ML14184A128
| ML14184A128 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 10/29/1979 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Jackie Jones Carolina Power & Light Co |
| References | |
| NUDOCS 7912050165 | |
| Download: ML14184A128 (9) | |
Text
OCTOBER 2 9 1979 Docket No. 50-261 Mr. J. A. Jones Senior Executive Vice President Carolina Power and Light Company CK 336 Fayetteville Street Raleigh, North Carolina 27602
Dear Mr. Jones:
The staff has recently completed a review of the LER's and Technical Specification requirements related to the Control Rod Position Indication Systems (RPI) at Westinghouse PWRs. We have determined that a wide varia tion exists in the number of LERS received and the technical specification requirements and have, therefore, decided to clarify.our requirements.
At the time of development of the Standard Technical Specifications, a systematic attempt was made to clarify potentially ambiguous specifications.
One such specification was the control rod misalignment specification fdr Westinghouse-designed reactors.
Westinghouse has performed.safety analyses for control rod misalignment up to 15 inches or 24 steps (one step equals 5/8 inch).
Since analysis of misalignments in excess of this amount have not been submitted, we have imposed an LCO restricting continued operation with a misalignment in excess of 15 inches. Because the analog control rod position'indication system has.an uncertainty of 7.5 inches (12 steps), when an indicated deviation of 12 Steps exists, the actual misalignment may be 15 inches. This is-because one of the coils, spaced at 3.75 inches, may be failea without the operator knowing about it.
The Standard Technical Specifications were written to eliminate any confusion about this, and allow a deviation of up to 12 indicated steps.
Surveillance requirements, on the indication accuracy of 12 steps were also prepared to ensure that the 15 inch LCO -is met.
There is no difference intended in requirements issued for any Westinghouse reactor.
Westinghouse has informed the NRC that all of their customers have been informed of this and that all the licensees should be following the same procedures regardless of the language of their Technical Specification. That is-plants with Technical Specifications written in terms of 15 inch misalign ment should be considering the 12 step instrument inaccuracy when monitoring rod position.
A related problem is that the installed analog control rod position indicating system equipment may not, in some areas, be adequate to maintain the control rod misalignment specification requirement because of drift problems in the calibration curves. This is evidenced by numerous LER.s concerning rod position indication accuracy. In these cases, the uncertainty may be more than 12 steps.
DF ATE NRc FR 1
(o 9 76)- NcM o2 o pu.S. GOVERCNMENT PRINTING OFFICE: 1979-289-369
Mr. J. A. Jones Carolina Power and Light Compan/y
- 2 The present Westinghouse Standard Technical Specifications (W-STS) require all full length control-rods to be positioned within + 12 steps {indicated position) of their group step counter demand position.
Since numerous problems have developed in signal conditioning circuits for display indication of control rod position, the staff has determined that the "indicated position" requirement may be fulfilled by voltage measurements obtained from the position indication mechanism (and therefore no LER need be submitted) provided a sufficient data base has been established to ensure a correlation between voltage and position.
A copy of the current, applicable W-STS Specifications (3/4.1.3.1 and 3/4.1.3.2) are.attached for your information and consideration.
It is requested that you review your present technical specifications to ensure that-the control rods are required to be maintained within + 12 steps indicated and that the rod position indication system is verified to be accurate to within 12 steps. If your review indicates that this is not the case, you should so inform the Commission within 30 days of your.receipt of this letter together with your plans to correct the deficiencies.
Any~needed corrective actions may take severial forms; such as (1)'revising your technical specifications to limit control rod misalignment to no more than + 12 steps indicated position, (2) seeking relief by performing analyses justifying (with.penalties if needed) greater-misalignments, or (3)
.proposing alternate or supplemental monitoring specifications to demonstrate compliance with the + 12 step indicated alignment requirement.
If you have any questions on this matter, please contact us.
Sincerely, A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors Enclosure W-STS Specifications 3/4.1.3.1 and 3/4.1.3.2 cc: w/enclosure See next page OFFICE DORi9 DOR:ORB SURNAME... b o s...A.S.
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OFFICE 1979-2 NRC FORM 318 (9-76) NRCM 0240
_US.GOV\\ErNMENT PRI NTING OFFICE: 1979-289-369
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pR RE~o PA UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 t!t 4PT"E 29 1979 Docket No.
50-261 Mr. J. A. Jones Senior Executive Vice President Carolina Power and Light Company 336 Fayetteville Street Raleigh, North Carolina 27602 Dear Mr.
Jones:
The staff has recently completed a review of the LER'.s and TechnitCal Specification requirements related to the Control Rod Position Indication Systems (RPI) at Westinghouse PWRs. We have determined that a wide varia tion exists in the number of LERS received and the technical specification requirements and have, therefore, decided to clarify our requirements.
At the time of development of the Standard Technical Soecifications, a systematic attempt was made to clarify potentially ambiguous specifications.
One such specification was the control rod misalign.ment specification for Westinghouse-designed reactors. Westinghouse has perforned safety analyses for control rod misalignment up to 15 inches or 24 steps (one step equals 5/8 inch).
Since analysis of misalignments in excess of this amount have not been submitted, we have imposed an LCO restricting continued operation with a misalignment in excess of 15 inches.
Because the analog control rod position indication system has an uncertainty of 7.5 inches (12 steps), when an indicated deviation of 12 steps exists., the actual misalignment may be 15 inches. This is because one of the coils, spaced at 3.75 inches, may be failed without the operator knowing about it. The Standard Technical Specifications were written to eliminate any confusion about this, and allow a deviation of up to 12 indicated steps. Surveillance requirements, on the indication accuracy of 12 steps were also prepared to ensure that the 15 inch LCO is met.
There is no difference intended in requirements issued for any Westinghouse reactor. Westinghouse has informed the NRC that all of their customers have been inforned of this and that all the licensees should be following the same procedures regardless of the language of their Technical Specification. That is, plants with Technical Specifications written in terms of 15 inch misalign ment should be considering the 12 step instrument inaccuracy when monitoring:
rod position.
A related problem is that the installed analog control rod Position indicating system equipment may not, i n some areas, be adecuate to Mintain the control rod misalignment specification requirement because c, crift prooiems in the calibration curves. This is evidenced by numerous LER's concerning rod position indication accuracy.
In these cases, the uncertainty may De more than 12 steps.
7912050 m
Mr. J. A. Jones Carolina Power and Light Company T-2R 7
The present Westinghouse Standard Technical Specifications (W-STS) require all full length control rods to be positioned within + 12 steps Tindicated position) of their group step counter demand position. Since numerous problems have developed in signal conditioning circuits for display indication of control rod position, the staff has determined that the-"indicated position" requirement may be fulfilled by voltage measurements obtained from the position indication mechanism (and therefore no LER need be submitted) provided a sufficient data base has been established to ensure a correlation between voltage and position.
A copy of the current, applicable W-STS Specifications (3/4.1.3.1 and 3/4.1.3.2) are attached for your information and consideration.
It is requested that you review your present technical specifications to ensure that the control rods are required to be maintained within j 12 steps indicated.
and that the rod position indication system is verified to be accurate to within 12 steps. If your review indicates that this is not the case, you should so inform the Commission within 30 days of your receipt of this letter together with your plans to correct the deficiencies.
Any needed corrective actions may take several forms; such as (1) revising your technical specifications to limit control rod misalignment to no more than + 12 steps indicated position, (2) seeking relief by performing analyses justifying.(with. penalties if needed) greater misalignments, or (3) proposing alternate or supplemental monitoring specifications to demonstrate compliance with the + 12 step indicated alignment requirement.
If you have any questions on this matter, please contact us.
Sincerely, A. Schwencer, Chief Operating Reactors Branch #1 Division of Operating Reactors
Enclosure:
W-STS Specifications 3/4.1.3.1 and 3/4.1.3.2 cc:
w/enclosure See next page
Mr. J. A. Jones Carolina Power and.Light Company
- 3 cc: G. F. Trowbridge, Esquire Shaw, Pittman, Potts and Trowbridge 1800 M Street, N.W.
Washington, D. C. 20036 Hartsville Memorial Library Home and Fifth Avenues
/
Hartsville, South Carolina 29550 Michael C. Farrar, Chairman Atomic Safety and Licensing Appeal Board Panel U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Richard S. Salzman Atomic Safety and Licensing Appeal Board Panel U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Dr..W.
Reed Johnson Atomic Safety and Licensing Appeal Board Panel U. S. Nuclear Regulatory Commission Washington, D. C. 20555
REACTIVITY CONTROL SYSTEMS 3/4.1.3 MOVABLE CONTROL ASSEMBLIES GROUP HEIGHT LIMITING CONDITION FOR OPERATION 3.-1.3.1 All full length (shutdown and control) rods, and all part length -rods which are inserted in'the core, shall be OPERABLE and positioned within +/- 12 steps (indicated position) of.their group step counter demand position.
APPLICABILITY:
MODES 1* and 2*
ACTION:
- a. With one or more full length rods inoperable due to being.immovable as a result of excessive friction or mechanical interference or known to be untrippable, determine that the SHUTDOWN MARGIN require ment of Specification 3.1.1.1 is satisfied within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
- b.
With more than one full or part length rod inoperable or misaligned from the group step counter demand position by more than +/- 12 steps (indicated position), be in HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
C. With one full or part length rod inoperable due to causes other than addressed *by ACTION a, above, or misaligned from its group step counter demand height by more than +/- 12 steps (indicated position),
POWER OPERATION may continue provided that within one hour either:
- 1. The rod is restored to OPERABLE status within the above alignment requirements, or
- 2. The rod is declared inoperable and the SHUTDOWN MARGIN requirement of Specification 3.1.1.1 is satisfied. POWER OPERATION may then continue provided that:
a) A reevaluation of.each accident analysis of Table 3.1-1 is performed within 5 days; this reevaluation shall confirm that the previously analyzed results of these accidents remain valid for the duration of operation under these conditions.
b) The SHUTDOWN MARGIN requirement of Specification 3.1.1.1 is determined at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
'See SDecial Test Exceptions 3.10.2 and 3.10.3.
~ 'OCT 5
REACTIVITY CONTROL 5 STEMS LIMITING CONDITION FOR OPERATION (Continued) c) A power distribution map is obta net from the movable incore detectors and F (Z) and F are verified to be within their limits within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
d) ither the THERMAL POWER level is reduced to less than or equal to-75% of RATED THERMAL POWER within one hour and within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> the high neutron flux trip setpoint is reduced to less than or equal to 85% of RATED THERMAL POWER, or e)
The remainder of the rods in the crouc with the inoperable rod are aligned to within +/- 12 steps cf the inoperable rod within one hour while maintaining the rod sequence and insertion limits of Figures (3.1-1) and (2.1-2); the THERMAL POWER level shall be restricted pursuant to Speci fication (3.1.3.6) during subsequen. coeration.
SURVEILLANCE REQUIREMENTS 4.1.3.1.1 The position of each full and part length rod shall be determined to be within the group demand limit by verifying the individual rod positions at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> except during time intervals when the Rod Position Deviation Monitor is inoperable, then verify the group positions at least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
4.1.3.1.2 Each full length rod not fully inserted and each part length rod which is inserted in the core shall be determined to be OPERABLE by movement of at least 10 steps in any one direction at least once per 31 days.
W-ST 3/4.1 -1 4
1 5 1177
TABLE 3.1-1 ACCIDENT ANALYSES REQUIRING REVA ATON IN THE EVENT OF AN INOPERABLE FULL RPA:T LENGTH ROD Rod Cluster Control Assembly Insertion Characteristics Rod Cluster Control Assembly Misalignment Loss Of Reactor Coolant From Small Ruptured P.ipes Or From Cracks In Large Pipes Which Actuates The Emergency Core Cooling System Single Rod Cluster Control Assembly Withdrawal At Full Power Major Reactor Coolant System Pipe Ruptures (Loss Of Coolant Accident)
Major Secondary System Pipe Rupture Rupture of a Control Rod Drive Mechanism Housing (Rod Cluster Control Assembly Ejection)
,~~~1 T
0" 1' C
1975
REACTIVITY CONTROL SYSTEMS POSITION INDICATION SYSTEMS-OPERATING LIMITING CONOITION FOR,OPERATION 3.1.3.2 The shutdown, control and part length control rod position indication system and the demand position indication system shall be OPERABLE and capable of determining the control rod positions within +/- 12 steps.
APPLICABILITY:
MODES 1 and 2.
ACTION:
- a. With a maximum of one rod position indicator per bank inoperable either:
- 1. Determine the position of.the non-indicating rod(s) indirectly by the movable incore detectors at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and immediately after any motion of the non-indicating rod which exceeds 24 steps in one direction since the last determination of the rod's position, or
- 2. Reduce THERMAL POWER TO-less than 50% of RATED THERMAL POWER within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
- b. With a maximum of one demand position indicator per bank inoperable either:
- 1. Verify that all rod position indicators for the affected bank are OPERABLE and that the most withdrawn rod and the least withdrawn rod of the bank are within a maximum of 12 steps of each other at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, or
- 2. Reduce THERMAL POWER to less than 50% of RATED THERMAL POWER within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />.
SURVEILLANCE REQUIREMENTS 4.1.3.2 Each rod position indicator shall be determined to be OPERABLE by verifying that the demand position indication system and the rod position indication system agree within 12 steps at least once per 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> except durina time intervals when the Rod Position Deviation Monitor is inoperable, then compare the demand position indication system and the rod position indica tion system at least once per 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
W-S7S 3/4 1-17 JUL 15 79