EN Revision Imported Date : 2/27/2020
EN Revision Text: PART 21 REPORT - POTENTIAL DEVIATION OF PRESSURE TRANSMITTERS DUE TO TEMPERATURE RISE
The following information was received from Emerson Rosemount Nuclear Instruments, Inc. via fax:
"Rosemount Nuclear Instruments, Inc. (RNII) is providing an interim evaluation report on the treatment of temperature rise due to electronics self-heating in qualified life thermal aging calculations on Model 1153 and 1154 [inclusive of 1153 Series B, 1153 Series D, 1154, and 1154 Series H] pressure transmitters. The evaluation is being conducted to determine if modifications to the currently specified qualified life are warranted.
"Qualification programs for 1153 and 1154 pressure transmitters were structured to comply with the requirements of IEEE standard 323-1974 which requires aging to establish a qualified life prior to design basis event testing. Thermal aging is considered a significant aging mechanism; therefore, accelerated thermal aging was conducted on type test specimens as described in RNII qualification reports D8300040 and D8700096. These reports document the thermal aging basis for all 1153 and 1154 models identified in section 1.0. In both type test programs, temperature rise due to electronics self-heating was present during thermal aging and was consistent with expected in service normal operating conditions.
"These evaluations are expected to be complete by February 28, 2020.
"If there are any questions, or you require additional information related to this issue, please contact Nathan Schukei (952) 949-5213 or Paul Schmeling (952) 949-5359."
There are currently no known affected customers.
* * * UPDATE ON 2/26/20 AT 1454 EST FROM JEFF CHIVERS TO KERBY SCALES * * *
The following is a summary of the information provided by the vendor via fax:
"Rosemount Nuclear Instrument Inc. (RNII) analysis of both 1150 series and 3150 series included electronics thermal imaging to characterize the thermal distribution on electronic assemblies, as well as direct in situ temperature measurements of qualified life limiting components. Specifically, temperature measurements were taken on limiting components to quantify actual temperature rise for both the original qualification accelerated aging conditions as well as for normal operating conditions.
"The analysis demonstrates that temperature rise due to electronics self-heating on limiting components is application dependent. As a result, the calculated qualified life will be application dependent. In many application conditions, the originally established qualified life calculations will remain conservative with respect to the updated calculations (i.e. the updated qualified life will be longer than the originally established qualified life). In applications where the originally established qualified life calculations may not be conservative (i.e. the updated qualified life will be shorter than the originally established qualified life), RNII believes there is no impact to the safety function of either the 1150 series or 3150 series pressure transmitters due to any difference in calculated qualified life because long term aging information obtained from the limiting component supplier, supported by RNII independent internal testing, demonstrates insignificant change over time in the electrical parameters of the limiting components for the temperatures and operating conditions in question.
"To provide a more accurate model to account for electronics temperature rise in Arrhenius calculations, RNII is revising our temperature inputs into the Arrhenius accelerated aging calculation methodology for both 1150 series and 3150 series pressure transmitters. This revised methodology will be provided separately to end users.
"RNII does not believe this issue presents a risk to the safety function of the 1150 and 3150 series pressure transmitters. RNII recommends end users evaluate the significance of this notice to their specific pressure transmitter applications. If there are any questions, please contact our Technical Support Engineers at 952-949-5200 (RNll.firstname.lastname@example.org) or Nathan Schukel at 952-949-5213."
Notified R1DO (Ferdas), R2DO (Davis), R3DO (Orth), R4DO (Kozal), and Part 21/50.55 Reactors, Part 21 Materials, NMSS _Events via e-mail.