ML20082E320

Responds to Notice of Deviation Noted in IE Insp on 830801-31.Corrective Actions:Concrete Samples Taken at End of Concrete Pump Discharge Line,Addl Lighting Installed & Number of Concrete Vibrators Increased

ML20082E320
Person / Time
Site:	Fort Saint Vrain
Issue date:	11/09/1983
From:	Brey H PUBLIC SERVICE CO. OF COLORADO
To:	Madsen G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
P-83357, TAC-55287, NUDOCS 8311280144
Download: ML20082E320 (4)

Text

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Publie service company e odermde o 2420 W. 26th Avenue, Suite 1000 Denver, Colorado 80211 /

November 9, 1983 Fort St. Vrain 0+ /

Unit No. 1

, P-83357

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Mr. G. L. Madsen, Chief h Reactor Project Branch 1 ]

U.S. Nuclear Regulatory Commission jL NOV211%3 Region IV 611 Ryan Plaza Drive, Suite 1000 h t W

! Arlington, Texas 76011

SUBJECT:

Notice of Deviation Building 10 Concrete

REFERENCE:

U.S. NRC Letter dated 10/12/83 Madsen to Lee (G-83368)

Gentlemen:

This letter is in response to the Notice of Deviation received as a result of an inspection conducted at Fort St. Vrain during the period

, August 1-31, 1983. The restatement of the deviation and the response to the items contained in the Notice of Deviation is hereby submitted.

NRC COM ENT The licensee has apparently deviated from good acceptable l construction practices fcr placement of concrete during placement j of Building 10-W-4800-6-015. Several examples are listed below:

a. ACI 304, Section 9.7 states, in part, "For pumped concrete, it frequently is desirable to sample at both the point of delivery to the pump and the point of discharge from the line and perform correlation testing to determine if any significant changes -in slump, air content, and other mix i characteristics are occurring."

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.. Contrary to the above, no correlation tests were taken at

- point of placement.

b. ACI 311 recommends: proper lighting and equipment for piscing

'of concrete.

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- Contrary to - the above, there was insufficient lighting for 4

- placement of concrete, and there were or:1y two vibrators

-available.

c. ACI 304, Section 10.2 recommends the so called " green cut" cleanup is a good method for preparing an inferior joint such as a cold joint.

Contrary to the above, the south ~ wall of. Building 10 contained a cold joint that was not discovered until the forms were removed.

The basis for the deviations' from. Specification 75-J-02 and

-ANSI 45.2.5 is because of the term "small . concrete quantities,"

as specified in the FSAR. "Small concrete quantities" is not clearly defined in the FSAR.

PSC RESPONSE ITEM a It has been PSC's normal practice to sample concrete at the

. point of discharge from a truck in order to have a standard basis for acceptance or. rejection for all . concrete for a projecc.

Section 9.7 of ACI 304 characterizes the double sampi Ing technique as being " desirable". In the particular case of Building 10, it was PSC's judgment that the concrete did not require double sampling to be performed.

PSC began taking concrete samples at the 'end of the concrete pump discharge line as requested by the NRC so that slump cad air

, content could be evaluated. This practice was started on

August 5, 1983 and continued for all remaining concrete l- placements for Building 10, in which pumped concrete was l' required.

ITEM b After the first concrete placement for the walls on Building 10, PSC took the following actions to correct the problem with

! - voids in the concrete: (1) Additional lighting was placed above *

! the wall forms so that the construction forces could more easily .

1. view the concrete during placement. (2) The number of concrete vibrators for use 'during . concrete placements was increased

- significantly. These corrective actions were in'effect for all

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P-83357 Paga 3 remaining Building 10 concrete placements, starting August 5,

, 1983.

e ITEM c The cold joints in the lower portion of the Building 10 walls were due to a truckload of concrete that was rejected for failure to meet specifications and the resultant time delay until another truckload of concrete could be delivered to the job site.

During the placement of concrete for the walls for Building 10, it was determined that a cold joint was. starting in the east wall therefore the " green cut" cleanup method was used prior to placing the remainder of concrete for the east wall of Building

10. However, during this same concrete placement for the walls of Building 10, there was no indication that a cold joint was developing in the south wall, and therefore no corrective measures were taken. Upon removal of the concrete forms, and the discovery of the cold joint, it was technically evaluated by PSC and found to be acceptable. The corrective measures as mentioned above that PSC put into effect prior to the next concrete placement prevented future problems of this type. The corrective measures were in effect starting August 5, 1983.

NRC COMMENT

- It is requested that upon response to this report that the licensee define "small quantities" of concrete.

PSC RESPONSE Prior to the construction of Building 10, a conversation was held with Mr. W. Dickerson, the former NRC Resident Site Inspector, to discuss the applicability of the FSAR requirements for small quantities of concrete to Building 10. It was agreed that the concrete required for Building 10 would be considered to i be a small quantity and that the FSAR requirements for concrete would apply. In the future we do not anticipate significant concrete work that would require an on site batch plant. On a project by project basis it will be determir.ed whether an on site concrete batch plant can be justified. If the on site batch plant cannot be justified, then the amount of concrete to be installed shall be defined as a small quantity. In either event

. the applicable standards and codes for concrete shall be l followed. ,

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b83357 Page 4 t

This completes the PSC action items required by the Reference ietter.

If you have any further questions, please contact Mr. J.R. Reesy

.- (303):571-8406.

Very truly yours.

• W H. L. Brey, Manager Nuclear Engineering Division HLB / RAG:pa l

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