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Strengthen the Cooling Chain

in Passive Nuclear Power Plant

Shanghai Nuclear Engineering Research & Design Institute

Jun 22, 2015



Contents

1. Introduction of SNERDI

2. Strengthen the Cooling Chain

3. Summary

2



Founded in Feb 8th, 1970, originally belong to CNNC.

In 2007, became subsidiary of SNPTC.

Design of Qinshan NPP -- 1st NPP in China mainland.

Design of Pakistan Chashma NPP --1st China export NPP.

Technical support to imported CANDU-6.

Chinese CNP1000 development and design.

History


3



AP1000 technology transfer (TT), Assimilation and Absorption.

The standardization design and engineering of CAP1000.

The large passive PWR demonstration engineering, CAP1400.

Project achievement

4

Haiyang

CAP1400

Hongyanhe

Qinshan

Sanmen

Lufeng Pakistan

Operation

Construction

Bailong

Taohuajiang

Xianning

Pengze




Contents



3. Summary

5



6

2010 Conceptual design completed

2011 Basic design completed

2015 First concrete

2019 Connect to grid

Key Milestones of CAP1400




CAP1400 Main parameters

7

Parameters AP1000 CAP1400

Core thermal power, MWt 3400 4040

Electric power, MWe ~1250 ~1500

RCS average temp, ℃ 300.9 304

RCS pressure, MPa(a) 15.5 15.5

Fuel assemblies 157 193

Average linear power, W/cm 187 181

SG type △125 New design

SG outlet pressure, MPa(a) 5.61 6

Steam flow per loop, kg/s 944 1122

Design flow per pump, m3/h 17886 21642

DNBR margin >15% >15%




CDF: 4*10-7

LRF: 5.07*10-8

Enhancement against Fukushima Accident:

Design against extreme unlikely external events: flood, seismic,

Severe accident mitigation, Emergency response, Mass disturbances

event, Mobile pumps/diesel generators to further increase safety

margin…

Safety Review:

NNSA initiated the CAP1400 review in Apr, 2013 and last about 2

years, ~5000 questions answered, most of them closed.

One of the 19 critical questions is Strengthen the Cooling Chain.

CAP1400 Safety

8




The CAP1400 adopts passive safety systems to enhance plant

safety and to satisfy the 3rd generation NPP licensing requirements. The

passive safety are: PXS+PCS

CAP1400 Safety systems

9


PXS PCS



Independent electric power

To prevent the equipments backup of each other lost electric power at

the same time, we employ two independent electric source from different

bus.

Fire compartment

To prevent lost all the equipments by fire, we isolate the parallel

equipments by firewall，and the support system and electric power also

take the rule.

Raise seismic grade of SSCs related to Cooling chain

Design Criteria Raised for Cooling Chain

10




The scope of structure related to the cooling chain as followed:

Annex building (40)

Diesel Generator Building (60)

Circulating Water Pump House (71)

Turbine Building (20)

First Bay of Turbine Building (21)

Composite Trench (002)

Circulating Water Intake Ditch (023)

Cooling Chain related Structures

11




Seismic Design

Annex building :Designed per seismic category II and don’t need

strengthen.

Civil Standard：《Code for seismic design of buildings》

Diesel Generator Building :

Circulating Water Pump Houser Pump House

Turbine Building :

First Bay of Turbine Building

Circulating Water Intake Ditch

Composite Trench

Structure Strengthen Principle

12


The seismic response spectrum use the

spectrum of Site Safety Evaluation

（0.05g---→0.071g）

Meeting the demand and don’t need

change seismic design



Structure Horizontal Response spectrum

13


Horizontal

Period（S）

Acce

lera

tio

n R

esp

on

se

Sp

ectr

um

(g)



To prevent unnecessary actuation of the safety-related passive

systems and investment protection，it is necessary to strengthen the

Cooling Chain in Passive Nuclear Power Plant. The related systems are

as followed:

RNS: Normal Residual Heat Removal System

CCS: Component Cooling Water System

SWS: Service Water System

SFS: Spent Fuel Pool Cooling System

FWS: Main and Startup Feedwater System

DWS: Demineralized Water Transfer and Storage System

Cooling Chain related Systems(1/2)

14




And their supporting systems as followed:

ZOS: Onsite Standby Power System

ECS: Main AC Power System

EDS: Non Class 1E DC and UPS System

PLS：Plant Control System

DOS：Standby Diesel and Auxiliary Boiler Fuel Oil System

Cooling Chain related Systems (2/2)

15




Using the corresponding structure seismic response spectrum to

calculation and analysis the pipes, supports, anchors and equipments,

and horizon direction seismic force should be considered.

Purchasing mature CLASS C pumps and valves. If the supplies don’t

have mature CLASS C equipments, then they can supply the

equipment based on the response spectrum of Site Safety Evaluation

(Beyond 10% probability in 50 years)。

Update the related equipment specifications with these requirements。

System Strengthen Principle

16




The relationship between the cooling chain seismic strengthen

requirements and the existing seismic design of non seismic and investment

protection seismic：

Further requirements should be emphasized in the equipments specifications.

Emphasizes the availability of equipment under moderate earthquake

frequency.

Further development of cooling chain seismic strengthening acceleration

value accounting for the pipeline, support, anchor components.

Seismic Requirement Difference

17




18




The Electric and Instrument equipments of RNS should be designed

according to the 8 degree seismic level.

Cable tray should be designed in accordance with 7 degrees seismic

level evaluation (Annex building, diesel generator building are 8

degrees)。

Equipment classification maintain D level, seismic rating of non

seismic (NS), quality assurance level unchanged.

Seismic design is based on new floor response spectrum.

Further requirements should be emphasized in the specifications.

The Electric and Instrument Supporting System Strengthen Principle

19




Contents



3. Summary

20



To prevent unnecessary actuation of the safety-related passive

systems and investment protection，it is necessary to strengthen the

Cooling Chain in Passive Nuclear Power Plant.

During safety review，China National Nuclear Security Agency

(NNSA ) also put emphasis on cooling chain of Defence in Depth.

Strength the SSCs of the cooling chain and be approved by NNSA.

21

3. Summary



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Strengthen the Cooling Chain in Passive Nuclear Power Plant · PDF filesystems and investment protection，it is necessary to strengthen the Cooling Chain in ... Cooling Water System