ML17333A743
| ML17333A743 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 01/16/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17333A742 | List: |
| References | |
| NUDOCS 9701210458 | |
| Download: ML17333A743 (5) | |
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UN)TED STATES NUCLEAR REGULATORY COMMISSION WASHlNGTON, D.C. 8%55-0001 Y EVA UA ION Y T OFF C
OF NUC AR R ACTOR REGULATION E THIRD T N Y A NT RVA INSER IC NSP C
ON PLA R
ND 5250 a
2 OF ASME CODE SECTION XI NDIANA MICHIGAN POM R
C PANY DONALD C.
COOK NUCLEAR PLANT UNITS 1
AND 2 CKET NUMBERS: 50-315 AND 50-316 1.
INTRODUCTION The Technical Specifications for Donald C.
Cook Nuclear Station, Units 1 and 2, state that the inservice inspection and testing of the American Society of Mechanical Engineers (ASME) Code Class 1,
2 and 3 components shall be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel 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).
10 CFR 50.55a(a)(3) states that alternatives to the requirements of paragraph (g) may be used, when authorized by the NRC, if (i) the proposed alternatives would provide an acceptable level of quality and safety, or (ii) compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.
Pursuant to 10 CFR 50.55a(g)(4),
ASME Code Class 1,
2 and 3 components (including supports) shall meet the requirements, except the design and access provisions and the preservice examination requirements, set forth in the ASME Code,Section XI, "Rules for Inservice Inspection of Nuclear Power Plant Components,"
to the extent practical within the limitations of design, geometry and materials of construction of the components.
The regulations require that inservice examination of components and system pressure tests conducted during the first ten-year interval and subsequent intervals comply with the requirements in the latest edition and addenda of Section XI of the ASME Code incorporated by reference in 10 CFR 50.55a(b) on the date twelve months prior to the start of the 120-month interval, subject to the limitations and modifications listed therein.
The applicable edition of the ASME Code,Section XI, for D.C.
Cook Nuclear Plant Units 1 and 2, during the third ten-year inservice inspection (ISI) interval, is the 1989 Edition.
The components (including supports) may meet the requirements set forth in subsequent editions and addenda of the ASME Code incorporated by reference in 10 CFR 50.55a(b) subject to the limitations and modifications listed therein and subject to Commission approval.
Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASME Code is 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 9701210458 970116 PDR ADOCK 05000315 C
Code requirement.
After evaluation of the determination, pursuant to 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 endanger life, property, or the common defense and security, and are otherwise in the public interest, giving due consideration to the burden upon the licensee that could result if the requirements were imposed.
By letters dated October 25, 1996 (AEP:NRC:0969AY) and November 27,
- 1996, (AEP:NRC:0969AZ, Attachments 2 and 3) Indiana Hichigan Power
- Company, the licerisee for the D.C.
Cook Nuclear Plant Units 1 and 2, requested relief from the requirements of the 1989 Edition of the ASHE Boiler and Pressure Vessel Code,Section XI, in regard to VT-2 visual examination of insulated components stated in paragraph IWA-5242(a) and corrective measures if leakage occurs at bolted connections during system pressure tests, stated in Subsection IWA-5250(a)(2).
The staff has reviewed and evaluated the licensee's request and the supporting information on the relief request for the D.C.
Cook Units 1 and 2, pursuant to the provis'ions of 10 CFR 50.55a(a)(3)(i).
2.0 DISCUSSION
System/Component for which relief is requested All class 1,
2 and 3 systems borated for the purpose of reactivity control and components using bolted connection.
1989 ASNE Code,Section XI Requirements Subsection IWA-5242(a) requires that for systems borated for the purpose of controlling reactivity, insulation shall be removed from pressure retaining bolted connections for visual examination VT-2.
For other components, visual examination VT-2 may be conducted without the removal of insulation by examining the accessible and exposed surfaces and joints of the insulation.
Subsection IWA-5250 (a)(2) states that the source(s) of leakage detected during the conduct of a system pressure test shall be located and evaluated by the Owner for corrective action.
For leakage occur ring at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IWA-3100.
Basis for Code Relief:
(As stated in Attachments 2 and 3 to AEP:NRC:0969AZ)
"The implementation of code requirements as written and interpreted in the 1989 Edition of the ASIDE Section XI code for system pressure testing of class 1,
2 and 3 systems and components would be hazardous to Cook Nuclear Plant personnel.
Surface temperatures of some components to be VT-2 inspected at operating temperatures and pressures would be in excess of safe contact temperatures.
The removal and reinstallation of insulation and scaffolding for the purpose of performing a VT-2 inspection at operating conditions are not consistent with good ALARA practices.
This position is further supported by the following:
I 1.
Code Case N-533 issued by the ASHE Section XI organization which provides an acceptable alternative to the code method for class I systems.
2.
Code relief to use the requirements specified in Code Case N-533 has been granted to the V. C.
Summer and Surry Power Plants."
"The implementation of 1989 Edition code requirements for bolted connections requires that all bolts be removed for a VT-3 inspection if, through an evaluation, leakage is suspected.
The method stated in paragraph IWA-5250(a)(2) of the 1989 Edition of the ASHE Section XI code for the evaluation of bolted connections is not the most prudent method compared to the proposed alternative and may cause undue hardship, increase the danger to plant personnel, and result in significant outage time loss without a commensurate increase in safety and quality.
Removal of any or all bolting in bolted connections where leakage has been
- observed, in some cases, is not the most prudent action to take since leakage is generally not caused by degraded bolting which is the intent of the ASHE Section XI code.
Relief has been granted to Surry to use the alternative presented here."
Proposed Alternative:
(As stated in Attachments 2 and 3 to AEP:NRC:0969AZ)
"As an alternative to the requirements of the 1989 Edition of the ASHE Section XI Code, it is proposed for class I systems that the insulation be removed on bolted connections for systems, borated for the purpose of reactivity control, VT-2 examined, and evaluated for evidence of leakage during refueling activities at conditions that may be less than system operating conditions.
Additionally, a VT-2 inspection at system operating conditions after a four hour hold time will be performed with the insulation in place prior to returning the unit to service.
Similarly for class 2 and 3 systems, borated for the purpose of reactivity control, with the insulation removed at conditions which may be less than system operating conditions, a VT-2 examination and evaluation for evidence of leakage will be performed on bolted connections, followed by a VT-2 inspection after a four hold time with insulation in place at system operating conditions prior to returning the unit to service."
"As an alternative to the requirements of the 1989 Edition of the ASHE Section XI Code, it is proposed that if leakage is suspected or discovered at a bolted connection by a VT-2 examination during a system pressure test, either the bolt closest to the source of leakage will be removed, and a VT-3 examination will be conducted and evaluated in accordance with IWA-3100(a) or an engineering evaluation shall be conducted that will consider the following:
location of leakage; history of leakage; bolting material; evidence of corrosion with the connection assembled; corrosiveness of internal fluid; available information for similar bolting materials in similar environments;
and condition of other components in the vicinity that could also be degraded due to leakage.
Mhen the evaluation of the above criteria concludes that the leaking condition has not degraded the bolt, no further action is necessary. If the evaluation concludes bolting is degraded or is non-conclusive in determining degradation of bolting, the bolt closest to the source shall be removed, VT-3 examined and evaluated in accordance with IMA-3100 (a).
Mhen the removed bolt shows evidence of respectable degradation, all remaining bolting shall be removed and VT-3 examined and evaluated in accordance with IMA-3100 (a)."
3.0 V
U T 0 AND CO CLUSION:
In Attachment 1 to letter AEP:NRC:0969AY, the licensee has requested relief from the requirement of Subsection IWA-5242(a) of the 1989 Edition of the ASHE Code,Section XI which requires removal of all insulation from pressure-retaining bolted connections when a VT-2 visual examination during system pressure test is performed in systems borated for the purpose of reactivity control.
The licensee has proposed to use Code Case N-533 which requires (1) performance of the Code-required pressure test without removing the insulation, (2) examination of Class 1 bolted connections, each refueling
- outage, at atmospheric or static pressure with the insulation removed and (3) evaluation of any evidence of leakage in accordance with IWA-5250 of the ASIDE Code,Section XI.
Subsection IMA-5242(a) provides requirements for detecting leakage or evidence of leakage at bolted connections.
Performing a VT-2 visual examination during a system pressure test (system leakage test) as required by Code Case N-533, with the insulation in place will likely result in the detection of any significant leakage when a four-hour hold time is maintained after pressurization prior to the VT-2 visual examination.
Furthermore, performing a VT-2 visual examination after removal of the insulation at atmospheric or static pressure during outages, as specified by Code Case N-533, will detect evidence of borated water'eakage.
Any evidence of leakage, however, will be evaluated in accordance with IWA-5250 of the ASME Code,Section XI.
The staff, therefore, believes that the licensee's alternative provisions for test along with a four-hour hold prior to VT-2 visual examination during system leakage test, will detect any evidence of leakage, in a manner comparable to the requirements of the Code and thus it provides an acceptable level of quality and safety.
In Attachment 2 to letter AEP:NRC:0969AZ, the licensee has requested relief from the requirement of Subsection IWA-5250(a)(2) of the ASNE Code,Section XI, 1989 Edition which states that if leakage occurs at a bolted connection during system pressure test, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance with IMA-3100(a).
The
- licensee, however, has proposed to perform an evaluation of the bolted connection to determine the susceptibility of the bolting to corrosion and the potential for failure. If the evaluation concludes that bolting is degraded or is non-conclusive in determining degradation of bolting, the bolt closest
to the source shall be removed, VT-3 examined and evaluated in accordance with IWA-3100(a).
When the removed bolt shows evidence of rejectable degradation, all remaining bolting shall be removed and VT-3 examined and evaluated in accordance with IMA-3100(a).
This alternative allows the licensee to utilize a systematic approach and sound engineering judgement, provided that as a
minimum, all of the seven evaluation factors listed in the licensee's proposed alternative are considered.
As a result, the licensee's alternative to the Code required removal of bolting at a joint when leakage occurs will provide an acceptable level of quality and safety, as the integrity of the joint will be maintained.
Therefore, the staff concludes that the licensee's proposed alternative should be authorized pursuant to 10 CFR 50.55a(a)(3)(i).
The licensee is authorized to use Code Case N-533 until such time as the code case is included in a future revision of Regulatory Guide 1. 147.
At that time the licensee is to follow all provisions in Code Case N-533, with limitations issued in Regulatory Guide 1.147, if any, if the licensee continues to implement this relief request.
Principal Contributor:
P. Patnaik Dated:
january i6, i997