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Re: TMI - the reality
I posted this earlier in the year, but as the topic of TMI is one of those
annual round robin events at Radsafe, I thought I would repost it. This
information was put together as a reality check for those involved in
emergency response who are tasked with plume/post-plume monitoring:
This is from a table that was put together for potential use in nuclear
power plant field team training during an emergency/release. It has long
been recognized that nuclear power plant drill scenarios often have to be
driven to what is commonly called the "blowing chunks" level to drive PAGs.
It was thought that a review of what response and dose assessment teams at
TMI saw would be of some use (and yes it is recognized that some of the
dose assessment data would not have been immediately known, but came from
after the fact assessments, and that there have been subsequent dose
assessments done after the cited reports were published). This of course is
part of the movement to bring back a little realism to drill scenarios.
Table VII. Keeping a Perspective: Summary of significant survey and
doseassessment data on and off site during the accident at Three Mile
Island for the period 28-Mar-79 to 4-16-79.
Description (a) and parameters
Highest ground reading onsite 3-28 2300
NW fence: 365 mR/h beta+gamma, 50 mR/h gamma
On 3-29 at 0500
WNW fence: 150 mR/h beta+gamma, 100 mR/h gamma
Highest reading during accident, helicopter 3-29 1410
15 ft over Unit 2 stack: 3000 mR/h beta+gamma, 400 mR/h gamma
Highest ground reading offsite, 3-29 0600
1 to 2 mile W: 30 mR/h beta+gamma, 20 mR/h gamma
3-28 DOE helicopter could detect plume out to 16 mi
0.1 to 0.2 mR/h
Highest offsite I-131 airborne concentration observed for period 3-28 to
4-12
32 picoCi/m^3 (3.2 × 10^-11 microCi/cm^3)
On 4-16, the highest immediate downwind I-131 concentrations were observed
during charcoal filter bank change-out operations
110 to 120 pCi/m^3 (max 1.2 × 10^-10 microCi/cm^3)
Occupational Doses
3 workers in excess of then 3 rem per quarter NRC limit (3.9 to 4.2 rem),
max 50 rem to skin and 150 rem to extremity
Max population dose estimate
3500 person-rem
Maximum estimated individual offsite whole body external dose
83 mrem
Maximum estimated internal doses to thyroid
Onsite: 53 mrem, adult
Offsite: 6.9 rem, newborn
Notes (b)
General emergency declared 3-28-79 at 0724. Initial dose projections 10
rem/h (Noble gas)to nearest community 1.4 miles away (5 rem evacuation
PAG), but field team measurements reported < 1 mR/h onsite at 0745 and at
nearest community at 0832. Offsite field team in nearest community did
report < 1 mR/h and I-131 near detection limits at 0900 and 3 mR/h at 1030.
Note that few dose rate measurements distinguished between open window
(beta+gamma) and closed window (gamma) instrument readings, or identified
the instruments used by the teams.
Initial air sample results using the Eberline SAM-2/RO-19 system (Dual
channel analyzer with NaI(Tl) scintillation detector, MDA ~5 x 10^-9
microCi/cm^3) indicated maximum onsite and offsite I-131 airborne
concentrations of 6.8 × 10^-7 microCi/cm^3 and 9.5 × 10^-7 microCi/cm^3,
respectively. Note that the present day 10CFR20 DAC for I-131 is 2.0 ×
10^-8 microCi/cm^3 (Table 2 value 2.0 × 10^-10 microCi/cm^3). Analysis by
GeLi reported I-131 less than MDA, but noble gases were identified.
Counting system could not detect I-131 in the presence of noble gases.
Initial dose projections grossly overestimated the actual dose rates
observed. The release was primarily noble gas with no significant levels of
radioiodine found offsite. No particulates were released.
Radionuclides released to the environment (From Table II-1):
Kr-88 (T_1/2 = 2.8 h) 3.75 × 10^5 Ci (15 % total), Xe-133 (T_1/2 = 5.2 d)
1.58 × 10^6 Ci (63 % total), Xe-133m (T_1/2 = 2.2 d) 2.25 × 10^5 Ci (9 %
total), Xe-135 (T_1/2 = 9.1 h) 3.0 × 105 Ci (12 % total), Xe-135m (T_1/2 =
15.3 min) 2.5 × 10^4 Ci (1 % total), I-131 (T_1/2 = 8.0 d) 1.5 × 10^1 Ci
(0.0006 % total)
(a) NUREG/CR-1250 1-80, Three Mile Island-A Report to the Commissioners and
to the Public, Vol. II, Part 2, Rogovin and Frampton U.S. NRC. Summary
descriptions found from page 384 to 400.
(b) NUREG /CR-1250 Vol. II, Part 3, p.344, 867 to 874 and 1037.
DJWhitfill
Opinions expressed are mine and do not reflect official policies or
positions of the Kansas Department of Health and Environment.
"Sandy Perle"
<sandyfl@EARTHLINK.NET> To: radsafe@list.vanderbilt.edu
Sent by: cc:
owner-radsafe@list.vand Subject: TMI - the reality
erbilt.edu
08/21/01 04:58 PM
Please respond to
"Sandy Perle"
Reality is:
Problem >>> Countermeasures >>> Results
>From the NEI website:
The Three Mile Island accident and its aftermath. The worst U.S.
nuclear power plant accident occurred at the Three Mile Island Unit 2
reactor near Harrisburg, Pa., on March 28, 1979. The accident was due
to a combination of equipment failure, inadequately designed
instrumentation, and the inability of plant operators to understand
the reactor's condition. Water from the reactor's cooling system
passed into the reactor building, but still within the containment.
The resulting heat that built up in the reactor's core melted the
metal of the fuel assemblies and the fuel pellets began to
disintegrate. Although a small amount of radiation was released, no
injuries, deaths or discernible direct health effects were caused,
according to over a dozen studies conducted between 1981 and 1991.
See especially the University of Pittsburgh Graduate School of Public
Health
{HYPERLINK "http://www.upmc.edu/newsbureau/gsph/three%5Fmile%5Fisland.
htm"}study, published in April 2000, covering the years 1979-1992 and
involving 32,135 individuals. Regulators and the industry diligently
studied the causes of the accident and developed improved safety
systems, operator training and supervision, and regulations that were
adopted industry-wide, resulting in a substantially safer nuclear
energy industry.
Institute of Nuclear Power Operations founded. In response to
recommendations by the Kemeny Commission, appointed by President
Carter to investigate the Three Mile Island Unit 2 accident, the
industry established the Institute of Nuclear Power Operations in
Oct. 1979. INPO sets performance objectives, criteria, and guidelines
industry-wide for overall nuclear plant operations, and conducts
regular evaluations of nuclear plants. INPO began monitoring
performance indicators in 1981 and formed the National Academy for
Nuclear Training in 1985 to accredit nuclear utilities' training
programs for plant operators and supervisors of operations.
Verifiable improvement after the Three Mile Island accident. In
response to INPO's report to the Commission in Mar. 1989, ten years
after the Three Mile Island Unit 2 accident, John Kemeny, chairman,
said: "The [industry's] improvements over the past decade have been
impressive and are very reassuring." One indication of the industry's
improvement is the subsequent performance of the remaining reactor at
Three Mile Island?Unit 1. In 1989 it achieved a capacity factor a
measure of reliability, efficiency, and safe operation?of 100.03
percent, the best in the world, and in 1999 it set the world's record
for the longest continuous run by a light water reactor, 688 days.
------------------------------------------------------------------------
Sandy Perle Tel:(714) 545-0100 / (800) 548-5100
Director, Technical Extension 2306
ICN Worldwide Dosimetry Service Fax:(714) 668-3149
ICN Pharmaceuticals, Inc. E-Mail: sandyfl@earthlink.net
ICN Plaza, 3300 Hyland Avenue E-Mail: sperle@icnpharm.com
Costa Mesa, CA 92626
Personal Website: http://www.geocities.com/scperle
ICN Worldwide Dosimetry Website: http://www.dosimetry.com
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