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Technical Readiness Review of the n-3He Experiment

Technical Readiness Review of the n-3He Experiment. Seppo Penttila ORNL P-div At SNS Jan-10-2014. Technical Readiness Review of the n-3He Experiment. Overall schedule ES&H Radiological issues Tritium contaminated 3He gas. Seppo Penttila ORNL P-div. Schedule:.

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Technical Readiness Review of the n-3He Experiment

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  1. Technical Readiness Review of the n-3He Experiment Seppo Penttila ORNL P-div At SNS Jan-10-2014

  2. Technical Readiness Review of the n-3He Experiment • Overall schedule • ES&H • Radiological issues • Tritium contaminated 3He gas Seppo Penttila ORNL P-div

  3. Schedule: Flow of main tasks in the n-3He construction project • Design of components • close to be done • Procurement / fabrication of components • in progress • Testing / assembly / integration • outside beamline • Removal of NPDGamma • needs access to beamline • Installation in cave • as soon as possible • IRR process • completes the construction part of n-3He

  4. Main components of n-3He experiment 3He target/ detector RF Spin Rotator Lead gamma shielding 4 x preamp enclosures Supermirror polarizer Solenoid

  5. Construction and Installation tasks in level 1 Start disassemble NPDGamma Today IRR Preassembly

  6. Installation Gantt chart in level 3

  7. ES&H • Safety office : Paul Mueller • For us NPDGamma was significantly more complicated with respect to ES&H • No changes to PPS • No significant mechanical hazards • Normal electrical hazards; • 120-208 Vac and < 3kV HV • Electrical devices will be approved by SNS before use • 10-gauss magnetic field • 30-kHz well contained RF field • No cryogenics • Radiological issues; yes

  8. Removed NPDGamma components are slightly activated Activated especially are several Al beam windows and in some extend 48 CsI crystals. All the removed NPDGamma components will be staged and roped in bldg 8713 for survey, disassembly, and possible shipping.

  9. Dose Rate Calculations We have performed preliminary dose estimates with MCNP6 using Remec’s geometry, source term, and shielding package that he used for NPDGamma. • In NPDGamma neutrons are • converted to gamma rays • In n-3He experiment n-3He • capture doesn’t produce gamma • rays.

  10. Radiation Levels - n-3He has two modes of operation N-3He will have two modes of operation: Alignment with beam – no 3He in target Normal production with 3He target Dose rates have been studied for the both modes of operation

  11. The 1st task in commissioning is alignment of the detector to beam – beam profile need to be measured down- and upstream from the apparatus without target chamber and RFSR.

  12. Neutron dose rates with 3He

  13. Neutron dose rates with 3He

  14. Neutron dose rates with 3He

  15. Neutron dose rates with 3He

  16. Neutron dose rates without 3He

  17. Photon dose rates with/without 3He

  18. Photon dose rates with/without 3He

  19. Photon dose rates with/without 3He

  20. According to these preliminary dose rate studies, the radiation levels outside the shielding meet the SNS limit. We will complete the dose rate studies and then the SNS Neutronics Analysis group has to verify the results for IRR.

  21. Tritium contaminated 3He In experiment we are interested in reaction n +3He -> 3H + 1H T1/2 =12.3 yr

  22. How much tritium is produced ? BL-13 flux from guide For an upper-limit estimate for tritium amount at the end of the experiment: • After neutron guide neutron flux is 1011 neutrons/s • Supermirror polarizer reduces flux by 2 • 5x1010 neutrons/s enter the 3He target chamber • ½-lifetime of triton is 12.3 yr • 5000 h of production • Tritium activity in chamber will be 80 mCi corresponding to • about 1018 tritons = 1.4 micro mole = 4.2 micro gr

  23. We have to consider: • Accidental relies of tritium into Target Hall • During experiment sensing wires can break inside the chamber • we need to open the chamber; pump the contaminated • 3He to auxiliary container at SNS/HIFR/?? to fix the problem • When the experiment is over we want to recover 3He ($$) • at USA or • Transport chamber with tritium to Univ. Manitoba / Canada • for recovery.

  24. Chamber is a strong Al vacuum chamber with sst CF flanging – beam windows 1 mm thick Al. 3He gas in the chamber is at NTP. • We are in process with SNS to study issues such as; • What happens accidentally released gas • Possibility to pump contaminated 3He into a storage tank at SNS • Regulations for transportation of tritium contaminated gas inside USA • and across border to Canada. For IRR we will create a safety document to cover the tritium issues.

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