Glove box

  1. 1. Schematic diagram of O/M analysis apparatus. (D Helium bomb; (2) Balance; (3) Upper elcctrodc: (D Graphite crucible: (5) Lower electrode: © Electrode driving cylinder: (D Dust filter; © Refrigerator; CD Power supply, © Compressor; © Gas dilution vessel; © Pressure regurator; © Needle valve; © Nondispersive infrared spectrophotometric detector; © Integrator; © Operating controller.
  2. 1. Schematic diagram of O/M analysis apparatus. (D Helium bomb; (2) Balance; (3) Upper elcctrodc: (D Graphite crucible: (5) Lower electrode: © Electrode driving cylinder: (D Dust filter; © Refrigerator; CD Power supply, © Compressor; © Gas dilution vessel; © Pressure regurator; © Needle valve; © Nondispersive infrared spectrophotometric detector; © Integrator; © Operating controller.

continually heated at about 2000°C for 30 s and 2500°C for 30 s in a current of helium gas. The 02 in the sample was quantitatively reacted with carbon in the graphite crucible, and the CO was evolved. These gases were transferred to the buffer vessel and diluted by helium carrier gas. The CO diluted was determined using the NDIR, and the peak-area was integrated using a computerized integrator. The concentration of 02 in the nickel capsule and the crucible was analysed beforehand and this blank value was deducted from the sample analysis value. The O/M of the sample was calculated using the following equations:

where Co is the concentration of 02in the sample (wt%), Ceo is the analysis result of CO using the present method (wt%), Mo and Mc are the atomic weights of 02 and carbon, M is the mean atomic weight of metal in the sample, and X is the O/M ratio. Equation (3) was derived from equation (2).

  1. 2 RESULTS
  2. 2.1 Calibration curve

The calibration curve for the determination of 02 was obtained using a O/M = 2.00 controlled MOX fuel by varying the weight over the range of 10 to 60 mg. The calibration curve obtained is shown in Fig. 2. The calibration curve gave good linearity in the range of 1.2 to 7.2 mg for the theoretical value of oxygen content.

2.2.2 Comparison with gravimetric method and precision

The O/M ratio measurement for the sintered MOX fuel pellet containing less than 10% plutonium has been determined using die oxidation weighing method [1]. On the other hand, for sintered MOX fuel containing more than 10% plutonium the O/M ratio has been determined using the oxidation-reduction method [2,3]. These methods are based on gravimetry.

In order to compare the gravimetric method and presented method, sintered MOX fuels containing about 3% plutonium was used. Moreover, accuracy of this method was measured using 25% plutonium MOX. The measurement results of the O/M ratio are shown in Table I and Table 2. The result of the present method was in good agreement with the gravimetric methods. The RSD was less than 0.20%, and the time required for one determination was about lOmin for all analytical operations

Co Co X

Mo/(Mc + Mo) x Ceo . Mo X/(M + Mo-X) x 100 Co- M/(100 - Co) x 1/Mo

O 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Theoretical value of oxygen (mg)

Fig. 2. Calibration curve for oxygen.

O 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 Theoretical value of oxygen (mg)

Fig. 2. Calibration curve for oxygen.

TABLE 1 Comparison of the gravimetric method and the present method for O/M analysis in 3% plutonium MOX

Method

O/M ratio"

Gravimetric method

2.003, ± 0.0034

Present method

2.004, ± 0.0037

a Mean ± standard deviation (n = 8)

TABLE 2 Determination of O/M in 25% plutonium MOX by the present method

Expt. No.

O/M ratio

1.

1.975

2.

1.985

3.

1.977

4.

1.980

5.

1.984

6.

1.978

7.

1.977

8.

1.981

Mean Value

1.9796

SD

0.0035

RSD (%)

0.179

SD Standard deviation

RSD Relative standard deviation

RSD Relative standard deviation

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