This is a United States Department of Energy funded project, which constructed a new Health Physics Instrumentation laboratory (HPIL) at the Idaho National Laboratory (INL) near Arco, Idaho. The building is approximately 16,000 square feet and cost about 13 million dollars. The building is used to calibrate radiation detection devices. Most of the devices are hand held Geiger counter type instruments. To ensure the accuracy of calibration work, special conditions must exist. The building internal air temperature must be maintained in a very narrow range (+ - 2 degrees F), humidity must be tightly controlled and heavy concrete shielding walls and roofs are required. Any material used for support of instruments and equipment must have a low atomic mass. Therefore aluminum and plastic are used extensively.

This facility will calibrate instruments for the INL with some minor calibration work to be done for other government agencies including NASA.

The existing HPIL laboratory was located in a World War II bunker where battleship guns were test fired. Temperature control was very poor. There were many national electric code infractions. There is no humidity control. The low scatter laboratory, which was installed in a high-bay garage, did not have adequate radiation shielding. The roof was leaking. Some areas of the building were radioactively contaminated from prior use of the building as a dosimeter laboratory. The floor plan layout was inefficient and problematic. Vermin infested the basement and posed a Haunta virus threat.

This facility is essential to INL operations.

There had been a completed conceptual design of the facility during 1992. However it was too expensive for available funding. At the direction of the Idaho Falls Department of energy, the design team looked at modification of two existing facilities rather than construction of a new facility. Preliminary floor plans were prepared and estimated. The costs for the modifications turned out to be greater than that of construction of a new facility. Therefore it was determined that a new facility should be constructed. Costs of land were not considered in the cost comparisons as the land is free and the area where the new lab was to be built had already had a previous temporary office building removed.

During the design a 500-year flood was considered and the building floor elevation was raised approximately 3 feet. Earth berms around the facility were created and covered with weed check and 3 to 5 inch round river rock. The maintenance managers did not want grass that would have to be mowed and watered. The stone has worked well except when outside light bulbs need to be replaced. The surface of the stones make an uneven surface for a ladder base.

The 1992 laboratory plan was revised and estimated. Several iterations were involved in order to maintain required functions and reduce the building size. Many meetings with the building managers were required. Working with the cost estimators, It was determined that the least expensive enclosure for the administrative area was to use a metal building. The construction labor costs at the INL are very high and this type of structure minimizes installation time.

The use of metal building for enclosing the administrative area posed a problem because the design standards for the INL require that a 3 in 12 slope be used for metal roofing. The width of the floor plan created a very large volume above the one story floor plan due to the roof slope. It was determined that the air handlers for the facility could be place in a room under the ridge of the roof to take advantage of the additional space.

The low scatter lab was investigated for cost savings and improved function, as it is most expensive single item in the facility. All current low scatter lab facilities use a 40-foot cube for room enclosure shape. However it was learned that there is more backscatter in these facilities than is desirable. Backscatter is reverberating radiation that makes it more difficult to calibrate the instruments and requires a modifying equation that takes into account the bouncing streams. Since the waves of different sources (six different types are used in HPIL) behave differently the accuracy of the calibration suffers. Working with a nuclear engineering consultant it was determined that a sphere 38 feet in diameter would be the perfect shape, but would be very difficult to build and very expensive to form. The walls are 3 foot thick (144 lbs per cubic foot) concrete. It was determined that the most feasible shape would be a cylinder 38 feet tall with a similar diameter. Slip forming of the cylinder could be accomplished and it would be at least $6,000 dollars less than conventional forming a similar cube. It would also allow making a monolithic placement of the concrete to eliminate any cold joints that may allow radiation streaming.

Currently this is the only cylindrical low scatter lab in the world. Actual use of the facility has proven the principle. The backscatter is greatly reduced for all sources.

The gamma well calibration system was investigated to determine a better design than existing. Currently virtually all gamma wells in use are 12-inch diameter pipes of painted carbon steel. The paint flakes off after years of use and rust occurs creating a dark surface. Occasionally the sources slip off the tracks and have to be retrieved with specially designed tools. It is especially important that visibility to the bottom of the tube is maintained. The design Used on HPIL used specially finished unpainted stainless steel pipes to promote visibility, should a source become stuck. They are 18 inches in diameter to make stuck source retrieval as easy as possible.

Procurement of the calibration systems, computers and software was researched by investigating previous facilities constructed in the U.S. Specifically the lab constructed at Savannah River, South Carolina. In that project all of the calibration systems were placed in the construction contract under the control of a general contractor. It was determined that the calibration supplier was required to do several things that could have been done better due to the contractual arrangements. It was determined that on the HPIL project the calibration system would be a separate contract so that the very best system would be provided. This caused more work on the part of project management in coordinating the building construction with the calibration systems but the resulting system is state of the art and works extremely well.

The facility was constructed on schedule and approximately $550,000 dollars under budget. The building managers are very happy with the resulting facility and have requests from other national labs for additional calibration work. Idaho State University considering using the facility for other unforeseen nuclear engineering testing.

Use of the metal roofing at a 3 in 12 slope was made to work for this design but It has been learned that a low slope roof of single ply EPDM could have been used on the metal building. The attic air handler room was expensive to construct. It would have been less expensive and simpler to construct on grade.