ML19224A881
| ML19224A881 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/23/1979 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Anderson T WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP. |
| References | |
| NUDOCS 7906110025 | |
| Download: ML19224A881 (13) | |
Text
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5 pH REG f
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MAY 2 3 Ing Mr. Tom M. Anderson, Manager Nuclear Safety Department Westinghouse Electric Corporation P. O. Box 355 Pittsburgh, Pennsylvania 15230
Dear Mr. Anderson:
SUBJ ECT: 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 most 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 (dated April 7, April 18, and April 20,1979),
and contain a number of additional new recomendations as well.
You were requested by earlier correspondence to provide the staff with a concise discussion and position on each of the ACRS recommendations relating to TMI-2 in the earlier letters. We are now requesting that you also respond to the additional recomendations contained in the May 16, 1979 letters.
For your convenience, we are enclosing a summary (Enclosure 1) of the addi-tional recommendations contained 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, 1979.
If you require any clarification of the matters discussed herein, please contact C. J. Heltemes, Jr.
Mr. Heltemes' telephone number is (301)-
492-7745.
Sincerely, k,
lf D.N. Ross, J r., Depu+.y Director Division of Project Management Office of Nuclear Reactor Regulation
Enclosure:
As stated 169 103 79061100 M
e ENCLOSURE l_
ADDITIONAL RECOMMENDATIONS RE'.ATING TO TMI-2 ACCIDENT IN MAY 16, 1979 ACRS LETTERS _
A.
Interim Report No. 3 dated May 16, 1979 Recommendation 1 Examine operator quali fications, training and licensing, and requalification training and testing.
Reconmendation 2 - Establish formal procedures for the use of LER in fo nnation:
(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 standardized formats for such procedures, Reco=endation 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) rore systematic testing of power system reliability (c) improved quality assurance and status monitoring of power supply systems Recomendation 5 - Make a detailed evaluaticn of current capability to withstand station blackout, including:
(.a ) examination of natural circulation capability under such circumstances (b) continuing availability of components needed for long-term cooling under such circumstances (c) potential for improvement in capability to survive extended blackout Reccmmendation 6 - Examine a wide range of ancmalous 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
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-2 Reconmendation 7 Plan and define NRC role in emergencies, including consideration of:
(a' assurance that formal emergency plans, procedures and organizations are in place (b) designation of emergency technical advisory teams (names ard alternates)
(c) compilation of an inventory of equipment and materials needad in unusual conditions or situations Reconrendation 8 - Review and revise within three months:
(a) licensees' bases for obtaining offsite advice and assistante in emergencies from within and outside company (b) licensees' current bases for notifying and providing information to offsite authorities in emergencies Examine the lessons learned at TMI-2, including con-Recommendation 9 sideration of the following:
(a) behavior, failure modes, sur/ivability 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 Recorrendation 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 Recccmendation 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 coo: ants and other raterials under radiation conditions (b) generation, handling & disposal of radiolytic (or other) H at nuclem facilities (c) performance $f chemical additives in containment sprays (d) processing and disposal techniques for high and low level ra'dioactive wastes 169 105
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, (e) chtmical 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) consideraticn 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 Perform design studies of a filtered venting or Recommendation 14 -
purging option for containments for possible use in the event of a serious accident Interim Report No. 2, dated l'.ay 16, 1979 Amplified many of the recommendations included 'n earlier ACRS letters 20, 1979, ir.cluding ACRS views on dated April 7, April 18, and April relative priorities to be assigned a number of those earlier reconnendations.
(Address amplifications and suggested priority assignments as appropriate.)
169 106
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UNITED STATES fh 4-r l ;
NUCLEAR REGULATORY COMMISSION s b, O ADVISORY COMMITTEE ON REACTOR SAFEGUARDS t M,@/e 'l r
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May 16,1979 Honorable Joseph M. Hendrie Chairran U. S. Nuclear Ryulatory Commission Washington, IC 20555
Subject:
INTERIM FIFGT NO. 2 CN Tr3EE MILE ISLRC NTLElR STATICN UNIT 2 E-ar Dr. Hendrie:
Durire its 229th neeting May 10-12, 1979, the Advisory Co mittee on Re-actor Safeguards continued its review of the circu-stances relatia; to the recent accident at Three Mile Island Nuclear Station Unit 2 (mI-2).
Tne recommendations presented orally to the Commissioners on April 17, 1979 were reviewed by the full Committee and are repeated in some.6at amplified form herein. A plificatien cf these item.s is resp:nsive to the regacst of Acting ?GC Chairran Victor Gilinsky dated April 18, 1973.
Natural Circulation - Procedures It is evident frem the exp2rience at TMI-2 that there was failure to es-tablish ' natural circulation of water in the prir.ary syster and failure to reccgnize in a timely reanner that ratural circulatien had rot been achieved.
Tne need for ratural circulation under certain circa stances is cccenon to all Pes.
The Com.nittee recommends that procedures be developed by all_ o,cerators of Pets for initiating ratural circulation in a safe raanner and for pro-vidirs the operator with assurance that circulation has in fact been es-tablished. These procedures should take into account the behavior of the systems under a variety of abnormal conditiens.
As a first scep, the tac Staff should initiate ir:nediately a survey of oparatirq procedures for achieving natural circulation, includirs the case when offsite power is lost. At the same time, the operators of all P.G plants should be req.2ested to develop detai1~i aralyses of the be-hav.f or of their plants follcwir.g anticipated transients and call breaks in the prirary system, with appropriate consideration of potential ab-normal conditiens, op2 ater errors and failures of equirent, ccwe r sources, or instrumentatica. Tnese analyses ara nec2csary for t'.e 169 107 A
Honorable Joseph M. Hendrie J'ay 16,1979 development of suitable operating procedures.
De review and evaluation of these analyses by the NRC Staf f should receive a priority consistent
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with the priority being given to changes in operatin: procedures.
Natural Circulation - Pressurizer Heaters The use of natural circulation for decay heat removal. following an accident in a PWR normally requires the mainten:nce of a suitable ever-pressure on the reactor coolant system in order to prevent the genera-tien of steam which can impede circulatien.
For mar; transic.:ts, r.ain-tenance of this everpressure is best accomplished by use of the pres-surizer beate rs.
Althou:h the pressurizer heaters at TMI-2 centinued to receive power f rem of fsite sources curing the entire accident, the availability of offsite power cannot be assured for all transients or accidents during which, er following which, natural circulation must be established.
The Comaittee recorrends that the NRC Staff initiate in ediately a survey of all Fes licensed for operation to determine whether the pressurizer heaters are now or can be supplied with power from qualified onsite sources with suitable redandancy.
Natural Circulation - Saturation Conditiens The plant cperators should be informed adequately at all tires of those conditions in the reactor coolant system that might affect their capa-bility to place the system in the ratural circulation node or to sustain it in such a mode.
Information indicating that coolant pressure is ap-preaching the saturation pressure corresponding to the core exit terper-atore would be especially useful, since an impending loss of overpressure would signal to the operator a potential 1 css of natural circulation.
Tni: inforration can be derived from available pressurizer pressure and hot leg temperature measurements, in conjuctica with conventional stea.m tables.
Tha Committco reccmmends that information for detecting an approach to saturation pressure be displayed to the operator in a s;itable form at all times.
Since there may be several e7; ally acceptable means of preyidia? this information, there is no need for the NRC Staff to as-sign a high priority to the developcent of prescriptive requirements f or s;ch displays. However, a reasonably early request that licensees and vendors consider and comment en the need for s; h a display would be apv::E-iate.
169 108 3.
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Honorable Joseph M. Hendrie May 16,1979 Core Exit Therroccuples The NRC Staff should request licensees and vendors to consider whether the core exit temperature neasurements 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 recoc. ended that the full temperature range of the core exit thermocot,les be utilized.
At TMI-2, the terperatures displayed and recorced did not include the full range of the thermocouples.
The Committee believes it vould be appropriate for the N30 Staff to re-cuest licensees and venders to consicer and come ent on this recc menda-tion.
This request should be made as soon as convenient and the tice allowed for responsea should be such as not to degrade respensen on hicher priority matters.
Plant changes that might result eventually from consideration of this recommendation would not at this tima seem to require a high priority.
Instrunentation to Follow the Course of an Accident The ability to follow and predict the ecurse of an accident is essential for its mitigation and for the provision of credible and reliable pre-dictions of potential offsite consequences.
Instrumentation to follow-the course of an accident in power reactors of all types has lor:; been a concern of the ACRS, is the subject of Tegulatory Guide 1.97 ('Sich 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 positions of F.egulatory Guide 1.97 should be reviewed, and redefined as necessary, and that the ' Task Action Plan should be reexamined, as soon as manpo'-er 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.
Althcagh review and reexamination of existing criteria ray take some time, the studies completed to date, tocether with the understanding cained frem the accident at TiI-2, should provide sufficient basis for planned and appropriately phased actions.
Tne Cocnittee believes that the installation of im,aroved instrumentatien on cperating reactors of all types should be undereay within one year.
169 109
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H:ncrable Joseph M. Fendrie May 16, 1979 Reactor Safety Research The ACRS recomnands that safety reseerch en the behavior of light-eater reactors during anomalous transients be initiated as seen as pessible and be assigned a high priority.
The ACRS would ex:ect to see plans and propesals within about three mcnths, prelimir.ary results within an additienal six months, and rcre ecmprehensive results within a year.
Cf particular interest would be the develepnent of the capability to simulate a wide range of postulated transient er ac:! dent c nditicns, including various abnerral or Icw prcbability rechanical failures, ele:-
trical failures, or human errors, in order to gain increased insight into reasures that can be,takcn to improve safety.
The new program of research to improve reactor safety has been initiated only recently, and then caly on a relatively small scale.
The Ccmmittee reiterates its previous recommendations that this program be pnsued and its ex cnsion sought bv the Cem.Tission with a greater sanse of urcency.
e Status Monitoring Although the c1csed auxiliary feedweter system valves may not have con-tributed directly or significantly to the core dama:e er envircr. mental releases at TC-2, the potentially much more severe consr7uen:es of un-availabilitv of engineered safety features in plants of anv t.v e is of concern and deserving of attentien.
Status monitoring not dep2ndent chiefly en administrative centrol, and thus p:ssib1v less subject to hu-a man error, might help assure the availability of essential feate:es.
A reg;est should be made within the next few acnths that licensees cen-sider additional status monitorirc. of varicus ena.ineered safety. features and their supporting services.
The NRC Staff should begin studies on the advantages and disadvantages of such ronitoring on about the same time scale. Respcases from licensees should be expected in about one year, at which time the NRC Staff should be in a position to review and evalu-ate them.
The. committee recognizes thet some of the recenmended actions in this report have already been taken by the NFC Staf f.
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ADVISORY COMMITTEE CN RE A TOR SAFEGUARDS
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~, >' ]-N WASHINC TCN. D. C. 20555 May 16,1979 Honorable Jeseph M. Hendrie Chairman U. S. Nuclear Regulatory Comission Washington, EC 20555
Subject:
IhTE;IM REPC:.T SJ. 3 CN 29IE MILE IS'J.C hDCLOR STATICN
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Dear Cr. Hendrie:
During its 229th meeting, May 10-12, 1979, the Advisory Cce.mittee on Reactor Safc-guards centinued its review of the recent accident at 'inree Mile Island Naclear Statien Unit 2 (241-2), including implications drawn f rom the cccurrence of this accident. The Corr.ittee has several addi-tional rec =endations to make at this time.
Reacter Pressure Vessel Level Indicatien The Cc=ittee believes that it would be prudent to consider expediticusly the provision of instre. entation that will provide an una.bicuous indica-tien of the level cf fluid in the reactor vessel. We s;ggest that licens-ees of all pressoriced water reactors be requested to submit design pro-Tnis w:uld assure pesals and schedules for accomplishirg this acticn.
the timely availability of reviewed designs if the Staf f cngeirg studies The Cor.mittee should indicate that carly implementation is regaired.
believes that as a minimum, the level indication should rarse from the totten of the hot leg piping to the reactor vessel flange area.
Crerator Traininc and Qualification The NRC Staff should examine cparator qualifications, trainirs, and li-censing to determine dat changes are needed. Consideration should be given to e-5ucational background, to training rathods, and to centent of Attentien should also te given to testing r.ethods, the training program.
with specific concern for the ability of the testinc methcds to predict cparator capability.
Examination of licensirq procedures should deter-mine whether they. are respcnsive to new infor:.ation that is develop =d about plant or op3 rator pe r for.T.2nce.
Effort should also be made to
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