ML19256D347
| ML19256D347 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/03/1970 |
| From: | Ross D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7910170851 | |
| Download: ML19256D347 (7) | |
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' ?;ve rle a r 3, 19 70 R. C. DeYoung, Assis tant Director, PWRs, DRL, !{
'7 711RL* : Charles G. Long, Chief, PUR-2, DEL ACCIDLST A'U. LYSIS FOR THi'IE MILE ISLAND (DOCRET 50-239)
The accident analysic section of cur draf t Interim Report on Thrau Mile Island las a discussion on the decontaminatien f actors required in order to just m:st Part 100 guidelines.
Recently (October 20, 1970) the Site, Environmental and Radiation Safety Croup released a ccmprehensiva avalua-tion of the E&W R&D efforts on the use of alkaline sodium thiosulf ate.
Cn the basis of that report, and related dose calculations, we are scheduling a meeting with Met-Ed (tentatively November 24).
Tne attach-ments to this memo outline the points we intend to discuss:
Table A - Acceptability of Alkaline Sodium Thiosulf ate Table B - Dose Calculations Table C - Possible Design Changes by Met *-Ed A meeting notice will be generated. We intend to pursue point 1 of Table C concerning leak rate reduction.
This implic, acceptability of 241 Rem as a 2-hour dose value; management concurrence is requested.
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Depwood F. Ross PWR Project Branch 2 Division of Reactor Licensing Enclos u res :
As stated ec:
P. A. Morris F. Schroeder 1454 336 T. R. Wilson P. W. Houe G. Burley 1,;.1,, [
I.,Spickler W. Nischan PWR Branch Chiefs D. F. Ross (3)
PWR-2 Readi.w.
Docket -
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A-1 TABLE A ACCEPTA3ILITl 0F ALKALINE SODIUM THICSULFATE Alkaline sodium thiosulf ate solutien is acceptable for use, provided th a t :
- 1.
"A pH monitoring system, designed to operate under post-LOCA condi-tiens, is available."
The Met-Ed sampling system is described in the FS4R, pp 9-11 through 9-13, and on Figure 9-7.
Samples can be taken f rom the discharge of either decay heat cooler (see the symbols CE-118 and CE-119 on Figures 9-7 or 9-10).
Remote sampling valves are provided.
It appears that, for the decay heat cooler samples, no isolation valve is automatically closed, as the sample point is already outside containment.
We do not know, and mus t dete rmine -
-Is pH conitorin~g equipment available at the sample sink, and can a sample of decay heat cooler outlet, with its ' load' of fission p'roducts, be handled?
2.
" Capability to replenish sodium hydroxide to' maintain a minimum solution pH of 8.0 should be required."
The Chemical Addition system is described in Section 9.2 of the FSAR (pp 9-8 through 9-11) and on Figures 9-4 and 9-5.
A caustic mix tank is provided for use with demineralizer regeneration and radwaste treatment. No apparent connection to the sodium
. ' hydroxide storage tank of the reactor building spray system is evi-dent. Therefore we must ask Met-Ed to describe (and provide) the
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1454 337
- Quotations denote the exact s tatements f rom the SERSG evaluation.
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A-2 means of refilli.ag the NaOH s torage tank (tank BS-T2; capacity
-12,750 gals with 20,500 lbs NaOH) within 7 days (arbitrary?) of its discharge during an accident.
3.
"Very s tringent limitations should be placed on the use of aluT.inum and all copper containing matericis which could come in contact with the spray or sump solution." ("Tae total weight of exposed aluminum should not exceed 300-500 lbs and the total amount of expcsed copper should be minima
')
In the TMI-l FSAR, Supplement No.1, Part I, pages 5-5 and 5-6 it is noted that there is only 54.1 lbs of exposed aluminum, but there is c significant amount of copper. The exposed copper con-
- sists of the polar crane pickup busses ~(162 ft ) and grounding cable
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9 (359 f t'). Met-Ed calculates that only 410 lbs of sodium thiosulf ate will be removed by copper reaction during the assumed 2-week spray operation. There is also 76,500 lb of copper in the reactor building cooler tubes. Met-Ed assumes that 10% of the spray drops get en t rained in the ducts, and the demister is 99% efficient.
The calculated thiosulfate consumptilon is 15 lbs.
We should inves tigate further:
How much exposed copper is reacted with if the sprays a:
run 90 days?
b.
Will the demister survive the initial pressure wave?
What are the tes t data supporting the.10% duct en trainment, c.
99% demister ef ficiency ' claims?
f d.
Is copper deterioration a common mode failure mechanism for the reactor building coolers?
In regard to the reactor building coolers we will soon ask for a summary of supporting test dcta and analyses.
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" Additional R&D should be required to adequately define the storage stability of the sodium thiosulf ate solution, or alternatively, a frequent inspection schedule shou 1d be i.mposed."
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In Supplement 1, Part I, page 5-5, Section 5. 3. 3, s torage s tcbili ty of thicsulf ate is discussed. On page 4-3, Section 4.3.2.6, it is stated that samples are perf odically taken from the borated watet s torage tank, the sodium hydroxide tank, and the sodium thio-sulfate tank. We will notify Met-Ed that the tech specs mus t contain a.
sampling frequency and methods b.
acceptable limits on the thiosulf ate available.
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f, c) roc the particalctes fccction 0.05 fractica ramaining - 0.03 (no removal)
Total remainin; 1, 2 hou rs = 0.113 + 0.070 t 0.05 = 0.233 Overall reductica f actor = 4.3 Tuc-hour doce = l'"00 7
321 rem.
=
4.3 Case 2.
IIEPA Filters (a) Organic fractign remaining 0.070 (as.in Case 1)
(b)
Inorganic and particulate f raction rer.:aining = 0.90 0.120
=
7.sc To tal f raction remaining =~ 0.07 + 0.12 = 0.19 Overall reduction factor = 5.2 1380 Two-hour dose = 5.2
= 267 rem.
Thus the c~onsequences are jus t over Part 100, without HEPA's, and jus t under, with HEPA's.
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-1 TJ. 2 C FOSSIll.1 CZ 'IG, C" J:G:S BY 'O-E" At present tha dose cansequence, (321 rem) are over Part 100 guidelines ant en ac ce p t ab le.
'e intcad *o discuss rcredul neasures with !!e t-Ed, f acluding.
1.
Redu; tion in lech rate.
The current leak rate is 0.2,' per day A reductica to 0.15; vould lowe r dose to 241 rer.
2.
Increasing the flow rate in the spray sys tem, or increasing t' e nurbe r o f sp ray pumps.
This is no t a verf promising area to pursue. The nutbcr of spray pumps (2) equals the nutber of diesels (2).
If additionci spray pumps were added, the postulation of one diesel f ailure could well bring the predicted performance back to the present valuc. On the other hand if all spray pumps worked, the delivery lines and nozzles would probably be under-designed. Wholesale design changes would probably be needed, and it is rath'r late for that.
3.
Installation of HEPA's, uhich eeu3 d lower the 2-hour dose to 267 rem.
The fan coolers are already designed; some ecdifica-tiens would be required. The fractional dose reduction, fron 321 rem to 267 rem (a change of -54 rem) seems small in ccm-parison to the dif ficulty and expense.
4.
Installation of charcoal filters inside centainment. The dose reduction has not yet been computed, but the final figure would be less than 267 rem, as liEPA's would be required in f ront of the charcoal.
1454 341
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3.
- 4e te o ro l e <'.z. We used TID e teo ro l:~_,-
(T_e 2 ', 1 :/s :,
uith buildia.7,.m.. e currection) in our calculations.
tie h".vc not comple tud o ur e tcorclo r revie*.',
_' the apolican t has not yet filed all of the onc i te re as u re:.en ts.
If the 2-hour s/Q cca be lessc.ec by 1/3, the 2-hour dose :.ill go fro: 321 ter to 214 re.a.
We will discuss these five alternati'ces 'eith Lt-Ed.
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O em" e
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