ML20213E733

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Forwards Further Info Re Requirements for Notifying NRC About Releases of Radioactive Matls from Nuclear Power Plants.Slow Progress in Updating Radiological Tech Specs Principal Problem in Area
ML20213E733
Person / Time
Issue date: 01/20/1984
From: Willis C
Office of Nuclear Reactor Regulation
To: Muller D
Office of Nuclear Reactor Regulation
Shared Package
ML20213E720 List:
References
FOIA-86-729 TAC-49588, NUDOCS 8402030553
Download: ML20213E733 (7)


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DISTRIBUTION CENTRAL FILE ETSS Staff METB Suh.i. File 5.2 Jiiehemias METB R/F Gillis ISoickler JAN 201334 H ' Rood

!EPO?.A'!DUM FOR:

Daniel R. Huller, Assistant Director for Radiation Protection D51 FROM:

Charles A. Willis, Leader. Effluent Treatment Systems Section, METB, DSI TiiRU:

William P. Gamill, Chief, METB, DSI

SUBJECT:

tiOTIFICATION AND REPORTING OF RELEASES OF RADIOACTIVE KA.TERIALS As requested, we have reviewed our requirements for notification about, and reporting of, releases of radioactive material from nuclear power plants. The impetus for this review was the apparent uncertainty in copino with the January 1,1984 release from San Onofre Unit 3.' We con-clude that the staff position is clearly defined and that this position has been transmitted to the Regional Offices.

If further clarification is needed, the appropriate action could be an information notice to the licensees.

The enclosure provides further infomation and we are prepared to discuss the ratter at your convenience.' We are also prepared to make a follow-up p: esentation at a future events briefing as requested by Gary Holahan in his January 13, 1984 memorandum.

The principal problem in this area is the sidw progress on updating the radiclogical effluent technical specifications (RETS) for ors. Unless sorethine is done to promote cooperation by the licensees, it seems that a nutber of the ors will not have approved dose calculation methods in the forseeable future.

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Charles A. Willis, Leader Effluent Treatment Systems Section xA Meteorology & Efflue'nt Treatment Branch

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REQUIREt1ENTS FOR. NOTIFYING THE NRC ABOUT RELEASES OF RADIDACTIVE PATERIALS FROM NUCLEAR POWER PLA.NTS Reevirements Recuirements for notifying, and for reportino to, the NRC about radioactive releases from NPP are established by the regulations and by the technical specifications.

The regulations are:

i 20.403.

Notification:

(a)

Immediate:

5000 x MPC averaged over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (b)

One day:

500 x MPC averaged over 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> I 29.4.05.

Reports (30 days):

(a) Any release requiring notification (b)

Concentration as much as 10 x limit (c)

Any violation of 40CFR190 (.05 x MPC averaned over 1 year) 1 50.72.

Notification:

(a)

Imediate (1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />)

(1)

Emergency plan initiation (2) Technical specification violation (b)

Four-hour i

(1) 2 x MPC averaged over 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> (2)

Any event resulting in a news release

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(3) Any event resulting in notification of another covernment

'sgency Despite our concerted efforts, the requirements of the technical specifications (TS) are, not the same for all plants.

Generally the TS do not reouire notifica-V tion based on releases but the TS do include several reportinn ren,uirenents.

Also ' he TS include release limits that, in principle, could triceer notifi-t i

. cation under i 50.72.

The TS release limits nenerally will not crecipitate t

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' notification because the TS include " action" reovirements that keep releases from constituting TS violations.

In some cases (such as San Onofre), where an alarm-level release results in a press release and/or notification of the State Government, 5 50.72 requires notification of the NRC within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

Generally the TS limits on airborne releases that' mav lead to notification of~the NRC are equiyalent to:

('a) noble gas:

1 x MPC instantaneous (b) iodine and particulates:

1 x MPC over 1 week Atmospheric Dilution

'NRC limits are expressed in terms of concentration or dose but these quanti-

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ties are not directly observable.

Licensees measure releases and meteoro-logical parameters.

Doses and concentrations are inferred from these measure-ments. Usually the dilution provided by the exhaust gas flow is neglipible in comparison to atmospheric dilution.

Therefore, the downwind concentration f

'is taken as x = QF/u.

Q is the release rate (Ci/sec), u is wind speed (m/sec) and F is a function l

f l

of distance and atmospheric stability (m-2).

Both F and u are subject to l

large (2 orders of magnitude) fluctuations in short periods of time.

l The instantaneous concentrations are of little practical' importance. The radiation doses that result are determined by the intecral of the concentre-Most of the relevant limits are for a one year period; for v

tions over time.

example, 500 mrems in one year.

Since.the release rates are relatively con -

stant and s4nce changes in,rel. ease rates usually are indenendent of neteorolog-ital conditions, exposure estimates ar.e based on annual average meteoroionical

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. Potential Problem From Notification Recuirements Toda.v the technology is a.vailable to permit evaluation of offsite concentra-tiens using meteorology that is concurrent with releases.

If this were done and the results used as a basis for notification, such notifications would be quite frequent.

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To understand the problem, consider that in 1980 the average BWR released

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noble gases at the rate of about 1.7 mci /sec. This meets the ALARA, criteria (of Appendix I) if the annual average dispersion factor.i.s 1 x 10-5 or less.

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However, at some such plants, about 5% of the time (400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> /yr) the.disper-sion can be expected to be so poor (type F stability with 1 m/,sec wind) that the offsite concentration exceeds 2 times the P.PC.

Thus, if the requirement

.of 50.72 were interpreted as requiring the use of concurrent meteorolony, some plants would be notifying the NRC about releases almost daily even t' hough releases were normal.

The problem is further conplicated by the practical limitations on wind speed measurements.

At most sites the measured value is zero on the order of 1% of the time (90 hours0.00104 days <br />0.025 hours <br />1.488095e-4 weeks <br />3.4245e-5 months <br /> / year).

Whenever the wind speed falls to zero

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the calculated concentration will exceed twice the !1PC unless the radio-l

. activity releas'e rate also is zero. Thus, even a PHR on a large site would be required to notify the NRC about releases frequently, perhaps once or twice per week.

t-Significance of !!otification-Level Concentrations Even 'the highest;bf the notification levels (5000 x liPC averaged over i day) ^

is about-a Int.or of 10 below a level ~at which any health effect (nausea)

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While every release may be assumed to increase the can:er risk, thousands of releases at this level would be required to oroduce a discernible increase.

Thus the notification levels are not levels at which there is a real. concern about public health and safety.

The notification levels were established to call,NRC' attention to poor radia-tior, control practices by licensees.

Liniting Frecuency of Notifications It is important that the NRC not be notified every time the wind speed drops belcw the limit of measurement.

In fact, notification should be limited to relatively important events.

In principle this could b'e done by keeping cen:entrations below the MPC levels at the release points, thereby elimina-ting reliance on atmospheric dilution.

In practice, however, this would be cuite costly if not completely infeasible.

Even for plants with minimal

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releases (such as Yankee Rowe in 1980) it would be necessary either to reduce releases or to increase airflow if MPC levels were to be reached at the release poir.ts.

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The practical solution is to permit the use of annual average atmospheric dispersion in assessing compliance with the notification requirements.

This approach, in various guises, has been standard for many years and was recent-ly reaffirc.ed.* The Technical specifications (usually),are clear 6n this p:f r.t but the regulations ne'ed interpretation.

This is expected to hold

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n::ification frequency to an acceptable level.

The use of annual average atrcsbheric dispersion permits the use of alare set-points that do not fluct'ulte

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" L. J. Cunningham, " Inspection Gu,idance - 50.72," Menorandun to Robert C-recer,

';:v ember 15, 1983.

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I't also avoids over-reliance on complex conputer systems and permits reactor operation at constant power throuch changing weather conditions.

The use of annual average atmospheric dispersion is intended as an option for the licensee.

In some situations the use of "real time" dispersion may be desirable.

For example, the NRC does not object if.a licensee wants to empty a waste gas tank relatively rapidly at a time when the wind wi.ll prry the radioactive gas out 'to sea or when dispersion condit. ions are good.

Dose Calculation Methodolov

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The methods for calculating doses 'are well established by renulatory guides and topical reports.

Further, the NRC has recently published a textbook on radiological assessment that compiles this information in a single document and that provides additional clarification.

Many of the NPP licensees have established their own dose calculation nethods in NRC-approved documents called "offsite dose calculation nanuals." When the current effort to update the radiolog'ical effluent technical specifica-tions (RETS) for ors is complete, all NPP licensees will have approved dose calculation methods.

The most significant remainino problem in this area is the slow prooress on RET 5.

About half the ors do not yet have approved dose calculation nethods.

Current indications are that about a quarter of the ors will not have approved nethods in the forseeable future.

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