[DOE LETTERHEAD]
Savannah River Operations Office
November 23, 2005
The Honorable A. J. Eggenberger
Chairman
Defense Nuclear Facilities
Safety Board
625 Indiana Avenue NW, Suite 700
Washington, D.C. 20004
SUBJECT:
Design Approach for Providing Performance
Category 3 (PC-3) Confinement for the Salt Waste Processing Facility (SWPF)
Dear Mr. Chairman:
In your letter of August 27,
2004, you requested the Department take action to provide consistent and adequate
natural phenomena hazard (NPH) design guidance where systems, structures and
components are relied upon to confine radioactive materials. In the absence of clarified guidance, your
letter requested that the Department assign a NPH performance category (PC)
designation of PC-3 where safety analysis for the Salt Waste Processing
Facility (SWPF) determines confinement of radioactive materials is necessary
for worker safety. Your letter also
recommended consideration of the use of a safety-related active ventilation
system at SWPF similar to the confinement concept applied at the Highly
Enriched Uranium Materials Facility (HEUMF) at the Y-12 National Security
Complex.
In response to your concerns,
the Department considered several options for assuring reliable confinement of
SWPF high-hazards materials in the event of an earthquake or other natural
phenomena. These options included use of
a local, safety-related PC-3 confinement barrier (e.g., piping) housed within a
PC-3 building; use of a local, safety-related PC-3 confinement barrier housed
within a PC-2 building; and use of a safety related PC-3 active ventilation
system housed within either a PC-2 or PC-3 building.
The Department has concluded
that adopting a local, safety-related PC-3 confinement barrier housed within a
PC-3 building to be the most prudent course of action for SWPF. Where safety analysis indicates confinement
barriers are necessary for worker protection, the SWPF Preliminary Design will
be revised to incorporate a PC-3 designation for safety-related piping, process
vessels, and other components that would provide a local confinement barrier. Portions of the facility housing
safety-related PC-3 local confinement barriers will also be designated as PC-3
and designed to resist natural phenomena events. As a defense-in-depth measure, safety-related
active ventilation systems will be provided to protect workers from process
upsets involving a significant release of radioactive material due to non-NPH
events (e.g., tank overflow or spills). Since the SWPF design will now incorporate local
safety-related confinement barriers designed to resist natural phenomena (i.e.,
PC-3), safety-related ventilation systems will not have to resist natural
phenomena to protect facility workers. The confinement strategy described above is similar
to the confinement concept applied at HEUMF.
This enhanced approach for SWPF
confinement design provides additional margin for safety and is anticipated to
adequately address the DNFSB’s confinement issues with the SWPF. Actions to implement this approach were
approved by the Deputy Secretary of Energy on November 21, 2005. I would like to thank you and your staff for
their assistance in helping to resolve these issues. If you have any questions, please contact me
at (803) 952-6337.
Sincerely,
Jeffrey M. Allison
Manager
cc: I. Triay, EM-3
M. B.
Whitaker, Jr., DR-1