ML18030A054
| ML18030A054 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 06/16/1981 |
| From: | Curtis N PENNSYLVANIA POWER & LIGHT CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| PLA-847, NUDOCS 8106180295 | |
| Download: ML18030A054 (8) | |
Text
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REGUL4TVRY INFORMATION DISTRIBUTION SYSTEM (RIDS)
ACCESSIOV NBR:8106180295 OOC ~ DATK: 81/06/16 NOTARI7EDi NO DOCKET FACIL:50 387 Susquehanna Steam Electric Stationp Unit 1E Pennsy1va
. 05000387 50 388 Susquehanna Steam Electric Stations Unit 2P Pennsylva 175F AUTH ~ NAME-AUTHOR AFFILIATION CURTIS f >V ~ >> ~
Pennsylvania Power 8 Light Co.
REC IP ~ NAME RECIPIENT AFFILIATION SCH>>ENCERPA, Licensing Branch 2
SUBJECT:
Forwards resoonse to addi auestion fr om Containment Engineer ina Branch re SEA Outstandina Issue-30
'ISTRISIIT ION CODE:
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TWO NORTH NINTH STREET, ALLENTOWN, PA. 18101 PHONEs (215) 770-5151 Il)
NORMAN N. CURTIS Vtce President-Engineering tk Construction-Nuclear
'bless cess June 16, 1981
'It'g (g
~
Jul v~@1~
8 Mr. A. Schwencer s Chief Licensing Branch No.
2 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C.
20555
~"...9s-i tsd'ocket Nos.
50-387 388 SUSQUEHANNA STEAM ELECTRIC STATION SER OUTSTANDING ISSUE //30 ER100450 FILE 841-2 PLA-847
Dear Mr. Schwencer:
Attached is a response to an additional question from the Containment Engineering Branch.
Very truly yours, r,
N.W. Curtis Vice President-Engineering and Constructi on-Nucl ear cc:
R.M. Stark
UESTION:
Explain why a single failure will not disable both the RHR shutdown cooling function and one RHR loop in the suppression pool cooling mode.
RESPONSE
A.single failure can indeed disable the RHR shutdown cooling function and one RHR loop in the suppression pool cooling mode under the following assumptions.
Both units are operating at full power when a complete long-term loss of offsite power (LOOP) occurs.
This leads to main steam. line isolation and reactor scram.
Following the LOOP all four (4) diesel generators should start to supply power to the ESS busses, however, it is assumed that the 'diesel generator OG501C does not start (single failure).
OG501C supplies power to the ESS busses lA203 and 2A203*, to the RHR pumps 1C and 2C*, and to the RHR service water pump 1A.
Loss of OG501C means that the inboard shutdown cooling isolation valves on both units, 1F009 and 2F009*, loose power to their operators, thus disabling the RHR shutdown cooling mode.
Since these valves are located inside the primary containment it is conservatively assumed that they will not be manually reopened.
Onlv the "B" loop and the corresponding RHRSW loop of the RHR system (in both units) would be readily available for suppression pool cooling, using e.g.
RHR pumps 1B and 2D*.
The "A" loop of one unit could be made available by manually operating four (4) valves(close
- F048A, open
- However, a simul-taneous operation of RHR pumps lA and 2A*. is prohibited by electrical interlocks.
Thus one of the units would have only one RHR loop available in the suppression pool cooling mode without the possi-bilitj to swi<ch to,shutdown cooling.
This case has not been considered in the transients submitted as part of Appendix l of the DAR and may be more limiting.
- However, a similar but more conservative case was analyzed as part of a sengitivity study and resulted in a maximum pool temperature of 203 F.
The assumptions for this case are indentical to case 2.a (Appendix I, DAR) except that shutdown cooling is not initiated.
The curves for reactor pressure vs. time and suppression pool temperature vs. time are attached.,
As mentioned above this case is similar, but more conservative than the case under consideration.
The major difference is that reactor water make-up would not be from the feedwater/condensate system but from HPCI (at reactor pressures above approximately 300 psia) and core spray (at reactor pressures below approximately 300 psia),
which both take suction from the condensate storage tank and/or the suppression pool.
Thus, water much colder than feedwater would be used for make-up.
An asterisk indicates a Unit 2 component.
Page 2
This contributes to the reactor depressurisation and leads to less steam being dumped into the suppression pool.
The peak suppression pool temperature for this case will therefore be lower than in the attached analysis case.
To confirm a temperature of less than 203 F we have initiated an 0
additional analysis case and will include this case in the next revision to Appendix X of the SSES DAR.
o 10 10.
HOURS 10'0 10:
o C
C3 O
lD
,,10 10'0 10'INE RI TER SCRBt1 SECONOS Case 2.a without shutdown cooling SUPPRCGSlOt(
POOL TEMP. flHALYGLG NOOUOQQQl CJCRh KLKClklC SLA'fiOll
C)
C)
Q C)
Q C)
C)
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CD CD C)
CG C)
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LD C)
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C4 C)
C) 10 10 r lOUR5 10 10 10 10 10'iME AFTER SCRAM SECONDS Case 2.a without shutdown cooling SUPPHESS1DH PDDL TEMP. ANALYSIS ouaoocNuuN 4HSll CLCCtall: 4tlltjoK