ML19256D170
| ML19256D170 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/28/1967 |
| From: | Fairtile M US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Long C US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7910170670 | |
| Download: ML19256D170 (3) | |
Text
.
a, 300R ORGINAL Charlas G. Long, Chief Rasetor Projects Branch f3, DEL Juif 23,1967 THRU:
R. C. DeYoung, Chief &
Comeni===nt & Components Taehanlogy Branch, DEL Morton B. Fairtile /p Containment & ^, --ts Tech =alagy Branch, DEL MITEOFOLITAM IDISCE - TRIEE MILE ISLAND - RESPONSE TO REQUEST OF JULY 10, 1967. ITIES 1.3, 2.1, and 2.2 C&cB: DEL:MBF IT 98
[0 M Item 1.3 - cantainment Issistion Valves.
3 1.
The==eandary steam line isolation system at Three Mila l
Island is superior to Duka/Oconee in that in addition to i
the C. E. turbine stop valves acting as one barrier and the etsam generator tubes acting as a second barrier, isolation valves esterior to coatminammt are supplied as a third barrier.
2 A review of SAR, Sectica 5.2 " Isolation System" for isola-tisa valve critaria uns cand=eted. Requirements for addi-e4 a==1 critaria, 4 =*1 =J 4 = the falleering, should be esasidered:
a.
Poser operated valves is isolation systems shall be
" fail safe".
h.
1Enare valves represent the only potential barrier between contain= ant atmosphere sad the public, utilize auto-matic actuation. A secondary mode of actuation shall be providad for the valves outside the e==mminnent barrier.
- e... ::Inte response times of valves =hm11 be specified.
d.
Protide missile protecties for all contain= set isola-ties valves.
a.
Yalves outside of *=t=4====t shall be a i==wi=um of 10 ft. from barrier.
1446 307 Item 2.1
" Steam Bubble" Problem The check valve, hinged disc, approach to tt "stema bubble" siphon break event appears on the basis of a pre 14=4n=vy review to be esp-able of centributina to eventual solution of this safety problem.
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?00R ORGINAL C. G. Long During normal reactor operation, the check valve in the proposed design will experience the following forces 3
1.
delta e = 60( - 555 = 48'F (inconsequential) 2.
Pressure per inch of valve perimeter 110
, g, (inconsequential)
,33 x 452 in
=
2 7T z 24 in.
lbs The 35 represents delta y es the oors and hasn't in been verified by flow testing yet; but is quoted by appli-esat in sepp. 5, page 5-1.
3.
INanaam vibratory forees tending to unseat the valve. These formee appear to be unconsequential but should be studied on B & V's 1/6 model.
4 Other forees and effects, such as aha=4a=1 attack, radiatise, dead lead etc., experieneed durins moraal operation any probably be negligible, ameopt in terme of the "self-weld" posaibility noted below.
The following factors should be censidered in the design of the system:
1.
Optiumn location - in same a dise separates from its hinges and drope between the thermal shield and pressure vessel.
2 Possibility of "self-welding" of disc to cora support shia1A under sembined effsets of 600*F temperature,15,800 lb fores, being===1ad for see year, sad radiation fields.
3.
The desige shocid allow inspection af the seat, both faces of the dise, the hinges sad repla w t of disc or hinge esapensats.
4 The five design problems pointed up in the DEL Report to the ACES dated July 6,1967, on Duke /Geenes (addendtic to Impet No. 2).
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- Iong 5 No Isas than two valves, each representing 100% of flow capacity, should be installed. m 24 inch sise was used here to compute forces only.
Item 2.2 - Accumuistor Spillanes_
There are two accumulator spillage possibilities, the first due to an.ase-1= tor pipe system bseak outsida of the reactor vessel, and the second due to an accumnalator discharge through a "short-circuit" path inside the reatter vessel sad them est through a ruptured cold les pipe.
The first possibility might be handled by desigsing each accumulator for 100% sapacity for the appropriate break size, h seeeed, and more severe probles, might occur during an HEA. In this event, system pressure blows down to 600 pai, the accumulator initiation point, in less than aina seconds (possibly in five seconds) and leaves the botten of the cars uncoveted. N high pressure water injection syatan is initiated at 1800 psi er within milliseconds af ter the assumed double ended rupture, if aermal power is availabla but may set estuallysstart for 10-15 see. (Fara. 6.1.3.2 of SAE), if a diesel start is required. la the time interval between initiation of assumulater discharge and receipt of H. P. injection coolant, the eere volume and eyper p1&aum area will be full ef steam. The acetsma-lator water will need to oversene signifiaant flow resistanea in order to pass through the sore. Besanse of pressure sodditions, the flow mi;ht "short-circuit" the intanded pr*h.-$4 leave the vessel j
via a ruptured sold leg without seeling er ret.svering e sore.
i h law pressure injection water would not be available until 25 seconds af tar vessel premeurs drops to 100 pani which is about 10 -
i 15 seconds after sa IOLA. James, " low preesce" flow is not avail-
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able for 35-40 seesada.
The fler rate of both R. P. yumpe is only sleet 700 gpa - thus the seenmalators delivering vatar to tha cora in the event of an M11A is vital to avoid a core meltdown, unless the : ore can rentin " dry" for up to 35 seemede.
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Distribt tion:
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