ML18054A739

LER 89-007-00:on 890410,lift Setpoints for PORVs Associated W/Low Temp Overprotection Sys Exceeded Tech Spec Limit. Caused by Poor Documentation Re Liftpoint Value.Ltr of Interpretation Will Be Submitted to NRC.W/890509 Ltr

ML18054A739
Person / Time
Site:	Palisades
Issue date:	05/09/1989
From:	Johnson B, Kozup C CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-007, LER-89-7, NUDOCS 8905170099
Download: ML18054A739 (5)

Text

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,,_ .,,,,._. ry,._,nwn liMll (Ill At approximately 1500 on April 10, 1989, Plant Engineering personnel identified that the lift setpoints for the power operated relief valves (PORVs) [AB;RY] associated with the Low Temperature Overpressure Protection (LTOP) system had been set at exactly the Technical Specification (TS) limit. When instrument inaccuracies are added to the set value, the lift setpoints presented in*TS 3.1.8.1 were exceeded.

The reactor was critical with the Plant operating at 80 percent of rated power when the condition was identified . During a review of the setpoint methodology process utilized at Palisades, Plant Engineering personnel identified that PORV liftpoint had been set at the TS values of 310 and 575 psia. Setting the liftpoints at the TS value, neglecting instrument accuracies, could result in the actual lift points being 332 and 597 psia when maximum instrument inaccuracies are accounted for. A review of past performances of TS Surveillance Procedures M0-27 A through D which provide for functional testing of the LTOP system, revealed that 29 of the 31 times lift setpoints exceeded the TS limit. While the liftpoint did exceed the TS limit it was within the acceptance values provided by 10CFR50 Appendix G. :3905170099 PDR ADO CK 05000255 !5 PDC T nn"""" TTn* \\l lllllCJ-.-

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• 1 NRc Form .JSeA 19-831 -LICENSEE EVENT REPORT (LER)*TEXT CONTINUATION U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO.

EXPIRES: B/31 /85 FACILITY NAME 111 PALI SADES NUCLEAR PLANT

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NUMBER 0 15 I 0 I 0 I 0 I 21 515 8 I 9 -01017 -0 ,o 012 OF 0 f+ At approximately on April 10, 1989, Plant Engineering personnel identified that the lift setpoints for the power operated relief valves (PORVs) [AB;RV] associated with the Low Temperature Overpressure Protection (LTOP) system had been set at exactly the Technical Specification (TS) limit. When instrument inaccuracies are added to the set value, the lift setpoints presented in TS 3.1.8.1 were exceeded.

The reactor was critical with the Plant operating at 80 percent of rated power when the condition was identified.

The LTOP system provides primary coolant system (PCS) [AB] overpressure relief capability to protect the reactor vessel [AB;RPV] from the potential for brittle fracture.

The Palisades LTOP system is a two channel system which relieves PCS pressure through a PORV. Channel A relieves through PRV-1042B

[AB;RV] and channel B relieves through PRV-1043B

[AB;RV]. The system is enabled at two settings.

When the PCS cold. leg temperature is less than or equal to 300 degrees F, the lift setpoint for the PORV is less than or equal to 310 psia. When the PCS cold leg temperature is greater than 300 degrees F but less than 430 degrees F, the setpoint for PORV opening is less than or equal to 575 psia. Above 430 degrees F the LTOP system is not required to be enabled. The LTOP system setpoints are derived from Plant heatup and cooldown limits specified in TS. The setpoints reflect the temperature and pressure limits calculated according to the requirements of Appendix G to 10CFR50, using the methodology provided in Regulatory Guide 1.99, Revision 2. These setpoints were enacted with the issuance of Amendment 117 to the Palisades operating license on November 14, 1988. During a review of the setpoint methodology process utilized at Palisades, Plant Engineering personnel identified that PORV liftpoint had been set at the TS values of 310 and 575 psia. Setting the liftpoints at the TS value, neglecting instrument accuracies, could result in the actual lift points being 332 and 597 psia when maximum instrument inaccuracies are accounted for. A review of past performances of TS Surveillance Procedures M0-27 A through D which provide for functional testing of the LTOP system, revealed that 29 of the 31 times lift setpoints (310 or 575 psia) were checked, the setpoint was greater than the TS limit. While the liftpoint did exceed the TS limit it was within the acceptance values provided by lOCFR.50 Appendix G. Cause Of The Event The proximate cause of this condition is that the setpoint value which results from the addition of instrument inaccuracies is not conservative with the liftpoint specified in TS. This condition has been attributed to poor documentation within the TS regarding the specific liftpoint value. When the TS value was derived, Engineering personnel subtracted instrument

-____ _, ---.. NRC FORM 388.A ---19-831

'v . . NRC Form 31aA. !9-831 LICENSEE EVENT REPORT (LERI TEXT CONTINUATION U.I. NUCLEAll REGULATORY COMMISSION APPROVED OMB NO. 3150-010' EXPIRES: 8/31 /BS FACILITY NAME 11 l DOCKET NUM9ER 121 LU NUMeER Ill PAGE 131 PALISADES NUCLEAR PLANT 0 I 5 I 0 I 0 I 0 I 21 5 819 -0 I q 7 -°' 0 0 I 3 OF 0 I 4 TEXT l/f -_.,.ii ,.,,.,;n,d, -__,,.. NltC Fotm 1171 inaccuracies from the 10CFR50 Appendix G limit and arrived at the 310 and 575 psia setpoints found in TS. The intent of the TS liftpoint value is to ensure compliance with Appendix G. The typical setpoint methodology, if applied to this situation, would be to provide the applicable Appendix G limit in TS and then control the actual setpoint, adjusted for instrument inaccuracies, through TS Surveillance Procedures.

Corrective Action Plant Engineering personnel reviewed the basis for TS 3.1.8.1 and TS Surveillance Procedures which set the PORV lift points and verified that even if the largest positive instrument inaccuracy was added to the TS liftpoint, the 10CFR50 Appendix G limit would not be exceeded.

Upon further review it was additionally identified that the curve utilized in defining the Appendix G limit has incorporated a 30 psia measurement inaccuracy.

Therefore, a letter of interpretation will be submitted to the NRC which delineates Consumers Power's position that the 310 and 575 psia setpoints are not intended to be specific limits, but only a reference value which can be exceeded by the maximum instrument error and continue to ensure compliance with 10CFR50 Appendix G. Present TS will be modified in the future following installation of new PORVs. Analysis Of The Event The basis for TS 3.1.8.1-provides that: There are three pressure transients which could cause the PCS pressure to exceed the pressure limits required by 10CFR50 Appendix G. They are; (1) a charging/letdown imbalance, (2) the start of a high pressure safety injection (RPSI) pump, and (3) initiation of forced circulation in the PCS when the steam generator temperature is higher than the PCS temperature.

In review of pressure transients 1 and 2, analyses have been completed and administrative controls for HPSI operability have been implemented such that the PORV setpoints ensure that lOCFRSO Appendix G pressure limits will not be exceeded.

Above 430 degrees F, the pressurizer safety valves prevent 10CFR50 Appendix G limits from being exceeded by a charging/letdown imbalance.

In the case of the third pressure transient, the requirement

• that steam generator temperature be less than or equal to the PCS temperature when forced circulation is initiated in the PCS ensures that an energy addition caused by heat transferred from the secondary system to the PCS will not occur. This requirement applies only to the initiation of forced . circulation (the start of the first primary coolant pump) with one or more of the PCS cold leg temperatures less than 450 degrees F. NRC FORM 3159.A 19-831 _,,.. ___ ----

1L NAC Form 31&8.A 19-831 FACILITY NAME 111 LICENSEE EVENT REPORT (LERI TEXT CONTINUATI N OOCKET NUMaER 121 YEA" U.I. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO E)(PIRES:

8/31 /BS LEll NUMllER (Ill PAGE 131 PALISADES NUCLEAR PLANT 0 1 s I 0 I 0 I 0 I 2 15 I 5 819 -0 I q I -01 0 0 I 4 OF 0 14 TEXT 111,,,,,,._a,..,,._, --NltC Fonn.l11!6'1'111171 NRC FORM 366,Q.19-831 Therefore, as long as the liftpoint of the PORVs is less than the Appendix G pressure limit, no threat to the health and safety of the public is presented.

This event is being reported per 10CFRS0.73(a)(2)(i)(B) as an operational condition prohibited by TS. T --nnnn-, ,. 'Tl""I.,

consumers Power POWERINCi MICHICiAN'S PROCiRE55 General Offices: 1945 West Parnell Road, Jackson, Ml 49201 * (517) 788-0550 May 9, 1989 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-255 -LICENSE DPR-20 -PALISADES PLANT -LICENSEE EVENT REPORT 89-007 -POWER OPERATED RELIEF VALVES LIFTPOINT EXCEEDS TECHNICAL SPECIFICATIONS Licensee Event Report (LER)89-007 (Power Operated Relief Valves Liftpoint Exceeds Technical Specifications) is attached.

This event is reportable to the NRC per 10CFR50.73(a)(2)(i)(b).

Brian D Johnson Staff Licensing Engineer CC Administrator, Region III, USNRC NRC Resident Inspector

-Palisades Attachment OC0589-0013-NL02 A CMS *NCRGY COMPANY