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TUESDAY, JULY 31, 1990
TWO GENERAL FORMS OF RISK ARE CONSIDERED INDIVIDUAL RISK AND SOCIETAL RISK. INDIVIDUAL RISK REFERS TO THE CHANCE, IN ANY ONE YEAR, THAT AN INDIVIDUAL WILL EXPERIENCE SOME SPECIFIED HARM WHILE SOCIETAL RISK IS ESSENTIALLY EXPRESSED IN TERMS OF THE PROBABILITY IN ANY ONE YEAR WITH WHICH SPECIFIC NUMBERS OF INDIVIDUALS, IN A PARTICULAR COMMUNITY, ARE HARMED.
THE REPORT SAYS THE RISK TO BE CONSIDERED AT DAYA BAY IS A MOST UNLIKELY SEQUENCE OF FAILURES OCCURRING AT THE SAME TIME WHICH COULD CAUSE THE REACTOR CORE OF A UNIT TO OVERHEAT. IF THAT HAPPENED AND WAS NOT STOPPED, SOME RADIOACTIVE MATERIAL COULD BE RELEASED INTO THE PRESSURE VESSEL AND FROM THERE POSSIBLY INTO THE CONTAINMENT BUILDING.
SHOULD THE CONTAINMENT FAIL THOUGH THIS HAS NEVER HAPPENED IN A PWR BEFORE RADIOACTIVE PARTICLES AND GASES WOULD BE RELEASED INTO THE ENVIRONMENT, WHERE THEY WOULD BE DISPERSED AND, VIA A NUMBER OF EXPOSURE PATHWAYS, COULD CAUSE HARMFUL EFFECTS TO HUMANS.
IN SUMMARIZING SOME OF THE IMPORTANT FEATURES OF THE CALCULATED RISKS, THE REPORT GIVES TWO EXAMPLES OF SOCIETAL RISK. THESE ARE :
THE PROBABILITY, PER YEAR OF STATION OPERATION, OF THE OCCURRENCE OF ONE OR MORE EARLY DEATHS IS ONE CHANCE IN A MILLION. LARGER NUMBERS OF EARLY DEATHS ARE LESS LIKELY.
THE PROBABILITY, PER YEAR OF STATION OPERATION, OF THE OCCURRENCE OF ONE OR MORE FATAL CANCERS IS ONE CHANCE IN 50,000. LARGER NUMBERS ARE AGAIN LESS LIKELY.
TWO EXAMPLES OF INDIVIDUAL RISK ARE GIVEN AND THESE ARE :
THE AVERAGE INDIVIDUAL RISK OF EARLY DEATH, PER YEAR OF STATION OPERATION, IS ONE IN 500 MILLION.
THE AVERAGE INDIVIDUAL RISK OF FATAL
STATION OPERATION, IS LESS THAN ONE IN
CANCER, PER YEAR OF
10 MILLION.
IN ASSESSING THE ABOVE RISKS, A NUMBER OF DELIBERATE PESSIMISTIC ASSUMPTIONS HAD BEEN MADE. THUS THEY ARE CONSIDERED TO BE OVERESTIMATES OF THE ACTUAL RISKS.
"THE ABOVE RISKS CAN BE PUT IN SOME PERSPECTIVE WITH OTHER RISKS TO WHICH INDIVIDUALS IN HONG KONG SUBJECTED, THE REPORT SAYS.
THEM
"IN
"
BY COMPARING ARE ALREADY
THE UNLIKELY EVENT OF A NUCLEAR ACCIDENT, EARLY DEATHS WOULD BE CLEARLY IDENTIFIABLE AS RESULTING FROM THE EVENT. THUS THE NATURAL COMPARISON IS WITH OTHER FORMS OF ACCIDENTAL DEATH.
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**FATAL CANCERS WOULD OCCUR RANDOMLY OVER A PERIOD OF ABOUT YEARS FOLLOWING AN ACCIDENT AND WOULD BE INDISTINGUISHABLE FROM NORMALLY OCCURRING CANCERS. THE NATURAL COMPARISON HERE, IS WITH THE NORMAL CANCER DEATH RATE.
THEREFORE,
/ESTIMATING THE