IR 05000245/1996001

Corrected Insp Rept 50-245/96-01 on 960216-17.Violation Noted.Major Areas Inspected:Ultrasonic Insp for Intergranular Stress Corrosion Cracking in ASME Class 1 & Class 2 Nuclear Piping

ML20138G264
Person / Time
Site:	Millstone
Issue date:	02/27/1996
From:	Modes M, Peterson P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20138G250	List: IR 05000245/1996001 ML20138G245
References
50-245-96-01, 50-245-96-1, NUDOCS 9610210096
Download: ML20138G264 (3)

Text

'

.

-

.

.

U. S. NUCLEAR REGULATORY COMMISSION REGION 1 DOCKET / REPORT NOS:

50-245/96-01 LICENSEE:

Northeast Nuclear Energy Company Waterford, Connecticut 06385 FACILITY:

Millstone Unit 1 LOCATED AT:

Niantic, Connecticut INSPECTION DATES:

February 16-17, 1996 INSPECTOR:

A 1 - '.

N 2/27NL

.. itrick M. Peterson, NDE Technician Da'tS P

"~

Civil, Mechanical, Materials and Engineering Branch j

Division of Reactor Safety j

,

q APPROVED BY:

2 d7 70

Michael C. Modes, Chief Date

!

Civil, Mechanical, Materials and j

Engineering Branch

!

!

Division of Reactor Safety AREAS INSPECTED: An announced inspection of the ultrasonic inspection for intergranular stress corrosion cracking in ASME Class 1 and Class 2 nuclear

.

l piping.

!

l

9610210096 961011 PDR ADOCK 05000245

PDR

.

_

.-

._

_

.

!

.

REPORT DETAILS FOR MILLSTONE UNIT 1 INSPECTION REPORT NO. 50 245/96-01 1.3.4.1 PURPOSE

'

The purpose of this inspection is to compare the intergranular stress corrosion cracking

(IGSCC) ultrasonic (UT) signal response, using standard UT techniques of 45 and 60 shear wave, and the specialized 70 longitudinal wave (LW) technique. The intent of this inspection is to also verify IGSCC indications that can be detected, using both the standard

and LW UT techniques. Northeast Utilities Procedure NU-LW 1 describes the application of

'

LW technique, MP-UT-2, describes the standard techniques.

1.3.4.2 INSPECTION This inspection included a review of UT data packages from past and current outages.

'

included in this review are packages from the recirculation (RC) and low pressure coolant injection (LPCI) systems. The following is a list of the packages reviewed by the NRC:

RCAJ 2, RCAJ-5, RCAJ-8, RCAJ-10, RCAJ-12, CCBJ-11, CCBJ-12, CCBJ-13, CCAJ-4

.

To verify the licensees examination results, four LPCI welds were independently examined by the NRC. The UT instrument for this examination was calibrated, using Millstone

'

calibration blocks and Procedures NU-LW-1 and MP-UT-2. The NRC inspector compared the UT signal response from IGSCC and geometric indications, using standard UT techniques and the specialized LW technique.

j l.3.4.3 CONCLUSIONS

In four out of the five RC data packages reviewed by the NRC, the cognizant UT LevelIll had overturned the evaluation of the UT Level 11 examiner. The UT Level 11 recorded IGSCC indications and geometric indications. The Level lli evaluation determined the indications are geometric. In one example, the 1989 data package for RCAJ-5, nine indications were

,

recorded as IGSCC cracks, with axial components. The Level ill reevaluated the indications and determined them to be geometry, as documented on the Indication Resolution Sheet, therefore, returning component to service without an engineering evaluation. In 1995, RCAJ-5 was reexamined, and the original nine indications were found

to be IGSCC.

,

I IGSCC is detectable, using the standard technique, MP-UT-2, as well as the LW technique, NU-LW-1. How3ver, the standard technique is more susceptible to geometric reflectors, making the tvaluation more difficult. IGSCC is found in the heat-affected zone of the

,

weld. In many cases, the UT response from the geometric reflectors (root and counterbore) can mask the response from IGSCC. The LW technique is less susceptible

.

due to the 70 inspection angle.

Within the expected tolerances and variations, the licensees examination results for the

-

four LPCI welds matched favorably to those of the NRC independent examination _ _ _ _ _

. _. _

. _.. _ _ _ _ _ _ _ _ _ _ _ _ _ _. _ _.

_ _.

__

_

_ _. _

-._

_

_

a

,

e

At the conclusion of this inspection, the licensee had not determined the population of the j

documented cases in which the Level 111 overturned the Level ll evaluation of lGSCC indications and returned the components to service without engineering evaluation, a

The licensee had not determined if the welds, which leaked, were originally identified as having IGSCC, but overturned by the Level lli.

j The NRC inspector was unable to determine if the Level lli was qualified to the EPRI Guideline for IGSCC to make the evaluation and were the EPRI recommended techniques used to make the evaluation.

PERSONS CONTACTED

The following individuals were contacted during this inspection:

Northeast Utilities Energy Company R. Pfannenstiel, NDE Level lil S. Sikorski, NDE Engineer S. DuPlantis, NDE Level 11 D. Marris, Senior Licensing Engineer J. Cirilli, Senior Engineer J. Quinn, Engineering Supervisor, Tech Support, Unit 1 T. Schaffer, Manager Engineering l

.

. - - =

--