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N UC LE AR. R EGU L ATO,RY COMMISSION.
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'VAsHINGTON D. C. 2o555
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JUL 0 419M
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g% j MEMQRANDUM FOR:
Gus C. Lairis, Assistant Di' rector Division of BWR Licensing THRU:
B. D. Liaw,i.hief Engineering B,anch Division of BWR Licensing FROM:
Robert A. 'iermann, Acting Section Leader Engineering Branch Division of BWR Licensint
SUBJECT:
UPDATE - RHR PUMP WEAR RING FAILURES The staf f has cor'itacted 'the remainirig 'two BWR's Coope'r and Vermont Yankee U determine their actions for RHR pump ins ections.
By letter dated July 11, 1986, Vermont Yankee (VY) informed the NRC they intended to inspect their pumps during operation beginning in December 1986.
Their inspection schedule is predictated on the lead time (ssociated with obtaining suitable replacement arts fer a long term solution to the pro *>lem should cracking be discovered in the wear rirgs.
VY has developed a comprehensive monitoring program consisting of sound vibration measurements / evaluation, pump power, anti bearing and winding temperature trending to be performed during monthly rump testing.
The licensee of Cooper has informed us through the project manager that they intend to inspect the RHR pumps during their refueling outage scheduled to start October. Pilgrim currontly is inspecting their RHR pumps during the outa,,e they are currently in.
The staff has contacted the pump vendor, to verify 611 facilities with pumps of *his design have been identified.
The vendor stated the utilities identified in Information Notice 86-39 are the effected BWRs.
The vendor stated in our telecor their records indicated that 4 of the model 16x20x25 CVIC pumps are possibly at Nine Mile Point Unit 1.
Niagara Mohawk was contacted and stated their safety related pumps at Unit I were not manufactured by Bingham Willamette.
The vendor pointed that wrought 420 martensitic stainless steel wear rings are utilized in other punps used in PWR auxiliary feedwater systems.
The vendor stated the wear rings are hard2ned to a range of 450 tt 525 Brinell.
In order to datermine if any further action was necessary with regard to PWR's with wrought hardened wear rings, we have performed a limited evaluation of the differences in operating condition for wear rings in RHR pumps in BWR's and auxiliary feed pumps in BVR's and the effects of those conditions in causing degradation of the wear rings by IGSCC.
We feel there are two major differences between 'he BWR and PWR applications that effect the susceptibility of the wear rings to 1GSCC.
They are the follcwing:
1)
BWR RHR pumps in shutdown cooling mode operate at a temperature of about 4200F (100 PSI steam) where maximum operating temperatures for PWR auxilia.y feedwater pumps are about 120 F.
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.The pH in BWR primary water during operation is slightly acidic (approx.
max 5.6) where the pH of PWR secondary water is slightly alkaline in (approx. 8.to 9).
Considering the differences stated above, we believe that a sucolement to the Information Notice 86-39 is not currently justified.
Conclusion 1)
All effected BWPs that have not performed inspections at ineir TA u,o have committed to a scheduled inspection of their RHR putos in an acceptable time frame.
2)
Although some PWR's may have hardened martensitic stainless steel that could be susceptible to IGSCC, we believe the differences in the operati.1g tumperature and water chemistry of the auxiliary feedW3ter system reduce the likelihood of degradatior, of the wear rings by IG$CC.
Therefore, no action is currently justified in supplementing the previous ir:ormation notice.
I lSl Robert A. Hermann, Section Leader Engineering Branch Division of BWR Licensing cc:
W. Houston G. Lainas B. D. Liaw W. Hazelton R. LaGrangc W. Koc H.
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V. Rooney W.
Long R. M. Young M. Virgilio DISTRIBUTION:
Occket Files BWEB/ Reading Files BWE6/Plut Files 0FC :BWF8
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NAME :R.HarQi:cd: 8. D. Gi aw h.........................................................:........................
DATE :7/?//86
- 7/ w/8ti 0FFICIAL RECORD COPY
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