ML20197J789

Questions Technical Adequacy of FEMA Std for Judging Siren Sys for Nighttime Conditions.In summer,10% of People & in winter,15-30% of People Will Not Be Alerted.Number Considerably Less than FEMA Std.Served on 860516

ML20197J789
Person / Time
Site:	Harris
Issue date:	05/16/1986
From:	Bright G, Carpenter J, Kelley J Atomic Safety and Licensing Board Panel
To:	Asselstine J, Palladino N, Roberts T NRC COMMISSION (OCM)
References
CON-#286-178 OL, NUDOCS 8605200170
Download: ML20197J789 (4)

Text

'

@ gews a/61986

• . UNITED STATES g \[* i e

f

<>( o NUCLEAR REGULATORY COMMISSION m" N f ATOMIC SAFETY AND LICENSING BOARD PANE W ASHIN GTON, D.C. 20555 7 ,

"D May 16, 1986 -

Af/}yy61986 % 3

] s$%yy $ s

1. m. -

Chairman Nunzio J. Palladino M Commissioner Thomas M. Roberts 'G#

Connissioner James K. Asselstine Commissioner Frederick M. Bernthal Commissioner Lando W. Zech, Jr. DET N'""'ER

Dear Mr. Chairman and Connissioners:

fROD. L UTIL FAC.. () (

On November 19, 1985, we wrote to you to express our concerns, arising out of the Shearon Harris operating license proceeding, that existing siren systems at other nuclear plants might be deficient for nighttime alerting. On April 28, 1986, we issued our decision on the remaining contentions in the Shearon Harris case, including nighttime alerting, and authorized issuance of fuel loading and operating licenses for that facility. We found that the overall Shearon Harris alerting

• system, where sirens are to be supplemented by a tone alert radio in,the bedroom of each residence in the first 5 miles of the 10-mile EPZ, meets applicable requirements under summer nighttime conditions.

Nevertheless, our findings in the Shearon Harris case underline our generic concerns about nighttime alerting at reactors which rely entirely on sirens and so-called "infonnal alerting" (initiated by the sirens) in the first-15 minutes following a declared emergency.

We continue to be concerned about the technical adequacy of the FEMA standard for judging nuclear power plant siren systems for nighttime conditions. As discussed in more detail in our decision, the FEMA standard for a nuclear plant siren system in a sparsely-settled area like Shearon Harris is that it produce a minimum sound level of 60 dB (decibels) outdoors throughout the EPZ. This standard is applied to summer daytime conditions, the time least favorable for sound propa-gation. However, as the record in the Shearon Harris case shows, the time least favorable for actually alerting people is midnight to 6 a.m.

when virtually everybody is indoors and asleep. Although nighttime conditions are more conducive to sound propagation, that advantage is much more than offset by closed bedroom windows and the state of sleep.

Our second concern is with the Staff's position, as expressed in the Executive Director for Operations' memorandum to you of February 24, 1986, which states in pertinent part as follows:

.The conclusion reached in: FEMA's study, in response to the

ShearonHarris]hearingcontention,thatthissirensystem

. supplemented by informal alerting] can be expected to arouse and alert approximately 90% of the EPZ residents during a 8605200170 860516 PDR ADOCK 05000400 G PDR Osoz.

nighttime emergency serves to confirm FEMA's judgment that siren systems designed and evaluated in accordance with NUREG-0654/ FEMA-REP-1, Rev. I and FEMA-43 meet the NRC requirements for both daytime and nighttime alerting.

Unlike the Stcff, we would not accept a 90% alerting level as meeting the Commission's requirement of " essentially 100%" alerting in the first 5 miles of an EPZ. We held that " essentially 100%" means a notification system capable of alerting greater than 95% of the EPZ residents in the first 5 miles. We therefore held that the 91% level expected for the Shearon Harris sirens and informal alerting was insufficient. However, with the addition of tone alert radios at Shearon Harris, an alerting level of 98% can be expected, a clearly satisfactory level in our view.

Our third generic concern arises from a realistic scenario which the Shearon Harris case and the FEMA / Staff position do not address --

winter nighttime alerting. The Harris contention was focused on summer nighttime conditions apparently because the Intervenor believed that noise from air conditioners made that the " worst case." The evidence showed that air conditioner noise, typ.ically in the lower frequency range, had only slight effects on alerting. The key factor is whether i the bedroom windows e.re open or closed because closing the window attenuates sound intensity by about 28 dB. In the Shearon Harris case, the study on which FEMA relied was based on the assumption that about 50% of the windows are open on a summer night in Eastern North Carolina.

In the winter, however, we would estimate that perhaps 75-90% of bedroom windows in that area would be closed. In an EPZ in a colder climate --

say, in Maine or Minnesota -- we would expect that most people would l

also have storm windows and that virtually all bedroom windows would be closed at night. That expectation is borne out by a 1982 NRC Staff analysis titled " Evaluation of the Prompt Alerting Systems at Four Nuclear Power Stations," NUREG/CR-2655, PNL-4226, which projected the following siren alerting rates under nighttime conditions:

Plant Conditions Rural Area Trojan WinterNight(Rain) 60%

TMI Winter Night (Snow) 42%

Zion Winter Night (Windy) 51%

Indian Point Winter Night (Snow) 53%

Similarly low alerting percentages could be expected as a result of closed windows in hot sunmer climates.

To be sure, the large gaps between these alerting percentages and the Commission's requirement of " essentially 100%" will be partly filled by informal alerting. If one assumes that 50% of the alerted households would engage in informal alerting, overall alerting for the above four

o 4

EPZ's would range from 54% to 72%. Using TMI to illustrate that computation, with 42% direct alerting the 50% assumption would result in 21% of the alerted households attempting to alert others. This 21%

might successfully alert a non-alerted household 58% of the time (42% of the time an already alerted household would be contacted). Twenty-one percent multiplied by 58% produces an alerting increment of 12%, so that the initial 42% would be increased to a 54% alerting level.

Furthermore, as the Shearon Harris record shows, the estimates in NUREG/CR-2655 were based on questionable data and are probably low by 10-20 percentage points. Nevertheless, even after taking account of informal alerting and factoring in the most relevant data on the arousal capabilities of sirens, the nighttime alerting percentages for the four plants would probably range from about 70% to 85%, falling well below even the Staff's lenient 90% standard. Such levels of alerting cannot reasonably be viewed as satisfying the " essentially 100%" regulatory requirement.

We refrained from raising a wintertime alerting issue in the Shearon Harris case on our own motion only because the licensee is to install tone alert radios, supplemental to the sirens, in the bedrooms of residences in the first 5 miles of the EPZ. {n our judgment, there -

is a serious question whether other existing siren systems, in the" absence of an equivalent supplemental system for nighttime alerting, can meet regulatory requirements, particularly under winter nighttime conditions. There are several supplemental alerting technologies (such as tone alert radios, automatic telephone dialers, activation of alerting devices with signals carried by regular household power lines, and mobile sound sources) that can be anticipated, in conjunction with siren systems already in place, to alert more than 95% of sleeping people in an EPZ in any season of the year. It appears that such systems can be cost effective. For example, in the Shearon Harris case, the Applicants testified that the approximate cost of purchasing and distributing tone alert radios to about 600 houses in the first 5 miles of the EPZ would be $80,000.

In summary and conclusion, the practical effect of the FEMA and NRC Staff positions on nighttime alerting in 15 minutes based on sirens and informal alerting are that (1) in the summer, about 10% of the people will not be alerted (more in hot climates), and (2) in the winter in cold climates, 15-30% of the people will not be alerted. If the Comission agrees that such alerting levels are acceptable and correspond to an absence of undue risk in the first 5 miles of an EPZ, then the present regulatory stariard of " essentially 100%" alerting should be changed. If not, we recommend that timely action be taken to ensure that siren notification systems at existing nuclear plants are

b O

~

' reviewed against appropriate technical and legal standards and

~

supplemented, if necessary.

Respectfully submitted, b 7 JpsL.Kelley [

an1 Y.fe'urdN/v b 0

JamecH.Carppter W O')

Gleh 0. Bright #

cc: M. Malsch, Acting General Counsel S. Chilk, Secretary Shearon Harris Service List ,

I

_ . . . - - --