1. Radiation safety
(Adopting “low-surface contamination area” at the MLF Experimental halls)
To prepare for the upcoming high-beam-power op-eration of MLF, a new classiication of the radiation-con-trolled-area at the MLF experimental halls, “low-surface contamination area”, was adopted in November 2016.
Its purpose is to avoid surface-contamination problems caused by a sample, an environmental atmosphere, contamination and so on, and to expand the lexibility of the experimental conducted at MLF.
The low-surface contamination area is deined in the local radiation protection rule of J-PARC and is in-cluded in the 1st-class radiation-controlled area. In the area, a concentration of surface contamination equal to or lower than the standard value (0.04 Bq/cm2 for alpha-emitting radioisotopes and 0.4 Bq/cm2 for non-alpha-emitting radioisotopes) should be kept. If the contamination in the area exceeds the standard value, it should be removed immediately. An operation with any surface contamination in the area can’t be planned.
However, any accidental contamination is acceptable (and of course, it should be removed immediately). The limitation of gas and liquid used in the experiment is mit-igated. And challenging experiments can be conducted more easily. The low-surface contamination area is not applied to the BL11 experimental room and the 3rd ex-periment preparation room because the contamination is assumed during the experiment or the operation.
To introduce the low-surface contamination, a mon-itor for take-out articles and 2 hand-foot-clothes moni-tors were installed. More than 20 survey meters were prepared and can be used at each neutron instrument due to easy operation by users and stafs. Lockers were prepared in the locker room to reduce the number of ar-ticles brought to the experimental halls. Users and stafs can always take an article out of the radiation controlled-area, excluding irradiated articles and sample because of the installed monitor for articles that are being taken out. Periodic survey service (once a day) to take out large articles also started. In the summer maintenance period, the classiication of the radiation-controlled area at the experimental halls temporarily changes to 2nd class to make it easy to maintain the instruments.
(Radiological License Upgrade)
The two applications for radiological license up-grades in FY2016 were approved on September 27,
2016, and February 2, 2017.
Updated items on September 27, 2016:
(1) Change of the contamination survey areas for preparation to apply the 1st-class radiation-controlled area in the MLF experimental halls (2) Added storage and usage of several sealed
ra-dioisotopes (6 Cs-137)
(3) Preparation of the H-line installation of Muon beam line (change of shield structures)
(4) Change of the drainage equipment for radioac-tive liquid waste (position change of the con-nection to the tank lorry)
Updated item on February 2, 2017:
(1) Added gas folders in the of-gas system.
2. Chemical safety
The usual chemical safety checks of user-brought chemical materials, such as specimen and reagents, to evaluate their toxicity and the stability of their actual physical state – powder, solid, liquid or gas, were per-formed successfully by the chemical-safety team, along with approval of the actual materials for use by individ-ual beamline stafs. As a result, the experiments were performed without serious problems. Figure 1 shows a trend for the number of chemical materials for safety check. As for the form of the sample, solid was used most frequently, then powder, liquid, and gas. From the viewpoint of organic or inorganic matter, inorganic matter was used more frequently. In 2016, because of stably available beam time (approximately 153 days), the total number of chemical materials was increased, compared with 2015 (approximately 62 days), that was the highest number ever.
A Deuteration laboratory of P1 class has been un-der construction for several years. Currently, the rules for safety use are discussed, and it is scheduled for test operation from the next iscal year.
3. Alarm indication system for instrument condition monitoring
We started installing alarm indication systems on in-dividual beamlines in experimental halls. This system con-sists of signal line of equipment to monitor, connection box, controller, signal light and PC via J-LAN. The schemat-ic of the system is shown in Fig. 2. The status of the equip-ment of an individual beamline, collectively monitored, is displayed at a monitoring room by using this system.
One of the purposes of the system is to ensure an unattended operation of various kinds of sample envi-ronment equipment, for example, cryo-furnace, by ob-servation in the monitor room. Therefore, the burden on the users is alleviated for some of the equipment.
On the other hand, an application possibility of the sys-tem for unattended operation of the high sys-temperature furnace under maximum temperature of more than 1273 K is being discussed now. This year, the systems were installed at BL01, BL02, BL14 and BL22. Figure 3 shows the systems installed at BL01 and BL02.
The top red light indicates status of warning or nor-mal-operation by blinking or by lighting, respectively at any time. The orange light in the middle indicates status of caution of equipment, when the equipment signals potential malfunction, the light glows. The bottom light indicates the operation status, when the equipment is working in unattended operation mode, the light is
blue and when it is working in remote operation mode via IROHA2, which is the standard computational envi-ronment in MLF, the light turns green. A buzzer sounds when the status requires a warning.
Next year, the systems will be installed sequentially at other beamlines, including the muon beamline.
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Figure 2. Schematic of the alarm indication system.
Figure 3. (a) alarm indication system at BL01 and BL02, (b) signal light.
(a)
Blinking : warning Lighting : operation
Caution Operation status Blue : unattended operation
Green : remote operation Buzzer
(b)
4. Crane safety
There are 2 cranes in each experimental hall (ex-perimental hall No.1 and ex(ex-perimental hall No.2). These cranes are used to change the experimental setup dur-ing beam time and to perform summer maintenance by the technical stafs or constructors. Figure 3 shows the statistics of the total crane usage in both experimen-tal halls as a function of every month. There was a to-tal of 241 cases of use. The statistics for 2015 indicated high use in December and March, because of the per-formance of many experi-ments, based on the stable beam operation.
As usual, the safety measures and the effective schedules of crane usage were planned by the crane safety team. Also, the crane safety team checked monthly the mechanical sling, lifting sling, etc. and replaced the old ones with new ones when neces-sary. Furthermore, a crane operator, who wants to use the cranes in the experimental halls, needs to attend hands-on training by the crane safety team staf before the actual operation. As of the work team, according
to the rules, it must include a crane operator, slinging operator, and observer.
As a result, there were no serious problems with the crane operations.
M. Harada1, M. Ooi1, M. Sekijima1, K. Kawakami2, K. Aizawa2, A. Hori2, N. Kubo2, W. Kambara2, M. Sawabe2, K. Suzuya3, N. Kawamura4, Y. Sakaguchi5, Y. Yamaguchi5, and K. Soyama6
1Neutron Source Section Materials and Life Science Division, J-PARC Center; 2Technology Development Section, Materials and Life Science Division, J-PARC center; 3Neutron Science Section, Materials and Life Science Division, J-PARC center;4Muon Science Section, Materials and Life Science Division, J-PARC Center; 5Neutron R&D Division, CROSS-Tokai; 6Materials and Life Science Division, J-PARC center
Figure 4. Trend of the total crane usage in one year.
25
20
15
10
5
0
Number of crane usage
4 5 6 7 8 9 10 11 12 1 2 3
Month in-house staff
constructor
In Japanese Fiscal Year (JFY) 2016, the beam op-eration was planned to start on April 11, after the re-freshment of the cryogenic for the neutron moderator, which was performed from April 4 to 10. On April 4, a beam collimator placed at 3-GeV synchrotron malfunc-tioned causing a leak into the vacuum of the beam duct. It took until April 13 to ix the issue, then the beam operation for JFY 2016 started. Like in the previous is-cal year, the beam power was maintained at 200 kW to avoid damage to the mercury target. In February 2016, we replaced the target with a new one (Target #2).
Since this target was not equipped with a helium bub-bler to mitigate cavitation erosion at the target vessel, the beam power was lowered below 200 kW. The use of such beam power was decided in the previous plan, according to which we had to replace the target dur-ing outage period from June to October 2016. However, because the design and fabrication of next robust tar-get, which can withstand a high-power operation, took longer than expected, the target could not be changed in the summer as scheduled. To maintain the beam op-eration without the failure of Target #2, we decided to reduce the beam power to 150 kW for an expanded an-nual service from November to June 2017.
Table 1 shows the scheduled time and availability in JFY 2016 with a subtotal of records for the periods of 2016A and 2016B, which are switched on January 30. In JFY 2016, there were no severe failures, so the achieved availability was high at 90%. One of the reasons for such a high availability was the reduction of the beam power. The availability was very low in JFY 2015 due to
the failure of the target on two occasions. These records show that the development of a target with robustness to accept high-power beams is crucial to achieving such high availability. Another reason for that achieve-ment was that the cryogenic of the moderator was suc-cessfully cleaned up during the summer maintenance period. Figure 1 shows the trend of the beam power and its availability during JFY 2016. A signiicant failure was the malfunction of the timing system on June 21, which took a few days to ix and resume the operation.
Due to this failure, the daily availability was limited at the end of June. Since this failure occurred shortly after radiation inspection of the beam to extend the usage of the facility, this failure did not afect the schedule of radiation inspection. After November 2016, very stable beam operation was achieved.