UCN Phase 2 Design Status

1. UCN Phase 2 Design Status September 10, 2002

2. Bulk Shielding Target Crypt Cryogenic Insert Target Insert UCN Port Beam Window Cooling System Radioactive Effluents Design Components

4. Bulk Shielding Design • To include steel and concrete around the moderated target sufficient to maintain dose rates for 10 μA below: • 0.1 mrem/h on the experiment floor • 100 mrem/h above the shielding • 5 mrem/h in corridor to Line B tunnel • Anticipate target will normally be operated at less than 5 μA

5. Bulk Shielding Design Continued • Provided 4.5 feet of steel and 3 feet concrete above target crypt, dose rates locally on the order of 10’s of mrem/h above the shielding for 10 μA • Dose rates on the experiment area floor average ~0.08 mrem/h for 10 μA primarily due to scattering from roof, walls, air, and ground

6. Bulk Shielding Design Continued • Preliminary calculations of bulk shielding dose rates conservatively based on assumptions that proton beam completely interacts in tungsten but that the tungsten provides no shielding • Target crypt is assumed to be filled with graphite

9. Target Crypt Design • Crypt will be lined with aluminum and filled with graphite • Include a 6-foot graphite beam stop • Tungsten target will be centered in a 27-inch cube of beryllium • Above the target a 13-inch diameter penetration will receive the cryogenic insert

10. Target Crypt Design Continued • Crypt will receive target insert from the side • Beam stop cooling is being included in the design and coolant lines will be routed to system components to be installed on top of bulk shielding

12. Cryogenic Insert Design • Will be inserted into the target crypt from the top • Lower end will contain a 4 cm thick liquid deuterium region, not to be credited in the shielding design • Above the deuterium to an elevation above the UCN port will be a vacuum chamber

13. Cryogenic Insert Design Continued • Height of the vacuum chamber is yet to be determined but will be based on trade-offs between experiment impact and plug shielding requirements • A 3-inch penetration will be required for service and instrumentation lines • Insert design will include shielding above the vacuum chamber but additional shielding may be necessary above the insert

15. Target Insert Design • No engineering drawings have been drafted but design is expected to include: • Consist of shielding equivalent to the bulk • Include at least one step to minimize streaming • Have small diameter penetrations will multiple bends for target coolant lines • Coolant lines to be routed to cooling system components installed on top of bulk shielding • Will facilitate remote removal and transfer of target to a shielded cask

17. UCN Port • Will lie in a 6-inch square penetration in the bulk shielding, 4 feet above the beamline elevation, with two 45° bends • Outer pipe will have an external diameter of 4 inches • Plan to line penetration around the UCN pipe to minimize radiation streaming

18. Beam Window • Mates with hole in the target crypt wall • Includes cooling lines that will be routed to system components installed on top of bulk shielding • Will be removable with beam line through bulk shielding by retracting into the Line B tunnel

20. Cooling System • Design only in conceptual stages • Evaluating use of a helium gas primary loop for the beam window, target, and beamstop • Plan to installed cooling system components on top of the bulk shielding at the south end

21. Radioactive Effluents • Target crypt void space is minimal and to further minimize air activation: • Plan to provide a helium gas supply to the target crypt with an exhaust into the Line B tunnel • Plan to install a sealed, helium filled beamline segment between the beam window and the target

22. Radioactive Effluents Continued • Target crypt will include a drain in the bottom with piping to the a Line B radioactive waste drain, regardless of whether or not all primary coolants are helium