1. 上海核工程研究设计院 www.snerdi.com.cn
Study on Plume Emergency Planning Zone determination for CAP200 Small Modular Reactor
Wang Xuan
Shanghai Nuclear Engineering Research & Design Institute
International Conference on Topical Issues in Nuclear Installation Safety: Safety Demonstration of Advanced Water Cooled Nuclear Power Plants，June 2017
上海核工程研究设计院

2. Intellectual Property Rights Statement
知识产权声明
本文件的知识产权国家电力投资集团公司及其相关产权人所有，并含有其保密信息。对本文件的使用及处置应严格遵循获取本文件的合同及约定的条件和要求。未经国家电力投资集团公司事先书面同意，不得对外披露、复制。
Intellectual Property Rights Statement
This document is the property of and contains proprietary information owned by SPIC and/or its related proprietor. You agree to treat this document in strict accordance with the terms and conditions of the agreement under which it was provided to you. No disclosure or copy of this document is permitted without the prior written permission of SPIC.

3. General methods and criteria Site overview Accident type
Contents
Introduction
General methods and criteria
Site overview
Accident type
Methods and parameters
Results
Prospect

4. Assembly and accountability
1.Introduction
There are four emergency categories in NPP based upon the severity of the accident and the expected doses:
Emergency standby
Plant emergency
Field area emergency
Off-site emergency
Whenever the health and safety of site workers and members of the public may be jeopardized, urgent protective actions (as well as others) need to be taken.
Evacuation
ITB
Other
Assembly and accountability
Sheltering
on-site
urgent protective actions
Evacuation
ITB
Other
Traffic Control
Sheltering
off-site

5. 1.Introduction Taking Urgent Protective Actions
In order to facilitate the decision whether to implement or not certain protective actions, Intervention levels have been established. These are values of avertable dose that, if exceeded, protective actions should be performed. Urgent Protective Action Intervention Levels are shown in the following table:
Protective Action
Suitable Sustained Duration (Days)
Intervention Level
Sheltering
<2
10 mSv
Evacuation
<7
50 mSv
Stable Iodine Intake -
100 mGy
(Projectable dose for thyroid gland)
Taking agricultural countermeasures
Contamination levels of food and drinking water will be assessed and compared with the following generic action levels for stopping and replacing the specific food and drinking water:
Radionuclides
Foods destined for general consumption (kBq/kg)
Milk, infant foods and drinking water (kBq/kg)
134Cs, 137Cs, 103Ru, 106Ru, 89Sr 1
131I
0.1
90Sr
241Am，238Pu，239Pu
0.01
0.001

6. 1.Introduction Emergency Planning Zone of China（ GB/T 17680.1-2008 ）
On-site Emergency Plan
Off-site Emergency Plan
3-5 km
Evacuation Zone
7-10 km
Shield Zone
30-50 km
Ingestion Planning Zone

7. 1.Introduction EPZ of China Nuclear Power Plants Nuclear Power Plant
Internal plume EPZ
External plume EPZ
Ingestion EPZ
Qinshan
5km
7km
30km
Daya bay
10km
50km
Hongyanhe
Yangjiang
Fangchenggang
Taishan
Ningde
Tianwan
4km
8km

8. 1.Introduction
According to the requirements of NNSA, design of SMR should meet the following guidelines:
Design can actually eliminate large releases.
Can cancel off-site interventions from the aspect of technical level, no need to set LPZ and EPZ.

9. 1.Introduction Design can actually eliminate large releases
Inherent safety and passive safety systems, such as the elimination of large LOCA accidents, control rod ejection accidents, etc, to reduce the possibility of accidents.
Even if the nuclear accident occurred due to extreme events, the radioactive will not be released to the environment in a large amount. The influent area of the accident will not exceed EAB of nuclear power plant.
Nuclear power accidents can not be completely eliminated, but even after the severe accident such as core melting, its impact is within the economic loss, and will not affect surrounding environment and lives.

10. SMR accidents impacts are within site boundary
1.Introduction
Can cancel off-site interventions from the aspect of technical level
Safety Objectives
LPZ
Plant
CAP200 SMR Plant
EPZ
Exclusion Area Boundary
EAB
Emergency Planning Zone(Plume)
EPZ
Low Population Zone
LPZ
EAB(500m)
Emergency Planning Zone(Ingestion)
EPZ
SMR accidents impacts are within site boundary

11. Nuclear Power Plant Requirements
1.Introduction
Nuclear Power Plant Requirements
SMR Requirements
Exclusion Area Boundary
EAB
postulated siting accident: EAB dose should not exceed 0.25Sv within 2h. LPZ dose should not exceed 0.25Sv during 30d. Collective dose should not exceed 2 × 104 person · Sv within 80km.
infrequent accidents: LPZ effective dose limit is 5mSv, thyroid dose limit is 50mSv.
limiting accidents: LPZ effective dose limit is 0.1Sv, thyroid dose limit is 1Sv.
≥500m
infrequent accidents: site boundary effective dose limit is 5mSv within 30d.
limiting accidents: site boundary effective dose limit is 10mSv within 30d.
severe accidents: site boundary effective dose limit is 10mSv within 30d.
Low Population Zone
LPZ
(GB6249)
≥5000m
Emergency Planning Zone(Plume)
EPZ(GB/T )
GB18871
Sheltering, <2d, 10mSv
Evacuation, <7d, 50mSv
Stable Iodine Intake,100mSv
3~5km Internal
7~10km
External

12. Non-technical factors
2.General methods and criteria
Deterministic method
Probability method
Determining accidents type
Source term
Meteorological data
Model
Parameters
Non-technical factors
Analysis
Action level
Plum EPZ
Ingestion EPZ
Step of determining emergency planning zone

13. 2.General methods and criteria
The regulations regarding this requirement are the following:
Criteria for emergency planning and preparedness for nuclear power plants-Part1: The dividing of emergency planning zone, GB/T
Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants, NUREG-0396
Basic Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources, GB
White paper for the establishment of the Small Modular Reactor Emergency Response Plan zone issued by NEI
Principles for the Safety Review of SMR(Trial)

14. 2.General methods and criteria
NUREG-0396 noted that at the recommended emergency planning zone boundary, the probability of dose exceed the corresponding intervention level should be less than 30% during the entire core melt accident sequence.
The NEI White Paper states that the cutoff probability of a severe accident can be 1E-07 / year in the case of a SMR emergency planning zone determination.
"Principles for the Safety Review of SMR(Trial) in China“ states: Under the condition of not taking off-site interventions, the public should be provided with higher off-site intervention levels than large PWR nuclear power plants. For an important sequence of the beyond design basis accident, the effective dose for individuals (adults) at the site boundary should be less than 10 mSv throughout the entire accident.

15. 3.Site overview
In the paper, Shandong Shidaowan nuclear power plant site is chosen as an case study site, to illustrate the calculation process of CAP200 SMR plume EPZ. Shidaowan nuclear power plant site is located in Weihai City, Shandong Province.
The site's dominant wind direction is SSW, calm wind frequency is 3.9% and the average wind speed is 3.63m/s.

16. 4.Accident type
The core inventory of CAP 200 is calculated using the "total amount of radioactivity at the end of the compact reactor cycle", which has the similar severe accident prevention and mitigation strategy as the CAP1000 reactor type and a similar containment leak rate.
The severe accident source term of CAP200 reactor contains six release classes.

17. 4.Accident type CAP200 severe accident release categories release type
name
description
frequency（/reactor.yr） IC
Complete containment
The containment remains intact, and conventional leaks cause the release of radionuclides into the environment.
1.78E-07 BP
Containment bypass
Containment failure occurs before the core damage, fission products from the reactor coolant system through the secondary circuit or other connecting system into the environment.
6.53E-09 CI
Containment isolation
Containment failure occurs before the core damage, because the failure of closure of the containment or the valve, leading to fission product release.
3.19E-10
CFE
Early failure of containment
The release of fission products into the failing containment is caused by a dynamic severe accident after the core has melted (before core collapse).
9.05E-09
CFI
Medium term containment failure
The release of fission products to the failure containment was caused by a dynamic severe accident after the core was melted (after the collapse of the core, 24 h before).
2.08E-10
CFL
Late containment failure
The release of fission products to the failure containment was caused by a severe accident after 24 hours.
5.96E-11

18. 5.Methods and parameters
When calculating CAP200 plume EPZ, MACCS2 computer program is used. The MACCS2 program was developed by the US Sandia National Laboratories for the US Nuclear Regulatory Commission (NRC), its purpose is to calculate the off-site consequences of severe accidents.

19. 5.Methods and parameters
Radionuclide core inventory and chemical group.

20. 5.Methods and parameters
Release plume segments and fractions for IC accident.

21. 5.Methods and parameters
Atmospheric diffusion parameters
Stability
Horizontal diffusion parameter
（σy= axb）
Vertical diffusion parameter
（σz= cxd） a b c d A
0.300
0.933
0.143
0.972 B
0.247
0.931
0.176
0.871 C
0.218
0.919
0.197
0.784 D
0.169
0.906
0.209
0.725 E
0.115
0.909
0.140
0.723 F
0.093
0.896
0.119
0.678

22. 5.Methods and parameters
Mixing layer height
Stability A B C D
Mixing layer. height（m）
900
350
200
The Monte-Carlo sampling method is used to classify the meteorological data. The weather classification is divided into 32 classes, and four representative weather series are extracted from each category. Therefore, the total number of representative weather series are 128.

23. Mean particle diameter(mm) Wet deposition rate(cm/s)
5.Methods and parameters
Radionuclide deposition
According to US SOARCA research project, 10 sets of particle deposition rate were given.
Wet deposition was calculated combined with radionuclide type and rainfall intensity.
Mean particle diameter(mm)
Wet deposition rate(cm/s)
0.15
0.153
0.29
0.049
0.53
0.064
0.99
0.11
1.8
0.21
3.4
0.43
6.4
0.84
11.9
1.4
22.1
1.7
41.2

24. 5.Methods and parameters
Surface roughness
Surface roughness is related to land use near the site
Land use
Roughness(cm)
Grassland 1
Field
10-15
Rural 30
Suburbs
100
Forest
20-200
City

25. 6.Results
Distance(km)
Mean peak dose(Sv)
0.12
1.65E-02
0.3
8.67E-03
0.4
6.44E-03
0.5
4.74E-03
0.6
3.56E-03
0.7
2.95E-03
0.8
2.54E-03
Results show that at the boundary of CAP200 site(500m), the mean effective dose is 4.74mSv, which is below 10mSv.

26. Dose exceeding Probability
6.Results
Distance(km)
Dose exceeding Probability
0.12km
6.25%
0.30km
1.26%
0.40km
0.96%
0.50km
0.54%
0.60km
0.19%
0.70km
0.08%
0.80km
0.01%
It is calculated that the conditional probability of effective dose exceeding 10mSv is 1.26% at 300m, 0.54% at 500m, and only 0.01% at 800m. The plant boundary of CAP200 is 500m. Thus, according to the calculation results, the probability of the effective dose higher than 10mSv at 500m from the center of CAP200 reactor is far less than 30%. This indicates that for CAP200 SMR, its plume EPZ is limited to the site area and the off-site emergency response can be simplified accordingly.

27. 7.Prospect
Because the meteorological conditions at different sites have certain influence on the calculation of accident consequences, results of this paper only reflect the specific characteristics of the coastal site, and other sites still need to be analyzed according to the site characteristics.
Some other aspects have to be considered, such as public attitude, administrative divisions, terrain, etc.

28. 上海核工程研究设计院 www.snerdi.com.cn
谢 谢！
THANK YOU !
上海核工程研究设计院