ML20136B148
| ML20136B148 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/17/1985 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| CON-#485-919 FL-85-6, GL-85-06, GL-85-6, OL, NUDOCS 8511200145 | |
| Download: ML20136B148 (7) | |
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PHILADELPHIA ELECTRIC COMPAN 2301 MARKET STREET P.O. BOX e699 Og PHILADELPHIA PA.19101 N ' [1' C
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. E *'ic"5 % U m October 17, 1985 e$/ j g;. J>
0 Docket Nos. 50-352 50-353 O L-Mr. Harold R.
Denton, Director
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Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, D.C.
20555
SUBJECT:
Compliance with 10 CFR Section 50.62, Anticipated Transients Without Scram (ATWS) Events Limerick Generrating Station, Units 1 and 2
REFERENCE:
(1)
Final ATWS Rule, 10 CFR 50.62, published in the June 26, 1984 Federal Register (2)
Generic Letter 85-06, " Quality Assurance Guidance for ATWS Equipment That is Not Safety-Related", dated April 16, 1985 (3)
" Guidance Regarding System and Equipment Specifications", published in the June 26, 1984 Federal Register
Dear Mr. Denton:
10 CFR Section 50.62(d) requires licensees to submit a proposed schedule to s tisfy the requirements of the final Anticipated Transient Without Scram ( ATWS) risk reduction system as described by paragraphs (c)(1) through (c)(5) within 180 days of issuance of the referenced generic letter.
The information i
provided in this letter is sufficient to satisfy the requirement of section (d).
In order to compensate for this submittal being two days late, we are transmitting this material directly to your project manager by expedited mail.
Limerick Generating Station, Units 1 and 2, meet the i
intent of the design requirements of 10 CFR Section 50.62.
The station design incorporates the Redundant Reactivity Control System (RRCS) in conjunction with selected equipment in the i
Control Rod Drive (CRD), the Reactor Recirculation, and Standby Liquid Control (SLC) systems for ATWS prevention and mitigation.
' 0511200145 851017 PDR ADOCK 05000352 PDR p
1
28-50044570
,Mr. Harold R. Denton-October 17, 1985
_Page 2 Limerick Generating Station, Unit 1, has these systems and equipment designed and installed for ATWS prevention and mitigation; however, Unit 2 requires construction completion to include these design features.
The RRCS contains the incident detection sensors and control logic necessary to detect, and in conjunction with the appropriate equipment in the CRD, Reactor Recirculation, and SLC systems, initiate the appropriate actions to prevent or mitigate s
an ATWS event.
The RRCS and appropriate equipment in the CRD, Reactor Recirculation, and SLC systems required for ATWS prevention and mitigation are designed to function in a reliable manner during the conditions expected for ATWS events.
The RRCS monitors reactor water level and pressure.
If reactor pressure exceeds or. reactor vessel level decreases below the corresponding RRCS setpoints, or if the RRCS is manually actuated, the RRCS initiates the appropriate prevention or mitigation actions.
~If RRCS is actuated on high reactor pressure, Alternate Rod Insertion ( ARI)' and reactor coolant recirculating pump trip are immediately initiated.
Feedwater runback and SLC injection are initiated by RRCS after the appropr_iate time delays have expired if the "APRM not downscale" trip signal is present (i.e.,
if reactor power has not decreased).
Reactor Water Cleanup (RWCU) is isolated when SLC injection is initiated so that RWCU will not reduce the boron concentration.
If RRCS is actuated on low reactor vessel level, ARI is immediately initiated.
Reactor coolant recirculating pump trip is initiated by RRCS after the appropriate time delay has-expired.
SLC injection is initiated by RRCS after the appropriate time delay has expired if the "APRM not downscale" trip. signal is present-(i.e., if' reactor power has not decreased).
RWCU is isolated when SLC injection is initiated so that RWCU will not reduce the boron concentration.
If RRCS is manually actuated, ARI is immediately initiated by RRCS.
SLC injection is initiated by RRCS after the appropriate time delay has expired if the "APRM not downscale" trip signal is present.(i.e., if reactor power has not-decreased).
RWCU is isolated when SLC injection is initiated so that RWCU will not reduce the boron concentration.
RRCS is manually actuated by arming and depressing the RRCS manual initiation switches in the control room.
RRCS can be reset ten minutes after the SLC injection time delay has expired, provided the RRCS actuation signals have cleared and the RRCS reset pushbuttons are manually depressed.
29 0044570 Mr. Harold'R. Denton
' October 17, 19 5 Page 3 The RRCS'contains two redundant divisions (1 and 2)' of incident detection sensors and control logic.
Each division is subdivided into two redundant channels (A and B).
The logic is cnergized to trip.
Both channels in only one division must be tripped to initiate the-RRCS ATWS prevention and mitigation
-actions.
Consequently, the failure of one RRCS logic channel will not prevent actuation of RRCS or initiation of the cppropriate ATWS prevention and mitigation actions, nor will the failure of.one RRCS logic channel cause the inadvertent actuation s
..of RRCS 'orl initiation of the ATWS prevention and mitigation features.
RRCS Division 1, channels A and B, are powered by the 125 Vdc Bus A (Division 1), and RRCS Division 2, channels A and 1
B, are powered by the 125 Vdc-Bus B (Division 2)._.The power-Eupplies to the RRCS are available during all potentia 1'ATWS j
- initiating events, including those events involving loss of I
normalLpower supplies.
The RRCS is continuously self-monitored by a solid state j
ricro-processor' based, self-test system.
The self-test system continuously checks and. updates the status of the RRCS sensors, l
logic, and. output devices.
An alarm results from abnormalities in the RRCS.-
The RRCS is also periodically verified operable via manual surveillance testing.
The requirements contained in 10 CFR 50.62 applicable to
. boiling water reactors are as restated below followed by a description of our current.conformance'to the Rule for Limerick L
-Generating Station, Units 1 and 2.
Paragraph (c)(1)~ Requirements g
Not applicable to BWR's.
. Paragraph (c)(2) Requirements i.
l Not applicable to BWR's.
Paragraph (c)(3) Requirements Each boiling water reactor must have an Alternate Rod Injection (ARI) system that is diverse (from the reactor trip system) from censor. output--to the final actuation device.
The ARI system must have redundant scram air header exhaust valves.
The ARI must be designed to perform its function in a reliable manner and be independent (from the existing reactor trip system) from sensor output to the final actuation device.
2850044570 Mr. Harold R. Denton October 17, 1985 Page 4 Response to Paragraph (c)(3)
Upon actuation, the RRCS immediately initiates ARI by energizing the eight ARI valves located on.the scram air headers and air supply.'
Four ARI valves are assigned to each division of RRCS.
Either division of four ARI valves is sufficient to depressurize the scram air headers to allow all control rods to begin to insert within 15 seconds.
The existing reactor trip system utilizes Reactor Protection System (RPS) incident detection and control logic and scram air
. header vent va ves to initiate a scram.
The logic is de-l energized to operate.
The ARI utilizes the RRCS which is separated from the RPS.
The RRCS contains dedicated incident
' detection sensors and logic which is energized to operate.
ARI is diverse from the existing reactor trip system.
Two divisions of RRCS and ARI valves are provided for redundancy..Both RRCS and the ARI. valves are designed to function in a reliable manner and are independent from the existing reactor trip system.
The design of the ARI and RRCS satisfies the requirements of-10
~
CFR 50.62(c)(3), the quality assurance guidance, and the system and equipment guidance contained in references 1, 2, and 3, respectively.
Paragraph (c)(4) Requirements Each boiling water reactor must have a Standby Liquid Control System (SLCS) with a minimum flow capacity and boron content equivalent in control capacity to 86 gallons per minute of 13 weight percent solium pentaborate solution.
The SLCS and its injection location must be designed to perform its function in a reliable manner.
The SLCS initiation must be automatic and must be designed to perform its function in a reliable manner.
'i Response to Paragraph (c)(4) 4 The Standby Liquid Control System (SLCS) has a minimum flow capacity of 86 gallons per minute (maximum flow capacity of 129 gallons per minute) of 13 weight percent sodium pentaborate solution and is automatically initiated to inject into the r
i reactor ny the RRCS.
The SLCS, as well as the automatic initiation of SLCS, is designed to perform its function in a reliable manner.
The sodium pentaborate solution is injected into the. core exit plenum by connection of the SLCS piping to the upper core spray sparger piping just external to the reactor vessel.
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2.85.004a570 Mr. Harold R. Denton October 17, 1985
-Page 5 The design of SLCS and the automatic initiation of SLCS satisfies the requirements of 10 CFR 50.62(c)(4), the quality assurance guidance, and the system and equipment guidance contained in references 1, 2, and 3, respectively.
Paragraph (c)(5) Requirements Each boiling water reactor must have equipment to trip the reactor coolant recirculating pumps automatically under-conditions indicative of an ATWS.
This equipment must be designed to perform its function in a reliable manner.
Response to Paragraph'(c)(5)
Upon actuation by either reactor high pressure or reactor vessel low level,Lthe RRCS initiates a trip of the reactor coolant recirculating pumps by tripping circuit breakers in the power feeds to the reactor recirculating pump motors.
The RRCS and the squipment required to trip the reactor recirculating pumps are designed to-perform its function in a reliable manner.
The design of the RRCS and the equipment required to trip the reactor recirculating pumps satisfies the requirements of 10 CFR 50.62(c)(5), the quality assurance guidance, and the system and equipment guidance contained in references 1, 2, and 3, respectively.
Paragraph (c)(6) Requirements Information sufficient to demonstrate to the Commission the adequacy of items in paragraph (c)(1) through (c)(5) of this section shall be submitted to the Director, Office of Nuclear Reactor Regulation.
Response to Paragraph (c)(6)
- An analysis of the design of the RRCS against general functional requirements, various Regulatory Guides and industry standards, and '10 CFR 50, Appendix A, is provided in Final Safety Analysis Report (FS AR) Section 7.6.2.8.
Consistent with accepted industry i
practices, quality controls comparable to selected portions of
' the Appendix B Quality Assurance program in place at the Limerick l
Generating Station, Units 1 and 2, have been applied to the l
design and installation of the RRCS and appropriate equipment in the CRD, Reactor Recirculation, and SLC systems required for ATWS prevention and mitigation.
i
29500M 570 Mr. Harold R.
Denton-October 17, 1 85 Eage 6 9
The systems and equipment installed in Limerick Generating Station Unit 1 and the systems and equipment designed (but not installed) for Unit 2 for ATWS prevention and mitigation as described above, meet the requirements of 10 CFR 50.62 paragraphs (c)(1) through (c)(5), the quality assurance guidance, and the cystem and equipment guidance contained in references 1, 2, and 3, respectively.
We trust the above information is sufficient for NRC concurrence of Limerick Generating Station, Units 1 and 2, conformance to the ATWS Rule, 10 CFR 50.62.
Should you require any additional information, please do n'ot hesitate to contact us.
Very.truly yours, Driginal signed by A L DALTROEE RCB vdw cc:
E. M. Kelly, Senior Resident Site Inspector
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Service List L
cc: Troy B. Conner, Jr., Esq.
Ann P. Hodgdon, Esq.
Mr. Frank R. Romano Mr. Robert L. Anthony Ms. Phyllis Zitzer Charles W. Elliott, Esq.
Zori G. Ferkin, Esq.
Mr. 'Ihomas Gerusky Director, Penna. Bnergency Management Agency Angus Love, Esq.
David Wersan, Esq.
Robert J. Sugaman, Esq.
Kathryn S. Lewis, Esq.
Spence W. Perry, Esq.
Jay M. Gutierrez, Esq.
Atomic Safety 4 Licensing Appeal Board Atomic Safety 4 Licensing Board Panel Docket 4 Service Section E. M. Kelly Timothy R. S. Campbell l
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