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Original text

Proposed edit

Comments

86-89

In case of severe natural disruptive events or human intrusion beyond the design basis, the application of the radiological protection system has to be considered with reference to emergency and/or existing exposure situations.

This statement is confusing and does not recognise the different timeframes that needs to be considered when thinking about the correct radiological protection criteria for different stages of the lifecycle of a disposal facility.

Inadvertent human intrusion into a near-surface disposal facility should always be taken into account at the design stage. Any reasonable potential inadvertent human intrusion scenario should be considered and the dose implications for future generations understood.

Setting out suitable dose criteria for the possibility of inadvertent human intrusion is a significant safeguard against the disposal of radioactive wastes that would pose an unacceptable risk in the future when control of a disposal facility can no longer be assumed to be maintained.

In addition, natural disruptive events that might reasonably be predicted to occur while the hazard remains in a near-surface disposal facility should be taken account of at the design stage regardless of the severity. You could argue that “low frequency” natural disruptive events that are unlikely to occur during the lifetime of a disposal facility (including a sufficient post-closure period) need only to be considered from a perspective of optimisation, but this in nothing to do with the severity of the event.

150-151

..at a later stage for transport to, and emplacement in, a disposal facility

at a later stage for further management.

The disposal of solid waste is one possible management option after storage. There is also the possibility that waste will have decayed sufficiently to allow recycling or other waste treatments.

We also believe this is more consistent with text at paragraph (5).

163

..assure the protection….

assure the necessary protection

Suggested minor edit

182-184

can be cleared from further radiological protection control measures. Storage may also be necessary if suitable disposal facilities are not available, however, it is an interim step…..

can be managed under radiological protection control measures commensurate with the reduced risk. Storage may also be necessary if suitable disposal facilities are not available: in this case, it is an interim step….

Suggested edit to allow for waste to be managed at a lower waste category, as well as cleared from radiological protection measures.

220-223

They apply to planned facilities and to the transitioning from one phase to the next, but can also be applied retrospectively, i.e. to currently operating or closed facilities under institutional control

No suggested edits

The retrospective application of the standards suggested here might benefit from the inclusion of some text to recognition that the current state of a facility may hinder close adherence to updated recommendations.

In the UK where a disposal facility has been previously released from the regulatory systems this could be treated as an existing exposure situation, assuming there was a release of activity. For a disposal facility that is closed but still be under regulation, the operator would need to consider the implications of the changes in standards, however, if compliance with the modern standards could not be clearly demonstrated this would not necessarily require waste to be retrieved.

272-273

This depth range is not indicative only and is not precise.

This depth range is indicative only and is neither precise nor prescriptive.

Suggested edit for clarification purposes

292-295

Conversely, long-lived radionuclides, those with a half-life greater than 30 years that are weak-beta or alpha emitters, can still be a hazard in the long term, but generally do not represent a significant hazard during the operational phase, as the waste is generally handled such that the potential for ingestion and inhalation are minimized.

Conversely, long-lived radionuclides, those with a half-life greater than 30 years that are weak-beta or alpha emitters, can still be a hazard in the long term, but generally do not represent a significant hazard during the operational phase, as the waste should be managed such that the potential for ingestion and inhalation are minimized.

Suggested edit to strengthen the point being made

309-310

It is internationally recognised that there is no implied intention to retrieve disposed waste even if technical options to do so were available.

It is internationally recognised that the act of authorised disposal of radioactive waste, by definition, implies no intention to retrieve disposed waste, even if technical options to do so were available. 

Suggested edit to strengthen the point being made

325-329

Access, whether deliberately or inadvertently, to waste in a closed near-surface facility is easier compared to waste disposed in a geological disposal facility. Consideration should be given to different approaches to reduce the possibility and consequences of post-closure inadvertent human intrusion through site selection, design, management, and institutional oversight and control.

The potential for intrusion into radioactive waste in a closed near-surface facility is easier compared to waste disposed in a geological disposal facility.  For the purpose of radiological protection when planning a near-surface disposal facility consideration should be given to approaches to reduce the possibility and consequences of post-closure inadvertent human intrusion through site selection, design, management, and institutional oversight and control

This is potentially confusing; the consequences of informed and deliberate intrusion should be excluded from consideration. Those doing so should bear the responsibility.

The suggested edits have been provided as a possible option to address this point by removing reference to deliberate intrusion.

333-334

This should address the possibility of no control being in place over the facility in the future.

Thus, there should be no reliance on control being in place over the facility, in the future.

Suggested edit for clarification purposes

344-345

The hazard of inadvertent human intrusion into waste that contains mainly…..

The potential consequences of inadvertent human intrusion into waste that contains mainly….

Inadvertent human intrusion is not the hazard. It is a possible scenario that needs to be taken account of.

The suggested edit is to address this point.

352-355

The likelihood of deterioration of the barriers caused by deliberate human actions can be reduced by avoiding, to the extent possible, locations with valuable underground mineral, water and other resources.

The likelihood of deterioration of the barriers caused by human actions can be reduced by avoiding, to the extent possible, locations with valuable underground mineral, water and other resources.

The use of the term "deliberate" is generally associated with knowledge of a disposal facility. I don’t think that the word “deliberate” is needed here and would suggest removing it to avoid confusion.

362-379

a. Landfill sites may be suitable for some very low-level waste. The duration of control of sites is generally short, and waste cannot be assumed to be isolated from the environment for more than a few tens of years.

b. Disposal by leaving waste in situ, e.g., foundations of decommissioned buildings.

c. Surface trench disposal on designated sites is used for large volumes of low-level waste.

d. Near- or on-surface engineered facilities such as vaults or boreholes to depths down to a few tens of metres are used for low-level waste.

e. Tailing dam facilities and open pit mines are used for uranium and NORM 372 mining tailings.

f. Underground caverns and mines are used for large volumes of low-level waste and provide possibilities for intermediate-level waste.

g. Disposal in stable geological formations a few hundred metres below the surface is the option currently adopted for high-level radioactive waste and is also suitable for intermediate-level waste. Recommendations for radiological protection considerations for deep geological disposal are provided in Publication 122 (ICRP, 2013).

a.             Landfill sites may be suitable for some very low-level waste. The duration of control of sites is generally short, and waste cannot be assumed to be isolated or contained for more than a few tens of years.

b.             Disposal by leaving waste in situ, e.g., foundations of decommissioned buildings.

c.              Surface trench disposal on designated sites may be used for large volumes of low-level waste. 

d.             Near- or on-surface engineered facilities such as vaults or boreholes to depths down to a few tens of metres may be used for low-level waste, and some intermediate-level waste.

e.             Tailing dam facilities and open pit mines may be used for uranium and NORM mining tailings.

f.               Underground caverns and mines may be used for large volumes of low-level waste and provide possibilities for intermediate-level waste.

g.             Disposal in stable geological formations a few hundred metres below the surface is the option widely adopted for high-level radioactive waste and is also suitable for intermediate-level waste.  Recommendations for radiological protection considerations for deep geological disposal are provided in Publication 122 (ICRP, 2013).

Some suggested edits to soften the statements made in this bulleted list.

381-382

A key concept in the disposal of radioactive waste is containment, which is the confinement of the radionuclides within the engineered barriers

Two key concepts in the disposal of radioactive waste are containment and isolation. Containment is the retention of the radionuclides within the engineered barrier

Suggested edit to give broadly equal weight to both concepts.

We suggest that "retention" might be a better substitute for "confinement", to minimise confusion with similar sounding term "containment".

387-388

Whereas, confinement relies on engineered barriers to ensure the necessary level of containment for a predefined period

Whereas containment relies on engineered barriers to ensure the necessary level of retention for a predefined period

The subject of the sentence should be “containment”. The proposed edits are to improve the clarity of the point being made.

699-703

The deliberate introduction of the near-surface disposal facility is a planned exposure situation, nevertheless exposures from the facility are not planned to occur as such. The aim is to prevent and reduce exposures to as low as reasonably achievable, taking economic and societal factors into account, both in the operational phase (waste emplacement and closure) and in the post-closure phase when the facility is functioning as a passive system.

The act of disposal of radioactive waste to a near-surface disposal facility involves the deliberate introduction of a source into the environment, and so is a planned exposure situation.  Nevertheless, exposures from the facility are not planned to occur: the aim is to prevent most exposures and reduce residual exposures to as low as reasonably achievable, taking economic and societal factors into account, both in the operational phase (waste emplacement and closure) and in the post-closure phase when the facility is functioning as a passive system.

Suggested edit for clarification

712-713

As such, the risk should be considered in terms of both the magnitude and likelihood of occurrence of these exposures.

As such, the risk in any given year should be assessed as the product of the magnitude of, likelihood of occurrence, and detriment due to, these exposures.

Suggested edit for clarification

747-764

Near-surface disposal facilities are at various phases of development and operation in several countries: under design, under construction, in operation or closed and under some degree of regulatory control. Disposal facilities in operation or already closed and under direct oversight are considered as situations where the source is under control; these are therefore planned exposure situations. If an operational or closed disposal facility evolves in line with its planned and designed functioning as defined in the safety case, the concept of planned exposure situation continues to apply. While the facility should be designed to protect future generations, these are invariably judged by today’s standards and changing societal expectations or priorities may impact how the facility is judged and managed. In addition, there could be a breakdown of controls. Within the context of the current system of radiological protection, which itself may have changed, the situation could be considered as an existing exposure situation, requiring decisions to be taken, although not necessarily urgently, to bring the facility under control again (e.g. re-establishment of a control regime or retrieval of the waste).

Transcending the particular exposure situations that are deemed to apply during the various stages of the lifecycle of a near-surface disposal facility, the system of protection is implemented by assessment of the situation, justification of taking action, and optimisation of the protection actions using appropriate dose criteria for the individuals impacted.

While the statements made in these paragraphs are correct and explain how the exposure situations evolve over time as the disposal facility moves through the different stages of its lifecycle the issues regarding the application of the exposure situations and associated criteria when a facility is planned and designed are not clearly expressed.

The objective from a regulatory perspective when permitting a new near-surface disposal facility is to ensure that it can operate safely but also that it will not pose a risk to future generations. We are therefore taking a look into the future and asking for assessments to demonstrate that the future performance of a disposal facility would be acceptable under the current standards of radiological protections when we can no longer reasonably claim that control of a facility is likely to be maintained.

Currently in the UK for near-surface disposal facilities we do not accept any claims that control can be exercised beyond 300 years and as such the consequences of inadvertent human intrusion beyond this timeframe needs to be limited. Currently we use doses that are analogous to those that our current society would accept from an existing exposure situation; where intervention would only be considered.

In making these judgements at the planning and design stage we are still considering “potential exposure situations” but using the criteria from the current “existing exposure situation” to help us make judgments regarding the suitability of the planned disposal facility for the proposed radioactive waste inventory.

We believe that the ICRP document would benefit from making this point much clearer in the current document. This would help distinguish between an existing exposure situation that might arise as a result of an accident during the operational phase of a disposal facility.

780-783

Potential exposures may occur as a result of an accident at the facility or natural disruptive event. The risk associated with such events is a function of the probability of the event causing a dose, the magnitude of the exposure and the probability of detriment due to that dose.

No suggested edits: I believe the text would be clearer if the relevant “timeframe” that is being discussed is made clear. (see comments for details).

The current text is potentially confusing as it does not make a clear separation regarding how exposure situations should be considered depending on what stage a near-surface disposal facility is in its lifecycle. I have set out below my thinking in relation to the different timeframes that need to be considered to help explain a bit more what I am getting at with this comment.

When considering the timeframe for planning, designing and constructing a disposal facility prior to any radioactive waste being disposed assessments are made to ensure that the disposal facility and the proposed radioactive waste inventory do not present an unacceptable risk both in the period where the site is controlled and afterwards. We therefore talk in terms of “planned exposure situations” which includes both “normal” and “potential” exposure situations. Potential exposures will address possible future events such as inadvertent human intrusion to inform the design and an acceptable inventory. The criteria used in these situations are generally to ensure that any potential exposures that might result, if these events were to happen, did not give rise to doses that would require some form of intervention if they were being considered as an existing exposure situation at the time the event might happen (the future timeframe).

When considering the timeframe when a disposal facility is being operated under regulation and an accident occurs this would be considered as an emergency situation and treated accordingly.

For the timeframe after a disposal facility is closed there is a period where it continues to be regulated and during which Inadvertent human intrusion should be prevented while unanticipated natural events (outside the design basis) might give rise to radionuclides migrating from the facility earlier than planned.  This type of natural event might be managed as an existing exposure situation and decisions to intervene or not will need to be taken by the regulatory body at that time.

For the timeframe where a facility is no longer subject to control and hence knowledge and resources to act may not be available. It is primarily for these situations that we plan and design for disposal facilities to perform such that any dose consequence that the future population would incur we would find acceptable in our current society. This is important because we have to assume that the future society is unable to protect itself as it would be unaware of the hazard.

Our only means of addressing these matters are therefore at the planning and design timeframe.

825-827

Table 1

While the criteria set out in this table provide a summary view of the application of the exposure situations the issues associated with the timeframes in the lifecycle of a disposal facility is not clearly addressed.

This is a particular issue for the “Protective approach” column where emergency exposure situations are introduced. While these would apply where an accident occurred in an operational facility they would not be a consideration in relation to the planning of a disposal facility as is implied by the “planning framework” column indicating that the “emergency exposure situation is part of the design basis.

In additional the table indicates that possible extreme future events play no part in the planning and design of a disposal facility (beyond the design basis). SEPA would argue that the investigation of the possible consequences of extreme events is an important tool in the design of a disposal facility as it allows us to understand more about the “defence in depth” or robustness of the disposal concept. While we would not compare any dose assessments with the numerical criteria for the relevant exposure situation investigating the radiological impact from such extreme events can help in the considerations of measure that might reduce the impacts if such events were to occur to help optimise the disposal facility design.

1023-1090

3.6. Protection of the environment

SEPA wholly endorses the need to assess the impacts of exposures from radioactive substances activities upon fauna and flora, and to demonstrate protection of the environment. However, we think that the framework referred to in Section 3.6 of the draft publication needs to be applied with some caution, especially to potential exposures of flora & fauna from a near-surface disposal facility that if such exposures do occur, they will be in the far future.

In section 3.5, that addresses Optimisation of protection, the system of radiological protection as applied to people recognises two types of planned exposure, normal and potential. Normal exposures are assessed against dose constraints and limits. Potential exposures are assessed probabilistically against risk constraints, unless probabilities cannot be reliably quantified, in which case, the existing exposure reference levels can be used to inform decision making at the planning and design stage.

However, the DCRLs as referred to in section 3.6 appear to have been established primarily to set bounds upon the impacts upon flora & fauna of environmental discharges during the operational phase of a facility. These DCRLs are therefore analogous to the dose constraints applicable to exposures of people in normal exposure situations. It is not at all clear to us how (or indeed if) these DCRLs should be applied at the planning and design stage for post-closure, post-institutional control, potential exposures of flora & fauna. We think this section would benefit from clearly setting out ICRP's thinking on this matter.

1399

Should a disturbing event occur and cause degradation of a disposal facility such that dose constraints (or the environmental DCRLs) are exceeded long-lasting exposure resulting from such natural disruptive events (with or without an emergency phase) should be referred to as ‘existing exposure situation’ and the recommended reference level for optimising protection strategies should be in the lower range of the band of 1 to 20 mSv year−1. Notwithstanding that past decisions may have been made about the reference level, it should be re-examined and established in agreement with the regulatory authorities and relevant stakeholders at the time of the event taking into account the prevailing circumstances. In addition, other activities associated with the facility may need to be re-examined in consultation with the stakeholders, such as environmental and health surveillance monitoring.

The discussion here is focused on the contemporaneous regulation of a disposal facility when a natural disruptive event occurs. Clarification of the different timeframes that should be considered would be helpful.

From a regulatory perspective it is more important to clearly state what the targets for the performance of a facility are in the future so that a permit can be issued at the planning and design stage.

Clarification on how the criteria for “existing exposure situations” may be used to inform the decisions at the planning stage in other words for planned exposure situations would be more useful in this section of the document.

A disposal facility should therefore be designed to be able to provide the required performance in the future if such an event should occur and hence not require interventions to protect the population.

1463-1475

Due to the challenges in establishing the probability of inadvertent human intrusion, the Commission considers it prudent to assume intrusion will occur, corresponding to an existing exposure situation. As such, reference levels in the lower half of the 1 mSv to 20 mSv per year band would be applied with the objective to progressively reduce exposure to levels towards the lower end of the band is recommended for off-site impacts. In addition, doses to environmental biota should be compared to the appropriate DCRLs. It should be noted that the optimum design of a disposal system may result in a distribution of doses from inadvertent human intrusion where some could be predicted to be above these reference levels. While establishing a single specific probability of inadvertent human intrusion is not possible, aspects of understanding the likelihood, such as, current human activities in the area or depth of the disposal facility, may be used to inform what generic or stylized intrusion scenarios are appropriate or can be used in the optimisation process, when evaluating alternative disposal system approaches.

It would be useful to make it clearer how the criteria for “exiting exposure situations” are being used at the planning stage to take account of the possibility of inadvertent human intrusion into a near surface disposal facility.

While we agree that, at the planning stage, it should be assumed that reasonable scenarios for inadvertent human intrusion will occur; we would argue that these should be characterized as “planned potential exposures”.

The use of the existing exposure situation criteria as a measure of the acceptability of a particular waste inventory to be disposed in the near-surface environment recognises the fact that if such an event were to occur this would be the level of exposures that our society today would generally find acceptable.

We would suggest that ICRP should clarify how the timeframes that is being considered changes how the different exposure situations are applied. In particular distinguishing between the planning and design timeframe where decisions regarding the permitting of a disposal facility need to be taken and the operational and post closure phases where the disposal facility is under regulatory control.

It is also important to recognise at the planning stage that indefinite regulatory control of a disposal facility cannot be assumed and this needs to be taken account of at the planning stage to protect that future population that do not have the ability to protect themselves.