ML18012A284
| ML18012A284 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 07/02/1996 |
| From: | Le N NRC (Affiliation Not Assigned) |
| To: | Robinson W CAROLINA POWER & LIGHT CO. |
| References | |
| GL-95-07, GL-95-7, TAC-M93469, NUDOCS 9607080146 | |
| Download: ML18012A284 (10) | |
Text
Mr.
W.
R. Robinson, ~e President Shearon Harris NucleM Power Plant Carolina Power 8 Light Company
~ Post Office Box 165 - Mail Code:
Zone 1
New Hill, North Carolina 27562-0165
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - GENERIC LETTER 95-07, "PRESSURE LOCKING AND THERMAL BINDING OF SAFETY-RELATED POWER-OPERATED GATE VALVES," SHEARON HARRIS NUCLEAR POWER PLANT, UNIT 1
Dear Mr. Robinson:
On August 17, 1995, the NRC issued Generic Letter (GL) 95-07, "Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves," to request that licensees take actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions.
The NRC staff is reviewing and evaluating your response to GL 95-07.
Additional information, as discussed in the enclosure, is requested in order for the staff to complete its review.
We request that you respond within 30 days from receipt of this letter.
The information requested by this letter is within the scope of the overall burden estimated in Generic Letter 95-07, "Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves," which was a maximum of 75 hours8.680556e-4 days <br />0.0208 hours <br />1.240079e-4 weeks <br />2.85375e-5 months <br /> per response.
This request is covered by Office of Management and Budget Clearance Number 3150-0011, which expires July 31, 1997.
Sincerely, (Original Signed By)
Ngoc B. Le, Project Manager Project Directorate II-1 Division of Reactor Projects I/II Office of Nuclear Reactor Regulation Docket No. 50-400
Enclosure:
Request for Additional Information cc w/enclosure:
See next page Distribution See next page DOCUMENT NAME:
G: iHARRISiHAR93469. LTR To receive a copy of this document, indicate in the box: "C" a Copy without attachment/enclosure "E" ~ Copy with attachment/enclosure "N" ~ No copy OFFICE PD21: LA Q.
PD21: PM C~
PD21: D NAME DATE EDunnin ton 96 NLe I /96 EImbro 96 6
OFFICIAL RECORD COPY 0'7 08002]
'P607080i46 960702 PDR ADOCK 05000400 P
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Mr.
W.
R. Robinson Carolina Power E Light Company CC:
Mr. William D. Johnson Vice President and Senior Counsel Carolina Power 8 Light Company Post Office Box 1551
- Raleigh, North Carolina 27602 Resident Inspector/Harris NPS c/o U.S. Nuclear Regulatory Commission 5421 Shearon Harris Road New Hill, North Carolina 27562-9998 Ms. Karen E.
Long Assistant Attorney General State of North Carolina Post Office Box 629
- Raleigh, North Carolina 27602 Public Service Commission State of South Carolina Post Office Drawer 11649
- Columbia, South, Carolina 29211 Regional Administrator, Region II U.S. Nuclear Regulatory Commission 101 Marietta St.,
N.W. Suite 2900 Atlanta, Georgia 30323 Mr. Dayne H. Brown, Director Division of Radiation Protection N.C. Department of Environmental Division of Radiation Protection Commerce 8 Natural Resources Post Office Box 27687
- Raleigh, North Carolina 27611-7687 Mr. J.
Cowan Manager Nuclear Services and Environmental Support Department Carolina Power 8 Light Company Post Office Box 1551 Mail OHS7
- Raleigh, North Carolina 27602 Shearon Harris Nuclear Power Plant Unit 1
Mr. J.
W. Donahue Plant Manager - Harris Plant Carolina Power
& Light Company Shearon Harris Nuclear Power Plant Post Office Box 165, MC: Zone 1
New Hill, North Carolina 27562-0165 Mr. Robert P. Gruber Executive Director Public Staff NCUC Post Office Box 29520
- Raleigh, North Carolina 27626 Chairman of the North Carolina Utilities Commission Post Office Box 29510 Raleigh, North Carolina 27626-0510 Mr. T.
D. Walt
- Manager, Regulatory Affairs Carolina Power E Light Company Shearon Harris Nuclear Power Plant P. 0.
Box 165, Mail Zone 1
New Hill, North Carol ina 27562-0165 Mr. Vernon Malone, Chairman Board of County Commissioners of Wake County P. 0.
Box 550
- Raleigh, North Carolina 27602 Ms.
Uva Holland, Chairman Board of County Commissioners of Chatham County P. 0.
Box 87 Pittsboro, North Carolina 27312 Mr. Milton Shymlock U.S. Nuclear Regulatory Comm.
101 Marietta Street, N.W.
Suite 2900 Atlanta, Georgia 30323-0199
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Enclosure RE VEST FOR ADDITIONAL INFORMATION SHEARON HARR S NUC EAR POW R PLANT RESPONSE TO GENERIC LETTER 95-07 "PRESSURE LOCKING AND THERMAL BINDING OF SAFETY-RELATED POWER-OPERATED GATE VALVES" 1.
Regarding valves 1CT-102, 1CT-105, Containment Sump to Containment Spray
- Pump, and 1SI-300, 1SI-301, Containment Sump to RHR Pump, the licensee's submittal states that these valves were screened for thermally induced pressure locking, but that insulating water 'is maintained in the recirculation sump by operating procedures.
The NRC staff believes that reliance on water filled containment sump piping to preclude thermally-induced pressure locking under design'asis accident conditions is uncertain.
Please provide information regarding your actions to demonstrate that water-filled piping will preclude thermally induced pressure locking of these valves for our review.
Also, please include heat transfer, thrust requirement and actuator capability calculations associated with these issues for our review.
2.
Valves 1SI-326, 1SI-327, RHR cross-tie, may be potentially susceptible to thermally-induced pressure locking caused by heat transfer from the RHR system during a design basis event.
These valves appear not to have been addressed in the licensee's submittal.
Please address this issue; 3.
Regarding valve 1SI-359, LHSI to RCS Hot Leg, the licensee's submittal states that RCS pressure could become trapped in the bonnet but this valve is
,not'pened per emergency operating procedures until approximately 6.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> into a LOCA.
The NRC staff believes that further information is required to provide assurance of the capability of this valve to perform its safety function.
Please provide detailed information regarding the licensee's dispositioning of this valve with respect to the pressure locking concern.
4.
Regarding valves ISI-86, Normal HHSI to RCS Hot Leg, and 1SI-107, Alternate HHSI to RCS Hot Leg, the licensee's submittal states that pressure locking is possible during switch over to hot leg recirculation, but that restarting a charging/safety injection pump (CSIP) will relieve it.
The NRC staff believes that reliance on restarting a
pump to relieve a potential pressure locking condition is uncertain.
This is because the valve actuator may be damaged due to operation at locked rotor conditions between the time the valve is initially called upon to open, the pressure locked condition is correctly diagnosed by operations personnel, the pump is started and the pressure in the vicinity of the valve builds up sufficiently to relieve the pressure locked condition.
Please address these issues.
5.
Valves 1SI-I, 1SI-2, BIT Inlet Isolation, and 1SI-3, 1SI-4, BIT Outlet Isolation, may become pressurized from the reactor coolant system (RCS) or the charging system during normal plant operation and experience pressure locking during a design basis depressurization.
A loss of offsite power could exacerbate these conditions.
The licensee's submittal states that these valves are not susceptible to pressure locking.
Please address these
- issues, and state why these valves are not susceptible to pressure locking.
6.
Based on a review of system diagrams, it appears that valve 1SI-52, HHSI to RCS Cold Leg, may become pressurized from the RCS during normal plant operation and experience depressurization induced (hydraulic) pressure locking during a design basis event.
Please address this issue.
In addition,'he licensee's submittal states that the locking condition does not exist during the valve's opening safety function.
Please provide additional information to clarify this wording.
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7.
Regarding valves 1RC-113,
-115, -117, PORV Block, the licensee's submittal states that these valves are closed during normal operation to isolate a
leaking PORV, but that they are required to open in response to a steam generator tube rupture accident.
The NRC staff believes that this scenario may potentially result in a pressure locking condition for these valves.
Please address this issue.
In addition, with regard to the potential susceptibility of these valves to thermal binding, the licensee's submittal states that existing plant procedures open the valve prior to cooldown.
It is unclear if this situation also applies to a case where a
PORV block valve would be shut to isolate a
leaking PORV.
It would appear that, if a PORV block valve is shut to isolate a leaking PORV, then the licensee would maintain the PORV block valve shut during plant cooldown.
It would also appear that this scenario could lead to a potential thermal binding condition if the valve is required to open for low temperature overpressure protection.
Please address these issues.
8.
Valves 1MS-70, and 1MS-72, Main Steam to AFW Turbine, may be potentially susceptible to thermally induced pressure locking if they exist in a configuration where steam condensate is permitted to enter the valve bonnet and a subsequent ambient heatup occurs, such as during a high energy line break.
Please address this issue.
9.
In Attachment 1 to GL 95-07, the NRC staff requested that licensees include consideration of the potential for gate valves to undergo pressure locking or thermal binding during surveillance testing.
During workshops on GL 95-07 in each
- Region, the NRC staff stated that, if closing a safety-related power-operated gate valve for test or surveillance defeats the capability of the safety system or train, the licensee should perform one of the following within the scope of GL 95-07:
2.
3.
4.
Verify that the valve is not susceptible to pressure locking or thermal binding while closed, Follow plant technical specifications for the train/system while the valve is closed, Demonstrate that the actuator has sufficient capacity to overcome these phenomena, or Make appropriate hardware and/or procedural modifications to prevent pressure locking and thermal binding.
The staff stated that normally open, safety-related power-operated gate valves which are closed for test or surveillance but must return to the open position should be evaluated within the scope of GL 95-07.
Please discuss if valves which meet this criterion were included in your review, and how potential pressure locking or thermal binding concerns were addressed.
10.
Through review of operational experience
- feedback, the staff is aware of instances where licensees have completed design or procedural modifications to preclude pressure locking or thermal binding which may have had an adverse impact on plant safety due to incomplete or incorrect evaluation of the potential effects of these modifications.
Please describe evaluations and training for plant personnel that have been conducted for each design or procedural modification completed to address potential pressure locking or thermal binding concerns.
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Hemorandum Dated July 2, 1996 Distributi on Docket=F-i-l e PUBLIC S.
Varga J. Zwolinski E. Dunnington N.
Eaton H. Shymlock, RII
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