3 Levy STRATEGY AND ACTIONS TO ASSURE BWR ......INPO PUBLISHES MANY VALUABLE DOCUMENTS AND...
Transcript of 3 Levy STRATEGY AND ACTIONS TO ASSURE BWR ......INPO PUBLISHES MANY VALUABLE DOCUMENTS AND...
STRATEGY AND ACTIONS TO ASSURE BWR
SAFETY DURING STATION BLACKOUT (SBO)
By
Dr. Salomon Levy, Honorary Member ASME
SL1‐10/25/11
SCOPE OF PRESENTATION
PART ONE: COMPARE USA NRC AND JAPAN
REGULATIONS AND GUIDANCE DURING SBO AND SEVERE
ACCIDENTS.
PART TWO: COMPARE USA AND JAPAN OPERATIONS
MANAGEMENT AND TRAINING.
PART THREE: STRATEGY AND ACTION ITEMS TO ASSURE
BWR SAFETY DURING SBO
USA AND JAPAN PROVISIONS FOR NATURAL
PHENOMENA
Natural phenomena are earthquakes, tsunamis, winds,
and floods.
USA NRC requires that all safety structures, systems, and
components be designed for “even rare and extreme
events”.
In Japan many parties involved with potential conflict of
interest: NISA, NSC, MITI, Japan Society of Civil Engineers.
Fukushima Daiichi Design Basis Height set at +5.7 meters.
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SL3‐10/25/11
NATURAL PHENOMENA (CONTINUED)
Appropriate probabilistic model would yield tsunami
heights >> 5.7meters.
Urgent action and plant changes needed.
Hamoaka proposing 18 meters tsunami height to restart
plant.
USA BWRs would have fared much better due to not
being subject to tsunami (Nuclear Eng. International,
Nov.2011).
Due to serious flooding at Fukushima Daiichi of
emergency systems and diesels, Japan flooding
regulation may deserve additional review.
SL4‐10/25/11
OTHER DIFFERENCES IN USA AND JAPAN REQUIREMENTS
NRC REQUIRES SBO ASSESSMENT AND STRATEGY. JAPAN SHOULD HAVE
USA FULLY RELIES UPON RISK ASSESSMENT AND UPON PRAs/PSAs.
JAPAN NEEDS TO INCREASE
USA FULL COMAND AND CONTROL AT SITES DURING SBO. JAPAN
REQUIRES ADDITIONAL APPROVALS
WHICH DELAY CRITICAL DECISIONS
CONTAINMENT VENTING STRATEGY LEFT UP USA BWR SITES. JAPAN
REQUIREMENT DOES NOT ALLOW VENTING UNTIL CONTAINMENT
PRESSURE EXCEEDS DESIGN PRESSURE AND ON ITS WAY TO TWICE
DESIGN PRESSURE. RESULT IS RATHER HIGH HYDROGEN
CONTENTWHICH ENSURES EXPLOSIONS
SOME ELEMENTS OF NRC PROGRAM FOR 9/21/2001 COULD BE USEFUL
IN JAPAN SUCH AS THOSE FOR SPENT FUEL POOLS
SL5‐10/25/11
USA AND JAPAN OPERATIONS MANAGEMENT AND TRAINING
SIGNIFICANT DIFFERENCE BETWEEN USA AND JAPAN DUE TO USA INPO
INPO FORMED BY USA NUCLEAR POWER PLANT OWNERS AFTER TMI‐2
ACCIDENT
INPO REVIEWS PLANTS, GIVES RATINGS TO PLANTS, MAKES
RECOMMENDATIONS AND FOLOWS UP ON THEM, AND APPROVES
OPERATIONS TRAINING PROGRAMS
INPO PUBLISHES MANY VALUABLE DOCUMENTS AND COMMUNICATES
SIGNIFICANT EVENTS AND CORRECTION TO ALL PLANTS
INPO REPORTS TO PRESIDENTS IN ORDER TO ASSURE IN ORDER TO
ACHIEVE TOP NUCLEAR SAFETY CULTURE
AWARE OF WANO WHICH HAS CONSIDERABLE LESS INFLUENCE
STRONGLY RECOMMEND JAPAN INPO
SL6‐10/23/2011
WHY JINPO
TO IMPROVE JAPAN OPERATIONS AND PHYSICAL
UNDERSTANDING AND SAFETY OF PLANT EQUIPMENT
TYPICAL EXAMPLES FOR JAPAN IMPROVEMENTS AT
UNIT1:
JAPAN HAS MAAP AND MELCOR TO PREDICT URGENCY
OF ADDING WATER DURING SBO BUT PERSONNEL NOT
WELL VERSED IN THAT NEED.
ACTIONS AFTER SBO SUBJECT TO QUESTION, SUCH AS SHUTOFF OF IC AND INITIATION OF HPCI AS WELL AS
TEMPERING WITH IC BY USING IT TO CONTROL
PRESSURE.
OVER RELYING UPON WATER LEVEL WHEN ITS
ACCURACY IN DOUBT
REPORTED ABILITY TO DEPRESSURIZE AND ADD WATER
AT 17:30 PM ON 3/11. WHY NOT CARRIED OUT?
It is most unfortunate that data were not available after
tsunami because strategy would have been improved with
data.
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.,
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RECOMMENDED STRATEGY AND ACTION ITEMS
Strategy not changed. It consists of assuring IC and RCIC
are operating satisfactorily, having external source of
water to reactor as soon as possible and to take reactor
to cold shutdown as soon as possible. Action items are:
Fix tsunami model and make necessary physical
changes.
Have SPDS available during SBO. Assure IC and RCIC are operating Be ready with external source to add water to reactor and use when available
Move heat sink beyond reactor/containment by
providing exit from reactor
Carryout actual tests simulating SBO in actual BWR
after a normal shutdown with shutdown and
emergency cooling systems on standby. Tests to be
fully reviewed and approved. Test purpose is to
find out leakage during IC operation at full
pressure and RCIC degradation with increased S/C
containment water temperature and battery
approaching end of life.
Test results to be incorporated in plant simulators
and use simulators for future periodic training of
BWR personnel.
SL7&8‐10/25/11