ML19209C781

Discusses Fluctuation Testing Performed on 790830-31 & 0901.Small Valve Deviations Made Detection Difficult W/Existing Instrumentation Displays.Safety Analysis Rept & Tables Encl

ML19209C781
Person / Time
Site:	Fort Saint Vrain
Issue date:	10/12/1979
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Kuzmycz G Office of Nuclear Reactor Regulation
References
P-79235, NUDOCS 7910180291
Download: ML19209C781 (22)

Text

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16805 Road 19 1/2, Platteville, Colorado 80651 October 12, 1979 Fort St. Vrair Unit No. 1 P-79235 Mr. George Kuzmycz U. S. Nuclear Regulatory Commission Division Proj ect Management Special Projects Washington, D. C.

20555 Dockat No. 50-267 Subj ect : Fluctuation Testing and Revision of RT-500

Reference:

1)

P-79211 2)

P-78137

Dear Mr. Kuzmycz:

As reported in the Reference 1, Cycle 2 fluctuation testing at about 40% and 50% power levels was performed on August 30, 31 and September 1, 1979. A total of four fluctuation avents were recorded on the data systems. Reduction of this data has now been completed and reviewed by both General Atomic Company and Public Service Company of Colorado. Cycle 2 fluctuations have many similar characteristics to those from Cycle 1.

However, Cycle 2 fluctuations were generally more core wide with smaller recorded deviations in both linear nuclear channel readings and in module main steam outlet temperatures.

The maximum linear nuclear channel deviation from the average was 1.5%

(of full power reading) with two events being only 0.5%.

Module main steam outlet temperatures were generally in the 20-30*F range with the maximum peak-to-peak value being about 45'F.

Since the above parameters are used during flucturtion testing to determine when a fluctuation has been initiated and when it has stopped af ter a power reduction, the small value of e c.e deviations made detection difficult with existing instrumentation displays. A total of 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> and 15 minutes were spent in a fluctuation operating mode for the four events. This exceeds the predicted estimate in RT-500F, but was unavoidable because of the changed characteristics of Cycle 2 fluctuations.

We have, therefore, revised RT-500 to (1) include a new defini-tion for fluctuations, (2) revise the time to be spsat in fluctuations, and (3) provide procedures for a portion of one fluctuation period to be conducted with the steam generator module trim valves in manual 1178 127

1. T 7 91018 0 2 cf /

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Mr. George Kuzmycz Page Two October 12, 1979 control. The latter is to determine to what extent trim valve changes which occur during a fluctuation contribute to module main steam temperature deviations. Additionally, modifications in data displays have been implemented to further enhance the ability of the operators and testing personnel to identify a fluctuation with Cycle 2 character-istics:

The revisions outlined above have been incorporated into RT-500, Revision G, a copy of which has been enclosed for your review and information.

It should be noted that the definition for fluctuations has been conservatively changed as follows:

"The plant is defined to be in a fluctuation operating mode when individual nuclear channels exhibit cyclic deviations from the average power equal to or greater than 0.5% peak-to-peak of full power readings not exceeding a 30 minute period."

Table 1 shows a summary of the four Cycle 2 fluctuation events. Note that only the first and marginally the second events constitute a fluctuation by the old definition that the offset be equal to or greater than 1% of the full power reading. The revised definition classifies all four events as fluctuations. Note from Table 1 that the new definition permits detection of a fluctuation event within the first 1/2 hour of the event with improved data displays in the cable room discussed below.

Nuclear Channel deviations of the small magnitude cont 'ned in the revised definition are not readily detectable on an absolute scale even when displayed on a narrow range trend recorder.

Instru-mentation noise and regulating rod movements contribute to identifi-cation dif ficulties. However, the display on a narrow range chart of a nuclear channel minus the average of all six nuclear channels eliminates control rod jogs and permits identification of nuclear channel fluctuation deviations such as those experienced during Cycle 2.

bdifications have been completed which will allow at least three nuclear channels minus the average power to be displayed with a narrow range on the trend recorders in the control room.

The fourth trend recorder will be used to display the outlet temperature of Region 20.

This region has exhibited the largest temperature swings (up to 62*F peak-to-peak) during Cycle 2 fluctuations.

As previously stated, 14 3/4 hours have been spent in a fluctuation operating mode during testing under RT-500, Revision F, for the four Cycle 2 events. This is in addition to the 65 hours7.523148e-4 days <br />0.0181 hours <br />1.074735e-4 weeks <br />2.47325e-5 months <br /> of fluctuations for the 30 events during Cycle 1.

The Cycle 2 1178 128

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Mr. Jeorge Kurmycz Page Three October 12, 1979 fluctuation test plan per RT-500 included provisions to do fluctuation testing at about 60 to 70% power levels. TL2 additional testing including a repeat test at each power level would add four fluctuation events. Assuming an additonal 10 hours1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> are spent in a fluctuation mode while the four additional fluctuation tests are conducted, the total time of fluctuations during Cycle 2 prior to installation of region constraint device would be about 25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />. The total time of fluctuation operation for Cycle 1 plus Cycle 2 is expected to be 90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br />.

Both Cycle 1 and Cycle 2 fluctuations exhibit periods of about 10 minutes. Therefore, a maximum of 540 cycles will have occurred prior 'to installation of the region constraint devices. This is a small fraction of the 10,000 cycles under expected fluctuation load Conditions for graphite components within the core which were analyzed for in Reference 2.

It is anticipated that the actual time of fluctuation operation for the remaining testing will be less than that assumed.

It is our judgement that the changes to RT-500 contained in Revision G, attached, are largely administrative and do not nulify the prior NRC approval to perform fluctuation testing up to 70%

power prior to the installation of the region constraint devices.

It is our plan to perform the additional fluctuation tests the week of October 17, 1979.

Very truly yours, h W kw!: ^h^

Don W. Warembourg

>bnager Nuclear Production D'4W: dkm Attachment jj[g j}g

Tahle 1 Fort St. Vrain Cycle 2 Core Temperature Fluctuation Events tiaximum Maximum Maximum Maximum utfset Cluinnel Peak-to-Peak Peak-to-Peak Peak-to-Deviation 1.inear Channel 1.inear Channel Peak K)dule

% Power (Olt! Definition)

Deviation (New)-

Deviation (New) -

Main Steam Date Time Start

% First 1/2 lir.

% Total Event

• F 8/10/19 1600-2200 40 I I/ 3-1 1.0 1.8 25-35 8/31/79 0318-0830 41 3/4-1 0.7 2.2 35-45 9/01/79 0350-0535 49 1/2 1.1 1.2 30-40 9/01/79 0923-1130 51 t/2 1.0 1.1 20-25 CD O

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RT-500-G GA RT -500 Revision G REF REE REF REQUEST FOR TEST DATE 10/12/79 ISSUED i

REQUESTCR K. Asmussan /W. Simon SYSTEM 12 D

PURPCSE/CBJECT!VE - There are two main objectives of this test:

D 1.

To deter =ine the fluctuation threshold in terms of core e essure drop D

vs flow (power) for cycle 2 operation.

D 2.

To obtain FM data during fluctuations with the revised instrumentation 6

D systems for comparison with cycle 1 data.

C C

DESCRIPTICN CF TEST - With the plant in normal cperation, core orifices D

will be adjusted to achieve a specified core pressure drep.

Load increases D

in ~3*s steps and pulse changes in circulater speed of ~30 will be used cs D

trigger sechanisms to induce fluctuations and :c deter =ine the fluctuation D

thresheld in ter:s of core pressure drop as a function D

of core ficw rate (pewer level). 'ihen a fluctuation occurs, the step D

causing the fluctuation will be repeated to demonstra:e repeatabili y.

D Flue:uatiens will be initiated first at ~cGi power and then a: ~10$ intarvals D

so as to provide a good definitica of the stabili ', threshold line.

Par: 1 D

cf the tes: encespases testing a: < 0$ power.hile Part 2 refers to testing C

at >70% power. For at least one fluctuation, BI data will be obtained

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.with the reg-cd held in a constant position.

E Revi.s ion e incor orates PSC coments on 'Ravision 7 " - ~-- '-- - - -~ '

RMcor::porates NRC comments on Revision t.

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_evision G incorp h es a revised definitio r)increasesthe

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G estimated time spent in a fluctuating made. These revisions are based on experience gained from RT-500F testing at 40% and 50% power.

A.YTICIPATED RESULTS/ ACCEPTANCE CRITERIA. - The test will provide data to D

aid in predicting conditions for stable operation. Additienally, data D

will be obtained which will aid in understanding the flue uation phenc enon D

and for cc parisen with cycle 1 observations.

here are no specific anti-cipated results or acceptance criteria.

REF SCP CR ABSCR.'!AL CONDITIONS SCP 12-04 SCHEOULE RE"UIREME';TS _ __

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limit and the reg ten erit it-c-nu-es so that ev_rn curine t'r -est eavc-e fluctuation ctscrved to date the TccF Sccc lir,its v;ill ret be violat_ed.

(Sec Figure 1.) /,ltreu;5 trere will be a ceriod of tb e tb't **= re' _rrd is disabid and net rest:rcire. to the auto flur I r.c n !."c c-d e n P.*--'t'

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RT-500 Rev. F (CHIC:t k'ITH DCC2ENT N FOR Li*'tST ISSUI)

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GZ5ERAL ATCMIC CCMFANT FCET ST. VRAEi NUCLEAR N A' PUG ST.ATICN SAFETI ANALYSIS REPORT 1.

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3 ASIS FCR SAlZTT E7ALUAI*CN: (Add addi.1onal Sheets i.f Required):

During this test, oceration will be within Tech Scac and dacion 14m4+s The test is performed to investigate the threshold for fluctuations. and althouch they might be encountered, the time at fluctuation would be minimal. Consecuently, any fatigue damage to the core and/or steam cenerators would ba naolicible. Main steam temperature fluctuation limits have been set accordinciv.

In a cM i + 4 n n -

.'hrougnout the test, sufficient margin wi'll be maintained between tha Tach caar

~Iimitandtheregionexittemoeraturessothatevendurinothemostsevere 3 uctuation observed to date the Tech Soec limits will not be violated.

(See Figure 1.) Although there will be a period of time that the ree-ted is disabled and not resconding to the auto flu. (continued on attacked chaaa 11.

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BASIS FOR SAFETY EVALUATION (continued)

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control syste=, test procedures will assure any required rod ru.! backs will take place and will produce the subsequent desired reactor p' er control. Therefore, this test will not adversely affect the integrity of the core or stea generator and will not affect public safety.

Since first being enceuntered en October 31, 1977, fluctuations have been initiated several times in a continuing effer to understand their The power levels at which fluctuations were initiated k ve ranged cause.

D frc: 3 0% to 63's.

A total of about 65 hcurs has been spent in a fluctuating D

ode, which is equivalent to 390 cycles with a peried of ten =imtes.

Although the cause of the fluctuations is not known, there are several reasons for concluding that continued testing is safe. The stal core C

power, ficw, and average te::peratures are relatively stable. An inspection of the top plenu: in Dece=ber 1977 af ter fluctuation testing at power levels between 53% and 68'3 showed it was in good condition. An inspection at tha: ti=e of the control rods in region 34 (which were inserted throughcut the entire period of fluctuation testing) also showed no signs of excessive D

te=perature or i=p c:.

During the 'irst refuelin; cuta;e, eleven blocks D

frc= region 33 were carefully inspected in the PSC hot service facili:y D

and there was no evidence of da= age. An in-core inspection of region 35 D

and its sur cundings with the fuel handling =achine T.V. camera revealed D

no damage or excessive wear to any co=penent. The upper plenu: area D

looked fine; the gaps in the regiens and side reflector sur cunding the r

D cavity left when region 35 was unloaded sere very regular with nc evidence l

L D

of wear or damage. An inspection of the core support blocks in regicns 13 1 D

35 havelikewise revealed no damage.

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Every ele =en: re=oved fre= the core during the refueling of six D

regions has been photographed as has each block in five additional regions D

which were unloaded to permit installation of test asse=blies. Examinations D

of these photographs have revealed no, damage.

D Testing Above 70% Power (Part 2)

D Since fluctuations were first encountered, tests have been con-D ducted under various core conditions.

In large part, these tests were D

designed to gather specific information on what key para =e:er or cc=bina-D tion of para =eters leads to the fluctuations, since this knowledge c:uld D

be instru= ental in understanding their cause. These tests have shown D

fairly conclusively that power level is not by itself a parameter of pri=ary D

importance to the fluctuation threshold, and they have established core D

pressure drop as a key parameter, probably closely related to the cause of D

the flue:uaticns. Another result frc= these tests is that i appears that D

the core pressure drop at which fluctuaticas are produced is higher at D

higher core power levels.

D Differences in fluctuation magnitudes end character have been observed D

in the ~63 fluctuati:ns that were initiated during cycle 1 cperation.

D These differences have been carefully studied and reper:ed extensively.

D No apparent cor elation with power level has been noted, nor has a change y

1178 134

RT-500 G Sheet 3 of 17 D

been observed with time that would indicate increasing fluctuation magni-D tudes or significant differences in character. All of the fluctuation D

testing linits and operating considerations as well as nor=al plant tech-D nical specification limits and SCPs are in effect both below 70% power D

and above 70'e power. Cne exception is the limit on nuclear detector D

fluctuations. This limit is increased from 10*4 at <?O*. power to 20% for D

>70% power. This increase is justified because nuclear channel fluctua-D tions are believed to be due prinarily to a strea=ing effect and are thus D

expected to be nearly proportional to the power (neutron flux) level.

D In this test, fluctuations will be initiated at successively higher power D

levels. The =agnitude and character of the fluctuations at each power D

level will be carefully observed for differences in addition to =enitoring D

the Technical Specification and fluctuation testing limits. Consec.uently, D

testing above 70% power will not affect public safety.

D Ti=e Soent Fluctuating

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D It is anticipated that a total of about 16 fluctuations will be D

initiated during Part 1 of this test (testing <70% power). Total ti=e D

in the fluctuating mode during Par 1 is expected to be no more than G

25 hcurs.

For each of the four power levels at which the fluctuation F

threshold limit will be defined, a first fluctuation will be initiated and F

sustait.ed for a 1-hour period (Step 4B of the Procedure). To verify repeat-F ability, three additional fluctuations.will then be initiated and i==ediately F

halted at each of these power levels (Steps 5, 6 and 7 of the Procedure).

F One-half (1/2) hour in the fluctuating =ede has been allotted for each of the C

F latter three fluctuations. In addition, for one fluctuation during the F

conduct of this RT, the fluctuation will be sustained for one-half (1/2) hour

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'G

' with the reg-rod disabled and all rods held in a constant position and for (1/2)

G

\\ hour with the tris valves in =anual (Part 1, Step 4C of the Procedure).

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G The additional ti=e spent in the fluctuating ode has been increased due to N

G

' experience obtained fro: testing with RT-500F at 40 and 50% power. Cycle 2 1

G fluctuations obtained at those powers exhibited similar characteristics to

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G Cycle 1 except that the linear nuclear channel deviation fro = the average was s

G s= aller. For two of the fluctuation events, they were as small as 0.5%.

Since

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G these para =eters are used to determine when a fluctuation has been initiated and G

when it has ter=inated, the s=all value of the deviation =ade detection difficult.

G To date, a total of 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> and 45 =inutes have been spent in the fluctuation

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G ode and tests still re=ain to be done between 60 and 70% reactor power.

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D During Part 2 of this test (testing at > 70 power), fluctuations =ay be D

initiated about 8 ti=es, with a total time in the fluctuation = ode of s 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

,r-e 4

RT-500G Sheet 4 of 17 PREFACE Revision A accc=plished the following changes:

(1) The Operating Limits Section was redefined to incorporate limits required by the NRC.

(2) The remainder of the previcus limits were redesignated as Operating Considerations.

(3) The equation for core resistance was redefined to better fit observed operating data.

(4) Addendum I was added to deter-mine the fluctuation threshold at 23*. power.

Revision B acccmplished the following changes:

(1) The 10*, limit on a nuclear channel fluctuatien was extended to cover all six channels.

(2) The required instru=entation was increased to have brush recorders for all twelve steam generator module outlet temperatures and all six nuclear channels; the steam generator temperatures will be =enitored both by wide range brush recorders (700*F - 1100*F) and by either narrow range brush recordtrs (100*F range, :ero suppressed) or digital display of fluc-tuation magnituces from the steam generator data acquisition system.

(3) The limit on module main steam te=perature at which testing is sus-pended until authori:ed by PSC canagement is increased from 130*F to 150*F.

(4) In Figure 1, the region temperature missa:ch margin for region 12 is increased to 100*F.

(5) The instruments :o be monitored by the trend recorders are not specified: any four thought to be of most use may be trended.

(6) A two hour waiting period between fluctuation tests is i

i specified.

I

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Revision C accceplished the following changes:

(1) Corrective action is to be taken to stop the fluctuation if a =cdule main steam tem-l perature reaches 1025'F.

(2) Editorial changes were made to the other limits on module =ain steam temperature.

(3) The test team members respon-sible for conducting the test are specified.

(4) The physical location of the data systems to be monitored are specified, as are the respective team members responsible for monitoring them.

(5) Figure 2 of Addendum I has been " cleaned up" and updated to reflect the current actual locatiens for ther:ccouples 3, 4, 5, 7, 19, 23, and 25.

(6) In Figure 1, the region te=perature mismatch sargin on regions 17, 13, 26, and 27 have been increased.

Revision D accomplished the following changes:

(1) D.e detailed test procedure has been rewritten. The nu=ber of anticipated fluctuations and the total time spent in :he fluctuation mode has been reduced. However, the basic test philosophy and the limits during fluctua:icns remain un-changed.

(2) RT-502 (Threshold Testing >70% Pcwer) has been incorporated as Part 2 of this RT.

(3) The objectives of the test have been modified to reflect testing during cycle 2 (for ec=parison with cycle 1) with the e=phasis en gathering data to aid in predicting c:nditions for s:able operation.

(4) Addendum I of RT-500 Revision C has not been repeated here because it was successfully completed during cycle 1 testing.

(5)

A definition of a fluctuation has been included.

(6) There have been numerous editorial changes (changes are denoted by a D in the margin).

Revision E incorporates ::==en:s fr== PSC to delete the detailed crifice adjust: ant procedure, upda:e Da:a Shee: 1 to include all 11:1:s and other

=1:or cc:=en:s as coted in the lef: argin.

1178

,i36 Revision F incorporates cements frc= NRC as noted.

V

-. mp 7

Revision G incorporates a revised definition of a fluctuatien and increases %

the estimated time spent in a fluctuating mode. These revisions are based on I

experience gained from RT-500F testing a 50'; and 60*. power. The increased ti=e is the result of approximately 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> spent in a fluctuation mode during

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co=pletion of the first half of RT-500F.

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RT-500 G DDR ORl8lm i

INTRCDUCTICN D

The collection of data from all cycle 1 core fluctuations indicates a distinct influence of core 1P on the threshold for fluctuations. However, D

the cycle 1 data shows a lot of scatter and fresh fuel has been loaded D

into six regions of the core; therefore, fluctuation threshold testing at D

the beginning of cycle 2 is necessary.

D This RT will determine the fluctuation threshold as i function of

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D core pressure drop for cycle 2 (wi:h a procedure aimed at minimi:ing D

the amount of scatter in the data). The FM Data System now includes D

24 traversable ther:occuples, FCRV displacement probes and magnetometers D

for attempting to monitor core barrel motion, and two instrumented control D

and orificing assemblies having in-core instrument packages. These data D

will be collected during fluctuations to aid in predicting conditions for D

stable operation and in understanding the fluctuation phencmenon.

D The expected :ethods for triggering a fluctuation will be a 3's load D

increase at 3'5 per minute and a pulse change in circula:Or speed sufficien:

D to produce ~ 3 *4 increase in flow. When a fluctuation develops, the steps D

preceding and resulting in the fluctuation will be repeated to demonstrate D

repeatability and :o previde a reasonably accurate determination of :he D

threshold power.

The tes scope includes the determination of the fluctuation D

threshold for at less: three values of core flow resistance.

[u-Testing will be conducted by the coordinated efforts of a test :ea:

consisting of, but not limited to, the following = embers:

1.

PSC Shif Super /isor 2.

PSC Reactor Cperator(s)

D 3.

Test Cecrdinator D

4 Core Perfor=ance Engineer D

5.

Data Systems Engineer F

The NRC will be provided, within.one week, with a su==ary of test results for F

each power level. Included with these results will be notification of any change to F

the procedure as a result of the test results.

OPERATING CONSIDERATIONS In addition to the ner=al plant operating procedures and limitations, the following should be obserted:

1.

The HFJi and MS temperature imbalance between each SG medule and.

C the average for the Icep sh:uld not exceed 30*F (in steady state) or C

the limits given in $CP 12-04 whichever are more restrictive.

In additi:n, the maximum individual module MS steady state tempera-ture should be limited to 995*F.

The pu pose of the 995*F lini:

_is to provide margin en MS temperature when fluctuations occur.

2.

Steady state module helium inle: temperature shall be limited to

(_s 145'F about the mean or :he limits given in SCP 1:-04 whichever are more restrictive.

1178 137

._...RT-500 G

- -~

Sheet 6 of 17 D

3.

In order to minimite the chance of getting into a degraded perfor-

=ance condition during fluctuncions, the maximum region outlet gas e

tc=perature during steady state conditions shall be limited as follows:

From previous fluctuation dtta, it was noted that the folicwing core regions exhibited the most severe tc=perature changes during the C

fluctuation: Regions 1, 2, 3, 4, 5, 6, 7, 9, 12, 20, 33, 34., 35, B

36, and 37.

All of these regions cust be kept at least 60*F, 80*F, B

or 100*F below the allowable temperature limit of LCO 4.1.7 as shown in Figure 1.

All other regions must be kept at least 35*F below the allowable limit.

E NOTE: The margins per Figure 1 are based on cycle 1 experience. When fluctuations are observed in cycle 2, the regions that exhibf t the largest temperature variations may be different. As differences, if any, are observed, Figure 1 will be administratively revised

%A ^- '

m G.

4 The plant is defined to be in a fluctuation operating = ode when G

individual nuclear channel's axhibit cyclic deviations frc= the average G

power equal to or greater than 0.5% peak-to-peak of full power not G

exceeding a 30-minute peri F

5.

Operation and/or testing at power levels >70 should be in accordance D

with the 3-0 startup test program.

F 6.

Throughout the duration of this RT. all plant control syste=s are to be

(

F in auto =atic (except for the one test with the reg-rod in =anual, see s

F Step 4C of the Procedure), and with MS and EF3 te=perature controls set 0

F to a =aximu= of 980 7.

F Note:

The teason for selecting the te=perature setpoint at 980 F vs F

1000 F is to allev =argin for the te=perature swings that l

~ F occur when fluctuations develop.

. LIMITS DURING FLUCTUATION TESTING Test Li=its F

1.

Proposed testing will be conducted within the Technical Specification F

li=its.

F 2.

Throughout the test, the intent will be to =ini=1:e the time spent F

in fluctuation except when necessary to record FM data.

'4 hen fluctu-F ations are present, the following should be observed:

F A te=perature fluctuation of module main steam te=perature F

about its =ean of 110 (20 F total a=plitude) is acceptable F

vith no specific time considerations.

F A te=perature fluctuation of =odule =ain stea= te=perctura F

about its =ean greater than -10 ? (20 F total a=plitude) but

~

F less than -30 F (60 ? total a=plitude) should not exceed one F

hour in duration per event.

1178 138

RT-500 G Sheet 7 of 17 A te=perature fluctuation of =odule =ain stea temperature (F

0 F

about its =ean of 130 F (60 F total amplitude) is cause to F

take i==ediate corrective action by reducing power to stop F

the fluctuations.

F A uni-directional module =ain stea temperature change of 60 F F

(excluding the average co=ponent of intentional stea te=perature F

changes) is cause to take i==ediate corrective action by reducing F

power to stop the fluctuations.

F A =odule =ain stea te=perature of 1025 F is cause to take i==edi-F ate corrective action by reducing power to stop the fluctuation.

F A primary coolant activity increase greater than a factor of 25%

F but less than a factor of 5 over the prior equilibriu= value for that power level is cause to take i==ediate corrective action by e

F reducing power to stop the fluctuations.

F 3.

A limit of 110% of full power range on any nuclear channel will be F

=aintained.

9 F

4 The helium purification syste= will be in service during all testing.

F 5.

An increase in pri=ary coolant activity levels greater than a factor of F

five (5) over prior equilibrium values for that power level during any F

fluctuation test will be cause for terminating the testing and proceeding F

with an orderly plant shutdown.

Corrective Action F

1.

If any of the established li=1ts or conditions outlined in ite=s 2 F

through 4 above are exceeded during a fluctuation test, the test will

,F be ter=inated, and further plant testing in the fluctuating =ede will F

be suspended until specifically authorized by PSC =anage=ent.

F 2.

If any of the following conditions are exceeded, i==ediate action will F

be taken to terminate the fluctuation test and further testing in F

fluctuation mode will be suspended until authorization to proceed F

is obtained fro = the Ce==ission:

y a) Technical Specification li=its are exceeded y

b) An increase in pri=ary coolant activity levels greater than F

a factor of five (5) over prior equilibrium values for that F

power level.

F c) A temperature change of module =ain stea= te=perature of F

150 F relative to the initial steady state te=perature and F

axclusive of ta=perature change due to load changes F

d) A =odule =ain ste*7 te=perature which exceeds 1075 F.

F 3.

If inadvertent fluctuations are observed (see page 6 for the definition

(,-

F of a fluctuation) in normal operation, corrective action will be taken 1178 139

RT-500 G Ip [

[

I

.g Sheet 8 of 17

. F to ter=inate the fluctuation, and PSC management authorization will F

be required prior to returning to a power level that would approach F

that level that the inadvertent flucturtions were observed.

INSTRB EiTATION/ DATA SYSTBt3 Through the duration of this :?st, the following data systems shall D

be opera:ing and personnel should be present for =onitoring:

C 1.

Brush recorders (located in the auxiliary control room) with all D

steam generator =cdule main steam outlet temperatures and nuclear C

channels. A data system engineer will be present to =enitor the recorders.

Both wide range brush recorders (700*F - 1100*F) and either narrow rsnge brush recorders (100*F, :ero suppressed) or digital display by the steam generator data acquisition system will be D

available to monitor the steam generator =cdule =ain steam outlet temperatures.

C 2.

Data logger (located in the centrol room). The core performance engineer will be present to =onitor the core temperature limitang conditions for operation.

C 3.

The primary coolant activity =enitor (located in the centrol roem).

D 4

FM data,cquisition system.

If any of the above systems beccees inoperable, testing shall be halted until the syste= is reinstated.

If fluctuaticas are encounte ed when any of these systems is incperable, core power shbuld be. educed until the fluctuations cease.

D During power increases or pulsed circulater speed changes and f:r a D

period o# 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> (power increase) or -1 hour (cir:ulator speed paisel D

following either of :hese system ehnges. the following da:a syst:-

and data taking frequencies are desired:

1.

Data logger on a fast sample rate (13 seconds or less) 2.

Sceam generator Fox II cc:puter on a fast sample rate ('S seccnds) 3.

Model verifica:icn ec=puter 4.

FM data acquisi: ion system D

S.

Brush recorders At perieds during the test when the initial c:nditiens for a flue-tuation test are being established (orifi:e adjustments, flow /pewer changes),

the following data sys' ems and data :sking frecuencies are desired.

c 1.

Data logger en a sample rate of 2 minutes or fas:er

(-

2.

Steam generator Fox II cc=puter on a sa=ple rate of 13 see:nds or faster 1178 140

RT-500 G Sheet 9 of 17 3.

Model verification cceputer D

4 FM data accuisition system D

5.

Brush recorders D

The traversable ther=occuples are to be positioned per RT-524 PART 1: TESTING AT 9 0% PCWER 7

Initial Conditions I

l F

1.

Plant at approx 1=ately 40%. power.

2.

The orifices are to be adjusted such that the region exit tempera-tures and stels generator inlet te=peratures are ressenably balanced D

per normal procedures and per the Coerating C:nsiderations section D

of this RT.

Procedure D

1.

The objective of :his tes: is to develop a core pressure drop vs D

core flow rate (or power) stability threshold line. Thus it is t

f' D

desired to initiate fluctuations at three or more values of core

\\--

D flow ra:e. This will be done by crificing the core to different l

D flow resistances. Depending on the core flow rate at which fluc-D-

tuations are initiated in the first test. higher or lower values D

of core resistance may be selected. To generate a reasonably gccc D

stability :hreshold line it is desired to initia:e flue:uations a:

- D a lowest power level of abou 4C*i :: 50*a and at abcu: every 10*4 0

increase in power thereafter.

D NCTES:

1.

Each time fluctuations are initiated, Oata Sheet 1 zus:

D he ce=pleted.

D 2.

The cs: effective means of halting fluctuati:ns is by D

pcwer reduction.

Experience has shown tha: to hal: 2 D

fluctuatien thd pcwer may have to be reduced by 5'. :o 1C*4 3

below the power level wnich produced the fluctuation.

D 3.

Wait at leas: '. / hcur to reach ther:a1 ecuilibrium D

prior to perfor=ing any flucrua:i n :est, wai hours D

after attempting to ini:ia:e a flucruation by a lead D

increase before ::ntinuing, wai: I hour after a::e pting D

to initiate a fluctuati:n by a pulse change in circula:::

D sp,eed before continuing.

1178 i41

/

w

eet 10 of 17

'D 2.

For the first test configuration, adjust the core crifices i.n a series E

of steps using the procedre supolied by the test : crdinator as a guide

~D to obtain an average core pressure drop of 2.3 :si. C re resistance c0rres-O pending ta this c:re pressure dre: and core flew ra:a : ay be calculated by:

2.'O 1013 gP Sleasured Pressure Resistance

=

(T.

. 460) ricw-o-

in where 1P =easured is the =eas=ed core pressure d: p in psi (ite: 71 in DF 76)

Fressure is the circula::: inle: helius press =e in psi (ite:

9 in DF 76)

Flow is the :ctal circula:or flow in 1b=/hr (ite: 72 in DF 76)

T is the circula:or inle te=rerat=e in degrees Fahrenheit (k9erageofite=s1and2inCF'76)

Verify that the region cutlet gas te=peratres have adecuate =argin frc= LCD 4.1.7 per Figure 1 and :ha: the S/G =cdule te=pera:ures are within the Opera:ing Li=i:s Sectica of this RT before preceeding.

D 3.

Begin a series of power rises by increasing :=bine lead at 3'4 per D

=inute in incre= ental load changes of M ( 9 We). Cen-inue the D

incre= ental load increases until fluctuatiens develop r a plan D

lisi: is reached.

Frics to each incre=en:21 lead increase, adjust orifices as necessary :s balahce region cutle: gas te=peratures and

=edule inle: gas :e:peratures.

!n addition, adjus: the reg-red position ace:rding to no.a1 operations practice.

D 4.

When fluctuations develop, there are three basic sets of data :: btain:

A.

It is desirable to obtain Dt data during the nset ef all fluc-tua:icns.

B.

For ene fluctuation with each c:re ficw resistance, obtain Di da:a for one hour during the fluctuations.

7.e operating li=its stated in this RT =ust be adhered to during :he ene-hour pert:d.

F C.

For one of the fluctuations described in Step 4B, it is desirable F

to obtain FM data for an additional 1/2 hour, with the reg-rod E

disabled and all rods held in a constant position. Attach =ent I defines the procedure for disabling the reg-red.

The operating 11=its stated in this RT =ust be adhered to during fluctuc,tions.

M G

For one of the fluctuations described in Step l.3, it is desirable to ob-G tain F" data for an additional 1/2 hour with the stea= generator =cdule tri:

C valves in =anual control -- (in a fixed posi:1on). During this fluctuation G

period, the operating limits stated in this RT cust be adhered to.

At the G

(

end of this 1/2 hour the tri= valves will be returned to =anual control.

~.

C The Core Ferfor=ance Engineer will coordinate which particular fluctu-C ations will be monitored per ite=s 3 and C above.

1178 142

RT-500 c Sheet 11 of 17 D

5.

Tor each fluctuation encountered, repeat the step preceding the flue-F tuation and, if fluctuations are not encountered, that step which D

caused the fluctuation. For example, if fluctuations are encountered D.

during a power rise from 50% to 53% power, return to 47% power and F

repeat the 47% to 50% power rise. If no fluctuations occur, then D

repeat the 50% to 53% power rise.

D 6.

When a fluctuation threshold has been defined per steps 2 - 4, return D

to the highest power level for which a fluctuation was not initiated D

(474 in the above example). Perform Part II of RT-499, :ne circulat:r D

speed pulse test, where the primary coolant flew is increased by D

~3%, held at the higher value for a short dura:icn ( 10 seconds) and D

returne:i to its initial level.

If fluctuations are not initiated, D

increase power by 3', at 1/2'4/sinute 2.,4 repeat Par: II of RT-499, the D

circulator speed pulse test. Continue until fluctua: ions are encountered D

or until a power level 9', above the =aximum frcs step 4 is achieved D

(until 60's in the above exa=ple).

D 7.

Repeat the circulator speed pulse test (Part II of RT-499) for the F

step preceding the fluctuation and, if fluctuations are not F

encountered, that step which caused the fluctuation.

F 8.

The next test power leve. Jepends on the power level at which fluctu-F ations were encountered in Step 5 above. The objective is to initiate F

fluctuations at power levels approxisstely 10% apart; that is, at F

about 40%, 507., 60% and 707. power.

For the selected new power level g

(

D the next value of core resistance can be calculated frc= the conditions D

which initiated the preceding fluctuation as follows:

?*

Y aI l

D where R s

usismee 6 de puedng test OLD F

F s

ecm w rate c

puce

.g es Step O OLD F

F is the flow rate corresponding to the power level where F

th3nex fluctuation is desired.

D 9.

The starting point for the nex test is with the core crificed :: achieve the F

new core resistance, Rqw, per the ecuatien given in step 2, and wi:5 a core D

pressure drop 10*, - 20', below tha: at which the preceding fluctur.: ion was ini-D tiated. In ge::ing to the new starting peint, i is desired :: keep the c:re D

pressure drop at or below the value at whi:h the fl;;:uation test will be D

started to preven: inatter:en fla::uati:ns. To do this it is sug;;ested that:

D A.

If R3g > Egg, reduce ficw before closing Orifices.

D 3.

If g.g < Rgg3, open cMas Mm k.cnasW h

(

1178 143

RT-500G Sheet 12 of 17 D

10.

Repeat steps 3 - 7 to obtain data for at least 3 values of core re-D sistance. To generate a reasonably accurate stability threshold, D

fluctuatin.3 should be initiated at a lowest power level of about D

40 - 50% and at increments of 10% power above this initial level.

D Depending upon the effect of refueling on the fluctuation threshold, D

it say be necessary to vary attemperation ficw (core P/F), region D

outlet te=perature mismatches, or partially insert control rods (power D

flattening) in order to de=enstrate the threshold at high power D

levels. Any or all of these operations may be used as permitted by F

SOPS and * :hnical Specifications. Caution should be exercised to

.F

=aintain the region temperature margins for L.C.O. 4.1.7 given in F

Figure 1 and to not violats the core ther=al safety li=it on core F

power / flow ratio (S.L. 3.1, Figure 3.1-2).

D If the pulse change in circulater speed test fails as a " trigger" D

for fluctuations for two values of core resistance, then it is not D

necessary to continue atte=pting to initiate fluctuations via this D

mechanism.

D Part 2: Testing at >7C's Power D

From an ini:ial steady-state condition of '70% power, the core power D

will be increased slowly (1/2% per minute) to ~73's and stabili:cd.

If no D

fluctuations occur, pcwer will be reduced to 70*5, stable operation achieved, D

and a pulse change in circulator speed will be employed to attemp: to D

initiate flue:ua:icns.

If fluctuations do not develop, a 3's load increase D

a. 3's per minute will be effected to attemp: to trigger fluctuations.

fl D

This process of slow power increases, :irculator speed pulses, and then

,-m D

rapid power increases of 3's will be continued until fluctus:icns are en-D countered or atil 100's power or a plant limit is encountered.

If fluc-D tuations occur, data will be recorded for a sher: period of time and the

~

D step which initiated the fluctuation will be repeated to establish repro-D ducibility of the enset of fluctuations.

D Initial Conditions F

1.

Plant at approximately 70% power.

D 2.

The orifices'are to be adjusted such that the region exit temperatures D

and steam generator inlet temperatures are reasonably balanced per

,D nor:21 procedures and per the 0:eratine Considera:icas section of D

this RT.

D Procedure D

1.

The objective of this test is to extend the core pressure drop vs D

core flew rate (or power) stabili:y threshold line developed in D

Part 1.

D NOTES:

1.

Prior to each incremental lead increase, adjust orifices as y

D necessary to balance region outle: gas temperatures and i

D

odule gas temperatures.

In addition, adjus: the reg-rod D

7ositien according to normal operations practice.

1178 144

RT-500 C Sheet 13 of 17 D

2.

The most effective means of halting a fluctuation is by D

power reduction. Experience has shown that to halt a D

fluctuation the power may have to be reduced to 5*. to 10%

D below the power level which produced the fluctuation.

D 3.

Each time a fluctuation is initiated, Data Sheet 1 must D

be completed.

D 4.

Wait at least 1/2 hour to reach ther=al equilibrius D

prior to performing any fluctuation test, wait 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> D

after atte=pting to initiate a fluctuation by a load D

increase before continuing, wait I hour after attempting D

to initiate a fluctuatien by a pulse change in circulater D

speed before continuing.

D 2.

Foz the first test configuration, adjust the core orifices in a series E-of -teps using the procedure supplied by the test coordinator as a guide D

to octain an average core pressure drop at least 10% below the threshold D

t.,P detemined in Part i for 70% power. The core resistance correscondinq l

D to this core pressure crop and core flow rate may be calculated by the I

D equation given in Part 1 precedure step 2.

t D

If the core orifices are opened as :uch as possible, the sain steam tes-D perature may be reduced to 40*F below the rehea: temperature se: point, D

core control rods may be partially inserted (

flatten the power distri-D bution and thereby per=i: further :pening of orifices), or attemperation D

flow say be increased within the limits of SCPs and Technical Specifications D

to further reduce the core pressure drop.

D Verify that the region outlet gas te peratures have adequate margin D

from LCD 4.1.7 per Figure 1 and tha: the S/G odule temperatures are D

within the Operating Limits Section of this RT before proceeding to D

the next crifice changes.

D 3.

Increase power by '3's ('9 MWe) at 1/2'a per =inute.

If fluctuations D

do develop, go to step 6.

If fluctuations are not initiated, decrease D

power ty '3% to achieve initial c,onditions once again.

D 4

Perform Part II of RT-499, the circulator speed pulse test, where the D

primary coolant flow is increased by '3'4, held at the higher value for D

a short duration ('10 seconds) and returned to its initial level.

If D

fluctuations develop, go to step 6.

D 5.

If fluctuations are not initiated by step 4, increase power by 3'e at 0

35. per minute. If fluctuations develop, go to step 6.

If fluctuations D

do not develop, repeat steps 3 through 3 starting at the new power level D

('3*6 above the preceding power level). Continue with successively higher D

power levels until fluctuations do develop or until 100'4 power or a D

plant limit is encountered.

D 6.

h' hen fluctuations develop, there are two basic sets of data to obtain:

D A.

It is desirable to obtain FM data during the onset of all fluctuati ns.

t D

B.

For one fluctuatien with each core flow resistance, obtain FM

(

D data for one hour during the fluctuations. The operating limits D

stated in this RT ust be adhered to during the one-hcur pericd.

1178 145

RT-500 G

~

Sheet 14 of 17 D

The Core Performance Engineer will coordinate which particular fluc-rustions will be monitored per item B above.

D D

7.

For each fluctuation encountered, repea: the step (load increase or D

circulator speed pulse change) preceding the fluctuation and if no fluctu-F ations occur, that step which caused the fluctuation,, For example, if F

fluctuations are encountered during a power rise from 73% to 76% power, re-F turn to 70% power and repeat the 70% to 73% power rise, then if no F

fluctuations occur, repeat the 73% to 76% power rise.

D Similarly, if the circulator speed pulse changes initiated fluctua-D tions, then repeat the circulator speed pulse tes (Part II of RT-499)

D for the step preceding the fluctuation and that step which caused D

the flue:uation.

D 8.

After de enstrating repeatability, reduce power and re-establish D

a stable plant configuration.

If fluctuations were first initiated D

by the 1/ 'a per =inute lead increase (step 3), then establish the D

initial conditions preceding initiation of fluctuations and perfor= the D

circulator speed pulse test, step 4.

If fluctuations were first D

initiated by the pulse change in circulator speed (step 4), then D

establish ini:i'al conditions preceding initiation of flucruations and D

effect a 3'.

Icad increase a: 3'5 per minute, i.e., step 3.

If fluc-D tuatiens were first initiated by :he 3'a per =inute lead increase D

(step 5), proceed to step 9.

D 9.

The next starting point is with a primary flow rate (power level)

((-

D sa=e core pressure drop. This may be achieved as before, by cpening D

5% - 10*a above that of the preceding starting point but with the D

the arifices to a new value of core resistance.

D ~

Partial rod insertion may be e= ployed to permit further opening of D

orifices and/or the main steam temperature se: poin: may be reduced to D

40*F below the rehea: temperature se: point to reduce core pressure D

drop.

D To guard against inadvertent fluctuations, the orifices should be D

cpened before increasing flow.

D 10.

Repeat steps 3 - 5, at successively higher power levels, until 100%

D pcwer is reached or until a plant limit is enecuntered.

1i78 i46

RT-500 G Sheet 15,f 17 C

t.

C 1.-(.,

n. g. s o

n M$

n

[O b

~

n g

n Ar.

-ui.'

y~'

G15 35*

x n

)b s

g'O 4CO bc

.c t.-$

g

/q"n ) c, s,,

[, C n

35 a

C 35 0

c., v i

s /--

[O A

,, ( O.)

n u

g.y5

~ C.J es

)

n 3

3)

>(

3" J :.

s is f

!,Q C0

/'

r,,

s., %gK re n.

i e

3:.

'.a naDD n

39 3

)

u G-t-3 n

4g 55 5[

t,1- ?.

4 e

.. B-st.

62.s

\\.

a+s m q. 1.'. f sp a a g %.' c o k w a s %.

(~i.so.n..,.,a/.u-m.,

r e

(new fi;.:re in Revision 3)

If78 14/

RT-500 G Sheet 16 of 17 NITACFJ O T I

l l

REG-RCD INFLUENCE TE3T D

The purpose of this test is to determine if taking the reg-rod out D

of auto will reduce -he a=plitude of the fluctuations and to obtain data D

from the cut-of-core and in-core nuclear channels which are responding to l

D the influence of the fluctuation phenc=enen alone, withou: the c0= plicating D

effect of reg rod =otion influencing the signals. The procedure is as D

follows:

1.

After a fluctuation has developed, monitor the a:plitude of the

=odule MS te=perature fluctuation to verify tha: the Cperating Limits of this RT are met.

Previous experience with fluctuations indicates that the a=plitude may be reduced by slowly reducing power and thus allow a lenger':i=e in fluctuations.

2.

Disable the ability of the flux centroller to move the reg-rod by placing the reneat te=perature c:n roller in manual and then rotating the regulating red selector switch (HS-1213) :o the CFF position.

This per=its the automatic flux control to initiate a rod runback if needed as a result of any ::ansient during this test.

If necessary, manually position the reg-red to the average position that existed prior to disabling the auto =atic centrol feature. This step is desirable in order to maintain a constant value for total reactor power and average core :e:perature.

CAUTION:

If a runback occurs, the rehea: tercerature centroller should be nulled cut and eturned to aut:natic anc H3-1213 returnec to the il cosition as soon as 00ssible.

D 3.

Wait a period of appr0ximately 30 minutes to deter =ine the effect on fluctuations. Control rec = : fend recorders and brush recorders are to be used for this purpose. Return the reg-red to auto by return-ing MS-121S to the *1 position, null out rehea :e:perature controller, and return it to automatic.

!b l4h

I RT-500 c l

Sheet 17 of 17 l

(Completely Revised DATA SHEET I by Rev. E)

C.

Complete this data sheet if fluctuations were encountered. This data sheet is to certify that test limits were not exceeded.

A.

If any of the folicwing limits are exceeded, testing must be stocceo unt11 further autnor1:ed cv PSC Management.

Limit 1.

Were OPERATING CONSIDERATIONS 1,233 met? YES

/NO N/A 2.

Time /Date fluctuation started N/A 3.

Power Level at start of fluctuation N/A 1 nour 4.

Time /Date scwer reduced 5.

Time /Date fluctuation stopped N/A 6.

Power Level when fluctuation stopped N/A 7.

Maximum fluctuation en Nuclear Channel #

N/A

)

Peak Magnitude r

7 8.

Maximum fluctuation of Loop I MS Temp Module #

N/A Fluctuation Magnitude c0*F P-P Hottest Module !

'F 1025'F 9.

Maximum Fluctuation of Loop II MS Temp Module #

N/A Fluctuation Magnitude 60*F P-P Hottest Module #

"F 1025'F

10. Equilibrium Value of Primary Coolant Activity for power level of test N/A

11. Maximum Value of Primary Ccolant Activity During 25% increase test Qcfor

12. Were Data Systems in service? YES

/NO Recuirec for

13. Was a purification train in service? YES

/NO sesting

~

5.

Fcr any of the followinc, testinc must be stoceed and recerted to tne NRC:

1.

Any Technical Specification exceeded? YES

/ NO 2.

Any MS Temperature Fluctuatien > 150*?- YES

/ NO 3.

Primary Ccolant Activity >5 times normal? YES

/ NO This requires ". i = ediate orderly shutdown.

1l78 149 L

PSC SHIF SUPERV!SOR Signa ture/ Cate TEST CCCFOINATOR

$1gnature/Cate