Differential Rod Worth

The water temperature coefficient for the UWNR is +1. OE-4 AK/K/deg.C. When the water temperature decreases by 10 deg C, to remain at constant power a regulating blade with a Differential Rod Worth of 0.05 % AK/K/inch would be ... 

A reactor is critical at 18.1 inches on a controlling rod. The controlling rod is withdrawn to 18.4 inches. The reactivity inserted is 14.4 cents. What is the differential rod worth ... 

Which ONE of the following correctly describes the relationship between Differential Rod Worth (DRW) and Integral Rod Worth (IRW) ... 

Control rods are moved axially in discrete increments between fully inserted and fully withdrawn. Each incremental change in rod position produces a reactivity insertion in the reactor. A plot of incremental reactivity (AK/K/in) as a function of the axial rod position (in) in the core is called a differential rod worth curve. 

Repeat this procedure over the full length of the rod. At each pull, plot differential reactivity versus the midpoint of the pull. The cumulative plot, as shown in Figure 7.i.d is the differential rod worth curve. At the two end points, the top and bottom of the core, differential rod worth is zero. Two orientations of the curve are shown. The left curve has rod position vertical just as the rod moves in the core. The right curve is reoriented in the more traditional manner with rod position along the horizontal axis. 

Typical Differential Rod Worth as a Function of Axial Control Rod Position... 

Through circumstances due to experimental loading and xenon concentration, the differential rod worth of particular rods at a particular time are found to be of the shape ... 

What data is taken in order to generate a control rod differential rod worth curve Be specific on method used and readings/measurements taken. 

Explain (sketches might make it easier) the difference between differential and integral rod worth curves for UWNR. 

Choose the statement that best defines differential control rod worth. 

The integral rod worth curve is a plot of the summed area under the differential curve up to a designated rod position. The value of the integral worth is the cumulative effect of withdrawing a control rod a specific distance from the core. 

Construct an integral rod worth curve from a differential curve or from differential data. 

Differential reactivity at any rod position corresponds to the amount of reactivity that one inch of rod motion would insert at that position, The differential reactivity is lowest at the top and bottom of the core and greatest at the center. This exactly corresponds to core flux shape. A rod has the greatest reactivity effect when it is moved in the highest flux because rod worth is simply an absorption reaction rate, R = It is... 

Construction of an integral rod worth curve from a differential worth curve is illustrated in Figure 7.2. Starting at the bottom of the core, move up one inch of rod position. At that point, observe the differential worth value. That value is not truly representative of the differential worth over the first inch. Some lower value is. The product of the estimated differential worth times the inch of motion is the cross hatched rectangular area shown on Figure 7.2.a. The cross should be equal to the actual area under the curve position. The actual area, which is the summed or up to that position, is shown dotted in Figure 7.2. of the hatched area are differential worth (AK/K/in... 

Sketch and label a differential control rod worth curve. 

Control rod worths (differential and total, shutdown margin)... 

Reactor physical characteristics have also drawn much attention. The control rod worth, including the differential worth and integral worth, were calculated by the Monte Carlo code for neutron and photon transport (MCNP) for the 2 MW TMSR-SE (Zhou and Liu, 2013). The measurement of the neutron energy spectrum was also theoretically and experimentally studied (Zhou, 2013). Parametric study of the thorium-uranium conversion rate was conducted to optimize the core structure for the improvement of the economics of the TMSR using the standardized computer analyses for licensing evaluation (SCALE) code (Wang and Cai, 2013). 

The eiq riment consisted of measuring the critical rod-bank bei t and differential worth of the core alone, the core with the empty container, and with 2,4, and 6 la. of lead in the ccmtainer. The rod bump method in con-... 

A weighted least-squares method was used to fit a straight line to the inverse cube root of the differential worth vs rod-bank height. Hie integral of the differential worth from the critical rod-bank configuration to an all-rods-out configuration was then taken to be the excess reactivity of that particular core configuration. 

As a control rod is withdrawn from fully inserted to the center of the core, its differential worth will ... 

Which ONE of the following factors is the most significant in determining the differential worth of a control rod ... 

The completed flight power unit was to be received from the core vendor. Zero-power physics tests were to be performed to confirm that no significant manufacturing errors exist, and to obtain an initial physics characterization of the reactor. Measurements include reflector critical positions, differential and integral worth of reflectors, and integral worth of safety rod. 

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