IR 05000261/1991003
| ML14178A095 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 03/21/1991 |
| From: | Merriweather N, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML14178A094 | List: |
| References | |
| 50-261-91-03, 50-261-91-3, NUDOCS 9104110291 | |
| Download: ML14178A095 (8) | |
Text
ftt REGU 4UNITED STATES 0G NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA STREET, )1\\
aATLANTA, GEORGIA 30323 Report No.:
50-261/91-03 Licensee:
Carolina Power and Light Company P. 0. Box 1551 Raleigh, NC 27602 Docket No.:
50-261 License No.:
DPR-23 Facility Name: H. B. Robinson Inspection Conducted:
February 19-22, 1991 Inspector: 'pI, : l
"I,'~'
N. Merriweather Date Signed Approved by:
2 /91 M. Shymloc Chief
/Dtd Signed Plant Syst s Section Engineering Branch Division of Reactor Safety SUMMARY Scope:
This routine, announced inspection examined the licensee's corrective action programs for previous inspection items and nonroutine licensee event reports in the area of environmental qualification of electrical equipmen The items examined were NRC Violation 50-261/87-10-04 and Unresolved Items 50-261/89-26-01, -03, and 04; and Licensee Event Reports 88-15 and 89-1 Results:
In the areas inspected, violations or deviations were not identifie The licensee's corrective action programs were considered complete and adequate for all but one of the items examine The licensee was very cooperative and responded to NRC requests in a timely manne A new Unresolved Item (50-261/91-03-01)
was opened to consolidate into a single item a concern remaining from the followup on Violation 50-261/87-10-04 and Licensee Event Report 89-13. The concern relates to the adequacy of the documentation used to establish qualification for Patel Conduit Seals. These seals were installed to prevent moisture from entering electrical components under design bases accident conditions. Although the licensee had performed additional testing on the seals to support qualification, the test reports were ambiguous as to whether the seals actually met the test plan acceptance criteria of no leakage during LOCA and submergence testin This item is discussed further in paragraph PDR ADOCK 05000261 r)
REPORT DETAILS 1. Persons Contacted Licensee Employees
- S. Billings, Technical Aide, Regulatory Compliance
- R. Crook, Senior Specialist, Regulatory Compliance
- W. Dorman, Manager, Nuclear Assessment Department
- A. McCauley, Manager, Electrical Systems
- M. Page, Manaaer, Technical Support
- Sheppard, Plant General Manager
- D. Stadler, Onsite Licensing Engineer, Nuclear Licensing
- H. Young, Manager, Quality Control C. Harris-Young, Environmental Qualification Coordinator Other licensee employees contacted during this inspection included engineers, security force members, and administrative personne Other Organizations F. Roy, EGS Environmental Qualification Engineer NRC Resident Inspectors
- L. Garner, Senior Resident Inspector
- K. Jury, Resident Inspector
- Attended exit interview Acronyms and initialisms used throughout this report are listed in the last paragrap. Action on Previous Inspection Findings (92701) (92702) (Closed) Violation 50-261/87-10-04, Cable Entrance Seals for Solenoid Valves and Transmitters (Violation C in the NOV dated June 16, 1988)
The violation involved a failure to install conduit seals on ASCO solenoid valves and Rosemount 1153A transmitter The corrective action taken by the licensee was to install Patel Conduit Seals on those EQ instruments that required a moisture sea The corrective action was previously reviewed during NRC Inspection 50-261/89-2 The above inspection identified several concerns with the qualifica tion documentation for Patel Conduit Seal To resolve the concerns identified in Inspection Report 50-261/89-26 the licensee performed requalification testing on four seal configurations similar to those at Robinso The testing program was performed from June 4, 1990, through October 8, 199 The results are documented in Wyle
Laboratories Test Report No. 41175-1, Volumes I and II and EGS Corporation International Report No. EGS-TR-903200-0 The testing performed by Wyle Laboratories included a LOCA test followed by a 30 day submergence test. During the LOCA and submergence testing phases two of the four Robinson seals leaked (i.e. CS-1A and CS-2).
After the submergence test all test specimens were pressure tested through tubing on the low pressure side of the seal Specimens CS-1A and CS-2 leaked at the NPT pipe threads. The specimens were removed from the test chamber and provided to EGS for further evaluation of the test anomalie EGS tested the four Robinson seals for leakage through their wires and through the grommet EGS pressurized the seals with nitrogen and verified leakage at the NPT threaded connection on specimens CS-1A and CS-2 at 50 psi Specimens CS-1A and CS-2 were disassembled, resealed and then retested. No leakage was observed at a 75 psig test pressure. Specimens CS-3A and CS-4 leaked at the 75 psig test pressur The NPT joint was resealed on both CS-3A and CS-4. A retest of CS-3A showed leakage at 60 psi No leakage was observed on CS-EGS concluded that the leakage observed during the LOCA and submergence test was due to failure of the thread sealant at the NPT joint EGS concluded that both CS-3A and CS-4 were also prone to NPT leakag The licensee concluded that the anomalies observed during the testing did not affect the qualification of the seals at Robinson. This was based on the EGS test data and the fact that the seals at Robinson were assembled using a different thread sealant than the one used in the test. The sealant used at Robinson was Loctite PST-580 which was LOCA and submergence tested by Rosemoun The test specimens were assembled using a EGS P-2 thread sealan The inspector reviewed documentation from the licensee's files that was used to establish qualification for Loctit The inspector considered the information inconsistent and lacking as delineated below:
(1) The licensee's Maintenance Manual Procedure MMM-025 identified the sealant as nonage sensitive when in fact test reports in their files concluded the sealant was age sensitiv (2) The plant installation procedure (MMM-025) for applying the Loctite sealant on conduit threads required four to seven turns or a minimum of 150 in-lb torqu However, the Rosemount Instruction Manual indicated that Loctite was used between the electronics housing and sensor threaded connectio It specified five full threads of engagemen (3) The submergence test performed by Rosemount was a two week test and not the 30 day Robinson Profil Not withstanding the above, the inspector disagreed with the licensee that the post LOCA testing on the Patel Seals conclusively established that moisture leakage was due to the NPT threaded pipe connectio This was based on the fact that the post LOCA testing data for tubing, seal and NPT joint leakage showed that specimen CS-2 leaked nitrogen at 70 psig through the threaded NPT join However, during submergence testing the specimen leaked at maximum pressures of 6.4 psig. The EGS nitrogen leak testing of the seal and NPT joint showed leaks at 50 psig from the threaded join This did not provide an explanation for leakage at lower pressures while submerge In addition to the above, the Wyle test included four other Patel seals that were subjected to the LOCA and submergence testing phases. Three of the four specimens leaked (CS-5A, CS-10 and CS-12).
No leakage was observed post LOCA on either the tubing or the conduit seals for CS-10 and CS-12 at nitrogen pressures of 70 psi Specimen CS-5A leaked at a flange weld at 70 psi All of these specimens had observed leakage while submerged at pressures of eight psi There were also anomalies reported with two other specimens (CS-6 and 7A).
Specimen CS-6 leaked after seismic testing requiring it to be removed from the test program. The cause of the leakage on CS-7A was not determine The inspector concluded that the reports were inconclusive in establishing qualification for the seal The anomalies observed, whether thread or grommet leakage, were failures of the test acceptance criteria and the Post LOCA testing was insufficient to resolve those LOCA and submergence concern This issue is considered an Unresolved Item (50-261/91-03-01) pending further NRC evaluation of the test report The violation is considered close (Closed)
Unresolved Item 50-261/89-26-01, Victoreen High Range Radiation Monitor The installed configuration of the Victoreen High Range Radiation Monitor was not the same as the qualified tested configuration and the deviations had not been adequately addressed by the license The qualified tested configuration used a sealed metal conduit configuration to protect the electrical termination at the detector from moisture intrusio The installed configuration at Robinson used heat shrink material on stainless steel pipe to seal the cable entrance at the detector. The heat shrink materials were previously qualified for use on cable inside containment, however, adequate test data was not available to support qualification on stainless steel pipe. The licensee performed additional qualification testing on the Robinson configuratio The test specimen was assembled with heat shrink material on stainless steel pipe similar to the ones installed at Robinso The test was conducted at LOCA temperatures and
pressures that enveloped the accident profile at Robinson. The test and results are discussed in the same Wyle and EGS reports referenced in paragraph 2.a abov The seal passed the test with no anomalie This item is now close (Closed)
Unresolved Item 50-261/89-26-03, Review Qualification for Raychem Penetration Seal In LER 88-22 the licensee reported that the containment flood level was higher than what was initially analyze This resulted in several EQ components being subject to submergence that were not analyze The licensee performed an evaluation of the components that were submerged and concluded that they were acceptabl However, they made repairs on penetration "F01" to protect the penetration pigtail wires with Kapton insulation from interacting with chemical spray during a design basis even Repairs made to penetration
"F01" consisted of installing Raychem heat shrink material over the stainless steel feed through and the Kapton pigtail cables to seal the penetration from moistur The inspector questioned the qualification of this seal design for lack of LOCA and submergence test dat The licensee conducted LOCA and submergence testing on a penetration configuration similar to that of F0 The penetration assembly successfully passed the LOCA and submergence test with no anomalie The test results have been evaluated by the licensee and are included in EQDP 1 The test results are discussed in the Wyle and EGS Reports referenced in paragraph above. This item is now considered close (Closed)
Unresolved Item 50-261/89-26-04, Dose Rate for Hydrogen Recombiner A question was asked about the total dose the Hydrogen Recombiner Skid would see as a result of a design base accident inside containmen The master list of electrical equipment requiring environmental qualification did not include the recombiner A sample calculation was performed using the assumed 54 and 90 day reaction chamber dose rate The calculation showed that the total accident dose experienced by the recombiners would not exceed the EQ radiation threshold of 10,000 rads gamma for the required operating tim This was judged to be a mild environment for the recombiner This item is considered close. Licensee Event Reports (LERs) (Closed) LER 88-15, Inadequate Pump Motor and Power Cable Environmental Qualification Documentation Files The licensee reported that the SI and CS pump motors were not previously qualified for the post accident high radiation environment in which they would be exposed during a LOC The licensee also discovered that the room area fan coolers for the CS, SI and RHR pump
motors were not qualified for post accident radiation levels and would likely fail post accident causing elevated ambient temperatures in the SI, RHR and CS pump motor rooms. The licensee developed JCO's to allow for continued operation based on documentation which demonstrated that the motors were qualifiable. Later the licensee assembled EQ documentation for the CS pump motors and revised the qualification file for the RHR Pump motor to include the SI pump motor The licensee-evaluated the motor insulation systems to establish qualification for post accident radiation doses and service life at elevated ambient temperature The qualification for the SI and RHR pump motors was addressed in EQDP The EQDP demonstrated by analysis that the RHR and SI pump motors were qualified to perform their required safety functions after 40 years of service. The RHR pump motor was qualified to operate continuously for a minimum of 72 days post LOCA at the peak ambient temperature of 900 C. The SI pump motor was qualified to operate continuously for 52 days post LOCA at the peak ambient temperature of 102 0C. This met the 30 day operating requiremen Questions were raised about a new aging analysis performed by the licensee for the RHR pump motors at elevated temperatures. The EQDP analysis assumed operating times of 5 percent on the RHR pump motor However, actual run time data on the RHR motors indicated use was much higher than assumed in the calculation The licensee has performed additional calculations using actual run time data and has reduced the motor life at elevated temperature The licensee has indicated that the EQDP will be revised appropriately to reflect the new calculation Initial results indicated that the RHR pump motor life was closer to 42 days Post LOC This still met the 30 day operating requiremen The EQDP also showed that the RHR and SI pump motors were qualified for a total radiation dose of 2x10E8 rads gamm This met the accident dose 1.3 x 10E6 rads gamm The qualification for the CS pump motor was addressed in EQDP The analysis of the CS motor insulation system concluded that the motor was qualified for radiation environments up to a total dose of 1x1OE7 rads gamma. The calculated Post LOCA useful life for the CS pump motor at peak room temperature was 25.5 days. This fell short of the 30-day operating requiremen However, considering that the maximum ambient temperature of 213.4 0F only exists for the first 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> and then it drops to 170'F, the licensee concluded that the motor was qualified for 30 days operatio The above problems were identified by the EQ Assessment Program implemented as part of the corrective action in response to the NRC Notice of Violation and Proposed Imposition of Civil Penalty dated June 16, 1988. The licensee responded to the Notice in a letter to
NRC dated September 1, 198 This meets the NRC discretionary enforcement policy in Part 2, Appendix C for no additional enforcement sanctions. This item is close (Closed) LER 89-13, EQ Conduit Seal Deficiency Due to Inadequate Wire Use Range Installation Instructions Qualification Concerns Qualification concerns with Patel conduit seals were initially reported in NRC Inspection Report 50-261/89-26. During the inspection the licensee was asked about the allowable use ranges for the grommets and wire diameter As a result of research to respond to the NRC question, it was identified that in some applications, the conduit seal grommet had an inappropriate use range for the installation, and therefore would allow moisture to enter through the seal and into safety related electrical component The licensee inspected the seals for proper wire use rang This required some grommets to be replaced and in some cases new wire was installed or in the case of some ASCO solenoid valve configurations a low point weep hole was drilled in the conduit. The cause of the problem was attributed to inadequate installation instructions provided by the vendo The vendor's drawings only gave a maximum wire diamete This information was misinterpreted by the licensee. The vendor submitted a 10 CFR, Part 21 Notification on January 5, 1990 which further clarified the proper use range requirements for the Patel conduit seal This issue will be addressed as part of the closeout for Unresolved Item 50-261/91-03-0 Thus, any enforcement action will be addressed at that time. This item is close. Exit Interview The inspection scope and results were summarized on February 22, 1991, with those persons indicated in paragraph 1. The inspector described the areas inspected and discussed in detail the inspection results listed belo Proprietary information is not contained in this repor Dissenting comments were not received from the license (Open)
Unresolved Item 50-261/91-03-01, Evaluate LOCA/Submeregence Test Results for Qualification of Patel Conduit Seal, Paragraph. Acronyms and Initialisms ASCO - Automatic Switch Company C
- Centigrade CFR -
Code of Federal Regulations CS
-
Environmental Qualification EQDP - Environmental Qualification Documentation Package F
-
Fahrenheit
JCO
- Justification for Continued Operation LER - Licensee Event Report LOCA - Loss of Coolant Accident NPT
-
National Pipe Thread NRC - Nuclear Regulatory Commission PSIG -
Pounds Per Square Inch Gauge RHR - Residual Heat Removal SI
- Safety Injection