Example 7: Consideration of Facility Disposition Impacts on Adjacent Facilities

DOE-STD-1120-2005/Vol. 2

summarized and referenced analyses showing that a criticality event is not credible. The description of

the grouting process clearly specified that the technique does not bring the waste material to the surface as

a "pump and treat" condition eliminating that IWS prohibition. The only remaining IWS

assumption/condition is the intrusive activity of installing the piping and injecting the grout. The

intrusive activity of installing the piping and injecting the grout is evaluated using the unmitigated

allowances of DOE-STD 1027-92, Hazard Categorization and Accident Analysis Techniques for

Compliance with DOE Order 5480.23, Nuclear Safety Analysis Reports, section 3.1.2, Final Hazard

Categorization.

Evaluation of the intrusive activity for Final Hazard Categorization considers the quantity (no additional

inventory brought onto the site other than sealed sources required for calibration of equipment), location

(waste remains below ground) and waste interaction with available energy (not capable of generating a

significant release). These key assumptions and conditions were maintained as condition for approving

the facility categorization as a "below Category 3" activity.

Example 7:

Consideration of Facility Disposition Impacts on Adjacent Facilities

A retired tritium facility had a 200-ft.-high, 10-ft.-diameter, reinforced brick-lined concrete stack that was

to be demolished using explosives. A hazard analysis was performed to identify the hazards and requisite

controls related to the demolition activities. The hazard analysis also examined the stack's close

proximity to several operating nuclear facilities (some of these facilities' safety class equipment was less

than 300 feet away from the stack). The hazard analysis considered hazards related to stack materials and

hazards introduced from the chosen work method. These hazards included seismic effects, tritium release

from the stack materials on impact, propagation of pressure waves, and projectiles. Additionally, the

analysis was benchmarked with another similar activity at a commercial reactor site and related lessons

learned from other DOE sites were reviewed.

The hazard analysis identified safety controls, including the use of mobile SeaLand containers, as an

additional measure to protect critical equipment within adjacent nuclear facilities from blast damage and

potential projectiles. The stack was demolished well within the expected fall zone. Except for the

estimate of the pressure wave from the base of the stack, all assumptions and designated controls in the

hazard analysis were adequate and realistic, based on post-demolition monitoring data. As the stack

struck the ground and collapsed, the pressure wave was larger than expected and moved two large metal

SeaLand containers several feet. The containers were also damaged from small projectiles. However, the

B-9