ML20031E893

Submits Comments on Wind Analysis Contained in Fsar.Design Wind Speeds for Facility Are under-rated.Certain safety- Related Equipment Not Listed as Fully Protected Against 300 Mile Per Hr DBT

ML20031E893
Person / Time
Site:	Trojan File:Portland General Electric icon.png
Issue date:	10/08/1981
From:	Buske N SEARCH TECHNICAL SERVICES
To:	OREGON, STATE OF
References
TAC-12369, NUDOCS 8110160524
Download: ML20031E893 (2)

Text

,,,

6HW

>:3prprrd techr)ical s

SefVICOS 8 October 1981 STAR ROUTE BOX 61 DRVEnPORT, LURSHinGTOO 99122 Energy Facility Siting Council Labor & Industries Building (509) 725-6666 Salem, Oregon 97310

-SUBJECT

WIND ANALYSIS OF TROJAN FINAL SAFETY ANALYSIS REPORT (FSAR)'

FOR

Inclusion in pre-meeting packet for 19 October 1981.

"The Trojan Nuclear Plant is designed to withstand the effects of a design basis wind or tornado without loss of capability of the safety systems to perform their safety functions [FSAR, p. 3.3-1]."

The FSAR design basis wind is 105-mph and has a recurrence interval of 100 years [FSAR, p. 3.3-1].

This implies one chance in three that the oesign wind will be exceeded during the 40-year plant lifetime.

The FSAR reference for design basis wind [H.C.S. Thom, "New Distribution of Extrene Wir.cs," ASCE] provides design basis wind speeds at site for recurrence intervals waich are normally considered for nuclear power plant safety.

For exanple, the 10,000-year wind at site is about 225-mph [Thom, from Fig. 6]. This is more than twice the design wind speed actually used in the Trojan FSAR.

These are "houriy" wind speeds. The structures must be designed to withstand gusts. The FSAR e7 ploys a gust factor of 1.1, based on an ASCE reference published in 1961 [FSAR, p. 3.321]. However, the 1968 ASCE reference [Thom] suggests a gust factor of 1.3.

Thus, design wind speeds for Trojan are under-rated about 15% according to the FSAR's most recent ASCE reference.

In short, Trojan is designec for a wind gust of 116-mph. This compares with the design. gust of 292-mph for the site, with a recurrence interval of 10,000 years.

Section 3.3.2 of the FSAR deals with tornadoes. That analysis shows that "a number of" plant structures can withstand tornadoes up to 300-mph.

In order to obtain that deaonstration, the following important assumptions were made [FSAR, p. 3.3-2 to 3.3-4]:

(1) The load is static. That is, the tornado is not moving..This' assumption permits dynamic loads to be ignored.

g rp N1.1Jb j~

Tt

\\

-J pp[

9-;

OCTI 51981= -

58g

u. gg t

l54MTelag=

o pp

WIND ANALYSIS OF TROJAN FINAL SAFETY ANALYSIS REPORT (FSAR) 8 October 1981 PAGE TWO (2) The tornado-induced pressure differential is applied very slowly -- 1.0 psig/second. That is, the tornado is not moving rapidly. This assumption permits the usual problem 1.

of exploding structures upon tornado-impact to be nearly ignored.

These assumptions are not valid for real tornadoes. The desf5n basis tornado is a " static" tornaco. Real tornadoes produce large oynamic loads. Real tornadoes have pressure-differential times which are a fraction of a second, rather than the 3-second time used in the FSAR.

Thus, real tornadoes are many times worse than the design basis tornado.

Even with the unrealistic assumptions of the design basis tornado, the following safety-related equipment is specifically not listed in the FSAR as fully protected against the 300-mph design basis tornaco [ comparing pp. 3.3-2 and 3.3-3]:

Control building belaw the cable-spreading room.

Diesel generator rooms.

Switchgear rooms.

Auxiliary pump room and Turbine Building.

Auxiliary and Fuel Building above grade.

That is, the FSAR documents lack of full protection of safety-related equipent from even an unrealistically mild tornado. This lack of protaction appears to imply potential loss of on-site power, among other important losses. This is understood to imply.a potential for core meltdown..

\\

~

Compare the results of tilis analysis with the overview statement b

from the FSAR, which began this analysis.

Submitted by.

SEARCH Technical Services lNormanBuske w -

w Analyst U.S. Nuclear Regulatory Commission, Washington, DC 20555.

(

Bart D. Withers, PGE,121 SW Salmon Street, Portland, OR 97204.

Karen Steingart, PSR, 7006 SW Fourth Avenue, Portland, OR 97219.

i Eugene Rosolie, Coalition for Safe Power, 408 SW Second Avenue, Portland, OR 97204.

I SERRCH.

.