ML17309A211
| ML17309A211 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 12/31/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Maier J ROCHESTER GAS & ELECTRIC CORP. |
| References | |
| TASK-06-07.B, TASK-6-7.B, TASK-RR LSO5-81-12-112, NUDOCS 8201060547 | |
| Download: ML17309A211 (10) | |
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+~*~4 Docket No. 50-244 LS05 12-112 UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O. C 20555 December 31, 1981 Mr. John E. Maier Vice President Electric and Steam PI oduction Rochester Gas 8 Electric Corporation 89 East Avenue Rochester, New York 14649 Dear Mr. Maier
SUBJECT:
SEP TOPIC VI-7.B:
ESF (ENGINEERED SAFETY FEATURES) SWITCHOVER FROM INJECTION TO RECIRCULATION MODE, AUTOIIATIC ECCS REALIGNMENT, GINNA The draft staff safety evaluation report for the systems reviewer of SEP Topic VI-7.8, is enclosed.
We have concluded that the procedures do not allow adequate time for operator action and have suggested methods f'aor improving the procedures.
.You are requested to examine the facts upon which the staff has based-its evaluation and respond either by confirming that the facts are correct, or by identifying any errors.
If in error, please supply corrected information for the doc'ket.
We encourage you to supply for the docket any other material related to this topic that might affect the staff's evaluation This assessment may be revised in the future if your facility design is changed or if the NRC criteria relating to this subject is modified before the integrated assessment is completed.
Your response within 30 days of the date you receive this letter is requested.
If no response is received within that time, we.will assume that you have no comments or corrections.
Enclosure:
As stated cc w/enclosure:
See next page Sincerely, gcd8 8'~~
Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing.
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1 r~ Nr. John E. Maier
'C Harry H. Voigt, Esquire LeBoeuf, Lamb, Leiby and NacRae 1333 New Hampshire Avenue, N. M.
Suite 1100 Mashington, D. C.
20036 Nr. Michael Slade 12 Trailwood Circle Rochester, New York 14618 Ezra Bialik Assistant Attorney General Environmental Protection Bureau New York State Department of Law 2 World Trade Center New York, New York 10047 Resident Inspector R. E. Ginna Plant c/o U. S.
NRC 1503 Lake Road
'. Ontario, New York 14519 Director, Bureau of Nuclear Operations State of New York Energy Office Agency Building 2 Empire State Plaza Albany, New York 12223 Rochester Public Library 115 South Avenue Rochester, New York 14604 Supervisor of the Town of Ontario.
107 Ridge Road West
- Ontario, New York 14519 U. S. Environmental Protection Agency Region 'II Office ATTN:
Pegional Radiation Representative 26 Federal Plaza New York New York 10007 Herbert Grossman Ksq., Chai ra3an
. Atomic Safety an4 Licensing Board U. S. Nuclear RegLIlatory Conadssion Mashington.
D. C.
20555
~4 Dr. Emmeth A. Luebke Atomic Safety and Licensing Board U. S. Nuclear Regulatory Coamission Mashington.
D. C.
20555 Dr. Richard F. Cole Atomic Safety and Licensi'ng Board U-S- Nuclear Regulatory Cotnaissiin":.
Mashington, D. C.
20555
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TOPIC VI-7.B:
ESF ENGINEERED SAFETY FEATURES SWITCHOVER FROM INJECTION TO RECIRCULATION MODE, AUTOMATIC ECCS REALIGNMENT
~C INTRODUCTION Host. Pressurized Water Reactors (PWRs) require operator action 'to realign the ECCS for the recirculation mode follow'ing a LOCA.
The NRC staff has been requiring, on a case-by-case
- basis, some automatic'features to assist in the realignment of the ECCS from the injection to the recirculation mode of operation.
The safety objective of this requirement is to increase-the reliability of long-term cooling by reducing the number of operator actions required to change system realignment to the recirculation mode.
The scope of. this topic requires a review of the ECCS control system and the operator action required to realign the ECCS from injection to re-circulation mode following a LOCA.
The sequence of events from initia-tion of the injection made to completion of the recirculation mode, the systems/components and instrumentation/controls utilized in the injection
'o recirculation process, and the automatic and/or manual process r equir-ed to complete the switchover process are to be reviewed.
%he objective of this review is to deter'mine if automatic switchover is necessary to protect public health and safety.
II.
REVIEW CRITERIA The plant design was reviewed with regard to Appendix A, 10 CFR 50, General. Design Criteria - 35, "Emergency. Core Cooling", which requires that a system to supply abundant emergency core cooling be provided.
RELATED SAFETY TOPICS AND INTERFACES The scope of review for this topic was limited to avoid duplication of effort since some aspects of the review were performed under related topics.
The related topics and the subject matter are identified below.
III-6
. III-10.A III-11 III-12 Iv-l.A V<<10.B V-11
. VI-10.A Seismic Design Considerations Thermal-overload protection for motor operated valves Component Integrity Environmental gualification Operation with less than all reactor coolant loops in service RHR Reliability High Pressure/Low Pressure Interface Testing of ESF System
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IV.
REVIEW GUIDELINES Item 19 of the review procedures in SRP Section 6.3 states that the Complete sequence of ECCS operation from injection te 1ong term core
~ cooling (recirculation) is examined to see that a miaimum of manual action is required and that where manual action is receded, a sufficient
.time (greater than 20 minutes) is available for the aperator to, respond.
further guidance on timing of operator actions is presided by draft ANSI Standard 660.
V.
EVALUATION The first required operator actions in the Ginna emergency procedures follow receipt of the 31$ low RWST level alarm.
The eperator then shuts
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off one ECCS train consisting of one Residual Heat Renoval (RHR) pump, one Containment Spray (CS)
- pump, and at I.east one Safety Injection (SI) pump.
Assuming that the RWST level is initially at the minimum technical specification value and all ECCS pumps operate at maximum capacity, the 315 low RWST level alarm is reached 12.7 minutes foHewing a LOCA.
While this is an exception to the current SRP, historica11y the Reactor Systems Branch has allowed operator actions between 10 and ZQ minutes provided that the actions are simple. (If no action is taken at the 315 low RWST level, the 105 Iow level alarm will annunciate 7.3 minutes later and the RWST will empty 9.8 minutes after the 3IX low level a'larm).
The operator must initiate action by 4.7 minutes after the 315 low level alarm in order to,complete this part of switchover before the 165 low low level alarm rings, assuming I minute per operator action as specified in ANSI N660.
At the 105 low low RWST level alarm, the operator must shut off operating ECCS pumps, align the Pump suction lines to draw from the sump, and re-start the pumps needed for recirculation.
The timing of the pump shutoff sequence is critical since inaction or delayed action could cause the pumps to drain the RWST, cavitate and damage themselves Assuming that one ECCS train of pumps is operating when the,105 Ieve1 aIarm is received, the RWST will be drained in 4;7 minutes without any operator action.
The operator may delay action 1.5 minutes and complete pm'hutoff procedures
- without damage to the pumps assuming one operator action per minute.
Once the pumps are shut off, the concern of draining the BRST and damaging pumps is eliminated, and replaced with a concern tha< valve alignments to the sump must be completed before ECCS flow can be resamed.
The emergency procedures state that the valve re-alignment steps should be completed within 5 minutes so that interruption of core flow wi11 not exceed 5 minutes.
Since a total of 10 actions are needed'to complete switchover (which re-quires 10'minutes assuming one action per minute), this part of the switch-over cannot be assumed to be completed in the allotted time. It should also be noted that tw'o pairs of valves that must be actuated for switchover are 2 minute valves that must'e-operated sequentiaI1y.
This uses up 4 of the 5 minutes allowed for. switchover.. -..
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3 CONCLUSION The current Ginna procedures for switchover from injection do not~et current NRC criteria for operator actions.
The switchover procedures could meet NRC criteria if fewer operator actions were required, and if the timing of operato'r actions was not as critical..The following suggestions are potential methods for an acceptable switchover procedure:
1)
Automatic trio of ECCS pumps on low RMST level; 2)
Start switchover procedure on inactive ECCS train at 31% RMST level to-avoid loss of 'ECCS flow to core during switchover; 3)
Automatic valve realignment following pump shutoff; Other potential solutions will be considered and may be acceptable.
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+o +~*y4 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 OEC t 8 t98t MEMORANDN FOR:
W. Russell, Chief Systematic Evaluation Program Branch, DL FROM:
SUBJECT'.
Mazetis, Acting Chief Reactor Systems
- Branch, DSI REVIEW OF SEP TOPIC VI-7.8 The'Reactor Systems Branch review of SEP Topic VI-7.B, Switchover From Injection to Recirculation, for the RE Ginna Nuclear Power Station has been completed and is contained in the attached enclosure.
We have concluded that the procedures do not allow adequate time for operator action and have suggested methods for improving the procedures.
The Human Factor s Engineering Branch has been included in the distribution list and should be consulted if SEPB wishes to further pursue the area of operator actions.
Please call G. Alberthal of my staff if you need to discuss our findings further.
Enclosure:
As Stated 4
Gerald R.
aze is, Acting Chief Reactor Systems Branch Division of Systems Integration cc:
R.
Snas er E. McKenna E. Marinos
=-
T. Speis R. Mattson B. Sheron W. Hodges V. Moore D. Tondi S. Weiss L
J CONTACT:
G. Alberthal X29407
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ENCLOSURE GINNA SEP TOPIC VI-7.B SWITCHOVER FROM INJECTION TO RECIRCULATION INTRODUCTION Following a Loss of Coolant Accident borated water is injected from the Refuel-ing Water Storage Tank (RWST) into the reactor vessel by the ECCS pumps.
To avoid damage to ECCS pumps and assure abundant cooling water supply to the core, ECCS pump suction must be switched to the containment building sump before the RWST is emptied.
The switchover procedure is examined to evaluate the time available to complete needed operator actions and to -assure that a single failure will not prevent swit'chover.
~ c EVALUATION The R.E.
Ginna procedure for switchover from injection to recirculation requires manual operator action for all.steps.
The evaluation of this procedure is based upon Item 19 of the review procedures in SRP Section 6.3.
This item in the SRP states that the complete sequence of ECCS operation from injection to long term core cooling (recirculation) is examined to see that a minimum of manual action is
- required, and that where manual action is needed, a sufficient time (greater than 20 minutes) is available for the operator to respond.
Further guidance on'timing of operator actions is provided by ANSI standard N660, which is currently in draft form.
The:first required operator actions'in the Ginna emergency procedures follow re-ceipt of the 31% low RWST level alarm.
The operator then shuts off one ECCS train consisting of one Residual Heat Removal (RHR) pump, one Containment Spray (CS)
- pump, and at least one Safety Injection (SI) pump.
Assuming that the RWST level is initially at the minimum technical specification value and all ECCS pumps operate at
maximum capacity, the 31% low RWST level alarm is reached 12.7 minutes following 15 a
LOCA.While is an exception to the current SRP, historically the Reactor Systems Branch has allowed operator actions between 10 and 20 minutes provided that the actions are simple.
(If. no action is taken at the 315 low RWST level, the 10K low low level alarm will annunciate 7.3 minutes later and the RWST will empty 9.8 minutes after the 31Ã low level alarm).
The operator must initiate action by 4.7 minutes after the 31$ low level alarm in order to complete this part of switchover before the 105 low low level alarm rings, assuming 1 minute per operator action as specified in ANSI N660.
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e At the 105 low low RWST level alarm, the operator must shut off operating ECCS pumps, align the pump suction lines to draw from the sump, and restart the pumps needed for recirculation.
The timtng of the pump shutoff sequence is critical since inaction or delayed action could cause the pumps to drain the RWST, cavitate and damage themselves.
Assuming that one ECCS train of pumps is operating when the 105 level alarm is received, the RMST will be drained in 4.7 minutes without any operator action.
The operator may delay action 1.5 minutes and complete pump shutoff procedures without damage to the pumps assuming one operator action per minute.
Once the pumps are shut off, the concern of draining the RWST and damaging pumps is eliminated, and replaced with a concern that valve alignments to the sump must be completed before ECCS flow can be resumed.
The emergency procedures state that the valve re-alignment steps should be completed within 5 minutes so that interruption of core flow will not exceed 5 minutes,.Since'a total of 10 actions are needed to complete switchover (which requires 10 minutes assuming one action per
>>n<<e), this part of tht switchover cannot be assumed to be completed in the allotted time. It should also be 'noted that two pairs of valves that must be actuated for (i
switchover are 2 minute valves that must be operated sequentially.
This uses up 4 of the 5 minutes allowed for switchover.
CONCLUSION The current Ginna procedures for switchover from injection do not'meet current NRC criteria for operator actions.
The switchover procedures could meet NRC criteria if fewer operator actions were required, and if the timing of operator actions was not as critical.
The following suggestions are potential methods for an acceptable switchover procedure:
1)
Automatic trip of ECCS pumps on low RWST level; 2)
Start switchover procedure on inactive ECCS train at 31%
RWST level to avoid loss of ECCS flow to core during switchover; 3)
Automatic valve realignment following pump shutoff; Other potential solutions will be considered and may be acceptable.
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