ML17256B073
| ML17256B073 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 06/25/1982 |
| From: | Maier J ROCHESTER GAS & ELECTRIC CORP. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17256B074 | List: |
| References | |
| TASK-06-07.B, TASK-6-7.B, TASK-RR NUDOCS 8206290188 | |
| Download: ML17256B073 (8) | |
Text
")y" REGULATOR NFORMATION DISTRIBUTION TEM (RIDS)
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A035S COPIES RECEIVED: LTR ENCL SIZE; TITLE: SEP Topics AOCESSION NBR:8206290188 DOC ~ DATE: 82/06/25 NOTARI'ZED!
NO DOCKET FACIL!50-244 Rober t Emmet Ginna Nuclear Plant~
Uni~t 1i Rochester G
05000244
'AUTH BYNAME AUTHOR AFFILIATION MAIERpJ,E
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Rochester Gas 8 Electric Corp.
'RECIP ~ NAME RECIPIENT AFFILIATION ORUTCHFIELD,D~,
Operating Reactor s Branch 5
SUBJECT:
Forwards "Ginna Nuclear "Station ECCS Switchover to recirculation~" in response to NRC 820309 ltr re SEP o
S Sw't hover NOTES:NRR/DL/SEP 1cy.
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~ 89 EAST AVENUE, ROCHESTER, N.Y. 14649 JOHN E. MAIER Vico President TCLCPHONE AREA cooE Vis 546.2700 June 25, 1982 Director of Nuclear Reactor Regulation Attention:
Mr. Dennis M. Crutchfield, Chief Operating Reactors Branch No.
5 U.S. Nuclear Regulatory Commission Washington, D.C.
20555
Subject:
SEP Topic VI-7.B, ESF Switchover R. E. Ginna Nuclear Power Plant Docket No. 50-244
Dear Mr. Crutchfield:
I In response to the NRC's letter dated March 9, 1982 regarding this SEP topic, RG&E contracted with Westinghouse Corporation to evaluate the streamlining of the Ginna ESF Switchover from Injection to Recirculation Mode procedure.
The NRC's concern was primarily that, during the low head recirculation switchover, all ECCS flow to the core would be terminated for some period of time (estimated by RG&E to be approximately 5 minutes).
Westinghouse and RG&E have completed our review of this procedure, and have concluded that some basic revisions would be advantageous.
The conceptual methodology for performing the switchover, and assumptions used to determine the adequacy of this procedure, are provided in Attachment 1.
The Westinghouse analysis is provided in Attachment 2.
RG&E plans to implement this modified procedure in coordination with the NRC TMI Action Plan Item I.C.l, "Short-Term Accident and Procedures Review."
Very truly yours,
'Jo E. Maier Attachments
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Attachment:
Conceptual Methodology for Accomplishing the ESF Switchover from Injection to Recirculation RWST Level minimum will be changed from 230,000 gallons to about 300,000 gallons.
When an RWST low level alarm of 28%
is reached, the operator will shut off one containment spray pump (if more than one is running),
one high head safety injection pump (if more than two are running),
and both residual heat removal pumps.
- Thus, containment. heat removal and atmosphere cleanup will be accomplished by the remaining CS pump, and emergency core 'cool'ing 'by two high head SI pumps Heat balances conducted at the earliest time of RHR pump termination (about 22 minutes) following a large break LOCA show that the flow from one SI pump of (54.51bm/sec) is
- about, 200% of the flow required to keep up with decay and metal heat.
After these pumps are tripped, the operator would close valves 704A and 704B, open valves 850A and 850B, and start the RHR pumps.
At this point there is sufficient water in containment for RHR pump NPSH. If reactor coolant pressure is above the shutoff head of the RHR pumps, ECCS flow would be via"'the SI pumps only. If reactor coolant pressure is below the shutoff head of the RHR pumps, flow would enter the RCS both from the SI and the RHR pumps.
At the RWST low low level alarm of 15%, 'the operator would terminate operation of the remaining SI and CS pumps.
RHR recirculation flow would be maintained.
If the reactor coolant system pressure at this time is greater than the shutoff head of the RHR pumps, flow would not, be available to the RCS.
However, if the event had been a small break LOCA where only the high head safety injection and containment. spray had been used during the 'injection
- phase, the time duration until the low-low level alarm is
'eached would be greater than 75 minutes.
For this case, the reactor vessel and core would be expected to be subcooled and completely filled; substantial time to restore ECCS flow would be available.
In order to initiate high head recirculation, if necessary, valves 896A and 896B, and AOV 897 and AOV 898 would be closed.
Valves 857A,
- 857B, and 857C would be opened, and the Safety Injection pumps would be started.
Valves 896A,
- 896B, 857A,
- 857B, and 857C all have 15 second operators.
AOV's 897 and 898 will close in less than 5 seconds.
The time required for these operations has been calculated.
It is assumed for calculational purposes that each operator manipulation requires one minute.
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Close MOVs 896 A and B
Close AOVs 897 and 898 Open MOVs 857A,
- 857B, and 857C'tart two SI pumps.
Therefore, only four minute's are required to switchover to high head recirculation.
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If no significant time is required for a component to complete its function (e.g.,
a 15 second valve travel time), the movement is included in the one minute.
.Also, if similar components are being manipulated concurrently (e.g., start RHR,pumps lA and 1B),
and the switch locations are proximate, this is considered one manipulation.
Thus, after CS and SI are terminated, each of the following sets of 'actions are assumed to require one minute to perform:
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