ML19210E530
| ML19210E530 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 10/29/1979 |
| From: | Schwencer A Office of Nuclear Reactor Regulation |
| To: | Mayer L NORTHERN STATES POWER CO. |
| References | |
| TAC-13038, TAC-13039, NUDOCS 7912050176 | |
| Download: ML19210E530 (7) | |
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UNITED STATES y
7, NUCLEAR REGULATOR.Y COMMISSION E
WASHINGTON, D. C. 20555 E
ok OCTOBER 2 9 1979 Docket Nos. 50-282 and 50-306
' Mr. L. O. Mayer, Manager Nuclear Support Services Northern States Power Company 414 Nicollet Mall - 8th Floor Minneapolis, Minnesota 55401
Dear Mr. Mayer:
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 detemined that a wide varia-tion exists in the number of LERS received and the technical specific:cion requirements and have, therefore, decided to clarify our requiremer'.s.
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 for Westinghouse-designed reactors. Wastinghouse 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 LC0 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 LC0 is met.
There is no difference intended in requirements issued for any Westinghouse reactor. Westinghouse has informd the NRC that all of their customers have been infomed of this and that ail the licensees should be following the same procedures regardless of the language of their Technical Specification. That is, plants with Technical Specifications written in tems 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 requi.ement 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.
1498 245 7912 050 /) b
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t-Mr. L. O. Mayer OCTOBER 2 3 1979 Northern States Power Company.
The present Westinghouse Standard Technical Specifications (Tindicated W-STS) require all fall length control rods to be positioned within i 12 steps 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 detemined that the " indicated position" requirement may.be fulfilled by voltage measurements obtained from the position. indication mecieu:: ism (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 infom 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 foms; such as (1) revising your technical specifications to limit control rod misalignment to no more than i 12 steps indicated position, (2) seeking relief by perfoming analyses justifying (with penalties if needed) greater misalignments, or (3) proposing alternate 'or supplemental monitoring specifications to demonstrate compliance with the i 12 step indicated alignment requirement.
If you have any questions on this matter, please contact us.
Sincerely
&$$V
.,u 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 1498 246
Mr. L. O. Mayer Northern States Power Company OCTOBEa p g 3;g cc:
Gerald Charnoff, Esquire Shaw, Pittman, Potts and Trowbridge 1800 M Street, N.W.
Washington, D. C.
20036 Ms. Terry Hoffman Executive Director Minnesota Pollution Control Agency 1935 W. County Road B2 Roseville, Minnesota 55113 The Environmental Conservation Library Minneapolis Public Library 300 Nicollet Mall Minneapolis, Minnesota 55401 Mr. F. P. Tic ney, P1 ant Manager Prairie Island Nuclear Generating Plant Northern States Power Company Route 2 Welch, Minnesota 55089 Joclyn F. Olson, Esquire Special Assista-t Attorney General Minnesota Pollut. ion Control Agency 1935 4. County Road B2 Roseville, Minnesota 55113 Robert L. Nybo, Jr., Chairman Minnesota-Wisconsin Boundary Area Commission 619 Second Street Hudson, Wisconsin 54016 Clarence D. Fierabend U. S. Nuclear Regulatory Commission P. O. Box 374 Red Wing, Minnesota 55066 1498 247
REACTIVITY CONTROL SYSTEMS 3/4.1.3 MOVABLE C0NTROL ASSEMBLIES GROUP HEIGHT LIMITING CONDITION FOR OPERATION 3.'l. 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 2 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 Special Test Exceptions 3.10.2 and 3.10.3.
1498 248 W-STS 3/4 1-14 007 I 373
REACTIVITY CONTROL SYSTEMS LIMITING CONDITION FOR' OPERATION (Continued) c)
A power distribution map is obtajned from the movable incore detectors and F (Z) and F a
within their limits wikhin 72 hobYs.re verified to be d)
{ither the THEkMAL 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 group with the inoperable rod are aligned to within i 12 steps of the inoperable rod within one hour while maintaining the rod sequence and insertion limits of Figures (3.1-1) and (3.1-2); the THERMAL POWER level shall be restricted pursuant to Speci-fication (3.1.3.6) during subsequent operation.
SURVEILLANCE RE0VIREMENTS 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 ltngth 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.
1498 249 W-STS 3/4 1-15 MAR 15 G77 e
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TABLE 3.1-1 ACCIDENT ANALYSES REOUIRING REEVALUATION IN THE EVENT OF AN IN0PERABLE FULL OR PART LENGTH R0D Rod Cluster Control Assembly Insertion Characteristics Rod Cluster Control Assembly Misalignment loss Of Reactor Coolant From Smali Ruptured Pipes C" From Cracks In Large Pipes Which Actuates The Emergency Core Cooling System Single Rod Cluster Control Assembly Withdrawal A+, Full Power Major Reactor Coolant System Pipe Ruptures ('.oss Of Coolant Accident)
Major Secondary System Pipe Rupture Rupture of a Control Rod Drive Mechanism Housing (Rod Cluster Control Assembly Ejection) e 1498 250 w-CTS 3/4 1-16 0CT 1 S76
REACTIVITY CONTROL SYSTEMS POSITION INDICATION SYSTEMS-OPERATING LIMITING CONDITION 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 2 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 directio'n since the last determination of the rod's position, or 2.
' Reduce THERMAL POWER TO less tiian 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 cther 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 REOUIREMENTS
'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 during 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 />.
JUL 151979 W-STS 3/4 1-17 1498 251
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