ML20154E978
| ML20154E978 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom, Limerick, 05000000 |
| Issue date: | 09/15/1988 |
| From: | Gallagher J PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Rossi C NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| IEB-88-007, IEB-88-7, NUDOCS 8809190207 | |
| Download: ML20154E978 (10) | |
Text
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PHILADELPHIA ELECTRIC COMPANY 2301 M ARXET STREET P.O. DOX 8699 PHIL ADELPHIA, PA 19101 (als) esosoot September 15, 1988 JOSEPH W. O ALL AOHER
........nu Docket Nos. 50-277 50-278 50-352 Mr. C. E. Rossi, Director U.S. Nuclear Regulatory Commiscion Attn: Document Control Desk Washington, DC 20555
Subject:
NRC Bulletin No. 88"07, dated June 15, 1988, "Power Oscillations in Boiling Water Reactor,"
Peach Bottom Atomic Power Station Units 2 & 3 and Limerick Generating Station Unit 1 Dear Mr. Rossi Philadelphia Electric Company's response to Bulletin 88-07, "Power Oscillations in Boiling Water Reactors" is provided in the Attachment.
This response is for Peach Bottom Atomic Power Station, Units 2 and 3, and Limerick Generating Station Unit 1.
If you have any questions or require additional information, please do not hesitate to contact us, L
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Very truly yours,
%%J W*f O
r Attachment cci Addressee W. T. Russell, Administrator, Region I, USNRC T.
P. Johnson, USNRC Senior Resident Inspector s
T.
E. Magette, State of Maryland T. J. Kenny, Limerick NRC Senior Resident Inspector J. Urban. Delmarva Power l
J. T. Boettger, Public Service Electric & Gas H. C. Schwemm, Atlantic Electric I
8809190207 890915 ADOCK0500g((7 j["df /[
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COMMONWEALTH OP PENNSYLVANIA ss.
COUNTY OF PHILADELPHIA J. W. Gallagher, being first duly sworn, deposes and says:
That he is Vice President of Philadelphia Electric Company, the Licensee herein; that he has read the foregoing response to tJRC Bulletin 88-07 relative to Peach Bottom Atomic Power Station Units 2 and a,
and Limerick Generating Station Unit 1, and knows the contents thereof; and that the statements and matters set
.forah t.herein are true and correct to the best of his knowledge, information and belief.
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v Vice President Subscribed and sworn to before me this I E ay d
of September. 1988.
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Attachment Pcg3 1 of 8 Docket Nos. 50-277 50-278 4
50-352 i
BULLETIM 88-07 POWER OSCILLATIONS IN BWRs i
1 INTRODUCTION I
l Bulletin 88-07, "Power Oscillations in BWRn" describes an unanticipated event at LaSalle in which excessive neutron flux oscillations resulted while the plant was in natural circulation j
after a dual recirculation pump trip.
1 Three actions that must be taken by all BWRs Licenses to ensure l
that correct operator action can and will be taken in the event of uncontrolled power oscillations are described in this l
bulletin,.and are restated prior-to the response for each action.
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Required actions have been addressed for both Peach Bottom Atomic i
Power Statior. (PBAPS) Units 2 and 3, and Limerick Generating
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Station (LGS) Unit 1.
The details of compliance with the
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I requested actions are presented in the following sections.
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LICENSED REACTOR OPERATOR AND SHIPT TECHNICAL ADVISOR l
BRIEPING L
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I Required Action 1)
"Within 15 days of receipt of this bulletin, all BWR I
l licensees should ensure that any licensed reactor l
operator or Shift Technical Advisor performing shift j
duties has been thoroughly briefed regarding the March 9,
1985 LaSalle Unit 2 event."
Response
l Peach Rottom and Limerick I
t All licensed Reactor Operators and Shift Technical Advisors (STAS) have been thoroughly briefed on the LaSalle event l
described in Bulletin 88-07.
This action was completed at LCS by t
June 29, 1988, and at Peach Bottom by July 20, 1988.
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Attcchmsnt Pcgo 2 of 8 i
Docket Nos. 50-277 50-278
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50-352 a
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ADEQUACY OF PROCEDURES AND OPERATOR TRAINING PROGRAMG l
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l Required Actions 2)
"Within 60 days of receipt of this bulletin, all BWR licensees should verify the adequacy of their procedures and operator training programs to ensure that all licensed operators and Shift Technical Advisors are l
cognisant oft i
a.
those plant conditions which may result in the I
I initiation of uncontrolled power oscillations
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i b.
actions which can be taken to avoid plant conditions which may result in the initiation of uncontrolled power oscillations c.
how to recogniac the onset of uncontrolled power
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j oscillations, and r
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actions which can be taken in response to l
l uncontrolled power oscillationa, including the need j
i to scram the reactor if oscillations are not j
l promptly terminated.
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E.t8Panse:
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Applicable procedures and operator training programs were reviewed to verify their adequacy by July 15, 1988 at LGS, and by l
Aug. 30, 1988, at PB.
The three conditions that may rer, ult in
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uncontrolled power oscillations are: 1) as a result of a L
recirculation pump (s) trip, 2) during startup and shutdown, 3) f l
rod sequence exchanges.
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f PEACH BOTTOM i
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Peach Bottcm procedures relating to the three operating i
i conditions of concern -- startup/ shutdown, rod sequence f
l exchanges, and recirculation pump trips have been reviewed to f
determine their adequacy in addressing the concerns of Bulletin j
88-07.
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7-i AttcchMont Pcgs 3 of 8 Docket Nos. 50-277 50-278 i
50-352 Recirculation Pump Trip Condition i
i The most probable event that could result in a high power / low flow situation is a trip of one or two recirculation pumps, particularly from full power.
The review of Peach Bottom t
procedures identitled the need to revise the procedure dealing with Recirculation Pump Trips (OT-112) in order to ensure operator recognition of potential and actual power oscillation conditions, and take proper actions to avoid or deal with these oscillations.
I The following changes were made to the Recirculation Pump Trip 1
procedure.
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o The bases fct 0T-112 have been reviued to include i
explanations of power oscillations-and the conditions that may result in the initiation of uncontrolled power oscillations.
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Procedure OT-112 has been revised to specify the 5
immediate actions to be taken on the loss of one or more l
Recirculation Pumps.
These actions are designed to avoid plant conditions that may result in the initiation of uncontrolled power oscillations.
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o A table of LPRMs has been incorporated in OT-112 to give i
operators specific instruments to monitor and criteria j
for recognizing uncontrolled power oscillations.
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Dased on criteria speelfied in OT-112, operators will scram the reactor if oscillations are not promptly terminated.
Procedure OT-112 is included in Cycle 88-03 of Licensed Operator Requalification training on the Simulator between August 8 -
September 30, 1988.
All Licented Control Room Operators, Staff SRO*, and Certified Instructors will complete this training cycle.
Training on OT-112 will be administered to the current SRO license class during the appropriate module scheduled within that program.
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Attachmont
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Page 4 of 8 1
Docket Nos. 50-277 50-278 j
50-352 1
Startup and Shutdown Conditions i
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i It was not necessary to make changes to procedures concerning f
startup/ shutdown since current procedures adequately address the
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concerns of the Bulletin.
OP-2, Normal Plant Startup, requires l
that the reactor not be operated in regions of high powor/ low flow, where power oscillations are likely to occur.
If the reactor must be operated in these regions, special surveillances are required to be conducted to keep the operators aware of t
potential power oscillation conditions.
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During shutdown, operate s are required to insert rods to below L
j the limits of Technical Specification Figure 3.6.5, "Thermal i
i power and Core Flow Limits of Specification 3.6.P.3, 3.6.P.4 and i
3.6.P.S."
Below the limit in Technical Specification Pigure 3.6.5, the reactor will not be in the high power / low flow
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condition that is of concern.
This action is taken to ensure t
l that the regions of instability are exited as quickly as i
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- possible, j
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During startup, Reactor Engineering personnel must bo present in l
the control rocm to monitot core stability when power may be in l
i unstable regions spacified by Technical Specifications, or when l
both power is greater than 15% and core flow is less than 50%.
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i Procedure RE-31, Reactor Engineering Startup/ Load Drop 1
Instructions, details core stability monitoring practices during
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startup and shutdown.
ST 3.10 "Core Thermal Hydraulic Stability i
Monitoring" will be implemented whenever reactor power is in f
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regions I or II of Technical Specification Figure 3.6.5.
l Training on appropriate actions, and procedures to use during I
these conditions are included in cycle 88-03 of Licensed operator Requalification training on the Simulator between August 8 -
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j September 30, 1988.
All Licensed Control Room Operators, Staff j
SRos and Certified Instructors will complete this training cycle.
I Hod _ Sequence Exchange conditiens i
Hod Sequence Exchanges are only performed at 50% core flow so that conditions of high power / low flow are not reached.
In I
addition, scram margins are closely monitored.
Procedure RE-31 l
will be revised and in use by October 1, 1988, and will etate i
that deep control rods (notches 08-26) should be inserted as needed to increase the scram margin.
If core flow falls below 50%, then ST 3.10 or RE-31 must be implemented.
These procedures j
require core moni*oring by Reactor Engineering personnel.
Therefore, conditions favorabla to uncontrolled power i
Attachmont Pcgo 5 of 8 Docket Nos. 50-277 50-278 50-352 oscillations are not likely to exist during rod sequence exchanges.
Adequacy of Peach Bottom Procedures - Conclusion As a result of the procedures review, the procedure addressing Recirculation Pump Trip condition has been revised to be adequate.
Procedures covering the other two conditions were found to be adequate.
Training on appropriate actions, and procedures to use during these conditions are included in Cycle 88-03 of Licensed Operator Requalification training on the Simulator between August 8 - September 30, 1988.
All Licensed Control Room Operators, Staff SROs and Certified Instructors will complete this training cycle.
LIMERICK l
Each of the three areas of potential instability delineated above I
are avoided by procedure or Reactor Engineering practice at Limerick Generating Station.
I Recirculation Pump Trip Condition l
The most probable event that could result in a high power / low flow situation is a trip of one or both recirculation pumps.
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Procedure OT-112, Recirculation Pump Trip, specifically provides i
an immediate operator action to fully insert deep rods (notches 08-26) fully to prevent a scram.
The follow-up action is ta insert control rods as required to reduce reactor power to below l
the limit specified in Tech Spec Figure 3.4.1.1-1.
By inserting control rods, the high power / low flow condition susceptible to power oscillations is avoided after a recirculation pump (s) trip.
i The Bases for 0T-117 specifically addresses the need for I
inserting control -
a to eliminate the possibility of sustained l
power oscillations "t-112 is addressed in the classroom in Licensed Operator - anning, course LOT-1540, and is practiced in the Simulator by Simulator Training Scenario, "STS-13".
Startup and Snutdown Conditions During startup, Recirculation Pump speed is increased to 28% (20%
feedwater runback limit) to ensure that core flow is greater than 45% as power is increased.
GP-2, Normal Plant Startup, not only
Attachm2nt Page 6 o! 8 Docket Nos. 50-277 50-278 50-352 raises Recirculation Pump speed to 28%, but at appt.;ximately 10%
rated thermal pcwer, total core flow is verified to be greater than 45%.
If core flow is less than 45% and power is greater than Technical Specification Figure 3.4.1.1-1, ST-6-107-880 *,
APRM and LPRM Noise Level Determination, is performed to determine APRM and LPRM noise levels.
These baseline noise levels can then be used to monitor core stability as power is increased by 5% increments.
GP-2, Normal Plant Startup, is addressed in Licensed Operator Training, course LOT-1530 and is practiced in the simulator by Simulator Training Scenarios STS-29, 29A and 30.
Technical Specification 3.4.1.1-1 is specifically addressed in Licensed Operator Training, course LOT-1840 Technical Specification Selected LCO's.
During performance of GP-4, Rapid Plant Shutdown to Hot Shutdown, recirculation flow is reduced to minimum, and the plant is quickly scrammed so that any high power / low flow situation is quickly exited.
GP-3, Normal Plant Shutdown, instructs the operator to utilize Reactor Maneuvering Shutdown Instructions provided by Reactor Engineering in accordance with RE-201, Reactor Maneuvering Plan Approval.
These instructions provide for the insertion of sufficient control rods prior to reducing both recirculation pumps' speeds to minimum so that reactor power is below the limit in Technical Specifications Figure 3.4.1.1-1, thus preventing entry into a high power / low flow condition.
According to GP-3 Operations personnel verify that reactor power is less than Tech Spec Figure 3.4.1.1-1 when core flow is less than 45% and perform ST-6-107-880 *, APRM and LPRM Noise Level Determination, if reactor power is above the limit.
Therefore, if a high power / low flow condition is entered APRM/LPRM noise levels will be monitored.
GP-3 and GP-4 are addressed in License Operator Training (LOT-1530) and plant shutdown is practiced in the simulator by Simulator Training Scenario STS-17.
Hod Sequence Exchange Conditions Since Limerick is a control cell core, total sequence A and B exchanges are not performed.
Deep / shallow rod exchanges are performed between RSCS Groups 9 and 10 but do not occur in areas susceptible to instability.
Power and flow are reduced to conduct this reactor maneuver.
However, recirculation flow is not reduced to minimum, maintaining core flow greater than 45%.
The rod sequence exchange between RSCS Group 9 and 10 is performed and recirculation flow increased.
Therefore, conditions favorable to uncontrolled power oscillations are not likely to exist during rod sequence exchanges.
Attcchmont Pcg3 7 of 8 Docket Nos. 50-277 50-278 50-352 Adequacy of Limerick Procedures Conclusion Specific details of how to recognige uncontrolled power oscillations and the actions required in response to power oscillations were not previously included in the pro edures.
The applicable procedures have been revised to include specific actions, such as instituting a scram and other actions, needed to identify and mitigate excessive power oscillations after control rods are inserted to reduce reactor power to less than the Technical Specification limit.
In addition to the initial briefing, Licensed Operator Requalification training will be given to addressBulletin 88-07, "Power Oscillations in BWRs",
and the procedural changes noted above, and will include a simulator demonstration incorporating power oscillations.
The current procedures, therefore, address those plant conditions (recirculation pump trips, startup/ shutdown and rod sequence exchanges) that can lead to power oscillations.
Specific actions (inserting control rods after a recirculation pump trip, maintaining core flow greater than 45% on startup/ shutdown and deep / shallow exchanges) are in the procedures to prevent plant conditiens that could result in uncontrolled power oscillations.
ADI:QUACY OP I NSTHUMF:NTATION An additional requented action presented in the Hulletin la rentated below:
"Addresneen should also verify the adequacy of the inst rumontation which in relied upon by operators within their procedures."
Heaponne:
Ieach Dottori and Limerick l
The existing pcwer range neutron monitoring instrumentation has been evaluated and determined to be adequate for monitoring rmutron flux oscillations.
The ev31uation and determination were completed by August 8, 1988, for both LGS Unit 1 and PBAPS Units 2 and 3.
The Local Power Range Monitors (LPRMs) installed at both Peach Bottom and Limerick are designed to supply an ionization current proportional to the core neutron flux without suffering ficm a loss of saturation plateau.
The detector output will re:aain linear (plus or micas it) over a range of neutron
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Attechm3nt Pcgo 8 of 8 Docket Nos. 50-277 50-278 i
50-352 l
flux that is sufficient to accommodate local flux peaks of a magnitude on the order of those experienced at LaSalle.
The applicable drawinge for Peach Bottcm and Limerick have been reviewed, and it has be determined that the installed instrumentation has not
'en modified in such a way as to prevent the detection of oscillat.ons (as had occurred at LaSalle).
Both Peach Dottom and Limerick have GC power range neutron monitoring instrumentation installed.
The adequacy of GE supplied power range neutron monitoring instrumentation to detect flux oscillations is discussed in GE Service Information Letter (SIL)
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380, Rev.
1, the methodology of which was endorsed by the NRC as l
documented in NRC Generic Letter 66-02, "Technical Resolution of l
Generic Issue B-19: Thermal-Hydraulic Stability".
Both Peach Bottom and Limerick have implemented SIL 380, Rev. 1.
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cowcLustow t
As presented in the analyses above, procedures, training, and instrumentation at Peach Bottom Atomic Power Station, and l
Limerick Generating Station adequately fulfill the requirements
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in the actions requested of the licensee in Bulletin 88-07, Power l
Oscillations in Boiling Water Reactors.
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