ML20132B587

From kanterella
Jump to navigation Jump to search
Provides Preliminary Findings on Potential Spirit Lake Mudflow Impact on Columbia River & Facility.Lwa to Evaluate Assumptions in Original Mudflow Analysis Recommended
ML20132B587
Person / Time
Site: Trojan File:Portland General Electric icon.png
Issue date: 06/20/1983
From: Laird L
INTERIOR, DEPT. OF, GEOLOGICAL SURVEY
To: Ballard R
Office of Nuclear Reactor Regulation
Shared Package
ML20132B592 List:
References
FOIA-85-353 NUDOCS 8307060063
Download: ML20132B587 (3)
v • d • e


Text

p OEPARTMENT OF THE IN1ER10R q, , dr I'L

.- (,']_ GEOLOGICAL SURVEY , :/ ,

_l

, / 1

p .ater Fesources Division / , , " 'g ~.

[i i- 1201 Pacific Avenue - Suite 600 L,l' i Tacosa, Washington 98402 i

' June 20,1983

[.

i'

,I Mr. Ibnald L. Pallard, Ctief I Environ:: ectal & Hydrologic Ehgineering Branch Office of Wxlear Reactor kgulation U.S. Nuclear Regulatory Cbsmission Vashington, D.C. 20555 l'

Dear Mr. Ballards f'

Subject:

Freliminary findings on potential Spirit take sudflew impact on Coltabia River and Trojan Nxlear Plant y

b i As requested, we are furnishing you a brief sanary of our preli.11cary findings on the inact of a atdflow frca Spirit lake near M:unt St. relens en the

nojan nuclear pcwer facility. These findings are provisicnal and are subject
.. to rer.ev and apgoval of the Director of the Gological Servey and eterefcn I should not be released outside your agency.

L' As a result of these findings we reect.mnd that you approve se:e liaited wrk in Phase II of our criqinal proposal--to evaluate some of the assuspticas origi.

. ally sade in the sidflew analysis. W would propose to investigate further:

~

l, 1. Desosition of sediment from the sudflow during its ficv frcm spirit tala 5' to the south of the Cowlitz. Our original analysis carried ainest all of the entrained sediment to the south of the evlitz River. A sore realistic

. analysis--folleving the pttern of other stdflevs--wild be to do;os t prt of this sediaent in 'ponding' areas along the route of the ficv.

, this adjustant vill lessen the sedicent deposition in the ColcAia ind the calculated water level at Trojan.

l

2. Stepe of sediment deposits in the Coltr.bia River. Ceneral slope of :e.. .e .'

deposits upstrees of the Cowlitz follwing the ray 18-19.1980 zud!!cv 1 was about 2.5 feet per mile-*xceedingly flat s.6!n co.:parad to sbila:

flo'es. The gradient in the Cowlitz River ateve the toutte Rivar for L.x 1 we safflow was about 8 feet per sile. This stops of de;osit could have

, u apiceciable effect on backwter and the elevation at irojan--thus we believe this deserves additical analysis.

The above tw elements can be easily accomplished within the origim1 wrk plan and funding estiutes.

Sincer*!y. your 4

(rss,

! A L (5 daos D Wr- t . latrd

. strict c.i.f b 1

\

d. 01Cl4$1Nde

- -.. . m

., 1 l1  :

ggj PRELIMINARY FINDINGS IN TRGIAN STUDY, PHASE I, June 1983 Phase I of the sttdy was conducted by USGS for the Nuclear Regulatory C e__.ission. In Phase I a st2 flow as described in WRI Report 82-4125 was applied to the Columbia River, assming a ntaber of conditions for the mudflow, to determine potential flood elevations at the frojan Nuclear Powerplant. Several scenarios were assuted for conditions in the Q1utia River during and folleving the mudflow. The flood elevations wre deter-mined using the Central Purpose Dan-Break Flood Simulation Ibdel (K-634),

modified by L. Dekng (K-599), with the Collabia River at several different steady-state discharge magnitudes.

Clear Water Flow Evaluation

1. A Cowlitz stdflow flood, applied dth ' clear-water' friction and no
deposits in the Coltabia, did g produce peak elevations at Trojan in excess of 45'ft, which is the flood design elevation at Trojan
,
a. Peak at Trojan = 22 f t with Columbia at low flow
b. Peak at Trojan =,M ft with Columbia in 100-yr flood

. .L Mudflov - Sediment Deposit Impact Eva1tation

2. A Cowlit: audflow flood, with *zudflov* friction in the mirabia downstream from the Cbwlitz, ' clear-vater' friction up;trean, and no deposits cop exceed 45 ft at trojan during a concurrent eajor flood of the Columbia, but did_ not t exceed 45 f t during low flow, slack tide, or less severe (<50-yr) floods of the Cblumbia:  :

% \

a. Peak at Trojan = 31 ft with coltabia at low flow
b. Peak at Trojan = 44 ft with Colusbia in 10-yr flood l
c. Peak at trojan = 48 f t with m1mbia in 100-yr ficod t

94 .

i* 3. About 30 perce:t of t.he tudflew from th2 Cowlitz would travel upstrean in the coltebia if the Cbitabia were at low flow and slack tide, accor-

?-

ding to the routing sodel.

4. If 70 percent of the audflow moving upstreas were to deposit, the voltwe of the deposit would be 500 million cubic yards, asstning out of the Cowlitz a total solids voltae of 2.4 billion cubic yards and 30 percent of that was ' fines' remaining in suspension.
5. If the gradient of the deposit were -2.5 ft/mi. in the upstrean dire::-

tion, as occurred in May 1980, the elevation of the 500 Hyd3 deposit would be about 30 f t at the south of the Cowlitz and about 20 ft at Trojan. Steeper adverse gradients have been observed and, if they occurred, would produce higher deposit elevations.

i 6. itinter floods can occur on the Colt:abia within a few days of low ficvs.

l The peak of December 1964, discharge about 1 million efs and recurrence about 100 yr, followed within 3 days of a low flev.

7 A Coltabia vinter flood stbsequent to 500 Myd3 deposited epstream of the Cowlitz at a -2.5 f t/d gradient during (bitabia low flow could produce a peak elevation at Trojan in excess of 45 ft:

a. Peak at Trojan = 45 ft with Coltabia in 2-yr flood
b. Peak at trojan = 49 f t with Coltabia in 10-yr flood l c. Peak pt Trojan = 52 ft with Ositabia in 50-yr flood
8. The evidence from May-June 1980 indicates that a deposit, once estab-lished, may not be scoured appreciably in the short ters by clear-wat2r flow over the deposit.
9. The volt:me and slope of depsit upstreas from the Cowlit: are t.'w co.y trolling features for Trojan flood elevations.

' W , _ a.  ;. u ..+ M a. - -.a . y.  : w, .:~. - . .. ,. - .. ~~. ..:..-.i1

. , _ . .. ,.m. _- - .. ..-. - .. ..

.i p "* * %,

t UNITED STATES

.e. _ ,

f* NUCLEAR REGULATORY COMMisslON

[

1@ j .

WASHINGTON. D C. 20555 s ; . s., , / JUL 191983

Docket No.: 50-344

! MEMORANDUM FOR: Robert A. Clark, Chief

, Operating Reactor Branch No. 3

{ Division of Licensing i

THRU: William'.V. Johnston, Assistant Director Materials, Chemical and Environmental Technology Division of Engineering

~

?

FROM: Ronald L. Ballard, Chief Environmental and Hydrologic Engineering Branch Division of Engineering SU3 JECT: PORTLAND GENERAL ELECTRIC SPIRIT LAKE FAILURE

. EFFEr.TS ON TROJAN Plant Name: Trajan Decket Number: 50-344 The report dated Jdly 1,1983 from Portland General Electric (PGE) to you concerning flood potential at the Trojan site has been reviewed by the Hydrologic Engineering Section. We found that the report is defi-cient in several respects. The PGE repert seems also to be an abbre-viated version of a more detailed report from the consultant. If this is the case, it would be far more useful for us to work from the original report. We have prepared a set of questions to elicit further infor-mation of the licensee. We would like to have the PGE report reviewed by the USGS, who is performing an independent review, but no decision has yet been made on extension of their contract. This review has been conducted by R. Codell, with input from M. Fliegel and myself.

&WffY onald L. Ballard, Chief Environmental and Hydrologic Engineering Branch Division of Engineering Enc'csure-As stated of

- sa (y ')/ l r g gy ~

i

~ 'of R& ? TNY

--p----Mwp7 pr

j '

. _ . . - . - . . - - . = - - ..- - ~ - . - - - - a

. . . .- ~ - - ---- - --

! HYDROLOGIC ENGINEERING SECTION -

i i Additional Questions " Potential Mudflow from a Hypothetical Failure of Spirit Lake 1

Blockage" (July 1,1983 response from PGE) 4

1. The report appears to be a summary of a more detailed analysis and report.

i As such, however, it does not contain the information necessary to enable

us to evaluate it. If you have a more complete report please provide it.

~

2. The important case of a mudflow during a low Columbia River flowrate,

, with consequent high sedimentation in the Columbia River, followed by.

, a large flowrate has been neglected. . Records have shown that high flow-rates (1,000,000 CFS) have followed periods of low flow by only a few days.

Analyse the potential for flooding of the site by this scenario, or justify why this case was not considered. *

3. Item 1.3 The procedure used to reduce the sediment concentrations from 39, 52, and 65 percent to 20, 30, and 45 percent respectively, as summarized in Table 1 should be discussed and all assumptions should be justified.

For examole, what is the basis for reducing the volume of material into the Cowlitz by 40% (column 2)? What is the basis for the ratio of sand to finer material of 2 to 1 (columns 3 and 4)? Etc.

4 Item 1.4 Please explain the basis for the 30 percent moisture assumotion.

Is this figure based on available pore volume or on total volume of cry solid? What porosity was used and what is its basis?

5. Item 1.6 What is the basis for assuming a Columbia River sedim'ent concentration of 500 ppm? What effect would varying this concentration have on your results?
6. Several references are used in the text, but are not documented. For example, the "Colby method" in item 2.4 Provide the references.
7. Item 2.5 Define the term " bulk'ing Factor" 3
8. Item 2.6 Give basis for your assumptico that the shape of the mudflow sedi-ment deposit at the confluence of the Cow 11t: and Columbia rivers can be raticed from the configuration of the deposition following the May 18, 1980 mudfl ow. That mudflow deposition was rather flat compared to other known mudficw slopes. What is the sensitivety of your results to variations in the slope of deposited sediments?
9. Item 3.4 Give basis for calculations of sediment load. Were formulas employed derived from relationships for sediment transport in rivers?

If so, justify that these formulas are acceptable for the very-high sediment loads of the present case?

10. Item 3.8 Why is 400,000 CFS the "most reasonable Columbia River flow ,-

to evaluate"? Is there a probabilistic basis for this conclusion (e.g.,

NRC safety goal)?

--t --9___, , - y- -y-. y-w--

9

.-wn ... .- ... -

.. . . : ... ~ . -

. ..-... . -. _ . . _.. - . - ......~. - . -- .

f-l ;

i f!' '

l

11. Table 1
(a) Column 8 is unclear. I believe that the expression should
be (col 6 + col 4)/1.4. Explain the meaning of the value 1.4, and wny
- ' it is used here.

J (b) - Explain the difference between column 1 and 2. Al so, why is " material" used in column 1. and " sand, silt and clay" used in column 27 l

4 I

)

1 l

6th[ h 5

i J

s 4

- O, i

i

. .e-e p-3 awe.g.. m d4 e sesa-,see w , e e sesmoep*-*s.**-< *ts.**--me=us -e+- * + AA ***rrw '*Mw9'***- ** '*rd 4,n-- - , 4.-w--. - ,~- , _ _ - g--

y g --g ,

Retrieved from "https://kanterella.com/w/index.php?title=ML20132B587&oldid=2886295"