ML19320B188
| ML19320B188 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 05/21/1980 |
| From: | Pilant J NEBRASKA PUBLIC POWER DISTRICT |
| To: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| References | |
| IEB-80-07, IEB-80-7, NUDOCS 8007100016 | |
| Download: ML19320B188 (2) | |
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STATE May 21, 1980 Mr. Karl V. Seyfrit, Director U.S. Nuclear Regulatory Commission Office of Inspection and Enforcement Region IV 611 Ryan Plaza Suite 1000 Arlington, Texas 76011
Subject:
IE Bulletin 80-07 BWR Jet Pump Assembly Failure
Reference:
J. M. Pilant (NPPD) to K. V. Seyfrit (NRC) letter dated May 5,1980, same subject
Dear Mr. Seyfrit:
Reference (1) notified you of our favorable jet pump assembly inspection results.
The subject bulletin outlined a surveillance testing program to be established during jet pump operation.
The purpose of this sur-veillance program was early identification of jet pump assembly failure.
Paragraph B.2.b of the bulletin stated three tests be performed to determine jet pump operability:
If any of the following deviations occur during surveillance, evaluate and record the reason:
(1) The recirculation pump flow differs by more than 10% from the established speed-flow characteristics for that pump.
(2) The indicated total core flow is more than 10% greater than the core flow value derived from established power-core flow relationships.
(3) The diffuser to lower plenum differential pressure reading on an individual jet pump exceeds the expected characteristics established for that pump.
The Cooper Nuclear Station Technical Specifications concerning jet pump operability reads:
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- >.o Mr. Karl V. Seyfrit May 21, 1980 Page 2.
Whenever there is recirculation flow with the reactor in the start-up or run modes, jet pump operability shall be checked daily by verifying that the following conditions do not occur simultan-eously:
a.
The recirculation pump flow differs by more than 15% from the established speed flow characteristics.
b.
The indicated value of core flow rate varies from the value derived from loop flow measurenents by more than 10%.
c.
The diffuser to lower plenum differential pressure reading on an individual jet pump varies from the mean of all jet pump differential pressures by more than 10%.
Since IEB 80-07 was issued, the General Electric Company (GE) and Commonwealth Edison Company (CECO) have meet with the NRC to discuss jet pump assembly failure and a recommended surv:illance program.
The surveillance program recommended by GE involves obtaining a jet pump loop signature at various flow rates.
This signature identifies the in-dividual jet pump's differential pressure with respect to the average jet pump differential pressure for that loop.
This data is used to determine whether an individual pump has failed when the ratio of jet pump loop flow to recirculation pump flow falls outside its expected range. The ratio is plotted daily.
Cooper Station will perform the surveillance required by its Technical Specifications and that recommended by the General Electric Company rather than the program outlined in IEB 80-07.
The repeatability of the GE test program is higher and would give us more confidence in identi-fying a failure.
In addition, our Technical Specification requirements require that we monitor individual jet pump differential pressures daily. We believe this surveillance program is a better one than that outlined in the bulletin.
Since issuance of the bulletin, Cooper Station has been shutdown for a refueling and maintenance outage.
We will institute this surveillance program during startup from the outage.
Should you have any questions, please contact me.
Sincerely, J... Pilant Director of Licensing and Quality Assurance JMP:PJB:cg