ML19206B149
| ML19206B149 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 03/16/1971 |
| From: | Case E US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Morris P US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 7905070488 | |
| Download: ML19206B149 (5) | |
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?'UR 16 '971 Peter A. Morris, Director Division of Reactor Licensing THM MILE ISLAND UNIT NO. 2, DOCKET NO. 50-320 Adequate responses to the enciesed request for additional infor-nacion are required before ve can complete our review of the subj ect application. These requests, prepared by the D'IS Str :ctural Engineering Branch, concern the Streesteel S/E Anchcrage Syste:n material presented in hiendment fil, Supple-ment #7 of the applicatien.
Oricin21 signed by E.G. Cue Edson G. Case, Director Division of Reactor Standards Enclosure Request for Additional Information for M #2 cc w/ encl:
S. Hzaznar. DR D. Skovholt, DEL R. Boyd, DRL
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THREE 't!LE ISLAND,UCLEAR STATION C:IT 2 Docket No. 50-320 A=end. 111. Suoni.
'7 - Stress t 2el S /H Anchcrane Svs te:
in order to evaluate the adacuacy of the properties of anchorage mate-rials, furnish soecifications API-5L, AISI 1117, and AISI 1040, to permit comparicon with AST:4 standards. Also indicate the =aterial specificaticas acclicable to the tendon ducts located in the walle and dcce.
(ref: S7-1-1) 2.
Since it appears that there is no field expericnce with regard to the K-Type slotted wedges, with saw-cut slots having sharp corners, provide inic=c-ir a the folicwing with resoect to this source of stress concentration:
(a) Potential increase with regard to possibility of corrosion of the wedges at the tips of the slots.
(b)
Behavior of the anchorage system if the wedges were to crack at the tip of the slot.
(ref. S7-2-1) 3.
- c. plain the plate cutting process described on p. S7-3-1 as follows:
(a)
Since fla:e cutting the periphery of large plates only minimizes notches, state to what degree these potential notches =ay initiate cracking or what o.her ceasures and controls will be applied to eliminate notches.
(b) Describe the = anne by which the process of trepanning holes in plates will assure c coth holes free of notches in the area of high stresses.
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. 4 Explain whether it is intended that naragrcph 2.2 on o.
57-3-2 with respect to quality ascurance of wed;c quality read, "'Jith the th re e si..dle drill, it is not,ossible to taka the vedte of f...
rather than ".
it _i_s c.ossible.
," which does no: appeae to be censistent with the logic cf the discussion.
5.
Sinca it is noted en page S7-3-3 that " Preservative is apolied as required," describe under what circu=s tances it would not be required to protect the anchorete hardware, and furnish a justificaticn.
6.
The galvanizing noted on page S7-3-4 =ay in sc=e cases facilitate corrosien, esnecially when galvanized and ncn-galvanized steels are used si=ultanscusly. Describe hcw this corresion potential is handled, or if other =easures are intended to centrol the conditicas under which corrosion may be avoided or =inimized.
7.
Describe what evidence or experience exists, and what quality centrol ceasures will be e= ployed, to assure that the grout will penetrate the interstices between the wedge and the stand and all s=all coenir,s in the wedges. (ref. S 7-5-3)
S.
The discussion en page S7-5-4 en hydrogen e= brittle =ent concludes that the alkaline enviren=ent will preclude such e= brittle =ent frc=
developing. Mcwever, two recently published docu=ents indicate that R
General Report en Corrosien of Prestressine Steel by Prof. Dr. Ing. G. Reht,
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FIP Sy=pesiu= on Steel br Prestressing, Madrid, 1963, pp. 9-13.
Highvay Research Scard, Rcport g90, " Protection cf Steel in Prestressed concrete Eridves, 19 70, p. 20.
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- the susceptibility of prestressing steel to hydrozen embrittlement in highly alkalir.e concret2 is a potential crobier.
E::rlain, in the li;ht of these rcierences, your bases and submit any addi:icnal data which supacr:s ycur stateren tha the alkaline envirennent will prohibit hydrogen e: brit:lement.
Include also the consideration of the ef fects of sulphides and cracks in concrete and grout uhien becc=e exposed to the anbient enviren=ent.
9.
Reliance on H. 3. Robinsen plant cencrete contain=ent cr:ck patterns in your resconse en p. S7-5-5 is not relevant for TMI v2.
Unless properly ccatrolled, unacceptable cracks can for= in the buttresses and ring girder under the bearing plates. Describe hev this cracking vill be centrolled.
10.
Expand tie answe: given en page S7-6-1 to include the consideration of the effect of the torsienal load generated en the anchcra;e by the induced twist in the strands in the design - the anchorage system and supporting concrete.
11.
The references to the H. B. Robinson plant, the Srenellis plant, and the Karachi plant, given en p. S7-7-1, are not relevant since a dif ferent prestressing system has been used en these projects. Des crib e the service expe:1ence available for tendens of the same system, of similar size and length.
In order to evaluate the grout capability to fill the voids and to perforn 1:s intended function precerly, cubri a discussien of the grouting procedure, especially with reference to:
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(1)
The methed used to cenitor the viscosity of the grout.
(2) The protection of the greuting eneratica frc= extreme envirca-
= ental conditicas.
(3) Whether the greutic: will be ene or tro-stage cceratica, and the respectivc groutinz pressure.
(4) Describe the previsions for ;rcut recirculatien.
(5)
Indicate all other provisions unich will be impic=ented to prevent clu=p for=cticn and block:ces of the ducts.
(re f. S 7-7-1,2, 3, 4).
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