ML20212R421
| ML20212R421 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 01/23/1987 |
| From: | Whittier G Maine Yankee |
| To: | Thadani A Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM 8340L-GDW, GDW-87-15, MN-87-09, MN-87-9, NUDOCS 8702020643 | |
| Download: ML20212R421 (5) | |
Text
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mamE HARHEE 'AWMICPOWERCOMPARSe
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(207) 623-3521 e
January 23, 1987 MN-87-09 GDH-87-15 Director of Nuclear Reactor Regulation United States Nuclear Regulatory Commission Washington, D. C.
20555 Attention:
Mr. Ashok C. Thadani, Director PHR Project Directorate #8 Division of Licensing
References:
(a) License No. DPR-36 (Docket No. 50-309)
(b) USNRC Letter to HYAPCo dated November 26, 1986
Subject:
Maine Yankee Inadequate Core Cooling Instrumentation System Gentlemen:
Attached is the additional information on Maine Yankee's Inadequate Core Cooling Instrumentation System which was requested by Reference (b). Several of your questions require completion of the detailed design. Assuming that our conceptual design is acceptable to the NRC staff, we propose to provide the additional information following completion of the detailed design.
Please feel free to contact me if you should need any additional information.
Very truly yours, MAINE YANKEE ATOMIC POWER COMPANY
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$m G. D. Whittier, Manager ggg Nuclear Engineering ano Licensing MO OS GDW/bjp bO Enclosure g
OO cc: Dr. Thomas E. Hurley E#
Mr. Pat Sears
@g Mr. Cornelius F. Holden SOo-M 8340L-GDH I
MAIRE YANKEE QTOMIC POWER COMPANY Maine Yankee Response The Maine Yankee SHM system displays temperature margin, but does not display pressure margin.
The Maine Yankee Emergency Operating Procedures utilize temperature margin information but do not require pressure margin information. He do not believe that NRC guidance requires that pressure margin information be available.
Therefore, we believe that the lack of pressure margin information is acceptable.
NRC Ouestion A.5 Is recording or trending of saturation margin provided?
Maine Yankee Resoonse Yes.
Trending of saturation margin is provided by the plant process computer.
NRC Ouestion A.6 Are alarms provided for low saturation margin?
Maine Yankee Resoonse Alarms are provided for low saturation margin on the plant computer and on the safety parameter display system (SPDS), and on a hard-wired annunciator.
NRC Ouestion A.7 Describe: a) means of checking system during operation; b) adequacy of service, test, and calibration procedures; c) administrative control of access to setpoints, calibrations, test points, and removal from service; and d) availability of and training with steam tables and alternative indicators for backup margin calculation.
Maine Yankee Resoonse a.
The subcooled margin monitor reading is compared with hand calculations on a daily basis.
b.
Service test and calibration procedures are currently in effect for the existing subcooled margin monitor system.
These procedures will be reviewed and modified as required once the new system is put in place.
c.
Administrative control of access to setpoints, calibrations, and test points are governed by procedures which are reviewed by the Plant Operation Review Committee and approved by the Plant Manager.
The Maine Yankee tagging system governs removal of the system from service.
d.
Steam tables are available for use in the control room. The use of steam tables is covered in the Operator's Continuing Training Program.
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MAINE YANKEE ATOMIC POWER COMPAPW B.
NRC Ouestion 8.1 An earlier submittal (Maine Yankee letter (MN-83-83) of April 29, 1983) was not clear about appropriate alarm capability on CET temperatures consistent with operator procedure requirements (NUREG-0737, II.F.2, Item 2e). Please describe.
Maine Yankee Response The core exit thermocouples do not have separate alarms, instead the core exit thermocouples provide inputs into the safety parameter display system. The safety parameter display system will provide alarms in the event that a safety parameter has degraded.
The Maine Yankee Safety Parameter Display System is consistent with the Maine Yankee Emergency Operating Procedures.
NRC Ouestion B.2 Earlier submittals preceded the Control Room Design Review with respect to types and locations of displays and alarms determined by human-factors analysis (II.F.2, Att. 1, Item 4a-d).
Please describe the present types and locations of displays and alarms.
Maine Yankee Resco_n_Est The present design for core exit thermocouples has been reviewed by Human Factors engineers as part of the Control Room Design Review.
This program has been reviewed in detail by the NRC staff. Maine Yankee design controls require that any change to the control room receive a Human Factors review. Therefore, a Human Factors review will be included during the detailed design stage for the proposed changes to core exit thermocouples.
NRC Ouestion B.3 One of the CET backup display requirements (II.F.2, Att. 1, Item 3) is to read the 16 thermocouples in no more than six minutes. With the arrangement proposed in the revised submittal, the CET selected for display in a channel also provides the same signal to the subcooling margin and vessel level systems. As a result, the indication of SMM and vessel level will change as different CETs at somewhat different temperatures are selected.
This interaction between the three systems may not be desirable or acceptable in all circumstances. Describe the justification and human-factors considerations for this design feature.
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M AIN E,Y,AN KEE ATOMIC POWER COMPANV '
s Maine Yankee ResDonse The interaction between the subsystems noted in this question ensures that the readings between the two subsystems are consistent.
In order to minimize any negative aspects of this interaction, we plan to stress the selection of the appropriate CET during our Operator Training Program. He believe that this type of system design is preferable to one in which the highest reading CET is automatically selected. The proposed design would allow an operator to select another CET if he determines that one with the high reading has failed. He believe the interaction has the advantage of giving the operator the ability to readily see the affect of temperature changes on the subsystems.
NRC Ouestion B.4 Describe the integration of ICC information, including CET indications, into emergency procedures and training.
Maine Yankee ResDonse ICC information has been integrated into our training program and our Emergency Operating Procedures. The core exit thermocouples and the subcooled margin monitors are used as primary diagnostics in our procedures and training. The primary inventory trend system (PITS) will be used as a backup diagnostic.
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MAINE YANKEE ATOMIC POWER COMPAP$Y ATTACHMENT A A.
Subcooling Margin Monitor (SMM)
NRC Ouestion A.1 Is appropriate Class lE separation provided for the redundant channels?
Maine Yankee Response The redundant channels of the subcooling margin monitor will be separated as required for Class 1E components, except for the core exit thermocouples inside containment.
The core exit thermocouples and associated cabling have already been installed.
These thermocouples were not originally designed to be in separate Class lE channels. However, we believe that this lack of separation is acceptable since separation requirements are primarily established for protection against fire and these core exit thermocouples would primarily be used for evaluating loss of coolant accidents.
NRC Ouestion A.2 Are all components of the SMH system qualified for appropriate degraded environments, including seismic?
Maine Yankee Resoonse All components of the subcooled margin monitor system are qualified for appropriate degraded environments including seismic.
NRC Ouestion A.3 The text of Maine Yankee's submittal states that margin to saturation is displayed while the accompanying table shows the " Operating Range" as T-SAT, 0- 750*F. Does the instrument display saturation temperature or temperature margin to saturation?
If margin is displayed, what range is used? (Reg. Guide 1.97 specifies a range of 200*F subcooling to 35'F superheat).
The range of 0 - 750*F is appropriate for saturation temperature, but not for margin.
Maine Yankee Resoonse The subcooled margin monitor instrument display indicates temperature margin to saturation.
The range of the display is from 50*F superheat to 200*F subcooling. He believe that the instrument display meets the guidance provided in Regulatory Guide 1.97.
NRC Ouestion A 4 t
Can the SMM system display pressure margin as well as temperature margin?
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