ML20070E179
| ML20070E179 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 07/08/1994 |
| From: | J. J. Barton GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| C321-94-2096, NUDOCS 9407140157 | |
| Download: ML20070E179 (12) | |
Text
,
GPU Nuclear Corporation Nuclear 88 Forked River. New Jersey 08731-0388 609 971-4000 Wnter's Direct Dial Number:
C321-94-2096 July 8,1994 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
Dear Sir:
Subject:
Oyster Creek Nuclear Generating Station Docket No. 50-219 Inservice Inspection Program Proposed Alternate Examinations / Request for Relief By letter dated April 16,1992, GPU Nuclear submitted the Inservice Inspection Program for the Third Ten Year Interval at the Oyster Creek Nuclear Generating j
Station. In accordance with 10 CFR 50.55a(b)(2) and 10 CFR 50.55a(g)(ii), this program was submitted to implement the requirements of ASME Section XI,1986 edition, with no addenda, j
By this letter, pursuant to 10 CFR 50.55a(a)(3), alternative testing requirements for the pressure testing portion of the referenced ASME code are being requested.
Enclosure I contains three (PT-R2, PT-R3, and PT-R4) requests for the use of j
specified alternate testing. Additionally, Enclosure 2 contains a revision to a previously submitted relief request. Request R12, which dealt with visual testing requirements, has been modified to specifically define a course of action to be taken in the event of a leaking bolted connection found during a system pressure test. A logic diagram, displayed in flow chart format, has been included to assist in the review of this request.
To support the upcoming 15R refueling outage, approval of these proposals is requested by September 1,1994.
/
940714o157 940708 A
PDR ADOCK 05000219
$T O
PDR GPU Nuclear Corporation is a subsdiary of General Pubac Utd. ties Corporahon i
l C321-94-2096 i
Page 2 r
If any additional information or assistance is required, please contact Mr. John Rogers of my staff at 609.971.4893.
n n
/
=
(.
J >hn J. E a n
ice Presi ent and Director Oyster Creek f
JJB/JJR Enclosures cc:
Oyster Creek NRC Project Manager l
Administrator, Region I Senior Resident Inspector i
- l 1
8 1
y e-+
e
j s
I t
i Pressure Test
[
Alternative Examinations 6
I J
P
PT-R2 j
PRESSURE TESTING REQUIRE 51ENTS FOR CLASS 1,
2, AND 3
]
COAfPONENTS FOLLOWING REPAIRS OR REPLACEAIENTS I
The following describes an alternative to the hydrostatic testing requirements of IWA-4000 and IWA-5000, for Class 1, 2. and 3 components following repairs or replacements.
t Requirement:
In accordance with IWA-4000 and IWA-5000, a hydrostatic pressure test shall be performed following repair or replacement of Class 1, 2, or 3 components by welding on the pressure retaining boundary.
Itasis:
The performance of a hydrostatic test of pressun: retaining components at elevated pressures, places a requirement on the utilities with little benefit.
l It has been shown that a hydrostatic test at elevated pressure only i
increases the leakage rate from that of a test run at nominal or nonnal operating pressures. Review of industry data, material, and construction i
requirements suppods this position.
I There have been numerous publications and ASME documentation regarding the lack of value of a hydrostatic pressure test at elevated pressure. This has led to the issuance of Code Case N-498, which eliminates the requirement to perfonn a hydrostatic test at elevated pressure for Class 1 and 2 systems as part of the periodic test mquimment.
This Code Case, which has been endorsed by Regulatory Guide 1.147, did not initially address Class 3 because pmssure tests served as the only form of i
examination (except for integral attachments) for Class 3 systems.
Equally lacking in value is the requirement to perform a hydrostatic pressure test at elevated pressures subsequent to repairs i
by welding and the attachment of replacements by welding. The ash 1E Committee has recognized this and consequently developed Code Case N-416-1 to provide an alternative. This Code Case has been approved by the AShfE Committee during the first quaner of 1994 and will be issued by ash 1E in Supplement 8 to ash!E
-l Section XI. GPUN feels that the requirements of this Code Case, as outlined below, provides a technically sound alternative to the current requirements.
I 4
4 Alternative: Testing and examination will be perfonned in accordance with ASME i
Code Case N-416-1, approved on February 15,1994, as delineated below:
For welded repairs and installation of replacement items by i
welding, a system leakage test may be used pmvided:
I a)
NDE is perfonned in accordance with the methods and acceptance criteria of the applicable Subsection of the 1992 Edition of Section III b)
Prior to or immediately upon return to service, a VT-2
]
visual examination shall be performed in conjunction with a system leakage test, using the 1992 Edition of Section I
XJ, in accordance with IWA-5000, at nominal operating pressure and temperature.
c)
Use of this Code Case shall be documented on an NIS-2 fann.
1
1 PT-R3 CLASS 3 ELEVATED HYDROSTATIC PRESSURE TESTING REQUIREMENTS The following is an alternative to performing the interval hydrostatic test at elevated pressure for Class 3 systems and components.
Requirement:
In accordance with Table IWD-2500-1, Categories D-A, D-B, and D-C, a system hydrostatic test is required to be perfonned once per inspection interval.
In accordance with IWD-5000, the hydrostatic test is required to be perfomied at either 110% or 125 % of relief valve setting, or design pressure.
Itasis:
The system hydrostatic test was originally designed to allow inspection for evidence of any leakage that might originate from through-wall cracks of the pressure boundary and to enhance the possibility of timely discovery of small through-wall flaws which, because of leak size, might not be readily detected by the installation of leak detection systems.
The inservice system hydrostatic pressure test required by ASME Section XI Code reflects the acceptance of the pressure test as, primarily, a means to enhance leakage detection during the examination of components under pressure rather than solely as a measure to detennine the structural integrity of the components. A poll of utilities by ASME revealed that the detection of leakage was not observed more frequently at hydrostatic test pressure than at opemting pressure.
The perfonnance of the interval hydrostatic pressure test of Class 3 components at elevated pressures places a requirement on the utilities with little benefit. It has been shown that a hydrostatic test at elevated pressure only increases the leakage mte from that of a leakage test mn at normal operating pressure. Review of industry data, material and construction requirements concerning Class 3 systems supports this position. Currently, for Class 1 and 2 systems, perfonning the hydrostatic test at nominal or nonnal operating pressure, as applicable, is acceptable in lieu of the hydrostatic pressure test at elevated pressure, via Code Case N-498 which has been endorsed by Regulatory Guide 1.147. Recognizing this concern, the ASME Committee has developed Code Case N-498-1 to extend these altemative rules to Class 3 components.
Code Case N-498-1 was approved by the ASME Committee, during the first quader of 1994 and will be issued in Supplement j
9 to ASME Section XI. GPUN feels that the requirements of this j
Code Case, as outlined below for Class 3 components, provides a technically sound altemative to the current requirements.
l Alternative: A system pressure test shall be conducted at or near the end of each i
inspection interval or during the same inspection period of each inspection interval ofInspection Program B.
The boundary subject to test pressurization during the system pressure test shall extend to all Class 3 components included in those portions of systems required to operate or support the safety system function up to and including the first nonnally closed valve (including a safety or relief valve) or valve capable of automatic closure when the safety function is required.
The systems shall be pressurized to nonnal operating pressure for at least 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for insulated systems and 10 minutes for non-insulated systems.
The system shall be maintained at nonnal operating pressure during the perfonnance of the VT-2 visual examination.
i The VT-2 visual examination shall include all components within the boundary identified in item (2) above.
i Test instrumentation requirements (IWA-5260) are not applicable.
i
l 4
FT-R4 l
PRESSURF RETAINING PIPING AT CONTAINMENT PENETRATIONS The following is an alternative to perfonning the Section XI periodic pressure testing on those Class 2 portions of piping at containment penetrations whem the balance of the adjoining system is classified as Non-Class.
Requirement:
In accordance with Table IWC-2500-1, Category C-H, periodic system pressure testing is required to be performed on all Class 2 piping.
Basis:
The safety function of these lines is to become part of the containment isolation system during periods when containment isolation is requimd.
Therefore the pressure testing requirements should be based on the containment system design, not the associated process system design requirements.
These lines are tested in accordance with 10CFR50 Appendix J, Reactor Containment Ixakage Testing for Water Cooled Power Reactors, commensurate with the safety function the line performs, I
and in accordance with Technical Specification surveillance requirements.
Recognizing this situation, the ASME Committee is developing Code Case N-522, which allows the leakage testing requirements of 10CFR50 Appendix J to satisfy the periodic pressure testing requirements of ASME Section XI, Subsection IWC, on these isolated portions of Class 2 piping which are classified only for the purpose of containment integrity.
i l.
Alternative: The 10CFR50 Appendix J testing will satisfy the periodic pressure testing i
requirements of ASME Section XI, Subsectica IWC, per the allemative i
requirements of pending Code Case N-522.
l l
l
Revised Request for Relief; Visual Examinations of Leaking Bolted Flanges
RI2 REV1 i
i R1310 VAL OF IlOLTING ON CLASS 1 (EXCEPT CRD IIOUSING CONNECTIONS),2, AND 3 PRESSURE-RETAINING IlOLTED CONNECTIONS i
WIIEN LEAKAGE IS DETECTED l
The following describes an alternative to the automatic removal of all bolting at pressure-retaining bolted connections, when evidence of leakage is located dring system pressure testing (reference paragraph 6.2.4).
Requirement:
ASME Section XI 1986 Edition, Paragmph IWA-5250(a)(2),..."if leakage occurs at a bolted connection, the bolting shall be 3
removed, VT-3 examined for corrosion, and evaluated in accordance with IWA-3100;"..
Ilasis:
Regulatory Authorities have already determined that a more relaxed approach regarding bolting removal at leaking connections provides an i
acceptable alternative to the current requirements. This is evident by the rules pmvided in later editions of the Code (i.e.,1992 Edition with 1993 Addenda). This later requirement states that "Ifleakage occurs at a bolted connection on other than a gaseous system, one of the bolts shall be removed, VT-3 examined, and evaluated in accordance with IWA-3100.
1 The bolt selected shall be the one closest to the source of the leakage.
When the removed bolt has evidence of degradation, all remaining bolting in the connection shall be removed, VT-3 examined, and evaluated'in accordance with IWA-3100."
GPUN feels that the later Code requirements are a better approach j
to imiting removal at leaking connections, however, GPUN also i
feels that some other considerations should be addressed, as follows:
I (a)
If the bolted connection is leaking during system start-up and it is documented that the leakage stops at normal operating temperature, no further action shall be mquired, since the leakage is not continuous and therefore, would not result in degradation of the i
- bolting, j
l (b)
If the bolting in the connection was examined or replaced during-the curmnt outage, no further action shall be required.
(c)
If bolt removal becomes necessary, a VT-1 examination should be performed in lieu of the required VT-3 examination since this method is consistent with Section XI bolting examination requirements, and is better suitable for evaluation of corrosion.
(d)
Over the past ten years preventive and/or corrective maintenance activities were performed on approximately 80 ISI valves. The valve maintenance histories have shown that where leakage has occurred and the bolts were located in the path of the leakage flow stream, no corrosion was found in the threaded areas. Based on these observations, GPUN believes the immediate removal of a single bolt because of leakage is not warranted. If the exposed surface of the bolt / stud, nuts, or flange exhibits any evidence of degredation, the bolt should be removed for examination immediately. If no evidence of coration exists, the removal of a bolt at the next system out of serv ce window or scheduled refueling outage is sufficient to assure continued serviceability.
Alternative: If leakage occurs at a bolted connection on other than a gaseous system, and continues to leak once operating temperature has been obtained and the bolted connection was not replaced or examined during the current outage, an in-place VT-1 examination shall immediately be performed on the entire bolted connection. If evidence of corrosion is detected on any part of the bolted connection or flange surface, then the bolt closest to the source of the leakage shall be removed, V_T_1 examined, and evaluated in accordance with IWA-3100. When the removed bolt has evidence of degradation, all remaining bolting in the connection shall be removed, VT-1 examined, and evaluated in accordance with IWA-3100.
If no evidence of corrosion exists on any part of the bolted connection or flange surface, the removal of the bolt closest to the source of leakage shall be deferred to the next system out of service or scheduled refueling outage. The removed bolt shall be VT-1 examined, and evaluated in accordance with IWA-3100.
When the removed bolt has evidence of deFradation, all remaining bolting in the connection shall be removed, VT-1 examined, and evaluated in accordance with IWA-3100.
The flow chart on the next page depicts the logic above.
WA-5250(ah'2) CO9lECTIVE AC" O \\
CYN
^
FCT Of UF NC E
c5EI SNIEM PMEISSURE TEST.
PERFORM VT-1 EX AM IN ATIO N S IN-P L ACE.
/
\\ NO FIND g/
YES EVIDENCE p_
N CORROSION/
b r'
NENT AT N EXT i sT o t y SCHEDULED SYSTEM OUT OF sE nvicE RECORD OF BOLT
\\
INSPECTION
/
REMOVE BOLT CLOSEST TO THE LEAK AND EVALUATE PER IW A-3100.
1 r
\\\\
REMOVED BOLT IS k-r=y[77 gem
/
gg B O LTI N G YES CORRODED NO
.