street Tower II s-Chattanooga, Tennessee 37401 I"
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ENCLOSURE 022.0 CONTAINMENT SYSTEMS BRANCH In a letter dated September 10, 1979, the NRC was informed by Virginia Electric and Power Company that overpressurization.if the containment at North Anna 3 and 4 could occur as a result of a mais steam line break inr.ue containment. This overpressurization resulted when auxiliary feedwater flow was included in the analysis. NRC is currently assessing the generic implications of this letter.
To assist us in determining if a similar circumstance could occur at your facility, you should tak! the following actions.
- 1) Review your original analysis of this event, and provide NRC with the assumptions used during this analysis.
Particular emphasis should be placed on describing how auxiliary feedwater flow (AFF) was accounted for in your original analysis.
(Reference to previously submitted information is acceptable if identified as to page number and date.) Any changes in your design which would impact the conclusions of your original analysis should be discussed. We are particularly concerned with design changes that could lead to an underestimation of the containment pressure following a MSLB inside containment.
- 2) Specifically, provide the following information for the analyses performed to determine the maximum containment r m.ssure for a spectrum of postulated main steam line breaks for various rea;
.r power levels:
a.
Specify the auxiliary feedwater flow rate that was used in your original containment pressurization analyses.
Provide the bysf 4 7 295 for this assumed flow rate.
_2 b.
Provide the auxiliary feedwater rated flow rate, the run out flow rate, and the pump head capacity curve of your current design.
c.
Provide schematic dratrings to show the auxiliary feedwater system arrangement in your current design.
d.
Provide the time span over which it was assumed in your original analysis that AFF was added to the affected steam generator following a MSLB inside containment.
e.
Discuss the design provisions in the auxiliary feedwater system used to terminate the auxiliary feedwater flow to the aftected steam generator.
If operator action is required to perform this function, discuss the information that will be available to the operator to alert him of the need to isolate the auxiliary feedwacer to the affected steam generator, the time when this information would become available, and the time it would take the operator to complete this action.
If termination of auxiliary feedwater flow is dependent on automatic action, describe the basi operation of the auto-isolation system.
Describe the failure modes of the system. Describe any annunciation devices associated with the system.
f.
Provide the single active failure analyses which specifically identifies those safety grade systems and components relied upon to limit the mass and energy release and the containment pressure response.
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Tnta tinsle failure analysis should include, but not necessarily be li..ed to:
partial loss of containment cooling systems and failure of the auxiliary feedwater isolation valve to close.
g.
For the single active failure case which results in the maximum containment atmosphere pressure, provide a chronology of events.
Graphically, show the containment atmosphere pressure as a function of time for at least 30 minutes following the accident.
For this case, assume the auxiliary feedwater flow to the broken loop steam generator to be at the ps:np run out flow (if a run out control system is not part of the current design) for the entire transient if no automatic isolation to auxiliary feedwater is part of the current design.
h.
For the case identified in (g) above, provide the mass and energy release data in tabular form. Discuss and justify the assumptions made regarding the time at which active containment heat removal systems become effective.
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