IAEA International Conference on the Safety of Radioactive ... Documents/Session 3a - DSRS...24 november 2016 iaea international conference on the safety of radioactive waste management

IAEA International Conference on the Safety of Radioactive Waste Management

Institute of Radiation Protection and Dosimetry - IRD

Laís Alencar de Aguiar [email protected] / [email protected]

Vienna, Austria, 21–25 November 2016

BOREHOLE DISPOSAL OF DSRS IN BRAZIL

mailto:[email protected]



This paper presents the overview of the IAEA TCP (2014-2015) development concerning the feasibility of the BOSS concept for the Brazilian DSRS inventory, including safety and legal considerations.

24 November 2016 IAEA International Conference On The Safety Of Radioactive Waste Management 2

Project Team and affiliation:

Nuclear and Energy Research Institute (IPEN), São Paulo, Brazil

Eduardo Ferreira Goro Hiromoto Júlio Marumo Roberto Vicente

Nuclear Technology Development Center (CDTN), Belo Horizonte, Brazil

Carlos Carvalho Filho

Francisco Rios Heidar Gharbieh

Igor Pereira Radioprotection and Nuclear Safety Board - Brazilian Nuclear Energy Commission (CNEN), Rio de Janeiro, Brazil

Flávia Schenato Laís Aguiar

Paulo Rodrigues Sônia Prates Stela Cota

The Brazilian Nuclear Energy Commission is a federal agency, created in 1962 (Law #4118), with administrative and financial autonomy and legal personality under public law, which has the following institutional purposes:

I. Support development of the National Nuclear Energy Policy; II. Perform actions for research, development, and provision of nuclear technology and its

applications for peaceful purposes as provided in Federal Law #7,781 (1989), and III.Regulate, license, authorize, supervise and control such use.

The Brazilian Nuclear Energy Commission - CNEN - is the governmental body responsible for the final disposal of radioactive wastes in the whole country. The promulgation of regulation

concerning waste management and disposal is also a responsibility of CNEN.

Brazilian Nuclear Energy Commission - CNEN

IAEA INTERNATIONAL CONFERENCE ON THE SAFETY OF RADIOACTIVE WASTE MANAGEMENT 3 24 November 2016

Brazilian Nuclear Energy Commission –

CNEN

Radioprotection and

Nuclear Safety

Regulatory Body

Standarts and Guidance

Medical, Industries Facilities

Nuclear Reactors

Waste Management

and Disposal

Fuel Cicle Facility

Raw materials and

Minerals

Safeguards and

Physical Protection

Research and

Development

Research Centres

and Laboratories

CDTN

IEN

CRCN-NE

IPEN IRD

LAPOC

Institutional Management


Laboratories:

DSRS are stored at four nuclear research

institutes of CNEN

Brazilian Inventory Of Disused Sealed Radioactive Sources

MAIN SOURCES IN THE BRAZILIAN DSRS INVENTORY ON 31/12/2014


Quantity (unit)

Radionuclide Half-life Activity

(y) (Bq) (%)

267 Am-241(1) 432.2 8.3E+12 0.8

105 Am-241-Be(1) 432.2 8.7E+12 0.9

8 C-14(1) 5730 1.6E+07 < 0.05

15 Cf-252(1) 2.64 2.8E+08 < 0.05

2,093 Co-60(1) 5.27 8.6E+14 87.9

3,098 Cs-137(1) 30 9.6E+13 9.8

5,114 Ir-192m2(1) 241 1.4E+08 < 0.05

3,429 Ra-226(1) 1600 5.5E+11 0.1

95,454 Am-241(2) 432.2 4.8E+11 < 0.05

73,680 Am-241(3) 432.2 1.2E+09 < 0.05

4,365 Ra-226(2) 1600 1.8E+10 < 0.05

264 Ra-226(3) 1600 8.0E+04 < 0.05

1,501 Others(1) 4,7E+12 0.5

Total

189,393 9.8E+14 100

(1) Radioactive sources from medical, industrial and research applications

(2) Radioactive sources attached to lightning rods

(3) Radioactive sources attached to smoke detectors

A total of 29 radionuclides have been identified in storage facilities for DSRS in Brazil.


Brazilian DSRS Inventory

1.00E+04

1.00E+06

1.00E+08

1.00E+10

1.00E+12

1.00E+14

1.00E+00 1.00E+01 1.00E+02 1.00E+03

Am-241

Ba-133

Cd-109

Cf-252

Cm-244

Co-60

Cs-134

Cs-137

Fe-55

H-3

Kr-85

Ir-192m

Na-22

Ni-63

Pm-147

Pu-238

Ra-226

Ru-106

Sr-90

Ti-44

Tl-204

C-14

Clearance

60Co

241Am

226Ra

137Cs

85Kr

3H

90Sr 63Ni

238Pu

147Pm

244Cm

Source half-life (y)

Sou

ce A

ctiv

ity

(Bq

)

Preliminary Site Selection

The approach for site evaluation for a borehole repository carried out in this project is presented in a specific paper “Borehole Disposed of Sealed Sources: Methodological proposal for the site

selection of a borehole repository in Brazil” (Poster 181)


Site selection, in consonance with CNEN regulation CNEN-NN-6.06, must follow a technical evaluation based on different

mapping scales.

Site Selection for the Radioactive Waste Disposal Facilities

CNEN NN 6.06:1989

Disposal facilities (near surface repository)

LILW (Short lived)

Site Selection for the Radioactive Waste Disposal Facilities

Regions of Interest

Preliminary Sites

Potential Sites

Candidate Sites

Preferred Sites

Regional Analysis

Technical Analysis

Screening Comparison and Ranking

Rejected Regions

Rejected Sites

Rejected Sites

Rejected Sites

The preferred site must be on government land

Factors for selecting a suitable disposal site:

a) Ecological b) Socioeconomic c) Geological d) Physiographic

IAEA INTERNATIONAL CONFERENCE ON THE SAFETY OF RADIOACTIVE WASTE MANAGEMENT

CNEN NN 6.06:1989

8 24 November 2016


The preliminary safety assessment developed was strongly based on the generic safety assessment (GSA) performed by:

Preliminary Safety Assessment

For unknown or not yet defined issues (such as site-specific geosphere characteristics), the definitions used in GSA were maintained.

no attempt was made in this report to adjust the dimensions of the borehole components to allow physical fitting of all the Brazilian inventory.

LITTLE, R.H., VAN BLERK, J.J., WALKE, R.C., BOWDEN, R.A., Generic Post‐Closure Safety Assessment and Derivation of Activity Limits for the Borehole Disposal Concept, Quintessa Report QRS‐1128A‐6 v2.0, Quintessa Limited, Henley‐on‐Thames. 2004.

INTERNATIONAL ATOMIC ENERGY AGENCY, Generic Post‐closure Safety Assessment for Borehole Disposal of Disused Sealed Sources. IAEA Draft Safety Report, International Atomic Energy Agency, Vienna. 2013.

Important


Quantity (unit)

Radionuclide Half-life Activity

(y) (Bq)

169,506 Am-241 432.2 1.75E+13

7 Ba-133 10.7 1.02E+07

15 Cf-252 2.64 2.76E+08

7 Cm-244 18.11 8.34E+09

2,093 Co-60 5.27 8.58E+14

3,098 Cs-137 30 9.59E+13

57 Fe-55 2.7 2.73E+09

118 H-3 12.4 7.93E+11

1 K-40 1.28E+09 6.29E+04

327 Kr-85 10.7 1.94E+12

121 Ni-63 96 7.78E+10

227 Pm-147 2.62 5.57E+10

4 Pu-238 2.41E+04 3.11E+09

8,067 Ra-226 1600 5.83E+11

271 Sr-90 29.1 1.46E+11

3 Th-232 1.40E+10 1.39E+05

1 Ti-44 47.3 2.17E+07

63 Tl-204 3.78 5.14E+08

1 U-238 4.47E+09 8.51E+03


5 Scenarios: 1 Design 4 Defects

Flow Rate: • High • Medium • Low

Saturated disposal zone in a porous system

Considering the current Brazilian inventory and the results of IAEA (2013) document

The results of the IAEA (2013) document have shown that the most restrictive activity limits were obtained

for the saturated disposal zone with high flow rate in a porous system, with Pu‐238, Pu‐239 and Am‐241 the

most limiting radionuclides.



The AMBER software tool was used for the preliminary safety assessment of a Brazilian borehole repository.

The same model developed by Quintessa and implemented in the IAEA (2013) document was used with the same data, except for the inventory and radionuclide‐specific factors (CNEN regulation).

The impact on the safety assessment results, excluding all 241Am sources from the present inventory, was also addressed and has shown that the dose rates for all cases were below the dose constraint.

Among all design and defect scenarios, the results have shown that the only case in which the predicted dose exceeded the dose constraint of 0.3 mSv/y was for high flow rates condition in the porous system,

with the 241Am chain responsible for the highest dose rates.


Medium flow rates

High flow rates

Low flow rates

Dose Constraint

Dose Constraint Dose Constraint


Legal & Regulatory Framework

Federal Law 10,308 (2001)

Establishes rules for the site selection, construction, operation, licensing and control, financing, civil liability and guaranties related to the storage and disposal of radioactive waste.

APPLIES TO:

The storage and disposal facilities will be built, licensed, operated and managed according to criteria, procedures and standards established by CNEN.

CNEN is responsible for designing, building and operating radioactive waste disposal facilities (repositories).

Storage Facility Disposal Facility

ALLOWS FOR:

In compliance with National Radioactive Waste Act (Law 10.308), CNEN issued the:

Establishes general criteria and basic requirements for the licensing process of storage and disposal facilities for LILW.

Also includes the classification of radioactive waste according to the levels of radiation, based on the IAEA General Safety Guide #GSG-1 (2009), as well as disposal methods.

CNEN NN 8.02:2014


CLASS CHARACTERISTICS CLEARANCE OR

DISPOSAL

0. Exempt Waste Activity levels or activity concentration at or below clearance levels established by CNEN .

(CNEN NN 8.01 – Radioactive Waste Management for LILW) unrestricted

1. Very Short Lived Waste Very short lived radionuclides (half-life ≤ 100 days) and activity levels or activity concentration above

clearance levels.

Decay storage and subsequent

clearance

2. Low and Intermediate

Level Waste Activity levels or activity concentration above clearance levels and thermal power below 2 kW/m3.

2.1 Short

Lived Waste

Short lived beta/gamma emitting radionuclide (half-life ≤ 30 years) and restricted long lived

radionuclide concentration (limitation of long lived alpha emitting radionuclides to 3700 Bq/g for

individual waste packages and an average of 370Bq/g for a group of waste packages).

Near Surface Disposal

2.2 and 2.3

NORM

Waste containing radionuclides of U and Th decay series from the oil/gas industry and general mining

industry, respectively, with activity levels or activity concentration above clearance level.

Near Surface Disposal or

below surface defined by safety

assessment

(NORM packaged)

2.4 Long

Lived Waste Long lived alpha emitting radionuclides in concentrations exceeding limitations for short lived waste. Geological Disposal

3. High level Waste Thermal power above 2 kW/m3 and long lived alpha emitting radionuclides in concentrations

exceeding limitations for short lived waste. Geological Disposal

Radioactive Waste Classification – CNEN NN 8.02:2014 (based on GSG-1:2009, IAEA)


2.1

Predisposal (storage)

Disposal

CNEN NN 8.02

2.2 2.3 2.4 2.1

2.1 short lived waste

2.2. and 2.3 NORM (packaged)

2.4 long lived waste

administrative actions:

Radioactive Waste Class 2 (LILW):

IAEA INTERNATIONAL CONFERENCE ON THE SAFETY OF RADIOACTIVE WASTE MANAGEMENT 16

Licensing of storage and disposal facilities for LILW

24 November 2016


The design and construction of a near surface disposal facility for LILW has been defined as priority of the National Nuclear Program.

However, considering the Brazilian DSRS inventory, many of these sources may not meet the waste acceptance criteria for near surface disposal in compliance with requirements of Brazilian regulations.

High activity sources containing 60Co, 137Cs and 90Sr may not be suitable for shallow disposal or decay to exemption levels during a conventional institutional control period (~300 years), thus representing a possible hazard in a near surface repository.

Furthermore, a large number of 241Am sources and other long-lived radionuclides, such as 226Ra, are of particular concern for disposal of Brazilian inventory, since longer half-life sources might require a greater degree of isolation and depth superior to 30 m normally associated with near surface disposal. The depth required for disposal will depend on the host geology of a specific site and the amount of waste to be disposed of.

Legal & Regulatory Framework

Comments (1/3)


In the current Brazilian DSRS inventory, 241Am is the largest subcategory of sources with roughly 170,000 units; however, the future inventory remains unknown.

The dimension of the borehole repository has not yet been defined. In particular, decisions associated to the size of the disposal container have still to be made which in turn will influence the depth of the borehole.

Moreover, since the Brazilian DSRS inventory is relatively large, it may be necessary to implement more than only one borehole.

Comments (2/3)


Since the Brazilian inventory is relatively large compared to the inventories presented in IAEA (2013) and Little et al. (2004) documents, the large configuration (capsule and containment barrier) could be considered for the Brazilian borehole repository in order to minimize its depth.

The typical BOSS depth was indicated to be around 100 m [IAEA (2013), Little et al. (2004), IAEA (2004a) documents]. Nevertheless, greater borehole depths must be evaluated to fit the whole Brazilian DSRS inventory.

The safety assessment of a Brazilian borehole repository is regarded as a preliminary assessment with a high level of uncertainty.

Comments (3/3)


All range of activities and radionuclides intrinsic to national inventory of DSRS may require the establishment of further requirements and appropriate approach for long-term safety disposal and acceptability of other disposal concepts.

Concerning Brazilian regulatory framework, a more specific regulation is required aiming to provide safety requirements for a licensing process applicable to disposal of other classes of waste (e.g. long-lived LILW):

(a) waste acceptance criteria such as conditioning and packaging of high activity sources and Long-lived LILW;

(b) site selection process following predetermined criteria, aiming the siting of the suitable host geology for other disposal options;

(c) timescales for licensing including the period of active and passive institutional control.

The authors are very grateful to:

The Brazilian Nuclear Energy Commission – CNEN: Nuclear Technology Development Center (CDTN) Nuclear and Energy Research Institute (IPEN) Radioactive Waste Management Division (DIREJ) Institute of Radiation Protection and Dosimetry (IRD)

The International Atomic Energy Agency – IAEA, in particular Stefan Joerg Mayer

The Quintessa Limited Company, in particular Richard Little


Acknowledgments

Laís Alencar de Aguiar, D.Sc. Institute of Radiation Protection and Dosimetry - IRD

[email protected] / [email protected]

Vienna, Austria, 21–25 November 2016


