ML20210B179

Suppl 1 to Susquehanna Unit 2 Cycle 2 Stability Test Results

ML20210B179
Person / Time
Site:	Susquehanna
Issue date:	01/28/1987
From:	Morgan J, Patten T, Williamson H SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER
To:
Shared Package
ML17146A701	List: ML20210B179
References
XN-NF-86-90-S01, XN-NF-86-90-S1, NUDOCS 8702090093
Download: ML20210B179 (20)

Text

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X \\-N =-86-90

,1 SU33 _EV E\\~~ 1 I

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SUSQUEHAN \\A U\\

2 CYC_E 2 l.

S-A3l_l-Y ~~EST R ESU _- S I

I JA\\UARY 1987 I

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RICH _A\\ J, WA 99352 i

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EXXON N UCLEAR COMPANY, INC.

I p=:88=8888se, PDR I

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lI XN-NF-86-90 Supplement 1 Issue Date: 1/28/87 I

l SUSQUEHANNA UNIT 2 CYCLE 2 STABILITY TEST RESULTS Contributors:

K. D. Hartley I

S. W. Jones I

D. W. Pruitt %g86 L. A. Nielsen I

Approved By:

v., b '

/~44~ f7 ww H. E. Williamson, Manager Date Licensing and Safety Engineering I

Approved By:

(/ AMEL/

./ 6/f7 T. W. Patten, Manager date i

Neutronics and Fuel Management Approved By:

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'/8/[

t D

, /1/// /

J. N. Mor an, Manager

/ Date Customer ervice Engi ering Approved By:

d W c./37 e

G. L. Ritter, Manager

/

Date Fuel Engineering and Technical Services I

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ERON \\UC A 1COV 3A\\Y \\C.

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NUCLEAR REGULATORY CO5thflSSION REPORT DISCLAINTER INIPORTANT NOTICE REGARDING CONTENTS AND USE OF TIIIS DOCUNIENT I

PLEASE READ CAREFULLY This technical report was derived through research and development programs sponsored by Exxon Nuclear Company. Inc. It is being submitted by Exxon Nuclear to the US Nuclear Regulatory Commission as part of a technical contribution to facilitate safety analyses by licensees of the U.S.

Nuclear Regulatory Commission which utilize Exxon Nuclear fabricated reload fuct or other technical services provided by Exxon Nuc! car for light water power reactors and it is true and correct to the best of Exxon Nuclear's knowledge,information,and belief. The information contained herein may be used by the U.S. Nuclear Regulatory Commission in its review of this report, and under the terms of the respective agreements, by licensees or applicants before the U1 Nuclear Regulatory Commission which are customers of Exxon Nuclear in their demonstration of compliance with the U.S. Nuclear Regulatory Commission's regulations.

Exxon Nuclear's warranties and representations concerning the subject matter of this document are those set forth in the agreement between Exxon Nuclest and the customer to which this document is issued. Accordingly, except as otherwise expressly provided in such agreement, neither Exxon Nuclear nor any person acting on its behalf:

A.

Makes any warranty, or representation express or implied, with respect to the accuracy,compacteness.or usefulness of the information contained in this document, or that the use of any information, apparatus, method, or process disclosed in this document will not infringe privately owned rights.or B.

Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method, or process disclosed in this documen t.

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' XN-NF-86-90 Supplement 1 TABLE OF CONTENTS I

Section Pane

1.0 INTRODUCTION

1 2.0

SUMMARY

2 3.0 TEST DESCRIPTION AND RESULTS.....

3 1

3.1 Two-Loop Stability Test.........

3 3.2 Single Loop Stability Test......

5 4.0 COTRAN AND COTRANSA-2 ANALYSES...............

10 4.1 COTRAN Stability Analyses...................

10 4.2 COTRANSA-2 Stability Analyses..................

11

5.0 CONCLUSION

13 8

6.0 REFERENCES

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I XN-NF-86-90 Supplement 1 LIST OF TABLES l

Table g

3.1 Recorded Signals Two-Loop Test...................

6 3.2 Recorded Signals Single Loop Test......

7 4.1 COTRAN and COTRANSA-2 Calculated Decay Ratios.

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I LIST OF FIGURES I

Firure g

3.1 SSES Unit 2, Cycle 2 Core Loading Pattern.......

8 3.2 Core Power vs. Core Flow.....

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1 XN-NF-86-90 J

Supplement 1

1.0 INTRODUCTION

e lL As part of the reload licensing process in support of Susquehanna SES Unit M

2 Cycle 2 operation, PP&L committed to perform startup testing designed to L

demonstrate stable reactor operation with Exxon Nuclear Company (ENC) 9x9

{

fuel.

This commitment was required by the NRC since the reload constituted the first reload (42% of the core) of 9x9 fuel into a U.S.

BWR-4 reactor.

L The test program involved the independent collection of neutron noise measurements by PP&L and Oak Ridge National Laboratory (ORNL), the latter

\\

r under contract with the NRC.

Two operating state points were chosen for the data collection:

one at a point close to the operating condition at which the baseline noise level is measured per the Technical Specifications, and one within the " detect and suppress" region of the

^

power / flow map during single loop operation.

The actual test conditions were utilized by ENC to perfoun post-test stability calculations using COTRAN (References 1,2) and COTRANSA-2 (Reference 3).

ENC also used the acquired noise data to determine decay ratios using the ORNL algorithm (Reference 4).

I The following results are presented in this report:

o ENC COTRAN stability calculations o ENC COTRANSA-2 stability calculations o Measured decay ratio determinations by ENC using the ORNL algorithm.

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L 2

XN-NF-86-90 f

Supplement 1 L

2.0

SUMMARY

Results from Susquehanna SES Unit 2 reactor APRM noise monitoring, COTRAN and COTRANSA-2 calculations, and measured decay ratios based on noise i

L analysis confirm that the Unit 2 core, which contains 324 ENC 9x9 reload

[

fuel assemblies (42% of core; balance 8x8 fuel), is stable for two-loop and single loop operation.

Results from the COTRAN and COTRANSA-2 decay F

ratio calculations indicate core decay ratios less than or equal to 0.33 for both two-loop and single loop operation at the test conditions.

These results are consistent with the measured decay ratios determined by a

noise analysis of the APRM signals.

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3 XN-NF-86-90 Supplement 1 3.0 TEST DESCRIPTION AND RESULTS The two-loop stability test at Susquehanna SES Unit 2 was performed during Cycle 2 startup on November 2, 1986.

The single loop stability test was performed a week later on November 8, 1986.

Prior to the tests, the plant was maneuvered to the power / flow conditions required for the test (see Figure 3.2).

At the start of the test, the APRMs and LPRMs were monitored to assure unusual oscillations (compared to Cycle 1 operation) did not exist.

The stability test procedure consisted of data collection during steady state operation.

The ENC F0WERPLEX@ CMSS was used to record plant parameters that were necessary to perform post-test stability calculations.

APRM and LPRM data were recorded at both test conditions with the PP&L GETARS system.

Each GETARS signal was collected at a frequency of 30 samples per second.

ORNL recording equipment was used during the two-loop stability test but was not set up for the single loop test.

All LPRM signals monitored and recorded during the tests were adj acent to two 9x9 fuel assemblies.

The Cycle 2 core loading map, which shows the location of the LPRMs and 9x9 assemblies, is presented in Figure 3.1.

I 3.1 Two-Looo Stability Test The plant was maneuvered to the 59.7% power /46.7% core flow condition, which is very close to the 100% equilibrium xenon rod line at the SIL 380 (Reference 5) boundary (45% flow) for the two-loop stability test.

Figure 3.2 shows the test locations on the Susquehanna power flow map.

By the end of the 2-1/2 hour data recording period, power decreased approximately l

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4 XN-NF-86-90 Supplement 1 I

2% due to a xenon increase.

No unusual APRM or LPRM oscillations, as compared to Cycle 1 operation, were observed.

Data was recorded on three different devices during the two-loop test; the ORNL FM recorder, the PP&L GETARS computer, and the ORNL portable computer.

Table 3.1 shows which signals were recorded by these devices.

In addition to the recorded noise data, the ENC POWERPLEXe CMSS was used I

to record plant parameters that were necessary to perform post-test stability calculations.

The APRM-A signal data were processed by the ORNL portable computer at the time of the test.

The data were recorded by the portable computer at the rate of 5 samples /sec (each sample contained the average of 20 signals) and blocked into 50 second increments.

The Power Spectral Density (PSD) was determined for each data increment as the computer continued to sample data.

The Power Spectral Densities for each data block were averaged together for the test period.

The final Power Spectral Density was then saved for the actual determination of the decay ratio. This final PSD was a composite of all the data acquired during the first 47 minutes of the I

test (12:09 to 12 : 56 p.m. ).

The " measured" decay ratio recorded by the ORNL portable computer was 0.396.

Subsequent to the

test, PP&L supplied the GETARS data to ENC for determination of a " measured" decay ratio.

Analysis of the GETARS recorded APRM noise signals for the two-loop stability test was performed I

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XN-NF-86-90 Supplement 1 at ENC using the ORNL decay ratio algorithm.

Results of the analysis indicate a " measured" decay ratio of 0.33 with a standard deviation of p

0.064.

L 3.2 Single Looo Stability Test The single loop stability test at Susquehanna Unit 2 was performed at a

F L

flow of 44s and power of 55%, within the boundary of the " detect and suppress" operating region (Figure 3.2).

The methodology and data recorded were similar to the data recorded for the two-loop stability test except that equipment from ORNL was not installed for this test.

The LPRM and APRM signals recorded during the test on the GETARS computer are shown in Table 3.2.

Subsequent to the

test, PP&L supplied the GETARS data to ENC for determination of a " measured" decay ratio.

The noise analysis of the single loop GETARS recorded data was performed at ENC using the ORNL decay ratio algorithm (Reference 4).

Results of the analysis indicate a decay ratio of 0.30 with a 0.064 standard deviation for the single loop stability test.

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6 XN-NF-86-90 Supplement 1 IL F

TABLE 3.1 RECORDED SIGNALS TWO-LOOP TEST u

FM GETARs Portable Signal Recorder Computer Comouter APRM-A x

x x

4 B

x L

c x

D x

E x

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F x

LPRM 40-25 C x

24-49 D x

48-17 A x

24-49 A x

16-17 B x

24-49 B x

x x

48-17 C x

24-49 C x

Narrow Range Pressure x

x Total Core Flow x

x lI I

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7 XN-NF-86-90 F'

Supplement 1 L

F 1

L TABLE 3.2 RECORDED SIGNALS SINGLE LOOP TEST r

L GETARs sienal Comouter APRM-A x

B x

C x

D x

E x

{

F x

LPRM 32-49 B x

32-09 C x

L 16-49 A x

32-09 D x

32-49 D x

f 32-09 A x

16-49 C x

32-09 B x

L Narrow Range Pressure x

Total Core Flow x

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XN-NF-86-90 SSES UNIT 2, CYCLE 2 CORE LOADING PATTERN g

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i GE 000204060810 12 '4 16 18 20 22 24 26283032 34363840 42 44 46485052 54565860 0 MEDIUM BUNDLE (1.76) G HIGH ENR. BUNDLE (2.19) 8 ENC 9X9 BUNDLE (3.31)

FIGURE 3.1 lI

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XN-NF-86-90 Supplement 1 FIGURE 3.2 CORE POWER VS. CORE FLOW I

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TWO FUMP TEST POINT g

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NOTES APRM UNE BASES ON SSES DESKW SPEQRC I

CORE FLOW VS 30 REQRC. DRIVE FLOW WR = REQRC DRIVE FLOW PERCENT.

20 CIRC +

2 PUMP MIN. FLOW I

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0 10 20 30 40 50 80 70 80 90 100 1

CORE FLOW,% RATED I

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10 XN-NF-86-90 Supplement 1 4.0 COTRAN AND COTRANSA-2 ANALYSES y

l" Core decay ratios for the two test conditions were calculated with

}

E COTRAN a two dimensional reactor kinetics program with reactivity u

feedbacks for BUR core analysis and COTRANSA-2 a two-dimensional reactor kinetics program which consists of the core coupled with the recirculation loops. These analyses and results are discussed below.

4.1 C,0TRAN Stability Analyses The approved ENC COTRAN methodology, described in References 1 and 2 to analytically calculate core decay ratios, was used to calculate the core decay ratios at the Susquehanna SES Unit 2 test conditions.

The cross-sections for the core simulator model XTCBWR were generated with the assembly depletion model XFYRE( }.

The reactor core at the reported test

}

conditions was modeled explicitly with the core simulator model XTGBWR using data obtained from the POWERPLEXe Core Monitt ring Sof tware System.

Included in tnis data were the control rod density, core pressure, total core flow, and core thermal power.

Data calculated with XTCBWR and used 5

in the COTRAN core stability calculation included the axial average cross sections, bypass flow, power distribution, xenon distribution, and the core axial pressure drop.

l The decay ratio calculations performed with the COTRAN model are performed In the time domain which allows for an easy computation of the core decay ratio. The change in power is calculated by COTRAN as a function of time following a simulated step perturbation in the core pressure.

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I II 11 XN-NF-86-90 Supplement 1 Decay Ratios calculated by COTRAN for the two-loop test and single loop l

t test are DR - 0.33 and DR - 0. 29, respectively.

Table 4.1 shows that I

these calculated decay ratios are consistent with decay ratios determined l

by ENC using the APRM data recorded by GETARS and the ORNL algorithm.

4.2 COTRANSA-2 Sta]2111tv Analyses COTRANSA-2 (Reference 3),

a reactor system stability model which couples l

core neutronics, core thermal hydraulics, and the recirculation loop was developed to determine BWR system stability with two-loop and single loop forced convection in addition to natural circulation.

This system is a dynamic code that accounts for feedback between components of a system.

Conditions from both Susquehanna Unit 2 Cycle 2 stability tests were simulated with the COTRANSA-2 model. A decay ratio of 0.32 was calculated for the two-loop test and 0.24 was calculated for the single loop test.

Table 4.1 shows that these calculated decay ratios are consistent with the

" measured" decay ratios determined by ENC using the APRM data recorded by GETARS and the ORNL algorithm.

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!I TABLE 4.1 COTRAN AND COTRANSA-2 CALCUIATED DECAY RATIOS

!I Two-Looo Decay Ratio Single Loon Decay Ratio COTRAN

.33

.29 COTRANSA-2

.32

.24 Measured

.33 (a - 0.064)

.30 (a - 0.064)

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I 13 XN-NF-86-90 Supplement 1

5.0 CONCLUSION

Stability tests performed at Susquehanna SES Unit 2 during the first several weeks of Cycle 2 operation show that the Cycle 2 core containing the 9x9 reload fuel is very stable. Noise monitoring, COTRAN calculations (Table 4.1), C0TRANSA 2 calculations (Table 4.1), and ENC decay ratios based on noise analyses confirm consistent and very low decay ratios for the core.

When comparing the single loop decay ratio to the two-loop decay ratio, no significant changes in stability margin are observed that clearly stand out beyond the inherent accuracy of the results.

Consistency of results from these tests and calculations also adds to the confidence in the reliability of the ENC stability methodology to predict core stability for cores containing 9x9 reload fuel.

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14 XN-NF-86-90 Supplement 1

6.0 REFERENCES

1.

" Exxon Nuclear Methodology for Boiling Water Reactors Neutronics Methods for Design and Analysis,"

XN-NF-80-19(A),

Volume 1.

Supplements 1 and 2, Exxon Nuclear Company, Richland, WA 99352, March 1983.

2.

" Stability Evaluation of Boiling Water Reactor Cores," XN-NF-691( A),

as supplemented, Exxon Nuclear company, Richland, WA 99352, August 1984.

3.

" Stability Evaluation Metnodology for BWR Cores," XN-NF-84-67(P), as supplemented, Exxon Nuc1riar Company, Richland, WA 99352, June 1984.

4.

J.

March-Louba, " Dynamic Behavior of Boiling Water Reactors," PhD

[

Dissertation, University of Tennessee, Knoxville (1984).

5.

"BWR Core thermal Fydraulic Stability," General Electric, SIL No.

380, Rev. 1, February 10, 1984.

6.

" Exxon Nuclear Mothodology for Boiling Water Reactors, Volume 1,

Neutronics Methods for Design and Analysis," XN-NF-80-19(A), Volume

[

1, and Supplements, Exxon Nuclear Company, Richland, WA 99352, June 1980.

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XN-NF-86-90 Supplement 1 Issue Date:

1/28/87 I

SUSQUEllANNA UNIT 2 CYCLE 2 STABILITY TEST RESULTS I

I Distribution:

I R. E. Collingham G. C. Cooke S. F. Gaines I

K. D. Ilartley S. E. Jensen S. W. Jones T.11. Keheley I

T. L. Krysinski D. G. McAlees J. N. Morgan E

L. A. Nielsen g

T. W. Patten D. W. Pruitt l

C. L. Ritter

11. G. Shaw/PP&L (70)

G. A. Sofer G. N. Ward I

J. A. White j

11. E. Williamson t

l Document Control (5) lI I

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