ML20052D512
| ML20052D512 | |
| Person / Time | |
|---|---|
| Issue date: | 12/10/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| RTR-REGGD-01.023, RTR-REGGD-1.023 ACRS-1921, NUDOCS 8205060527 | |
| Download: ML20052D512 (17) | |
Text
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8 DATE ISSUED:
12/10/81 MINUTES OF THE ACRS SUBC0f1ITTEE MEETING 04 g
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//,l ha INTRODUCTION The ACRS Subcommittee on Regulatory Activities held a.neeting on November 11, 1981, at 1717 H Street, N.W.,- Was,hington, D.C.
The entire meeting was open to public attendance.
Mr. Sam Duraiswamy was the Designated Federal Employee for the meeting.
A list of documents submitted to the Subcommittee is included in Attachment A.
ATTENDEES ACRS:
C. P. Siess (Subcommittee Chairman), M. W. Carbon, J. J. Ray, D. A. Ward, W. Kerr, D. W. Moeller.
S. Duraiswamy (Designated Federal Employee)
Principal NRC Speakers:
L. Beratan, L. Brown, R. Kornasiewicz, B._ Zalcman, I. Spickler, S. Ramos.
EXECUTIVE SESSION Dr. Siess, the Subcommittee Chairman, convened the meeting at 8:30 a.m. and indicated that the purpose of the meeting was to continue the review of Revision 1 to Regulatory Gudie 1.23, " Meteorological Measurement Programs for Nuclear Power Plants", dated October 27, 1981 which was revised subsequent to the October 14, 1981 Regulatory Activities Subcommittee meeting to incorporate the suggestions provided by the Subcommittee at that meeting. He said that the Subcommittee had received neither written comments nor requests for time to make oral statements from members of the public. He mentioned that the Subcommittee had received some written comments from fir. Bender.
DESIGUATED ORIGIliAL 8205060527 811210
Regulatory Activities November 11, 1981 REGULATORY GUIDE 1.23, REVISION 1, " METEOROLOGICAL MEASUREMENT PROGRAMS FOR NUCLEAR POWER PLANTS", DATED OCTOBER 27, 1981 Dr. Siess provided a preamble, indicating that this Guide includes some additional requirements for equipment and program for meteorological measure-ments.
These additional requirements are mainly to meet the need for emergency preparedness and emergency management; none of the additional requirements are needed for the uses made of meteorological data to satisfy the requirements of 10 CFR Part 100 for Siting, of 10 CFR Part 50, Appendix I for "As low As Reason-ably Achievable ( ALARA)" criterion, or for environmental impact assessments. He said that a previous version of this Guide, dated September 1981, was reviewed by the Regulatory Activities Subcommittee at the October 14, 1981 meeting. At that meeting the Subcommittee raised several issues and did not complete its action on this Guide pending resolution and/or additional clarification of those issues.
It suggested that the NRC Staff provide additional infonnation and/or clarification in the following areas and resubmit this Guide to the Subcommittee for consideration at a future meeting:
' Clear identification of the additional requirements included in this Guide along with the bases for them.
' Comparison of and difference between the requirements of Regulatory Guide 1.23, Revision 1 and Safety Guide 23.
' Contribution of the additional requirements of this Guide to public health and safety.
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' Justification of the cost and manpower associated with the implementation of the additional requirements of this Guide with respect to the benefits expected of these requirements.
' Priority for implementing the requirements of this Guide as compared to the other requirements that are being placed on applicants.
He said that this Guide has been revised somewhat subsequent to the October 14, 1981 Regulatory Activities Subcommittee meeting. However, the additional infor-mation provided by the NRC Staff is deficient. He suggested that the NRC Staff
Regulatory Activities November 11, 1981 provide more infomation on the additional requirements of this Guide and the bases for them during the subject meeting.
With regard to the comments provided by Mr. Bender in his letter dated November 6, 1981, (Attachment B).
Dr. Siess said that he believes that most of Mr. Bender's comments are related to the use of meteorology in 10 CFR Part 100 siting criteria. There are new philosophies being developed on siting from the standpoint of safety, not from the standpoint of environ-mental reports, and therefore, he believes that there may be changes in the siting area. Also, it is not clear whether meteorology is still going to play a significant role in the siting area.
Regarding Mr. Bender's comments, Dr. Kerr said that it seems that Mr. Bender's concerns are not completely with Regulatory Guide 1.23, Revision 1, but mainly with the regulatory practices in the meteorological area.
Dr. Carbon said that he believes that Mr. Bender's concern is on the need for such a sophisticated meteorological measurement program called for in this Guide; Mr. Bender does not believe that improving the accuracy of the metcorological data without reducing the uncertainties associated with the source term is going to help.
Dr. Carbon commented that localized meteorolgoical data may be useful to analyze the situation just immediately after an emergency.
However, since it may take several hours for a radioactive plume resulting from an incident to reach a popu-lated area, it is not clear to him how localized instantaneous meteorological data of an improved nature are all that important to analyze the impact on the people, living at a certain distance, after a certain period of time.
He be-lieves that broader meteorological data base from the National Weather Service l
Station may be more helpful and important to analyze the problem several hours after an cmergency.
Mr. Zalcman responded that, based on operating experience, he believes that the peak problems due to most emergency situations occur normally within a distance i
of about two to five miles of the plant. The localized meteorological data are necessary for the licensee to assess the problem and take immediate actions, l
and also to recommend preventive and/or protective actions to local and state
- agencies, c
. Regulatory Activities November 11, 1981 Dr. Carbon asked, since local and state agencies may depend largely on the broader data base from the National Weather Service Station for making decisions during an emergency, how much contribution localized meteorological data are going to provide for such decision-makings.
Mr. Zalcman responded that the National Weather Service data may play an important role in assessing the problem beyond a certain distance from the pl ant. The localized real-time meteorological data are nece'ssary for the licensees to assess the situation in the close vicinity of the plant and to take appropriate actions.
Further, there are many locations where the closest National Weather Service Station may not be able to provide real-time localized meteorological data in the close vicinity of the plant.
Al so, since the National Weather Service Stations are not geared to nuclear power plant operations, the information provided by them may not be adequate to assess the problem during an emergency in the close vicinity of the plant.
Dr. Carbon asked whether the real-time localized meteorological data are going to be of real benefit in predicting the situation five or ten hours after the emergency has occurred.
Mr. Zalcman responded that the real-time meteorological infomation can be used as the best indication of what will happen over the next hour.
Dr. Siess asked how much improvement in accuracy of assessing the problem is going to be achieved by the changes that are required in Regulatory Guide 1.23, Revision 1.
Mr. Zalcman responded that the information expected from the changes to Regulatory Guide 1.23, Revision 1, will help reduce uncertainties by a considerable amount in predicting the radioactive material release pathway.
Dr. Siess asked whether they are concerned about the large uncertainties j
associated with the source term.
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Regulatory Activities November 11, 1981 c.
Mr. Zalcman responded that they are trying to reduce the uncertainties and improve the source term.
But. while they are trying to get a better handle on the source term, he believes that they should also have better meteorological informaiton for use in realistic dose assessments.
Mr. Ward commented that he does not quite agree that the t;acertainty in the source term is a reason to ignore trying to get better meteorological data.
m Dr. Moeller commented that, in case of any kind of an accident, regardless of the accuracy of the source term, the major release pathway for radioactive material is going to be through the atmosphere. He belieu s that the informa-tion obtained through this Guide 'may help to predict the radioactive material release pathways through the atmosphere.
Dr. Siess suggested that it would be worthwhile to go through the Regulatory Positions of this Guide to see what additional requirements are being placed in this revision, and on what basis, as compared to Safety Guide 23. Accordingly, the NRC Staff provided the following information:
Regulatory Position C.1 - Some of the changes made in this position are to:
' Reference Regulatory Guides 1.97,1.111, and 1.145 for additit nal guidance.
' Provide more flexibility for determining atmosphenc stability.
- Provide more definitive guidance for sites with special features l
(coas.tal and valley sites).
It specifies that supp'emental towers or masts, special meteorological instrumentation, data analysis techniqces or field studies may be needed for those coastal and valley sites that do not have such features now.
I Dr. Siess asked about the schedule for implementing the additional features (supplemental towers or masts, special meteorological instrumentation, etc.)
l in the operating plants.
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Regulatory Activities November 11, 1981
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'4r. Zalcman responded that all operating plants should have these systems in place by the end of 1982.
He said that the applicants would be able to in-stall these sytems within a period of six months.
Dr. Siess commented that if the applicants did not have to spend their time and effort complying with so many other NRC requirements, they might be able to complete installation of these systems in six months or even less; however, this is not the case and they have to worry about several other NRC requirements that they might have to comply with within the same six-month period.
Dr. Kerr commented that the last ' paragraph in Regulatory Position C.1, which states "The preparation of estimates of atmospheric transport and diffusion....
so as to aid, in the description of regional airflow patterns", does not seem to provide any specific guidance to the applicants.
He suggested that certain changes would be helpful to enforce and to evaluate compliance. The NRC Staff agreed to make appropriate changes.
Regulatory Position C.2 - In addition to providing more definitive guidance than Safety Guide 23, this Position specifies that a meteorological measure-ment program should include a backup system to provide meteorological data in the event the primary system cannot provide the basic parameters. The NRC Staff indicated that such a system may cost about $5,000.
Mr. Ward commented that the purpose of the sentence in the third paragraph of Regulatory Position C.2 which states, "The 60-meter level generally coincides with other release heights for LWRs," is not clear. After discussion the Sub-committee suggested deletion of this sentence. The NRC Staff agreed.
Regulatory Position C.3 - It does not include any additional requirements.
Some of the changes made to this Position are to incorporate, as appropriate, the provisions of Draft ANS 2.5 " Standard for Obtaining Meteorological l
Information At Nuclear Power Sites". There are other changes made to this j
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Position to provide more definitive guidance and addition clarification.
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Regulatory Activities November 11, 1981 Regulatory Position C.4 - It does not include any additional requirements.
Changes were made to provide detailed guidance and additional clarification.
Regulatory Position C.5 - Changes were made to this Position to provide additional guidance as to what the backup system should be capable of doing.
It provides also more guidance concerning the use of wind parameters for atmospheric stability estimation.
Since Safety Guide 23 did not include any explicit information on quality assurance, this Position includes some additional information on quality assurance for meteorological measurement programs.
It includes also a new requirement for meterologicai data access which specifies that provisions should be made for meteorological data access via data transmission from all utility-maintained meteorological systems necessary to characterize l
the plume exposure EPZ; this additional provision is to deal with emergency preparedness.
Dr. Siess commented that this Position seems to include an additional requirement by requiring a computer for meteorological data display.
He commented further that the information provided in this Position on the quality assurance program is inadequate and does not provide any guidance to the Applicants, and he believes that it will be difficult to evaluate compliance on the basis of the information included here.
The NRC Staff said that the footnote under paragraph 4 of this Position provides some explicit guidance on the quality assurance program. Dr. Siess commented that it does not seem to be the proper place to provide guidance on the quality l
assurance program.
He suggested that that information be included in the quality
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assurance section of this Position.
The NRC Staff agreed.
Dr. Siess commented that he is surprised to see so little information on where the meteorological data should be transmitted. He wondered whether it is going to be transmitted to the Nuclear Data Link.
Mr. Ramos responded that it has nothing to do with transmitting information to the i
Nuclear Data Link. The NRC Staff needs to get the meteorolooical data, no matter r
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Regulatory Activities November 11, 1981 what, to assist them in making protective or preventive action recommendations during an emergency.
With regard to the Implementation Section of this Guide, Dr. Siess commented that the information included in this Section is somewhat ambiguous.
He said that the NRC Staff should provide some better means of communication in the Implementation Section of Regulatory Guides.
The Subcommittee suggestd that the information that was moved from the Discussion Section and included in Appendix A, as suggested by Mr. Bender during the Octobe 14, 1981 meetina, be moved back to the Discussion Section.
The NRC Staff agreed.
Af ter further discussion, the Subcommittee indicated that it will submit this i
Guide to the full Committee during the November 12-14, 1981 ACRS meeting recommending concurrence in the Regulatory Positions of this Guide.
It will recommend also to the fc11 Committee that a letter be sent to the Executive Director for Operations recommending that the implementation of this Guide for those plants requiring extensive and expensive upgrading be considered by the recently-established Committee to Review Generic Requirements to deter-mine whether the cost or other burden on the licensees is jusified.
FUTURE MEETING The next Regulatory Activities Subcommittee meeting is scheduled to be held on December 8,1981 to discuss the following:
1.
Regulatory Gudie (Task No. SC 708-4), " Qualification and Acceptance l
Tests for Snubbers Used in Systems Important to Safety" (post comment).
j 2.
Proposed Regulatory Guide (Task No. IC 126-5), " Instrument Sensing l
Lines" (pre comment).
l 3.
Proposed Regulatory Gudie (Task No. IC 127-9), " Criteria for Programmable Digital Computer System in Safety Systems of Nuclear Power Generating l
Station" (pre comment).
l Dr. Siess thanked all participants and adjourned the meeting at 11:00 a.m.
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i Regulatory Activities November 11, 1981 NOTE:
Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room,1717 H Street, N.W.,
Washington, D.C., or can be purchased from Alderson Reporting Company, Inc., 400 Virginia Avenue, S.W., Washington, D.C. 20024, (202) 554-2345.
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- Regulatory Activities Meetina November 11, 1981 LIST OF DOCU'4ENTS SUB!ilTTED TO THE SUBC0ttilTTEE 1.
Regulatory Guide 1.23, Revision 1, "tieteorological Measurement Programs For Nuclear Power Plants," dated October 27, 1991.
2.
NUREG-0654/FE'iA-REP 1, Revisi6n 1, " Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants".
3.
NUREG-0696, " Functional Criteria For Emergency Resoonse Facilities".
4 Draf t A15-2.5, " Standard For Obtaining fieteoroloaical Information at Nuclear Power Plants".
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ATTACHiENT A i
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W ASHINGTON. D. C. 20555 us 9
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November 6, 1981 Dr. Chester P. Siess Professor Emeritus of Civil Engineering 3110 Civil Engineering Svilding University o Illinois Urbana, IL 61801
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Dear Chet:
_Comrents on Re; latory Guide 1.23 As yo. know I won't be able to attend the December Regulatory Guide meeting wher Regulatory Guide 1.23 will be discussed.
If it is to be released as a basis for regulatory requirements concerning emer respor.se, we ought to first discuss it with the Commissioners. gency I am consinced that the NRC treatnent of site meteorology has a badly distorted and response applications. emphasis for all purposes, but it is at its worst for emerg Even though the monetary cost associated with the recuirements is relatively small compared to total power plant costs Of more conceer., however,it is extremely high when related to the actual is the waste of time and valuable manpower needing attenticr. resources by diverting them from more important safety matters really Guide 1.23, but there wasn't time to review my discussio most of it came from mental recollection.
Still, I don't think there are any serious errors in it.
We should recommend to the Commissioners that Regulatory Guide 1.23 be abandoned because its purpose is no longer in keeping with current regulatory safety approaches.
When the guide was introduced, we were using the traditional arbitrary accident source term derived from small fuel melting experiments to establish containment leak tightness.
The nuclide releases were based on a uniform mixture of iodine, noble gases and particulates within the contained atmos-phere.
We know then and now that this was a poor assumption but it was convenient for safety analysis purposes and it is very conservative.
meteorology was mainly used to show the dispersal of radionuclides from the The containment at the prescribed leak rate.
It was completely artificial. The use of such complicated meteorological analysis to show site boundary limits was not much better than using astrological principles to predict core melt.
It was always a lot of mystical hocos pocus.
I ATTACR1ENT B
l Dr. Chester P. Siess November 6, 1981 Since TMI-2 we have known that the approach was nonsense.
We need to consider realistic source terms, but even if we keep the arbitrary source term basis we shouldn't try to use sophisticated meteorology based on very localized measurements to determine site boundary radiation exposure.
Nobody writh even a microgram of common sense would think we could use such data to show radiation exposure of the bulk population following a major accident.
I suspect that much of what-is proposed in Regulatory Guide 1.23 is the product of ACRS inquiries, improperly interpreted, and of licensee pencil sharpening to obtain approval of the less attractive sites, where stagnant air conditions and inversions caused concern for the dilution rates of nuclides dispersed to the environment. We now under-stand that we have not defined what is to be diluted.
All we know is that leakage rates will be higher than assumed for containments but internal containment decontamination will be a great deal higher than-was creditec.
These are offsetting effects that have never been quantitatively related.
1, personally, believe that the decontamination effects are much more of a factor than leak tightness, so the situation will be better than expected, barring, of course, pressurized rupture of containment by some very low probability circumstance.
Such gross l
ruptures were never treated in the dose analysis anyhow.
I don't w6nt to discredit the technological approach used in the Regulatory Guide.
If one is going to use a complicated plume analysis to determine mass transport of nuclides and if the leakage is also small, making its behavior dependent on meteorological conditions, then a knowledge of air layer movement and diffusion will be needed.
- However, if the leakage is small enough for such phenomena to be controlling, then the internal decontamination effects will reduce the nuclide outleakage to levels where their radiation effects can be ignored.
What bothers me most about this analysis is that if public safety were really dependent on such sophisticated understanding of meteorology, we would have great difficulty defending the regulatory posture. We are not depending on such analysis but rather using it as procedural rote intended as a reminder of important phenomenological considerations that affect airborne nuclide transport.
We could handle it much simpler if we recognized the decontamination effects of low leakage events, permitting us to ignore the meteorology.
We should remember that when nuclear power was initially being developed it was common practice to vent gaseous nuclides to the abnosphere.
ALARA had not been invented for effluent control. We used the meteorology to assure favorable conditions for venting.
For that application covered by 10 CFR 20 requirements the meteorological interest made more.ense.
Our current ALARA limits make this venting issue a moot.
f Dr. Chester P. Siess November 6,1981 I can't help but note the similarity between this situation and the air-controller strike circumstances.
In both cases the " overkill" regulatory practice wasn't recognized until the real need was tested.
It is obvious in both instances that safety practice was carried far beyond real need by the momentum of the system. Since wi are pushing risk evaluation principles in regulatory practice, this type of calcula-tional mysticism should lead the list of practices to be discarded.
Sin erelj, M. Sender ME/cw Attachment cc:
- 5. Duraiswa j R.
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MBender Page 1 COMMENTS ON REGULATORY GUIDE 1.23
Background
Regulatory Guide 1.23 has been used for a number of years as the basis for evaluating site acceptability for nuclear power plants.
Its roots lie in the basic accident assumptions used in site analysis.
In the early development of nuclear power plant safety principles it was presumed that certain forms of radior.uclides would be released and the consequences of such releases would be rinipized if sites were selected with favorable meteorology in terms of infrequent air inversions, quiescent air conditions or other factors that would reduce the dilution effects on the nuclides that might be relehsed to the surrounding environment.
This was a logical position in that it avoided selection of less desirable plant sites when more suitable ones were available.
When 10 CFR 100 became the basis for site acceptability, the regulatory evaluation process, through its use of prescribed analytical methods using arbitrary accident assumptions, introduced an arbitrary but rigorous method i
of analyzing site boundary accident effects.
The calculational methods became highly refined because some sites could only be shown to meet very conservative 10 CFR 100 limits by refining the interpretation of meteoro-logical conditions.
The regulatory staff, in order to apply sophisticated meteorological analysis required substantiating data. This in turn led to the requirement for meteorological towers instrumented to obtain data over an extensive time span.
Such data were intended to permit integration of radionuclide release effects over a long period of time. The data were never applied to actual accident release conditions.
The data requirement became ingrained in the Construction Permit processing even though for good nuclear sites it was of little value.
The data was only needed because of the arbitrary calculational procedures used 1
for evaluating conformance with 10 CFR 100 limits. The data was not of use for the TMI-2 accident and it would not be of use for accidents of more serious nature since other factors dominate the public risk considerations.
MBender Page 2 Factors Affecting Airborne Radioactive Dispersions In core ~ damage accidents the physical characteristics of airborne radioactivity are understood only in a gross qualitative manner.
The forms of t!e radionuclides when released from the fuel vary with time because of nuclide radio-decay.
The chemical form of the nuclides depends upon reactions with other materials, the most interesting reaction being the cesium iodide combination which ties two important radioactive constituents together in a cherical compound.
The physical movement of nuclides from the fuel to the exte,rnal containment environment depends upon the pathnay of release (calculated by the Corral, March, Contain Codes or analagous techniques), the containment constituents of which moisture and dust particulates are probably most important, and the temperature and pressure in containment when the release is occurring. These factors represent two to three decades of uncertainty in the nuclide concentrations that could leave the contained atmosphere.
By comparison, the most refined meteorological analysis can improve over the crudest practice by no more than a factor of three.
While we may be able to improve calculational procedures within containment, we can never establish the in-containment accident envirorTent we'.I enough to make the external meteorological conditions a determining factor in evaluating human radiation exposures prior to, during, or subsequent to nuclear accidents.
The meteorological data are of use mainly in timing controlled release of radionuclides over long time spans in the range of months and years.
The noble radioactive gases, mainly Dypton 85, will mix with the contained atmosphere and could be released in accidents. However, the quantity is very small even for a full cora of spent fuel and when dispeksed intheexternalairitwilldiluteregardlessofmeteorologytoac5ncen-tration which will not cause measurable radiation injury at ground level.
Hence, for accident purposes it can be ignored with respect to human exposure during accidents where nuestions of evacuation, escape routes, and local radiation exposure might be involved.
Dispersal of Airborne Activity Released from Containment
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Air plume models are used to analyze the dispersion of particulate radionuclides assumed to be released from containment.
The models always
MBender Page 3 assume a point source and are usually analyzed by assuming several release locations. Ground level (a few meters above the surface) and locations at the high point of containment or the containment stack usually bracket the effects.
The shape and energy content of the plume are the important considera-tions in bulk releases such as a Containment rupture.
Only gross variations in environmental conditions could be treated in the analysis and many of those would be of marginal importance.
The existence or nonexistence of rain, mist. or fog is a major factor.
An air inversion might have an important effect for determining dispersal rates, but analysis probably can only discriminate between a stagnant air velocity, one of a few MPH or a few tens of MPH. This will indicate how fast the plume will move laterally, but higher velocity winds will also mean rapid plume mixing and dispersal.
The combined effect cannot be calculated with meaningful 8'C c u ra cy.
Variations in air temperature and air layering are of importance only for determining exposure if one were measuring integrated effects for long periods of time when the release is continuous and the physical nuclide form is knowr..
The meteorological tower measurements have meaning only in the localized setting where the measurements are made.
They cannot be extrapolated for miles.
Integrated effects will be determined primarily by air and surface activity samples taken subsequent to the release.
The meteorology would hardly enter the evaluation process.
The CRAC code is the analytical technique currently in use for computing airborne accident effects.
It assumes an accident and then analyzes the release of the activity from a point source in containment.
When last reviewed by the ACRS, it still did not account for gross meteorological variations and it did not have the capability to treat air layer diffusional properties. Whether it has or could be refined for this purpose is unclear, but considering other uncertainties the value of such refinement is doubtful.
Nevertheless, if the data required in Regulatory Guide 1.23 is of any use it would have to be shown to be needed in a CRAC-code type of analysis.
t Meteorological Factors of Importance When Nuclear Accidents Occur There are some meteorological considerations of importance when an accident of serious naturo inv@lai
MBender Page 4 1.
Wind directions, if they can influence the time and route of evasuation.
2.
Variation in wind conditions as indicated from weather service sources when a planned release such as venting is intended.
3.
Air stagnancy (inversion) circumstances that might influence dispersal and cause undesirable localized conditions during a planned release.
4.
Flood or tornado conditions that might jeopardize recovery operations. This type of information should come from local weather and emergentj warning services.
Value of Regulatory Guide 1.23 With our present and prospective radionuclide dispersal knowledge, Regulatory Guide 1.23 is not of value for emergency evaluation purposes.
The expressed need based on requirements stemming from NUREG 0654, 0696, and especially NUREG 0737 only indicates that the reference documents are wrong and need correction.
This interest in refined meteorological analysis stems totally from the arbitrary analytical procedures used in determining site suitability to 10 CFR 100 conditions. More than likely, NRC could conserve its own and licensee resources by simplifying the computational procedures and putting more emphasis on such accident assumotions as containment leakage, nuclide dispersal within containment, and lapsed time under which accident conditions prevail.
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