16.1.3 Regulation

Decommissioning represents a current challenge to the UK nuclear indus­try because many of the UK’s reactors have reached the end of their useful life.

Nuclear site licence holders are required to prepare strategies for decom­missioning of nuclear infrastructure. The Nuclear Reactors (Environmental Impact Assessment for Decommissioning) Regulations 1999 (EIADR99) as amended by the Nuclear Reactors (Environmental Impact Assessment

for Decommissioning) (Amendment) Regulations 2006 (EIADR06) require that nuclear reactor decommissioning is accompanied by an Environmental Impact Assessment (EIA) in addition to other requirements. The purpose of EIADR is to require assessment of the potential environmental impacts of projects to decommission nuclear power stations and nuclear reactors. In addition, the intention is to make the decision-making process open and transparent. EIADR require that the public and other relevant stakehold­ers be consulted from an early stage, regarding the environmental impacts of the options being considered for a proposed decommissioning project.

An Environmental Statement containing details of potential environ­mental impacts must be submitted to the Health and Safety Executive before any decommissioning work can be carried out, and once they have consulted with various bodies, i. e. the environment agencies, conservation bodies, local authorities and stakeholders, permission may be granted.

HSE have developed policy (HSE, 2005) and guidance (HSE, 2008) on the criteria to be satisfied for sites to be de-licensed. The basis is the dem­onstration of ‘no danger’ remaining from the presence of any remaining contamination on the site. The requirement is ‘to show that any such remain­ing radiological hazard will not pose a significant residual risk to any person, for all reasonably foreseeable uses to which the site may be put and not just for its next future use. Based on the reasoning laid out in the HSE publication “Reducing Risk and Protecting People”, HSE believes that the annual risk of a fatality of one in a million to an individual is regarded by society as “broadly acceptable”.’

HSE (2008) also refers to the need to show that risks are ALARP (as low as reasonably practicable). HSE’s preferred method for demonstrating that the risk criterion has been met is the application of derived concentra­tion levels for the clearance and exemption of radioactive substances (IAEA, 2004). These values are calculated on the basis of a dose criterion of 10 qSv/y and a set of exposure scenarios.

The management of radioactively contaminated land on a nuclear licensed site is carried out by ONR. ONR regards radioactively contami­nated land and emplaced radioactive substances on nuclear licensed sites as accumulations of nuclear matter, unless they are, or arise from, author­ised disposals, and it requires licensees to manage it as such. The licence conditions require that licensees control or contain nuclear matter, to record the amount of radioactive material and its location, and justify and demonstrate the arrangements to maintain safety by means of a safety case.

For radioactively contaminated land that is not on a nuclear licensed site, a different set of regulations apply. Part IIA of the Environmental Protec­tion Act 1990 provides a regulatory regime for the identification and reme­diation of contaminated land that is causing unacceptable risks to human health or the wider environment. In 2006 and 2007 this was extended to cover radioactivity and to cover land contaminated with radioactivity origi­nating from nuclear installations (different regulations were enacted in England and Wales and in Scotland). The objectives for the extension of Part IIA to radioactive contamination remain the same: to provide a system for the identification and remediation of land where contamination is causing lasting exposure to radiation for human beings and where ‘interven­tion’ is liable to be ‘justified’. A key aspect is that the land should be ‘suit­able for use’. The criteria for designating land as ‘radioactively contaminated land’ are based on a probability weighted annual dose of 3 mSv from the contamination. In the case of contamination in the form of discrete radioac­tive particles that could give rise to doses above 50 mSv if encountered, decisions on whether the land should be designated as radioactively con­taminated land are based on a number of factors.

In the context of new development of land, radioactive contamination may also be deemed a material planning consideration under the relevant Town and Country Planning Act.

17.1.3 Naval reactor test establishment (NRTE) Vulcan

Vulcan is situated in Caithness adjacent to the Dounreay site. The site is owned by the MoD on a long lease from the NDA and operated by Rolls Royce. Its purpose is to test nuclear submarine propulsion reactors on shore in support of the operating fleet.

Construction of the Dounreay Submarine Prototype 1 (DSMP1) was started in 1957 and the first reactor was operational in 1965. The facility tested a number of reactor cores until it was shut down in 1984. The facility includes a pond where fuel from the testing programme is stored.

A second facility, the shore test facility (STF) was commissioned in 1987 for a similar testing programme on the next generation of submarine reac­tors. It is planned to operate this facility until 2015 when it will no longer be required (UK Government, 2011) as a reactor core prototype plant. Associated with the STF is a pond where fuel from this testing programme is stored and a decontamination and waste treatment facility (DWTF) in which is stored activated organic resins from decontamination operations in the STF. Operational LLW from Vulcan is transferred to Dounreay for disposal and LLLE is transferred to the Dounreay LLLETP.

Post-operational activities and early decommissioning could start in 2015 and be completed by 2021. Options to continue support to the naval nuclear propulsion programme from the Vulcan site are being considered together with a decommissioning programme. Final decommissioning and demoli­tion could take up until 2050 to be completed. Some of this could be planned in and associated with the decommissioning programme at Doun — reay. The decommissioning waste volumes are small compared to Dounreay and could be incorporated into Dounreay’s management arrangements. The lifetime packaged volume of LLW to be disposed of at Dounreay is esti­mated to be around 3,600 m3. The lifetime packaged volume of ILW, possibly to be stored at Dounreay, is estimated to be around 156 m3 (NDA, 2011a). However, the Scottish HAW policy does not apply to Vulcan so the final end-point for this ILW may be different from that of Dounreay’s.

18.1.6 Nuclear research and test facilities

SNF from both domestic and foreign research reactors, in addition to limited quantities of commercial SNF, is stored at facilities at the SRS and the INL prior to further disposition. The DOE continues to receive SNF from foreign and domestic research reactors, but plans to complete the program for receipt of foreign research reactor SNF in 2019. No date has been set for completing receipt of SNF from domestic research reactors. The DOE also stores SNF from former defense production reactors. Its current policy and planning includes managing foreign research reactor SNF for 40 years or until ultimate disposition.

There are 20 tailings management sites that have resulted from the opera­tion of uranium mines in Canada: 14 in Ontario, four in Saskatchewan and two in the Northwest Territories. Decommissioning of uranium mines and mills is governed by the Uranium Mine and Mills Regulations under the NSCA. The Cluff Lake Project is described here as an example of the type of activities that are undertaken for safe decommissioning.

Cluff Lake project

The Cluff Lake Project, which is owned and operated by AREVA, was completed at the end of 2002, when ore reserves were depleted. More than 28 million tonnes of U3O8 was produced over the 22-year life of the project.

Site facilities included the mill and tailings management area (TMA), four open-pit and two underground mines, the camp for workers and site infra­structure. Cluff Lake was the first of the northern Saskatchewan uranium mines to be decommissioned. The decommissioning licence was received from the CNSC in July 2004. The objective is to return the site as closely as practical to its original state in a manner that both protects the environ­ment and allows traditional uses such as fishing, trapping and hunting to be carried out safely.

Decommissioning the mill involved two phases, which were completed in 2004 and 2005. The mill demolition work was broadly similar to demolition of other comparable size industrial facilities, with special measures needed to protect workers from residual contamination and industrial hazards, and to prevent the spread of contaminants into the environment. Waste materi­als were disposed of in one of the open pits at the site, together with much larger volumes of waste rock.

Decommissioning of the TMA was initiated by covering the tailings with till[32] in stages to promote consolidation. The local till material developed from an adjacent borrow area was used for covering the tailings materials. When consolidation was complete, the TMA cover was contoured to provide positive drainage, using locally available till with a minimum cover thickness of 1 m, and then re-vegetated. Extensive characterization of the tailings and the site ’s geology and hydrogeology has been performed to acquire reliable data on which to base the assessment of long-term perform­ance. One of the objectives of the follow-up monitoring program is to verify the key assumptions used in the long-term performance assessment.

Two open pits have been used for the disposal of waste rock, with one of these two pits also used to accept industrial waste during operations and decommissioning. This waste included the mill demolition waste.

The standards prescribe the general pre-disposal waste management con­siderations, guidelines and standards for Necsa and also provide a frame­work for the development of specific pre-disposal waste management standards for inclusion in the ‘facility specific solid radioactive waste man­agement programmes’.

20.1.8 Quality requirements for solid radioactive waste management

The arrangements for compliance assurance during all waste management process steps ensure proper implementation of the waste management system. This quality management programme will provide the guidelines for ensuring that

• Facility-specific waste management programmes are developed in accordance with the Necsa waste management plan and system requirements

• The facility-specific waste management programmes are properly implemented

• Proper quality control is executed during all waste management proc­esses (waste generators and waste operators).

Sealed spent radioactive sources are currently held in the provincial nuclear waste storage facilities, in the centralized sealed source storage facility, or at the user’s premises. These radioactive sources have not been conditioned into a stable form, so they occupy large volumes of storage space and pose high potential risk. China is making an effort to establish an R&D base to develop radioactive source conditioning technology as soon as possible for the purpose of improving the safety of radioactive source storage. At the same time, China is exploring options for disposal of spent radioactive sources; it is expected to seek a long-term solution for spent radioactive sources. To meet the need for application of radioactive sources, since the 1960s China has invested in constructing a different scale of storage facili­ties in Beijing, Changchun, Lanzhou and Wuxi to accept and store RAW arising from nuclear technology applications, including disused sealed sources.

Seawater was pumped into the reactor cores and the SF storage pools for about two weeks, in an effort to cool the fuels. The total amount of seawater injected before March 25, when it was replaced by the injection of newly delivered pure water, was 2842, 9197, and 4495 kL for units 1, 2 and 3, respectively. It was estimated that as much as 32 tonnes of sea salt may have accumulated in the reactor units. Boric acid was added to the cores to func­tion as a neutron absorber to prevent re-criticality by the collapsed fuels [ 5] . Circulation of the water using the circulation lines was found to be impossible because there were appreciable leakages in reactor and/or con­tainment vessels, through which injected water continuously flowed out from the reactor building to the basement of the turbine building. The concentration of cesium-137 in the contaminated water exceeded the order of magnitude of 106Bq/cm3. By the middle of June 2011, a new water treat­ment system to decontaminate the highly contaminated water flowing from the cores had been established, and the circulation injection cooling using this facility was started in late June. This system (described in more detail in Section 24.5) cleanses the highly radioactive water, recovered from the basement of the building, and injects the decontaminated water back to the core. After removing radionuclides, water is desalinated before re-injection, reducing the salt content in the water to less than several ppm as of July 2012. The addition of seawater to the core, though it was unavoidable during the emergency, raised an issue of the adverse effects of the salt, in degrading of the vessels and other devices, as well as reacting with the fused fuels to form complicated chemical forms of debris.

A total of 747 underground detonations were conducted in Yucca Flat (USDOE, 2000b), an extensional basin located north of Frenchman Flat in the eastern NNSS (Figs 26.3 and 26.5). Some 664 were in alluvium and volcanic rocks in the unsaturated zone; 76 were in saturated alluvium and volcanic rocks; four in carbonate rocks with two of the detonations in the unsaturated zone and two below the water table; three detonations were in granitic rock in a small Cretaceous stock at the north end of the Yucca Flat basin (Pohlman et al ;, 2007). The radiological source term for detonations in the unsaturated zone remains in the unsaturated zone with two excep­tions. Detonations near the water table may directly inject radionuclides

540 000 560 000 580 000 600 000

Yucca Flat/ Climax Mine CAU 97 (720 CASs)
N
Western _/ Pahute Mesa CAU 102 (18 CASs)
20 19
15
10
Rainier Mesa/ Shoshone Mountain CAU 99 18 (66 CASs)
1
30	11
Frenchman Flat CAU 98 (10 CASs)
27
23 22
Nevada National Security Site

26.2 Shaded relief map of the Nevada National Security Site showing the location of sites of underground testing of nuclear weapons. The 907 underground detonations are identified as corrective action sites, a subset of the number of underground detonations. Clusters of corrective action sites are grouped into corrective action units (CAUs) and the hydrology and geology of the four major CAUs are described in this chapter.

26.3

Generalized geologic map of the Frenchman Flat basin of the southeast Nevada National Security Site showing the domain area for numerical models of groundwater flow and radionuclide transport at sites of underground testing. Stiple = Quaternary playa deposits; white = Quaternary/Tertiary alluvium; light gray = Miocene volcanic rocks; cross-hatch = Quaternary/Pliocene basaltic rocks; dark gray = Precambrian and Paleozoic sedimentary rocks. Dashed line is the Frenchman Flat hydrostratigraphic framework model boundary. Solid line is the Nevada National Security Site boundary. Dots show the location of ten underground nuclear detonations in the Frenchman Flat corrective action unit.

26.4

Generalized geologic map of the Yucca Flat-Climax Mine (YF-CM) corrective action units showing the domain area for numerical models of groundwater flow and radionuclide transport at sites of underground testing. Stipple = Quaternary playa deposits; white = Quaternary/Tertiary alluvium; light gray = Miocene volcanic rocks; diagonal line = Mesozoic granitic rocks; dark gray =

Precambrian and Paleozoic sedimentary rocks. Dashed line is the YF-CM hydrostratigraphic framework model boundary. Solid line is the Nevada National Security Site boundary. Dots show the location of 747 underground detonations in the Yucca Flat-Climax Mine corrective action units.

into the water table. Underground detonations that created surface subsid­ence craters can accumulate surface runoff in the craters. Enhanced infiltra­tion in the crater bottoms moves downward in the collapse chimneys through the test cavity of underground detonations, and may transport radioactive contaminants to the saturated zone. Similarly, underground tests in the unsaturated and saturated zone of subsurface volcanic rocks may directly inject radionuclides into the underlying carbonate aquifer or radionuclides may move downward along local faults and fractures. Local flow of groundwater may transport radionuclides along faults driven by transient pressure gradients created by pressurization of low permeability zeolitized volcanic rocks during underground testing. The phenomenology of underground tests detonated in carbonate rocks is significantly different from tests conducted in other rocks types (Carle et al., 2008; SNJV, 2008). The thermal decomposition of carbonate rocks releases large quantities of CO2 gas that contributes to pressure and density-driven flow. Additionally, radionuclides released in saturated carbonate rocks may be transported directly in the regional groundwater flow system.

Groundwater flow along the length of the Yucca Flat basin is limited by restricted regional underflow from a combination of confining units bound­ing the basin on the north (granitic confining unit), on the northeast (lower clastic confining unit) and on the west (upper clastic confining unit) (Laczniak et al., 1996; Bechtel Nevada, 2006). Recharge in the basin interior is low from the arid climate and downward drainage to the LCA is addition­ally restricted by the presence of a thick and continuous tuff confining unit at the base of the volcanic section above the carbonate aquifer. Directions of groundwater flow in the alluvial and volcanic aquifers in the Yucca Flat basin are variable and these flow systems are incompletely coupled to the carbonate aquifer (Fenelon et al., 2010)

The BSK 3 container concept is intended for the direct borehole disposal of SNF in salt rock. The container can accommodate the fuel rods from three PWR or nine BWR fuel assemblies. The container is unshielded and has a maximum diameter of approximately 440 mm. The diameter of the BSK 3 container was selected so that the SNF could be disposed of in the same type of borehole that is planned for the disposal of HLW casks. A variation BSK 3 concept referred to as the ‘Triple-Pack’ was developed by DBE Technology GmbH to contain three HLW casks with a diameter of 430 mm. Using the Triple-Pack and BSK 3 concepts for borehole disposal would optimize the use of handling and emplacement equipment requirements.

ANDRA’s agents may be producers of waste in their own right: any site remediation results in the generation of waste. Therefore agents must, before the remediation work, measure and characterize the waste from remediation projects. There again, experience shows that taking these issues into account upstream minimizes delays in administrative treatment and hence the storage time on the polluted site for the waste packages awaiting decision. This delay can be tricky if the owner is a private individual.

Similarly, for certain categories of waste, the agent may need to discuss with those responsible for a disposal site (current or planned), defining upstream the best conditions for characterization, packaging and manage­ment of waste arising from remediation sites. In any case, ANDRA as a waste generator must be exemplary in terms of waste and therefore how to take care of it.