Port Inserts

DOE-STD-3007-93

contains a fuel crib where the fuel sits during dissolution. The bottom of the dissolver contains an

air sparge ring which provides agitation.

2.2

Port Inserts

There are four access ports, 90 apart, around the top of the dissolver (Figure 2) which are used

to place material into the inner annulus of the dissolver. Mark-42 inserts (each containing two

TRR inserts as shown in Figure 3) and a 3-well insert (Figure 4) will be placed into the dissolver

ports to hold TRR bundles, with each TRR bundle holding one TRR rod. Each Mark-42/TRR

insert has locations to hold six TRR bundles. The 3-well insert contains three cylindrical tubes

(wells) which can each hold a TRR bundle. The inside diameter-of each well in the 3-well insert is

5.487". It is planned to place the EBR-II bundle into the dissolver without using an insert in the

port, since the EBR-II bundle is too large to fit into either of these inserts. The EBR-II bundle

will simply be lowered by the crane through one of the ports to sit on the bottom of the dissolver.

2.3

Materials to be Dissolved

Each assembly used in the blanket of EBR-II contained 19 rods, each containing 5 depleted

uranium (0.22% U-235) slugs, 0.433 inch OD x 11 inches long, sodium bonded to 304 stainless

steel cladding. As a result of irradiation in EBR-II, these slugs bred varying amounts of

plutonium, depending on their location and residence time in the blanket of EBR-II. At

Rocketdyne in the mid 1980s, these EBR-II blanket assemblies were processed by removing the

steel cladding and sodium from the blanket slugs, and loading them into thin-walled aluminum

tubes (up to 14 slugs per tube). These aluminum tubes containing the slugs were bundled

together, with each bundle containing 41 tubes. Each bundle was then placed into a welded

aluminum can. Each can was 14 ft. long, with a diameter small enough to fit into the wells of the

3-well insert (< 5.375 in.). Each bundle in a can could hold the slugs from up to 6 blanket

assemblies (6 x 19 x 5 = 570 slugs). EBR-II can DU006 was produced by this process, and was

originally received at SRS in 10-86. In June 1992, can DU006 was found to have failed due to a

lid weld defect. The can was then encapsulated in a vented overpack bundle, and isolated on 11-

17-92 in row 15 of Bundle and Test Tube Storage at the Receipt Basin for Offsite Fuels (RBOF).

The OD of the overpack bundle is 6.469 inches. This dimension is too large to fit into a dissolver

insert well, so that DU006 will have to be placed into the dissolver without using an insert in the

port. The heavy metal weights in DU006 are given in Table 1 as 285 kg of uranium, 0.628 kg U-

235, and 0.789 kg of plutonium. The plutonium composition should be greater than 98% Pu-239.

It is planned to dissolve this bundle during the dissolving of failed Taiwan Research Reactor

(TRR) fuel that is also targeted for processing.

TRR fuel is natural uranium metal rods (1.36" OD and 120" long) in aluminum cladding (1.52"

OD), and has historically had nominal weights of 1.45 kg Al, 0.065 kg Pu, and 53.6 kg U per rod

(Ref. 3). The TRR fuel to be processed consists of 81 failed fuel rods currently stored in RBOF.

The condition of these rods ranges from those which are still intact but have an indication of

breached cladding, to those that are fully oxidized, to bits and pieces mixed with oxide. These 81

6-6