ML19224A880
| ML19224A880 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/23/1979 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Nechodom W SIEMENS POWER CORP. (FORMERLY SIEMENS NUCLEAR POWER |
| References | |
| NUDOCS 7906110018 | |
| Download: ML19224A880 (13) | |
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WASHING TON, D. C. 20555
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%,.....f MAY 2 31979 Mr. Warren Nechodon Manager, Licensing & Compliance Exxon Nuclear Conpany, Inc.
2101 Horn Rapids Road Richland, Washington 99352
Dear Mr. Nechodom:
SUBJECT:
ACRS RECOMMENDATIONS RELATING TO TMI-2 ACCIDENT In connection with its continuing review of the TMI-2 accident, the Advisory Comaittee 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 recommendations made by the Comittee in three earlier letters (dated April 7, April 18, and April 20,1979),
and contain a number of additional new reccmendations 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.
to the additional recomendations contained in the MayWe are now requesti 16, 1979 letters.
For your convenience, we are enclosing a summary (Enclosure 1) of the addi-tional recomendations contained in the May 16, 1979 letter; please frame your respcases in the format indicated in Enclosure 1.
We request that you provide your responses to these additional recommendations so that they will be received by the staf f by May 29, 1979.
If you require any clarification of the matters discussed herein, please contact C. J. Heltenes, Jr.
492-7745.
Mr. Heltemes' telephone nunber is (301)-
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D. F. Ross, Jr., Dcputy Director Division of Project Managenent Office of Nuclear Reactor Regulation
Enclosure:
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ENCLOSURE 1 ADDITIONAL RECCMMENDATIGNS RELATING TO TMI-2 ACCIDENT IN MAY 16, 1979 ACRS LETTERS A.
Interim Report No. 3 dated May 16, 1979 Recommendation 1
- Examine operator qualifications, training and licensing, and requalification training and testing.
Establish formal procedures for the use of LER Recommendation 2 in fo nnation:
(a) in training supervisory and maintenance personnel (b) in licensing and requalification of plant operating personnel (c) in anticipating safety prc;' ems Recommendation 3 - Consider formal review of operating procedures for severe transients by inter-disciplinary team, and develop more standardized 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) rore 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, including:
(_al 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 Recommendation 6 - Examine a wide range of anomalous transients and degraded accidents which night lead to water hammer, with emphasis on:
(a) controlling or preventing such conditicns (b) research to provide a better basis for control or prevention of such conditions 169 095
T Recommendation 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 and alternates)
(c) compilation of an inventory of equipment and materials needed in unusual conditions or situations Recorrendation 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 decontaminatior and recovery of majer nuclear power plant systems Recomendation 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 consul tant and contractor support by NRC staff Recomendation 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 radiation conditions (b) generation, handling & disposal of radiolytic (or other) H at nuclear facilities (c) perfornance bf chemical additives in containmer t sprays
(.d) processing and disposal techniques for high ant low level radioactive wastes 169 096
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. (e) chemical operations in other part,s_ 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 Failurc Recommendation 12 -
Criterion establishes an appropriate level of reliability for reactor safety systems Racommendation 13 - With respect to safety research:
(a) consideration should be given to augmentation of the FY80 fGC safety research budget (b) consider orienting a larger part of the safety research budget.oward 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 to. 2, dated May 16, 1979 Amplified many of the recommendations included in earlier ACRS letters dated April 7, Aprii 18, and April 20, 1979, including ACRS views on relative priorities to be assigned a number of those earlier recontendatior.
(Address amplifications and suggested priority assignments as apprcpriate.)
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5 UNITEL STATES f K 4-i NUCLEAR REGULATORY COMMISSION 7t h7' f
ADVISORY COMMITTEE ON REACTOR SAFEGUAROS WASHING ton. D. C. 2':555 p
May 16, 1979 Honorable Joseph M. Hendrie Chairran U. S. Nuclear Regulatog Commission Washir>gton, IC 20555
Subject:
IEERIM FIPCTC NO. 2 CN T 'IE MILE IS!.ANO N'XLUR STATICN UNIT 2
Dear Dr. Hen:
- -ie:
During '
9th meeting.May 10-12, 1979, the Advisory Co mittee on Re-actor neguards continued its review of the circu-stances relatirg to the recent accidenc at 'Ihree Mi)e Island Nuclear Station Unit 2 (NI-2).
Tne. recom.mendations presented orally to the Cc=issioners on April 17, 1979 were reviewed by the full Committee and are rep =ated in somewhat amplified form herein. Amplification of these items is responsive to the recuest of Acting ?GC Chairr.an Victor Gilinsky dated April IS,1979.
Natural Circulation - Procedures It is evident from the exparience at NI-2 that there was failure to es-tablish natural circulation of water in the prir.ary syster and f ailure to reccgnize in a timely ranner that ratural circulation h.ad rot been achieved. Tne need for natural circulation under certain circu.. stances is ccamon to all PARS.
Tne Com.r.ittee reco= ends that procedures be developad by all operators of PnRs for initiating ratural circulation in a safe manner and for pro-viding the oparator with assurance that circulation has in fact been es-tablished. Tnese procedures should take into account the behavior of the systems under a variety of abnormal conditions.
As a first step, the tac Staff should initiate i.r. mediately a survey of op2 rating procedures for achievirq ratural circulation, includirg the case when offsite power is lost. At the sar.e time, the operators of all PdR plants should be recuested to develop detailed aralyses of the b2-hav.f or of their plants follcwing anticipated transients and small breaks in the privary system, with appropriate cons.deration of potential ab-normal ccnditions, op'rator erro.s and failures of e~uipent, ?:wer sources, or instrumentation. Toese analyses are necessary for the 169 098 n.-%
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Honorable Joseph M. Hendrie yay 16,1979 develo,: cent of suitable operatiry procedures.
The review and evaluation of these ar.alyses by the NRC 5taff should receive a priority consistent
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with the priority being given to changes in operating procedures.
Natural Circulation - Pressurizer Heaters The use of natural circulation for decay heat removal. following an accident in a PWR normally re rires the maintenance of a suitable over-pressure on the reactor coola:
system in order to prevent the genera-tien of stern which can impede circulatien.
For marf transients, main-tenance of this overpressure is best accomplished by use of the pres-surizer heate rs.
Although the pressurizer heaters at TMI-2 continued to receive power f rom of fsite sources turirs the entire accident, the availability of offsite power cannot be assured for all transients or accidents during which, or following which, natural circulation mast be established.
The Cormittee recommends that the NRC Staff initiate irmdiately a survey of all P4as licensed for operation to determine whether the pressurizer heaters are now or can be supplied with power from qualified onsite sources with suitable redundancy.
Natural Circulation - Satur3. ion Ccnditiens The plant peretnrs should be informed adequately at all tices of those conditions 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 impending loss of overpressure would signal to the operator a potential loss of natural circulation.
Tnis information can be derived from available pressurizer pressure and hot leg temperature measurements, in conjuctica with conventional steam tables.
The Comittee recemends that information fcr detecting an approach to saturation pressure be displayed to the operator in a suitable form at all times.
Since there may be several equally acceptable means of providing this information, there is no need for the NRC Staff to as-sign a high priority to the development of prescriptive requirements fer such displays.
However, a reasonably early request that licensees and vendors consider and ccoment on the need for sJch a display ould be appropriate.
169 099 3~.
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Honorable Joseph M. Hendrie May 16,1979
--Core Exit Therrocoucles 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 parpose, it is receccended that the full temperature range of the core exit thermocouples be utilized.
i At TMI-2, the temperatures displayed and recorded did not include the full range of the thermocouples.
The Comrittee believes it / ould be appropriate for the NRC Staff to re-cuest licensees and vendors to consider and comment on this recommenda-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 matters.
Plant changes that might result eventually from consideration of this recommendation would not at this time seem to require a high priority.
Instrurentation to Follow 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 follow the course of an accident in power reactors of all types has long been a ccncern 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 Comnittee 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 manpcwer is available. The les-sons learned from TMI-2 should be the bases for these revices.
For ex-ample, improved sampling procedures under accident conditions should be considered.
Althcogh review and reexamination of existiny criteria rey take some time, the studies completed to date, together with the understanding gained from the accident at TMI-2, should provide sufficient basis for planned and appropriately phased actions. 'Ite Ccr,ittee believes that the installation of improved instrumentation on op3 rating reactors of all types should be u. der. cay within cne year.
i69 100 p
1 H:norable Joseph M. Her.drie Fay 16,1979 Reactor Safety Research The ACRS reccmends that safety research on the behavior of light-water reactors durir,g anomalous transients be initiated as soen as pessible and be assigned a high priority.
me AC ts would expect to see plans and pro,resals within atout three months, preliminary results within an additional six renths, and core ccmprehensive results within a year.
Of carticular interest would be the develop ent of the capability to simulate a wide range of p:stulated transient er ac:ide..: c:nditiens, includi.g various abner al or low probability mechanical failures, elec-trical failures, or hr.an errors, in order to gain increased insight into measures that can be.taken to imo. rove safety.
e The new program of research to improve reactor safety has been initiated caly recently, and then only on a relatively s.all scale.
Tne Co=ittee reiterates its previous reco=endatiens that this program be prsued and its expansion s:ught by the Cc=ission with a greater sense of urgency.
Status Monit:rinc 11thcugh the closed auxiliary feed. cater system valves may net have con-tricated cirectly or significantly to the core da.. age or envircr. mental releases at n'.!-2, the pctentially much more severe consegaences of un-availability of engineered safety features in plants of any type is of concern and deserving of attentien.
Status menitoring not dep2ndent chiefly on a:i-inistrative control, and thus pcssibly les.s sabject to hu-
.aan error, might help assure the availability of essential features.
A request should be made within the next few cenths that licensees cen-cide: additieral rtatus monitorirs of varicus engineered safety features and their supporting services. De EC Staff should begin studies cn the advantages and disadvantaces of such ronitorirq cc. about the sa.me time sca.e.
Responses from licensees should be expected in about one year, at which time the MC Staff should be in a pcsition to review and evalu-ate them.
The. Comittee recognices that some of the reccamenced actions in this re.mrt have alreadv. been taken by the EC Staff.
S'ncerely,
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May 16,1979 Honorable Joseph M. Hendrie Chairman U. S. Nuclear Regulatory Commission Washington, EC 20555
Subject:
INTERI.M REPORT SO. 3 CN THREE MILE IS*J.C KJCLOR STATION Li:T 2 Cear Dr. Hendrie:
During its 229th meeting, May 10-12, 1979, the Advisory Ccemittee on Reactor Safeguards continued its review of the recent accident at Tnree Mile Island S.: clear Station Unit 2 GMI-2), including implications drawn f rca the occurrence of this accident. The Ccccittee has several addi-tional rece nendations to make at this time.
Reactor Pressure vessel Level Indicatica The Com.Tittee believes that it would be prudent to censider expeditiously the previsien of instrumentation that will provide an una.biguous indica-tien,cf the level of fluid in the reacter vessel.
We saggest that licens-ees of all pressoriced water reactors be recuested to submit design pre-Tnis would assure pesals~ and schedules for accomplishirg this actien.
the timely availability of reviewed designs if the Staf f ongoi g studies Tae Committee should indicate that carly implementation is recuired.
believes that as a minimum, the level indication should rarse frco the rx>ttom of the hot leg piping to the reactor vessel flange area.
Crerator Traininc and Qualificaticn The NRC Staff should examine operator cualifications, training, and li-censing to determine ' hat charges are needed.
Consideration should be given to educational background, to training r,2thods, and to content of Attentien should also 62 given to testing rethods, the training prcgram.
with specific concarn for the ability of the testinc methcds to predict c.erator capability.
Examination of licensing procedures shculd deter-c mine whether they. are rescensive to new inferration that is develop:4 about plant or operator perforrance.
Effort should also be made to cete:mine -tether results of examir
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