ML20080A496
| ML20080A496 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 02/01/1984 |
| From: | Tucker H DUKE POWER CO. |
| To: | Adensam E, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.2, TASK-TM NUDOCS 8402060087 | |
| Download: ML20080A496 (10) | |
Text
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o DUKE POWER GOMPANY v.o. nox aamo CHARLOTTE, N.C. 28242
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February 1, 1984 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Ms. E. G. Adensam, Chief Licensing Branch No. 4 Re: Catawba Nuclear Station Docket Nos. 50-413 and 50-414
Dear Mr. Denton:
Section 4.4.3.4 of the Catawba Safety Evaluation Report discusses Open Item 6, Instrumentation for Inadequate Core Cooling Detection. This item was also identified as License Condition 5.
My letter of October 19, 1983 provided additional information on the core exit thennocouples and reactor vessel level instrumentation. TM attached revised Catawba FSAR Table 1.9-1 pages supple-ment the previous description of the core exit thermocouples.
As noted in Table 1.9-1 (Page lic), Incore Thermocouple System Upgrade, the upgrade of the Unit 1 system will be completed by or during the first refueling outage. We have concluded that this implementation schedule is justified as discussed below.
The original design of the Catawba Nuclear Station Incore Thermocouple System was non-safety related. After the TMI-2 accident, it was decided to upgrade this system to Class lE. This upgrade was to be accomplished in two phases.
Phase 1 included the upgrade to Class lE of the in-containment oortion of the system. This involved providing qualified connectors, cabling, and penetrations.
Phase II of the upgrade involves the provision of a safety grade backup display.
Phase 1 of the work was initiated and involved:
1.
Writing specifications, reviewing proposals, and procurement of the equipment necessary for the Phase 1 upgrade.
2.
Reviewing vendor drawings and performing the Duke detailed design necessary for the installation.
3.
Actual installation of the equipment.
This phase has been completed and constitutes the present design as described in FSAR Table 1.9-1.
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Mr. Harold R. Denton, Director February 1, 1984 Page 2 For the Phase II upgrade, rather.than modify the control room displays in isolation, it was proposed that these displays be modified upon completion of the Control Room Design Review and the RB 1.97 Accident Monitoring Instrumentation Review. This assures that all pertinent criteria are properly considered in the final design of the display system and are consistent with the intent of Supplement 1 to NUREG-0737.
In pursuing this objective, Duke has done the following:
1.
Perfomed a Control Room Design Review.
2.
Performed a RG 1.97 Accident Monitoring Instrumentation Review.
3.
Initiated the design engineering necessary to provide the Phase II upgrade.
The use of this orderly approach to the Phase II upgrade will lead to installation during the first refueling outage of Catawba Unit 1.
This schedule provides for the Phase II upgrade to be an integrated part of the installation of changes resulting from the Accident Monitoring Instrumenta-tion Review and the Control Room Design Review.
It is Duke Power Company's conclusion that the implementation date proposed for upgrading of the outside containment portion of the incore themocouple system does not involve any adverse safety considerations. The thermocouple monitoring system as presently installed is a very simple system which, by virtue of its simplicity,is highly reliable and accessible. The design and capabilities of the existing (Phase I upgrade completed) and the upgraded (Phase II) Incore Themocouple System are thoroughly addressed in FSAR Table 1.9-1.
It is important to note that for the existing system, environmental qualifica-tion is provided for the portion of the system which may be exposed to a harsh environment by an event for which the system is required to be operable.
The remaining portions of the system are located in a mild environment.
In that the Phase II upgrade will only provide incremental improvements in the reliability and human factors aspects of existing displays, the proposed implementation date will not result in a reduction in the level of safety.
Very truly yours, Hal B. Tucker ROS/php Attachment
t Mr. Harold R. Denton, Director February 1,1984 Page 3 cc: Mr. James P. O'Reilly, Regional Administrator U. S. Nuclear Regulatory Commission Region II 101 Marietta Street, NW, Suite 2900 Atlanta, Georgia 30303 NRC Resident Inspector Catawba Nuclear Station Mr. Robert Guild, Esq.
Attorney-at-Law P. O. Box 12097 Charleston, South Carolina 29412 4
Palmetto Alliance 21351 Devine Street Columbia, South Carolina 29205 Mr. Jc::se L. Riley Carolina Environmental Study Group 854 Henley Place 4
Charlotte, North Carolina 28207 l
i I
Table 1.9-1 (Page lla)
Response to TMI Concerns
. Incore Thermocouple System I.
Present Design The present incore thermocouple system has 65 T/C's (thermocouples) positioned to sense exit flow temperature of selected fuel assemblies.
The T/C's penetrate the reactor vessel head in 5 locations known as c
instrument ports. Each instrument port has 13 T/C's. Electrical connection to the Class lE T/C's is made at the instrument ports by qualified connectors. The Class lE thermocouples are cabled to quali-fied thermocouple penetrations. Twenty (five per quadrant) Class lE thermocouple channels are provided to insure a minimum of four per core quadrant are always operable. The system design accounts for attrition. The non-safety thermocouples are cabled to reference junction boxes inside containment to allow transition to copper for the remainder of the cabling including the run to an instrument penetra-tion. Outside containment, the class lE T/C's are cabled to reference junction boxes to allow the transition to copper wire. These cables are cabled to the backup display along with the non-safety T/C's.
The backup display will display T/C readings in the control room by l
use of push-to-read switches. All T/C's are cabled from the backup display 'o the primary displays the plant computer.
c A.
Present System Capabilities (NUREG 0737 II.F.2 Attachment 1 format) 1.
Core inlet temperature data is used with core exit temperature to give radial distribution of coolant enthalpy rise across the core.
This is available to the operator via CRT or hard copy in the control room.
l 2.
The plant computer via CRT is the operator's primary display having the following capabilities:
a.
A spatially oriented core map is available on demand indicating temperature and enthalpy rise at each core exit thermocouple location.
b.
The incore thermocouples are an input into the saturation monitor program to assist operator actions for inadequate core cooling procedures.
c.
Direct readout via CRT and hard copy print out capability is provided for all therm] couple temperatures.
This out range extends from 200 degrees F. to 2300 degrees F.
d.
Trending of selected thermocouples to show temperature -
time history is available on demand.
e.
Alarm capabilities are provided thru the saturation monitor program.
Rev. 9
Table 1.9-1 (Page lib)
Response to TMI Concerns f.
Addressed in the Control Room Design Review.
- 3. A backup display is provided in the control room to read any l
of the thermocouples. With push-to-read switches, readings can be taken well within the six minute time guidance. The range of this backup display extends from 200 degrees F. to 2300 degrees F.
- 4. A human factor analysis will be part of the ongoing Control Room Review (See Response to Supplement 1 to NUREG-G737 which was transmitted by letter dated June 1,1983 from H. B. Tucker to H. R. Denton).
- 5. Compliance with Appendix B to Item II.F.2 is addressed by the Incore Thermocouple System upgrade as described below and de-teiled in Section II.A.S.
- 6. The primary and backup displays are electrically independent and are on separate highly reliable power systems.
Isolation devices are not necessary in the present system as the backup display is not in the circuit until a push-to-read switch is used.
- 7. Environmental qualification is provided for the portion of the Incore Thermocouple System which may be exposed to a harsh environment by an event for which the system is required to be operable. This qualification complies with the methodolo-gies as described in FSAR Section 3.11 and the Duke Power Company NUREG 0588 submittal. The remaining portions of the system are located in a mild environment.
The incontainment portion of the Ircore Thermocouple System is seismically qualified to the requirements as defined in FSAR L
Section 3.10.
Seismic qualification of the displays for the existing system is not provided. However in the unlikely event of a seismically induced failure of both existing display systems, T/C readings can be made utilizing portable instrumentation.
- 8. The availability of the present system is expected to be excellent with the plant computer functioning as the primary display. Based on experience at five other Duke nuclear units, l-the display availability is expected to be greater than 99%.
l The backup display is powered independently and further increases p
the overall system availability.
Rev. 9
--~
Table 1.9-1 (Page lic)
Response to TMI Concerns 9.
The provisions of Duke Power Company's Quality Assurance Program as described in FSAR Chapter 17 and Topical Report Duke I were applied to the Class lE incontainment portion of the system.
The remainder of the existing system is non-safety.
II.
Incore Thermocouple System Upgrade The present incore T/C system will be upgraded in the following manner.
From outside of containment the non-safety thermocouple cabling will not be altered. However, the Class 1E T/C cables will be cabled to a Class lE backup display directly from the T/C penetrations. These T/C's will be cabled to the primary display using qualified isolation devices. The backup display will be selected as part of the ongoing control board review.
The upgrade of the incore T/C system will be completed on Unit 1 by or during the first refueling and on Unit 2 prior to fuel load.
A.
Upgraded System Capabilities (NUREG 0737 II.F.2 Attachment 1 forma t)
Display capabilities will be the same as the present design description with exceptions listed below. Exception numbers correspond to original design numbers.
2(f) & 4.
The control room review will be completed and all operator display devices will be human factor designed.
5.
The following consists of an evaluation of the Catawba Nuclear Station Incore Thermocouple System upgrade compliance with Appendix B to Item II.F.2.
Tne para-graph numbers relate directly to Appendix B paragraph numbering.
(1 ) The Class lE instrumentation will be environmentally qualified in accordance with Catawba FSAR Section 3.11 and the Duke Power Company NUREG-0588 submittal. The qualification will apply from the sensor (qualifica-tion assumed per II.F.2 guidance) to the final display device.
For the primary display via the plant computer, qualification applies from the sensor to the isolation device. The isolation device will be accessible for maintenance during accident conditions.
l The Class lE instrumentation will be seismically qualified in accordance with Catawba FSAR Section 3.10.
This instrumentation will operate with the required I
accuracy after, but not necessarily during, a safe d
shut own earthquake.
(
Rev. 9
Table 1.9-1 (Page lid)
Response to TMI Concerns Seismic qualification is not required for the primary display and associated hardware beyond the isolator.
(2) No single failure within the incore thermocouple system or its supporting systems will prevent the operator from being presented with the infor-mation he would need in order to determine the safety status of the station and to bring the reactor to a safe, stable condition following an accident. This is feasible because the incore thermocouple system has two reliable portions:
(a) the non-safety primary display portion which has a battery-backed power source, (b) the re-dundant Class lE portion which has separate battery-backed power sources.
Additional diverse Class lE indications of reactor coolant system pressures and temperatures are provided to assist the operator in the case of discrepancies in redundant read-outs.
Redundant Class lE channels are electrically inde-pendent, energized from separate power supplies, and are physically separated per FSAR Sections 7.1.2.2 and 8.3.1.4 up to and including the isolation device.
Direct recording and trending capabilities are pro-vided for any of the 65 incore thermocouple channels.
(3) The Class lE Incore Thermocouple InstrumentatiJn and backup display will be powered by Class lE power sources.
The primary incore displays are powered by battery-backed power sources.
(4)
Incore instrumentation channel availability will be addressed in the Catawba Technical Specifications.
(5) The provisions of Duke Power Company's Quality Assurance Program as described in FSAR Chapter 17 and Topical Report Duke 1 are to be applied to the Class lE portion of the Incore Thermocouple System.
The primary display and other non-safety hardware beyond the isolation device are not required to be governed by this QA program.
For further information on the Class lE quality assurance provided, please consult the cited references.
Rev. 9
Table 1.9-1 (Page lle)
Response to TMI Concerns (6)
Indication and recording capabilities have been provided as specified in the applicant's response to Supplement 1 to NUREG 0737, Regulatory Guide 1.97 Rev. 2 Section.
(7) 'Same answer as 6.
(8)
Identification of the appropriate post-accident channels is performed as described in the response to Supplement 1 to NUREG 0737, Regula-tory Guide 1.97 Rev. 2 Section.
(9) Qualified isolation devices are being utilized to isolate the Class lE portions of the system from the non-safety portions as specified in RG 1.75.
(10) Test capabilities are provided to check channel operational availability during reactor operation.
(11) Servicing, testing, and calibration programs will be specified to maintain the capabilities of the system.
(12) Means for the removal of channels for maintenance are included in the design, and those means are under administrative control.
(13) The Catawba incore design facilitates the adminis-trative control of the access to setpoint adjustments, calibration adjustments, and test points.
(14) The Catawba design minimizes the existence of conditions which could lead to anomalous indications and confusion of the operator.
t l-(15) The Catawba design facilitates the recognition, location, l
replacement, repair, or adjustment of malfunctioning components or modules.
I L
(16) All incore instrumentation system inputs are from sensors l
which directly measure the desired variables (core exit temperatures).
[
(17) To the extent practical, the same instruments are utilized for accident monitoring as are used for normal operations of the station.
I Rev. 9 l
[
l Table 1.9-1 (Page lif)
Response to TMI Concerns (18)
Periodic testing of the ir. core instrumentation channels will be in accordance with FSAR Table 1.8-1, position on Regulatory Guide 1.118, 6.
The primary and backup display will be energized from inde-pendent battery-backed power sources.
The backup display and associated hardware will be supplied with Class lE power.
Due to physical constraints in the reactor vessel head area configuration, full separation as defined in FSAR Sections 7.1.2.2 and 8.3.1.4 cannot be attained.
The maximum practical separation will be provided in this area and mineral insulated cabling is used to enhance separation and integrity. Once the cabling leaves the refueling canal area separation as specified in FSAR Section 7.1.2.2 and 8.3.1.4 is maintained for the entire remainder of the system cabling.
7.
The Class lE T/C instrumentation (T/C qualification I
assumed) will be seismically and environmentally qualified up to and including the isolation device.
Seismic qualification sill be consistent with the methodologies described in Section 3.10.
Instrumenta-tion subject to a harsh environment will be environmentally qualified consistent with the Duke Power Company position on the Category II Guidelines of NUREG 0588 as detailed in the Duke submittal of June 30, 1982. The isolation device will be in an accessible area following an accident.
8.
The availability of the Class lE back-up displays will be addressed in the Technical Specifications.
9.
The provisions of Duke Power Company's Quality Assurance Program as described in FSAR Chapter 17 and Topical Report Duke 1 are to be applied to the Class lE portion of the Incore Thermocouple System. The primary display and ~other non-safety hardware beyond the isolation device are not required to be governed by this QA program.
For further information on the Class lE quality assurance provided, please consult the cited references.
Procedures See Section 13.5.
II.G EMERGENCY POWER FOR PRESSURIZER EQUIPMENT Rev. 9 l
1 l
Table 1.9-1 (Page 11 )
9 Response to TMI Concerns Pressurizer PORV The pressurizer power-operated relief valves are air-operated with DC control solenoids. Power for the solenoid valves is supplied from the 125VDC Vital Instrumentation and Control Power System (See Section 8.3.2).
The solenoid operators and their controls are safety-related.
Pressurizer PORV Block Valves The pressurizer PORV block valves are motor-operated valves with both motive and control power supplied from the 600VAC Essential Auxiliary Power System (See Section 8.3.1).
The block valves including their power and control circuits are safety-related.
i l
l l
l 1
Rev. 9
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