ACCELERATOR RADIATION SAFETY NEWSLETTER "Official Publication of the Accelerator Section of the Health Physics Society" Third Quarter 2000 Circulation: 293 Vol.9, #4 The web version may be found at: http://www.hps.org/iarpe/ OFFICERS President: James Liu, SLAC (james@slac.stanford.edu) President-Elect: Scott Schwahn, Jefferson Lab (schwahn@jlab.org) Past President: Joe McDonald, PNL (Joe.McDonald@pnl.gov) Secretary: Scott Walker, LANL (walker_lawrence_s@lanl.gov) Treasurer: Carter Ficklen, Jefferson Lab (ficklen@jlab.org) Newsletter Editor: Tracy Tipping, Macdonald Lab (tipping@phys.ksu.edu) Directors: Mike Grissom, SLAC (2001) (mikeg@slac.stanford.edu) Marcia Torres, ANL-E (2001) (mtorres@anl.gov) Bob Casey, BNL (2002) (casey@bnl.gov) Nolan Hertel, Georgia Tech (2002) (nolan.hertel@me.gatech.edu) Wes Dunn, International Isotopes (2003) (wdunn@intiso.com) Sayed Rokni, SLAC (2003) (rokni@slac.stanford.edu) ***From the President*** James Liu (james@slac.stanford.edu) Thanks to your participation and votes. Our section has a few people elected to serve as new officers. Meanwhile, the Section would like to extend the gratitude to the retiring officers, because of their efforts in leading our section into the year 2000. I am looking forward to a very interesting, and hopefully fruitful, year for the Accelerator Section. We intend to continue and/or accomplish several important tasks that have been undertaken so far: 1) Continue to invite Morgan Lecturer to address our Accelerator Session at the annual HPS meeting (we had Maurizio Pelliccioni of LNF in Philadelphia meeting and Hans Menzel of CERN in Denver meeting). 2) Nominate worthy candidates from our members for Society awards. This is to recognize their achievements and contributions and also to increase the visibility of our section. 3) Continue to pursue the joint organization of a training course on Accelerator Radiation Protection, which could be part of a series of summer schools held in Erice, Sicily (Vashek Vylet is leading the effort). In addition to a few interesting talks in Accelerator Session in Denver, we also has a mini-workshop consisting of six presentations (R. May of TJNAF, J. Drozdoff of TRIUMF, J. S. Bull of LANL, V. Vylet of Duke University, H. Kahnhauser of BNL and J. Liu of SLAC). The workshop concentrated on a single subject: the use of safety systems to protect the accelerator workers from prompt radiation hazard. The purpose was to exchange the ideas and experience among labs in tackling same critical issues that most facilities face. The speakers plan to summarize their presentations in a report hopefully to be shared with you in a future newsletter. We plan to continue this mini-workshop format (on other interesting and important issues) at the next HPS meeting. As part of the services that the Section provides to its members, I hope this activity would allow us to find consistent and scientifically sound approaches for the accelerator community. There are two other tasks that the Section is undertaking in order to provide a better service to the members. The first is to finish the Accelerator Section Standard Operating Procedures that Joe McDonald drafted this year and the other is to develop a section website. We need volunteers to help on the website and please contact Scott or me if you are interested. If you have any questions or comments, please feel free to discuss them with any officer. Without your support, the Section can not succeed. I hope we all can work together to accomplish the mission of the Section. ***From the Editor*** Tracy Tipping (tipping@phys.ksu.edu) And you thought you were done with me after the last issue of the newsletter... Due to a change in employment, Dawn Lobbes has stepped down as newsletter editor and I am putting together this issue until the newly appointed editor (Linnea Wahl from LBL (lewahl@lbl.gov)) can get her feet on the ground. So look for her handiwork next issue. And speaking of the next issue, it will be the Fourth Quarter issue of the newsletter (you may have noticed that this issue is labeled the Third Quarter 2000 issue). The Accelerator Section Board has decided to decrease the frequency of publication of the newsletter to four times per year. So you can look forward to quarterly issues of the newsletter in March, June, September, and December of each year. ------------------------------------- News from Correspondents ------------------------------------- ***News from Jefferson Lab*** Scott Schwahn (schwahn@jlab.org) At Jefferson Lab, we continue to work on implementation of DOE O 435.1, the Radioactive Waste Order. We have competitively bid for companies to provide the service of taking our "waste" and disposing of it in the most economic and environmentally friendly manner. We have selected a vendor finally and will be characterizing and sorting our waste, completely eliminating current inventory by July 2001. Most of what we would now call waste is contamination control scrap, protective clothing, and filters that are contaminated primarily with Be-7. Much of that waste is likely no longer contaminated at all since the half-life of Be-7 is only 53 days. However, we are also having to make the judgment calls that any machine components that are unlikely to be reused will have to be considered waste as well. We are seeking the cooperation of individuals from the experimental halls and the accelerators to identify whether or not items will be reused before they leave the areas and to periodically check their inventories to ensure that we don't hold onto items that are unlikely to be reused. On another subject, we recently underwent our biennial Radiation Control Group peer review. Three days of review by three well-respected external colleagues, one internal senior lab manager, with several observers, resulted in a "Superior" rating, the highest available rating. Two years ago, we rated an "Excellent". We are obviously pleased with the results. We attribute our success to a small but dedicated and hardworking group. Jefferson Lab has been awarded a large chunk of the Spallation Neutron Source (SNS) work, which continues to add load to all of the Jefferson Lab staff, including RadCon. We will soon be considering how to obtain a decommissioned commercial accelerator in New York, and how to set it up and run it here. It will involve substantial work on the part of our technologists to assist in the movement, and of our professional staff to consider the shielding and other safety requirements. LAST MINUTE NEWS FLASH The Thomas Jefferson National Accelerator Facility's Director, Dr. Hermann Grunder, Accepts Directorship of Argonne National Lab, effective November 1, 2000. Details may be found at: http://www.jlab.org/grunder.html ***News from CAMD*** Lorraine Day (day@lsu.edu) CAMD, the J. Bennett Johnston Sr. Center for Advanced Microstructures and Devices, a part of Louisiana State University houses a 1.5 GeV synchrotron ring and 200 MeV Linear Accelerator. Recently, CAMD underwent a review of its radiation safety program. Members of the review committee were Tom Dickinson (NSLS), Bob May (Jlab) and Rick Donahue (ALS) - thanks guys for a job well done. CAMD has recently commissioned its first wiggler beamline for operation. The Wiggler has a unique, patented design (by Ben Craft - deputy director of CAMD) and built by the Budker Institute in Russia. The 7.5 T, 3-pole wiggler is capable of producing 60 keV photons. Next week, we will commission the new X-ray tomography beamline which is a white beam experiment in air. A second beamline off the wiggler is nearing completion (the Normal Incidence Monochromator or NIM beamline). In September, the first components of the Wiggler - Protein Crystallography beamline, built by Oxford Instruments begins to arrive. It promises to be a busy but rewarding time for all involved. In preparation for the protein crystallography work, CAMD is gearing up toward 24 hour operation. We are instituting new policies and procedures to deal with handling all this beamtime with a limited staff. Our staff remains at around 40 individuals including all accelerator staff, vacuum staff, engineering, scientific staff, support staff, computer and office staff. We have ambitious plans for such a small unit but work well as a team. ***News from APT*** Michael Duran (duranma@lanl.gov) LEDA Accelerator at Los Alamos Reports Experiences with First 100 mAmp Proton Beam Scientists and engineers from several US national laboratories and industries have put together an accelerator-based system design that has been extensively reviewed. Those reviews have concluded that an accelerator production of tritium (APT) system will easily, safely, and adequately meet the nation's tritium needs. To prepare for the possible construction of this vital system, national laboratory partners - Los Alamos, Brookhaven, Livermore, Sandia, Thomas Jefferson, and Savannah River - have completed or are completing several important technology demonstrations and plant-prototype developments. Scientists are verifying the tritium production efficiency of APT and candidate materials for target construction using high-power beams in the Los Alamos Neutron Science Center (LANSCE). They have built and are operating a full-power, low-energy engineering model of the accelerator to substantiate its long-term performance. The low energy demonstration accelerator (LEDA) is a prototype of the low-energy, front-end of the linear accelerator (linac) to be used in an APT plant. LEDA is currently capable of producing a proton beam of 6.7 MeV, and a nominal current of 100 mA, at sustained continuous operation. LEDA consists of a proton injector, a radio frequency quadrupole (RFQ) accelerator, a rf power system, a diagnostic beam line, and a beam stop. Beam diagnostics and a computer control system are also included as part of the LEDA facility. In December 1999, the LEDA operation's goal of sustained beam delivery at 100 mA for 8 hours was successfully achieved. ESH-1 Operational Health Physics at LANSCE has completed a series of measurements to characterize and validate predicted dose rates and contamination levels included in the LEDA Safety Assessment Document (APT-DOC-011). An excerpt from the LEDA SAD: "The only radionuclide inventory of any significance will be the activation products in the beam stop. No radioactive material will be brought into the facility, and the activation of air, water, and other parts of the beam line will be negligible relative to the beam stop activation." LEDA uses a Ni-201 conical shaped ogive beam stop that is enclosed by a 30" water shield. The calculated radionuclide inventory discussed in the LEDA SAD is minimal from a risk analysis point of view, but it is not negligible from an operational viewpoint. ESH-1 found V-48, Mn-54, Co-56, Co-57, and Zn-65 contamination inside the RFQ beam pipe. A large area swipe was taken and the radionuclides were identified by gamma spectroscopy analysis. Appropriate radiological contamination controls have been implemented for linac maintenance activities. There were also unanticipated elevated dose rates near the downstream end of the RFQ, at the intersection with the high-energy beam transport. The dose rates ranged from 1,000 mrem/h 12 hours after beam off, decaying down to about 150 mrem/h after 6 weeks. A portable HPGe detector was used to characterize the external RFQ nuclide makeup. The activation nuclides measured outside the RFQ appear to be similar to that found in the swipe sample, with exception of Fe-59 and Co-60. In both measurements, Co-56 was most dominant, relative to the other identified nuclides in both the swipe and external gamma spec analysis. LEDA SAD Table 4-11 indicates a significant level of tritium (2.6E6 pCi/l) will accumulate in the beam stop cooling water, during a 6-month continuous production period. We have not found detectable levels of tritium in the beam stop cooling water or in the shielding water. We note that the LEDA production period was very different than the 6-month continuous period used in the SAD calculations. LEDA operated regularly during that last quarter of 1999 and delivered a total of 21,335 mA-h of proton beam. LEDA SAD Table 4-3 lists the activation gamma dose rate from the beamstop after a 6-month continuous production period. The table indicates 6 mrem/h outside the side wall shield after a 1-day period of decay and 1 mrem/h after 7 days. ESH-1 measured a maximum dose rate of 3 mrem/h at contact on the outside of the water shield wall after a 5-day period of decay. Which was in pretty good agreement between the calculated and measures dose rates after the short-lived radionuclides have decayed. Six TLD dosimetry plants were placed around the LEDA accelerator boundary to monitor radiation levels in occupied areas (Figure 1: "LEDA TLD Plant Locations" may be seen at http://www.hps.org/iarpe/pics/ledamap.gif). The plants were exposed to 10,584 mA*h for a total of 136 hours, resulting in a 78 mA average beam current. The plants were placed in the LEDA tunnel for a period of approximately 1400 hours, and were retrieved after the beam was turned off, on April 17, 2000. The TLD plants were placed on polyethylene phantoms to simulate whole-body dose response. An attempt was made to place the TLDs at locations that were close to the SAD based points. Monte Carlo (MCNP) radiation transport calculations were performed as part of the SAD. The MCNP model was based on LEDA phase one (6.7 MeV, 100 mA) operating parameters and anticipated tunnel geometry. The TLD dose results are: TLD Plant Location Gamma Neutron Total Dose (mR/h) (mrem/h) (mrem/h) MPF-365 Lobby 0 0 0 East Waveguide Shaft 0 0 0 West Waveguide Shaft 0 0.1 0.1 LEDA Roof Access 0.2 0.9 1.1 East Rollup Door 0.3 5.6 5.9 West Rollup Door 0 1.0 1.0 The LEDA SAD (Figure 4-4) calculated prompt dose rates are listed below: Location Calculated Prompt Ratio of Calculated Dose Rate (mrem/h) to TLD Dose Rate East Waveguide Shaft 2 undefined West Waveguide Shaft 3 31 LEDA Roof Access 1 0.9 East Rollup Door 70 12 West Rollup Door 1 1 Comparison of the data indicates that there were some differences between the MCNP calculated and TLD measured values. For the most part, the calculated and measured data were comparable at the low dose rates involved. However the East Rollup Door comparisons raises some level of question. The calculations are being reviewed for conformance to as-built drawings, as part of the feedback process. In 1999, the number of individuals working at LEDA who were issued dosimetry ranged from 64 to 77. Approximately 10% of these individuals received measurable dose on their dosimetry. The average dose recorded was 8.4 mrem, due exclusively to neutron exposure. The maximum dose recorded for an individual was 19 mrem. In conclusion, the measured radiation levels at LEDA involved only a few surprises. The contamination levels found inside the beam pipe and the upgrade and maintenance activities at the end of the RFQ were the major operational health physics concerns. The LEDA dosimetry results indicated that adequate hp controls were in place and radiation doses were being maintained ALARA. ------------------------------------------------------------ Accelerator Section Executive Board Meeting 6/26/00 ------------------------------------------------------------ Attending: President: Joe McDonald President-Elect: James Liu Secretary: Scott Schwahn Treasurer: Carter Ficklen Board Member: Nolan Hertel Board Member: Mike Grissom Board Member: Wes Dunn Secretary-Designate: Scott Walker Absent: Past-President: Steve Musolino Newsletter Editor: Tracy Tipping Board Member: Bob May Board Member: Keith Welch Board Member: Marcia Torres The meeting was called to order by President Joe McDonald. - Carter brought us up to date on the finances of the Section, including the interest that we received from Burk & Assoc. - Scott S. suggested a marketing effort among the states for increased membership. It would involve contacting each of the states for an address list of license holders for non-medical radiation generating device RSO's. The idea was met with general approval, and Scott S. indicated that he would continue the process. - Carter updated us about efforts to remove accelerators from the Nuclear QA requirements of the Price-Anderson Amendments Act (PAAA). Brookhaven quantified that the Nuclear QA efforts would add about 7% to the cost of operation. - Scott W. updated us on ANSI N43.1 efforts. While they are still having difficulty finalizing the definition of an accelerator, they have completed drafts of Chapters 3,4,5, and 6. They are about 1/3 complete with Chapter 7 and 1/2 complete on Chapter 8. They hope to have a draft standard complete by the next annual meeting in 2001. It may possibly be a standard by 2003. He indicated that the ANSI N43 Chair is pleased with their quality of work. They started the process in 1996. - Joe suggested the possibility of making it an ISO standard. - Nolan suggested that the Past President should be the Chair of the Nominations Committee and that he/she in that capacity should ensure that one Board Member be selected for the Nominations Committee. All were in agreement and it was decided to include that role in the Officer Standard Operating Procedures that Joe drafted this year. - Scott S. was appointed as Parliamentarian for the upcoming year. - Joe indicated that the Erice conference was slow going. The ways of getting European Union (EU) support are convoluted and constantly changing. Vashek Vylet continues to work on it. - Scott S. updated us on the method for allowing non-affiliated Section members. The process is relatively simple. A brief letter can be sent to Burk & Assoc. with a $10 check and it will happen. They will have none of the benefits of HPS membership, but will be full members of the Section. They may not, however, serve as Officers. - Scott S. suggested that we consider setting a budget for the upcoming years in conformance to our bylaws. The idea was met with general comments doubting the need for such an effort, as we rarely spend money. No consensus was reached. - An interest in presenting an HPS Summer School was presented. We had suggested this a couple years ago to the Continuing Education Committee and no one seemed to know what happened to the idea. Scott W. agreed to attend the Wednesday meeting of the Continuing Education Committee and see what is happening. - James suggested a website for the Section with a current update of Section membership and as a means to recruit for membership. All agreed it would be a fine idea, with no volunteers to shepherd the process. 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