ML20246E406

Provides Addl Info Re Questions on Staff Proposed Purging of TMI-2 Containment Bldg Atmosphere

ML20246E406
Person / Time
Site:	Three Mile Island
Issue date:	05/30/1980
From:	Harold Denton Office of Nuclear Reactor Regulation
To:
Shared Package
ML20244A768	List: ML20244A765 ML20246E389 ML20246E395 ML20246E400 ML20246E406
References
FOIA-89-88 SECY-80-132D, NUDOCS 8905110253
Download: ML20246E406 (3)

Text

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- . UNITED STATES ,

NUCLEAR REGULATORY COMMISSION ~

May 30,' 1980' WASHiriGTON, D. C. 2o556

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! INFORMATION REPORT , .

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For: The Commissioners

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Harold R. Denton, Director From:

Office of Nuclear Reactor Regulation , s -

O Thru: - Executive Director for Operations

Subject:

TMI-2 CONTAINMENT BUILDING PURGE

Purpose:

To provide additional information regarding questions on the staff's proposed purging of the TMI-2 Containment Building atmosphere. (See SECY-80-132C)

Discussion: The attached submits supplemental information on the slow purge alternative.

Coordina tion _: The action was concurred in by the Office of the Executive Legal Director. ,

! A Harold R. Denton, Director Office of Nuclear Reactor Regulation

Enclosure:

Supplemental Slow Purge Information (SECY-80-132C) cc:

Commissioners Comission Staff Offices ACRS SECY

. SECY NOTE: The subject of this paper and other related papers is scheduled for discussion at a Comission meeting on Thursday, June 5,1980.

Contact:

B. J. Snyder

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Supplemental Slow Purge Information The slow rate purge alternative recommended by the NRC staff would be carried out within several limiting conditions. Most importantly, purging would be controlled to limit the cumulative maximum individual offsite dose resulting from the purge to less than the annual Appendix I to 10 CFR 50 dose design objective (5 mrem whole body, 15 mrem skin). Oose would be tracked during actual purging by using real time meterological data to calculate hourly dose rate in affected sector / sectors surrounding the plant. (The region around TMI is divided into 16 directional sectors; wind directional changes during purging will result in differing dose rates for individual sectors.)

Cumulative dose, based on these calculated dose rates in each impacted sector, would be updated hourly throughout the purge process. No hypothetical person in any sector would be permitted to receive a dose in excess of the Appendix I dose design objective. For example, if the calculated cumulative dose to a hypothetical person, based on actual Kr-85 release rates and real time meteor-ology, reached the annual Appendix I whole body (5 mrem) or beta skin (15 mrem) dose objective in the North sector, purging would be discontinued whenever existing wind conditions could result in any incremental increase in dose to the North sector.

In addition to Appendix I constraints, the slow purge procedure would be limited by the existing Three Mile Island effluent release technical specifi-cations for Kr-85. Although these specifications have dose limitations In as their bases, they have been implemented as Kr-85 release rate limits.

centrast to the Appendix I limit, dose rates and cumulative dose are not n.. iitored to show conformance with release rate technical specifications.

Release rate (Kr-85) alone determines conformance or non-conformance with the technical specifications.

One Kr-85 release rate technical specification requires that instantaneous rates not exceed 45,000 pCi/sec. This instantaneous limit is derived from the annual average x/Q (6.7 x 10 6 sec/m3 ) for the TMI site and the maximum per-missible concentration (MPC) for Kr-85 in unrestricted areas as listed in 10 CFR 20. This specification provides for short-term operational flexibility (in normal operating plants and the purge). Any extended release at this relatively high rate would quickly become limiting to operation because the cumulative Appendix I dose restriction also limits the conduct of the purge alternative.

A quarterly averaged release rate technical specification limit of 7200 pCi/sec, sec/m3 ), would also be ,

based on a more restrictive x/Q value (4.2 x 10 5 )

applicable to a slow purge. This quarterly averaged release rate limit is I based on not exceeding, in one quarter, four times the annual Appendix I dose design objective. Again this specification provides for relatively short periods of operational flexibility because relatively high release rates (and hence dose rates) can be averaged in a quarter with relatively low release j rates. Cumulative Appendix I dose, however, cannot be exceeded.

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2-Dose and dose rate during a Kr-85 purge are dependent on three variables; the Kr-85 release rate, meteorological dispersion and the Kr-85 dose conversion factor. Only the Kr-85 dose conversion f actor is a fixed value,*[**~," .

While meteorology (x/Q sec/m 3 ) cannot be controlled during a purge, release During periods

' rate (Ci/sec) can be adjusted to limit the resulting dose.

of less favorable meteorology, therefore, release rates can be selectively Licensee procedures for main-reduced to maintain desired dose rate levels.

taining acceptable purge dose rates during varying meterological conditions, by varying release rates, have been reviewed and approved by the NRC staff.

It should be noted that the first paragraph (pp. 4-5) of the original discus-sion of the slow purge alternative in SECY-80-132C is somewhat misleading. In this paragraph the NRC staff was attempting to set out (for comparison to fast p;rging) the probability of having favorable meteorology under which the slow parpe could be conducted. This discussion assumed a fixed release rate (which is not necessarily the case) in an attempt to provide correlation between the probabilities of having favorable meteorology for slow and fast purge alterna-tives during different times of the year. This discussion is misleading, however, because there is no meteorological threshold for slow purging.

Release rates can be adjusted to near 0.0 Ci/sec to effect acceptable dose rates during poor meteorological conditions.

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December 3 0, 1986 h

g EREEDOM 0F INFORMUl0N ACT REQUEST r .3 Custodian of Records Department of Justice f0M -N ~M y

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10th & Constitution Avenue j;6 G, p;#p y, N.W. Washington, D.C. 20530 oo m bO  !

Dear Sir / Madam:

Pursuant to the Freedom of Inf ormation Act, please provide me with the following documents:

1. Any bibliography or list of all documents relating or making ref erence to the March 1979 accident at the Three Mile Island Nuclear f acility;

2. Any bibliography or list of all documents relating or making reference to leaks of radiation from the Three i Mile Island f acility that occured prior to and following the March 1979 accident

3. Any bibliography or list of all documents relating or making reference to the radiation monitoring system at the Three Mile Island f acility prior to, during, and after the March 1979 accident;

4. All safety reports, letters, memoranda or other papers written by Admiral Hyman G. Rickover concerning the Three Mile Island f acility;

5. All draf ts of the report on the Three Mile Island accident commissioned by President Jimmy Carter, including the earliest, unexpurg at ed versions;

6. All working papers and memoranda used in draf ting tne President's Commission report;

7. All draf ts of the President's Commission report;

8. All memoranda ,and working papers used in draf ting ,

the Nuclear Regul atory Commission's report conducted I under the direction of Mitchell Rogovin; D

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LEVW AND F18HBEIN l

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I Custodian of, Records '

Department of Justice December 30, 1986 PAGE TWO

9. All drafts of the report conducted under the direction of Mitchell Rogovin.

10. All documents relating or making ref erence to the March 1979 accident at the Three Mile Island Nuclear facility;

11. All documents relating or making ref erence to leaks of radiation f rom the Three Mile Island f acility that occured prior to and following the March 1979 accident;

12. All documents relating or making ref erence to the radiation monitoring system at the Three Mile Island f acility prior to, during, and af ter the March 1979 accident.

Prior to delivering these documents, please' advise us on the approximate cost of photocopying.

Thank you for your attention to this matter.

Very truly yours, C

David J. Perlman dc

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