ML20151T764

Safety Evaluation Supporting Amend 106 to License DPR-61

ML20151T764
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	08/09/1988
From:	Office of Nuclear Reactor Regulation
To:
Shared Package
ML20151T752	List: ML20151T751 ML20151T755 ML20151T764
References
NUDOCS 8808170249
Download: ML20151T764 (6)

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1. o,, UNITED STATES

!. a NUCLEAR REGULATORY COMMISSION

7. j WASHINGTON D C 20656

's,...../'SAFETYEVALUATIONBY_THEOFFICEOFNUCLEARREACTORREGULATIO RELAT,Ep,_TOAMENDMENTNO.106 TO FACILITY OPERATING LICENSE NO. DPR-61 C0hhECTICUT YAhkEE ATOMIC POWER COMPANY HADOAM NECK PLANT DOCKET NO. 50-213

1. BACKGROUND The Connecticut Yankee Atomic Power Company (CYAPCO), the licensee, and the staff have discussed the issue of environmental qualification of certain equipment and the mitigation of high energy line break (HELB) accidentsoutsidecontainment(Reference 1). Pursuant to 10 CFR 50.90 the licensee proposed to amend the Operating License by incorporating changes into the plant Technical Specifici; ions (Reference 2). The proposed change revises Technical Specification 4.12, High Energy Piping System, by expand-ing the augmented inservice inspection (ISI) program to include break locations on steam supply lines to the auxiliary feedwater (AFW) pumps.

The licensee provided changes to and clarifying information in Reference 3.

The staff concluded in Referente 1 that the proposed augmented inservice inspection for the auxiliary steam supply lines would meet all applicable regulatory criteria and would resolve all staff concerns associated with environment qualification and HELB issues for the Haddam Neck Plant. The staff also concluded that implementation of the updated program would pro-vide reasonable assurance of the continued integrity of the high energy piping and breaks need not be postulated at the monitored locations as part of HELB licensing basis. The objective of this Safety Evaluation is to review the Referenced submittals provided by CYAPCO.

!!. SUMARY OF INFORMATION The licensee fonaalized the conceptual resolution with the subject proposed license amendment. The AFV pump steam supply piping contains 47 welds based p PDC

i on a walkdown of the piping with the insulation removed during the 1987 refueling outage. The licensee provided an updated drawing showing these additional welds, A revised table describes the location, piping configur-ation, nominal size and method of inspection of welds included in the aug-mented ISI program. Based on the examination results from the 1987 refueling outage the licensee provided the following clarifications:

1) First Ten Year Inspection Program.

The Hadd0m Neck Technical Specification Section 4.12, which governs the augmented ISI program, specifically requires nondestructive exami-nation (NDE) of the subject piping during every 31/3 year period for the first 10-year interval. This is consistent with tr,e previously approved augmented ISI program governing the main steam and feedwater piping. The Haddam Neck ISI work plan has been modified to reflect this requirement.

2) Type of Inspection --Volumetric and Surface.

L The augmented ISI program for high energy piping systems is being performed in accordance with ASME SJction XI requirements, which defines NDE techniques, examination requirements, and acceptance criteria for each item being inspected. Under the requirements of ASME Section XI, Class 2 piping that is less than or equal to 1/2 inch nominal wall thickness only requires a surface examination. The augmented inspection program for the main steam drain (MSD) system requires that a volumetric and surface examination be performed where practical /possible. The NSD system piping is all less than 1/2 inch nominal thickness and a surface examination would fulfill the require-ments of Section XI. However, a volumetric (ultrasonic) examination is  !

being performed as a best effort examination in order to increase the level of confidence in the integrity of the piping. This is being done in spite of the piping sizes, gecmetric configuration of the ,

welds, and the as-welded surface conditions.  !

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-3 A surface examination was performed on each of the 47 welds. An attempt was also made to perform a full volumetric ultrasonic examination on each of the welds. However, the ultrasonic examination could not be performed on two of the welds (#28 and #47) which have geometric con-figurations which physically prevent an ultrasonic examination. A circumferential scan was performed on only five (5) welds of the re-maining welds because the small pipe radius causes the transducer to lift off the surface. Each of the 45 welds received an axial scan to identify circumferential indications. The scans were limited to the pipe side of the welds in most instances and the extrados of the elbow.

A 45" skewing technique was used to identify axial indications and replaced the circumferential scan which is difficult to perform on small-bore piping.

ASME Section XI requires that the ultrasonic technique examine the lower 1/3 of the weld and its heat affected zone (HAZ). The techni-ques used for the MSD piping examined the entire weld volume and its HAZ. Also, to increase the scanning sensitivity, the calibration technique uses a 1/32 inch side drilled hole reflector versus the ASME 5ection XI required 10 percent of the thickness notch reflector.

The ultrasonic examination performed on the MSD piping goes beyond the ASME Section XI requirements and a level of confidence of dpproxi-mately 90 percent has been achieved to ensure the piping structural integrity.

Monthly Inspection The license amendment requires a monthly visual examination of each weld. CYAPCO plans to walk down the piping without removing the lagging to perform the monthly visual examination. This piping con-sists of 3" and 4" piping which taps off the 24" mair steam lines and provides steam to the Terry turbines which in turn drive the AFW pumps.

An augmented ISI program already exists as a method of precluding the postulation of a rupture in the 24" main steam lines and the 12" feed-

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water lines. The proposed inclusion of this small bore piping does not change the method of inspection which has been in effect for the past ten years.

The main steam lines, as well as the subject small-bore piping, are maintained at a temperature of 500*F and a pressure of 900 psig when in operation. Under these conditions, a leak in the piping will become obvious, despite the fact that the insulation will remain on the piping.

Steam or dripping water will be noted by the operators during the visual inspections inside the Terry Turbine Building once per shift as part of the normal plant walkdowns.

III. STAFF EVALUATION The staff has reviewed the information in the Referenced documents. The existing augmented ISI program applies to certain welds in the main steam and feedwater systems. The proposed additional weld locations are contained in 26", 3" and 4" pipe systems with nominal wall thicknesses of .276",

.300" and .337", respectively. The licensee has attempted a full volumetric ultrasonic examination on each weld in the program and has identified the limitations to examination resulting from the existing design, geometry and materials of construction. The geometric condition prevented an ultra-sonic examination of two welds: #28, a pipe to flange weld and #47, a reducer to valve weld. The volumetric examination of other welds could be performed only from the pipe side of welds to fittings. The as-welded profile of most of the welds precludes effective examination from the weld crown for reflectors transverse to the weld. A 45' skewing technique was substituted for the detection of axial reflectors.

5-The objective of the proposed revision to Technical Specification 4.12 is to provide assurance of the continued integrity of the rain steam, feedwater, and steam supply to auxiliary feedwater system piping welds, identified in Tables 4.12-1 and 4.12-P. The staff has detemined that the limitations to inspection reported by the licensee are typical of constraints to ultrasonic e> amination of spall dianeter, thin-walled piping systems. Since the Haddam Peck Plant was built prior to adoption of ASPE Section XI, complete acces-sibility for inspection was not provided during the original plant design to the extent required by the current Code. The basis for Technical Specifica-tien 4.12 is that inspecticns will be conducted to the extent practical within the liniitations of design, geonetry and naterials of construction of the components. The staff finds that proposed augmented ISI program on the steam supply lires to the auxiliary feedwater pumps will exceed the extent and frequency of exan:inations required for these welds by the current edition of ASPE Section XI. The staff finds that the proposed addition of welds represents a program that is equivalent or superior to the existing augmented inservice inspection program. Based on the above, the staff concludes that the implenentation of the augrented ISI for the AFW piping will provide reasonable assurance of continued integrity of the AFW high energy piping.

Therefore, because breaks in the AFW piping at the monitored locations no longer need to be postulated, all issues regarding environnental qualifica-tion of certain equipment affected by AFW line breaks ud the mitigation of HELB accidents outside containnent are resolved.

IV. ENVIRChPENTAL CONSIDERATION This amendnent changes a requirenant with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The staff has detemined that the anendment involves no significant increase in the arounts, and no significant change in the types, of any effluents that inay be released offsite, and that there is no significant increase in individual or curulative occupational radiation exposure. The Conrissien has previously published a proposed finding that the anendnent involves no significant hazards consideration and there has l

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been no public comment on such finding. Accordingly, the amendoent meets the eligibility criteria for categorical exclusion set forth in 10 CFR 651.22(c)(9). Pursuant to 10 CFR 651.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendment.

V. CONCLUSION We have concluded, based un the considerations discussed above, that (1) there is reasonable assurance that the health end safety of the public will not be endangered by operation in the proposed manner, and (2) such activities will be conducted in compliance with the Commission's regulations, and the issuance of the amendment will not be inimical to the commun defense and security or to the health and safety of the public.

4 Dated: August 9, 1988 '

Principal Contributor: M. Hum I

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