ML19344B591
| ML19344B591 | |
| Person / Time | |
|---|---|
| Site: | La Crosse File:Dairyland Power Cooperative icon.png |
| Issue date: | 09/12/1980 |
| From: | Linder F DAIRYLAND POWER COOPERATIVE |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19344B592 | List: |
| References | |
| LAC-7138, NUDOCS 8010210594 | |
| Download: ML19344B591 (10) | |
Text
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DAIRYLAND
[#/((M[COOPERAT/VE eo Boxa:7 2615 EAST AV SOUTH
- LA CROSSE. WISCONSIN 54601 (608) 788 4 000 September 12, 1980 In reply, please refer to LAC-7138 DOCKET NO. 50-409 Director of Nuclear Reactor Regulation ATTN:
Mr. Dennis M.
Crutchfield, Chief Operating Reactors Branch #5 Division of Operating Reactors U.
S. Nuclear Regulatory Commission Washington, D.
C.
20555
SUBJECT:
DAIRYLAND POWER COOPERATIVE LA CROSSE BOILING WATER REACTOR (LACBWR)
PROVISIONAL OPERATING LICENSE NO. DPR-45 ANTICIPATED TRANSIENT WITHOUT SCRAM
References:
(1)
DPC Letter, LAC-2788, Madgett to Giambusso, dated October 9, 1974.
(2)
NRC Letter, Stello, Jr.,
to Madgett, dated August 31, 1976.
(3)
DPC Letter, LAC-4270, Madgett to Stello, Jr.,
dated October 13, 1976.
(4)
NRC Letter, Ziemann to Madgett, dated May 15, 1978.
Gentlemen:
Please find enclosed as Attachment 1, DPC's response to the NRC staff request (Reference 4) concerning a plant modification for Anticipated Transient Without Scram in accordance with NUREG-0460.
The changes to Technical Specifications are also in Attachment 1.
We have determined that a fee is not necessary since.the required changes resulted from a written request from the Commission (Reference 2).
If there are any questions concerning this submittal, please contact us.
Very truly yours, DAIRYLAND POWER COOPERATIVE gI
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Frank Linder, General Manager FL:RB:af A
Enclosure:
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Keppler,. Reg. Dir., NRC-DRO III 80 lO M RC Resident Inspectops
ATTACHMENT 1 ANTICIPATED TRANSIENT WITHOUT SCRAM 1.
SUMMARY
2.
INTRODUCTION 3.
RECIRCULATION PUMP TRIP SYSTEM DESCRIPTION 4.
CONFORMANCE TO NRC/IEEE CRITERIA 5.
TECHNICAL SPECIFICATION CHANGES 6.
SCHEDULE 7.
REFERENCES d
' ATTACHMENT l-1.
ISUMMARY
.The safety analysis. of the LACBWR plant with respect to the
. criteria: established in the AEC Technical Report on Anticipated
. Transients Without Scram '( ATWS), -(WASH-1270),. indicated that the plant. could ' sustain without; damage all A'1WS events except those involving the. loss of;the main condenser heat sink.
In order.to accommodate this type'of ATWS event, a plant improvement.is lnecessary which will' provide a backup reactor shutdown system.
This can. be. accomplished by tripping the recirculation -pumps on
~
a high' reactor pressure.
-DairylandJPower, Cooperative has' agreed to provide this plant modi-fication and the' details of the circuit changes are presented in this report. ~The contents of this submittal were discussed with
-Messieurs James Shea and Paul Shemanski of the NRC on June 10, 1980, and determined to be rimilar.to the Monticello design and
. acceptable'for installation at LACBWR.
-2.
INTRODUCTION In September, 1973, the Atomic Energy Commission (AEC)-published the " Technical Report on Anticipated Transients Without Scram for Water-Cooled Power Reactors," (WASH-1270), which established acceptance criteria for anticipated transien'ts without scram (ATWS).
Subsequent to theipublication of WASH-1270, the AEC requested Dairyland Power Cooperative (DPC) to address certain sections of
- WASH-1270, as applied to the La Crosse Boiling Water Reactor (LACBWR).
DPC's response (Reference 1) was incorporated into the full-term operating license application for LACBWR..' Based on its ATWS analysis for LACBWR, DPC concluded that LACBWR can presently, with no modifications, withstand all ATWS events except those that result in.a loss of.the mainLcondenser as a heat sink.
DPC also concluded if the plant were modified to include a recirculation pump. trip at high reactor pressure, no damage to the reactor would occur for all
'ATWS events.
l L
Based on.its review of Reference l'and the generic analysis of General' Electric for all: boiling water reactors, the Nuclear.
Regulatory Commission (NRC) has stated in Reference 2 that the addition-of a' recirculation pump trip would'significantly limit l
the consequences of an'ATWS event.
A trip'of the recirculation pumps-in the event of high reactor vessel pressure has tdue effect of causing an increase in the moderatorfvoids'in the-reactor core.: A substantial' negative reactivity results, and the power -and pressure surges that might
'otherwise. occur in'the most: limiting transient (MSIV closure) are L
.substantially reduced.. With Lthe recirculation pumps shut' down,
~
the reactor ' power will e be reduced: to a. steady-state powe r level of less; than 20% '(based 'on natural circulation. through the~ core).
- t.,
- 'O e
ATTACHMENT'l' In ReferenceL2, the NRC also requested DPC to make a commitment to modify _ LACBWR to provide a ' recirculation pump trip.. DPC has committed' to the design of a recirculation pump trip system in Reference 3.
Subsequently' in Reference 4, NRC requested additional
.information (logic and schematic diagrams,- description of.confor-mance to IEEE-279, Technical Specification changes, and implementa-tion schedule) which is provided in'this report.
3.
. RECIRCULATION-PUMP TRIP' SYSTEM DESCRIPTION The Recirculation Pump Trip System (RPTS). described herein has -
been designed to be independent and separate from canponents and/or systems that initiate the anticipated transient of main steam iso-lation valve closure.
In addition, the RPTS is independent, separate-and ' diverse to the extent feasible from the normal scram system, to minimize the probability of any detrimental interaction
' between the two reactor shutdown systems.
Referring to Figures _1 thru 8, the LACBWR RPTS will perform the function of disconnecting the main power to both reactor recircu-lation pump circuit ~ breakers in the event'of RPT conditions in either of the redundant logic trains.
- A RPTS' trip signal consists of high reactor. pressure
(> 1350 psig) or low reactor' water level (-30 inches).
A high pressure signal
.upstremm'of,the MSIV's'provides an indication that either MSIV has closed.
Should'the pressure sensors fail' to trip the' pumps, the
. pressure will continue to increase causing the relief valves to
~ lift, thus blowing down the reactor. - The water level will continue to decrease below the reactor low water level scram setpoint
(-12 inches).
At a reactor water level of -30 inches, the RPT level backup system will actuate.
l The component.s to be added are manufactured by Foxboro-Company and are designed for use in the -Consoltrol equipment line presently in. service at LACBWR.
The pressure and level relays are arranged in a two out of 'three logic to energize the recirculation
~
pump trip: relays (TR1 and TR2).
A signal from any one of the four logic trains will trip both pumps. _ The bypass switch' will' permit pump. operation should the RPTS control circuit f ail' in the shutdown mode and recirculation pump operation is required.
This logic system :is not-_ vulnerable to any single. failure either preventing a
. pump trip when required or causing a pump trip when not required.
Siemens-Allis, manufacturer of the' recirculation pump breakers, does not recommendfthe addition of a second trip coil.
Breakers-with1 dual coils were not designed'until_-1968.-
The breakers provided for LACBWR are.of_a 1963 vintage.
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s ATTACHMENT 1 f
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'4.
CONMORMANCE TO NRC/IEEE CRITERIA L
Reference 4 're' ques _ted 'a -detailed point-by-point -description of how LACBWR's. proposed _ RPTS meets: the ~ criteria specified in.the :enclo-sure(tolReference 4.s.lThe following information is keyed to those L
'm~
specific ' criteria andidelineates 'dae. degree of conformance of.
_LACBWRts RPTS to:tho'se criteria..
i A.-
General Fucntional Requirement.
IThe RPTS; shall ' automatically shut down 'both reactor. recirculation '-
pumps.whenever reactor steam pressure or' reactor water level' reach 'the preset trip levels specified in' Section ~ 3.
.B.. - Independency' and Integri ty -
The primary. protection from= an ATWS is independent and separ-g ateifrom. components l and/or. systems that finitiate MSIV ' closure
-which in t turn creates-- the postulated high pressure condition if
.a. reactor scram:does: not occur.
The backup: reactor level RPT protection does. share common current loops.which-may initiate L
an-MSIV' closure.
Thesec current loops.have demonstrated a high -
' degree of operational reliability during the life of the plant.
The RPT signal would be sensed external to and independent from7the drawers'which.may initiate thelATWS.
l_
The'RPTS and its' components shall be diverse from=the1 normal scram system ^toJthe extent feasible _to minimize the probability l.
of' the high pressure ATWS disabling the operation ~ of tha' mitigating - system '(RPTS).
Diversity is achieved by ~ the following differences ' between the RPTS and the _ scram system:
i l-
-(l) : The.use of relays not typically used >in the' normal'
- scram system.
(2)~ The relays will. trip the recirculation pumps,by
-energizing rather than de-energizing.
(3)-.The'RPTS logic will'use AC power.
iI' (4)
The sensing device uses an independent power supply.
LThe/RPTS: and ' its components shall not' be disabled as i consequence ofJthe high pre'ssure: ATWS_ event.
'All ' additional' RPTS components e
will' beiinstalled"outside.the~ Containment Building,
/
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LAdditionfof new sensing devices was determined'to: offer no-Lincrease=in reliability.or/ independence.- There. presently exists
'suf ficient-LindicatingEand control sensors for the safe - operation
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of ithe - plant.nWith the limited (numberL of.rensing lines -avail-Lable,nsome of the. transmitters share common legs.
-Adding f additional -sensors would compound this condition' and" complicate 2 maintenance. ' As;a: result, the"possib i lity. of _ main tenance - errors woul~d1 increase. 11so: by using l exis; ins instrumentation, no?
cadditionali containment) penetra tions are required. ; ~ There. ~are few.
- spare : penetrations and'. toiinstall?additiona1 sensors would also Erequireinewjpenetrationsnto:be:drilleu andGtested._
4>.
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ATTACHMENT 1 C.
RPTS Interaction with Control Systems and Scram Systems One of the ' reactor pressure channels provides an input signal
~ to the Main Steam Turbine Bypass Valve Controller.
This channel is isolated from the remainder of the control circuit by the ' controller.
Any malfunction downstream of the control-ler will not prevent the RPT circuit from functioning if required.
All associated components in ' this current loop will be considered ~p' art of the RPTS.
As stated previously in Section B, the three level channels and two of the pressure channels will share common current loops with the scram system.
The current loops have indepen-dent power supplies separate from the safety drawers.
The.
safety system scram actuations are initiated through a power supply, mmplifier, comparators and relays in the safety drawers.
Any failure of these components would not effect the signal to the RPT circuits and therefore not disable the mitigating system.
The reactor steam pressure safety channels will scram the reactor on the loss of power to the safety drawer or current loop.. A loss of power to the safety drawer will have no detrimental effect on the ability of the current loop to monitor for an ATWS and initiate a RPT.
As a backup system, the reactor water level channels will pro-vide both a scram and RPT logic input on a low water level signal, loss of water level signal or loss of power to current loop.
If the loss of power occurs in the level drawer, a reactor scram would be initiated.
A drawer malfunction would not caus'e nor prevent a RPT from occurring if required.
.One of the three reactor water level safety channels does not have a safety drawer.
It consists of a basic current loop with a transmitter, power supply, amplifier, indicator, and trip relay.
A low water level signal, loss of water level signal, or loss of power will scram the reactor and actuate an input to the RPT circuit.
If the postulated ATWS occurs, the RPT components will actuate independently from the scram systems to de-energize the-recirculation pumps.
The basic steam and level channel current loops shall be classified as part of the RPTS.
The recirculation pump circuit breakers which will be used for
-both normal control of the recirculation pumps and as part of
-the RPTS, shall be classified as part of the RPTS.
The RPTS trip signal to the recirculation pump circuit breakers over-
~
rides any control signal to start the pump motors.
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v ATTACHMENT 1
~D.
-Equipment'-Qualification Since. no ' additional equipment is to be added toi the containment, environmental ~. equipment qualification is not required.
However, components added external to the containment will-be
. purchased equal to or superior. to. originally supplied equipment.
i Periodic Surveillance and Preventive Maintenance Testing E..
and Calibration RPT' system testing and calibration shall be performed annually-during refueling outages.
These operations will'be conducted as partiof the routine sensor calibrations.
Due to the' relative simplicity of the RPTS activation system and the high reliability of its camponents, and since the
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. recirculation pump circuit breakers cannot be tripped for testing purposes during power operation, no scheduled periodic testing will be performed.
.F.
' Quality Assurance A' Quality-Assurance Program in conformance with the require-ments of 10CFR50, Appendix B, shall be-applied to the RPTS
,~
design and installation.
Since the components required for the RPTS are' generally commercial, off the shelf items, it may not-be possible to certify manufacturing compliance to 10CFR50, Appendix B.
DPC,'however, will only use high quality componentsLin the LACBWR RPTS equal to or better than existing plant - equipment. -
~
G.
Administrative Controls Administrative controls shall be established to control access to all'RPTS set point-adjustments and bypasses.
-H.
Information Readout-The -RPTS is designed to provide the operator with:.
(a) an annunciator. alarm 'if a RPTS trip signal to the recirculation pumps is generated, and -(b)t an annunciator alarm if one or both keyswitches ~are in:the bypass position.
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Any changes of;the-pressure andllevel contacts from normal operating 'stateDwill be annunciated by a combination of active monitoring and - by ' a bypass ' switch -test circuitato be used prior
[to required periodic: testing of the level and pressure circuits.
2
- I.
Maintainability'-
Maintainability is.an inherent feature of the RPTS due to the relativelyJsmall number: of components, high : reliability and information readout' (described in H. above).
Theabove
' features 'in addition to. the 'two fout of three trip system' logic facilitates the recogn'ition,4 location, replacement, repair-
- and/o7f-adjustment ~of malfunctioning components.
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ATTACHMENT 1 J.
Availability and Reliability In order to satisfy the availability and reliability require-ments of. Reference 4, the RPTS must satisfy the requirements for a nuclear power plant safety system of IEEE-279, dated 1971 and as supplemented by Sections A through I discussed above.
The following information is keyed to the specific requirements of Section 4 of IEEE-279 and provides the degree of conformance of LACBWR's RPTS to those requirements:
(1)
General Functional Requirement Same as Section A discussed earlier.
(2)
Single Failure Criterion No single failure within the RPTS can prevent the recirculation pumps from shutting down when required.
Additionally, since the RPTS is a backup to the normal reactor scram system, it would be required to operate only if the scram system failed to operate when required.
Because of the independence and diversity between the RPTS relays and the scram system orawers, there is no single failure which could prevent both reactor shutdown systems from operating when required.
(3)
Quality of Components and Modules Same as Section F discussed earlier.
(4)
Equipment Qualification Same as Section D discussed earlier.
(5)
Channel Integrity Same as Section B and D discussed earlier.
(6)
"Sannel Independence Same-as Section B discussed earlier.
(7)
Control and Protection System Interaction Same as Section ? discussed earlier.
(8)
Derivation of System Inputs Same as Section A and B discussed earlier.
s (9)
Capability for Tests and Calibrations Same as Section E discussed earlier.
ATTACHMENT 1 (10)
Capability for Tests and Calibrations Same as Section E discussed earlier.
~
(11)
Channel Bypass or Removal from Operations For testing, trouble shooting, and maintenance, channel bypasses are provided.
The bypasses.will enable detection and location of any change from the normal operating' state of a relay in any of the pressure or level logic inputs.
If one of the three logic inputs is removed from service during power operation, its output shall be manually placed in the tripped state.
This reduces the trip logic to a one out of two requirement, so that a single failure in the RPTS logic network cannot prevent its protective function when required.
(12)
Operating Bypasses No bypasses are required during normal operation.
Bypass switches are provided, however, to permit recirculation pump operation in the event that the RPTS fails in the shutdown mode and pump operation is necessary..
(13)
Indication of Bypass Bypasses are alarmed in the main control room.
In addition, the status of bypasses can be determined by switch positions and lights located in the control room.
The indication system is designed to be in conformance with criteria for safety systems and is designed to preclude the possibility of adverse effects on the plant safety system.
(14)
Access to Means for Bypassing The design permits administrative control of the means for manually bypassing protective functions.
(15)
Multiple Set Points There are no multiple set points.
(16)
Completion of Protective Action Once It Is Initiated The RPTS trip once iniciated will trip the pumps.
When the recirculation pumps shut down, their return to operation requires subsequent deliberate operator action.. - - -
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4
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ATTACHMENT:1
~
"(17). ManualiInitiation
' ?,
- Manual
- initiation ~ of. the recirculation. pump tripxis :
provided-onLthe'contrul room benchboard by operating the manual control switches to-the respective'
~
~
recirculation ~ p6mp' circui t ~ breakers. - Since the.
.manualitrip is independent from the:adtomaticitrip, no '= f ailure 'of '.the automatic. trip circuit can ;
deactivateLthe manual trip capability.
. 1 (18)~ Access' to Setpoint Adjustments,. Calibration, and Test Points Setpoint' adjustment /calibrationais accomplished in the control room' at.the pressure and level relays.
- Access to the pressure and level relays will be administratively controlled.
(19)~ Identification of-Protective Action
't t.
Same as Section H discussed earlier.
(20)
Information Readout
.Same as'Section-H discussed earlier.
( 2.'. )
System' Repair Same :asSection I discussed ~ earlier.-
I (22)
Identification ~
- All-components _ and intercor.necting wiring of-the-RPT isystem'shall; be distinctively identified is being in:
.ttis protective _ system.
This identification shall distinguish;between redundant portions of the:
protective. system.
1 5..
. TECHNICAL ~ SPECIFICATION CHANGES
. See l proposed Technical S' ecification Changes on the following p
^
pages.
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