ML19250C450
| ML19250C450 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 11/21/1979 |
| From: | Broehl D PORTLAND GENERAL ELECTRIC CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| TAC-07551, TAC-11299, TAC-7551, NUDOCS 7911260141 | |
| Download: ML19250C450 (19) | |
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... a November 21, 1979 Trojan Nuclear Plant Docket 50-344 License NPF-1 Director of Nuclear Reactor Regulation ATTN:
Mr. A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Dcar Sir:
Attached are 40 copies of Licensee's responses to several of the NRC Staff questions of September 19, September 28 and October 2,1979.
Sincerely,
' / A DJB/LWE/4sa6A24 Attachments c:
Mr. R. H. Engelken, Director l'. S Nuclear Regulatc ry Commission lj()q J.;
74 Region V Mr. Lynn Frank, Director State of Oregon Department of Energy
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NRC Ouestions (9/14/79)
O. 1/2 Page 1 of 2 1.
Provide a detailed description of how the equivalent dia-meter was determined which was used in computing the penetra-tion of the dropped washer into the steel cover plate for cable trays.
2.
Provide a drawing which illustrates the projected area used for computing the equivalent diameter.
Answer:
An evaluation of the postulated drop of a plate washer on the steel cover trays was provided in Licensee's response dated September 5, 1979 to Systems Branch Question No. 11.
In the equation used, the term "D"
is the diameter of the missile.
For an irregularly shaped missile, such as the corner of the plate washer, an equivalent diameter must be used in the analysis.
The equivalent diameter is taken as the diameter of a circle with an area (A) equal to the circumscribed contact area or projected frontal area of the noncylindrical missile.
(Refer-ence: page 2-4, Bechtel Topical Report BC-TOP-9A, Rev. 2).
The contact area (A) is the plate thickness (T) times the arc length (L) of the rounded portion of the plate washer.
The arc length (L) is the length of the rounded edge, or one I$?4 54I a
NRC Ouestions (9/14/79) 0.1/2 Page 2 of 2 fourth the circumference of a circle of that radius (R).
Plate Washer thickness (T) 2.375 in.
=
Radius of rounded corner (R) = 1.5 in.
L = 2n R = 2n (1. 5 ) = 2.36 in 4
4 5.6 in.2 A = TL = (2.375)(2.36)
=
D=
4A 4(5.6)
= 2.67 in, w
n The attached Fig. 2-1 shows the projected area used for compu-ting the equivalent diameter of the plate washer impact.
I394 342 O
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K PLATt WA6HE2
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WA6 HEE THICKhlESS T= 2.67i Pi2OJECTED /-)2EA 4
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FIGU2E 2-1
NRC Questions (9/14/79)
Q. 4 Page 1 of 4 For the cable trays ABA401, ABA010, and AEA380, which may be exposed to a drop of a plate washer in excess of 3 feet, you have stated that suitable guides or alterr; ate protection will be provided.
Describe the guides or alternate protec-tion and show pictorially how the protection will work.
Answer:
This answer discusses Mie methods which Licennee will use to assure that all cable trays in the Cable Spreading Room will be procected against any drop of a plate washer.
As indicated in Licensee's respo:.se dated September 5, 1979 to NRC Systems Branch Question No. 10(c), cable trays ABA401, TBA010, and ABA380 may be exposed to a drop of a plate wasner in excess of thr ee (3) feet.
If the present bolt hole locations were to be changed, cable trays ABA595, ABA285, or NPA206 penetrating the R line wall might also be exposed to such a drop. The cable trays located near the R line wall in the Cab;e Spreading Room which might be exposed to a drop of a plate washer while the washers are being installed on the R line wall are shown in attached Figures 4-1 and 4-2.
In order to provide protection to the cable trzyn passing through or near the R line wall which could be exposed to a drop of a plate washer, and to facilitate installa-tion of the plate washers, Bechtel plans to erect tubular scaffolding with nominal 2" thick timber planking in the Cable Spreading Room.
The scaf folding is E tandard construction equipment, and will be bolted together i394 344
NRC Questions (9/14/79)
Q. 4 Page 2 of 4 from 2-3 inch diameter steel pipes.
It is light weight mate-rial without sharp edges and does not present a risk of damage to either cables or cable trays.
As shown in Figures 4-1 and 4-2, the timber planking will be perpendicular to and flush against the wall directly beneath each applicable plate washer location.
It will be placed so that the maximum height a washer can fall onto it is 3 feet.
An on-site test will be performed by dropping a steel washer from 3 feet onto the planking.
If the washer penetrates, or significantly deforms, the planking, another layer will be added.
The planking will be cut to the length required to protect the cable trays below it.
Though for the most part the length of the planking will be seven feet, the maximum length in some instances will be determined by the space available.
In all cases the length of the planking will be sufficient to prevent a plate washer from falling more than 3 feet onto a cable tray.
The washers will be pulled across the floor of the Cable Spread-ing Room, and lifted onto the scaffolding.
The washers will not be lifted over cable trays unless the planking is in place and secured to protect the cable tray.
Any cable tray which could conceivably be struck by a washer dropped while it is being lifted to the scaffolding will be protected by the steel cable tray covers described in Licensee's response, dated Septemoer 5, 1979, to NRC Staff System Branch Question No. 11.
As discussed in that previous response, cable tray covers will l394 545
4 NRC Questions (9/14/79)
Q. 4 Page 3 of 4 protect the cables from a plate washer drop of less than three feet.
No plate washer will a s lif ted to the scaf folding in s
an area in which it is possible for it to fall more than three feet onto an adjacent cable tray.
After the plate washer is lif ted onto the planking, it will be pulled across the planking to the R line wall where it will be lif ted into position.
The protection provided by the scaffolding and planking, together with the cabic tray covers, assures that no unprotected cable tray will be exposEJ to the drop of a plate washer and that any such drop will be limited to 3 feet.
The scaf folding planks will be treated with the "Plamort-WC" fire retardant, as will be discussed in Licensee's response to NRC Staff Question No. 3, dated September 14, 1979. The amount of planking in the Cable Spreading Room at any one time during the modification work will be limited so that the resulting combustion loading in the room due to the plank-2 ing will be less than 1.0 lbs/f t compared with an existing 2
loading of 15.8 lbs/f t, (PGE-1012 Table 3-1).
At all times when the planking is in the cable Spreading Room, a fire watch will inspect the area on an hourly basis.
Protection will also be provided to the cable trays on the vest side of the R-line wall during the modification program.
Potential hazards to those cable trays includo dropped hand tools, bolts or nuts, and lumber cribbing for Plate 8 instal-q (a o
ng
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NRC Questions (9/14/79)
Q. 4 Page 4 of 4 I
lation*.
Field inspection has established that the maximum drop height for any of these items onto these cable trayt will not exceed 3 feet.
As explained in Licensee's redponse dated August 13, 1979 to NRC Staff Structural Branch Question No. 11 dated July 20, 1979,, cable tray covers will be used to protect the cable trays on the west side of the R line wall from tools and paterials to be used in that area.
Protection of the cable trays from fire hazards of cutting and welding is discussed in paragraph 6 of Affidavit of E. W.
Edwards, dated August 27, 1979, on Consolidated Inter-venors' Contentions Nos. 2A and C.
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NRC Questions (9/28/79) Q. 1 Verify that the installed Hexcel energy absorbing material will be (a) " stabilized" in order to ensure the edge material is stabilized and therefore will absorb the anticipated amount of energy should it be crushed by a falling plate. (b) "precrushed" in order to eliminate the peak load shown in Figure V-2 of Hexcel catalog #TSB-120. Answer: (a) The Hexcel energy absorbing material will be " stabilized" by bonding a plate on the top and bottom of the material. (b) The Hexcel energy absorbing material will be "precrushed" in order to eliminate the peak load shown in Figure V-2 of Hexcel catalog #TSB-120. I394 350
NRC Questions (9/28/79) Q. 2 Previous responses have indicated, in response to the control of dust, grit and debris, that the work area may be isolated. In this regard, the staff believes a small portable enclosure should be employed on the east and west inside walls of the Control Room and the electrical auxiliaries room when drilling holes in the walls. This box shall be capable of containing and collecting any dust, dirt, debris and water that may enter the room as the drill penetrates the wall. Verify that such a small enclosure and collection means will be provided in order to preclude the release of this material inside the rooms. Answer: A small enclosure will be used on the inside of the walls as outlined in the above question. It will be constructed so as to collect and contain any dust, dirt, debris and water incidental to the drilling. It will also be constructed such that a workman can hold the enclosure against the wall with his hands, and at the same time be able to see the wall to determine when and where the drill bit is penetrating. The enclosure will have approximate dimensions of l' x l' x 3" and will weigh approximately five (5) pounds. Such an enclosure will not pose a threat to electrical cables or equipment in the event that the enclosure would be dropped. Additional measures to control dust, grit and debris are described in Licensee's response to Question No. 7 of this set. I394 351
NRC Questions (5,28/79) Q. 4 Page 1 of 2 The Trojan response of September 5, 1979 to Systems Branch question 10 is confusing in that it speaks of areas external to Category 1 equipment. The staff believes that a fire watch patrol should be established to perform hourly inspec-tions for areas where a fire could affect safety related cables or equipment in which non-fire retardant wood will be used for concrete forms or other purpcses. The person while assigned as a fire watch patrol should have no other duties. This fire watch patrol should be instituted when the non-fire retardant wood is taken into any of these areas and continue until it is removed. The fire watch patrol would not be necessary during the times when a continuous fire watch has been established in an area for other reasons. Identify each of the areas where such a fire watch patrol would be necessary to monitor for fires in areas where a fire could affect safety-related cables or equipment. Answer: ~ The intent of Licensee's response dated September 5, 1979, to Systems Branch Question No. 1G(i) was to indicate that, during the modification program describ?d in PGE-1020, Licensee will establish a fire watch patrol when wood, whether fire-retardant or not, is utilized in areas where a fire could affect safety-related cables or equipment. The fire watch patrol will per-form hourly inspections from the time any wood is brought into any such area until it is removed, and will not be assigned other duties. The areas where such a fire watch patrol might i394 352
NRC Questions (9/28/79) Q. 4 Page 2 of 2 be necessary will be identified in Licensee's response to NRC Question 3 dated September 14, 1979. 1394 353
NRC Ouestions (9/28/79) Q. 5 In reference to the construction noise levels in the control room, response 18 to the staff's July 20, 1979 questions, you indicated that "Should it be determined by the plant operator in the Control Room that excssive noise is being c'reated, lighter weight tools or other means of concrete removal will be employed". The staff believes it is essential that if either the NRC IE resident inspector or the plant operator should determine that excessive construction noise is being created, lighter weight tools or other means of concrete re-moval will be employed. Verify that the abov' "iditional control on control room noise is acceptable and will be complied with. Answer: In the event that either the NRC IE Resident Inspector or the Plant operator determines that excessive construction noise is being created, lighter weight tools or other means of concrete removal will be employed. 34 jSd ~
NRC Questions (9/28/79) Q. 6 Presently it is proposed to utilize a positive feed control drill on the east and west control building outer walls. Fur-ther a person will be stationed on the inside for the purpose of detecting when the wall has been penetrated and notifying the driller via radio communications or by sound or battery powered telephones. Describe and discuss any other additional measures that can and will be implemented to further provide assurance the drill will not be allowed to penetrate to such an extent as to damage equipment within, e.g., positive stops or a paint strip on the core drill to alert the driller that wall penetration is imminent. Answer: Conventional practice for such drilling operations includes the use of marking on the core drill so that the drill operator knows where his drill bit is located in relation to his planned penetration depth. Such a marking procedure will be used for all concrete or masonry core drilling required for the modifi-cation work. The type of marking used will be one that the drill operator can easily see while operating the drill. Either a tape or painted stripe is the method which we would plan to use. 1394 355
NRC Questions (10/2/79) Q. 9 Your June 29 response to question 3 and PGE-1020, Revision 2 indicates that the appropriate factor of safety for the Nel-son studs is 2. Your June 22 response to question 22 indi-cates that a factor of 3 was used in the design of the studs and, therefore, may be more appropriate. Clarify this apparent inconsistency. Answer: In PGE-1020 Section 3.2.4.3 and in Licensee's response dated June 29, 1979 to NRC Question No. 3, it is stated that the allowable design values for Nelson studs are one-half of the values given in Table 15 of the Nelson Division of TRW, Inc. publication, " Design Data 10 - Embedment Properties of Headed Studs". A justification for the allowable design values is presented in Licensee's response dated June 22, 1979 to NRC Question No. 7 Licensee's response dated June 22, 1979 to NRC Question No. 22 indicates that the maximum calculated forces on the studs are one-third of the values given in Table 15 of " Design Data 10 - Embedment Proper ties of Headed Studs';. Since the calculated forces are less than the allowables, the design of the studs is adequate. I$Y4 356
NRC Questions (10/2/79) Q. 16 Your July 10 response to question 13 indicates that the maximum vertical amplification factor is 16 percent while your September 5 response to question 15 indicates that it is 13 percent. Therefore, provide the correct maximum vertical amplification factor. Answer: Licensee's response dated July 10, 1979, to NRC Question No. 13 stated that the maximum vertical amplification factor is 16 percent. Licensee's response dated September 5, 1979, to NRC Question No. 15 states that "the dead load was reduced 13% to account for vertical motion". Thus, the 13% is the reduction in dead load, and is not a value for vertical amplification. I394 3S/ k i
~ NRC Questions (10/2/79) O. 18 In your September 5 responses to questions, the response to question 17 indicates that for the combination of dead, live and SSE loadings, the maximum allowable stress in bending and tension is limited to 0.9 fy and the maximum allowable shear stress is limited to 0.5 fy. Verify that this limitation was imposed for the evaluations of steel elements discussed in the responses to questions 18 and 25. Answer: In Licensee's responses dated September 5, 1979 to Structural Branch Questions Nos. 18 and 25, the maximum allowable stress in bending and tension of the steel elements was limited to 0.9 f and the maximum allowable shear stress was limited y to 0.5 f for the load combinations referred to. y l394 358 .}}