ML20212N612

Safety Evaluation of Util 840530 Response to Generic Ltr 84-11, Insp of BWR Stainless Steel Piping. Response Did Not Meet Requirements

ML20212N612
Person / Time
Site:	La Crosse File:Dairyland Power Cooperative icon.png
Issue date:	08/22/1986
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20212N463	List: ML20212N461 ML20212N612
References
GL-84-11, NUDOCS 8608290026
Download: ML20212N612 (2)

Text

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SAFETY EVAtVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATING TO DPC'S RESPONSE TO GENERIC LETTER 84-11

( DAIRYLAND POWER COOPERATIVE LA CROSSE ROILING WATER REACTOR (LACBWR) l DOCKET NO. 50-409 l

1.0 INTRODUCTION

l The Division of BWR Licensing has reviewed the submittal dated May 30, 1984 from Dairyland Power Cooperative (OPC) in response to Generic Letter 84-11 i regarding the stainless steel piping inspection plan at LACBWR. The staff l noted that LACBWR was not inspected under IE Bulletin 83-02, because its l recirculation pipir.g was made of carbon steel materials. However, LACBWR l does have nonconforming piping in other systems. Our ccmments to the proposed i piping inspection plan are provided below.

2.0 SCOPE OF PIPING INSPECTION The licensee proposed to follow the auomented inservice insoection program in Technical Specification (TS) 3.0.10(f), because the sub.iect procram was considered meeting the guidelines in Generic letter 84-11. TS 3.0.10(f) requires the examination of all nonconfirming service sensitive piping in each of the three consecutive 36-month intervals. LACBWR will start the second 36-month interval in 1985/1986 coinciding with the spring 1986 refueling outage.

The staff noted that DPC in an earlier submittal dated July 10, 1980 had classified several nonconfirming pipe lines in the decay heat, main steam and feedwater systems as nonservice sensitive and, therefore, those pipe lines were not included in the augmented inspection program of TS 3.0.10(f).

As a result of the issuance of Generic letter 84-11, the category of noncon-firming nonservice sensitive piping no longer exists, because all nonconforming piping are considered by NRC to be service sensitive. Therefore, those nonconforming piping lines, previously classified as nonservice sensitive, should be included in the augmented inspection program of TS 3.0.10(f).

3.0 LEAK DETECTION The unidentified reactor coolant leakage limit inside the containment is 1 gom at LACBWR which is more restrictive than the auomented leakage Ifmit of ? gpm increase in a 24-hour period. However, the benefit of this lower leakace limit is reduced, because the TS requires monitoring of the leakage only once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and also does not define an inoperability period for the sumo level and flow rate monitoring system. To ensure the timely detection of excessive leakage, we require that the guidelines in Attachment I to Generic Lettcr 8608290026 8608P2 9 DR ADOCK 0500'

84-11, particularly regarding the leakage monitoring frequency (once every 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />) and the inoperability period of the monitoring system (no more than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />), should be followed.

4.0 ULTRASONIC TESTING PERSONNEL Ultrasonic inspection results by the utilities have shown that'the performance by UT personnel qualified under IE Bulletin 83-02 lacks uniformity and consistency.

To resolve this concern, the NRC has determin'ed that all UT personnel performing detection and evaluation should be upgraded at the EPRI NDE Center. The staff suggests that DPC contact the EPRI NDE Center to arrange for a requalification of the UT personnel to be used for the IGSCC piping inspection.

5.0 ALLOWABLE FLAW SIZES FOR FLUX WELDS All shielded metal arc welds and submerged arc welds are classified as flux welds. Laboratory test data have shown that flux welds exhibit lower toughness in comparison with the welds fabricated by other conventional techniques. Therefore, the allowable flaw sizes for such welds in Code IWB-3640 are currently revised to take account of the low toughness. The revised Code IWB-3640 is expected to be published soon. Prior to the publication of the revised IWB-3640, the staff has developed interim guidelines in the use of IWR-3640 to derive the allowable flaw sizes for the flux welds. The key points of the staff interim guidelines are summarized below:

(a) The secondary stresses (mainly thermal stresses) should be included in calculation of the stress ratio.

(b) The flaw size limits for the flux welds are 2/3 of the Code IWB-3640 allowables at a stress ratio as modified by (a).

Principal Contributor: W. Koo Dated: August 22, 1986

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