Neutron and photon effective dose equivalent rate calculations for the repackaging of tru waste Page: 4 of 5

                                
Table 1. Total (Neutron and Photon) Dose Rates in Locations A-F (mSv/hr).
Location
Horizontal Supply
Drum Content (W)
A        B       C        D       E       F
0.5 W      3.42E-03  7.67E-03  9.63E-03 1.68E-03 5.44E-03 1.16E-01
1 W        5.16E-03  7.73E-03  9.67E-03 1.70E-03 5.46E-03 1.16E-01
5 W        1.91E-02  8.16E-03  1.00E-02  1.85E-03  5.66E-03  1.17E-01
low        3.66E-02  8.70E-03  1.04E-02 2.03E-03 5.90E-03 1.18E-01
20 W       7.15E-02  9.78E-03  1.12E-02 2.40E-03 6.39E-03 1.20E-01
30 W       1.06E-01  1.09E-02  1.20E-02 2.77E-03 6.88E-03 1.21 E-01
40 W       1.41E-01  1.19E-02  1.28E-02  3.14E-03  7.37E-03  1.23E-01

The highest dose rate occurs in Location A (Figure
1), in front of the horizontal feed drum when it
contains 40 W. This is expected because 40 W is
the maximum amount of material in any of the
source geometries. However, the wattage of the
supply drum will vary as will the dose rate. A
greater concern will be the dose in the storage
area. The storage area will hold 20 drums with a
minimum of 1 W each. The dose rate in the
storage area is 0.12 mSv/hr.
Photon dose rates are lowered by the stainless
steel glove box. If the material from the drum is
inside the glove box, the dose rate will be reduced
by a factor of four. The 0.16 cm leaded glass
placed over the glove box windows will reduce the
dose by a factor of nine.
The aforementioned calculations were based on
the assumption that all doors to the transportainer
and the storage area were closed. Three doors
were considered to be important for additional
calculations: the door between the storage area
and the spool, the door between the spool and the
transportainer and the door in the storage area
opening to the outside. If the door between the
storage area and the outside is open, the photon
dose in front of the open door (location E, Figure
2) is a factor of 10 higher than if the door were
shut. The neutron dose remains the same.
The dose inside the transportainer is affected
when the door between the storage area and the
spool is open or the door between the spool and
the

transportainer is open. The neutron dose remains
the same regardless if one door or the other is
open. The photon dose rate in this case increases
by 30-50% pending the location in the
transportainer.
CONCLUSION
These calculations indicate that the dose rates
from the repackaging process can be
accommodated in the transportainer.
REFERENCES
1. "Design Requirements Document and
Preconceptual Design, Modular Characterization
and Repackaging Units for TRU Wastes," TWCP-
05503 (June, 2001).
2. George, G., "Effective Dose Equivalent (EDE)
Rate Calculations for the Pu-238 Recovery
Process," ESH-12-00-34 (March 27, 2000).
3. Reilly, D., N. Ensslin, H. Smith, Jr., S. Kreiner,
Eds., Passive Nondestructive Assay of Nuclear
Materials, Nuclear Regulatory Commission Report
NUREG/CR-5550 (1991).
4. Briesmeister, J.F., Ed., "MCNPTM A General
Monte Carlo N-Particle Transport Code," Version
4C, Los Alamos National Laboratory Report LA-
13709-M (2000).
5. "American National Standard for Neutron and
Gamma-Ray Flux to Dose Rate Factors,"
American Nuclear Society, ANSI/ANS-6.1.1-1977.