ML19308E178
| ML19308E178 | |
| Person / Time | |
|---|---|
| Site: | Crystal River  |
| Issue date: | 12/05/1973 |
| From: | Deyoung R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Rodgers J FLORIDA POWER CORP. |
| References | |
| NUDOCS 8003240711 | |
| Download: ML19308E178 (2) | |
Text
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Docket No. 50-302 g
59 Florida Power Corporation ATTN: Mr. J. T. Rodgers Assistant Vice President and Buclear Project Maanger P. O. Box 14042 St. Petersburg, Florida 33733 Gentlemen:
Inspection of hydraulic shock suppressors (saubbers) in nuclear power plants has revealed that a large percentage of the seals in units supplied by the Bergen-Patterson Company were defective and that defects can recur in six weeks time or less. Two different seal materials have been used in Bergen-Patterson (R-P) snubbers; a =411mble gun polyurethane which contains plasticizers and other additives, and a molded polyurethana known to be free of these additives. Based on limited available information it is postu-lated that dissolving of the plasticiser into the silicone hydraulic fluid has caused seal shrinkage and deterioration. Therefore, =411mble gum polyurethane should not be used in hydraulic sunbbers, except on an emergency basis.
The performance and reliability of molded polyurethane free of additives in a reactor environment has not yet been established. Test data indicate that an incompatibility may also exist between molded polyurethana and the silicone fluid which may limit the inservice life of the molded material.
The use of molded polyurethans seals should, therefore, be considered only
-as an interim measure until more data is available or an improved material is established.
B-P is coordinating a development program to determine a long-term solution to the current snubber problem.
' Based on the above considerations, we are requiring that the following actions be taken. If Crystal River, Unit 3, has B-P anubbers installed on any safety related systems, you will be required to modify the seals on these snubbers with a material that has been demonstrated to be compatible with the hydraulic fluid in the operating environmast. If such a material is not available on a schedule compatible with your fuel loading date, the use of molded polyurethane seals known to be free of additives will be acceptable as an interim measure. However, you will be required to reinspect these interin seals whenever the reactor is shutdown for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or longer and these snubbers have not been inspected for 30 days, but in no event shall the interval between inspections exceed 120 days.
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Plorida Power Corporation Any defective units found during these inspections aball be re returning to power operation.
paired before use of millable gun seals, only defective units need be repairedIf u these conditions, you will be required to reinspect every 30 d Under earliest practical time. compatible seal material is installed, which shou ays until 4
During the required inspections of B-P snubbers, you will als to inspect all snubbers supplied by em = facturers other than B P o be required will also be required to report the results of all inspections and an
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. You repairs or corrective actions taken to the Directorate of Licensing
- Periodic surveillance of all snubbers installed on safety related sy will be required by the Technical specifications for Crystal River If interim seal materials are ased, the Technical Specificati, Unit 3.
reflect the inspection and reporting requirements as discussed above ons must seal materials of demonstrated cougatibility with the hydraulic fluid If operating environment are used, the Technical Specifications abauld r and inspection requirements that consider the potential degradation r t e ect the snubber seal material used and be consistent with a a e of snubbers will perform satisfactorily when needed.
ssuring that the You are hereby requested to inform us within 60 days of your making snubber seal modifications and to submit proposed Techni plans for Specifications for a curveillance program for the snubbers i cal Unit 3.
n Crystal River, Please contact us if you have any questions concerning thi s matter.
Sincerely.
Origtna) W by R. C. DeYoust R. C. DeYoung, Assistant Director for Pressurised Water Reactors Directorate of Licensing ces S. A. Brandimore Vice President & General Counsel DISTRIBUTION:
P. O. Box 14042 AEC PDR ASchwencer St. Petersburg, Florida 33733 T,odal PDR EGoulbourne M cket File BBuckle; RP Rdg File DSells PWR-4 Rdg File PWR BCs RCDeYoung ACRS (16)
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