(d) The exhaust systems shall run continuously. Airflow switch shall
provide an interruption in airflow with audible and visible alarms
located locally as well as at the Engineering Control Center.
4.7 RADIOACTIVE IODINE
4.7.1 GENERAL
The procedure, to calculate the amount of exhaust air quantity to
dilute the concentration of radioactive iodine material, is similar to
the Xenon gas. See Article 4.12 for details.
4.7.2 MAXIMUM CONCENTRATION
The Maximum Permissible Concentration (MPC) of the radioactive iodine
in the exhaust air discharged into unrestricted areas, averaged over a
period of one year, shall not exceed:
(a) Iodine 131: 1 X 10-10 Micro-Curies Per Milliliter of Volume
(b) Iodine 125: 8 X 10-11 Micro-Curies Per Milliliter of Volume as
outlined in the Code of Federal Regulations (CFR), Part 20, Appendix
"B", Table II of the Nuclear Regulatory Commission.
4.7.3 EXHAUST AIR SYSTEM
Provide a dedicated exhaust system to dilute and dispose radioactive
iodine material. Establish the amount of activity used in the space
from the medical center personnel and calculate the exhaust air
quantity by using the equations outlined in Article 4.12. The
calculations should be reviewed and approved by the VA Radiation Safety
Officer. The exhaust air should be discharged at the highest point
above the building. The exhaust air shall be picked up either through
the space or a H3 hood.
4.7.4 EMERGENCY POWER REQUIREMENTS
The exhaust system shall be on emergency power.
4.8 TELEPHONE EQUIPMENT ROOMS
4.8.1 GENERAL
Assume sensible heat gain to the space at the rate of 1350 W (4,500
BTUH) per 100 lines of telephone service. Estimate the cooling
requirements on the basis of the present plus future capacity of the
telephone service. Coordinate this information with Telecommunications
Support Service of the VA at the Headquarters.
4.8.2 INDOOR DESIGN CONDITIONS
Summer and Winter: 19 to 23 degrees C (65 to 75 degrees F), 40 to 60
percent RH
4.8.3 EMERGENCY POWER REQUIREMENTS
HVAC equipment serving telephone equipment rooms shall be on emergency
power.
4.8.4 HVAC REQUIREMENTS
Wherever possible, use the building environmental air-handling unit, as
the primary source, to serve the Telephone Equipment Room. Provide
individual room temperature control. In addition, provide a 100 percent
HVAC DESIGN MANUAL
4-3
HVAC REQUIREMENTS FOR UNOCCUPIED AREAS
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