ML20236G302

CRD Partial Scram Test Results & Max Daily Temp Rept, 870703-30

ML20236G302
Person / Time
Site:	Fort Saint Vrain
Issue date:	07/30/1987
From:	Ronald Burrows, Novachek F, Robert Williams PUBLIC SERVICE CO. OF COLORADO
To:	Calvo J NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM), Office of Nuclear Reactor Regulation
References
P-87273, TAC-61601, NUDOCS 8708040199
Download: ML20236G302 (7)

Text

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l P-87273  ;

Attachment 1 I l

CONTROL R00 DRIVE PARTIAL SCRAM l TEST RESULTS AND MAXIMUM DAILY TEMPERATURE REPORT l

REPORT PERIOD-  !

JULY 3, 1987 - JULY 30, 1987 t

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i Prephred by: eI 6 sew /

' R. L. ' Burrows  !

Senior Plant Engineer I Approved by:

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lechnical/ Administrative l Services Manager  ;

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l Public S?rvice Company of Colorado Fort St. Vrain Unit No. 1

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P-87273 l Attachment i 1 page 3 j l

I I. ABSTRACT j i

This report summarizes the partial scram test results af.d the j maximum ti8ily temperature of those control rods with motor I temperatures above 215 degrees Fahrenheit. It is prepared to  !

satisfy the Fort St. Vrain Interim Technical Specification l Surveillance Requirement 4.1.1.A.1.a. The time period covered by j this report is July 3,1987 through July 30, 1987.

I II. BACKGROUND I Because proper operatien of the Control Rod Drive Mechanism .

(CRDM) is critical for safe operation of the reactor, a series of )

qualification tests were conducted over a one year time span to j demonstrate $ts capability. The motor temperature during these I tests varied between 200 degrees Fahrenheit and 230 degrees i Fahrenheit, and averaged 215 degrees Fahrenheit. A total of 130,000 jog cycles plus 1600 scrams was icgged during the final design testing, which is many times that enected over the normal life of a CRDM. The operating temperature of the CRDM is' limited by the trotor insulation which is rated for 272 degrees Fahrenheit ,

I to account for motor temperature rise, frictional torque j l

increase, and winding life expectancy. ^

1

In order to monitor CRDM temperatures, Resistance Temperature l Devices (RTD's) are mounted on the closure piate, orifice valve motor plate, and CRDM motor as shewn on Figure 1. All CRDM's installed in the reactor are equipped with RTD's. Three recorders locatad in the control room record each of these temperat-ures for all 37 CRDM's. CRDM motor temperatures are alarmed at 212 degrees Fahrenheit and 247 degrees Fahrenheit.

CRDM motor temperatures 2.re monitored at least onue per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to verify that they are less than 250 degrees Fahrenheit, which is a limiting condition for operation. If one or more CRDM motor temperature (s) is found to be greater than 215 degrees Fahrenheit during the daily surveillance, the motor temperature of all CRDM's exceeding 215 degrees Fahrenheit is recorded and a partial

. scram test is performed on the CRDM with the highest motor temperature once per 24 houes. These surveillance ensure that l

CRDM motor temperatures exceeding 215 degrees Fahrenheit do not degrade the CRDM's reliability to perform its design function when required.

P-87273 Attachment 1 l Page 2 III.

SUMMARY

OF RESULTS CRDM motor temperatures exceeded 215 degrees Fahrenheit for two intervals during this report period. The first interval was from July 3, 1987 through July 11, 1987. The second ,

interval was from July 17, 1987 through July 21, 1987. Since j the daily scram surveillance is performed only when CRDM motor  !

temperatures exceed 215 degrees Fahrenheit, data is presented l for these two intervals only. l 1

The partial scram test results and maximum daily temperature  ;

of those CRDM's with motor temperatures above 215 degrees  !

Fahrenheit are presented on Table 1. The pertinent parameters presented are: reactor region involved, control rod position, maximum daily motor teinperature, extrapolated scram times j (surveillance value and Back EMF calculated val ue') and  ;

starting acceleration. The control rod position is presented because of its relationship to available starting torque which affects the starting acceleration and extrapolated scram time calculated by surveillance. The surveillance extrapolated scram time is affected by control rod position because it is calculated using distance travelled versus time. Since the acceleration is slovar at lower contrcl rod positions, a  ;

longer period of time is required to reach steady state speed. '

This longer acceleration period results in a decrease in I

distance travelled over a given period of time, and thereby indicating a longer extrapolated scram time. The extrapolated scram time calculated by the Back EMF program applies a correction factor to provide a projected full length scram time. Therefore, the surveillance scram times can only be compared for trends if the control rod position is approximately the same. The Back EMF calculated scram time is mote readily trended since the value should be independent of control rod position.

The starting acceleration values presente:1 represent those calculated by the Back EMF program. These values reflect the CRDM's freedom of rotation to accelerate to steady state soeed and therefore are considered to be valuable performance I

indicators. Two values are presented: The actual-acceleration measured during a scram from the indicated control rod position, and the projected acceleration, if the control rods were at the full out position (greater than 188 inches). If the control rod position is greater than 188 inches, no data is presented for a projected starting i acceleration since the actual and projected are the same. As indicated with scram times, the projected starting acceleration is more readily trended since the value should be independent of control rod position.

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I P-87273 Attachment 1-Page 3  !

i IV. CONCi.USIONS The performance of CRDM's with motor temperatures in excess of 215 degrees Fahrenheit did not show any significant trends or .,

degradation during this report period. Therefore, it is '

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concluded that CRDM motor temperatures exceeding 215 degrees Fahrenheit did nct degrade the CRDM's reliability to perform ,

its design function when required, i i

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July.30, 1987 Fort St. Vrain Unit No. 1 P-87273 U.S. Nuclear Regulatory. Commission ATTN: Document Control Desk Washington, D.C. 20555 Attention: Mr. Jose A. Calvo Director, Project Directorate IV Docket No. 50-267

SUBJECT:

CONTROL R0D DRIVE PARTIAL SCRAM TEST RESULTS AND MAXIMUM DAILY TEMPERATURE REPORT

Dear Mr. Calvo:

The Fort St. Vrain Interim Technical Specifications (Surveillance Requirements, Section 4.1.1.A.1.a) require that a report be provided to the NRC at least once every 31 days when one or more Control Rod Drive (CRD) motor temperature (s) exceeds 215 degrees Fahrenheit. A report on the partial scram test' results and the maximum daily temperature of those CRD's with motor temperatures above 215 degrees Fahrenheit is included as Attachment 1 for your review.

We hope you will find this submittal responsive to your concerns. If you have any questions or comments, please contact Mr. M. H. Holmes at (303) 480-6960.

Sincerely, 0.0. UAWw.

R. O. Williams Vice President Nuclear Operations R0W:RLB/bj Attachment cc: Regional Administrator, Region IV Attention: Mr. J. E. Gagliardo, Chief Reactor Projects Branch cc: Mr. R. E. Farrell Senior Resident Inspector Fort St. Vrain l.

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