上海光源剂量联锁PLC系统和故障记录

上海光源恒流注入模式需建立辐射剂量硬件联锁。剂量联锁系统以PLC为基础,采用一主站四从站的现场总线布局,通过语句表编程实现逻辑综合,并具有故障记录功能。程序采用字逻辑将状态输入与设定屏蔽位图进行比较,逐个模块地检查有无累积剂量超限输入和瞬时剂量超限输入,综合后经断开延时形成累积剂量联锁输出和瞬时剂量联锁输出。程序通过双字逻辑比较,得到新近发生的故障位置和故障时间,形成故障记录。故障记录功能有助于参与联锁探测器的故障定点诊断和维护。     

Dose rate distribution of photoneutrons in an ID beamline of SSRF: simulations and measurements

Photoneutrons, emitted by means of photonuclear interactions when gas bremsstrahlung interacts with beam- line components, can be another potential radiation source needed to be considered for shielding design and dose assessment of beamline. In this paper, simulations and measurements of photoneutrons dose rate at beam- line BL09U are carried out when Shanghai Synchrotron Radiation Facility （SSRF） running at Top-up mode （3.5 GeV, 235 mA）. A geometry model is constructed for the beamline BL09U with considerations of the scattering process of the major optical components. The model is compiled into Monte Carlo simulation code FLUKA to calculate photoneutron dose distribution. Measurements of the photoneutrons dose rate were per- formed by using Environmental Neutron Monitor （ENM）. Observation points were arranged uniformly along the inside and outside of the optical enclosure （OE） of BL09U. The calculation results agree with experiments within the measurements uncertainties. It is verified that photoneutrons dose simulation is reliable. The simula- tion and measurement methods can be applied to evaluate the neutron dose level of other beamline stations, and provide references for the shielding design of the beamlines at SSRF in the near future.