ML20206U003

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Rev 13 to Nuclear Performance Evaluation Procedure 10.9, Control Rod Scram Time Evaluation
ML20206U003
Person / Time
Site: Cooper Entergy icon.png
Issue date: 07/23/1984
From: Moeller C, Salisbury J
NEBRASKA PUBLIC POWER DISTRICT
To:
Shared Package
ML20206T643 List:
References
10.9, TAC-54682, NUDOCS 8607080283
Download: ML20206U003 (10)
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COOPER NUCLEAR STATION OPERATIONS MANUAL UCLEAR PERFORMANCE EVALUATION PROCEDURE 10.9 CONTROL ROD SCRAM TIME EVALUATION e

I. PURPOSE A. The purpose of this procedure is to provide a proper and safe method to scram time test individual control rod drives (CRD) or to monitor scram times for selected control rods when the computer is operable.

II. DISCUSSION A. Scram time testing CRDs is required by Technical Specification Sections 3.3.C. and 4.3.C. to insure that the reactor can be made suberitical at a rate fast enough to prevent fuel damage during power transients. ,

B. Rod scram tests will be performed at intervals consigtent with Technical Specification requirements and all rods to be scrammed will be selected by the Reactor Engineer. , ,

C. Reactor protection panel 9-16 and rod position indicating system' panel 9-27 in the Control Room will be used to perform individual rod scram tests in accordance with this procedure.-

D. If the process computer is available, it will be used to monitor the' individual control rod under test. Otherwise, a multichannel strip chart recorder will be used to record the CRD times by recording the point at which the scram occurred, the odd rod positions, and the rod full-in position. By knowing the speed of the strip chart recorder the CRD scram time may be calculated for any rod position.

E. For full scrams from power operation with the reactor in the Run Mode, the computer is setup to monitor the drop out from 46, 36, 26, 16, and 06 (notch position) for up to 20 selected control rods. . The control rods to be monitored 'are selected by inserting a patch between the computer input channel and the selected rod location in the rear of.

panel 9-27.

F. If scrams from power operation with the reactor in the Run Mode occur with a frequency of 16 weeks or less, this data will be used to satisfy the testing requirements.

G. Analysis of data vill be performed by the Reactor Engineer (or his designee) using Attachments "A", "B", and "D".

III. REFERENCES A. CNS Technical Specifications Section 3.3.

B.- CNS Technical Specifications Sect. ion 3.11.C.

8607080283 860630 PDR ADOCK 05000298 P PDR R* vised By/Date Reviewed By/Date r te Rev Procedure Page 1 Of J.' Salisbury 6/20/84 C. Moeller 7/19/84 7.;ry-py 13 10.9 __1Q_,Pages

C. G.E. Letter DTI NPPD81-029, dated March 19, 1981, ODYN Option B Scram Time Surveillance Procedures.

D. ' Internal Memo, dated June 20, 1984, CNSS847331, Technical Specification CRD Insertion Point Criteria.

IV. PREREQUISITES

. 'B. All jumpers removed from the CRD system as required (see Section i VI.C.).  !

C. RPIS must be in operation.

4 D. Rod worth minimizer operable when performing the test with the reactor shut down or if it must be bypassed, a second licensed Operator or,

, qualified station personnel will be present and mon,itor all rod with-draws, when required by the Technical Specifications.

E. Telephone communications between panels' 9-5, 9-16, and CRD mod'ules .

should be established. '

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F. The control rod to be scram tested must be fully withdrawn.

V. LIMITATIONS A. Limiting Conditions of Operation - Technical Specification Sections 3.3.B.3.f., 3.3.C.I., 3.3.C.2., 3.3.C.3., 3.11.C., 4.3.C.I., and 4.3.C.2.

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1. Technical Specifications Section 3.3.B.3.f. - The sequence restraints i imposed on the control rods may be removed by the use of the ,

individual rod position bypass switches for scram testing only those rods which are fully withdrawn in the 100% to 50% rod density range.

2. Technical Specifications Section 3.3.C.1. - The average scram insertion time, based on the deenergization of the scram pilot valve solenoids as time zero, of all operable control rods .in the reactor power operation condition shall.be no greater than:

% Inserted Corresponding Drop Out Average-Scram Corresponding From Fully Monitored Of Relay Insertion Scram Insertion Withdrawn

  • Position (%)** Position Times (Sec.)* Times (Sec.)**

5 4.51 46 0.375 0.358 20 25.35 36 0.90 1.10 50 46.18 26 2.00 1.86 90 87.85 06 3.50 3.42

[ *From Technical Specification Sections 3.3.C.1. and 3.3.C.2.

    • See Reference D.

Procsdure Number 10.9 Date %M -7 Revision 13 Page 2 Of 10 Pages

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3. Technical Specifications Section 3.3.C.2. - The average of the scram insertion times for the three fastest control rods of all groups of four control rods in a two-by-two array shall be no greater than:

% Inserted Corresponding Drop Out Average Scram, Corresponding ~

From Fully Monitored Of Relay Insertion Scram Insertion Withdrawn

  • Position (%)** Position Times (Sec.)* Times (Sec.)**

5 4.51 46 0.398 0.38 20 25.35 36 0.954 1.16 50 46.18 26 2.12 1.97

, 90 87.85 06 3.71 3.62

    • See Reference D. .
4. Technical Specifications Section 3.3.C.3. . - The maximum scram insertion tire for 90% insertion of any operable control rod,shall not exceed 7 seconds:

% Inserted Corresponding Drop Out Average Scram Corresponding From Fully Monitored Of Relay Insertion Scram Insertion Withdrawn

  • Position (%)** Position Times (Sec.)* Times (Sec.)**

90 87.85 06 7.0 6.8

    • See Reference D.
5. Technical Specifications Section 3.11.C. - During steady state power operation the MCPR for each type of fuel rated power .and flow shall not be lower than the limiting value shown in Technical.

Specifications Figure 3.11-2. If, at any time during steady state l operation it is determined by normal surveillance that the limiting value for MCPR is being exceeded, action shall then be initiated within 15 minutes to restore operation to within the . prescribed limits. If the' steady state MCPR is not returned to within the prescribed limits within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, the reactor shall be brought to the Cold Shutdown condition within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Surveillance and corresponding action shall continue until the prescribed limits are l again being met. For core flows other than rated the MCPR shall be the operating limit at rated flow times K g, where Kg is as shown in

Technical Specifications Figure 3.11.3.
6. Technical Specifications Section 4.3.C.1. - Af ter each refueling outage all operable rods shall be scram time tested from the fully withdrawn position with the nuclear system pressure above 800 psig j and the requirements of Technical Specifications Section 3.3.B.3.a.

i met. This testing shall be completed prior to exceeding 40% power.

Precadure Number 10.9 Date M 3-f Revision 13 Page 3 of 10 Pages k

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Below 20% power, only rods in those sequences (A12 and A34 or B12 and B34) which were fully withdrawn in the region from 100% rod j

density to 50% rod density shall be scram time tested. During all scram time testing below 20% power, the rod worth minimizer shall be operable or a second licensed Operator or other qualified

! employee shall verify that the Operator at the. reactor consola is l following the control rod progras.

7. Technical Specifications Section 4.3.C.2. - At 16-week intervals, 10% of the operable CRD shall be scram timed above 800 psig.

Whenever such scram time measurements are made, an evaluation shall be made to provide reasonabic assurance that proper CRD performance is being maintained.

B. Administrative Limits.

1. None. ,

VI. PRECAUTIONS , ,

A. If during the performance of this procedure, a Control Room Opefator relief occurs, the relieving Control Room Operator' must demand and review a computer printout of the control rod positions. If the computer is not available, he must obtain a current rod status by observing the rod-in lights and using the 4. rod display.

l B. Do not return the selected rod scram switch on panel 9-16 to the normal j position for at least 5 seconds after scrasming a rod.

C. When using the computer -to time rods, DO NOT remove or insert the

, jumper wires, unless the computer rod timing switch on panel 9-15 is in-

. the normal position. .

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i D. Allow the CRD temperatures to stabilize for about 3 minutes following withdrawal for a hot test scram.

E. If during the performance of this procedure, an incorrect-control rod is scrammed in, the Control Room Operator shall check with the Reactor ~

Engineer for directions on withdrawing the control rod to its original position.

VI

I. PROCEDURE

A. Scram Times With Strip Chart Recorder.

Note: This portion of this procedure is to be used only for strip chart recording of the scram times of individual control rods.

1. This procedure is to be performed under the direction of the Shift Supervisor.

Proc dure Number 10.9 Date '7 ,2 2?- RL[ Revision '13 Page 4 Of 10 Pages L

2. The- Control Room Operator and the Shif t Supervisor shall review the jumper log to assure that existing jumpers do not create an opera-tional safety problem. Special emphasis must be given to refueling interlocks, rod block circuits, RPIS, and RPS.
3. Verify that the reactor protection system is in service' with the

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, IRM and APRM scrams functional.

4. Assure that the rod worth minimizer is in service. if it must be BYPASSED, a second licensed Operator or qualified station personnel will be present and monitor all rod withdrawals, when required by the Technical Specifications.
5. Assure that all control rods are fully inserted or at positions specified in the existing control rod sequence by: ,
a. Checking the 4-rod display for rod positions around the rod to be pulled;

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AND

b. Checking the full core display to determine that the rod full-in lights are on; .-

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c. Demanding a computer printout of the control rod positions.
6. Verify that the CRD accumulators are charged and ready for service.-

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7. Verify that the rod position information system is in operation.
8. At the reactor control console, select the control rod to be tested. Prior to withdrawing an out-of-sequence control rod, obtain the Reactor Engineer's approval. Withdraw the rod to the full-out position. Also, if it is necessary to bypass the rod worth minimizer, observe the Technical Specification requirements.

Note: Allow approximately 3 minutes between end of rod withdrawal and start of scram for hot test scram.

9. Establish telephone communications between panels 9-5 and 9-16 and the CRD accumulator area (Reactor Building 903'). See Attachment "C" for CRD accumulator locations.

10.' Valve out the charging water to control rod accumulator valve 113 for the rod to be tested.

11. Fill out on Attachment "A" for the control rod to be scrammed; rod' i

location, date, reactor powe.r, reactor pressure, and accumulator pressure.

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-Prcesdure Number 10.9 Date '7-42 3 -8'! Revision 13 Page 5 Of 10 Pages

l Note: If the computer is being used in the timing of' control rods, continue with Step VII.B. of this procedure. [

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12. Start and calibrate the multichannel strip chart recorder and connect it to panel 9-16 as follows. Channel 1 to the test jack immediately below the rod scram which corresponding to 'the rod -

selected (with a sensitivity of 5 V/Div). ' Channel'2 (optional) to the appropriate HYDRAULIC MODULES SET (1, 2, _ 3, or 4) VALVE and l Channel 3 to the appropriate phone jack, HYDRAULIC MODULES JMC SET (1, 2, 3, or 4) RODS with a sensitivity of 50 mV/Div (see diagram attached to panel 9-16).

13. Start the_ strip chart recorder and shift the speed to 125 mm/Sec. '

Initiate the individual rod scram by actuating the selected rod scram switch on panel 9-16 to its center (scram) position. ,

Note: Do not return the selected rod scram sw%tch to the normal -f position for at least 5 seconds.

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14. At the reactor control console, ve'rify that the rod posit' ion '

display indicates 00 for the rod just tested. Reset ,the strip chart recorder speed (the 00 indication will appear after the scram ,

switch is returned to normal). ...

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15. , Open charging water valve 113 for the accumulator of the rod just j tested. j
16. Withdraw the control rod just scrammed to its initial position (or to the position specified by the Reactor Engineer if performed in conjunction with Nuclear Performance Evaluation procedure 10.11) .

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17. Record the position 46 drop out, position 36 drop out, position 2,6 '

drop out, and position 06 drop out scram time for the rod just i tested on Attachment "A".

18. Verify the 90% insertion time is within the acceptance criterion of l Technical Specifications Section 3.3.C.3. and Section V. of this  !

procedure. '{>

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19. If more than one rod is to be tested, repeat Steps 8. through 18. l for each control rod to be scram tested. l
20. The information obtained from the recordings-is as follows. l Channel 1 indicates the time the rod scram switch was actuated, .  :

which corresponds to the deenergization of ' the pilot scram valve  !

solenoids. Channel 2 (optional) indicates the time the scram j valves were opened. Channel 3 indicates.the time the rod was fully *

' inserted. The scram time is defined as the-time interval from the  ;

instant the pilot scram valve solenoids -is deenergized to the j instant the_ rod is fully inserted.

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l Procsdure Number 10.9 Date }2 D9k Revision 13 Page 6 'Of 10 Pages '

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21. The core average scram time shall be recored on Attachment "B", as appropriate, and verified that it is in compliance with the Limita-tions of Section V.
22. Verify that the scram times of,any three control rods in any two by two array are less than the limit for the two-by-two array criteria specified in Section V. A.3. If this can be verified,-fechnical ~

Specification requirements as specified in Section V.A.3. have been met. If this cannot be verified, calediate the average insertion times for the three fastest control rods in the two-by-two array containing the slow control rods. Record the average in the middle of the two by two array on Attachment "B" and verify that it is in compliance with the Limitations of Section V. before increasing reactor power or within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

B. Individual Control Rod Computer Scram Times.

Note: Perform the following steps when using the computer for scram timing individual control rods.

1. PerformStepsVII.A.1.throughVII.A.11.ofthisprocedure.[
2. Place the test switch on panel 9-16 timing board to the normal position. ..
3. Determine proper rod identification of the rod to be scram tested.
4. Insert the jumper from the timing board to the selected rod on the scram test" panel.
5. Verify that a jumper from the selected rod is inserted to one of the computer inputs at rear of panel 9-27.
6. Put the test switch on the timing board to test.
7. Scram the rod by actuating the selected rod switch on the scram test panel. Verify that the rod inserts. The rod position window will go blank when the rod is full in.

Note: Do not return the selected rod scram switch to the normal position for at least 5 seconds.

8. Return the scram switch of the selected rod to the normal position and verify that the rod position windows read position 00.

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9. Return the test switch on the timing board to the normal position.
10. Open charging water valve 113 for the accumulator of the rod just tested.
11. Withdraw the control rod just scrammed to its initial position (or i to the position specified by the Reactor Engineer if performed in conjunction with Nuclear Performance Evaluation Procedure 10.11).

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j Prcesdure Number 10.9 Date_[1:523-9t[ Revision 13 Pdge 7 Of 10 Pages l i

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12. Obtain a computer printout and record the required data on Attach- l ment "A" for,the rod just scrammed.

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13. Verify the 90% insertion time is within the acceptance criterion of l Technical Specifications Section 3.3.C.3. and Section V., of this procedure. , l

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14. Repeat Steps VII.B.1. through VII.B.13. for each rod to be tested. l
15. The core average scram time shall be recorded on Attachment "B", as l appropriate, and verified that it is in compliance with the Limita-tions of Section V. I
16. Verify that the scram times of any three control rods in any two by  !

two array are less than_the limit for the two-by-two array criteria l specified in Section V. A.3. If this can be verified. Technical l Specification requirements as specified in Section V.A.3. have been I met. If this cannot be verified, calculate the average insertion I times for the three fastest control. rods in the two-by-two array i containing the slow control rods. Record the average in the, middle l of the two by two array on Attachment "B" and verify that it is in I compliance with the Limitations of Section V. before increasing reactor power or within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />..- '

C. Reactor Scram (20 Control Rod Computer Scram Timer). t

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Note: This portion of this procedure is to be used for evaluation of  !'

control rod scram times following full scrans from power opera-tion.

1. Af ter attaining steady-state operation at a desired rod pattern, i the Reactor Engineer will designate up to 20 control rods to be. j monitored for rod scram times in the event of a full scram from j power.
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2. Insert a patch between the selected control rod location and one of the computer input channels on the scram time matrix board in the rear on panel 9-21. ,
3. Following a full scram from power operation, obtain the computer printout of rod scram times. List each control rod's core location and initial control rod position prior to the scram on the computer printout. Forward the computer printout to* the Reactor Engineer.
4. The Reactor Engineer will evaluate the scram time data and record them on Attachment "B" (refer to Steps VII.B.15. and VII.B.16.

above).

D. MCPR ODYN Computer Model Adjustment.

Note: The ODYN computer model developed by G.E. is now used for the plant pressurization transient analysis. Reference C. provides Proc 2 dure Number 10.9 Date 7 - 2 %- P A/ Revision 13 Page 8 Of 10 Pages L

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information concerning the ODYN model. A statistical analysis of the scram times throughout-a cycle is now necessary. However, only' the scram times corresponding to 20% insertion of control rods are required. The conformance limit scram time and the mean scram time are determined from actual data taken from scrams using the formula presented in Reference C. Ad long as the mean 20% scram time is less than 20% conformance limit scram time, the ODYN Option B analysis is

  • satisfactory. If the mean 20% scram time is greater than 20% conformance limit scram time, a statistical adjustment must be made to MCPR. The following procedure provides the formula for determining the 20% mean scram time, the 20% conformance limit scram time, and the j adjustment to MCPR.

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. The Reactor Engineer will . perform the following steps upon ,

completion of Section VII.A., VII.B., or VII.C. above utilizing Attachment "D". ,

1. The monitored notch position which c.orresponds most closely to 20%

insertion of the rods is notch 36.

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2. The mean scram time, T,y,, for insertion to notch 36 is:

n -

INg.Tg T,y, = i=1 n

EN g ,

i=1 Where:

n = number of surveillance tests performed to date (including BOC) in the cycle; T g = average scram time to notch 36 for surveillance test i; Ng = number of rods tested in surveillance test i.

Calculate and record T,y, in. Step 1.

3. The 20% conformance limit scram time, T , is determined as follows:

B N,- }1/2 T

B

= u + 1.65 . o . :/n

@) .

Where:

u = mean value for statistical scram time distribution to notch 36

= 0.852 seconds; i

Prcesdure Number 10.9 Date- ~]f-l?:3-74/ Revision 13 Page 9 Of 10 Pages

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., Us o = standard deviation of above distribution = 0.060 seconds; Ng = number of rods tested at BOC = 137.

Calculate and record T B in Step 2.

4. If T < to T , the MCPR operating limit is 1.26'for 8 x 8/8 x 8R/P$**x 3R and indicate N/A on Step 4. of Attachment "D". Sign Attachment "D" to indicate completion of scram time analysis.
5. If T >T cross out and indicate N/A on Step 3. of Attachment "D"IEIcomfu,teMCPRasfollows:
a. Calculate a Scram Time Quality Factor (T):

T

r. ave -T B , ,

T -T A B Where: '

TA = Technical Specification , limit-for 20% insertion for notch 36 = 1.10 seconds.

b. Determine new MCPR operating limits from t vs. MCPR Curves.

Technical Specification Figures 3.11.2.b., 3.11.2.c., and 3.11.2.d. and record on Attachment "D".

c. Input new MCPR limits into the process computer.
d. Sign Attachment "D" to indicate the new MCPR limits were input into the process computer and the completion of scram time analysis.

VIII. ATTACHMENTS A. CRD Scram Times Data Sheet.

B. CRD Scram Time Summary Data Sheet.

C. CRD Accumulator Location In Reactor Building 903'.

D. CRD Scram Time Analysis Data Sheets.

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1 Procedure Number 10.9 Date M 7-f Revision 13 Page 10 Of 10 Pages.

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