ML17252A682
| ML17252A682 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Quad Cities, 05000000 |
| Issue date: | 05/09/1988 |
| From: | Johnson L COMMONWEALTH EDISON CO. |
| To: | Murley T Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML17252A683 | List: |
| References | |
| 4608K, NUDOCS 8805190186 | |
| Download: ML17252A682 (11) | |
Text
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Common-Ith Edison One First Nat-Plaza, Chicago, Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 - 0767 May 9, 1988 Mr. T.E. Murley Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC.
- 20555
Subject:
Quad Cities Station Units 1 and 2 Dresden Station Units 2 and 3 "Response to NRC Request for Additional Information Pertaining to 10 CFR, 50.62 Anticipated Transient Without Scram (ATWS) Rule" NRC Docket No 50-254 and 265 and 50-237 and 249
Reference:
(a): Letter from JA Zwolinski to D;L. Farrar, dated December 17, 1986.
(b): Letter from IM Johnson to TE Murley, dated September 30, 1987 (c): Letter from T Ross to LD Butterfield, dated February 18, 1988
Dear Mr. Murley:
Reference (a) transmitted a copy of the NRC's Safety Evaluation in support of the BWR OWners Group licensing topical response to the ATWS rule.
The same document requested what Commonwealth Edison (CECo) review its conformance to the 10 CFR 50.62 ATWS Rule at its Quad Cities and Dresden Stations against the NRC Safety Evaluation of the GE owner's Group Topical.
Reference (b) provided our response to this request.
Recently, a Request for Information (RAI) was transmitted tQ CECo via Reference (c).
Attached please find a copy of our response to Reference (c).
An additional question was raised by Mr. T Ross (Quad Cities-Project Manager) which was not included in the February 18, 1988 RA!.
We were asked to provide information pertaining to the ARI, RPT and RTS systems/model numbers.
This information is also being provided at this time.
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- Lastly, Commonwealth Edison intends on submitting Recirc Pump Trip (RPT) Technical Specifications for Dresden & Quad Cities Stations by August 1, 1988.
Please direct any questions regarding this matter to this office.
/gs Enclosures cc:
M.Grotenhuis-NRR T. Ross-NRR NRC Resident Inspectors-Dresden & Quad Cities W/O Attachments
. 46081<'
NOTICE THE ATTACHED FILES ARE OFFICIAL RECORDS OF THE DIVISION OF DOCUMENT CONTROL. THEY HAVE BEEN
- CHARGED TO YOU FOR A LIMITED TIME PERIOD AND MUST BE RETURNED TO THE RECORDS FACILITY BRANCH 016.
PLEASE DO NOT SEND DOCUMENTS CHARGED OUT THROUGH THE MAIL. REMOVAL OF ANY PAGE(S) FROM DOCUMENT FOR REPRODUCTION MUST BE REFERRED TO FILE PERSONNEL.
DEADLINE RETURN DATE s-11//r RECORDS FACILITY BRANCH
SARGENT & LUNDY ENGINEERS CHICAGO REQUEST FOR ADDITIONAL INFORMATION ON ATWS REVIEW RELATED TO ALTERNATE ROD INJECTION (ARI) AND RECIRCULATION PUMP TRIP (RPT) SYSTEMS QUAD CITIES STATION - UNITS 1 & 2 DRESDEN STATION - UNITS 2 & 3 Project No. 7947-00 Page 1 of 4 Your submittal letter indicates the material presented is for Quad Cities Station Units 1 and 2 as well as Dresden Units 2 and 3~ Please provide the following design information as supporting documentation of your method of compliance with 10CFRS0.62 and identify the units which are covered by each submittal item~
1.0 The electrical functional diagrams for the ARI and RPT systems from the sensors to the final actuated devices.
Answer:
The electrical functional diagrams for the A~I and RPT systems from the sensors to the final actuated devices are as follows:
Dresden Units 2 Unit 3 12E-6582A 12E-6582B 12E-6582C 12E-6582D 12E-6582E 12E-6582F 12E-6582G 12E-6582H 12E-7582A 12E-7582B 12E-7582C 12E-7582D 12E-7582E 12E-7582F 12E-7582G 12E-7582H Quad Cities Unit 1 Unit 2 4E-6577 A 4E-6577B 4E-6577C 4E-6577D 4E-6577E 4E-6577F 4E-6577G 4E-6577H 4E-7573A 4E-7573B 4E-7573C 4E-7573D 4E-7573E 4E-7573F 4E-7573G 4E-7573H 1.1 Identify the ARI reset capabilities including the time delay to ensure ARI scram has completed its operation.
Answer:
Once the ARI system at Dresden Units 2 & 3 and Quad Cities Units 1 & 2 is initiated, the solenoid operated valves will be energized to initiate a reactor scram~ The manual and automatic signals to the ARI valves seal-in for 30 seconds to assure that the scram air header adequately depressurizes~ After 30 seconds, if the initiation signal is cleared, the ARI valves will be deenergized~ If the initiation signal is still present (after 30 seconds)~ the ARI valves will remain energized until the signal clears.
SARGENT & LUNDY ENGINEERS CHICAGO Project No. 7947-00 Page 2 of 4 1.2 Describe the manual initiation capabilities and the means provided to protect the system from inadvertent operation.
Answer:
For Dresden Units 2 & 3 and Quad Cities Units 1 & 2, two manual initiation switches are provided in the control room for each division of ARI logic. Failure of automatic initiation cannot prevent manual initiation.
In order to avoid an inadvertent ma~ual trip of the ARI system, the two initiation switches per division must first be armed (i.e., collar must be rotated clockwise or counter clockwise a certain specified amount).
Once armed and then depressed, the switches will activate their trip functions.
The manual initiation switches for Dresden Unit 2 are located in the control room main control board (MCB) panel 902-5, both divisions.
Unit 3 is located on MCB panel 903-5, for both of its divisions.
The manual initiation switches for Quad Cities Unit 1 are located in the control room MCB panel 901-5, both divisions.
Unit 2 is located on MCB panel 902-5, for both of its divisions.
The two manual initiation switches are spaced such that only one can be operated at any given time by a single person, this one person would have to operate these manual switches in sequence (i.e., both switches cannot be reached by a single person to operate concurrently).
1.3 Verify no manual bypass of the RPT system is available.
Answer:
To verify that no manual bypass at the RPT system is available, the following schematic diagrams were analyzed:
Quad Ci ti es Dresden Units-1 Unit 2 Unit 2 Unit 3 4E-6577F 4E-7573F 12E-6582F 12E-7582F 4E-6577D 4E-7573D 12E-6582D 12E-7582D 4E-1422 4E-2422 12E-2422 12E-3422 1.4 Identify the ARI/RPT information readouts and indications provided in the control room.
Will the ARI valves have a positive position indication; where will the indication be located.
SARGENT & LUNDY ENGINEERS CHICAGO Answer:
Project No. 7947-00 Page 3 of 4 For Dresden Units 2 & 3 and Quad Cities 1 & 2, the ARI design provides continuous readout of level and pressure~ It also provides logic trip status, power supply status, test status~ and failure status at the ARI panels (located in the auxiliary equipment room).
ARI system annunciators are also provided on a main control board to indicate channel trip, trouble on that the manual pushbuttons are armed~
For Dresden Units 2 & 3 and Quad Cities 1 & 2, the RPT design provides for continuous readout of level and pressure~ It also provides RPT logic trip status~ power supply status, test status, and failure status at RPT panels which are located in the auxiliary equipment room.
Annunciators are also provided on a main control board to indicate channel trip on trouble~
2.0 Provide electrical one-line diagrams to demonstrate the electrical independence between the ARI system and the Reactor Trip System (RTS),
and the capability to perform the ARI function during the loss-of-offsite power event~
Answer:
For Dresden Units 2 & 3 and Quad Cities Units 1 & 2, the ARI design is safety-related and segregated into two electrical divisions; namely Division I and Division II which are maintained separate.
The RTS at the Dresden and Quad Cities stations is the Reactor Protection System (RPS) which is a four-channel electrical arrangement which has individual channel separation.
All four RPS channels are routed in separate conduits and never routed with divisional segregated circuits.
The power for the RTS (i~e., RPS) is 120V ac from the RPS motor generator sets. The ARI system will operate fully from non-interruptible de (i~e~. onsite station batteries) which are independent from the RPS power~ Thus the ARI system will perform its function during any loss of offsite power event.
Note that both the RPS & ARI systems are normally fed from ac sources, where for the ARI system ac is converted to de for power to it. Note, however, that a loss of offsite power the ARI system will be fed from the non-interruptible 125V de battery~ While the RPS will be fed from the diesel generators.
The electrical one-line diagrams that demonstrate the electrical independence between the ARI system and the reactor protection system are attached to the end of this document.
3.0 Describe the system design which permits maintenance and the test of the system logic while the plant is in power operation.
I SARGENT & LUNDY E N G I N E E R 5 CHICAGO Answer:
Project No~ 7947-00 Page 4 of 4 For Dresden Units 2 & 3 and Quad Cities 1 & 2, for each actuation parameter (e.g~. low water level) the logic is arranged in a two-out-of-two configuration per division. This allows individual sensors, trip units, etc~. to be tested or calibrated during plant operation without initiating the ARI system. Test pushbuttons and indicating lights are provided for testing the ARI control logic and instrumentation up to but not including the final ARI solenoid valves.
For Dresden Units 2 & 3 and Quad Cities Units 1 & 2, for each actuation parameter (e.g., low water level) the logic is arranged in a two-out-of-two configuration per division. This allows individual sensor, trip units, etc~. to be tested on calibrated during plant operation without initiating a trip of the reactor recirculation pumps~ Test pushbuttons and indicating lights are provided for testing the RPT control logic and instrumentation up to but not including the final actuating devices (trip coils and breakers).
4.0 Verify that the ARI actuation setpoints will not challenge the RPS scram settings; identify the settings and levels to be used.
AN: pjh 3/16/88 Answer:
For Dresden Units 2 & 3 and Quad Cities Units 1 & 2, the ARI trip settings for the reactor pressure is 1228 psig (nominal) and for vessel level is 59 11 below the separation skirt~ The RPS trip settings for reactor pressure is 1060 psig and for vessel level is 1 11 above the separation skirt. Therefore, the automatic setpoints for ARI actuation have been selected such that they will not challenge the RPS scram function.
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