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Assessment of impacts on the aquatic environment from nuclear power projects. Platts European Nuclear Conference

Mark Liddiard, HR Wallingford

© HR Wallingford 2013

Our vision

To be the most respected international research and consultancy organisation in civil engineering and environmental hydraulics NCE Specialist Consultant of the Year (2013)

Water Floods Coasts Maritime Energy

Research


HR Wallingford - Overview

Independent consultancy specialising in civil engineering and environmental hydraulics since 1947. No direct funding from UK Government since 1982 and fully independent from any other commercial entity – reactor technology neutral. • Current turnover is ~$40,000,000 (USD) • Current Staff is ~300 (250 technical staff) • Largest commercial physical modelling laboratory in Europe at 1600

square metres. • Over 50 nuclear power projects in the UK and overseas. • Strong track record in UK nuclear new build programme. • Developing services & track record for international projects.


Our overseas offices

Houston New York

Wallingford

Abu Dhabi

Mumbai Kuala Lumpur

Shanghai

Perth

Brisbane Darwin

Hong Kong Martinique

Italy

Overseas staff


NPP impacts on aquatic environment

Usually assessed in the EIA and environmental permitting process: • Impact of thermal plume on

receiving environment • Impact of structures on wave &

tidal flow regime • Impact of structures on natural

sediment transport processes • Entrainment of marine life into

the cooling water system • Transfer of flood risk to other

receptors from construction of hardened defences


Aquatic environment impacts on NPP

Assessment studies undertaken as part of the safety case of the NPP: • Availability of water for cooling purposes and potential

requirement for an ultimate heat sink • Wave & current loading on structures for CWS, MOLF and sea

defences • Sediment ingress into CWS intakes • Flood risk assessment – coastal, fluvial and pluvial • Extreme event analysis – tsunami, cyclone / typhoons • Long term impacts of climate change – sea level / temperature

rise


Assessment studies likely to be required

Numerical & physical modelling of cooling water systems – impacts of waves & tidal currents on intakes & outfalls

Navigation simulation of marine offloading facilities for abnormal indivisible loads

Marine environmental impact studies – fish entrainment and sensitive receptors

Plant sea defence design and testing via physical modelling Flood risk assessment for coastal and inland sites Climate change adaptation and response to sea level rise Post-Fukushima flood hazard re-evaluation of existing NPP

for life extension


Current nuclear power studies

We have supported nuclear new build for PWR projects in the UK and MENA region Hinkley Point C: Design of cooling water systems through hydrodynamic modelling and physical

modelling tests Support to the design of the construction jetty, Navigation simulations for the MOLF at Combwich Wharf & temporary jetty, Site protection from coastal flooding for EDF (sea wall modelling).

Barakah, Abu Dhabi: Design of open channel cooling water intake and discharge systems for KEPCO

E&C Cooling water systems breakwaters are also primary sea defence. Tsunami risk examined as credible faults in Arabian Gulf. Possible impact of cyclones (but very rare cyclone track to site)


Customer Requirements for plant life extension

Following the Tohoku earthquake and tsunami (Japan) in 2011, NPP owners have started to undertake “beyond design basis” reviews as the basis for the external flooding safety case.

Existing UK NPP may continue to operate longer than the original life expectancy due to delays in new power stations being built in the UK.

Requirement to review and update safety cases for external hazards from flooding

As UK NPP are all built on coastal sites a significant programme of work is required.


Assessment of Nuclear Power Plant sites

For a nuclear power plant located on the coast the following factors need to be considered when considering water risk on site: Areas where the tidal level exceeds

the site level Previous occurrence of wave

overtopping of defence structure Previous occurrence of flooding at

the site

The main coastal flood risk on site is directly linked to the rate of overtopping.


Taking account of climate change and SLR

NPP must be safe from “beyond design basis” events following the Fukushima event in 2011, but also:

New nuclear power stations are being designed for: ~ 5 years to build Up to 60 years operational life Up to 100 years decommissioning

period

= very long design basis Adaptation to climate change and sea

level rise challenges is key safety driver

Adoption of UK EA H++ guidance is highly conservative (safe).


Assessing long design life and return periods

Service conditions: 1:1 to 1:10 year returns Design conditions: 1:50-1:500 year return

Overload conditions: 1:1000 to 1:10,000 year returns.


Case study of UK existing nuclear power station

Case study - power station is situated on the coast and protected by a shingle beach

HR Wallingford reviewed two previous flooding assessments

The potential mobility of the shingle bank may make analysis at the site uncertain

We considered issues associated with swell waves and potential beach movement

Ensuring the safety case for external flooding hazards can be met:


Current flood defence at site

Using a shingle beach as the primary flood defence is relatively rare for major industrial installations / structures

There is no single method for predicting the overtopping of a shingle beach which takes account of re-shaping

The prediction methods available make substantial simplifications, i.e. each only cover a part-response

Previous assessments had not included calculations of shingle beach reshaping

Beach re-shaping could be significant in determining the volumes of wave overtopping likely to occur during a storm event.


Outline of the review of waves and sea levels

Parameters considered for Nearshore sea

conditions

Extreme sea levels

Sea steepness

Offshore wave

conditions

Nearshore wave

conditions

Joint probability

Climate change

allowances


Specialist assessment of shingle bank adjacent to a UK NPP


Physical model of wave overtopping

Following review of extant flood risk safety cases and site visits by expert staff additional studies under way.

Physical modelling of the sea defence structure was recommended to reduce uncertainty.

This has been carried out by HR Wallingford and tests are now completed.

Subject to high degree of regulatory scrutiny (ONR).


Beach profile analysis

Testing sequence showing waves being run at scale model of shingle beach in large 2D wave flume. Measure and assess overtopping and shingle bank stability under variety of conditions.


Services for River Flooding & Climate Change

• Flood Spreading • Risk based system modelling • Develop flood risk software • Integrated flood risk management and asset management • Real time flood forecasting

River Flooding

• Assessment of climate change impacts • Define & analyse priority risks & opportunities from climate change • Climate Resilient Infrastructure Development Facility (CRIDF):

Hotspot mapping

Climate change

• Water resource planning • Hydrological modelling • Abstraction modelling • Optimising water management • Water quality modelling

Water levels


The Danube River Basin

The Danube River basin: Main river is 2 857 km long and drains 817 000 sq. km

Countries include: Hungary,Romania, Austria, Slovenia, Croatia, Slovakia, Bulgaria,

Germany, the Czech Republic, Moldova and Ukraine. Territories of FR Yugoslavia, Bosnia and Herzegovina and small parts

of Italy, Switzerland, Albania and Poland are also included in the basin.

Environmental legislation includes: Danube River Basin Management Plan EU Water Framework Directive


Map of NPP in Danube basin


Constraints to cooling water supply

Environmental Constraints

Thermal impact on

rivers users

Thermal impact on

river ecology

Flooding impacts on

Nuclear Power Plants

Plant shut down in extreme events

Long term impacts

over nuclear plant life


Thermal impact on river ecology

Water abstraction at cooling water intakes and its discharge could results in death due to:

impingement (trapping of larger fish on screens) entrainment (drawing of smaller fish, eggs and larvae through cooling

systems)

Extent of thermal occlusion in the river could result in: Varied width and depth of river occupied by water at temperatures that affect

the behaviour of migrating fish Estuarine system will vary through the tidal cycle – plumes will stream along

the bank during ebb tides and spread across the width of the river as the tide turns

Climate change impacts on the river temperature together with thermal dispersion could lead to an increase in algal blooms and potential eutrophication.


Plant shut down in extreme events

Regulatory constraints on reduced river flows or temperature increase in receiving waters could result in limited generation output. Absolute temperature of the water might approach or exceed max allowable for either environmental reasons or ‘ultimate heat sink’ of nuclear plant

During the heatwave of 2003 and 2006 EDF was forced to stop some reactors for a period of time. Case Study – Bugey, France Max increase in summer water temperature 5.5ºC (7.5ºC in summer) Max discharge temperature 30ºC (34ºC in summer) Max downstream temperature 24ºC (26ºC allowed for up to 35 summer

days).


Long term impacts

Long term impacts over the nuclear power plant life include: Trans-national issues between neighbouring countries within the Danube

Basin complying to nuclear regulations and environmental legislation Cumulative warming in the downstream direction (ideally require sufficient

separation between NPP to allow heat to dissipate to atmosphere) Wide range of seasonality of water temperature due to climate change

(risk of ice during the winter months) Risk of increased pollution in water intake due to other users Navigation issues due to restricted areas for safe passage Availability of water in sufficient quantities (other competing uses for

irrigation, drinking, industrial, etc. Net loss of water (if used for cooling towers) Concentration of suspended and dissolved matter in discharge if used for

cooling towers


Summary

• All NPP projects under consideration in Europe will have significant impacts on the water environment

• Aquatic environment is often a shared resource with competing uses and increasing concerns on scarcity of this resource

• Specialist assessment is required to support the safety case, EIA & environmental permitting processes

• Imperative to use consistent data, models and interpretation throughout the project life cycle

For further information please contact: [email protected]

+44 1491 822433

mailto:[email protected]

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