ML19199A353
| ML19199A353 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/12/1979 |
| From: | Rehm T NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | NRC COMMISSION (OCM) |
| Shared Package | |
| ML19199A354 | List: |
| References | |
| NUDOCS 7904170015 | |
| Download: ML19199A353 (93) | |
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APR 1 2 1979 Directors of Offices The attached information on Three Mile Island is provided for your information because of V
current interest in the matter.
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Chairman's Testimony of 4/10/79 i
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Chronology of NRC Actions (preliminary) i J.
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Description of Events at TMI-2 Facility
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Accident (preliminary) p:.
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Generic Considerations of TMI-2 Incident t
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Summary of Initial Response & Radiological E
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Summary of Radioactive Licuid Release f
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Preliminary Evaluation of Health Effects T-of the TMI Incident 5
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Resident Inspection Program I
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Population Dose Estimates - Update of i=;~
April 1 NRC/ HEW / EPA study
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TESTIMONY OF CHAIRMAN HENDRIE BEFORE THE SUBCCMMITTEE ON NUCLEAR REGULATION OF THE SENATE CCPNITTEE ON ENVIRONMENT AND PUBLIC 'ACRKS TUESDAY, APRIL-10, 1979 Mr. Chairman, as you and I agreed in arranging this hearing, we are here to present a preliminary account of what happened at Three Mile Island, our response to the accident, and some initial conclusions in order to put these matters on record at an early time.
I am very grate #ul for and appreciative of your understanding that we could not and shculd not divert any appreciable staff resources from the operations at Three Mile Island or from the support groups at Ee:hesda to prepare a more extensive record for this hearing.
There will, of course, be more detailed investi-gations, and we will look forward to future hearings in which a further accounting can be made.
Fir:t, by way of general comment, I want to emphasize my great personai ccncern, which I know is shared by my colleagues on the Ccmmission and all members of our staff, that this accident at Three Mile Island Unit 2 has happened. All of us are profoundlyj gagk{ul, as I am sure you and all of our citi: ens are, that the radiation exposure levels to the public in the area of Three Mile Island have been lcw.
Hcwever, we do not take much comfort frcm the low radiation exposures experienced to cate since it is clear that the potential for substantially larger exposures of the puolic existed during the course of this accident.
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A us t-d ENCLOSURE 1 C-
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2 The efforts of a very large number of people in the license 2's organiza-tion, the&r anwa,lHetsta or Pennsylvania, the NRC, other Federal and State egencies, and industry groups.are being applied to make sure that we can collectively maintain and improve the conditions that have prevailed thus far witn regard to the offsite public and the workers at tne site.
The rapid marshalling of-very extensive resources frcm a wide variety of sources has been a heartening experience and I believe the record should include an expressicn of our appreciaticn to the hundreds of individuals anc organizaticns that have responded.
bcW It is my view, and I aT. 2.Te it is yours as well, that we cannot have an acceptable nuclear power program in this country if there is any appre-ciable risk of events of the Three Mile Island kind occurring at nuclear power plants.
The Nuclear Regulatory Commission must prcmptly carry out a searching review and evaluation of our own policies and procedures, in addition to our q"estigation of what has taken place at the Three Mile Island facili ty.
We must find out where our inspecticn and enforce-ment of safety-related operating requirements, our design standards, and our reviews of possible transient and accident situations have somehow been inadequate to prevent the Three Mile Island accident.
We already have put those elements of the staff that are not immediately involved in dealing with the situaticn at Three Mile Island to work on this essential and major effort.
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e The Nuclear Regulatory Commission's investigation of the Three Mile Island accident is actively underway.
Of course, our most immediate concern nas been dominated by the operational considerations of limiting further releases and returning the plant to a safe and secure shutdown condition.
Consistent with our efforts in that direction and to the extent we could do so without interfering with the-recovery operation, our investigators have been at work gathering informaticn.
The NRC investigatien team is new at the Three Mile Island site in the field phase of its work, following several days of review of plaat records and charts furnished to our Operations Center in Bethesda.
As you are aware, Mr. Chairman, the NRC deliberated very carefully concerning the possibility of serious generic concerns that might require shutcown of the other nuclear power plants designed by Babcock and Wilcox, the nuclear steam system supplier for the Three Mi n island plant.
The results of our review in this area led us to the conclusion that although 5 utdowns were not warranted at other S&W plants, it was important to recuire these other utilities to make changes in operating procedures and to carry out supplementary training of their operators.
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These required actions were taken prcmptly and are being folicwed up by increased inspection activities.
First, an NRC Inspection and Enforcement Sulietin was transmitted on April 1, directing licensees operating S&W reactors to perform a series of specific reviews and actions.
The licensees must respond by tcmorrow.
Our onsite inspectors will monitor compliance with this Bulletic.
The NRC Headquarters staff will review the responses prcmptly and act upon them accordingly.
This Bulletin was supplemented by another on April 5 that provided additional specific operating instructions based on our augmented understanding of the events at Three Mile Island.
(Copies of these Bulletins are attached for the record.)
Second, an inspector was assigned full-time at each operating plant having a B&W reactor by April 2.
In addition t' assuring that the Sulletins are fully understood and folicwed, the full-time inspector --
with additional assistance frcm the NRC Regional Offices -- will assure that scme inspection activities will occur during sach shift and tnat each shif t will have a clear understanding of the guidance.
Regional and Headquarters staffs are staying in close touch with the onsite NRC inspectors to be sure that our instructicns to the licensees are being carried out.
Furthermore, the Commission has sent a telegram to eacn of the licensees with B&W reactors to underscore the seriousness with which tne Commission views this situation. (A copy is attacned for the record.)
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Inta. ally, an NRC Task Force on Generic Review of Feedwater Transients in B&W Reactors has been formed to examine the reactor and plant systems at tnese plants that provided protection against feecwater transients.
The Task Force 'eport is expected to be completed before the end of this month. We will carefully review that information and take whatever further action may be appropriate.
Pending completion of our review of the responses to the April 1 Bulletin and in view of the actions which the NRC has taken and our currant understanding that operator errors played an important role in the accident, we believe there is reasonable assurance that the plants can continue to operate without danger to the public health and safety.
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specific procedures are prudent and provide a considerably enhanced ye/d4P j
r level of assurance, he would await the report of this Task Force before sharing fully in this ccnclusion.
Before cescribing the situation at Three Mile Island, I should like to comment on President Carter's role.
From the outset we have kept the president fully informed concerning the accident.
He has been most nelpful in provicing us witn his personal views and suggestions and in making availabla to the NRC a communications network.
Moreover, his visit to the site on Acril I helped alleviate tne ' rowing anxiety of the people in the area.
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In his recent energy address, the President expressed 00ncern about the accident and cirected that an indepencent Presidential Ccmmission be established to investigate the causes of the accident and to make recommendations en hcw the safety of nuclear power plants can be improved.
The Nuclear Regulatory Commission will, of course, ccocerate fully witn the Presidential Commission in every way.
Initial Events At about 4:00a.m. on March 23, 1979, an event occurred which !ead to the accident at the Three Mile Island Unit No. 2 facility.
The secuence of events included a loss of feedwater flow, the sticking open of a primary relief valve, the premature turning off of the emergency core cooling system, 3nd later the turning off of all reactor ccolant pumps.
Shortly before 7:00a.m. a site emergency was declared by the utility as it became apparent that the reactor fuel had been damaged.
I would now like to have Mr. Darrell Eisenhut go through the detailed sequence of events, as we understand them new, in the first hours of the accident. Then I will resume my statement.
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At about 7:00 a.m. en March 28th, the licensee notifiec the State of Pennsylvania.
At 7:45 a.m., the licensee reached the NRC Region I office, and within h hour the NRC Incident Response Center in Bethesda was operating.
The '!hite House was alerted at 9:15 a.m., and by
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10:05 a.m. the first NRC Response Team was en the, site, a group of five inspectors frcm our Region I office.
At 10:15 a.m. the Cemnissian was oriefed by the Director of the Office of Inspection and Enforcement.
NRC had 11 people and a mobile laboratory van frcm the Region I Office on site by evening; radiological assistance teams frca 3rcokhaven Laboratory were monitoring the site vicinity frcm mid-afternoon on.
An Aerial m L m K.s % X q Ri% b Monitoring Survey aircraft also was at the site by mid-afternocn.
NRC strength at the site increased to 29 on Thursday and 83 en Friday.
(A brief chronology of these response actions is attached for the record.
From Wednesday on, there were continuing releases of radioactive gas evolving frem the reactor cooling water which had been pumped from the containment building to the auxiliary building.
Despite efforts to halt these releases, they increaseo on Friday morning.
This situation led to a decision by Governor Thornburgh -- en the Ccamission's reccmmendation --
to advise preschool children and pregnant semen to leave the 5-mile zone nearest the reactor.
The releases were greatly reduced on Friday afternocn when some of tre water in the auxiliary building was pumped to storage tanks emptied for that purpcsc.
NPC increased the level of its ensite team, and Harold Denten, the Director of Nuclear Reactor R gulation, was 13 3.r8
t w LW placedinchargeb'Ccmmunications and transpcrtation support were supplied at White House direction.
Other Federal agencies provided additional assistance.
NRC received the full cooperation of Pennsylvania State government officials as well as other Federal agencies.
Ncwhere was this cooperaticn more apparent than in the vi+. ally important area of radiological monitoring.
For instance, the Cepartment of Energy's Aerial Monitoring Survey airplane was on station over the site within a few hours.
Personnel frcm the Pennsylvania State Bureau of Radiological Health were making measurements from Thursday afterncen onward.
Radiological monitoring efforts were also carried out by HEW and EPA teams.
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Cn Friday, it was recognized that the early core damageA ad fomed a h
b' substantial quantity of hydrogen gas, some of which was thought to have collected in the reactor pressure vessel above the core.
One concern was that if the reactor pressure was decreased, the hydrogen bubble would grow and might interfere with the flow of cooling water througn toe core.
Another was that oxygen generated by radiolysis of water might accumulate -- with the potential fur forming a flamable mixture.
The Comission consider 2d reccmending additional evacuation measures beycnd those previously recommended to Governor Thornburgh -- which I indicated in my press conference on Saturday afternoon -- but deciced that 13 :?"9
.g-increased protective action was not necessary.
I should note that at f wvl6 pm >
cne time or another frca Friday morning through Sunday,jmembers of the senior staff and varicus Commissicners cre;;csed either stronger advisories or actual evacuation of people within a two or five mile circle around
.h 4b V M Three Mile Island.
However, the estimates fecm-W staff at the site remained considerably more optimistic than those which cculd be based on W he the more limited information available tM: '1Wdsh4.n.
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Consequently, stronger recommandations were not made to Governor Thcrnburg.
The precise timing and content of the varicus proposed Ccmmission reccmmendations will certainly be made public as scan as all of the relevant tapes and notes can be reviewed and transcribed.
The information will then be prcmptly. furnished to the Congress.
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/ yod By S;nday, A?ril 1, it appeared that efforts to underst$nd and manage the hydrogen bubbl_e were meeting with scme success.
Over the folicwing few days, the bubble was reduced to negligible size by degassing with the pressurizer spray and the letdcwn ficw and by gas dissolving in the reactor coolant water.
Further analysis had also indicated that little, if any, oxygen could be evolved in the hydrogen-rich conditions of the reactor system. Thus, the period of immediate crisis passed and the reactor cooldewn process could proceed witheyt the hydrogen bubble problem.
The entire recovery operation is being conducted in a way that minimizes the release of radicactivity from the site ar.d that requires very.areful 1G
'30 consideration and concurrence by the on-site hRC team in every significant action taken. With the reactor in a stable cooling status since early in the accident, we have been very cautious about moving too rapidly in the recovery operations lest we encounter situations that have not been carefully thought out.
I am convinced that this is the correct approach, even though, from the public's point of view, it may seem to prolong the emergency.
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Let me new give you a brief status report _oD the
.rrent situation at Three Mile Island.
I was at the si, egain last Sunday and have been in close contact with Harold Denton and his team at tne site throughout the accident.
Conclusion The staff has identified six main factors that caused and increased the severity of the accident.
Thesa are as follows:
1.
At the time of the initiating event, loss of feedwater, both of the auxiliary feedwater trains were valved out of service. This was a violation of the plant Technical Scecifications.
2.
The pressurizer electr:matic relief valve, which opened during the initial pressure surge, failed to close when the pressure decreased belcw the actuation level.
This failure was not recogni:ed and the relTer line closed for seme time.
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Folicwina rapid depressurization of the pressuri:er, the pressuri:er level indication may have lead to errcneous inferences cf high it/ei in the reactor coolaat system.
The pressurizer level indication apparently led tne operators to prematurely terminate high pressure injection ficw, even :nough substantial voids existed in the reacter coolant system.
4 Because the containment does not isolate on high pre:sure injection (HPI) initiation, the highly radioactive water frca the relief valve discharge was pumoed out of the containment by the autcmatic initiation of a transfer pump.
This water entered the radioactive waste treatment system in the auxiliary building where scme of it everficwed to the ficor.
Outgassing frcm this water and discharge thr ugh the auxiliary building ventilation system and filters was the principal source of the offsite release of radicactive ncble gases.
5.
Subsequently, the high pressure injection system was only intermitten:ly operated to control primary ccolant inventory losses through the electrcmatic relief valve, apparently based on pressurizer level indication.
Due to the presence of steam and/or noncondensible voids-cisewhere in the reactor c0olant system, this led to a further reduction in primary coolant inventory.
5.
Tripping of reactor coolant pumps during the course of the transient, presumably to protect agairst pump damage due to pump vibratica, led to fuel damage since voids in the reactor coolant system prevented natural circulation.
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. As I remarked at the beginning, ! am geeply concerned about the accicent at Three Mile Island and its implicaticns.
Even though, as far as we can determine at this time, no one was exposed to dangerous radiation levels, the accident was inceed serio.
The lives of the people in the neighboring c:mmunities were disrupted and many individuals experienced personal hardships.
And, of course, the acencmic consecuences of the accident are sucstantial.
We cannot tolerate accidents of this kind and we must take whatever steps are necessary to prevent them.
We have a lot to learn from the Three Mile Island accident.
I would like to emphasi:e here that I'm not just thinking of improved harcware or procedures, or other technical fixes.
I'm thinking of the regulatory framework itself.
I do not see the Three Mile Island accident and its implications as matters that can be addressed exclusively en a technf:al plane.
For example, the total response of all parties involved reveals that a critical reexamination of the relationship among licensees, regulators and support groups during crisis management is needed.
I do not mean to convey any imoression of conflict among these groups arising out of the Three Mile Island accidelt.
Indeed, cJoperation has been very good.
However, during these last 2 weeks we in NRC have been heavily involved Il?b I? ]C) in operational matters that we nemally ex;ect to be primarily the licensee's responsibility, subject to our review and approval.
Our involvement in these matters has been appropriate under the circumstances, but we believe that we new should lock more carefully at our preplanned role in crises.
It is persible that legislative acticn may be needed in this area.
We have been sorely taxed to assemole NRC personne! frcm our other Regional Offices and our licensing offices to provide onsite NRC staff support. We may find that cur budget planning has inadequately considered the impact of short-term heavy demands such as the Three Mile Island accident.
It is already clear to me that among the likely areas where imorovements snculd be made are first, a substantial upgrading of reactor ocerator training with respect to plant transients and off-normal conditions.
Second, we should put more emphasis in our staff reviews and safety regulations on safety measures to deal with plant transients originating in the secondary or steam-producing side of nuclear cower plants.
Third, we must carefully reexamine tne sensitivity of all plant designs to these transient situations and we must reexamine the automatic safety systems :".at deal with them.
Finally, we must make certain that our licensing review and our inspection procedures are as cacaole as we can make them of preventing the mistakes that were made at Three Mile Island.
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5 oje Sulletin and enclosures should also be dispatched for inforcation all po'cler react 0r ConstructiCn 'ermit holders.
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Enclosures :
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Draft Transmittal Letters to C 2 Licensees 2.
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_nis in c i Description of Circumstances:
On March 28, 1979 the Three Mile Island' Muclear Pcwer Plant, Unit 2 experienced core damaga which resulted frca a series of events which were initiated by a loss of feedwater transient.
Several aspects of the incident may have general applicability in additica to apparent generic applicability at cperating Sabcock and Wilccx reactors.
This bulletin is provided to inform you of the nuclear incident and to request certain cctions.
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For cil Babcock and Hilcox pressurized water reactcr facilities with an operating 1icense:
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Review the descriptica (Enclosure 1) of the initiating events and subsequent course of the incident.
Also review the evaluation by the MRC staff of a postulated severe-feedwater transient related to Babcock and Wilcox PWRs as descri' ed in Enclosura 2.
c These reviews should be directed at assessing the adequacy of your reactor systems to safely sustain cooldown transients such as these.
2.
P.eview any transier.ts of a similar nature which have occurred at ycur facility and datermine whether any significant deviations frca expected performance occurred.
If any sicnificant deviations are fcund, provide the details and an analysis of the significance and any ccrrective actions taken.
This caterial may be identified by referente if previcusly submitted to the U.C.
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F.e v i e.4 the acticns required by your c? rating prc:ed; es for ccping i ith transients.
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Recognition of the possit'lity of forming voids in the primary coolant system large enougt. to ccc;r:nise the core ccoling capability.
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0,cerator action required to prevent the formaticn of such voids.
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Operator action required to ensure continue'd ccre cooling in the event that such voids are formed.
4.
Review the actions requested by the cperating precedures and the training instructions to assure that operators do not override autccatic
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actions of engineered safety features without sufficient cause for doing so.
5.
Review all safety related valve position: and pcsitiening require-m.ents to assure that engineered safety features and related equip-gent such as the. auxiliary feedwater system, ccn perform their intended functions.
Also revicw related procedures, such as those
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to transfer potentially radicactive gases and Tiquids out of the containmen,e.o assure that undesired pum? lag or rac,ioactive liqui,ms t
anc gases will not occur inadvertently.
In particular assure that such an occurrence would not be caused by the resetting of engineered safety features instrumentaticn.
List als suca sys ens and indicate:
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Whether interlocks exist to prevent transfer when high radiation indication exists and,
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Whether such systems are isolated by the containment isolatica si gnal.
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Revieu your pror?t reporting procedures for CRC notification to assure very early notificatica cf serious events.
int c2talled results of these reviews shall be submitted within ten d.ays or he receip
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79-05
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Er.clcsed is IE Eulletin No. 79-05, which rec,uires actior by you '!ith regard to you pcwer reactor facility (ies) with an operating license cr a construction permit.
3nculd you have any questions regarding this Sulletin or the actions required by you, please ccntact this office.
Sincerely, Signature
(?.egional Director)
. -.. -, -,-.. e S.
. a,s
+
I'~ 3 u'l 'l e's '. n io. '/ 9 -0 ~a
- 1..
c s
and Enclosures 2.
List of IE Sulletins issu'ed in the past 12 rc.onths e
O O
A
- a. < J
(Oref t letter to eli power r~cactor facilities with an cperating license c'." c cons truc tion per. nit)
IE Sulietin !.'c.
79-05 e m-, s. e. =..,.
- c
. The enclosed Bulletin 79-05 is forwarded to vcu for informaticn.
IM w ri t c.en response is required.
If you cestre additiona,: inrorma icn regarding this matter; niease contact this office.
The Preliminary fictification of the subject incident (Enclosure 1) will continue to be a.
_hese will be Torwarcec to you.as Iney are issucc.
i 1ssuet; peric 1cally.
Sincerely,
.n 1 -...,t..,.
3 _ e
( O.n n : n... c-1 D:...- 'vor.)
3i cm
Enclosures:
1.
IE Sulletin i:o. 79-05 and Encicsures 2.
List of IE Bulletins issued ia the past
~
, 7....o s *u.,. s-s p.
a
[ I\\
8 b.L
'tL
Efwln.Sno.c 2 te m
A less of offsite power occurred at Osvis Eesse. On !!cventer 29, 1977, which resulted in shrinkage of t.ie primary ccoiant volume to the degree that pressurizer level indication aas lost.
A reccrendatien to convey this inforcation to certain hearing boards resulted in the attached discussion and evaluation of the event.
This discussion includas a rev ew or a loss or_ r_ee:,wa,cer sa,iety analysis assuming :orced T.cw,
_3 unich predicts disperseg. primary system volu;ing, but,no loss of core cccling.
Durir.; the Three Mile Island event, however, the forced flcu appears to have been terminated during the transient.
e J. t.J
- s.
- u.
--,u,iietin i,0.
/ c; -v o-it s c
nclosure c
Ipril 1, 1979 Page 1 of 3 LISTII:G OF IE BULLETit:5 ISSUED IN LAST TUELVE MO:iTHS Culietin Subject Date Issted Is:ued Tc I:o.
75-05 Malfunctiening of 4/14/78 All Power Reactor Circuit Breaker Facilities viith an Auxiliary Contact OL cr.C?
Me chan i s.,.-Gene ral Model CR105X 78-05 Defective Cutler-5/31/78 Ali Pcwer Reactor Hammer, Type M Relays Facilities with an ilith CC Coils' OL or C?
78-07 Protection afforded 6/12/73 All ?cwer Reactor by Air-Line Resoirators Facilities with an and Sucplied-Air Ecods O!,, all class E and F Research Reactors with an OL, all Fuel Cycle Facil-ities with an OL, and all Priority 1 Material Licensees 78-03 Radi. tion Levels froa 5/12/78 All Power and reel Elec.ent Transfer Research Reactor (u'cas Facilities with a Fuel Element transfer tube and an OL.
78-09 BWR Dryweil Leakage 6/14/79 All B'.!R Power Paths Associated with Reactor Facilities
. Inadequate Drywell, with an OL or CP Closures 78-10 Sergen c terson 6/27/73 All 5"R ?cweb a
Hydraulic Shoch Reactor Fccilities Supcresser Accumulator uith an OL or C?
Spring Coils 4o o c r>
- 1. a
- t. * * '. s 4
g e
e
II Sulletin Mo. 79-05 Enclosure April 1, 1979 Paga 2 of 3 LISTING OF IE BULLETIGS I S S"r D I n" i_n' s i t,. c' ". c_
1". m."u s.cu.
m Eulietin Subject Date Issued Issued To Lo.
. 78 Examination of Mark I 7/21/78 BWR Pcwer Re~ actor i
Centain. ent Torus Facilities for Welds action :
Peach Sottom ~ ar.d 3, Quad.C aes 1 and 2, Hatch 1, Monti-celic and Vermant Yarkee 78 -12 Atypical Weld Material 9/29/73 All Pcwer Reactor-in Reactor Pressure Fac41ities with an Vessel Weids OL or C?78-12A Atypical Weld Material 11/24/78 All Pcwer Peactor
'in Reactor Pressure Facilities with an Vessel '..'el ds OL or C?78-125 Atypical Weld Material 3/19/79 All Pcwer Reactor in Reactor Pressure Facilities uith an Vessel Helds CL or C?
78-13 Failures In Source Haads 10/27/78 All general and cf Kay-Ray, Inc., Gauges specific licensees I" cels 7050, 70503, 7051, uith the subject 70518, 7060, 70503, 7061 Kay-Ray, Inc.
and 70613 gauges 78-14 D'eterioration of Buna-H 12/19/78 All GE EWR facilities Components In ASCO with an CL cr C?
Scienoids 79-01 Environmental Qualifica-2/3/79 Ali Pcwer Reactor tion of Class IE Ec,uipment Facilitics with an OL cr CP n <-
a, e,
J. L 3 r.
-)
IE Sulictin ::o. 79-05 Enclosure Page 3 of 3
. April 1, 1979 LISTIt!G 0.0 IE CU'_LETINS ISSUED Ill LAST Th'ELVE ;'.C.THS Bulletin Su'aj ect Date issued Issued ~To
!!o.
79-02 Pipe Support Base Plate 3/2/79 All Power Riactor Designs Using Concrete Facilities with an Er.pensice enchor Bolts OL or CP 79-03 Lcngitudinal Held Defects 3/12/79 All Pcwer Reactor In AS:1E SA-312 Type 304 Facilities with an Stainless Steel Pipe Spccis OL or CP Manufactured By Youngsto'.n Welding and Engineering Co.
79-04 Incorrect Ueights for 3/30/79 All Power Reactor Swing Check Vaives Facilities with an Manufactured by Velan OL or CP Engineering Corporatica G
o k.h
IE Culletin "o.
79-65 April 1, 1979
.a".u': 7_ " c :n, _ f ' r A ". _:t_..n" I n u,.a.,h, _ r -
c"..,'. m"... ". mi m. _ s 2'
- o..p; c.; 5.cn o, 5'J 7 ~"C C H:r.K ". r'..I.v. :.3 n
n--.
,a
.- t v.
ui CORPORATIOil Distribution:
Technical Assistant, CCM (Chaircan's Office)
H-ll49 George Eysypontt, Technical Assistant, OCM (Gilinsky)
Hli49 John C. Guibert, Technical Assistant, OCl. (Kennedy)
Hil49 Hugh L. Thompson, Technical Assistant, OCM (Bradford)
Hil49 George D. Sauter, Technical Assistant, OCH (Ahearn2)
Hil49 SECY H-1149 A. P. Kennake, Acting Director, PE H-1007 L. Bicksi.it, Genarc! Counsel H-1047 R. F. Fraley, ACRS H-1015 L. V. Gossick, E00 MNS3-E209 J. R. Shea, Dir., DIP MN53-8iO3 J. J. Fouchard, Director, PA MN53-3709
- 11. M. Haller, Director, kPA MNSS-12105 C. Uayne Kerr, Asst. Dir., SA:S?
HN53-7210A
. J. Liebercan, ELD MNES-950?
R. S. Minogue, Dir., SD NL-5550 C. A. Arlotto, Oir, DES:SD NL-5550 W. J. Dircks, Dir., NM55 55-953
'5.
Levino, Dir., RES 55-1120 H. R. Danton, Dir., NRR Phil-423 R. S. Soyd, Dir., DFM:NRR Phil-253 D. F.. Ross, Deputy Director, DPM:NRR Phil-278 V. Stello, Dir., COR:NRR PSil-542 J. R. Miller, DOR:NRR Ptil-21G
~
D. G. Eisenhut, Dap. Dir., DOR:NRR Phil-255
.R. H. Vellmer, Asst. Dir., SP: DOR:NRR P-514 G. C. Lainas, Chief, PSB: DOR:liRR Phil-416 S. K. Grimes, Asst. Dir., E/P: DOR:NRR Phil-370 R. J. Mcttson, Dir., DSS:NRR Phil-202 W. P. Haass, Chief, OAB:0AO:NRR P-320
.J.
G. Davis. Acting Directcr, IE D.
incapson, h.0va:I:.
R. C. Paulus, XCOS:IE L. N. Undar.tocd, XC05:IE (Original)
H. D. Thornburg, RCI:IE G. W. Reinmuth, RCI:IE N. C. Moseley, ROI:IE E. L. Jordan, ROI:IE 5.
- c. aryan,
,0 r t:1-J. H. Snierek, FFMSI:IE o.
L. C. Higginbothea, FFciSI:IE 3"y
'"d-E. M. Mc.iard, SI:IE L. I. Cobb X0MA:IE D.C. Kirkpatrick, IE contrct T.: File;
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-3 an experiench with such transients shov, however, that they can be d
.-s sustained eithout co.pronising the safety of the reac:cr.
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'3 concera caused by such transients is. that they night cause voidin~* in
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NUC1. EAR REGULATORY COMMiss!CN
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.F April 5,1979
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ME.WJPjdiCUM FOR:
- 3. H. Grier, Director, Region I 5
J. P. O'Reilly, Director, Regien II PZ.fC J. G. Kappler, Director, Regien III
~M K. V. Seyfri t, Direccor, Regica IV R. H. Engelken, Director, Region V
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Hor.an C. Mcseley, Director, Division of Reactor 24 Operations Inspecticn, CIE w_m
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IE BU1.LITIN 79-05A, NUCLEAR INCICENT AT THREE HILE
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.5 The subject IE Bulletin should be dispatchad for action cy April 5,
- +~
~ 979, to all 39 pcwer reacter facilities with an cperatinc license.
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The Bulletin must be faxed.to B&W facilities by Aprii 5.
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Subject bulletin and enclosures shculd also be dispatched for infor:a-tien to all other power reactor facilities with an operating license h.
4.M and to all power reactor facilities with a constructicn gemit.
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The text. ui Use Bulletin, Enclosures thereto and draft istters -M-9.c th'@
licensee are enclosed for this purpose.
The continuing oreliminary Notifications of the incident shculd continue to be forwarded as they a
i_,
are received in actordance with the transmittal memorandum for
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' 0cmar/p. Moseley, Director 23 93i Divisi'On of Reactor Operations
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Enclosures:
1.
Draft Transmittal Letter y{q
~
to all BW Operating' Licensees
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Draft Transe.ittal Letter
-2 to all other C;eratina Licensees
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and Ccastruction Fernit Hclders.
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(w/ enclosures - 2)
..27-CONTACT:
D. C. Kirkpatrick, IE
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Enclosed is IE Sulletin No.79-05A, which recuires action by you with w
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.'T regard to " cur pewar re.: tor: facility (f es) with an operating '.icense.
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Should you have any questions regarding this Bulletin or the actions M
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P' required by you, please conuact this office.
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Sincerely,
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Enclosure:
151f IE Bulletin No.79-05A re with Enclosures
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Tne enciesed Bulletin 79-05A is forwarded to you for information.
NO written resper.m is required.
I,. ycu desire addi.lena t i n t o r=a,e,. c n
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recarding this natter, please contact this office, m_
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Signature xr,. -
(Regional Director)
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-g fE-UNITED STATES NUCLEAR REGULATORY COMMISSION
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~~~~-
OFFICE OF INSFECTION AND ENFORCEMENT n.
W WASHINGTON, DC 20555 W
APRIL 5, 1979 g?$f'.
IE Sulletin 79-0E
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NUCLEAR INCIDENT AT THREE MILE ISLAND - SUPPLEMENT 49NQ W
Cescriptien of Ciretr: stances::
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Preliminary informatien received by the NRC since issuance of IE
~
Eulletin 79-05 on April 1,1979 has identified six potential h= nan, design and mechanical failures which resultec in the core damage and
~
radiation releases at the Three Mile Island Unit E nuclear piant.
The
[f' infermation and acticns in this supplement clarify and extend the origina
~;i. c Bulletin and transmit a preliminary chrcnology of the TMI accident
?g threugh the first 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> (Enciosure 1).
1.
At the time of the initiating event, loss of feedwatar, both of the JE^.fk auxiliary feedwater trains were ialved out of service.
~ ~ ~ ~
_g.
The pressurizer electrebatic relief valve, which opened during 7)$['
2.
the initial pressure surge, failed to close when the pressure
~r 35E h decreased below the actuation level.
_w-Fo11cwing rapid depressuri:ation of the pressuri er, the pressurize
_,3. 3 3.
Mi((..
level indication may have lead to errenecus inferences of high
?""
level in the reactor coolant system.
The pressurizer level indics:
[222.'
apparently led the operators to prematurely terminate high pressure e_.
injection flow, even though substantial voids existed in the reacto
- ~
- = ;:r coolant system.
n..
M Because the containment does not isolate en high pressure injecticn 4.
(HPI) initiation, the highly radicactive water frcm the relief valve discharge was pumped out of the containment by the automatic Initiation of a transfer pump. This water entered the radioactive j[$[.
waste treatment system in the auxiliary building where scue of it overficwed to the floor.
Outgassing from this water and discharce through the auxiliary building ventilaticn system and filters was 0;;...
... T the principal source of the offsite release of radioactive noble d57' gases.
'JfQ.
IIII 5,
Subsequently, the high pressure injecticn system was intermittent 1,
- s, operated attempting to control primary coolant inventory losses
- [
through the electromatic relief valve, acparenGy based en pressuri:er level indica:icn.
Due to the cresence of steam and/cr 1-noncondensible voids elsewnere in the reactor ccclant system,
_,,,7 '
this led to a further reduction in primary ecolant inventery.
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IE Bulletin 79-05A April 5, 1979 Page 2 of 5 M
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Tripping of reactor ccolant pu=s during the ccurse cf the transient.
C to protect against pump darrage due to puin vibration, led tc fuel C
damage since voids in the reactor coolant system prevented natural 2*
circulatien.
2,
- e.
Acticns To Ea Taken by !.icensees:
M!!s
-2' For all Babcock and Wilecx pressuri:ed water reactcr facilities wf th an operating license (the actions specified below replace those specified t'A.
in IE Bulletin 79-05):
=- m X._
1.
(This item clarifies and expands upon item 1. cf IE Sulletin 79-C5.)
m
- 2. ^ -
~7 In additicn to the review of circumstances described in Enclosure 1 of IE Eulletin 79-05, review the enclosec' preliminar'v chronology cf D
the TMI-2 3/2S/79 accident.
This review should be directed toward understanding the sequence of events to ensure against such an C.
M accident at your facili.y(ies).
m=. -
2.
(This item clarifies and expands upon item 2. of IE Sulletin 79-C5.)
M b,,_,
ReYiew any transients similar to the CaVis EeSsa event (EnclCsure 2 L
cf IE Eulletin 79-05) and any others which cantain similar elements Trce the enclosed chrcnoicay (Encicsure 1) which have occurred at your facility (ies).
If any significant deviations frca expectec
~ ~'
-L perfemance are identified in your review, provide details and an
..f analysis of the safety significance together with a description af an~v corrective actions taken.
Reference may be rade to previcus
' - ~
information provided to the NRC, if appropriate, in respcnding to 1@-
this item.
2
(
3.
(This item clarifies item 3. of IE Sulletin 79-05.)
Review the actions required by your operating precedures for ccp'ng C
with transients and accidents, with particular attention to:
Reccgnition of the : possibility of forming voids in the primary T-a.
7~
coolant system large enough to comprcmise the core c0oling capability, especially natural circulation capability.
m, k.iS b.
Operator action required tc prevent the fermaticn of such
-- W vcids.
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Operator action required to enhanca ccre ecoli_ng in the event
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D' such voids "are fomed.
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IE Niletin 793A Acril 5.1579 Page 3 cf 5 i
(Tai s i te:s cl ar' f f es a r.d u,. ands u;xn i t=s 4. c' I E ki l etin MS. )
4 t
W.ev the acti::ns directed by the ccerating precadurts and t eining 1..strxciens to ensurs tra::
C,.er:ters do not everride autom.atic actions of engineered a.
sa f ety fea t'J res.
I b.
C rating precedures currently, er ar-revjsad to specify g
trat if the hign pressure injecticn (HFI) sysam has been autreatically actuated because of low pressure ccndition, it c:ust remain in cperation until either:
(1)
Ecth icw pressure injecticn (LPI) pur:s are in c;:eratien and ficwing at a rate in excess of 1000 spa each and the situatien has been stable fcr 20 minutes, or (2)
Tne HpI system has been in cperation for 20 ninutes, and all hot and cold leg temperatures are at least 50 degrees beicw the saturation te cerature fer the existing RCS pressure.
If 50 degree subcccling cannet be :naintained after HPI cutoff, the HpI shall
'.,e reactivated.
Operating precedures currently, or are revised to, specify c.
that in the event of HPI initiati e with reacter c:clant pumos (RCp) operating, at least v..e RCP per loop shall remain operating.
d.
Operaters are provided additional infon stien and instr;:ctions to not rely upon pressurizer level indication alene, but to also exa:nine pressurizer pressure and other plant paraceter indicatiens in evaluating plant conditiens, e.g., water invent:ry in the reacter primary system, (This item revises item 5. of IE Sulletin 79-05.)
5.
Yerify that emergency feedwater valves are in the open pcsition in accordance with item 8 belv.
Also, review all safety-relatad valve pcstttens and pcsitiening requirements to assure that valves are positioned (cpen er closed) in a manner te ensure the precer cper:tien of engineered safety features.
Als] revi=w relaced precedures, such. as these for rahtenance and testing, to ensure that such valves are returned to their cor ec: pcsiticn:
fc11cving necessary :anipulaticns.
4 4) 6" * O
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!E Eclietin 79-05n npril 5, 1979 Page 4 of 5 6.
Review the containment isolation initiation design and procedures, and prepare and implement all changes necessary to cause containment isolation of all lines whose isolation does not degrade core ccoling capability upon automatic initiation of safety injection.
7.
For manual valves or manually-operated motor-driven valves which
~
could defeat or compromise the flow of auxiliary feedwater cc the steam generators, prepare and implement procedures which:
a.
require that such valves be locked in their correct position; or b.
require other similar positive position controls.
8.
prepare and implement immediately procedures wSich assure that two independent steam ga.nerator auxiliary feedwater flow paths, each with 100% ficw capacity, are operable at any time when heat removal from the primary system is through the steam generators.
When two inde-pendent 100% capacity ficw paths are not available, the capacity
.shall be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the plant shall be placed in a cooling mcde which does nec rely on steam generators for cooling within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
When at least one 100% capacity flow path is not available, the reactor shall be made.subcritical within ene hour and the facility placed in a shutdown cooling mcde which does not rely on steam generators for cooling within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or at the maximum safe shutdown rate.
S.
(This item revises item 6 of IE Bulletin 79-05.)
Review ycur operating codes and procedures for all systems designed to transfer pctentially radioactive gases and liquids out of the primary containment to assure.that undesired pumping of radicactive liquids and gases will not occur inadvertently.
In particular, ensure that such an occurrence would not be caused by the resetting of engineered safety features instrumentation.
List all such systems and indicato:
Whether interlocks exist to prevent transfer when high radiation a.
indication exists, and b.
Whether such systems are isolated by the centainment isolation signal.
I Y
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IE Bulletin 79-05A April 5, 1979 Page 5 of 5 i
i 10.
Review and mcdify as necessary your maintenance and test procedures to ensure that they require:
a.
Verificaticn, by thspection, of the cperability of redundant safety-related systems prior to the removal of any safety-related system frca service.
b.
Verificatien of the cperability of all safety-related systems when they are returned to service felicwing m::intenance or testing.
c.
A means :f notifying involved reacter operating persennel whenever a safety-ralated system is removed frem and returned to service.
11.
All operating and maintenance personnel should be rade aware of the extrse seriousness and:censequences of the simultaneous blocking of both auxiliary feeder trains at the Three Mile Island Unit 2 plant and other acticns.taken during the early phases of the accident.
12.
Review ycur prcept reporting precedures for NRC notification to assure very early notificaticn of serious events, For Babcock and Wilcox pressurized water reacter facilities with an cperating license, respond to Items 1, 2, 3, 4.a and 5 by April 11, 1979.
Since these items are:substantially the same as those specified in IE Bulletin 79-05, the required date for respor.se has not been changed.
Respond to Ite s 4.b thrcugh 4.d, a d 6 thrcush 12 by April 16, 1979.
Reports should be submittad to the Directer of the appropriate NRC Regional Office and a copy shculd be feraarded to the NRC Office of Inspection and Enforcement, Division of Reacter Operaticns Inspection, Washington, CC 20555.
.Fer all ctrer reitters with an cperating license or constructicn pennit, this Bulle;in is for information purposes and no written respense is a
rec.ui red.
- iG
..7 9 proved by C.o 3 180225 (R0072); clearance expires 7-31-80.
Approval was given under a Snet clearance specifically for identified generic vl problem:.
i Encicsures:
i 1.
Preliminary Chrcnology of TMI-2 3/28/79 Accident Until Ccre Cooling Restored.
2.
List of IE Bullet. ins issuad in last 12 mcnths.
} 4}
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Enc 1csure 1 to IE Bulletin 79-05A April 5, 1979 PRE 1IMINARY CHRCNOLOGY OF TMI-2 3/23/79 ACCIDENT UNTIL CORE CCCLING RESTORED TIME (Approximate)
EVENT about 4 AM Loss of Candensate pump (t = 0)
Less of Feedwater Turbine Trip i'
t = 3-6 sec.
Eleccrocatic relief valve opens (2255 ' psi) to relieve pressure in RCS t = 9-12 sec.
Reacter trip en high RCS pressure (2255 psi) t = 12-15 sec.
RCS pressure decays to 2205 psi (relief valve shculd have closed) t = 15'sec.
RCS hot leg temperature :eaks at 611 degrees F 2147 psi (450 psi over saturacien) t = 30 sec.
All three auxiliary feedwater pumps running at pressure (pumps 2A and 28 started at turbine trip).
No flow was injected since discharge valves were closed, t = 1 min.
Pressurizer level indication begins te rise rapidly i
t = 1 min.
Steam Generators A and 3 seccndary level
- very icw - drying cut ever next ccuple of i minutes.
t = 2 min.
ECCS initiation (HPI) at 1500 psi
'~~
1 t = 4 - 11 min.
Pressuri:er level cff scale - high - ene HpI puma manually tripced at about 4 min.
30 sec.
Second pump tripped at abcut 10 min. 30 sec.
- = 6 min.
RCS flashes as pressure bottoms cut at
,i 1350 psig (Hec leg temperature cf SE4 degrees F) t - 7 min., 20 sac.
Reactor building sump pump came en.
,e c-
],
t 1: La
I
! VEllT iIHE E
t a
t = 8 min.
Auxiliary feedwater ficw is initiated by cpening cicsed valves t = 8 min. 18 sec.
Steam Generator B pressure reached minimum t = 8 min. 21 sec..
Steam Generator A pressure starts tc re:cver t = 11 min.
Pressurizer level indicaticn ecmes heck en scale and decreases t = 11-12 min.
' Makeu, Pump (ECCS HpI ficw) restarted by operators t = 15 min.
RC Drain / Quench Tank rupture disk blows at 190 psig (setpoint 200 psig) due tc centinued
' discharge of electrcmatic relief valve t = 20 - 60 min.
System parameters stabilized in saturatsd condition at abcut 1015 psig and abcut 550 degrees v.
t = 1 hcur,15 min.
- Operatcr trips RC pumps in Lecp B 1
t = 1 hcur, 40 min.
(OperatcrtripsRCpumpsinLcepA i
t = 1-3/4 - 2 hcurs
' CORE SEGIUS HEAT UP TRANSIENT - Het leg temperature begins to rise ca 520 degrees F (off scale within 14 minutes) and cold leg temperature drops to 150 dagrees F.
l(HPIwater) t = 2.3 hcur Electromatic relief valve isolated by operator after S.G.-B isciated to prevent ilerkage t = 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />
.RCS pressure increases tc 2150 psi and electromatic relief valva cpened t = 3.25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br />
.RC drain tank pressure spike of 5 psig t = 3.8 hcurs
'RC drain tank pressure spike of 11 psi -
RCS pressure 1750; centainment pressure increases from 1 to 3 psig t = 5 hcurs
' Peak containment pressure of 4.5 psig t
I t = 5 - 6 beurs
'!RCS pressure increased fre= 1250 psi to to 2100 psi eo SU (l t: (
. TIME
'EV5NT t = 7.S hours Operator opens electrocatic relief valve to depressurize RCS to attempt initiaticri of RHR at 400 psi t = 8 - 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> RCS pressure decreases to abcut 5C0 psi Cere Flcod Tanks partially discharge t = 10 hour1.157407e-4 days <br />0.00278 hours <br />1.653439e-5 weeks <br />3.805e-6 months <br /> 28 psig centainment pressura spike, centair.m2nt sprays iniciated and stopped after 500 gai, cf NaCH injected (about 2 minutes of operatien) i t = 13.5 heure 71ectromatic relief valve closed to rspressurire RCS, collapse veids, and start RC pump t = 12.5 - 15 hcurs -
RCS pressure increased from 550 psi to 2200 pst t = 15 hours1.736111e-4 days <br />0.00417 hours <br />2.480159e-5 weeks <br />5.7075e-6 months <br /> RC pump in Locp A started, het leg temperature decreases to 560 degrees F, and cold leg temperature increases to 400 degrees F.
indicating ficw through steam generator Thereafter S/G "A" steaming to condensor Condensor vacuum re-established RCS cocied to abcut 2E0 degrees F.,
1000 psi Now(4/4)
High radiatien in centainment
, All core theraccouples less than 460 degrees F.
Using pressurizer vent valve with small makeup ficw Slcw cooldcwn RS pressure negative w
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s) t.
t.
J
IE Eulletin No.79-05A Enclosure April 5, 1979 Page 1 of 3 LISTING OF IE BULLETINS ISSUED IN LAST TdELVE HONTHS Sulletin Subject Date Issued Issued To NC.
78-05 Ralfunctiening of 4/14/78-All P0wer Reactor Circuit Breaker Facilitics wi-N an Atxilicry Centact OL or CP Mechanism-General Model CR105X 78-06 Defective Cutler-5/31/78 All Power Reactor Hammer, Type M Relays Facilities with an With DC Coils OL or CP 75-07 Protection affcrded 6/12/78 All Power Reactor by Air-Line Resp.irators Facilities with an and Supplied-Air. Hoods OL, all class E and F Research Reacters with an OL, all Fuel Cycle Facilities with an OL, and all Priority 1 Material Licensees 78-C8 Radiation Levels from S/12/78 All Pcwer and Fuel Elesent Transfer Research Reactor Tubes Facilities with a Fuel Elesant transfer tube and an OL.
78-09 EWR Drywell Leakage 6/14/79 All EWR Power Paths Associated:with Reactor Facil' ties Inacecuate Drywell with an OL or CP C1csures 78-10 Bergen-Paterson 6/27/78 All EWR Power Rydraulic Shock Reactor Facilities Suppressor Accumulater with an OL cr CP Spring Coils e l
(
7
IE Eulletin No.79-05A Enclosure April 5, 1979 Page 2 cf 3 LISTI.NG OF IE BULLETINS ISSUED IN LAST TWELVE H0tmiS Bulletin Subject Date Issued Issued To Nc.
78-1' exacinction cf Mark I 7/21/78 EWR Pcwer Reacc0r Ocncaincent Torus Facilities for Wel ds-actien:
Peach Sotten 2 and 3, quad Cities 1 and 2, Hatch 1, M:nti-cello and Veracnt Yankee 78-12 Atypical Weld Haterial 9/29/78 All Pcver Reacter in Reactor Pressure Facilities with an Vessel Velds OL or CP 7S-12A Atypical Weld Material 11/24/78 All Pcwer Recctor in Reactor Pressure Facilities with'an Vessel Welds OL cr CP 75-123 Atypical Weld Ma'erial 3/19/79 All Pcwer Reacter t
in Reacter Pressure Facilities with an Vessel Wcids OL or CP 78-13 Failures In Source Heads 10/27/78 All general - '
~of Kay-Ray, Inc., Gauges specific licensees Mcdels 7050, 70505, 7051, wit' the subject 70513, 7060, 70508, 7C61 Kay-Ray, Inc.
and 70613 gaugts 78-14 Deterioration of Suna-N 12/19/78 All
..". facilities
^~
cc=cenents In ASCO t
m -o or CP Solenoids 79-01 Envircrrmental Qualifica-2/8/79 Ai e er Reacter tien of Class IE. Equipment Fac. nties with an OL cr CP s
13 t'GO
IE Bulletin No.79-00A Enclosure April 5, 1979 Page 3 of 3 LISTING OF IE BULLETINS ISSUED IN LAST TWELVE HONTHS Eulletin Subject Date Issued Issued Tc No.
79-02 Pipe St; pert Case F; ate 3/2/79 All Power Reacter Designs Using Concrete Facilities witn an Expansica Ancher Bolts OL cr CP 79-03 Lengitudinal Wald Defects 3/12/79 All Pcver Reacter In ASHE SA-312 Type 304 Facilities with an Stcinless Steel Pipe Spcols CL or CP Kanufactured 5y Youngstown Welding and Engineering Co.
79-C4 Incorrect Weights for 3/30/79 All Pewer Reactor Swing Check Valves Facilities with an Manufactured by Velan OL -- CP Engineering Carperstion 79-05 Nuclear Incident:
4/1/79 All E&W Power at Three Mile Island Reacter Facilities with an OL i
t 4
3 18'
('
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NUCLEA?. FEGULATORY COPJi!SSION OFFICE OF INSPECTION AND ENFCRCE':ENT WASHINGTON, D.C.
INCIDENT MESSAGE FORM TO:
Cc=issioners FROM:
Lee V. Gossick, EffT Att
..ied is a preliminary chronology of NRC actions in connection with Tiu that has been prepared in connection with the April 10 hearing.
Copies have been provided OCA, OPE and EDO offices involved.
\\
\\
cc:
Commissioners (10) - 2 each OPE (1)
OCA (1)
L. V. Gossick (1)
E. C. Case (2)
J. G. Davis (2)
SP (1)
!;PA (2)
DATE:
a/09/79 TIME:
1915
Contact:
Steve Ccnver,l'?A 1L3 1
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/VR S :a NRC REACTION TO THREE MILE ISLAND ACCIDENT CHRONOLOGY OF EVENTS (PRELIMINARY)
Attached is a chronolcgy aof the ccr:JniCatiCns and actions regarding the notification to NRC of the TMI accident, notifications made by NRC, actions taken and various related communications.
The source for the entries are as shown, and, except for the entries whose source is shown as OC Tape (talephone conversations recorded in the NRC Operations Center in Sethesda), must be treated as preliminary in nature and subject to later confirmation or clarification.
It must also be noted that not all calls to and from the NRC OC were recorded due to saturation of the cortunications system requiring use of telephone lines not recorded by the twenty channel recorder in the Operations Center.
N.
.R_
f Cate/ Time Source Activity
ednesday, March 20
$U 4:00 None Incident sequence begins.
5:50 Cperaticas Center Licensee declares site emergency (OC) tape 7:02 SP Folicwup w/PA Licensee notifies PEMA (Pennsylvania Emergency Management Agency) of site emergency.
7:10 - 7:45 Region I Licensee attempts to contact Region I.
Duty officer and Dep. Director en route to office when beeper sounds.
7:24 OC tape Licensee declares general emergency.
7:45 Peg. I Upon opening switchboard, Region I receives. message from licensee 7:50 Reg. I Region I contacts TMI control recm; maintains open line.
7:55 Reg. I Region I classifies event as a Level 1 severity inc.ident in accordance with Regica I incident response plan.
8:00 Reg. I Region I Incident Response Center activated; John Davis, HQs., notified by Boyce Grier and also by Public Affairs (Fouchard notified by Region I Public Affairs).
8:05 Various Jonn Davis orders Hcs Operatiens Center activated, Region I State Liaison attempts to ccntact PA Eureau of Rad.
Health.
8:20 Reg. I Regica I contacts independent measurement van (at Millstone site) and orders it dispatched to IMI site.
p.
s 1
.~3-~
Cate/ Time Source Activity 8:23 OC tape Phone call frcm Weiss and Moseley to Grier; Jchn Davis calls Gossick, who was in conversation with Foucnard.
8:25 Incoming Te!- Log Gossick calls Davis 8:30 Reg. I PA State Police informed that NRC emergency vehicle would be en route.
8:31 OC Tape Moseley notifies Stello &
Eisenhut; Stello says he will send radiclagical experts to OC 8:32 OC Tape John Davis calls L.V. Gossick, decision made to convene EMT 8:34 CC Tape Jchn Davis calls Denton's office; speaks to Case.
8:35 OC Tape Davis calls He..drie's office; speaks to Bill Dorie.
8:40 (appran)
Gessick & Case arrive at Operations Center 8:40 GC Tape Mike Wilbur calls Soyce Grier, cbtains technical information.
8:45 Reg. I Five ins 3ectors (including health raysicists) with radiatir.n monitoring equipment leave far site.
8:46 OC Tape Davis calls Dorie, asks for Ccmm. Gilinsky in Chairman's absence; Gilinsky not in yet.
8: 48 OC Tape Dudley Thcmpson notifies Tom Carter, NM55 No NMSS act. ion required.
8: 49 OC Tape Ward notifies J. Davidson, NMSS, to make I AT notificaticn.
8.50 Reg. I Lcg Licensee calls Reg. I with current status report.
1ei f}(?T3
4 Date/ Time Scurce Activity S:50 Reg. I State Liaison contacts PA Sureau of Rad Health S:52
'" Tape Davis notifies Comm. Kennedy (First Cc=missioner contacted)
Davis reports that he, Gossick, Case & Fouchard are manning EMT at 0.C.
Kennedy says he will notify Cc=missioner Gilinsky.
8:56 OC Tape Gossick attempts to reach Gilinsky through Bill Dorie and through Gilinsky's office.
Gossick talks to John Austen and requests that Dorie reach the Chairman.
8:57 OC Tape Davis notifies Commission Ahearne 8:59 OC Tape Bernie Weiss calls COE Emergency Operations Center 9:00 GC Tape Sill Ward informs Randy Pine (CA).
Randy Pine indicates that she will inform local Congressmen (Heinz &-Schweiker) and Rep. __.
9:00 Reg. I Second vehicle leaves Region for site (investigator plus inspector); Region I contacts RAP who has already been notified; two teams organized and standing by.
9:00 Bob Ryan Ryan notified by SP Region I personnel.
Arrives Hqs. OC 9:35am 9:02 OC Tape Weiss notifies EPA (Floyd Galpin) 9:08 SP n
'^e Joe Fcuchard calls Carl Abraham, Reg I Public Affairs k
Date/ Time Source Activity 9:10 OC Tape Gossick calls Congressional Affairs Office.
Rancy Pine informs Gossick that CA had received several incuiries from local Congressmen.
9:10 to 9:30 OCA OCA places call to majority and minority 5taffs of House of Subcccmittee on Energy and Environment, iouse Subccmmittee on Energy and Pcger and Senate Subcommittee on Nuclear Regulation as well as Senators Heinz and Schweiker and Representatives Walker and Ertel to adivse of declaration of site emerga.my at Three Mile Island 9:06 OC Tape Bill Ward informs Ccmv.unications Branch 9:10 OC Tape Grier calls..sseley to explain technical aspects of incident.
9:11 inccming Log Gilinsky calls Gossick and Davis 9:16 OC Tape Fcuchard notifies CCE Public Affairs Office (Scb Dulin).
AFTER 9:15 AM Other NRC personnel began arriving at Headcuarters Operations Center (OC Tapes not yet scanned for times after 9:15 am) 9:15 0C Notifications White Housa Situation Rocm Log contacted 9:27 Incoming Log Defense Civil Preparedness Agency (DCPA) Calls Jce Hegner 10:05 PN79-67 Reg. I response team arrives at site 10:05 Reg. I Reg I contacts EPA H;s. (also attempts to contact EPA: III)
f.
Oste / Time Source Activity 10:05 to 10:10 Reg. I Discussion w/ RAP re ARM 5 aircraft survey.
ARMS people put on standby 10:15 Reg. I Onsite team informs PA Rad.
Health that they are available for questioning.
10:16 Incoming Log Conference call:
All Ccamissicners and Davis 10:20 SP Log Telephone to PA State Rad Health Dept. (Gerusky not available).
Call returned at 10: 45 (1st liaison established by Hqs) subsequent calls every 1.qur or two, starting about 5:25 pm to discuss status of sampling and monitoring.
10:30 to 11:30 OCA OCA calls principal oversight committees (including appro-priations subcommittees) and Pennsylvania representatives frca vicinity of site to adeise of release of radioactive materials.
10:30 Reg. I Reg. I contacts Delaware 10: 40 Reg. I Reg I contacts PA Governor's action center 10:45 Reg. I Reg I contacts NY State Energy Office 10:30 P R#79-54 First Press Release based on Preliminary Notification 10:40 SP Log Press Ccnference (from where?)
patched through to PA Rad Health Dept.
10:55 SP Log Tele;hene call to PA Civil Defense (second call to Operations Officer at 11:30 am).
Ih
- 'C u r
Date/ Time Source Activity 10:58 Inccainc Log White House Duty Officer to Weiss 11:00 Reg I second Team arrives at site and in centrol roca 11:35 Reg I F?A Regica III contacted 11: 45 Reg I NJ Dept of Energy contacted 11:55 Rag I State of MD, Pcwer Plant Siting council contactec
_P _M 12:04 Reg. I EPA Regicn III contacted 12:10 Reg I DOE (Valley Forge Office) contacted 12: 20 CCA OCA calls principal oversight committees and PA representa-tives regarding latest i n f o r-mation (In response to recuest from Henry Myers for technical information arranged for briefing by Mr. Stello) 1:00 Reg I Third vehicle departs for site 1:00 Reg'I Reg I contacts MD Health Dept.
1:01 Inccming Log.
Stello calls Henry Myers 1:12 SP Log SP calls VA Civil Defense 1:30 DOE Logs 00E advance party establishes ccr,and post at Capitol City Ai rpo rt 2:15 DOE Legs ARMS heliccpter arrives at site and begins tracking.
2:30 E E Logs ENL RAP arrives Capitol City Airport; st:pling begins 2: 45 Reg I State liaiscn contacts Gcverror's office Ccnnecticut 1..
e
t
- Cate/ Time Source Activity 3:00 SP Log
?rcposed NRC Press Reiesse cleared with PA Rad Health Dept 3:a5 PN 79-67 First formal preliminary notification report distributed by NRC 4:00 OCA Telephone briefing fcr Senate Subcommittee on Nuclear Regulation and Senator Heinz 5:00 PR 79-55 Second press release issued 5:15 Reg I NRC mobile lab arrives at site 6:0)
Reg I Fourth Reg I vehicle leaves for site 7:55 SP Log Call tc PA Rad Health Dept (ARMS data shows count is up, status of ENL monitoring activities).
6:15 SP Log PA Rad Health Dept acknowledges r eceipt of ARMS data and says they are keeping Governor informed.
17 Reg. I Log Reg I notified of decision to send NRR team to site; arrival expected next AM.
8:30 Reg I Fourth vehicle arrives on site B:30-Reg I NHC, State, RAP Team brief 9:45 Lt. Governor Scranton S
Region I Log Reg I notified that Salem providing equipment 9:00 SP Log SP verifies (how?) that FAA has not been notified.
10:00 -
11:00 Reg. I Reg I participates in Lt.
Governcr's press conference
.Ok P.fi
f
_ g.
Thursday. t' arch 29 CU 11:30 (FM) to 12:30 (AM)
Reg I Team briefs Governor Thornburgh 12:15 PR #79-65 Press Release 1:00 SP Lcg SP notifies Defense Civil Preparedness Agency anc read; press release.
2:00 SP Log SP telephones PA Emergency Management Agency, reads press release 2:10 SP Log SP tries to telephone Health Center for Disease Control (Atlanta) (PA radiological Health says they will try again in morning).'
8:30 SP Log SP calls H. Calley, EPA, to read press release and suggests he call Gerusky and offer assistance 9:00 Reg I Two additional vehicles (6 people) dispatched to site 9:30 SP Log Food and Drug Administration calls and offers to have Baltimere Field Office provide assistance in looking at focd pathways s
9:30 Commission briefed by Gossick, Eisenhut and Jordan at "h" Street 10:25 PN-79-67A
)3 sued 11:00 SP Leg SP tries to contact NY Bureau of Radiological Health (call completed at 12:17 pm) 11:05 SP Log SP calls NJ Dept. of Health.
11:30 CCA Chairman Hencrie and NRC staff brief menters of Stocommittee on Energy and Environment,
, other Members of Congress, and fg I'.(' [)
Ccngressicnal staff en status
-of incident.
. Date/ Time Source Activity 11:"5 SP Log SP calls Delaware Rad-Health Dept.
12:00 (Approx)
NRR team (Vollmer +7) arrive on site; Strasma (Region III Public Affairs) on site
_F _M 12:C5 SP Log SP returns call to Gov. Ray's (Washington) assistant.
12:10 SP Log SP. calls W.VA Rad Health contact 12:15 SP Log SP calls Va. Radiological Health (call finally completed at 1:15).
12:00 -
1:00 Reg I Vehicles 6 and 7 on site (total IE personnel:
17) 2:15 Reg I Congressional group (Hart, Udall, Heinz, et al) arrive observation center; receive briefing.
2:40 SP Log SP telephones. Fish and Wildlife Service.
3:00 PN-79-67E Licensee pulls thermolumi-nescent dosimeters from 17 fixed positions located within a 15 mile radius of site.
Dosimeters had been in place for three months and had been exposed for about 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> after incident.
Only two dosimeters showed exposeres above normal levels.
3:01 SP Log SP briefs (by phone) Md.
Radiological Health cn status of samples.
3:20 Reg I State liaison contact with Vermont i ci fll C)
f.
Cate/ Time Source
~ Activity 3:15 -
6:30 Reg I NRC representatives are called to State Capital to orief Governor and Lt. Governor prior to Governor's 5 C0 p.m.
press Ccnference.
3:35 SP Log In response to inquiry from i'innesota Rad. Health, SP gis os status briafing.
5:55 Reg I Log The Executive t.
nagement Team directs the lic 'see to stop dumping all water.
RI notifies HQ that stopping the dumping will cause backing of water into the Turbine Building.
(Late entry - the licensee has been dumping water to the river -- the water is.within TS limits WRT contamination.)
6:00 Log???
PA Rad Health says NRC can make decision en rad. water dump without checking further with them.
6:10 Reg I Lcg Licensee notifies NRC.that he is stcpping the discharge 5:30 Reg I Log Briefings provided by Met.
Edisen to Senator Schweiker, Congres; men Gooding (York),
Mike McCormack; Waller (Lancaster),
Weidler (L.I.,NY) 6:00 PN-678 NRC requests Met. Edison to terminate release of slightly contaminated industrial waste.
Permission to resume release granted at 12:15 am and coordinated with State.
State press release issued.
4:50 -
151 g). 4 Multiple attempts to reach 7:00 Reg. I EPA:III concerning industrial
'zaste dumps; finally centacted at 7:00 p.m.
12 -
Cate/ Time Source Activity 5:35 SP Log PA Rad Health calls back and asks hRC to hold river dump because of Governor's concern.
SP provides update on ARMS data.
7:05 SP Log Offer from DOE Emergency Assistance.
8:30 Reg I Call to Governor's Aide to inform of core damage 8:00 -8:30 SP Log Updated status reports to MD, WVA and US Sureau of Rad.
Health 10:05 SP Log PA Rad Health says "go" if NRC wants to have water dumped.
10:12 Reg I Lcg Industrial Waste Discharge verified to be off.
Friday March 30
$d 12:05 Reg I Log EMT asks IE/ site to relay to Met. Ed that NRC says OK to release industrial waste.
Notify NRC when release commences.
2:06 Reg I Log Industrial 'daste Tank over-ficwing onto ground 5:35 Reg I Log Fire in Unit One Aux. Building Basement - (picked up from intercom).
Fire in ventilation system.
8:00 SP Log Status report to EPA 8:20 SP Leg Status report to FDA, Eureau of Radiological Health 8:30 SP Log Status report to Md. Rad Health S:50 SP Log Call frcm FPA requesting 1 p<.
q<9 status m
s
. Cate/ Time Source Activity 9:06 Reg I Control roca personnel (Unit
- 1) hear anncuncament
- hat evacuation in a 10 mile radius around plant has been reccomended by NRC.
9:05 Reg. I Onsite inspector calls Region to verify that above was true.
Were teid recom endation was not afficial.
9:25 Reg I log otate notified of release; evacuation rum red; site does not plan to ca'il for evacuation.
9:15 -
10:10 SP Log SP calls PA Civil Defense re potential evacuation 9:.50 PN 79-675 Issued 10:00 Reg I Log Some confusion exists because State evidently has recc.mmended evacuation of Middletown (Occ.
Collins).
Plant /NRC has not recommended evacuation.
10:25 Reg I Log Ccemunication Lcst with Unit 2 Controi room 10:30 -
10: 45 Reg I Log State has advised residents within 10 miles to go inside and shut windows.
NRC position remains:
no evacuation /
unnecessary to take any special precautions.
10:47 Cmsr. Tel. Log Conference call between Gossick and Commissioners:
decision to send Denton to site.
11:00 Reg. I Unit 1 Control Recm becomes aware that an evacuation was suggested by Governor.
11:40 C sr. Tel. Leg Hendrie and Governor discuss evacuation.
1 Q ~ Q * ")
f Te:e/ Time Source Activity
'5 Reg I Log Release at 11:09 for ab;ut 15 secs.
12:03 Reg I Log Chairman of NRC reccamends that Governor of PA evacuate 5 mi. radius.
12.:07 Reg I Log E?A, Region III advised of evacuation recorrendation.
12:30 Reg I Log The NRC evacuation recommenda-tica is changed or is clarified as follows:
pregnant women and preschool children in the 5 mi. radius should be evacuated.
This recommendation to Gov.
PA - not public.
Dr. Langford of EPA is notified of this change.
1:00 SP Log Another conversation with FDAA re Governor's recommendation for President to call Nationai Security Council meeting at 1:30.
1.15 -
1:30 SP Log Calls to MD, Delaware, NY, NJ VA, W.VA Rad Health regarding Governor's recontendation.
1:25 Casr. Tel. Log Hendrie conference at White House followed by 1:30 p.m.
NSC meeting.
N 1:30 Reg I Another vehicle (2 H?s) departs for site.
2:00 Mossburg Denton +12 arrive by-Gossick Notes helicopter at site; Z:20 Mossburg' NRR Operations Center Gossick Notes established at nearby residence; notifications to President Carter and Governor Thornburch.
2:30 Reg I Director and Branch Chief plus 2 HPs cispatched by helic:pter g
. Date/ Time Source Activity (Abcut 3:20 Unverified Wayne Kerr (OS?) +5 arrive at site to assist IE Health Physics.
Ey this time, E3 NRC personnel are on site and in vicinity (Si IE, 4 SP, 3 FA, 25 NRR).
6:30 Press Release Press release "no imminent No. 79-67 danger of core melt; technical experts (Denton et al) en site" 3: 45 Reg I Log (Madden) acting as Administrative Officer reports the folicwing:
Trailer, manned by NRR (Denton) and the White House Communications Group is now behind the Observation Center and wired for use.
Additional Trailer by 2145 will be wired with 6 telephones.
Ecyce Grier is downtown in Harrisburg at a Press Ccnference w/Stello, Centon, Governor Thornburgh.
Air National Guard Unit at Harrisburg Int. Airport avail-able for assistance.
Saturday. Parch 31 Date/ Time Source Activity AM I?25 SP Leg Coordinating meeting held at Capital City Airport (EPA, DOE, PA Dept. of Environmental Rescurces, FDA, NRC).
3:50 SP Leg Telephone call from Eettis, Radiological Assistance Team at Co. and Pest at Capital City Air;crt; analytical equipment in airport hangar.
6:00 Reg I Lcg Oak Ricge man believes he can ri, a a )
use the Lease Parts Monitoring e{,.ie to tell the size of the bubble
,u in the vessel.
16 -
Cate/ Time Scurce Activity 5:25 SP Log Call frca P;. Civil Defense; status updatc.
About 9:00 Public Affairs Center activated at site; limited operation until April 1.
About 8:30 SP Lcg Trailer moves just uutside plant gate; NRR operations center in full force.
9:17 SP Log Call from HEW asking what their role would be if evacua-tion necessary; NRC says PA Civil Defense has lead; status update.
9:25 SP Log Call from CEQ; status report 9:20 SP Log Call from NY Rad Health Bureau; status report.
10:00 SP Log Call from Defense Civil Preparedness Agency; status report.
_P_M 12:00 SD Log Conversations with FDA-Sureau of 12:30 Radiological Health re supplies of potassium iodine.
s.
2:00 SP Log PA Rad Heal.th Dept. agrees to refer all calls relating to health matters to NRC.
3:26 Casr. Tel. Log Commission meets in Bethesda at Operations Center.
4:25 Cas r. Tel. Log Hend-ie and Governor confer via telephone on status.
5:00 SP Log NRC informed that Gcvernor, W.
Va. had activated State Radiological Assistance Team.
Ap
() * :0
- 1.. I
17 -
Cate/ Time Source Activity S;.,dav # oril 1
~
10:45 PN-67G NRC representative (Stello?)
at facility informed that sabotage attempt would be made during the night.
FBI, PA State Police and licensee notified.
1:30 SP Log SP calls DOE Co. and Center (they do not know where EPA people are); also calls PA Rad. Health; EPA lab is next door but no one is there.
8:13 SP Log SP calls PA Rad Health (DOE will collect all data and transmit results to NRC).
Mreting scheduleJ at 8:30 to set up coordination.
9:35 SP Log Contact established by Lubenau/Vaden at PA Rad. Health offices.
11:00 Reg I Log NRC Personnel on site (65 I&E; 27 NRR; 5 others).
FN-67H NRC establishes 37 TLD stations at distances from 1 to 12 miles from plant.
PN-67H All utilities with an operating B&W reactor are sent an NRC Bulletin to:
(1) provide information on TMI-2 incident (2) require a prcept review of their plant conditions, (3) tr.ke action to prevent such an incident.
NRC inspectors are being sent to each licensed S&W reactor to provide increased inspection coverage.
2:15 -
2:27 Reg I Log President Carter is on site in Unit 2 Centrol Rocm.
- 40 Gossick Notes NRC calls CCE/EOC to recuest cleanup of AUX Euilding..
General Public Ucilities 7.b r^\\**<
req ested help.
18 -
!';..dav Acril 2 C3 E s t e/ T i me.
Source Activity 3:25 Reg I Log Hg requests licensee to send sample of containment air (2330 sa.mple) to Bettis.
5:50 Reg I Log Phone link drcps out/HQ will try to re-establish ccaference call.
6:25 Reg I Log Phone link re-established F!i RIdnight Gossick notes Denton briefs Governor of PA.
s
(
_, a ~ 7 PRELIMINARY DESCRIPTION OF EVENTS AT THE THREE MILE ISLAND 2 FACILITY ACCIDENT The folicwing is a summary of the significant events that occurred at the Three Mile Islana No. 2 nuclear facility on March 28, 1979, and thereafter.
Attached is a detailed chronology of these events listed with the times they each occurred.
At about 4:00 am on March 23, 1979, the secondary (nonnuclear) cooling system of the Three Mile Island facility suffered a malfunction.
This system normally pumps water through the plant's steam generators where the water turns to steam which then flows to turn a turbine generatcr.
The water is then condensed back to water, is pumped by a condensate pump through a clean up system, through a feedwater pump, and finally back to the steam generators, and continually flows arou. a this loop.
A malfunction in the main feedwater system caused the feedwater pumps to turn off (trip), which in turn caused the turbine-generator to turn off and stop generating electricity.
Since the steam generators were not removing heat due to the stoppage of feedwater flow, the reactor coolant system pressure increased ani the pressurizer relief valve opened to reduce reactor pressure.
Immediately, the reactor tu ned off by the rapid insertion of the plant's control rods (scramr.ed) as designed and the nuclear chain reaction stopped leaving behind only residual, or decay, heat. These events all occurred within the first 30 seconds folicwing the event.
-* 1 ' O L9
\\(
ENCLOSURE 3
. Up to this point, this sequence is normal and the auxiliary feedwater system should startup and deliver secondary coolant to the plant's two steam generators to remov.e heat.
In addition, the pressurizer relief valve should close as reactor pressure decreases.
All three of the auxiliary feedwater pumps started but were unable to deliver flow because their flow paths were biccked by closed valves.
In addition, the pressurizer relief valve failed to close and therefore allowed the reactor coolant system pressure to continue to decrease.
As the reactor pressure reached a preset value (1600 psi), the piu s Emergency Core Cooling System (ECCS) started as designed and began to inject cold water into the reactor.
It is at this point that an indication of a rapicly rising pressurizer level apparently led the plant operators to teminate the ECCS flow. At this point the Three Mile Island incident nad been underway for 11-12 minutes.
Between about 1 and 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> into the transient, the operators turned off the four large pumps which circulate the reactor coolant through the reactor.
It is following this action that we believe the severe damage to the nuclear fuel began.
For the next several hours there was a very large temperature difference across the nuclear core indicating little flow of coolant through the core.
10'O?O During this several hour period, when severe fuel damage is occurring, primary coolant frem the reactor primary coolant system was being dumped onto the reactor containment floor from flow out of the pressurizer relief valve and through the drain tank.
This coolant, which contained radioactivity, was partially pumped from the reactor containment building floor to tanks in the auxiliary build',ag. The tanks overflowad parmiti.ing raaicactivity to be vented from the auxilia'ry building.
This situation lasted until about 9:00 am when the reactor containment was sealed (isolated).
During this time, from about 6:00 am until 8:00 pm, the licensee tried to depressurire the reactor coolant system sufficiently to be able to turn on the residual heat removal system.
Since his attempts failed, it was decided to repressurize the system.
/fter repressurization, one of the main "eactor coolant' pumps was restarted and flow through the reactor core was re-established.
Since feedwater was being provided to the steam generator, heat was being removed and the reactor system was slowly coolea.
Reactor cooling has essentially been in t'ais mode since that time.
9 4 - c, t
PRELIMINARY CHRONOLOGY OF THE MARCH 28, 1979 ACCIDENT AT THREE MILE ISLAND Time (accroxicate)
Discussion of Events Before 4:00 an TMI operator working on Feedwater System.
4:00 am The loss of all (main and auxiliary) feedwater flow occurred waile the reactor
'was operating at 98% power.
The transient was initiated by a loss of condensate pumps.
The turoine tripped.
3-6 sec later An electromatic relief valve opened to relieve pressure in the RCS* (2255 psi).
9-12 sec later The Reactor tripped on high RCS pressure (2355 psi) to terminate the nuclear reactor and reduce power generation to decay heat alone.
12-15 sec later The RCS pressure decayed to the point (2205 psi) where the relief valve should have reclosed.
The RCS continued to depressurize for about the next two hours.
15 sec later The temperature in the RCS hct. leg peaks at about 6100F with a pressure of about 2150 psi.
30 sec later The auxiliary feedwater pumps in both safety trains (1 turbine driven pump and 2 electrically driven pumps) were started and were running at pressure raady to inject water into the steam generators and remove the residual heat produced in the reactor core.
No water was injected since the discharge valves were closed.
- Throughout, RCS denotes "reactcr coolant system."
,a r e c)
L uj eJJ Time (acoroximate)
Discussion of Events 4:01 am The pressurizer level indication began to rise rapidly.
The steam generators, A and B, had icw levels of wate-and were drying out.
4:02 am The ECCS was initiated as the RCS pressure decreased to 1600 psi.
4:04-4:11 am The pressurizer level indication went offscale high and the operator manually tripped the first HPI pumos at about 4:04:30 and the second at about 4:10:30.
4:06 am Water in the RCS flashed to steam as the pressure bottoms out at 1350 psi.
The hog leg temperature was about 5850F.
4:07-4:08 am The P.eactor building sump pump came on.
4:08 am The operator opened the valves at the discharge of the auxiliary feedwater pump allowing water to be injected into the steam generators.
4:11-4:12 am The operator restarted the ECCS to inject water into the RCS to control pressurizer level.
4:11 am The pressurizer level indication comes back on scale.
4:lE am The RC Drain (Quench) tank ruoture disk blew at 190 psig due to continued discharge of the relief valve tnat had failed to open.
4:20-5:00 am The RCS parameters stabilized at a satur-ated condition of about 1015 psi and 5500F.
5:15 am The operator tripped both RC pumps in Loop B.
5:40 am The operator tripped both RC pumps in Loop A.
le 'I'O Time (accroximate)
Discussion of Events 5:45-6 am The reactor core began a heatup transient.
The RCS hot leg temperature went offscale at 620 degrees F within 14 minutes and the cold leg. temperature dropped to near the temperature of high pressure injec-tion water (150 degrees F).
6:20 am The failed open relief valve was isolated by the operator by closing a block valve.
The operator also isolated steam generator B to prevent leakage of radioactive secondary water from leaking S.B. tubes.
7:00 am The RCS pressure had increased to 2150 psi and the relief valve was ocened to relieve RCS pressure.
7:15 am A pressure spike of 5 psig occurred in the.lC drain tank due to steam from the relief valve.
7:45 am A pressure spike of 11 psig occurred in the RC drain tank and the pressure in the RCS was at 1750 psi.
9:00 am The pressure in containment peaked at 4.5 psig.
9:00-11:00 am The RCS pressure increased frca 1250 psi to 2100 psi.
11:30 am The operator opened the pressurizer relief valve to depressurize the RCS in an attempt to initiate RHR cooling at 400 psi.
12:00 am - 1:00 pm The RCS pressure decreased to about 500 psi and the core flooding tanks partially discharged.
The relief capacity was not sufficient to vent enough to reach 400 psi.
2:00 pm The pressure in the containment spikes at 28 psig causing containment sprays to be initiated.
The operator stopped the spray pumps after about 2 minutes of operation.
1Q C'?O Time (acoroximate)
Discussion of Events 5:30 pm The pressurizer relief valve was closed in order to repressurize the reactor coolant system.
5:30 - 8 pm The RCS pressure increased from 650 psi to 2300 psi.
8 pm RC pump in Loop A ws! started at which time the hot leg tei.4erature decreased to about 560 degrees F and the cold leg temperature increased to 400 degrees F, indicating flow tarough the steam gene ra to r.
Thereafter, the reactor was being cooled by reestablishing condenser vacuum and steaming to the condenser by steam generator A 5
-h the RCS cooled to about 280 degrees F and 1000 psi.
March 29 The RCS temperature and pressure was stablized at acout 280 degrees F and 840 to 1020 psi.
The maximum reading on the incore thermocouples was 612cF, but several were not with range for computer readouts (printing "?")
which was subsequently found to indicate greater than 700 degrees F.
March 30 The RCS temperature and pressure was stable at nearly 280 degt.:es F and between about 1000 to 1060 psi.
Several incore thermoccupies were beyond the range for computer readout, the maximum indicated reading was 659 degrees F.
The NRR staff estimated the bubble size in RCS to be about 1200 fc3 and requested the licensee to refine their calculation of the bubble size.
March 31 0
The RCS temperature and pressure remained stable at about 280 F and 1000 psi.
Slight drop in pressurizer level 251-191".
Temperatures in the core as measured from the incore thermocouples were gradually decreasing (maximum indicated about 5000F).
The hydrogen reccmbiner was in an operable status but additional shielding was needed and was being cbtained.
Two samples of containment atmosphere were analyzed which showed a hydrogen concentration of 1.7% and 1.0%.
Licensee calculated bubble size to be about 620 fto 0 875 psig.
g
-.. Aoril 1 No substantial change in RCS temperature and pressure Incore thermocouples continue to show decreased trend.
Licensee continued-hookup of hydrogen recombiners and addition of shielding.
Licensee calculated valves of bubble size varied.
Containment air samples indicate 2.3% hydrogen.
Acril 2 Reactor pressure stable at about '000 psi.
Incore tnermoccuoles continued to show a decrease with all measurements below 4750F.
Inlet and outlet 0
temperatures were still about 280 F.
One hydrogen recombiner was put in operation.
Analvsis indicated that the oxygen generation rate in reactor less than orig.aally estimated. Measurements indicated that the bubble was being significantly reduced.
Acril 3 Reactor pressure and temperature stable at 1000 psi and 2300F, rescectively.
Thermocouple readings analyzed-maximum 4770F, only 3 thermo,:ouples were 0
~
above 400 F.
Gas bubble size much reduced.
Containc.ent about 1.9%
One pressurizer level indicator failed.
Acril 4 Reactor pressure and temperature stable at 1000 psi and 280 F, respectively.
0 Thermocouple maximum temperature was 4660F.
Gas bubble size decreasing.
Vent valve on pressurizer intermittently opened and degassing contir.ues through letdcwn system.
April 5 Reactor pressure and temperature stable at 1000 psi and 280 F, respectively.
0 Maximum thermocouple reading is 462cF.
Pressurizer level responding normally to pressure changes indicating a completely full system.
Containment atmosphere indicates 2% hydrogen.
One recombiner operating, one in standby.
Pressurizer vented to containment about 15 minutes every 6-8 hours.
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. Acril 6 Reactor pressure stable at about 1000 psi and temperature about 2850F.
At approximately 1:25 pm, reactor coolant pump 1A tripped and reactor coolant pump 2A was started within about 2 minutes.
Shi ft in therro-couple readings. The three thermoccuoles previously reading about 4C00F are presently reading between 2850F and 3150F.
Central thermo-ccuole increased from 375cF to 4250F and is the only one reading about 0
400 F.
Containment measurements indicate about 2% hydrogen.
Pump-bacR system for pumping wasta gas decay tank voluma tc containment began.
Acril 7 0
Reactor oressure and temperature stable at about 1000 psi and 280 F, respectively.
At about 8 cm, the licensee bcgan to sicwly lower reactor system pressure.
The slow decrease will end when reactor pressure reaches 500 psi.
This is a step toward cold shutdcwn and includes degasi ?ication to prevent bubble famation as pressure and temperature decreases.
Hydrogen concentration in the containment is about 1.9%.
. gy v 3
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s
.- s GEhERIC CONSIDERATIONS
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...,...-1.,..-
i... c
.~__.o The felict.ing are the significant sequence of events that occurred at s
1" a.
The turbine tripped due to loss of main feedwater, b.
The reactor tripped, c.
The auxiliary feecwater pumps started but flow was not auxcmatically established, d.
The pressurizer relief valve apparently stuck open, e.
The high pressure injection was turned off, and f.
The reactor coolant pumps were turned off.
Our creliminary evaluation indicates that the incident may have been compounded by c.isleading indication of primary system water leval.
In addition, the consecuences of the incident were increased by the lack cf prompt automatic containmert isolation.
The initiating event, i.e., turbine trip and subsequent reactor trip.
are anticipated events in that they are expected to occur during the plant lifetime and the system is designed to resp nd safety.
In fact, cther Es.-l designed operating plants have experienced these kinds cf transients and have responded safely.
As a result of our preliminary evaluation of the TMI incident, however, we have preliminarily identified several human, design, and mechanical failures. They are all essentially relatec tc the loss of feedwater (item c abcve), the turr.ing off cf the F.ign pressure injecticn, (item e acove), and the turning off he reactar I'19,"8
\\.
ENCLOSURE 4
,. ccoiant pumps (item f above).
To ensure that these potential human, ce:i;n, t'id mechanical failures do nct result in a similar incident at other cperating facilities, we have directed (via IE Bulletins) cwners of facilities with S&W reacters to take several steps to ensure that safety margins are maintained.
In addition, we have formed an NRC Task Force to review in detail the causes of the TMI-2 incident and upon comoietion of these efforts will take subsepuent actions as appropriate.
The Task Force report will be completed abot.t the end of this month.
These NRC actions are also being taken at this time because of the prelimin2 y nature of our evaluation.
Certain additional information will be developed which will provide additional insights-into the actual causes and consequences of the various actions during the event.
At this time, however, our preliminary understanding of the event is sufficient to enable us to define the int ediate actions required of operating facilities with S&W reactors to prevent such an occurrence at these plants, and provide us with an adepuete basis to allow continued operation of these facilities.
First, the incident at TMI-2 was initiated by a loss of auxiliary feedwater following a turbine trip (item c above).
Since plants are ntt designed and evaluated for the complete loss of all feedwater, we have taken steps to ensure that the emercency feedwater system will be available to inject water under this situaticn.
At TF'.I-2, the block valves in the discharge lines from the auxiliary feedwater pumps were closed. We have required that operatina facilities with S&W 14 07D
. reactors ensure that these valves are always open by requesting their specific examination of these valve positions.
The position indication will be further verified by a full-time NP.C IE inspector at eac. of tnese plants.
Another generic aspect of this event and a significant centributor was the apparent sticking open of the electromatic valve on the pressurizer.
Licensees are being requested to examine their procedures such that operators are aware all valve positions, including the backup block valve to the relief valve, and have infomation available to permit its use.
The sticking open of the relief valve was a significant contributor to this event and would be considered an important event regardless of whsther auxiliary feedwater is available or not.
The second significant concern, which also has generic consicerations, ccncerns the turning off of the high pressure injection system.
In general, we have requested all cperators of plants to exercise extreme caution before turning off any safety system.
Specifically, we have taken steps to require operators to maintain high pressure injection for a minimum of 20 minutes if it is automatically actuated.
This occurs on icw reactor pressure (1000 psi) in the reactor.
We further require that high pressure injection bt. maintained until stable conditions are obtained.
We believe such actions may cause cperational inconveniences, but that they are not significant when compared to the gain to be made should a severe transient occur.
We also require in enO
4 tnat the LFI be maintained for 20 minutes following any icw pressure transients, including the case where a relief valve inadvertently opens and sticks open, to ensure pump coolant inventory.
Finally, we are requiring that if the reactor coolant pumps are in opcrttien when c severe feedwater transient might occur, they should be kept in operation if at all possible.
Furthermore, if possible, one shculd be kept running in each locp. This requirement provides an extra level of safety to cover a broad variety of transients.
In developinc this requirement, it was recogni:ed that coeration of the F. cps under certain ccnditions may damage the pumo due to cavitation, however, it is believed that such operation is appropriate to en:ure adequate response to a wide variety of transients.
The abcve mentioned staff requirements, in addition to our requirement that all licensees with S&W reactors review their designs, have been imposed to maintain and possibly increase marcins regarding their response to feedwater, and other, transients.
Such actions will, we believe, compensate for any remaining generic concerns regarding B&W reacters response to such transients.
Because the accident situation ap;sars to have been further ccmplicated by the containment not being isolated upon ECCS actuation, (in this case HPI), we have also taken steps to ensure that the containment is isolated to the extent possible given any particular event.
e '11. r - erli-
... The abcve menticned considerations have been directed tcwards 3&W reactors because they appear to be the ones most directly affected.
The described actions are intended primarily to be short term actions and may well be modified as a result of the NRC Task Ferce review of E&W reactor transients.
Certain of these interim actions may also later be shown to be applicable to other pressurized water reactors, i.e., those designed by Westinghouse and Combustion Engineecing.
These facilities have significant design differences.
Two significant cifferences between the B&W primary system desien and those of Westinghouse and Combustion Engineering are, first, the primary system water level for Westinghouse and Combustion Engineering are more directly measured.
The operators would, therefore, have had a more direct indication of primary system water level and would have been so influenced before stopping high pressure injection flow.
Seconoly, the steam generator volumes are larger for Westinghouse and Combustion Engineering plants, and therefore are less sensitive to feedwater transients allowing more time to cetect and correct any deficiencies in auxiliary feedwater flow.
Therefore, we have not required any actions of licensees with Westinghouse and Ccmbustion Engineering designed plants at this time, although.we have been sending them information ccpies of all actions recuired of owners of E&W reacters.
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