ML20098D950
| ML20098D950 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 05/18/1992 |
| From: | PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | |
| References | |
| ON-123-01, ON-123-1, NUDOCS 9206010133 | |
| Download: ML20098D950 (11) | |
Text
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_ _ _ _ - _ _ - _ _ _ _ _ _ _ _ _ _ _ _-[OJS 0 ' GCS-i O A'.,'E 05'/ 2 0/ 9 2 12 : 5 8 NRMS RECiEIPT ACCNOWLEDGEMENT SEQUENCE '# 3924037980 LGS PROCEDURES - APPROVED ORIGINALS--
DI SVRC ODE . .*0N-U1 TO:-NRC OFFSITE PROCEDNO - *> n T *not?castq ons i t s., 60 s d REVISION 000 DATE 0S/18/92 6 ! I HAVE RECEIVED THE SUBJECT MATERIAL SIGNATURE: -----------_-_______________________-DATE:_____________
PLEASE RETURN THIS FDP.M PROMPTLY TO LGS ADMIN. SERVICES (LGS-340- )
WITHIN 15 OAYS OF THE ABOVE-PRINT-0 ATE.
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9206010133 920518 ,
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- DAir Ob/20/9; 12:r e N R '15 DLCUMENT CONTROL F 0 4 *. SE:sENCe # 39240379eo 1
LGS Pt3C[*'ar;S - A+' PROVED URI31NAL3 I STR C 'l M iW-LI
- tSS SivulAT.' LG5-LTC 01 C**NRC CFc5IT- QUTGUING 01 C*
.LG5 TE Als CTr LGS-LIC 03 C**NUNEZ, R. LGS-LTC 01 I*
- MAINT/ILC LIEFADY DC C / r> A L K 01 I** OPERATIONS SUP. CTR. DCC/ WALK 01 I*
- CUNST CL?S LIO DCC/ WALK 01 I** SHIFT MGR OFFICE UCC/ WALK 01 I*
- CONToCL <M CART LG5 $DCC/ WALK 02 I**SUPPT BLnG lib #1 DCC/ BALK 01 I*
- EMFRG. OP. FAC. LG0 JCC/ WALK 01 C**SUPPT BLDG LI3 12 2 DCC/ WALK 01 I*
- IND3 OUTGOING 01 I** TECH. SUPP. C T D, . LGS DCC/ WALK 01 I*
- LGS OFFIC5 DCC/ WALK 01 I**______________________________________*
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REQUESTS FOR CHANGES TO THIS DISTRIBUTION LIST MUST LtE ADDRESSED TO THE ORGANIZATION RESPONSIBLE FOR GRIGINATING THE ATTACHED DOCUMENT (SEE NUCLEAR RELATED 00CUMENT REGISTER (NRDR) FOR RESP. ORG.). THE RESP. ORG._WILL AUTHORIZE THE LOCAL DCC SUPERVISOR TO MAKE THE NECESSARY CHANGES.
ATTACHED IS A COPY OF:
PROCEDNQ hi AFF-LicA.c; CN { h 6 REVISION 000 DATE 05/19/92 g UNCONTROLLED: L I S R A 3. Y , INPO, NUNEZ L-)
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ON-123 BASES, Rev. 0 3924037980 ""9"AM7!jl C 1 p)/ y/DC"'M i;
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) PHILADELPHIA ELECTRIC COMPANY LIMERICK GENERATING STATION ON-123 MISPOSITIONED CONTROL ROD 1.0 SYMPTOMS $
1.1 A control rod not at its desired position.
2.0 OPERATOR ACTIONS 2.1 Stop all control rod motion AND power changes.
Once a mispositioned control rod is identified, it is prudent to evaluate the state of the reactor prior to recovery. Hasty action-may only exacerbate anv undesirable -
conditions arising ~from the mispositioned contval rod, even if the action is to return the control rod:to its desired positio,.
i 2.2 Notify Shift Supervisaon.
Shift' Supervision should always be informed when a reactivity event has occurred.
2.3 IF control rod is_ drifting, THEN enter.ON-104.
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A drifting control rod is indicative of a control rod drive (CRD) system maloperation, and therefere is beyond the scope of this procedure.
2.4 IF control rod is mispositioned by 1 notch position, TREN reposition control rod to correct position AND exit this procedure, OTHERWISE, continue in this-procedure AND contact Reactor Engineering.
In all cases the benefits of moving a control rod one notch to return it to the desired position'and restore core symmetry outweigh any negative-effects of controlling or uncontrolling one core node.
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ON-123 BASES, Rev.-0 Page 2 of 9 CMM:ljm 2.5 IP reactor power is < RWM LPSP,
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THEN go to step 2.9.
With teactor power less than the RWM LPSP, a control rod mispositioned by more than one notch will probably require bypassing the RWM. In any case, the consequences of deviating from the Banked Position Withdraw Sequence (BPWS) and Reduced Notch Worth Procedure (RNWP) must be evaluated by Reactdr Engineering before proceeding.
2.6 IP any of the'following conditions exist, -
TEEN immediately fully insert the mispositioned control rod:
Execution of this step ensures that if a quick check of reactor parameters indicates the presence of or potential for an unacceptable thermal-hydraulic condition, immediate action is taken to place the ccee in_a safer state.
,a. MPLPD from last P-1 is > 0.9 with no qualified Reactor !
Engineer present, P
With MFLPD > 0.9oon the P-1 edit prior to the mispositionIng event, there is significant potential for c. reding the fuel LHGR limit with a'mispositioned control rod. Since such a condition causes immediate harm to the fuel and cladding, it is appropriate to w fully insert the mispositioned control rod and eliminate any local-power peaking concerns. '
- b. Reactor power is OR was > 100% RTP due to control rod motion, as evaluated by a new OD3-2, A mispositioned control rod which adds reactivity to the core when operating at rated conditions will cause the reactor to exceed its rated power. Since this is a violation of Tech. Specs., immediate-corrective action is warranted. If power was reduced per OT-104 with core flow, insertion of the control rod is still appropriate due to high-local power.
- c. Mispositioned control rod is positioned at the same netch position as another control rod within a 5 x 5 array centered on the mispositioned control-rod, When two adjacent or.nearly-adjacent control rods are at the same axial position, unacceptable power-peaking occurs immediately above the blade _ tips.: Since such a condition'causes immediate harm to the fuel and cladding, it is apprcpriate to_ fully insert the O mispositioned control rod and-elimincte any local power peaking concerns.
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A ON-123 BASES, Rev. 0
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CMM:ljm
- 1. "LPRM UPSCALE" annunciator alarms, Alarming of the "LPRM UPSCALE" annunciator indicates'a sudden increase in local core power to possibly unacceptable levels. Since such a condition could' cause immediate harm to the fuel and cladding, it is ,
appropriate to fully insert the mispositioned control 1
rod a,nd eliminate any local power peaking concerns.
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OTHERWISE, go to step 2.8.
2.7 Pully insert the control. rods necessary to achieve symmetry, AND demand a P-1:
Core symmetry ensures that the process computer accurately calculates Thermal Limits and the cots power distribution,
- a. IP all thermal limits are < 0.95, THEN contact Reactor Engineering for reactor power recovery, AND exit this procedure.
Wl.th all Thermal Limits < 0.95, sufficient margins exist such that no reactor parameter limits will be exceeded due to Xenon transients before a-Reactor I~')
\~ ,/ Engineer can initiate a recovery.
- b. IP any thermal limit > 0.95, TEEN reduce reactor.p5wer in accordance-with-the Reactor Maneuvering Shutdown Instructions until a P-1 indicates that all Thermal Limits < 0.95.
i Power-reductions required to achieve a 5%. thermal margin should be performed in.a' controlled uniform )
manner. Therefore, it is appropriate-to,use the Reactor Maneuvering Shutdown Instructions which.are pre-approved and readily available,
- c. Contact Reactor Engineering for recovery, AND exit this procedure.
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ON-123 BASES, Rev. 0 Page 4 of 9 CRM:ljm c
() 2.8 Evaluate whether misp sitioned control rod may be returned to its desired position:
Mispositioned control rods should not, in. general, simply be returned to their desired position. Each individual situation must first be evaluated to determine what action is appropriate.
2.8.1 demand an 007-2.
The OD7-2 edit provides the operator with the- -
current control rod pattern. This information is necessary to evaluate which corrective action is appropriate,
- a. IP control rod was mispositioned by being withdrawn past its desired position, THEU go to step 2.8.3.
Self explanatory.
2 8.2 IP the control rod was mispositioned by'being IEserted past its desired position, AN.D:
- a. The mispositioned control rod must pass through the (j notch position of any control rod in a'5 x 5 array
' centered on the mispositioned control cod in order to be returned to its desired position, THEN fully insert the mispositioned control rod.
unless directed otherwise by a qualified on-shift Reactor Engineer, AND go to step 2.7..
A conttol' rod should never be withdrawn above 80%
RTP, dut to local power peaking concerns when that~
action. wculd involve " crossing tips",.or causing a condition s'herse two adjacentior- nearly- adjacent =
control roc's would be at the same notch position.
A 5x5 array is chosen because'neutronic. coupling.is assumed to occur across a distance of three control cells. For the purposes.of.this procedure _ coupling is defined as two times the mean free-path (40 cm) of a neutrcn witn the reactor at rated temperature and with a'i average void f raction. Additionally, the contrcl rod's current notch position may be causing u1 desirable power peaking. Therefore, the mispositioned control rod should be fully inserted
-if returning it to the desired position would' necessitate " crossing tips".
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Page S of 9 CMM:ljm NOTE: Reactor axial relative power is i'ndicated in the top center of the P-1 edit. Location-1 is at core bottom, and -
location 12 is at core top. One location-increment is equivalent to 2 even Control Rod notch positions.
Example ,
Rod Position 46 42 38 34 30 26 22 18 14 10 06 02 LOCATION 1 0 3 4 5 6 7 8 9 10 11 10 AXIAL REL PWR 0.48 0.79 0.89 0.99 1.08 1.15 1.17 1.20 1.00 1.01 1.11 0.74 REGION REL PWR 0.87 1.08 0.87 1.07 1.33 1.07 0.87 1.08 0.86 RING REL FWR 1.05 1.37 1.32 1.30 1.35 1.21 0.92 0.48 APRM GAF 1.00 1.00 0.99 1.00 0.90 1.01
- b. The mispositioned control rod ~must pass from a location of lower axial relative power to a location of higher axial relative power as O indicated by the last P-1, THEN fully insert the mispositioned control rod unless directed otherwise by a qualified on-shift Reactor Engineer, AND go to step 2.7.
Without a qualified Reactor Engineer.present and-without the use of the predictive-codes'in the Process Computer it is not prudent to withdraw a control blade into a region of higher. axial power.
Such an action results in significant local Xenon transients and axial shifts in reactor power.
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ON-123 BASES, Rev. 0 4
, Page 6 of 9-CMM:ljm CAUTION X X X X X X X X X X F X X X X X X X X XX X X X X X X -X X X X X'X To preclude violation of Thermal Limits AND rated power all control rod withdrawals-greater. than a total of four notch positions shall be performed with a qualified on-shift Reactor Engineer _present except for execution of the Reactor ManeLYering Shutdown Instructions, including the Shutdown RWM.
X X X X X X.X X X X X X X X X X X X X X X X X X X X X X X X' X X X
- c. IF the control rod was mispositioned by more_-than;a i total of 4 notch-positions, THEN fully insert the mispositioned control rod unless directed otherwise by a qualified on-shift Reactor Engineer, AND go to step 2.7.
This caution is a' reminder that su'ustantial reactor maneuvering expertise is required when-large~ _
control rod movements are performed.- The four'.
notch limit is a balance between the benefits of returning the control rod to its desired position
' T and the nazards of unmonitored axial flux shifts-caused by large contro1~ rod motions. This is-especially true when :he core configuration is not as specified on the target control rod pattern, -
- d. OTHERWISE return the mispositioned control rod to its destreo position using single: notch withdraw commands:
If conditions in a., b. and c. above-do not exist I then a mispositioned control rod may.be: withdrawn-to its desired position.
- 1. IF the RBM does not permit withdrawal ot the mispositioned control rod to,its desired position.
THEN fully insert the mispositioned control rod unless directed otherwise by a qualified on-shift Reactor Engineer, AND go to step 2.7..
When the mispositioned control rod cannot be returned to the: desired position, it is prudent to fully insert the control rod rather than leave-it at an intermediate' position without a-proper evaluation, b
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ON-123' BASES, Rev.--O
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- 2. Demand a P-1 once the mispositioned control rod O- has been returned to its desired position.
Depending upon the length of time which the control rod was mispositioned, significant
, local Xenon transients may have occurred. Once core symmetry has been restored, a check of
, thermal-margins by performing a P-1 is prudent.
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- 3. IP any Thermal Limit > 0.98, OR any new Base Crit Codes appear THEN fully insert the mispositioned control rod unless directed otherwise by a qualified on-shift Reactor Engineer, AND go to step 2.7.
OTHERWISE exit this procedure.
The presence of'a Base Crit Code indicates that a significant local Xenon transient may have occurred due to mispositioning of the-control rod. A thermal margin of less than 2% may not "
be sufficient to-ensure that Thermal Limits-are -
complied with during the-local Xenon transient.-
Therefore, it is prudent-to fully-insert the control rod until Reactor Engineering can initiate recovery.
2.8.3 IF the control rod was mispositioned by being wTthdrawn past its desire <1 position, THEN:
- a. Reduce power 100 MWe using-core flow, BUT not to less than 45-mlb/hr core flow.
Control rods which are mispositioned by being withdrawn past the target,. position create a significant potential for' Thermal Limit violations.
A reduction in power by 10%!RTP is appropriate to-mitigate this event.
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ON-123 BASES, Rev. 0 Page 8 of 9 CHM:ljm O
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- b. IP the misposi.tioned. control rod will not pass through the notch position of any control rod in a 5 x 5 array centered on the mispositioned control rod in order to be returned to its proper position, THEN return the mispositioned control rod to its-proper pocition AND:
dontrol rods should not be moved such that'they _
" cross tips" above 80% kTP. If this condition will not occur, then it is appropriate to restore the >
mispositioned control rod.
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- 1. Demand a P-1.
Once core. symmetry has been restored, it is prudent to obtain a P-1 in order to verify that=
Thermal Limits are acceptable.
- 2. - Go to step 2.7.a.
- c. OTHERWISE, reduce power to < 80% RTP using core.
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Flow.
This step is performed if'" crossing tips" must-occur in order to restore:the mispositioned control O rod to its desired position.- Below 80% RTP the local power peaking. caused by having_two adjacent or nearly adjacent control rods at the same notch l position should not.cause a Thermal Limit violation.
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- d. . Return the mispositioned control rod to_its proper-position AND:
- 1. Demand a-P-1.
Once core symmetry has been restored, it is-prudent to obtain a P-1 in order to verify that Thermal Limits are acceptable..
- 2. Go to step 2.7.a.
L9 IP reactor power < RWM LPSP, AND > 10%.RTP, THEN contact Reactor Engineering for recovery.'
With reactor power less than the1RWM LPSP, a control rod
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mispositioned by more than one_. notch will,probably-require bypassing the RWM.- This situation should be evaluated by Reactor Engineering before proceeding.
' ON-12 3 BASES ,: Rev. 0
Page 9 of 9-CMM:1jm
( ) 2.10 IF reactor power < 101 RTP, AND the control rod pattern is-not latched-into the-RWM,
.THEN:
- a. SCRAM
- b. Enter T-100 ,
Mispositioning a control rod below 10% RTP violates the Rod Drop Accident analysis. Therefore the only safe recourse is to scram the reactor.
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