ML19224A882
| ML19224A882 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/23/1979 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Taylor J BABCOCK & WILCOX CO. |
| References | |
| NUDOCS 7906110028 | |
| Download: ML19224A882 (13) | |
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UNITED STATES E ' ' c,f(' %
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W ASHINGTON, D. C. 20555 V
MAY 2 31979 Mr. J ames H. Taylor Manager, Licensing Babcock & Wilcox Company P. O. Box 1260 Lynchburg, Virginia 24505
Dear Mr. Taylor:
SUBJECT:
ACRS RECOMMENDATIONS RELATING TO TMI-2 ACCIDENT In connection with its continuing review of the TMI-2 accident the Advisory Comittee on Reactor Safeguards (ACRS) has issued rnost recently two letters dated May 16, 1979 (see attached).
These letters restate and/or amplify a number of specific recomendations made by the Comittee in three earlier letters (date" April 7, April 18, and April 20,1979),
and contain a number of additioral new recomendations as well.
You viere requested by earlier ccrrespondence to provide the staff with a concise discussion and position on each of the ACRS recomendations relating to TMI-2 ir, the earlier letters. We are nnw requesting that you also respond to the additional recomendations contained in the May 16, 1979 letters.
For your convenience, we are enclosing a sumary (Enclosure 1) of the addi-tional recomendat. ions cor ;ained in the May 16, 1979 letter; please frame your responses in the format indicated in Enclosure 1.
We request that you provide your responses to these additional recomendations so that they will be received by the staff by May 29, rJ79.
If you require any clarificatic. of the matters discussed herein, please contact C. J. Heltenes, Jr.
Mr. Heltemes' telephone number is (301)-
492-7745.
Sincerely,
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u D. F. R6ss,' J r., Deputy Director Division of Project Management Office of Nuclear Reactor Regulation
Enclosure:
As stated 16'9 112 790611oogg.
ENCLOSURE 1 ADDITIONAL RECOMMENDATIONS RELATING TO TMI-2 ACCIDENT IN MAY 16, 1979 ACRS LETTERS A.
Interin Report No. 3 dated May 16, 1979 Reconnendation 1
- Examine operator qualifications, training and licensing, and requalification training and testing.
Recommendation 2 - Establisn formal procedures for the use of LER inforuation:
(a) in training supervisory and maintenance personnel (b) in licensing and requalification of plant operating personnel (c) in anticipating safety problems Recommendation 3 - Consider formal review of operating procedures for severe transients by inter-disciplinary team, and develop more star.dardized formats for such procedures.
Recommendation 4 - Re-examine comprehensively the adequacy of design, testing and maintenance of offsite and onsite AC and DC power supplies with emphasis on:
(a) failure modes & effects analyses (b) nore systematic testing of power system reliability (c) improved quality assurance and status monitoring of power supply systems Recommendation 5 - Make a detailed evaluation of current capability to withstand station blackout, f acluding:
(a ). examination of natural circulation capability under such circum. stances (b) continuing availability of components needed for long-term cooling under such circumstances (c) potential for improvement in capability to survive extended blackout Recomendation 6 - Examine a wide range of anomalous transients and degraded accidents which might lead to water hammer, with emphasis on:
(a) controlling or preventing such conditions (b) research to provide a better basis for control or prevention of such conditions 169 113
Recommendation 7 Plan and define NRC role in emergencies, including consideration of:
(a) assurance that forral emergency plans, procedures and organizations are in place (b) designation of emergency technical advisory teams (names and alternates)
(c) compilation of an inventory of equipment and materials needed in unusual conditions or situaticns Recommendation 8 - Review and revise within three months:
(a )
licensees' bases for obtaining offsite advice and assistance in emergencies from within and outside company (b) licensees' current bases for notifying and providing information to offsite authorities in emergencies Recommendation 9 - Examine the lessons learned at TMI-2, including con-sideration of the following:
(a) behavior, failure modes, survivability and other aspects of TMI-2 components and systems as part of the long-term recovery process (b) determine if design changes are necessary to facilitate decontamination and recovery of major nuclear power plant systems Reco rendation 10 - Expedite resolution of unresolved safety issues by the following means:
(a) suitable studies on a timely basis by licensees to augment NRC staff efforts (b) use of consultant and contractor support by NRC staff Recommendation 11 - Augment expeditously the NRC staff capability to deal with problems in reactor and fuel cycle chemistry in the following areas:
(a) behavior of PWR & BWR coolants and other materials under radiction conditions (b) generation, handling & disposal of radiolytic (or other) H at nuclear facilities (c) performance bf chemical additives in containment sprays (d) processing and disposal techniques for high and lor level radioactive wastes 169 114
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. (e) chemical operations in other parts _.of nuclear fuel cycle (f) chemical treatment operations involved in recovery, decontamination or decommissioning of nuclear facilities Reconsider whether or not use of the Single Failure Recommendation 12 -
Criterion establishes an appropriate level of reliability for reactor safety systems Recommendation 13 - With respect to safety research:
(a) consideration should be given to augmentation of the FY80 NRC safety research budget (b) consider orienting a larger part of the safety research tudget toward exploratory (as opposed to confirmatory) research Recommendation 14 - Perform design studies of a filtered venting or purging option for containments for possible use in the event of a serious accident Interim Report No. 2, dated fiay 16, 1979 Amplified many of the recommendations included in earlier ACRS letters 20, 1979, including ACRS views on dated April 7 April 18, and April relative priorities to be assigned a number of those earlier recorrendations.
(Address amplifications and suggested priority assignments as appropriate.)
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Pay 16,1979 Hcnorable Joseph M. Hendrie Chairman U. S. Nuclear Re:ulatory Commission Washington, DC 20555
Subject:
INTERIM REPORT NO. 2 ON THREE MILE ISI AND STLEAR STATICN LMT 2 Csar Dr. Hendrie:
During its 229th meeting May 10-12, 1979, the Advisory Committee on Re-actor Safeguards continued its review of the circumstances relatire to the recent accident St ihree Mile Island Nuclear Station Unit 2 (TNI-2).
Tne recom.mendations presented orally to the Commissioners on April 17, 1979 were reviewed by the full Committee and are rep 3ated in somewhat amplified form herein. A=plificatica of these items is resp:nsive to the reqJest of Actire NRC Chairman Victor Gilinsky dated April 18, 1979.
Natural Circulation - Procedures It is evident frca the exp3rience at TMI-2 that there was failure to es-tablish natural circulation of water in the primary syster and failure to recognize in a timely ranner that ratural circulation had rot been achieved.
Tne need for ratural circulation under certain circumstances is cce;non to all PGs.
Tne Coma.ittee recer= ends that procedures be developed by all op2rators of FWRs for initiating ratural circulation in a safe manner and for pro-vidire the op2rator with assurance that circulation has in fact been es-tablished.
Tnese procedures should cake into account the behavior of the systems under a variety of abnormal conditions.
As a first step, the NRC Staff should initiate irmediately a survey of op2ratirq procedures for achievirq ratural circulation, incit.dirg the case when offsite power is lost. At the same time, the op2:ators of all PG plants should be regJes ted to develop detailed aralyses of the be-hav.ior of their plants follcwire anticipated transients ard s,all breaks in the pri ary system, with appropriate censideration of potential ab-norral conditions, opnatcr errors and failures of equi 7.ent, n:wer sources, or instrumentation.
Tnera analyses ara nec?s m y for the e
169 116
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Y Honorable Joseph M. Hendrie.Kay 16, 1979 development of suitable operating procedures.
The review and e/alu-tion of these analyses by the NRC Staff should receive a priority consistent with the priority being given to cha jes in operating procedures.
Natural Circulation - Pressurizer Heaters The use of natural circulation for decay heat removal. following an accident in a PWR nocc: ally requires the maintenance of a suitable over-pressure on the reactor coolant system in order to prevent the genera-tien of steam which can imcede circulatien.
For many transients, r.ain-tenance of this overpressure is best acccmplished by use of the pres-suricer heate rs.
Although the pressurizer heaters at TMI-2 continued to receive power f rom offsite sources caring the entire accident, the availability of offsite pcwer cannot be assured for all transients or accidents during which, or following which, natural circulation cast be established.
The Cocaittee recoc= ends that the NRC Staff initiate i:-ediately a survey of all Pes licensed for cperation to determine whether the pressuricer heaters are new or can be supplied with pcwer from qualified ensite sources with suitable redundancy.
Nctural circulation - Saturation Conditions The plant operators should be informed adequately at all tices of those conditicas in the reactor coolant system that might affect their capa-bility to place the system in the natural circulation mode or to sustain it in such a mode.
Information indicating that coolant pressure is ap-preaching the saturation pressure corresponding to the core exit temper-ature would be especially useful, since an impendirg loss of overpressure would signal-to the operator a potential loss of natural circulation.
This informatica can be derived frem available pressurizer pressure and hot leg temperature measurements, in conjuction with conventional steam tables.
Tne Cemittee recc= ends that information for detecting an aporoach to saturation pressure be displayed to the operator in a suitable form at all ti Since there may be several equally acceptable means of information, there is no need for the NRC Staff to as-prcyidia; riority to the development of prescriptive requitecents sign a hi3 for s;ch di plays.
Mcwever, a reasonably early request that licensees and ve.dcrs ccasider and ccoment on the need f or sJch a display would be aggrcpriate.
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Honorable Joseph M. Hendrie May 16, 1979 Core Exit Therrocouples The NRC Staff should request licensees and vendors to consider whether the core exit temperature measurements might be utilized, where avail-able, to provide additional indication regarding natural circulation or the status of the core.
For the latter purpose, it is recommended that the full temperature range of the core exit thermocouples be utilized.
At TMI-2, the temperatures displayed and recorded did not include the full range of the thermocouples.
The Committee believes it.would be apprcpriate for the NRC Staff to re-quest licensees and vendors to consider and comment on this reccamenda-tion.
This request should be made as soon as convenient and the time allowed for responses should be such as not to degrade responses on higher priority ratters.
Plant changes that might result eventually from consideraticn of this recommendation would not at this time seem to require a high priority.
Instrurentation to Follcw the Course of an Accident The ability to follow and predict the course of an accident is essential for its mitigatien and for the provision of credible and reliable pre-dictions of potential offsite consequences.
Instrumentation to follcw the course of an accident in power reactors of all types has long been a concern of the ACRS, is the subject of Regulatory Guide 1.97 (which has not yet been implemented on an operating plant), and is the subject of an NRC Staff Task Action Plan for the resolution of generic issues.
The Committee believes that the pasitions of Regulatory Guide 1.97 should be reviewed, and redefined as necessary, and that the ' Task Action Plan should be reexamined, as soon as manpower is available.
The les-sons learned from TMI-2 should be the bases for these reviews.
For ex-ample, improved sampling procedures under accident conditions should be considered.
Althcogh review and reexamination of existing criteria may take some time, the studies completed to date, together with the understanding gained from the accident at TMI-2, should prcvide suf ficient basis for planned and a::rrepriately phased actions.
The Committee b?11 eves that the installaticn of impreved insta=entation on cparating reactors of all tyces should be undersay within one year.
169 118 p
H ncrable Joseph M. Hendrie May 16, 1979 Reactor Safety Research The ACRS recomends that safety research en the behavior of ligh:. water reactors during anomalou.s transients be initiated as soon as possible and be assigned a high priority.
nie Acos would expect to see plans and propesals within about three cenths, preliminary results within an additienal six renths, and more ecmprehensive results within a year.
Of particular interest would be the develep ent of the capability tc simu'. ate a wide range cf p:stulated transient er accident c nditicas, including various abner,a1 or 1:w probability rechanical failures, ele:-
trical failures, or hc.an errors, in order to gain increased insight into measures tqat can be,taken to i.Torove safety.
Tne new prceram of research to improve reactor safety has been initiated only recer tly, and then only en a relatively s all scale.
Tne Cc=ittee reiterates its previcus recomendations that this prccram be parsued and its expansien sought by the Comission with a greater sense of urgency.
Status Monitorine Although the closed auxiliary feedwater system va'ves may not have con-tributed directly or significantly to the core damage or environmental releases at D'.!-2, the patentially much more severe consq2ences of un--
availability of engineered safety features in plants of any type is of concern and deserving of attention.
Status monitoring not dependent chiefly on administrative control, and thus possibly less subject to hu-man error, might help assure the availability of essentici features.
A req 2est should be made within the next few renths that licensees con--
sider additienal status monitorirs; of various engineered safety features and their supporting services.
'E.e raC Staff should begin studies on the advantages and disadvantages of such ronitoring co about the same time scale. Responses frcm licensees should be expected in about one year, at which time the lac Staff should be in a position to review and evalu-ate them.
Tne. Comittee recognices that some of the reccmend+d actions in this report have already been taken by the lac Staff.
S'ncerely, 4 (A )
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Kay 16, 1979 Honorable Joseph M. Hendrie Chairman U. S. Nuclear Regulatory Ccc=ission Washington, EC 20555
Subject:
I??!'ER".M REPORT No. 3 CN TdRIE MILE ISUAD ?OCLDR STATION UNIT 2
Dear Dr. Hendrie:
During its 229th meeting, May 10-12, 1979, the Advisory Ccemittee on Reactor Safeguards continued its review of the recent accident at Three Mile Island Naclear Station Unit 2 ('mI-2), includirg implications drawn from the cccurrence of this accident. The Committee has several addi-tivnal reco m.endations to make at this time.
Reacter Fressure Vessel Level Indication
'Ihe Cc =ittee believes that it would be prudent to consider expeditiously the provision of instrumentation that will provide an unar.biguous indica-tien.of the level of fluid in the reactor vessel.
We suggest that licens-ees of all pressuriced water reactors be requested to submit design pro-Tnis would assure posals and schedules for ac:cmplishire this action.
the timely availability of reviewed designs if the Staf f ongeirg studies Tae Com.mittee should indicate that early implementation is reqJired.
believes that as a minimum, the level indication should range frem the botten of the hot leg piping to the reactor vessel flarge area.
Ocerator Trainim and Qualification The ?GC Staff should examine operator qualifications, training, and li-Consideration should be censirs tu du ermine @at changes are needed.
given to educetional background, to training rethods, and to content of Attentien should also be civen to testing rathods, the training program.
with specific concern for the ability of the testinc methcds to predict operator cacability.
Examination of licensirg.crocedures should deter-mine whether they. are respcnsive to new infor ation that is developed a'ccut plant or operator perfor rance.
Ef fo t should also be made to cete rine -tether resu'_ 3 of exa-equalificatica tr DUPL,1CATE DOCUMENT ator ability.
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