ML20034A966
| ML20034A966 | |
| Person / Time | |
|---|---|
| Issue date: | 04/18/1990 |
| From: | Novak T NRC OFFICE FOR ANALYSIS & EVALUATION OF OPERATIONAL DATA (AEOD) |
| To: | Holahan G, Varga S Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20034A967 | List: |
| References | |
| AEOD-E90-04, AEOD-E90-4, NUDOCS 9004250151 | |
| Download: ML20034A966 (3) | |
Text
APR 1 g 1990 ME'MORANDUM:
Stevai A. Varga, Director Division of Reactor Project-I/II Office of Nuclear Reactor Regulations Gary M. Holahan, Acting Director Division of Reactor Project-III/IV/V & Special Projects Office of Nuclear Reactor Regulations i
FROM:
Thomas M. Novak, Director i
Division of Safety Programs Office for Analysis and Evaluation of Operational Data
SUBJECT:
SWELLING AND CRACKING IN HAFNIUM CONTROL RODS Enclosed is AE0D/E90-04 on the above subject. Hafnium was introduced 6s a neutron absorber for use in control rods in 1980.
It was meant to be used in 1
addition to carbon tetraboride (B4C) as a replacement for silver-indium-cadmium i
(Ag-In-Cd). Hafnium control rods were introduced as original equipment in
~
several later PWRs. They have experienced swelling and cracking as determined by several licensees using eddy current testing. Of the 14 plants licensed to use hafnium rods, six have replaced or will replace them, two never installed them, four have recently or may soon install them, and two are continuing to use them. Analyses by Westinghouse of the effects of swelling of control rods predict that neither physical interference with insertion nor mechanical resistance which would increase rod drop time will be of a large enough magnitude to invalidate FSAR safety analysis conclusions.
Eddy current test results to dau have upheld these analyses.
Given the limited examinations to date, it would be prudent to continue to require all plants licensed to use hafnium control rods to perform NDE of these rods to determine the extent if any of cracking, swelling, and wear.
Original signed by Thomas M. Novak, Director i
Division of Safety Programs l
Office for Analysis and Evaluation l
of Operational Data
Enclosure:
As stated cc w/ enclosure:
S. Sands, NRR M. Malloy, NRR G. Dick, NRR P. Shemanski, NRR D. Jaffe, NRR J. B. Hopkins, NRR T. Alexion, NRR R. Becker, NRR D. Pickett, NRR D. Queener, NOAC J. Wheelock, INP0 H. Faulkner, IP Distribution:
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TNovak MTaylor, EDO O,
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MWegr.er SRubin PBaranowsky, NRR J
b MChiramal GZech PW1111ams o
JRosenthal t
b See Previous Concurrences *
/
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ROAB:DSP:AEOD*
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3/26/90 3/26/90 3/ /90 une rulE90mmcon 4/
MEMORANDUM:
Steven A. Yarga, Director Division of Reactor Project-I/II Office of Nuclear Reactor Regulations Gary M. Holahan, Acting Director Division of Reactor Project-!!!/IV/V & Special Projects Office of Nuclear Reactor Regulations FROM:
Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluati of Operational Data
SUBJECT:
SWELLING AND CRACKING IN HAF UM CONTROL RODS Enclosed is AEOD/E90-04 on the above sub ct.
Hafnium was introduced as a neutron absorber for use in control rod in 1980.
It was meant to be used in addition to carbon tetraboride (B40) a a replacement for silver-indium-cadmium (Ag-In-Cd). Hafnium control rods wer introduced as original equipment in several later PWRs. They have expe enced swelling and cracking as determined by several licensees using eddy cu rent testing. Of the 14 piants licensed to use hafnium rods, six have repla d or will re) lace them, two never installed them, four have recently or may ocn install titm, and two are continuing to use them. Analyses of the eff cts of swelling of control rods predict that neither physical interference with insertion nor mechanical resistance which-would increase rod drop time will be of a large enough magnitude to invalidate FSAR safety analysis conclu ions. Eddy current test results to date have up-held these analyses.
Given the limited exami tions to date, it would be prudent to continue to require all plants lie nsed to use hafnium control rods to perform NDE of these rods to determine th extent if any of cracking, swelling, and wear.
Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data cc w/ enclosure:
S. Sanos, NRR M. Malloy, NRR G. Dick, NRR P. Shemanski, NRR D. Jaffe, NRR J. B. Hopkins, NRR T. Alexion, NRR R. Becker, NRR D. Pickett,.NRR Distribution:
PDR EJordan KBlack Central File Dross RSavio, ACRS ROAB R/F 1Novak MTaylor, EDO DSP R/F LSpessard KRaglin, TTC MWegner SRubin PBaranowsky, NRP, MChiramal GZech HFaulkner, IP JRosenthal MW1111ams JWheelock, INPO DQ ener, NOAC
- See Previous Concurrences ROAB:DSP:AEOD*
ROAB:DSP:AEOD*
C,0
- DSP:AE00 D:DSP:AEOD MWegner:mmk MChiramal JRo enthal TNovak 3/26/90 3/26/90 3
/90 3/ /90
MLMORANDUM:
Steven A. Yarga, Director Division of Reactor Project-1/II i
Office of Nuclear Reactor Pegulations i
Gary M. Holahan, Acting Director Division of Reactor Project-III/IV/V & Special Projects Office of Nuclear Reactor Regulations
/
FROM:
Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data
SUBJECT:
SWELLING AND CRACKING IN HAFN CONTROL RODS Enclosed is AEOD/E90-04 on the above su ct.
Hafnium was introduced as a neutron absorber for use in control r s-in 1980.
It was meant to be used in addition to carbon tetraboride (B4C as a replacement for silver-indium-caomium 1
(Ag-In-Cd). Hafnium control rods ere introduced as original equipment in several later PWRs. They have e erienced swelling and cracking as determined by several licensees using edd current testing.
Of the 14 plants licensed to use hafnium rods, six have re aced or will replace them, two never installed them, four have recently or ay soon install them, and two are continuing to use them. Analyses of the ffects of swelling of control rods postulate that neither physical interfer nce with insertion or mechanical resistance which would increase rod drop ime would be of a large encugh magnitude to invalidate FSAR safety analysis c clusions.
ECT findings to date have upheld these analyses. GiventheJmitedexaminationstodate,itwouldbeprudentto require all plants censed to use hafnium control rods to perform NDE of these rods to determine t extent if any of cracking, swelling, and wear as long as they are in use i he reactor.
Thomas M. Novak Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data cc w/ enclosure:
S. Sands, NRR M. Malloy, NRR G. Dick, NRR P. Shemanski, NRR D. Jaffe, NRR J. B. Hopkins. NRR T. Alexion, NRR R. Becker, NRR D. Pickett, NRR Distribution:
PDR Edordan KBlack Central File Dross RSavio, ACRS ROAB R/F TNovak MTaylor, ED0 r
DSP R/F LSpessard KRaglin, TTC MWegner SRubin PBaranowsky, NRR MChiramal GZech HFaulkner, IP JRosenthal MWilliams JWheelock, INPO DQueener,NOAC ROAB:DSP:AE0D ROAB:DSP:AEOD C:ROAB:DSP:AEOD D:DSP:AEOD MWegner:mmk MChiramal' JRosenthal TNovak 3/f4/
3/q/90 N 3/ /90 3/ /90
.