ML20215M235
| ML20215M235 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 08/21/1986 |
| From: | Ingersoll K OAK RIDGE NATIONAL LABORATORY |
| To: | NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| NUREG-CR-4439, NUREG-CR-4439-ERR, ORNL-TM-10132, NUDOCS 8610300120 | |
| Download: ML20215M235 (7) | |
Text
.
T OAK RIDGE NATIONAL LABORATORY
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OPERATED BY MARTIN MAAIETTA ENERGY SYSTEMS. treC-August 21, 1985 To:
Recipients of Subject Report Report No.
NUREG/CR-4439 (ORNL/TM-10132)
Classification:
Unclassified Author:
R. E. Maerker Please correct your copy (ies) of the above subject report by affixing the attached corrected pages, which have been prepared on self-adhesive stock.
The list of references should be affixed to blank page 60.
Katic Ingersoll Reports Office Engineering Physics and Mathematics Division Attachments 8610300120 860821 PDR ADOCK 05000261 p
1 TABLE OF CONTENTS 1
l Section Page I.
INTRODUCTION..................................................
1 II.
CALCULATIONS OF ACTIVITIES AND PRESSURE VESSEL FLUENCES DURING CYCLE 9................................................ 5 II.A.
Geomet ry and Materi al s Descripti on.....................
5 II.B.
Sou rc e De s c ri pt i o n.....................................
5 II.C.
Reference Calculations................................. 9 II.D.
Time-Dependent Cal cul ati ons...........................
11 II.E.
Calculated End-of-Cycle Activities and Comparison with Measurements.....................................
15 II.F.
Calculated End-of-Cycle Critical Pressure Vessel F l u e n c e s..............................................
17 III.
ESTIMATED UNCERTAINTIES IN THE CALCULATED RESULTS............
21 IV.
ESTIMATED UNCERTAINTIES IN THE MEASUREMENTS..................
35 IV.A.
Random Counting Uncertainties.........................
35 IV.B.
Systematic Efficiency Uncertainties...................
35 IV.C.
Bi as Facto r Unce rt ai nt i es.............................
37 IV.D.
Normalization Uncertainties...........................
37 V.
RESULTS OF TH E ADJ USTMENT....................................
41 V.A.
Adjusted Activities for the Optimum Case.............. 41 V.B.
Unfolded Critical Pressure Vessel Fluxes..............
44 V.C.
Adjustments in the Parameters......................... 48 V.D.
Adjusted Critical Pressure Vessel Fluences............
52 VI.
SU MMAR Y AND CO NCLU S ION S......................................
55 ADDENDUM.....................................................
57 ACKNOWLEDGMENTS..............................................
59 REFERENCES...................................................
60 iii
i l
ABSTRACT A second example of applying the LEPRICON methodology to an existing pressurized water reactor is described. The present application is an analysis of ad hoc dosimetry inserted into the H. B. Robinson-2 reactor to monTtor the effects on pressure vessel fluence produced by the introduction of a low-leakage fuel management scheme during cycle 9.
The use of simultaneous dosimetry both at a downcomer location and in the reactor cavity allowed a quantitative evaluation to be made by the LEPRICON procedure of the relative merits of each location. Unfolded results using the dosimetry indicate that the cumulttive neutron fluence above 1 MeV originally calculated for the critical lower circumferential weld in the pressure vessel during cycle 9, 7.2x10 17 2
n/cm 115.9 percent, should be adjusted upward by about one standard deviation to a value of 8.8x10 17n/cm2 with a reduced uncertainty of 10.9 percent.
ix C
LEPRICOM ANALYSIS OF PRESSURE VESSEL SURVEILLANCE DOSIMETRY INSERTED INTO H. 8. ROBINSON-2 DURING CYCLE 9 I.
INTRODUCTION The theory of the generalized linear least-squares combination proce-dureugedintheLEPRICONadjustmentmoduleoftheLEPRICONcomputercode system and the application of the procedure to pressure lance dosimetry were described in an earlier publication.gessel surveil-I I
Also described was the development of a dosimetry benchmark data base that could be used in the combination procedure to permit a simultaneous adjustment of the benchmark data with measurements performed in a pressurized water reactor (PWR).
3 A second paper described the extension of the LEPRICON code system to include additional modules which provide standard methods for calculating a priori pressure vessel fluence and dosimeter activity estimates with transport theory using the method of discrete ordinates. Results of an application using portions of this expanded LEPRICON system to measurements performed in the cavity of the Arkansas Nuclear One-Unit I reactor (ANO-1) were also presented in great detail.
Among the methods introduced in this generalized LEPRICON code system are procedures for incorporating the results of core physics calculations with in-core measurements to provide sources for the transport codes.
Another technique involves the use of a single adjoint function in conjunc-tion with the results of a forward transport calculation to obtain accurate estimates of the effects of time-dependent source spatial distributions on dosimeter activities and p ssure vessel fluences. These procedures were described in a third paper The purpose of this paper is to present the results of a second application of the LEPRICON system to an on-line PWR, this time using the complete set of modules which are in the process of being fully documented by the Electric Power Research Institute (EPRI), thus supplementing the earlier experience with ANO-1, a Babcock and Wilcox designed reactor. This new application is to the H. B. Robinson-2 reactor (HBR-2), a 2300-MW (thermal) PWR designed by Westinghouse (W) and placed in operation in March of 1971. This three-loop reactor is representative of an older class of W reactors which are further characterized by a relatively narrow 170.7-mm (6.72-in.) annular reactor cavity. Conventional dosimetry (i.e., sequen-tial extraction of downcomer-positioned surveillance capsules only) had been utilized over the first eight cycles of reactor operation.
Investiga-tions into pressurized thermal shock (PTS) suggested that the accumulation of fast neutron fluence should be reduced for reactor operation in order to maintain an adequate margin for the PTS at such locations as the lower circumferential weld (LCW). Two measures were adopted to this end.
1
52 also assumed to be the same (see Table IX), the adjustments at both pres-sure vessel locations are identical and are due to an inferred decrease in the downcomer thickness of about 6 mm (0.24 in.) from its nominal value.
V.D.
Adjusted Critical Pressure Vessel Fluences Values of the adjusted group fluences accumulated during cycle 9 at each of the two pressure vessel locations may be readily obtained by multiplying the entries in Table VIII by the adjustment factors appearing in the last columns of Tables XXIII and XXIV. These adjusted fluences appear in Table XXIX. Values of three weighted pressure vessel fluences for both the calculated and adjusted cases are shown in Table XXX. The adjusted values are seen to average ~20 percent higher than the originally calculated values for either pressure vessel location and the standard deviations have been reduced from about 16 to 11 percent, i
Table XXX. Weighted Fluences at the Critical Pressure Vessel Locations Accumulated During Cycle 9 with Standard Deviations Before and After Unfolding LCW Location T/4 Location Before After Before After
$ l l
Fluence above 1.00 MeV 7.23(17) 21.15(17)a 8.75(17) 2 0.96(17) 3.86(17) 1 0.66(17) 4.78(17) 1 0.50(17)
Fluence above 0.098 MeV 1.99(18) 1 0.30(18) 2.37(18) 0.27(18) 1.68(18) 0.26(18) 2.05(18) 1 0.22(18) dpa above 0.098 MeV 1.11(-3) 2 0.17(-3)b 1.34(-3) 1 0.15(-3) 7.16(-4) 1.13(-4) 8.85(-4) 0.92(-4) 1 aRead as 7.23 x 10 17 1.15 x 10 17 2
n/cm,
bread as 1.11 x 10-3 2 0.17 x 10- 3 displacements per atom of iron.
l I
~
~
60 REFERENCES 1.
Sponsored by the Electric Power Research Institute, Palo Alto, CA.
2.
R. E. Maerker, B. L. Broadhead, and J. J. Wagschal, Nucl. Sci. E_ng.,
91, 369 (1985).
3.
R. E. Maerker, B. L. Broadhead, B. A. Worley, M. L. Williams, and J. J. Wagschal, Nucl. Sci. Eg., 93, 137 (1986).
4.
R. E. Maerker, M. L. Williams, and B. L. Broadhead, Nucl. Sci. E_ng.,
to be published.
5.
"H. B. Robinson Fluence Reduction Analysis for the Partial-Length Shield Assembly Concept," TEC Report R-83-030, Technology for Energy Corporation and Carolina Power and Light Company (1983).
6.
Reactor Physics Constants, ANL-5800 Second Edition, Argonne National Laboratory, p. 660 (1963).
7.
S. L. Anderson, Westinghouse Electric Corporation, Private Communica-tion (1986).
8.
W. Weikel, EBASCO, Private Communication (1986).
9.
I. Remec, Oak Ridge National Laboratory, Private Communication (1986).
10.
M. L. Williams, R. E. Maerker, W. E. Ford, III, and C. C. Webster, "The ELXSIR Cross-Section Library for LWR Pressure Vessel Irradiation Studies:
Part of the LEPRICON Computer Code System," NP-3654, Electric Power Research Institute (1984).
11.
B. L. Broadhead, R. E. Maarker, and J. J. Wagschal, "The LEPRICON Adjustment Module:
A Generalized Linear Least Squares Data Analysis Program with Application to PWR Surveillance Dosimetry," Electric Power Research Institute, to be published in 1986.
12.
F. B. K. Kam, Oak Ridge National Laboratory, Private Comunication (1984).
13.
W. K. Cantrell, Carolina Power and Light Company, Private Communica-tion (1986).
14.
E. P. Lippincott, Westinghouse Electric Corporation, in collaboration with L. S. Kellogg, Hanford Engineering Development Laboratory, Private Communication (1986).
15.
R. E. Maerker, " Gamma-Ray Characterization of the Two Year Irradiation Experiment Performed at the Poolside Facility," NUREG/CR-4039, ORNL/TM-1440, Oak Ridge National Laboratory (1985).
16.
C. M. Eisenhower, National Bureau of Standards, Private Communication (1984).
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