Radiation monitoring & ALARA
Armouring Armenians17 May 2010
The Middle East’s only operating commercial nuclear plant, Armenia NPP, has begun a programme to reduce worker doses. A new European Union-funded programme will also help. By Aida Avetisyan and Vovik Atoyan
The Armenian Nuclear Power Plant (ANPP), also known for the nearby town Metsamor, is the only nuclear power plant in the region. It consists of two VVER/440/270 units (that is a modified, seismic VVER/440/230 design). Unit 1 started its commercial operation in 1976 and unit 2 in 1980. Both units were shut down shortly after the 1988 Spitak earthquake. Recommissioning works were performed from 1993 to 1995 and in November 1995 unit 2 restarted operation. At this moment the ANPP unit 1 is in long-term shut down.
Radiation safety norms and the radiation protection rules for the regulation of safety and control of employees, public, medical exposure and the environment were put into force in 2006.
These regulations state the dose limits for the staff, for the public and for the medical exposure (guidance levels). The limits are in line with IAEA safety standards.
For the implementation of the limits, as well as for the fulfillment of the principles of optimization of doses and related radiation risks, the radiation safety rules stipulate the requirements on radiation protection of the workers and the safety of the sources. The more detailed radiation protection and safety requirements are stated in the special regulations for the nuclear facilities, including NPPs.
ANPP has more than 873 staff under the radiation safety control. Most of them (excluding the shift staff) are not permanently at work in a controlled area, and could be involved during outages or maintenance or refuelling activities at ANPP.
A special order of management has established an ALARA committee that has adopted an implementation programme. This plan includes the technical and organizational measures as well as the dose planning approach, which is periodically reviewed by the radiation protection department and management of ANPP.
General dose reduction guidelines were established. They include, for example, ensuring decontamination of areas before and after maintenance work, minimising the presence of unnecessary personnel in affected areas, segregating tools used in affected areas, providing affected staff with dosimeters, and other rules.
During maintenance activities personal protection equipment is to be used:
• Isolating protection equipment (pneumatic suit, pneumatic helmet and in particular cases self-contained isolating equipment) should be used during activities when the room air radioactive contamination exceeds the allowable levels more than 200 times. In more common cases, respirators are used.
• For hand protection, rubber gloves resistant to chemical agents specific for this production site are used combined with cotton gloves. The additional PPE is taken off in such a manner so that not to contaminate the main protective clothing and protective shoes. First removed should be the plastic protective clothing and protective shoes, then the gloves and last the respirators.
Despite the plans, some managerial and financial problems still exist for the improvement of occupational radiation protection and for modernization of radiation control system. In particular, there are some organizational gaps in the work of different levels of managers.
A new programme for modernization of the system is already approved by the management of ANPP and is due to be finished by 2011. The European Commission published a tender to upgrade the NPP’s radiation protection measures in August 2009, through its Technical Assistance to the Commonwealth of Independent States (Tacis) programme.
The tender covers a radiation protection upgrade that includes a new package of at least 900 thermoluminescent dosimeters, computer software and hardware to manage them, entry/exit terminals, hand/foot and whole body contamination monitors and mechanical turnstiles.
In 2008, general repair and maintenance activities (chemical cleaning of reactor vessel, non-destructive testing of reactor vessel and eddy current control of steam generator tubes with cutting damaged tubes) were planned and performed at ANPP. The doses for 2008 were increased slightly and influenced dosimetric trends.
The planned exposure doses for repair and outage were agreed with regulatory body. The planned collective dose before outage for 2008 was 1.58 man*Sv. The real collective doses during the outage were 0.78 man*Sv.
Distribution of main doses within different departments of ANPP was:
• 61.8% for the repair work
• 16.1% for decontamination work
• 6.2% for non-destructive testing
The remaining percentages are distributed within other departments of ANPP. Doses recorded in 2009 were lower than 2008.
Aida Avetisyan, Armenian Nuclear Regulatory Authority, Head of Radiation Safety Section, 4 Tigran Mets, Yerevan, Republic of Armenia. Vovik Atoyan, Armenian Nuclear Power Plant. This article is an edited version of a paper given at the 2009 International ISOE ALARA Symposium in Vienna, AustriaRelated ArticlesContract awarded for new reactor at Metsamor World survey part 2: Russia and CIS Armenia hopes to delay shutdown of Metsamor plant Armenia hopes to delay shutdown of Metsamor plant EU finance for Metsamor closure Russia takes control of reactor Russian fuel arrives at Metsamor