Safety Case for the Rakovica Radioactive Waste Storage Facility /
Baseline Safety Case /
RPC /
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Contents
1.The context of the Safety Case
1.1The generic Safety Case context
1.2B&H radiation protection framework
1.3B&H radioactive waste management policy and strategy
1.4The purpose and scope of the Safety Case
2.Strategy for safety
3.Description of the Rakovica Facility, Facility operation and waste
3.1Description of the site
3.2Description of the facility
3.2.1General facility description
3.2.2Buildings layout
3.2.3Building structure
3.2.4Building base slab/floor
3.2.5The doors
3.2.6Finishes
3.2.7Shielding
3.2.8Drainage system
3.2.9Electrical power and lighting
3.2.10Water supply
3.2.11Ventilation
3.2.12Lightning prevention
3.2.13Fire protection
3.2.14Access
3.2.15Mechanical handling equipment
3.3Facility operation-Description of the activities
3.3.1Operational radiation safety
3.3.2Facility operations, activities
3.4Waste inventory
3.4.1Conditioned radioactive waste
3.4.2Unconditioned radioactive waste – DSRS
3.4.3Unconditioned radioactive waste –Radioactive lightning rods (RLR’s)
3.4.4Unconditioned radioactive waste – Low activity sources
3.4.5Unconditioned radioactive waste – Solid radioactive waste
3.4.6Drum/package storage arrangements
3.4.7Retention time of the stored waste
3.4.8Expected waste generation
3.5The radiation monitoring
3.5.1Description of the personnel dose monitoring programme
3.5.2Description of the ambient dose monitoring programme
3.6Security
3.7Decommissioning plan
4.Safety assessment
4.1Context of the safety assessment
4.1.1Purpose and scope of the safety assessment
4.1.2Safety assessment methodology/approach
4.1.3Regulatory framework
4.1.4Assessment endpoints
4.2Development, justification and assessment of scenarios
4.2.1Normal operation
4.2.1.1Normal operations activities
4.2.1.2Assessment cases
4.2.2Accidents internal
4.2.2.1Scenarios
4.2.2.2Assessment cases
4.2.3External accidents human induced
4.2.3.1Scenarios
4.2.3.2Assessment cases
4.2.4External natural accidents
4.2.4.1Scenarios
4.2.4.2Assessment cases
5.Analysis/Discussion
5.1Site and Rakovica Facility engineering analysis
5.2Discussion of assessment results
5.2.1Normal operation
5.2.2Accident internal
5.2.3External accidents human induced
5.2.4External natural accidents
6.Management of uncertainties
7.Limits, control and conditions
8.Synthesis and conclusions
9.Annexes
9.1Annex 1 – Waste acceptance criteria
9.2Annex 2 – Input data and results for the general fire modelling with Hot Spot code
List of Figures
Figure 1 Maps of the Rakovica area, site layout
Figure 2 Seismic actitivities at the territory of B&H
Figure 3 Rakovica Facility layout
Figure 4 Design of the RLR Eu-152/154, Led shield with tungsten ingot
Figure 5 Drum/package arrangement in Waste Processing Building
Figure 6 Dose rate monitoring (µSv/h)
Figure 7 Ambient dose rate in vicinity of the RLR’s Eu-152/154
Figure 8 General plume model and release of the radioactive material Am-241 and U-238 in case of fire
Figure 9 Rectangular shaped drainage channel
List of Tables
Table 1 Summarized climate characteristics
Table 2 Dose rates of selected radionuclides with and without concrete barrier
Table 3 Dose rates at selected distances from the Eu-152/154, activity 3.6 GBq
Table 4 Conditioned radioactive waste stored in Storage Building
Table 5 DSRS stored in Rakovica Facility
Table 6 DSRS stored in Rakovica Facility
Table 7 RLR’s stored in Rakovica Facility
Table 8 RLR’s stored in Rakovica Facility
Table 9 Low activity sources stored in Rakovica Facility
Table 10 Solid radioactive waste stored in Rakovica Facility
Table 11 Retention time for a selection of DSRS stored in the Rakovica Facility
Table 12 Estimated activities of the RLR’s installed on the territory of B&H
Table 13 Overview of the stored DSRS in interim storages at the territory of B&H
Table 14 Summary of the personnel dose monitoring
Table 15 Dose rate monitoring results (Nov 10, 2014)
Table 16 Overview of considered normal operation activities
Table 17 Contribution to annual doses to workers and police security during normal operations
Table 18 Overview of the PIE types considered for internal accidents
Table 19 Overview of the relevant scenarios with estimated probability and impact
Table 20 potential dose to the worker exposed to Co-60, 3.7 GBq
Table 21 Dose to the worker due to intake of selected radionuclides
Table 22 Dose to worker in case of accident short term exposure
Table 23 Dose rate from stored category 2 source, Co-60 in case of shielding loss
Table 24 Overview of the PIE types considered for external accidents human induced
Table 25 Overview of the relevant scenarios with estimated probability and impact
Table 26 Overview of the PIE types considered for external natural accidents
Table 27 Overview of the relevant scenarios with estimated probability and impact
Table 28 Results for the drainage channel flow rate
1.The context of the Safety Case
1.1The generic Safety Case context
Radioactive materials, mainly sealed radioactive sources (SRS), have been used in Bosnia and Herzegovina (B&H) for a number of various medical, industrial, research and teaching activities during the past fifty years.
B&H authorities, in 1998, established Rakovica Radioactive Waste Storage Facility (Rakovica Facility) in order to accommodate for a relatively long term period the disused sealed radioactive sources (DSRS) for which regulatory control was lost as a result of the war (1991-1995). Since then, the Rakovica Facility has been operated as the centralized radioactive waste storage facility of the Federation of B&H[1]. The operator of the Rakovica Facility has been the Institute for Public Health of FB&H (Institute).The purpose of the Rakovica Facility is to provide for safe and secure storage of DSRS, mainly radioactive lighting rods (Eu-152/154), but also various industrial gauges and sources used in medicine. In addition, low level solid radioactive waste collected as a result of the incidents is stored.
1.2B&H radiation protection framework
The Radiation Protection and Nuclear Security Act (Act), promulgated in 2007, defines the legislative framework on radiation safety and security issues in B&H[2]. The State Regulatory Agency on Radiation Protection and Nuclear Safety (Agency) was established in accordance with the Act provisions. The Agency is empowered on legislation, authorization and inspection in radiation safety and security. In terms of the Act, the Agency is the responsible authority for licensing and exercising regulatory control over the Institute.
In accordance with the Act provisions, Regulation of the radioactive waste management will be promulgated by the Agency. A Regulation on safe management of the radioactive waste and DSRS, based on international safety standards, has been drafted. As such, the draft version and international standards are used in this safety case as a basis for demonstrating safety.
The Agency and the Institute are different legal entities in line with principle of independence of the regulating authority and the operator of the radioactive waste storage facility.
The Institute is established by the Health Care Act of Federation of B&H (1997). Decision of the Ministry of Health of Federation of B&H (2001) and Licence (2011) by the Agency define scope of the work of the Institute in radiation protection. The Institute performs individual radiation monitoring, environmental radioactivity monitoring, workplace monitoring, medical examination of workers and storage of radioactive waste/DSRS.
1.3B&H radioactive waste management policy and strategy
The Agency developed the Policy for safety of the sources (Policy)[3]. The Policy included radioactive waste management emphasizes protection of humans, workers and population, now and in future from radioactive waste management activities.
The following radiation protection principles are described in Policy: Primary responsibility, The role of the institutions, Management system, Justification of the practice, Optimization of protection, Risk management, Protection of population now and in future, Prevention of accidents, Emergency preparedness, Protection actions, Graded approach, Threat assessment, Multilayer protection measures, Data confidentiality.
The Policy defines that the Agency will establish regulatory framework for radioactive waste management and will authorize technical services for management of the radioactive waste. The scope of the waste management license will cover one or more waste management operations, as appropriate. The primary responsibility for the waste management rests with the generator of the waste. The preferred option of disused sealed sources management will be return to supplier.
The Agency developed the national radioactive waste management strategy and defined a centralized radioactive waste management in B&H (2013)[4]. Generated radioactive waste, mainly DSRS that cannot be returned to their suppliers/manufacturers will be stored in the centralized storage facility. The operator of the centralized radioactive waste storage facility will be the Institute, as there being no other competent organization to assume this responsibility. The Agency is currently exploring options for a new site with robust buildings that could be used for centralized long term storage of radioactive waste/DSRS.Awaiting for the construction of the new centralized radioactive waste storage facility, the Rakovica Facility needs safety assessment in order to continue operation.
1.4The purpose and scope of the Safety Case
The purpose of this version of the Safety Case is toassess safety of the existing Rakovica Facility. A principal application of the Safety Case will be in the license application and approval process.It will be submitted by the Institute to the Agency as part of the application to get authorization from the Agency to continue operation of the RakovicaFacility.Inaddition,the Safety Case will be used:
- for optimization of the dose received by the workers of the Institute,
- as a basis for identifying measures to upgrade the facility for conditioning of the DSRS,
- as a case study for the safety cases of the interim storages throughout Bosnia and Herzegovina, and possibly for the future centralized radioactive waste storage facility.
The Safety Case documents the assessments of the current status and operation of the Rakovica Facility based on SADRWMS methodology[5].RakovicaFacility was evaluated for compliance with national radiation protection regulatory requirements.Environmental impact assessment is not within scope of this Safety Case.
The Safety Case will be updated as prescribed every five years. In case of significant operational changes eg conditioning of the DSRS or receipt of the DSRS from interim stores throughout the country, the Safety Case will be updated following upgrade of the Facility.
Safety case will be updated as required, minimally in five years.
2.Strategy for safety
The strategy for demonstrating safety of the management of the DSRS atRakovica Facility is based on isolation and containment and includesboth passive and active elements.
Approach to waste managementwith regards to the following is regarded as contributing to safety:
- Management system,
- Compliant with B&H radiation protection legislation and relevant international standards and guidelines
- Clearly defined responsibilities for waste management
- Work procedures designed to reduce duration, frequency, and severity of exposure to hazards
- Trained, qualified and competent persons undertake work that is safety related
- Appropriate records on waste inventory and dose records kept up to date
- Multiple safety functions
- Radiation zones designated
- Radiation monitoring during waste management activities
- Defence in depth,
- Fenced area secured by the police
- Robust structure of the buildings with high integrity locks
- System for intrusion detection
- Shielding and confinement,
- Storage of DSRS takes place inside proper containment such as the original working shields or another type of suitable containment
- Dismantling of RLR’s inside shielded hotbox
- The optimization of shielding usage during all waste management activities including transportation and storage
- Selection of appropriate approaches to waste processing,
- DSRS received in original working shields or another type of suitable containment
- DSRS segregated for conditioning based on half-lives
- Compatibility of the processed waste with the WAC of disposal facilities,
- Minimization of the generated waste,
- Secondary radioactive waste is only expected when a leaking source is found or during accident scenarios when a source is damaged. The generation of secondary waste during such an incident will be minimized by isolating the source in a secondary containment to prevent further contamination.
3.Description of the Rakovica Facility, Facility operation and waste
3.1Description of the site
Rakovica Facility is located in the municipality of Hadzici, approximately 20 km west from capital Sarajevo on the regional road M5 between Sarajevo and Kiseljak (Fig 1). The site itself is government owned property with several store buildings within fenced area. The locality is semi urban with residential and agricultural areas. The closest public houses of the Rakovica settlement are approximately 100 m distant, both north and south of the Facility. There has been extensive construction of family houses and it is reasonably to predict that it will continue.
Figure 1Maps of the Rakovica area, site layout
The site is hilly and the Rakovica Facility is adjoined to a clay hill from which water comes in during rain.The site is surrounded with bushes and shrubs.
There are no surface water bodies in the immediate vicinity of the Facility. The closest surface water body, Rakovicabrook is 700 m distant. Geology of the area consists of Upper Cretaceous Flysch (water impermeable to slightly permeable rock) overlying Middle Triasiclimestones and dolomites (water permeable rock)[6].
The territory of BH is seismically relatively active. The recorded data on earthquakes in the area for the period 1879 to 2009 range from 3.6 to 5.1 Richter scale[7]. According to the map of expected maximum earthquakes (Fig 2), the Sarajevo area is located in area where there is a risk of earthquakes measuring 5.1 Richter scale.Earthquakes of such magnitude cause damage to buildings and structures.
Figure 2 Seismic actitivities at the territory of B&H
B&H, due to its geography and relief characteristics, has a complex climate[8]. Rakovica is located in the central Bosnia where continental climate prevails. Summarized climate characteristics are presented in Table 1.
Table 1 Summarized climate characteristics
Period / Average temperature (ºC) / Minumum temperature (ºC) / Maximum temperature (ºC) / Average annual precipitation (L/m2) / Minimum monthly precipitation (L/m2) / Maximum monthly precipitation (L/m2) / Maximum daily precipitation (L/m2)1961-1990 / 9.6 / -21.8 / 37.4 / 932 / 1 / 259 / 93.2
2005-2014 / 10.7 / -19.0 / 38.8 / 983 / 5 / 186 / 73.3
Basic climate characteristics are severe winters and hot summers. The absolute temperatures range from approximately -20ºC to nearly 40ºC. The average annual precipitation is nearly1000 L/m2, evenly distributed throughout the year. The highest recorded daily precipitation amounts for 93.2 L/m2. Snowfall contributes significantly to total fallout amount from November to April period.
3.2Description of the facility
3.2.1General facility description
The Rakovica Facility consists of two buildings: Storage Building and Waste Processing Building. The Storage Building is a reinforced concrete building previously used by the Police force for storage of explosive materials. The Waste Processing Building additionally constructed building designed for receipt, processing of DSRS/waste and interim store, before transferred to Storage Building. Even though the Waste Processing Building has never been finished and completed, it entered operation due to lack of operation capacities in the Storage Building and rather simple operations of receipt and emplacement of DSRS in working containers and dismantling of only radioactive lighting rods and smoke detectors.
3.2.2Buildings layout
The Rakovica Facility consists of two buildings, the Storage Building and the Waste Processing Building (Fig3)
The Storage Building is a simple one room building sized 6x5 m. The available storage area is ~25 m2floor space for heavy loads and three wooden shelves with total available storage space of ~10 m2 for DSRS in smaller working containers. There is a fence around the Storage Building with lockable door.
The Waste Processing Building layout provides several areas grouped in a radiation protection control area and a working area. The radiation protection control area consists of four rooms for staff preparation activities, while the working area layout is divided into reception/working area (~7 m2/~29 m2) and interim store (~9.5 m2). The reception/working area contains a vault of approximately 1m3 for drainage of liquids in case of possible decontamination. The reception/working area is provided with a workstation which consists of work bench, tool storage and space for storage of empty containers and the transport trolley. A fume hood is installed in the workstation. The interim store area is designated for the storage of RLR’s and DSRS in working containers such as industrial gauges etc., awaiting for conditioning and transfer to the Storage Building. Interior walls of the Waste Processing Building separate the various areas and provide radiation shielding. Access to the interim store is secured by lockable door.
Figure 3Rakovica Facility layout
3.2.3Building structure
The Storage Building has a solid anti-seismic design and robust construction. It is one story building 6x5 m made of reinforced concrete, including floor andceiling, additionally the roof is covered with ceramic tiles. It has two openings in the walls for providing natural ventilation, one glass window for natural illumination, a lockable door and a wooden rack with three shelves.
The Waste processing building is one story building, 8x10.5 m. It is completely built of fly ash bricks, both outer and inner walls. The ceiling has not been constructed. The roof is of ceramic tiles on wooden construction. The building has 6 windows, a double sided lockable metallic door and wooden lockable door for personnel. A 10 cm thick bench (4x1x0.8 m), made of cement, constitutes the base of the workstation.
3.2.4Building base slab/floor
The floors of the Storage Building and Waste Processing Building are reinforced concrete rafts, which also constitute the working floors of the storage facility. Resistance to the water penetration from the ground is not provided to the underside of the slab. It is not expected that water from the ground will penetrate the buildings. The Waste Processing Building is provided with an internal pit with capacity of at least 1m3. Liquid waste is not and will not be stored in the Storage Building, which is not provided with an internal drainage system.
Data on the load factor for the floor slab of the Rakovica Waste Processing Facility is not available. Heavy loads of up to 1 ton have been maneuvered in the building.
3.2.5The doors
The Storage Building and the Waste Processing Building have a 2 m and 1 m wide access doors, respectively. Door openings are of enough size for loaded hand trolleys to pass by. A separate personnel door is provided at the Waste Processing Building to separate personnel from waste movements.
3.2.6Finishes
The floor finishes and finish paintings of the workstation have not been done in either of the buildings.
3.2.7Shielding
The Storage Building concrete structure (45 cm thickness) provides radiation shielding to limit exposures outside the building. The door on the Storage Building is less efficient and radiation shine is observable through the door. Individual packages are shielded by other packages.