ML20044G696
| ML20044G696 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 05/25/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20044G695 | List: |
| References | |
| NUDOCS 9306040114 | |
| Download: ML20044G696 (4) | |
Text
,
Enclosure
/,c,....
%,(
UNITED STATES i
3.~
8" NUCLEAR REGULATORY COMMISSION g
4.y
.g WASHWGTON. D. C. 20555 j
a,
,f i
}
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RE00EST FOR RELIEF FROM REGULATORY RE0VIREMENTS ENTERGY OPERATIONS. INC.
GRAND GULF NUCLEAR STATION. UNIT 1 DOCKET NO. 50-416
1.0 INTRODUCTION
A The Technical Specifications for Grand Gulf Nuclear Station -(GGNS), Unit 1, state that the inservice inspection (ISI) and testing of the American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 components shall be
'l performed in accordance with Section XI of the ASME Boiler and Pressure Vessel-i Code and applicable Addenda as required by 10 CFR 50.55a(g), except where
~
specific written relief has been granted by the Commission pursuant to 10 CFR 50.55a(g)(6)(i).
Pursuant to 10 CFR 50.55a(g)(5)(iii), if the licensee determines that conformance with an inspection requirement of Section XI of the ASME Code is.
i not practical for its facility, information shall be submitted-to the' Commission in support of that determination and a request made for relief from the ASME Code requirement. After evaluation of the determination, pursuant to L
10 CFR 50.55a(g)(6)(i), the Commission may grant relief and may impose alternative requirements that are determined to be authorized by. law, will not i
endanger life or property or the common defense and-security and are
~l otherwise in the public interest, 'giving due consideration to the burden. upon i
the licensee that could result if the requirements were imposed.
By letter dated February 18, 1993, Entergy Operation, Inc. (the licensee),
I requested relief from certain examination requirements of ASME Section XI,'
1977 Edition, through and including the Summer 1979 Addenda, of.the ASME Code for the Grand Gulf Nuclear Station, Unit 1.
Additionally, the licensee proposes to amend the alternative testing section of the inservice inspection requirements'.
The licensee submitted ISI Relief Request No. I-00010, Revision 2, among others, in a letter dated May 24, 1988. The licensee also submitted ISI-1 Relief Request No I-00010 Revision 3, in a letter dated June 28, 1990.
The NRC staff's review and evaluation of Relief No I-00010, Revision 2 and 3, were-documented in letters to the licensee dated August 21, 1989, and October 16,
)
1990, respectively. Additionally, the licensee submitted Relief Request No. I-00010, Revision 4, dated July 31, 1991. The NRC staff's review and i
evaluation of Relief Request No. I-00010, Revision 4, are documented in a.
letter to the licensee dated March 10, 1992. Our evaluation and conclusion'
-for Relief No I-00010, Revision 5, are reported in this Safety Evaluation ~(SE).
l 9306040114 930525 PDR ADOCK 05000416:
'G PDR _
- a
2.0 EVALUATION Code Reouirement - Class I and Class 2 pressure retaining piping welds are required to be volumetrically and surface examined, essentially.100% of the weld, once every 10-year interval in accordance with ASME Section XI, t
Table IWB-2500-1, Category B-J, Table IWC-2500-1, Category C-F.
The Class 1 integral attachment. welds. depicted in Table 1 are required.to be surface examined once per 10-year interval in.accordance with ASME Section XI, Table
~
IWB-2500-1, Category B-K-1.
Lomponent - Inaccessible parts of ASME Code,Section II'I, Class '1 add 2:
,i pressure retaining and integral. attachment piping welds. The welds and systems are identified in Table 1 of your submittal. This revision adds-1 items 74 through 77. The limitation of inspections is due to portions of the welds that have physical obstruction due to design.
[
Relief Reauested - The accessibility of the welds for surface and volumetric examination is shown in Table 1.
The areas were determined during.preservice examination. The code requirements for 100% surface and volumetric examination are not practical.
dequest is made to perform the' surface and.
A volumetric examination as recorded in Table 1.
t Basis ~ for Relief - The licensee stated that the requested relief should be.
I granted for the following reasons:
i "1.
The inaccessible portions of listed pressure retaining welds were examined by radiography, passed in accordance with ASME Section III, Class 1 and 2 requirements.
1 2.
The inaccessible portions of the pressure retaining and' integral l
attachment welds were surface examined (magnetic particle or liquid penetrant), passed in accordance with ASME III and/or XI, Class 1 a
and Class 2 requirements.
,j 3.
The inaccessible portions of listed piping welds will be subject to.
j a system leakage test after each refueling outage for Class 1, and 1
each inspection period for Class'2 in.accor.ance with ASME Section d
+
XI requirements.
4.
The inaccessible portion of listed piping welds. will be ' subject to a system hydrostatic test each inspection interval in accordance with ASME Section XI, Class 1 and 2 requirements.
- l j,
5.
Accessible portions of listed welds will be volumetrically and surface examined each inspection interval in accordance with ASME Section XI. Should indications be found, an engineering evaluation l
will be made to determine if the inaccessible portions of the listed welds have been affected.
i i
l l
ll
6.
Leak detection is provided, by way of the leakage detection system with continuous monitoring, for the RHR [ Residual Heat Removal),
RCIC [ Reactor Core Isolation Cooling], MS [ Main Steam), RWCU
[ Reactor Water Cleanup], RECIRC [ Recirculation] and FW [Feedwater]
systems.
7.
The failure of any one of these pressure retaining piping welds would have no adverse effect or reduction in the margin of plant safety since there is isolation capability and/or shutdown capability as part of the plant design. The design analysis bounds the limiting fault conditions for line breaks in and outside of containment.
8.
The calculated maximum piping stresses and usage factor at the integral attachments on the piping, including consideration of the local pipe wall stresses, have been determined in the Class 1 Stress Report and are equal to the following:
a)
Primary plus secondary (equation 10); 32,775 psi (1.72 S,),
b)
[U] sage factor is 0.0442.
Circumferential and longitudinal welds in piping with stress levels below 2.4 S, and usage factors below 0.4 are excluded from ISI examinations, in accordance with Table IWB-2500-1 Category B-J.
9.
Examination at GGNS of Category B-J, B-K-1 and C-F welds have not identified any flaws or evidence of service induced degradation."
Alternative Testino - The licensee had previously committed to inspect all welds identified in Table 1 twice by volumetric or surface area examination during the 10-year interval. The licensee proposes to amend this commitment 1
to allow only the applicable parts of the subject welds identified in Table I to be inspected once during the inspection interval to the maximum extent practical as determined by the extent of the specific limitation.
Inspecting the welds once per inspection interval satisfiesSection XI of the ASME Code as stated in the code requirement section of this SE.
Each weld will be subjected to a volumetric or surface examination as required by Tables IWB and IWC 2500-1 of Section XI of the ASME Code.
From Table 1, the surface area of the welds will be examined 100%. The area for volumetric examination ranges from 30% to 80.8% of the weld.
Summary - The staff has reviewed the submittal which supports the licensee's conclusion that the Section XI ASME Code requirements are impractical for the piping welds identified in Table I due to the physical inaccessibility of portions of the welds. Compliance to the Code requirements would require the redesign and refabrication of the piping systems to eliminate physical obstructions due to pipe supports, pipe fittings, and components.
The proposed alternative limited volumetric examinations, along with the Section XI ASME Code surface examination and the hydrostatic tests, ensure an
S 7 "
i l
acceptable level of inservice structural integrity. The staff concludes that' i
relief should.be granted as requested in Relief Relief No. I-00010, Revision 5, due to physical inaccessibility of portions of the identified welds.
j
3.0 CONCLUSION
By letter dated February 18, 1993, the licensee has determined'that certain requirements for ISI in the ASME Code,Section XI, are impractical due to-i physical inaccessibiliity and has requested relief..We conclude from our
'i evaluation of the licensee's submittal that these examination requirements are 1
impractical to perform at the Grand Gulf Nuclear. Station, Unit 1. _ We. conclude that, for the components for which relief was requested, the proposed alternative examinations identified'in this SE give reasonable _ assurance of '
i the piping and component pressure boundary and component support structural i
integrity. We further conclude that revising the alternative testing methods to allow welds to be surface and volumetrically examined to the maximum extent practical as delineated in Table 1 of the Inservice _ Inspection Requirements -is l
acceptable.
Pursuant to 10 CFR 50.55a(g)(6)(i), the staff.has determined that t
the granting of the. relief requested is authorized by law, will not endanger life or property or the common defense and security, and is otherwise in'the i
public interest. The staff has given due consideration to the burden upon the
~
licensee that could result if the requirements were imposed on the facility.
Accordingly,-relief is granted for ISI Relief Request I-00010, Revision 5.
The relief granted is conditioned on the proposed alternative examinations.
j Principal Contributor:
V. G. Gaddy Dated: May 25, 1993 l
1
-l l
t I
l
'I t
-i r
l
_