Effect of Nuclear Reactor Accidents on Modern Nuclear Power Plant Design Eric P. Loewen, Ph.D. Past President American Nuclear Society

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1 Effect of Nuclear Reactor Accidents on Modern Nuclear Power Plant Design Eric P. Loewen, Ph.D. Past President American Nuclear Society April 22, 2013 United States Naval Academy

2 Who? Esquire Magazine, 2009

3 Why? ANS and professional societies Professional organization of engineers and scientists devoted to the applications of nuclear science and technology 11,500 members come from diverse technical backgrounds Dedicated to improving the lives of the world community within government, academia, research laboratories and private industry

4 What? Our Journey Together Today Incidents: Stationary Low Power Reactor One (SL-1) Three Mile Island Chernobyl Fukushima

5 Fission Energy: Fast and Slow Neutrons

6 6 Neutron Speeds

7 Challenging Times Station Land Reactor-One January 3, 1961

8 SL-1 United States Army experimental nuclear power reactor 3 MWt (200 kwe) January 3, 1961 underwent a steam explosion and meltdown Removal of single control rod caused reactor to go prompt critical Power jumped to 20 GW in 4 minutes

9 SL-1 Site

10 SL-1 Reactor Building Section

11 Top of Reactor Afterwards

12 SL-1 Reactor Perspective

13 SL-1 Take-Aways Design such that one control rod withdrawal will not bring reactor critical Operators are required to monitor the reactor plant New materials have been developed

14 SL-1 Take-Aways (Cont.) Cold shut down conditions can lead to higher control rod worth Prompt criticality can disperse fuel at high temperatures in the coolant and cause steam explosions

15 Movie Break SNL Metal/Water Experiments This movie has been donated to the City College of New York.

16 Binding Energy the New Fire Three Mile Island March 27, 1979

17 Fission Energy: Fast and Slow Neutrons

18 Pressurized Water Reactor

19 Simplified PWR Showing Three Mile Island Release Paths

20 TMI Lessons Learned Industry is only as strong as the weakest plant Institute of Nuclear Power Operation (INPO) started Plant simulator use increased

21 TMI Lessons Learned (Cont.) Conduct of plant operations formalized Degreed person required in control room Safety systems worked; no one was harmed U.S. nuclear power operations improved!

22 Controlling binding energy Chernobyl April 26, 1986

23 Chernobyl Nuclear Power Plants Population of Chernobyl was 49,000 Each unit is rated at about 3,200 MWth (four units) Direct-cycle, boilingwater, pressure-tube reactors. Steam is produced within the assembly

24 Fission Energy: Fast and Slow Neutrons

25 Chernobyl Plant Characteristics The reactor fuel rods (~1,700) are each contained in individual zircaloy pressure tubes embedded in a matrix of graphite blocks Each pressure tube contains 18 zircaloy-clad UO 2 fuel pins, enriched to 1.8% U-235 Reactor is 40 feet in diameter and 26 feet high On-line refueling at a rate of about one assembly/day

26 USSR RBMK 1000

27 Final Scenario 1:23:02 Test begins at reactor power of 200 MWth. 1:23:04 Power in the reactor increases (500 MWth) due to void buildup and pressure increases; eight reactor coolant pumps still operating. 1:23:31 Operator manually initiates reactor scram, but it is too late, since seconds are required for control rod insertion.

28 Seconds Later 1:23:40 Reactor is now on a high power, short period ramp, and reactor power reaches 110% normal (estimate). 1:23:43 Doppler feedback curtails first burst.

29 At the End 1:23:44 Second rector excursion to four times normal (estimate). (Fuel in channels, void complete, flow blocked.) 1:23:45 Pressure falls and reactor coolant pump flow returns to core; two audible/visible explosions observed.

30 Aftermath Reactor shield block destroyed and all 1,700 pressure tubes severed The audible explosions caused by a succession of events in sequence: Transient overpower reactor excursion Loss of flow Fuel-coolant interaction Hydrogen production Hydrogen combustion

31 Chernobyl Lessons Learned Worst design, operation and accident: 55 killed

32 Challenges from earth The Sendai Earthquake March 11, 2011

33 The Event The Fukushima nuclear facilities were damaged in a magnitude 9 earthquake on March 11 (2.46pm JST), centered offshore of Sendai region (Tokyo 250km SW). Plant design base was for magnitude 8.2 earthquake. The magnitude ~9 quake was greater in size. Serious secondary effects followed including a significantly large tsunami (> factor of 3), significant aftershocks and fires at/from many industrial facilities. Over 16,000 dead, 4,000 missing, 80,000 homeless limited resources - over 1000sq.km. land excluded 33

34 34 Accident Initiation

35 Six BWR units at the Fukushima Nuclear Station: Unit 1: 439 MWe BWR, 1971 (unit was in operation prior to event) Unit 2: 760 MWe BWR, 1974 (unit was in operation prior to event) Unit 3: 760 MWe BWR, 1976 (unit was in operation prior to event) Unit 4: 760 MWe BWR, 1978 (unit was in outage prior to event) Unit 5: 760 MWe BWR, 1978 (unit was in outage prior to event) Unit 6: 1067 MWe BWR, 1979 (unit was in outage prior to event) Unit 1 35

36 36 Fukushima Accident Initiation

37 Overview of Boiling Water Reactor Typical BWR/3 and BWR/4 Reactor Design Similarities to BWR/4 Plants in Midwestern US 37

38 Major Design Parameters for Fukushima Dai-ichi Units 1-4 Unit 1 Unit 2 Unit 3 Unit 4 Commercial operation Reactor design BWR-3 BWR-4 BWR-4 BWR-4 Rated power (MWe) Thermal power (MWt) 1,380 2,381 2,381 2,381 Isolation cooling system IC RCIC RCIC RCIC ECCS configuration HPCI (1) ADS CS (4) HPCI (1) ADS CS (2) LPCI (2) HPCI (1) ADS CS (2) LPCI (2) HPCI (1) ADS CS (2) LPCI (2) Primary containment vessel Mark-I Mark-I Mark-I Mark-I Operation status at the earthquake occurred In service Shutdown In service Shutdown In service Shutdown ECCS: Emergency core cooling system, HPCI: High pressure core injection system, ADS: Automatic depressurization system, CS: Core spray system, LPCI: Low pressure core injection system, IC: Isolation condenser, RCIC: Reactor core isolation cooling system Outage

39 Earthquake at 14:46: LOSP Tsunami at 15:41: SBO IC operating level loss Accident Sequence Summary Timeline of Major Fukushima Damage Sequences Unit 1 SC Saturated core damage Sea water injection Containment vent H2 Explosion RCS Repressurizes RCS Depressurized Unit 3 RCIC operating HPCI operating Level loss SC Saturated RPV Depressurization Sea water injection? Core damage? Sea water injection Containment vents H2 Explosion Unit 2 RCIC - CST RCIC from suppression pool SC Saturated Level loss RPV Depressurization Sea water injection Fuel damage Containment vent Noise from torus room Unit 4 (SFP) Explosion in Unit 4 Friday 11 Saturday 12 Sunday 13 Monday 14 Tuesday 15 Wednesday 16 Information 39 within this illustration was developed from the INPO Special Report and the Report of Japanese Government to IAEA Ministerial Conference on Nuclear Safety Accident at TEPCO s Fukushima Nuclear Power Stations Transmitted by Permanent Mission of Japan to IAEA, June 7, 2011

40 Loss of four generation units No loss of human life The earth is a dangerous place to live

41 Other Energy Accidents

42 Other Energy Accidents: Gas A natural gas pipeline exploded, setting off a blaze that destroyed a San Bruno, California neighborhood, killing eight people and wrecking 37 homes. Photo courtesy of Dan Honda/Zuma Press

43 Other Energy Accidents: Coal Twenty-nine miners died after an explosion at the Pike River coal mine in New Zealand on November 19. Photo: Xinhua/Zumapress.com

44 Other Energy Accidents: Wind Windmill on fire in Palm Springs, California. Photo courtesy of Metacafe.com.

45 Other Energy Accidents: Oil Off shore oil rig explosion off the Louisiana coast takes 11 lives. Photo courtesy of UPI.

46 Other Energy Accidents: Hydro Sayano Shushenskaya hydroelectric power station accident in Russia take 76 lives. Photo courtesy of the Daily Mail.

47 What Now?

48 Join ANS!

49 Thank You! For more information contact the ANS Public Outreach department at or visit ww.ans.org.

50 The American Nuclear Society