Worked Example of NDA Prioritisation Calculations Summary

@U Dounreay Programme Management Support Unit Document Number: PMSU(06)P09 Title: Date 10th September 2006 Worked Example of NDA Prioritisation Calculations Status: Issue 1 Classification: None Issued By: Dounreay PMSU Page 1 of 23 Summary This paper gives a demonstration of the calculations required for the Nuclear Decommissioning Authority’s Prioritisation Process. Readers will need to be familiar with the prioritisation process as defined in NDA Prioritisation Procedure, EGPR02 and its supporting instructions EGPR02 WI01, Instruction for Calculation of Radiological Hazard Potential and EGPR02 WI02, Instruction for Calculation of Chemical Hazard Potential. The calculations are based on a hypothetical plant on the Dounreay site. Prepared by: Terry Page Approved by: Position: Doug Graham Dounreay Programme Strategy Manager NDA Prioritisation Procedure Worked Example, Introduction This example uses the methodology given in the NDA Prioritisation Procedure, EGPR02 and its supporting instructions EGPR02 WI01, Instruction for Calculation of Radiological Hazard Potential and EGPR02 WI02, Instruction for Calculation of Chemical Hazard Potential. Readers should refer to those documents for definitions, abbreviations and methods. This document does not explain the methodologies. The example demonstrates the calculation of the Safety and Environmental Detriment of a facility and the Project Benefit Measure of a project as required by steps 2, 3 and 4 in EGPR021. The subsequent use of the measures is not covered by this example and readers should refer to EGPR02 for further guidance. The example is written on the assumption that practitioners understand the UKAEA CWBS and can extract data from the UKAEA planning tools. The example works through the Safety and Environmental Detriment (SED) calculation for a redundant chemical plant and the Project Benefit Measure (PBM) for the combined Initial and Interim Decommissioning Project for this plant. The plant is based on a real plant but the inventory has been altered to assist in illustrating the methodology. The example is written as a guidance document to assist readers in understanding the calculations. It does not provide a sensible template for carrying out the calculations or presenting the results. There is software available to sites to assist in carrying out the calculations and presenting results. 1 See sections 6.2.2, 6.2.3 and 6.2.4 and/or figure 1, Process Flowsheet in EGPR02 NDA Prioritisation Process Worked Example, Safety & Environment Detriment Background Information: The facility being considered is a shutdown chemical plant. The inventory is contained in a fuel receipt pond, three chemical cells a process glovebox and sample stations and service gloveboxes. The building was split into two parts for contamination control. The smaller part, about 25%, was classified as a White/C2 area and operated in a clean mode. The larger area was classified as Amber/C3 has extensive low level fixed contamination. The plant was run down at the end of its last operational period but not washed out. Calculation of SED: The Safety & Environment Detriment can be calculated as the sum of the Radiological Potential Detriment, Chemical Potential Detriment plus the Ongoing Environmental Detriment multiplied by 1E+08. The individual parts are calculated below. Radiological Potential Detriment2 The radioactive inventory is classified into 4 waste streams within the plant and one for contaminated soil below and around the plant. The steam descriptions and relevant factors are given below. The justification for the Form and Control factors is given in Appendix 1. You are strongly recommended to use the format of the tables in appendix (taken from EGPR01 W01/02) to both decide on the Form and Control Factors and record the thinking for audit purposes. Justifications for the FD (Facility Descriptor), WUD (Waste Uncertainty Factor), SSR (Speed to Significant Risk), BER (Benefit of Early Redemption) and CU (Characterisation Uncertainty in Data and Projections) are given in Appendix 2. The RHPs (Radiological Hazard Potentials) have been calculated in the RHP Calculator version 4. Note. In this instance each stream is assumed to have one Form Factor at present, powder for solids. In practice some contamination will be fixed and could be classed a discrete or monolithic solid and the streams could be split into sub-streams by percentage. However in this instance that amount is likely to be relatively low and splitting it would not have major affect on the total Potential 2 Radiological Potential Detriment equals Σ((RHP) x (FD x WUD)4) + Σ((RHP) x (SSR x BER x CU)4) Detriment as the remaining powder would dominate. If you consider that the powder is only a small part of the contamination, say 10% or less, split the stream into sub-streams. Record what assumptions you have made. Waste Stream Description Form Factor Powder Control Factor Months RHP 01/04/07 2.44E+03 1 2 3.90E+04 FD WUD RPD Decommissioning Bulk LLW Decommissioning Supercompactable LLW Decommissioning RHILW Solvent (description in CPD) Pond Clean Up RHILW Remediation LLW Soil (Contaminated Land) Total Powder Months 6.97E+00 1 2 1.12E+02 Powder Liquid Liquid Liquid Months Decades Months Decades 8.50E+05 2.80E-02 4.38E+03 7.59E-02 SSR 1 1 1 1 BER 1 2 2 4 CU 4 1.36E+07 7.16E+00 1.12E+06 1.94E+01 1.48E+07 Note the calculations demonstrate that small inventory in the solvent (4E+2 TBq alpha and 1E+3TBq beta/gamma) does not make a significant difference to the result, in this case, can be ignored. The contaminated ground which has a comparable score is included as it will remain after the buildings initial SED Reduction Project. Practitioners can use judgement, backed by scoping calculations if required, to decide if there is value in including small inventories. Maintain a list of any inventories that are not included in the calculations. Chemical Potential Detriment3 The plant currently contains some mobile chemicals, approximately 100L of 4% tributyl phosphate (TBP) diluted in odourless kerosene (OK), 100L of 6% TBP in OK, 400L of aluminium nitrate/aluminium hydroxide (AL(NO3)3 /Al(OH)3) solution containing 1g/L mercury (Hg). There is 200L of zinc bromide solution stored in the plant. All asbestos lagging has been removed but the plant is clad in asbestos sheet. The plant has approximately 200te of lead (Pb) bricks. There is no known chemical contamination of the associated land. The total CPD for this plant is calculated in the following table. Note, information on the R phrases can be found in “Approved supply list, information approved for classification and labelling of substances and preparations dangerous for supply "Chemicals, hazard information and packaging for supply, amendment regulations 2002"”. This is available on the UKAEA Intranet by clicking on the document title on the Hazardous Substance Information page, http://intranetd/dd/Safety/Compliance/coshh_index.htm . In addition datasheets on non-radioactive materials held at Dounreay are kept in the Omnisafe database which is currently available to all sites through the UKAEA NAL. Material Mass R Phrases Extended COHMA Limit te 150 150 150 150 150 150 0.000067 CInv4 Stream Total CInv Form Factor Control Factor CHP5 FD WUD CPD6 OK 152kg R22 R65 R38 R41 R37 R22 0.001 0.00101 Liquid Decades 1.01E+3 1 4 2.59E+05 TBP 10kg 1 100,000 Chemical Potential Detriment equals Σ((CHP) x (FD x WUD)4) + Σ((CHP) x (SSR x BER x CU)4) CInv (COMHA Inventory) = Mass ÷ Extended COHMA Limit 5 CHP = 1E+11 x CInv x Form Factor ÷ Control Factor 6 CPD = CHP x (FD x WUD)4 4 3 Material Mass R Phrases Extended COHMA Limit te 50 5000 150 150 150 150 150 150 600 5 150 150 100 150 CInv4 Stream Total CInv Form Factor Control Factor CHP5 FD WUD CPD6 AL(NO3)3 54kg Oxidising R08 7 0.0011 Liquid Years R22 R34 Al(OH)3 46kg R36/38 R37 R40 R43 R51 R26/R27/R28 Mercuric Nitrate 0.4kg R36/R38 R33 R50/53 ZnBr Asbestos in sheeting Pb 500kg <500te ~200te R36/38 N/A R20/22 0.00031 0.00149 1 0.00008 10000 1.49E+5 1 4 3.81E+06 0.0033 0.0033 Liquid 1 Years 10,000 3.30E+4 1 4 8.53E+06 150 1.33 1.33 Discrete Decades 1.33 E+0 1 1 1.33E+00 7 Assumed to be same as aluminium nitrate apart from not being an oxidising material Material Mass R Phrases Extended COHMA Limit te 150 150 150 CInv4 Stream Total CInv Form Factor Solids 0.00001 Control Factor CHP5 FD WUD CPD6 R33 R61 R62 Total CPD 100,0000 1.25E7 To avoid trivial work practitioners need to be able to judge when it is worth calculating CHPs. The above results show that there is no need to calculate CHPs for stable solids until the facility RHP is reduced to low levels, >10. However, relatively small quantities of liquids may have a significant score for medium RHPs. For guidance 400g of a very toxic material, mercuric nitrate, in a liquid form with a CF of years gives a CHP of 2E+05. Ongoing Environmental Detriment8 The total electrical consumption for the year 2005/6 was 0.281GWh. Although there were decommissioning activities in progress none of the processes was heavy user of electricity hence this is a good approximation of the consumption required to comply with the site licence. It is possible that consumption could be reduced but this would require a major new safety case and so is excluded from consideration. OED x 1E+08 = 0.281 x 1E+8 = 2.81E+7 8 OED is the annual electrical consumption required for care and maintenance in GWh/y. It is multiplied by 1E+8 in the equation to calculate the SED Total SED Attribute RPD CPD OED x 1E+08 Total Score 1.48E+07 1.25E+07 2.81+E07 5.54E+07 The SED scores are used to rank the facilities, review the Initial Ranking List of projects to produce the Adjusted Ranking List9 and, when plotted against time, give the site progress curve10. 9 10 Step 7 EGPR02 Appendix 10 EGPR02 NDA Prioritisation Process Worked Example, Project Benefit Measure Background Information: This assesses the project that will carry out the Initial and Interim Decommissioning of shutdown fuel reprocessing plant. This is considered as a single project as the work is carried out as a single project without a hold point. At the start of the project the plant consists of a fuel receipt/preparation pond, three chemical cells, a process glovebox and sample stations and service gloveboxes. The pond has been emptied of fuel but still contains contaminated water and sludge. The processing plant was run down at the end of the last run but not washed out. The project addresses the hazard reduction of a number of waste streams rather than one as recommended in the NDA Prioritisation Audit11. This is because the project will tackle the entire plant inventory, apart from the contaminated ground, in an integrated series of operations. Note where a single waste stream was to be treated as a unit, typically conditioning of stored waste, this would normally be considered as separate project. Details of the starting inventory are given in the worked example on SED calculation. At the end of the project all radioactively contaminated material will have been removed and the building will be ready for demolition. The Low Level Waste (LLW) will be held in Half Height ISO containers awaiting final treatment and disposal, which is subject of a separate project. Remote Handleable Intermediate Level Waste (RHILW) will be held raw in an interim store prior to being conditioned by a different project. The TBP/OK will be stored in a different plant awaiting destruction and the other chemical streams will have been disposed of. Destruction of TBP/OK is the subject of a separate project. There is some contaminated ground associated with the building but this will not be affected by the project. Calculation of PBM The equation for calculating the PBM is: PBM = (∆HP vs t)+[FD+WUD+(∆LD vs t)]/3+[(∆HP vs £)+(∆OFC vs t)]/2+(∆OED vs t) Each term is calculated below. 11 Nuclear Decommissioning Authority, Overview Audit Report EGPR019 Hazard Reduction Attribute, ∆HP vs Time The table below shows the calculation of the ∆HP. The calculation of the initial RHP and CHP are shown in the worked example of the SED calculation. The initial values and final values are tabulated below. Justification for Form and Control Factors is contained in Appendix 1. Initial Conditions Final Conditions Waste Stream Description Decommissioning Bulk LLW Decommissioning Supercompactable LLW Decommissioning RHILW Pond Clean Up RHILW TBP/OK AL(NO3)3 Al(OH)3 ZnBr Form Factor Powder Control Factor Months RHP/CHP Form Factor Powder Discrete solids Control Factor Years RHP/CHP 2.44E+03 2.44E+02 Powder Months 6.97E+00 Decades 5.40E-08 Powder Liquid Liquid Liquid Liquid Months Months Decades Months Years 8.50E+05 4.38E+03 2.80E-02/1.01E+03 1.49E+05 3.30E+04 Powder Powder Liquid Decades Decades Decades N/A N/A 8.50E+03 1.82E+01 2.80E-02/1.01E+03 Initial Conditions Final Conditions Waste Stream Description Pb Total Form Factor Discrete Solids Control Factor Decades RHP/CHP Form Factor Control Factor N/A RHP/CHP 1.33 E+0 1.04E+06 9.52E+03 The reduction in the HP is 1.04E+6. The look-up tables use the log of the difference the HP which is 6. Note if the result was just below 1E+06, say 9.95E+05 the answer would be 5 as the PBM calculator rounds down not off. The project is in progress so the start date is taken as 1st April 2007. The finish date of this stage of the work in P3e is 21st November 2013 so the duration is 6 years. However this has been artificially constrained to meet annual funding requirements and the project team estimate that the project could be completed in 4 years. The prioritisation should not be distorted by funding constraints so the period for prioritisation purposes is taken as 4 years. Again to simplify the calculation do not round off the number of years. From the look-up table 1 EGPR02 this gives a score of Hazard Reduction Attribute score of 82. Safety and Security Management Attribute, (FD+WUD+(∆LD vs t)) ÷ 3, The derivation of the FD and WUD are given in the SED worked example appendix 2. The FD for the entire building is category 10, score 1. The WUD categories are 9 and 8. The worst case should dominate so the building WUD category is 8, score 4. Note the contaminated ground is not counted because it is not directly affected by this project. If the contaminated ground dominated the SED the project boundaries should be drawn to include the remediation of the contaminated ground. If the contaminated ground was included it would score (SSR+BER+CU) x 3; in this case (2+2+4) x 3 = 24. Note this would not be added to the FD + WUD score but, as it is greater, it would replace it. There is no measured legacy dose from the care and maintenance of this facility so the ∆LD vs t score is 0, see look-up table 3 in EGPR02 Hence the Safety and Security Attribute score is (1 + 4 + 0) ÷ 3 = 2 Value for Money Attribute, [(∆HP vs £)+(∆OFC vs t)]/2 The log ∆HP is 6, see above. The project costs are extracted from PMRS. Use the datasheet output and combine the base and contingency cost. The project consists of the following CWBS elements: CWBS Element Preparation Activity Work Description Prepare and review safety documentation 2007/08 Prepare and review safety documentation 2008/09 Prepare and review safety documentation 2009/10 Decommissioning & Dismantling Support (maintenance and HP surveys) Total Less OFC of say £200k/y for 4 years Project Cost All activities from 01/04/2007 Activities between 2007 & 2010. Note These are time dependant so are assumed to stop in 2010 when the project could be finished if there were no financial constraints. £k 51 51 51 6060 2160 8373 800 £7,573k Note the costs do not take into account the receipt of the IL wastes into the interim stores or receipt and processing of LL waste as these are site services which cannot be sensibly allocated between the projects. Such accounting rules must be applied consistently across all the projects on a site. The project cost is in the £7M band and with a log ∆HP of 6. This gives a score of 100 in look-up table 2 EGPR02. The care and maintenance costs for the plant are not separated out in the WBS so the costs are not directly available. For a plant of this size one would expect that care and maintenance could be achieved by 3FTEs and no major refurbishment would be expected in the likely future. Allowing for consumables would put the costs in the £125-250k/y band, which with a 4 year duration scores 0, see look-up table 4 EGPR02. If a major refurbishment was likely the costs should be spread over the potential life and added to the annual C&M costs. Note for a duration of 4 years the score would be zero until the annual C&M costs exceeded £500k and at £2.5M/y would only add 3 to the final score and at £10M the would only add 5. Hence for most facilities it is acceptable to make rough estimates of the C&M costs. The estimates can be refined if you require to differentiate between two projects with similar scores. Hence the Value for Money Attribute = [(∆HP vs £) + (∆OFC vs t)]/2 = (100 + 0) ÷ 2 = 50 Ongoing Environmental Detriment Attribute, ∆OED vs t The total electrical consumption of the plant for the year 2005/06 was 0.281GWh. The minimum band in the look-up table 5 EGPR02 is 1GWh/y. In this band any project with duration of more than a year scores 0. Hence the Ongoing Environmental Detriment score is 0 Total PBM Score Attribute Hazard Reduction Safety & Environmental Management Value for Money Ongoing Environmental Detriment Total Score 82 2 50 0 134 The PBM scores are used to rank the projects producing the Initial Ranking List (IRL). The IRL is converted to the Adjusted Ranking List (ARL) to allow for any high SED facilities that do not have high scoring SED Reduction projects. The ARL is used to produce or review the first draft schedule. These actions are covered in steps 6 to 12 in EGPR02. Appendix 1 Determination of Form and Control Factors Radioactive Inventory Notes. This example follows the Dounreay naming conventions, i.e.: Arisings Raw Stock Conditioned Stock Material that is currently in a facility and is not classed as waste but will be converted to waste in the future, e.g. contaminated building fabric or equipment. Material that is classed as waste that has not been conditioned for disposal or export. This will include RHILW in interim storage and bulk LLW in HHISOs. Waste that has been conditioned for disposal. This includes supercompacted LLW which is to be grouted as part of the disposal process. Note that there is no difference between Raw and Conditioned Stock for wastes that are untreated apart from grouting at the disposal point. This applies to Bulk LLW and ILW in NIREX 2m and 4m boxes Once disposed of or removed from the site material given a RHP of zero and Form and Control Factors are not relevant. Note where there are no storage features identified the Control Factor will be Decades Radiological Inventory Storage mode Decommissioning Bulk LLW Contaminated Material Properties Heat Corrosive Flammable No No No Storage Features Control/Form Factor Arisings: Form Factor = Powder Some of the contamination is Storage mode Material Arisings part of building structure, gloveboxes, plant items etc. Stock in HHISOs Material Properties Corroding Arisings: The building is subject to weathering but is robust and would only require an occasional inspection to ensure there was no deterioration that could lead to a release Raw Stocks: The HHISOs will be stored in a weather proof building until disposed of. Very infrequent inspection will ensure they do not deteriorate significantly Storage Features Building and Package Inspection Pond level checks Arisings: Annual inspection of the building is required to prevent potential losses. This would normally give a control factor of years but as some of the waste will be in the pond fabric and containment of surface contamination relies on the water level this will require checking every few months Raw stocks: Annual package inspection is sufficient to ensure packages do not corrode Control/Form Factor contained in liquid in equipment but it is all assumed to be powder as this will dominate the RHP. Control Factor = Months Raw Stock: Form Factor = Powder Bulk material will be stored with minimum conditioning Control Factor = Years Secondary React water React gas Other No No No Pond Level Drop The pond is above ground and a leak or extensive evaporation would allow material to dry out leading to a release. Deterioration of the pond waterproof lining could result in a slow leak. Water Level Checks and top ups Arisings Checks on the pond every few months are required to prevent the level dropping excessively Storage mode Material Properties Heat No No No as Bulk LLW No No No As Bulk LLW Storage Features Control/Form Factor Arisings: Form Factor = Powder As Bulk LLW Control Factor = Months As Bulk LLW Raw Stock: Form Factor = Discrete Solids Decommissioning Supercompactable LLW Contaminated material Arisings currently part of building structure, gloveboxes, redundant plant etc After project the material will be supercompacted and stored in HHISOs Corrosive Flammable Corroding Secondary React water React gas Other Water Top Up As Bulk LLW Waste will be supercompacted soon after being produced. Supercompaction will enclose the contamination. Control Factor = Decades No mechanism for pucks to escape Storage mode Decommissioning RHILW Material Properties Heat Corrosive Flammable No No No Storage Features Control/Form Factor Arisings: Form Factor = Powder Contaminated material Storage mode Contaminated solids The waste will be transferred on arising to the current raw waste stores Material Properties Corroding Arisings Material in cells or pond which will be stable for months Raw Stock Material packaged in SS drums in engineered store. No mechanism for decay No No No Pond Level Drop Storage Features Waste Inspection Arisings As Bulk LLW Control/Form Factor defaults to powder Control Factor = Months Material in cells or pond which will be stable for months Raw Stock: Form Factor = Powder Control Factor = Decades Raw Stocks No features identified Secondary React water React gas Other Water Top Up As Bulk LLW Storage mode Pond Clean Up RHILW This material is currently the pond liquor Material Properties Heat Corrosive Flammable Corroding Secondary React water React gas No No No No No No No Storage Features Control/Form Factor Arisings: Form Factor = Liquid Control Factor = Months Raw Stock: Form Factor Powder Storage mode Material Properties Other Arisings Pond Level Drop The pond is above ground and a leak or extensive evaporation would allow material to dry out leading to a release. Deterioration of the pond waterproof lining could result in a slow leak. Raw Stock Material will be in stainless steel containers in an store designed for long tem storage with no practical mechanism for release Storage Features Water top up Arisings Inspection / top-up of water every few months is sufficient to replace evaporative losses and check for slow leaks Raw Stock No features identified Control/Form Factor Ion exchange material is powdery Control Factor = Decades Storage mode Remediation LLW Soil Arisings: Soil under and around the plant Material will go straight to disposal so Stock not applicable Material Properties Heat Corrosive Flammable Corroding Secondary React water React gas No No No No No No No Storage Features Control/Form Factor Arisings: Form Factor = Liquid Pessimistically assumed as watery sludge following NEXIA advice Control Factor = Decades No evidence of movement towards the site boundary Storage mode Material Properties Other Migration to aquifer due to ground water movement Storage Features Monitoring After monitoring for some years there is no evidence of migration. Although reassurance monitoring is still performed there is now confidence that the contamination will remain immobile for decades. Control/Form Factor Chemical Inventory Storage mode TBP/OK Material Properties Heat Corrosive Flammable Corroding Secondary React water React gas Other No No Does not require active suppression No No No No No Storage Features Control/Form Factor Arisings and Raw Stock: Form Factor = Liquid Control Factor = Decades Material in s/s tanks with no means of release. No storage features identified Storage mode AD/Al Solution stored in Material Properties Heat Corrosive Flammable No No No Storage Features Control/Form Factor Arisings: Form Factor = Liquid Storage mode double skinned stainless steel containers Material Properties Corroding Will very slowly corrode stainless steel at ambient temperatures. No No No No Storage Features Inspection Annual inspection is required to ensure that there is no bulk loss of material Control/Form Factor Control Factor = Years Raw Stock: N/A Secondary React water React gas Other Storage mode ZnBr Solution stored in Stainless steel Containers Material Properties Heat Corrosive Flammable Corroding No No No May very slowly corrode stainless steel at ambient temperatures. No No No No Storage Features Control/Form Factor Arisings: Form Factor = Liquid Inspection Annual inspection is required to ensure that there is no bulk loss of material Control Factor = Years Raw Stock: N/A Secondary React water React gas Other Storage mode Lead, bricks and sheet Material Properties Heat Corrosive Flammable No No No Storage Features Control/Form Factor Arisings: Form Factor = Discrete Solids Storage mode Material Properties Corroding Secondary React water React gas Other No No No No No Storage Features Control/Form Factor Control Factor = Decades Stable material no mechanism for dispersion Raw Stock: N/A Appendix 2, Determination of FD and WUD, SSR, BER, CU FD: The facility has an extant modern standards decommissioning safety case with all significant forward programme items complete or being followed up. The building has been substantiated to last well beyond any likely decommissioning period. The parts that contain the loose contamination are robust and would survive a design basis accident. The containment levels are adequate for the inventory. The majority of the inventory is within the cells or gloveboxes or the pond. The cells and gloveboxes are ventilated and the pond has the pond water plus a containment building. The plant has had a new modern standards ventilation system. There is a leak in the pond wall but it is above the care and maintenance water level. There is contamination outside the double containment areas but it is low level and fixed in building fabric so the containment level is not relevant. There are no defects that could lead to a major release. There is no requirement for contingency; the pond contamination level is too low to cause a major problem and the other material is not sufficiently mobile to require a contingency. The facility failure would not have a significant effect on major hazard buildings or be adversely affected by failure of the buildings. The facility is given the lowest FD category of 10 (FD score 1). This applies to all the inventory areas. WUD: All wastes are raw but all are stable and none are reactive. There is no potential for a criticality. The wastes are monitored and managed. The location of all the wastes is known and although the extent of contamination is sufficiently known for safety and management purposes. The solid material is given WUD category 9 (WUD Score 2) but the pond liquor and liquid chemicals being more mobile is given a lower WUD category of 8 (WUD score 4). SSR: The contaminated land around and under the plant is only a few meters from an aquifer. If the contamination reached the aquifer the material could reach the site boundary within 40 years. However, the contamination has been present for decades and there is no sign of migration. If the material did reach the site boundary it would not present a significant risk. Hence the SSR is Low (Score 1). BER: As there is no significant risk there is no benefit in early reduction, hence the BER is Low (score 1) CU: The site has a monitoring regime that covers all key species and major pathways but not all; hence score 2 for monitoring of current situation. The site is sufficiently characterised to show key site features so scores 2 for Prediction of Site Evolution. This gives a CU figure of Medium and a score of 4.