ML19340B353
| ML19340B353 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/01/1980 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-80-13, NUDOCS 8010220131 | |
| Download: ML19340B353 (2) | |
Text
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1 Consumers POVlcr Company General off6ces 212 West Michigen Avenue Jockeon, M6chleen 49201 * (517) 788 4650 October 1, 1980 Mr James G Keppler Office of Inspection and Enforcement Region III US Huclear Regulatory Co= mission 799 Roosevelt Road Glen Ellyn, IL 60137 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - RESPONSE TO IE BULLETIN NO 80 CRACKING IN CORE SPRAY SPARGERS IE Bulletin No 80-13, dated May 12, 1980, entitled " Cracking in Core Spray Spargers" requires licensees to perform visual inspections of the core spray spargers at all upcoming refueling outages until further notice. This require-ment was based on the cracking observed at Oyster Creek and Pilgrim Nuclear Power Stations. The cracking observed was postulated to be initiated and pro-pagated by intergranular stress corrosion (IGSCC).
During the last refueling outage at Big Rock Point, Consumers Power Company re-placed the core spray sparger to enhance the spray pattern. Materials and fab-rication methods were specifically chosen to reduce its susceptability to IGSCC.
Type 316 Austenitic Stainless Steel (carbon content 0.02% max) was used for the sparger base material. The material was supplied in the solution heat-treated condition which further reduces the material's susceptability to IGSCC. The velding techniques employed are not considered to be factors for IGSCC initiation, because interpass temperatures were limited to 350 F and 308L filler metal used has a high resistant to IGSCC. Therefore, sensitization and susceptability of the new spaiger to IGSCC is considered to be very lov.
On September 10 and 11, 1980 a remote visual inspection capable of resolving a
.001 inch strand of wire on a neutral gray card by in-situ viewing was performed on the replaced sparger in Big Rock Point's spent fuel pool. The examination did not reveal any indication of cracking in the replaced sparger (30hSS base metal).
The examination coverage was limited to less than 100% by obstructions in the spent fuel pool, although the coverage closely approximated that which would be obtained in inspecting the new sparger in-place because of its proximity to the reactor vessel vall and internal steam baffles. The replaced sparger had been inservice for a period in excess of 17 years indicating that the environment and stresses to which it was subjected were insufficient to initiate IGSCC.
OCT 8010220 l 31
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fl' C:nsum;rs Power Company
' R2:;ponsa to IE Bu11stin 80-13 2
Cracking in Core Spray Spargsrs
-October 1, 1980 i*
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Based on the low susceptability of the new sparger to IGSCC and the results of l
the inspection of the replaced sparger which indicate a non-severe environment, Consumers Power Company does not intend to inspect the new sparger during all l
upcoming refueling outages. Instead, in the interest of ALARA and maintaining l
system integrity by inspection, Consumers Power Company vill follow ASME B&PV l
Code,Section XI requirements by inspecting the sparger every h0 months.
i 0 YWff Davi Hoffman Nuclear Licensing Administrator CC Director, Office of Nuclear Reactor Regulation Director, Office of Inspection and Enforcement NRC Resident Inspector - Big Rock Point l
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