Facility Support Systems

DOE-HDBK-3010-94

Appendix B; Plutonium Recovery Facility

2.1.5

F acility S u p p ort S ystem s

2.1.5.1 N u clear Incid en t M on itors

Twelve sets of two nuclear criticality incident monitors each detect and alarm in excessive

radiation fields. These detectors are spaced so as to provide overlapping coverage by a

minimum of three detectors at any point in the facility. They provide flashing light and bell

ringing indications when activated. The units are designed to alarm on any internal failure

and receive power via an uninterruptable power supply.

2.1.5.2 N u clear C riticality D esign M itigation an d C on trol S ystem s

With the exception of the tanks in the vessel vent room, the plenum deluge catch tank, and

the utility room reboiler and its associated condensate tank, all vessels within H Plant are

geometrically favorable in design. Tanks in gloveboxes are slab tanks with a nominal

interior width of 3 inches with reinforcing stay-bolts and weep holes to detect corrosion

before it can alter control dimensions. Tanks outside gloveboxes in the wet line tank farm

are annular vessels with a maximum interior annular diameter of 2 inches. These vessel

sizes ensure a subcritical condition for all flowsheet plutonium concentrations, thus

preventing a criticality from inadvertent transfer of a solution to the wrong tank. The vessels

previously mentioned that are not geometrically favorable are equipped with borated raschig

rings to prevent criticality from inadvertent plutonium accumulation due to abnormal

conditions.

Glovebox sumps are built into the bottom of all wet process enclosures well below the level

of any vessels. Each glovebox is equipped with three separate slab sumps. The sumps are

sized so that, in combination, they can hold all of the liquid in the largest vessel in a

glovebox when sloping of the lower surface causes overflow from one sump to go to the next

sump in line. All sumps are equipped with liquid level detectors that provide local and

remote alarms and shut the inlet valves for the main process liquid streams.

The process solution tank farm area has been sized so that all of the liquid available in the

tanks should be able to spread across the floor in a thin enough layer to preclude a criticality

from occurring due to leaks. However, as an additional safeguard, the storage tank areas

have metal-grating floors elevated over a pit filled with borated raschig rings.

All vessels and storage arrays in H Plant have been spaced so as to maintain the materials at

geometrically favorable spacings. All transfers of material, whether feedstock, product, or

waste pails, are limited to one unit at a time. Portable and in-line holdup monitors are used

to measure plutonium accumulation in systems as well.

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