ML18038A970
| ML18038A970 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 10/17/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18038A967 | List: |
| References | |
| NUDOCS 9410250099 | |
| Download: ML18038A970 (5) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON. D.C. 20555.0001 S
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0 I. 0 JIIIBXUUR The Technical Specifications for Browns Ferry Nuclear Plant (BFN) Unit 2,;- - ',
state that the inservice inspection and testing of the American Society of Mechanical Engineers (ASHE) Code Class 1, 2, and 3 components shall be; performed in accordance with Section XI of the ASHE 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,-
As stated in 10 CFR 50.55a(a)(3),
al,ternatives 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 ASHE
- 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 10-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 12 months prior to the start of 'the 120-month interval, subject to the limitations and modifications listed therein.
The applicable edition of Section XI of the ASHE Code for the Browns Ferry Nuclear Plant Unit 2, second 10-year inservice inspection (ISI) interval, is the 1986 Edition.
Pursuant to 10 CFR 50.55a(g)(5), if the licensee determines that conformance with an examination requirement of Section XI of the ASHE 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 ASHE Code requirement.
After evaluation of the determination, pursuant to 4102500~+ 940 PDR ADOCK PDR P
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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 letter dated July 8, 1994, the licensee, Tennessee Valley Authority, submitted Request for Relief No.
SPT-7. proposing to use provisions of the 1992 Edition of the ASHE Boiler Vessel
- Code, IWA-5250(a)(2) as an alternative method of testing bolted connections.
2.0
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S ste ess Test Co ect v a
Bolted Connections o
eacto ecircul o
V lve 2-CV-68-33.
Code Re uireme tsSection XI, IWA-5250(a)(2) requires that if leakage occurs at a bolted connection, the bolting shall be removed, VT-3 visually examined for corrosion, and evaluated in accordance, with IWA-3100.
Licensee's Code Relief Re uest:
Relief is requested to substitute the reference paragraph IWA-5250(a)(2) from the 1992 Edition as an alternative in>
lieu of the wording in the 1986 Edition.
L ce s e's B s s
est n
e:
IWA-5250(a)(2),
1992 Edition, of the ASIDE Boiler and Pressure vessel Code, requires one bolt for reactor recirculation valve 2-FCV-68-33 to be removed and inspected for corrosion.
The bolt removed must be the one closest to the source of leakage.
- Whereas, ASNE Boiler and Pressure Vessel Code 1986 Edition requires removal and inspection of all 24 bolts.
IWA-5250(a)(2),
1992 Code Edition, recognizes that the bolts in the area of the process fluid leaking at a bolted connection are susceptible to corrosion due to the leak.
However, this code edition considers removal and inspection of one bolt closest to the leak as an adequate representation of the bolting that has been wetted by the leaking joint.
Reactor recirculation valve 2-FCV-68-33 cannot be isolated from the reactor vessel.
Should galling of the stud to valve body occur, it would be necessary to rethread the valve body.
Rethreading of the valve body would require removal of the valve bonnet.
Removal of the valve bonnet would require plugging of the jet pumps.
The performance of this work would require approximately two weeks.
The estimated radiation exposure of this work is approximately 15 man-rem.
This estimate is based on a crew of two men, a
galling rate of 50 percent, a stud removal rate of two hours per
- stud, and rethreading rate of 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> per stud, and a radiation field of 40 mrem per hour.
Since the.1992 Edition of the ASHE Boiler and Pressure Vessel Code recognizes removal and inspection of one bolt as an acceptable corrective action for a leaking mechanical joint, TVA considers that the proposed alternative provides a reasonable inspection to allow verification of valve 2-FCV-68-33 stud integrity without any reduction in the level of quality or safety.
e '
TVA will take corrective actions per IWA-5250(a)(2),
1992 Edition of the ASHE Boiler and Pressure Vessel Code.
IWA-5250(a)(2),
states: "If leakage occurs at a bolted connection, one of the bolts shall be removed, VT-3 examined, and evaluated in accordance.
with IWA-3100.
The bolt selected shall be the one closest to the source of 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. "
3.0 V
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CO C US The 1986 Edition requires that all bolting be removed and VT-3 examined at all leaking bolted connections.
The 1992 Edition requires removal of one of the bolts closest to the leakage.
When the removed bolt has evidence of degradation, all remaining bolting in the connection shall be removed, VT-3
- examined, and evaluated.
The 1992 Edition relies on the training and skill of the certified VT-3 inspector to detect degradation.
This concept provides an acceptable level of quality and safety in that the area exposed to leakage is evaluated.
Based on above, the licensee's proposed alternative to use paragraph IWA-5250(a)(2) from the 1992 Edition of ASME Section XI is authorized pursuant to 10 CFR 50.55a(a)(3)(i).
Principal Contributor:
T. McLellan Dated:
October, 17, 1994
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