Read PowerPoint Template White Background Class 3 text version

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

AP1000® Safety Concepts and Robustness to External Hazards Proceedings of SIEN 2011 Bucharest, Romania October 18, 2011

Andrew Pfister

AP1000® is a registered trademark in the United States of Westinghouse Electric Company LLC, its subsidiaries and/or its affiliates. This mark may also be used and/or registered in other countries throughout the world. All rights reserved. Unauthorized use is strictly prohibited. Other names may be trademarks of their respective owners. 1

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

2

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

AP1000 Approach to Safety

· Passive Safety-Related Systems

­ Use "passive" processes only, no active pumps, diesels, .... ­ One time alignment of valves, fail safe for SBO ­ No support systems required after actuation ­ Greatly reduced dependency on operator actions ­ Mitigate design basis accidents without active systems ­ Meet NRC PRA safety goals without credit for active systems

· Active Defense in Depth-Related Systems

­ Reliably support normal operation ­ Redundant equipment powered by onsite diesels ­ Minimize challenges to passive safety systems ­ Not required to mitigate design basis accidents

3

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

AP1000 Passive Core Cooling System Eliminate the need for AC Power

Passive Residual Heat Removal (PRHR HX)

­ Natural circ. heat removal replaces auxiliary feedwater pumps

Passive Safety Injection

­ Core Makeup Tanks (CMT) ­ Full RCS pres, natural circ. inject (replaces high head injection pumps) ­ Accumulators (ACC) ­ Similar to current plants ­ In-containment Refueling Water Storage Tank (IRWST) Injection ­ Low pres (replaces low head injection pumps) ­ Containment Recirculation ­ Gravity recirc. (replaces pumped recirc) ­ Automatic RCS Depressurization ­ Staged, controlled depressurization

4

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Passive Containment Cooling System

· Simple, "fail safe", water drain actuates system

· Decay heat is transferred to air and PCS water through the steel containment vessel.

IRWST PRHR HX

· No recirc of water CMT outside containment · Maintains containment integrity with no actions or power required.

Accumulator

· No radiation releases.

5

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Major Safety Advancements of AP1000

·

No Reliance on AC Power; Long Term Plant Safety Assured without Active Components (Natural Forces Only)

­

­

For Station Blackout (SBO), AP1000 meets aggressive 72 hours coping time requirements for passive plants using fail safe components ­ Active plants SBO coping period requirement is 8 hours or less Significant risk reduction for loss of power events: ­ For advanced active plants design, LOOP / SBO events are a dominant contributor to the Core Damage Frequency (> 25%) ­ AP1000 CDF contribution for loss of Offsite Power / SBO is 0.4%

· · · ·

No Operator Action Required to Assure Safety Large Margin to Safety Limits Defense in Depth - Active Systems Provide ADDITIONAL first line of defense In Severe Accidents, Reactor Vessel Cooling Keeps Core in Vessel

6

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Initiation of Natural Circulation & Decay Heat Removal

0 ­ 72 hours

· SBO results in reactor trip · Remove decay heat · Passive core cooling · Passive containment cooling

3 ­ 7 days

· Start Ancillary Diesel Generators · Provide power for control room lighting, instrumentation for plant operators, and Passive Containment Cooling Recirculation Pumps · Passive Containment Cooling Ancillary Water Storage Tank

7 days & beyond

· Additional sources of makeup water available onsite to continue operation of Containment Cooling indefinitely · External water sources (tanker trucks, emergency vehicles) can be used to transport fresh water

7

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Mid-Term Reactor Decay Heat Removal 3 - 7 Days

·Ancillary Diesels provide AC power for post-72 hour operations. ·Ancillary Water Storage Tank provides water for containment cooling and the SF pool makeup for up for 4 additional days. ·PCS recirculation pumps, powered by ancillary diesels, provide water to the spent fuel pool and the containment outer surface.

Ancillary Diesels Ancillary Water Storage Tank PCS Recirculation Pumps

8

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Long-Term Cooling Post Shutdown (7 days and beyond)

Fire Protection Tanks Condensate Storage Tank

·Permanently installed connections for off-site support hook-up, both AC Power and Water, are in place.

Service Water CT Basin

·With minimal operator actions core cooling, containment cooling, and spent fuel cooling are maintained indefinitely.

·Post 7 day features may be used earlier if needed.

Boric Acid & Demineralized Water Tanks

9

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Spent Fuel Pool Cooling and Makeup

0 ­ 72 hours

· Loss of all AC power · Boiling occurs · Makeup water provided to maintain level above assemblies · Building relief panel opens automatically

3 ­ 7 days

7 days & beyond

· Alternative sources of water supply may be used, e.g., Fire Water Tanks and Demineralized Water Storage Tanks · Site-specific, temporary equipment will be used to transfer water from alternative sources

· One of two PCS Recirculation Pumps (powered by the Ancillary Diesel Generators) pumps water from Ancillary Tank

10

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Coping Comparisons AP1000 PWR far exceeds NRC minimum

NRC Requirement

4

Existing US Plants

4-8

AP1000

168 (7 days)

0 25 50 75 Hours 100 125 150 175

11

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Comparison of Contribution of SBO to Core Damage Frequency (CDF)

0.4%

AP1000

25%*

AP1000 NPP

Existing Plants

*Average value

12

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

AP1000 Design for External Hazards Seismic Hazards

· Safe shutdown earthquake (SSE) of 0.3g is the basis for the seismic design of Seismic Category I & II structures

· Design exceeds EUR requirement of 0.25 g · Site conditions are likely to result in additional seismic margin · Seismic Category II structures prevents adverse interaction with structures important to safety · Non Nuclear Seismic (NNS) structures are designed for industrial seismic requirements · Seismic margin assessments demonstrate that critical SSCs have a high confidence of a low probability of failure (HCLPF) for a seismic event up to the Review Level Earthquake of 0.5 g (1.67 times SSE)

13

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Flooding

Design Basis Flooding · AP1000 design requirements specify that site grade, plant elevation 100'0", be above the maximum probable flood limits · Flooding that does not exceed site grade elevation would not affect safe shutdown components External Flooding Margin · In an extreme event where the site suffers a severe flood which greatly exceeds the basis, the reactor core and Spent Fuel Pool remain protected · Containment would remain unaffected · Fail-safe nature of most critical safety functions will automatically actuate passive systems required for decay heat removal and containment cooling with a postulated loss of all AC and DC power

14

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Malicious Aircraft Impact

· AP1000 is designed to protect

against both military and large commercial aircraft impacts

­ Evaluations complete for both the US and Europe

­ Assessments demonstrate that the Shield Building prevents containment damage

­ Assessments consider the effect of structural damage, shock and vibration, and large fires

· Assessments have been

extensively reviewed by US NRC, UK ONR, & independent industry peer review committee

15

Westinghouse Non-Proprietary Class 3

© 2011 Westinghouse Electric Company LLC. All Rights Reserved.

Conclusions

· The AP1000 nuclear power plant is less vulnerable to

extreme hazards because:

­ AP1000 "fails safe." Even with a loss of all electrical power, I&C controls, and instrument air, for most circumstances the AP1000 passively aligns crucial safety related systems to a safe state which protects the reactor core and the spent fuel pool. ­ AP1000 is self-reliant. The AP1000 passive approach reduces the importance to plant safety for AC electrical power or heat sinks such as the service water cooling interface with nearby bodies of water. AP1000 plants ultimately use ambient air as a heat sink. ­ AP1000 is self-contained. Any structure, system, or component required to place the AP1000 into a safe shutdown is located within the steel containment vessel and surrounded by the robust steelconcrete-steel Shield Building.

16

Information

PowerPoint Template White Background Class 3

16 pages

Report File (DMCA)

Our content is added by our users. We aim to remove reported files within 1 working day. Please use this link to notify us:

Report this file as copyright or inappropriate

449243