SNRC-2180, Forwards 940829 Memo Entitled, Technical Evaluation of Dusting from Concrete Blocks, Addressing Issue Discussed in Insp Rept 50-332/94-02

Forwards 940829 Memo Entitled, Technical Evaluation of Dusting from Concrete Blocks, Addressing Issue Discussed in Insp Rept 50-332/94-02

ML20072P995
Person / Time
Site:	Shoreham File:Long Island Lighting Company icon.png
Issue date:	09/01/1994
From:	Bortz A LONG ISLAND POWER AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LSNRC-2180, NUDOCS 9409090050
Download: ML20072P995 (3)

Text

+ Long Shoreham Nuclear Power Station

, f. Island P.O. Box 628 l

/ Power North Country Road Y Autnanty Wading River, N.Y.11792 SEP 011994 l LSNRC-2180 <

l U.S. Nuclear Regulatory Coramission Document Control Desk Washington, DC 20555  ;

i Shoreham Decommissioning Project Dusting Potential from Concrete Blocks  :

Shoreham Nuclear Power Station l Docket No. 50-322

Reference:

(1) USNRC letter, James H. Joyner (USNRC, Region 1) to Arthur .1 l Bortz (LIPA), dated July 15,1994; subject: NRC Inspection No.

50-322/94-02 Ladies and Gentlemen:

The NRC Inspection Report No. 50-322/94-02 refers to the discussions between the NRC and LIPA concerning the potential for the dusting of concrete blocks left in storage (Reference 1).

As you requested, enclosed is a LlPA memorandum entitled, " Technical Evaluation of Dusting from Concrete Blocks", dated August 29,1994, which addresses this issue.

Please do not hesitate to contact me if there are additional questions or if further information is required in this matter. l Very truly yours, A. J. Bortz fvA8 Resident Manager

Enclosures:

(1) LIPA Memorandum, " Technical Evaluation of Dusting Potential from Concrete Blocks" cc: L. Bell C. L. Pittiglio T. T. Martin R. Nimitz D. Fauver R. Bernero 9409090050 940901 (p PDR ADOCK 05000322 O PDR 'gi

August 29,1994 MEMORANDUM To: Survey Unit File, RWO73 From: M. P. Tucker Termination Survey Section Head

Subject:

Technical Evaluation of Dustino Potential from Concrete Blocks

Reference:

(1) USNRC letter, James H. Joyner (USNRC, Region 1) to Arthur J.

Bortz (LIPA), dated July 15,1994; subject: NRC Inspection No.

50-322/94-02 j (2) USNRC letter, Clayton L. Pittiglio, Jr. (USNRC/NMSS) to Arthur J.

l Bortz (LIPA), dated June 7,1994; subject: Approval of a I Modification of Facility Release Criteria for Tritium and Iron-55 Surface Contamination at Shoreham Nuclear Station, Unit 1 As noted in Reference 1, LIPA has previously discussed with the NRC the potential for concrete left in storage to " dust". This concern was raised to ensure the NRC and LIPA were on common ground as to expectations on the final condition of the Shoreham facility at license termination. In discussions, LIPA agreed to perform a l technical evaluation of the issue, which is the subject of this memorandum.

After due consideration, LIPA has found no reasonable model which might be applied to estimate the amount or extent of dusting which could potentially occur as a result of long term storage of concrete blocks on the facility. The concrete blocks in question are those which are the remnants of the biological shield wall disassembly and are currently stored in the upper elevation of the Radwaste Building. The final l termination survey has been completed in this area and includes extensive surveys of the concrete blocks. These surveys demonstrate that the blocks are below the established criteria for release for unrestricted use.

As a means of evaluating the potential for dusting, LIPA has conducted a followup survey of the concrete. This survey was performed some 11 weeks after the initial survey, which is reported in the final termination survey. The results of the subsequent survey clearly demonstrate no increase in removable contamination on the blocks in the intervening weeks. Although, it is not possible to extrapolate this result to any definite time period, the subsequent survey clearly establishes a baseline of data which gives little cause for concern. There is no indication the dusting of the concrete surfaces will substantially alter the detectable levels of removable contamination which are presently being reported in LIPA's final survey report.

This issue has also been discussed with the NRC staff where it was stated that the i

I e

• potential fordisbursement of residual contamination was taken into account when the NRC approved and established the current criteria for release for unrestricted use. The limits of Regulatory Guide 1.86, Table 1 for total and removable beta-gamma  :

contamination have been adopted by LIPA for purposes of demonstrating the facility is suitable for release for unrestricted use. Therefore,it can be assumed that provided LIPA establishes that final residual contamination levels are at or below these  ;

approved levels, any potential redistribution of contamination would be within the l

, bounds of the NRC safety analysis which established the limits.

LIPA has reported removable contamination on the concrete with a maximum level of l

570 dpm/100 cm 2, after adjustments to account for the undetected presence of Iron-

55. While this compares favorably with the allowable level of 1,000 dpm/100 cm2 l specified by Regulatory Guide 1.86, it is noteworthy that over 90 percent of the reported activity is attributed to the presence of Iron-55. The NRC has previously l acknowledged the small dose consequence of surface contamination due to Iron-55 i (SECY-94-145) and, as a result, has modified the release criterion for total surface contamination due to Iron-55 from 5,000 dpm/100 cm2 to 200,000 dpm/100 cm 2 (Reference 2). This is an increase by a factor of 40 which directly reflects the minimal dose consequence of residual fron-55 contamination. If this same factor were applied to the release criterion for removable contamination, the resultant limit would be 2

l 40,000 dpm/100 cm . By this, it can be readily determined that the residual i removable contamination reported on the concrete is far below any level of concern.

( if potential dusting were to be of concern, such dusting would need to occur in such

! magnitude as to be almost physically impossible. The dusting would need to be l accompanied by some form of concentrating mechanism in order to establlsh removable contamination levels of any real concern. Here again, no model for this l physical action can presently be identified.

1 Therefore it is reasonable to conclude that the application of current release criteria j to the concrete blocks is adequate to ensure the health and safety of the general j public under conditions where the Shoreham facility is released for unrestricted use. l No additional measures appear necessary or appropriate.

MEJA-.-

Michel P. Tucker Termination Survey Section Head l MPT/mpt

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