ML19224A883
| ML19224A883 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 05/23/1979 |
| From: | Ross D Office of Nuclear Reactor Regulation |
| To: | Scherer A ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY |
| References | |
| TAC-8162, NUDOCS 7906110035 | |
| Download: ML19224A883 (13) | |
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NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C 20555
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MAY 2 3 lua Mr. A. E. Scherer, Licensing Manager Combustion Engineering, Incorporated 1000 Prospect Hill Road Windsor, Connecticut 06095
Dear Mr. Scherer:
SUBJECT:
ACRS RECOMMENDATIONS RELATING TO TMI-2 ACCIDENT In connection with its continuing review of the TMJ-2 accident, the Advisory Committee 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 reconmendations made by the Conmittee in three earlier letters (dated April 7, April 18, and April 20,1979),
and contain a number of additional new recommendations 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 recommendations contained in the fiay 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 formt indicated in Enclosure 1.
We request that you provide your responses to these additional recommendatior.s so that. ; hey 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, b[-
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D. F. pros,s,, Jr., Deputy Director Division of Project Management Office of Nuclear Reactor Regulation
Enclosure:
As stated 169 121 790611003[
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ENCLOSURE 1 ADDITIONAL RECOMMENDATIONS RELATING TO TMI-2 ACCIDENT IN MAY 16, 1979 ACRS LETTERS A.
Interim Report No. 3 dated May 16, 1979 Examine operator qualifications, trais.ing and Recommendation 1 licensing, and requalification training and testing.
Recommendation 2 - Establish formal procedures for the use of LER in fo rmation:
(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, 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) more 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:
(_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 Recommendation 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 167 122
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 Reconmendation 8 Review and revise within three months:
(a) licensees' bases for obtaining offsite advice and as-istance in emergencies from within and outsice 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 anc recovery of major nuclear power plant syr tems Recommendation 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 te deal with problems in reactor and fuel cycle chemistry in the following areas:
(a) behavio of PWR & BWR coolants and other materials under radiation conditions (b) generation, handling & disposal of radiolytic (or otFer) H at nuclear facilities (c) perfornance $f chemical additives in containrent sprays (d) proces sing and disposal techniques for high and low level radioactive wastes 169 l23
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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 Sincie 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 explcratory (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 May 16, 1979 Amplified many of the recommendaticns 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 recommendations.
(Address amplifications and suggested priority assignments as appropriate.)
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% M. M./ pi wassincTon, o. c. 2:sss Pay 16,1979 Honorable Joseph M. Hendrie Chairran U. S. Nuclear Regulatory Comenission Washington, EC 20553
Subject:
INTERIM REPORT NO. 2 ON 'nREE MILE ISU6'D NUCLOR STATICN UNIT 2
Dear Dr. Hendrie:
During its 229th meeting May 10-12, 1979, the Advisory comenittee on Re-ac*or Safeguards continued it.'
review of the circumstances relatirg to the recent accident at Three Mile Island Nuclear Station Unit 2 (TMI-2).
Tne recomcnendations presera_ed orally to the Commissioners on April 17, 1979 were reviewed by the full Committee and are repeated in romewhat amplified form herein. Inplification of these items is responsive to the reqJest of Acting NRC Chairran Victor Gilinsky dated April IS,1979.
Natural Circulation - Procedures It is evident from the experience at TMI-2 that there was failure to es-tablish natural circulation of water in the prirary system and failure to recognize in a timely ranner that ratural circulation had not been achieved.
The need for natural circulation under certain circu stances is correa:n to cl1 Paps.
Tne Com.nittee recommends that procedures be developed by all operators of PnRs for initiating ratural circulation in a safe manner and for pro-vidirs the oparator with assurance that circulation has in fact been es-tablished. Tnese pr-edures should take into account the behavior of the systems under a
.ty of abnormal conditions.
As a first step, the NRC Staff should initiate ir. mediately a survey of op2 rating procedures for achievirrg ratural circulation, including the case when offsite p:wer is lost. At the same time, the operators of all PdR plants should be regaested to develop detailed aralyses of the be-hav.for of their plants follcwing anticipated transients ard small breaks in the prirary system, with appropriate considerat:en of Ectential ab-normal conditions, opnator errors and failures of eToic.ent, pcwer sources, or instrumentation.
Tnera analyses ara necessary for the 169 125 y
Honorable Joseph M. Hendrie yay 16,1979 development of suitable operating procedures.
The revie.' and evaluation of these analyses by the NRC Staff 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 requires the maintenance of a suitable over-pressure on the reactor coolant system in order to prevent the genera-tien of steam which can impede circulation.
For many transients, main-tenance of this overpressure is best accomplished by use cf the pres-suriner heaters.
Although the pressurizer heaters at TMI-2 continued to receive power f rom offsite sources curing the entire accident, the availability of offsite power cannot be assured for all transients or accidents during which, or following which, natural circulation must be established.
The Cor:mittee recor= ends that the NRC Staff initiate irmdiately a survey of all PGs licensed for operation to determine whether the pressuricer heaters are now or can be supplied with pcwer from qualified onsite sources with suitable redundancy.
Natural Circulation - Saturation Conditiens The plant operators should be informed adequately at all times 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-atore 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 conjoction with conventional steam tables.
The Cccmittee recomends that information for 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 proyiding this information, there is no need for the NRC Staff to as-sign a bigh priority to the development of prescriptive requirements for such displays.
Mcwever, a reasonably early request that licensees and vendors consider and ccmment en the need for s;ch a display would be arrrepriate.
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Honorable Joseph M. Hendrie May 16,1979 Core Exit Thermecouples 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 r.atural circulation or the status of the core. For the latter purpose, it is recen ended 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.kould be appropriate 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 consideration of this recommendation would not at this time seem to require a high priority.
Instrumentation to Follow the Course of an Accident The ability to follow and predict the course 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 long been a concern of the ACRS, is the subject of Regulatory Guide 1.97 (which has not yet been implemented on an cperating plant), and is the subject of an NRC Staff Task Action Plan for the resolucion of generic issues.
The Committee believes that the pasitions of Fegulatory 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 TdI-2 should be the bases for these reviews.
For ex-ample, impcoved sampling pracedures under accident conditions should be considered.
Althcagh 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 provide suf ficient basis for planned and appropriately phased actions. te Committee believes that the installation of improved instrumentation on operating reactors -f all types should be underway within one year.
169 127 3
Ecnorable Joseph M. Hendrie May 16,1979 Reactor Safety Research The ACES recomends that safety research on the behavior of light-water reactors during anomalous transient _s be initiated as socn as pessible and be assigned a high priority.
'me ACRS would ex:ect to see plans and propesals within about three months, preliminary results within an additional six months, and core comprehensive results within a year.
Of carticular interest would be the development of the capability to simulate a wide range of p:stulated transient or accident c:nditiens, inclucing various abnormal or low probability mechanical failures, elec-trical failures, or human errors, in order to gain increased insight into measures that can be,taken to i.mprove safety.
The new prcgram of research to improve reactor safety Fas been initiated only recently, and then only on a relatively small scale.
Tne Cc =ittee reiterates its previous recomendations that this program be p;rsuad and its expansion scoght by the Comission with a greater sense of urgency.
Status Monitorin:
Although the cicsed auxiliary feedwater system valves may not have con-tributed directly or significantly to the core dama:e or environmental releases at ?'.!-2, the potentially much more severe consecuences of un-availability of engineered safety features in plants of any type is of concern and deserving of attenticn.
Status monitorirs not depandent chiefly on aiministrative control, and thus possibly less subject to hu-man error, might help assure the availability of essential features.
A reg;est should be made within the next few cenths that lic2nsees con-sider additicnal status monitorire of varicus engineered safety features and their supporting services.
'Be GC Staff should begin studies on the advantages and disadvantages of such nonitoring co about the same time scale.
Responses from licensees should be expected in about one mr, at stich time the NRC Staff should be in a position to review an' alu-ate them.
'~ne. Ccanittee recognizes that some of the recca:#nded actions in this report have already been taken by the NRC Staff.
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WASHINoToN, D. C. 20555 May 16, 1979 Honorable Jeseph M. Hendrie Chairman U. S. Nuclear Regulatory Commission Washington, EC 20555
Subject:
INTERI.M REPORT NO. 3 ON 'IERIE MILE ISur NJCLOR STATION LSIT 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), including implications drawn f rom the occurrence of this accident. The Cccrnittee has several addi-tional reco m endations to make at this time.
Reactor Pressure Vessel Level Indication The Com-ittee believes that it would be prudent to consider exteditiously the provision of instrumntation that will provide an unarbiguous indica-tien of the level cf fluid in the reactor vessel.
We suggest that licens-ees of all pressurized water reactors be recuested to submit design pro-This would assure posals and schedules for accomplishing this ection.
the timely availability of reviewed designs if the Staf f o >goirg studies Tc.e Committee should indicate that early implementation is recuired.
believes that as a minimum, the level indication should rar.ge free the bottem of the hot leg piping to the reactor vessel flange area.
Cperator Traininc and Qualification The NRC Staff should examine operator qualifications, training, and li-censire to derennine @at changes are needed. Ccnsideration should be given to educational background, to training methods, and to centent of Attentien should also be given to testing methods, the training program.
with specific concern for the ability of the testinc methods to predict operator carability.
Examination of licensirq procMures should deter-mine whether they are responsive to new infocution that is develowd a'ccut plant or ope rator performance.
Ef fort should also be made to mjaAahO - %
-- - m deterrine -t. ether resuis of examin me ator abilitv.
. ecualification tral.
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DUPLICATE DOCUMENT Entire document previously entered into system under:
7 OCMocDO 129 ANo No. of pages:
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