ML19209A163
| ML19209A163 | |
| Person / Time | |
|---|---|
| Issue date: | 09/25/1979 |
| From: | Brooks W Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19209A162 | List: |
| References | |
| NUDOCS 7910030041 | |
| Download: ML19209A163 (5) | |
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Review of BAW-10ll8, " Core Calculation Techniques and Procedures" Report Number:
BAW-10ll8 Report
Title:
Core Calculation Techniques and Procedures Report Date:
October 1977 Originating Organization:
Babcock & Wilcox Reviewed by:
Core Performance Branch /W. Brooks The Power Generation Group of Babcock and Wilcox has submitted licensing topical report BAW-10ll8 entitled " Core Calculation Techniques and Procedures" for our review. This report describes the procedures and techniques employed by Babcock and Wilcox in core design analysis of power peaking, control rod worths, and reactivity coefficients.
It is one of a series of topical reports which have been submitted by Babcock and Wilcox in order to provide the staff with generic information on the nuclear design of B&W reactors.
1.
Summary of Report BAW-10ll8 describes the procedures and techniques employed by Babcock and Wilcox in core design analyses of power peaking, control rod worths ara reactivity coefficients.
Emphasis is placed on current calculati,nal techniques with brief descriptions given of previou. models and proce6res to provide historical background of the analyses.
One, two, and three-dimensional power distributions are described. One-dimensional calculations are performed to obtain detailed axial power profiles in the core or a particular assembly.
In particular, such calculations are used to obtain the peaking effort of spacer grids. Two calculations are perfonned - one in which the spacer materii,is are homogenized over the length of the assembly (as is done in the two-and three-dimensional calculations) and one in which the spacer materials are represented explicitly in their proper locations.
The ratio of the two power densities at a particular elevation is then the axial-local peaking factor for that location.
003d eg 91 1084 246
~.
Two-dimensional (x-y) power distributions are performed with the PDQ07 code in the discrete mode in which each fuel pin is separately represented. These calculations are used to obtain radial power distributions and radisi-local peaking factors (the ratio of the peak power in the assembly to the average assembly power). Depletion calculations are perfonned in two dimensions with thermal hydraulic feedback. The core conditions and basic time intervals for the depletion calculation are described.
The procedures for the modeling of fuel movement in core reloads is described. A PDQ07 service routine SHUFFLE is used for this purpose.
The major portion of the power distribution calculations performed by Babcock and Wilcox are three-dimensional. The results of these analyses are used to establish safety limits and limiting conditions of operation.
Two computer codes - PDQ07 and FLAME 3 are used for three-dimensional calcul'ations.
The models used in the calculations, including boundary conditions, are described.
The procedures employed for core depletion are described and a list 'of typical calculations during a depletion cycle is presented.
Power transients are perfonned during each cycle. The proceddres for performing these are described.
The calculations required for establishment of protection limits and limiting conditions for operation are discussed.
Analyses of total pattern and group control rod worths are performed as part of core design. The models and techniques used to obtain total worth and the shape of the group worth curves are described.
The PDQ07 c.1d FLAME 3 codes are used for this purpose. Generally, the total group worths are obtained from two-dimensional discrete PDQ07 calculations and group worth curves are obtained from three-dimensional PDQ07 or FLAME 3 calculations.
Calculations are performed at hot zero power for all arouos (1 throuah 7) and at hot full power conditions for the regulating groups (5 through 7).
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. Single rod worths - ejected rod worth, stuck rod worth, dropped rod worth -
are calculated as part of the design analyses. The ejected and stuck rod worths are calculated by two-dimensional PDQ07 in the discrete full core model. Dropped rod worths and out-of-sequence rod anomalies are determined by three-dimensional FLAME 3 calculations.
Of interest in these calculations, in addition to rod worths, are the power distribution perturbations caused by the dropped or out-of-sequence rods.
Moderator temperature, fuel temperature (Doppler) and power reactivity coefficients are calculr.ted as a routine part of the core design procedure.
In addition, pressure coefficier,ts and void coefficients are calculated less frequently. Reactivity coefficient calculations are performed with the PDQ07 code, and are direct in nature. That is, a base core calculation is performed,
the relevant parameter is varied by a small amount and the calculation is repeated. The coefficient is then the difference in reactivity between the two cases divided by the change in the controlling parameter. Calculations
' techniques are described, including the manner in which interactions between different coefficients are treated.
2.
Summary of Evaluation We reviewed the descriptions of the procedures and techniques used in the design analyses of power peaking, control rod worths, and reactivity coefficients which are presented in topical report BAW-10ll8. The following discussion summarizes our findings.
power distributions are calculated by the PDQ07 and FLAME 3 codes.
Topical reports describing these codes have been reviewed and approved.
Detailed two-dimensional calculations are performed to obtair 'Jadial power distributions.
Axial power distributions are not routinely calculated.
Instead three-dimensional 1084 248
power distributions are calculated and axial distributions obtained by dividing by the radial distributions.
In this manner the effects of any lack of separability in axial and radial distributions is automatically included.
This is an improved procedure over synthesis methods and'is acceptable to obtain axial-local peaking factors and use of a single bounding value of this quantity is conservative and is acceptable.
The techniques and procedures used to obtain control rod group worths have been reviewed. Normalization of the control rod worth curves to the total worth calculated in two dimensions is state-of-the-art and is acceptable.
The calculation of single rod worths is performed in ful!-core representation which accounts for power distribution distortion effects on the rod worth.
Reactivity coefficient calculations are performed at zero power, and, in the case of the power coefficient, at intermediate powers.
Isothermal temperature changes (in fuel or moderator). are assumed at zero power and are acceptable.
Thermal feedback effects (which alter the distributions of temperature changes) are included for the at-power calculations. This is state-of-the-art and is acceptable.
Pressure and void coefficients are calculated in a straight-forward acceptable procedure. Special cross-section sets are prepared for the PDQ07 codes for the performance of these calculations.
Calculations of power distributions, control rod worths, and reactivity coefficients have been compared to measured values and the results presented in topical reports which have been reviewed and approved. These comparisons confirm that the procedures and techniques employed ire acceptable.
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3.
Evaluation Procedure The review of topical report BAW-10ll8 has been conducted within the guidelines provided by the' Standard Review Plan, Section 4.3.
Sufficient information is presented to permit a knowledgeable person to conclude tha't the calculational procedures and techniques used are state-of-the-art.
This conclusion is reinforced by the fact that comparison of calculated results with measurements have been performed which show that the procedures and techniques produce acceptable results.
4.
Regulating Position On the basis of our review of licensing topical report BAW-10118 we conclude that it is acceptable for reference in licensing actions in regard to core calculation techniques and procedures.
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