05000327/FIN-2017008-06
From kanterella
Revision as of 19:53, 20 February 2018 by StriderTol (talk | contribs) (Created page by program invented by StriderTol)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Finding | |
|---|---|
| Title | Potential Unjustified Qualified Life for ASCO Solenoid Operated Valves |
| Description | Introduction: The inspectors identified a URI to review the adequacy of the licensees justification for changing the activation energy and calculating a new qualified life for ASCO NP-1 valves assemblies. Description: The manufacturer, ASCO, conservatively established a 1.0 eV activation energy for the valve coil assemblies. The activation energy appeared to be determined by test and realistic coil failure modes. The conservative methodology used by ASCO, that used the most limiting activation energy, met the requirements in 10 CFR Part 50. By memorandum dated 8/19/2004, the nuclear utility user group for environmental qualification (NUGEQ), to which the licensee was a member, provided information supporting the use of revised activation energy values from 1.0 eV to a less limiting 1.37 eV. The memorandum (memo) specified that NUGEQ was tasked to revise the activation energy values for ASCO NP series SOVs to a less limiting one. The inspectors determined that the data and conclusions reported by NUGEQ did not appear to be justified by design control measures in accordance with 10 CFR Part 50 Appendix B Criterion III and 50.49. Adequate design control measures were specified in the Category 1 specifications established in NUREG-0588 Section 4, Aging and IEEE 323-1974 Section 6.3.3, Aging, as supplemented by RG 1.89 revision 1, Regulatory Position 5 Aging. The NUGEQ memo specified that they obtained their data through the research of information acquired from various sources. The use of the 1.37 eV value was for significantly increasing the qualified life of the ASCO coils. The inspectors are concerned that this did not meet the requirement to prove conservative extrapolations and use of the most limiting activation energies. Based on the inspectors review, NUGEQ did not demonstrate that the more limiting activation energies were unrealistic and could be discounted. The memo specified that the information NUGEQ used to derive 1.37 eV was based on emailed recollections of past DuPont testing. The DuPont email appeared to be supported by some identifiable test data, but was not quality related, was not commercial grade dedicated, and performed without any identifiable design control measures. In addition, the memo disregarded other coil components with more limiting activation energies by discounting the failure modes associated with them and the coil. The manufacturer ASCO found these discounted failure modes relevant to the coil safety functions. The inspectors are concerned that the licensee disregarded realistic, more limiting, failure modes without proper justification. The design control requirements in NUREG-0588 Section 4(5) specified, in part, that known material phase changes and reactions should be defined to insure that no known changes occur within the extrapolation limits, (staff position: claims that conservative extrapolation limits have been implemented must be supported), and Section 4(6) required, the aging acceleration rate used during qualification testing and the basis upon which the rate was established should be described and justified, (staff position: testing of the equipment should be conducted using the most limiting (lowest) activation energy of the components). Additionally, RG 1.89, Environmental Qualification of Certain Electric Equipment Important to Safety for Nuclear Power Plants, Revision 1, Regulatory Position 5.c, Section 6.3.3, Aging, of IEEE Std. 323-1974, specified, in part, that the aging acceleration rate and the basis upon which it was established be described, documented, and justified. The licensee has captured these concerns in their corrective action program as CR 1366020. The inspectors need to review the licensees analysis and justification for discounting realistic failure modes, changing the activation energy, and calculating a new qualified life for ASCO NP-1 valves assemblies. This URI is opened to determine if the performance deficiency for not providing adequate justification for changing the activation energy, is more than minor. (URI 05000327/2017008-06, 05000328/2017008-06, Potential Unjustified Qualified Life for ASCO Solenoid Operated Valves) |
| Site: | Sequoyah  |
|---|---|
| Report | IR 05000327/2017008 Section 1R21 |
| Date counted | Dec 31, 2017 (2017Q4) |
| Type: | URI: |
| cornerstone | No Cornerstone |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21N |
| Inspectors (proximate) | T Fanelli M Greenleaf C Franklin S Walker |
| INPO aspect | |
| ' | |
Finding - Sequoyah - IR 05000327/2017008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Sequoyah) @ 2017Q4
Self-Identified List (Sequoyah)
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||