We are committed to maintain a comprehensive radiological protection programme safeguarding all our employees and contractors and the general public against the hazards of ionising radiation arising from operating our plants. Our approach is to ensure, as a minimum, compliance with all applicable regulations, to emulate best nuclear industry practices and continuously improve our practices and to work to a common fleet standard. We strive to ensure that any radiation exposure to ionising radiation is kept as low as reasonably practicable (ALARP), to reduce individual and collective radiation doses and prevent any worker exceeding a statutory radiation dose limit.
Radiological protection is identified as one of the 15 principle processes within our Company.
We have dedicated radiological protection personnel and a radiological protection programme in place to set standards, measure compliance and drive continuous improvement. Many of the improvements that have been introduced over the last seven years would not have been possible without management support and financial investment in the radiological protection programme.
Collective radiation exposure (dose)
We operate procedures to minimise, reduce and control the radiation doses received by all our employees and contractors at all of our nuclear power stations. Any worker required to enter a radiological controlled area is issued with an electronic personal dosimeter which measures radiation dose and warns the wearer if pre-determined dose levels are exceeded. Radiation dose is measured in units of milliSieverts (mSv). The legal dose limit is 20 mSv per year. We operate to a Company Dose Restriction Level of 10 mSv.
In calendar year 2013, the average individual dose received by all our employees and contractors on our sites was 0.053 mSv and 0.066 mSv respectively.
The highest individual dose received on our sites was 4.622 mSv in calendar year 2013 (this is 23% of the legal limit). This dose was received by an AGR in vessel inspector who supported the Heysham 2 standpipe liner replacement and is below the project dose constraint of 6 mSv. In AGR vessel outage years we incur higher individual dose due to the nature of the work being performed.
Radiological protection performance on EDF Energy (NG) sites has continued to exhibit year on year improvement with respect to radiation exposure. The principle reason being the governance steps taken for work associated with the highest impact on Company Collective Radiation Exposure. Simulator training facilities, procurement and use of improved equipment, coupled with a highly trained and experienced workforce, has resulted in better than anticipated improvements in 2013. The most significant reductions have been for AGR reactor in-vessel work at Heysham 2 where a replacement of a standpipe liner was required. The collective radiation exposure at Sizewell B (PWR) in 2013 is slightly greater than predicted due to additional significant emergent work during the 2013 refuelling outage.
Company radiation exposure results show considerable year-to-year variation depending mainly on the number and location of reactor outages and the nature of the work undertaken in those outages. In comparison normal operational doses are low. The three year zero harm Company Collective Radiation Exposure result was better than target. This provides realistic appraisal of dose trends over time as it helps to smooth out the variations of cyclical outage performances. By comparison with other Nuclear Operators the radiation dose received by workers at EDF Energy NG is relatively low; primarily due to the design of the AGRs, good PWR dose performance and excellent control of all high dose work performed across the Company. EDF Energy NG applies stringent procedures to reduce to a minimum and check the radiation doses received by staff and contractors on all existing sites. Improvements have been made in dose predictions for AGR in vessel work and rigorous ALARP Committee oversight has been exercised.
The three year average yearly WANO Collective Radiation Exposure (dose) for EDF Energy Generation (NG) at the end of 2013 was 0.076 manSv/reactor versus a target of 0.079 Sv/reactor. We are striving to show a continuous improvement (reduction) in this key performance record as demonstrated by the annual improvement in our performance over the last 3 years.
Dose to the most exposed members of the public
We are required to assess the radiation dose to the most exposed members of the public in the vicinity of our sites using the results of environmental monitoring. However, this does not distinguish between the impact of our discharges and those of neighbouring operators. Discharge modelling is used to make a conservative assessment of the impact of our discharges on the local population; the assessment for the three years 2011 to 2013 is given below.
Doses to the public are a very small fraction of the legal limit and the average radiation dose due to natural background in the UK. The maximum dose received over this period (0.006 mSv in 2013) is equivalent to the natural radiation dose received during a single flight from London to Rome.
The consistent level of very low public dose from 2011 to 2013 is evidence of the company’s successful efforts to employ best practicable means to minimise the impact of its discharges on the public (a formal requirement of our discharge permits).