ML20235U851
| ML20235U851 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/08/1987 |
| From: | Shelton D TOLEDO EDISON CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 1394, NUDOCS 8710140282 | |
| Download: ML20235U851 (3) | |
Text
,
e TOLEDO
%mmEDISON DONAU] C. SHELTON Vre prendro-Nuttrar Docket No. 50-346 License No. NPF-3 Serial No. 1394 October 8, 1987 United States Nuclear Regulatory Commission Document Control Desk Washington, D. C.
20555
Subject:
Recension Of Commitment To Install An Additional Check Valve On Each High Pressure Injection Line Gentlemen:
Under letter of May 15, 1980 (Serial No. 616), Toledo Edison submitted to the NRC a revised inservice inspection and testing program. Item I of the letter requested relief from individual closure testing for back-to-back check valves HP-59 and HP-57, HP-58 and HP-56, HP-50 and HP-48 HP-51 and HP-49.
These valves form the ASME Class 1 to Class 2 boundary on the High Pressure Injection (HPI) System. The NRC issued a safety evaluation, dated May 18, 1984 (Log No. 1521), addressing Toledo Edison's proposed relief requests. The requested relief from individual closure testing of these valves was found unacceptable; however, interim relief was granted.
The NRC Staff concluded that these valves perform a pressure isolation function between high and low pressure systems, and, although the ASME code does not clearly require individual closure testing of these valves, the Staff determined that verification of this capability was desirable and mandated augmented test requirements as provided for by 10CFR50.55a(g)
(6) (11). Toledo Edison was requested to propose an alternate interim test program and to find acceptable alternative long-term testing.
In lieu of individual closure testing of the back-to-back check valves.
Toledo Edison proposed (Serial No. 1139, dated March 29, 1985) to install a new swing check valve upstream of the back-to-back check valves with a drain point provided for leak monitoring. After this modification the two back-to-back check valves would be tested as one valve. Double isolation would be confirmed by individual leak testing of the back-to-back check valves (as a unit) and the swing check valve.
0140202 872000 G
ADOCK 05000346 PDR 1
THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISDN AVENUE TOLEDO. OHIO 43652 g
Dockat No.J50-346 i
License No. NPF-3 Serial No. 1394-Page 2:
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.I Toledo' Edison has continued to review this issue and has determined that an additional check valve to ' protect the low pressure suction of the HPI pumps is not necessary. This determination was made based on the two reasons summarized below. A detailed discussion follows the summary:
1.
The existing' valve testing program provides adequate protection for i
the low pressure HPI pumps suction piping. By this letter, Toledo Edison proposes that this testing frequency be revised consistent 1
wit'n the ASME Code for Category A valves (i.e. leak testing once per f
two years) and this testing program be made the long-term resolution 1
for. ensuring protection of the HPI pumps suction piping.
2.
Toledo Edison ~has previously resolved the generic issue of pressure
{
isolation between high and low pressure systems (high-low pressure interfaces) as a separate item with the NRC (Log No. 728, dated June 1, 1981). Based on this resolution, the back-to-back check valves were not fiantified as a high-low pressure interface.
In a February 23, 1980 letter (Log No. 523), from D. Eisenhut to All LWR Licensees, the NRC required Toledo Edison to identify all potential high-low pressure interfaces. High-low pressure interfaces were identi-fied as a generic concerm by the NRC as a result of the reactor safety study, WASH-1400. The concern involved a potential failure of the check valves isolating the high pressuro Reactor Coolant System (RCS) from low pressure system piping, resulting in a rupture of the low pressure piping'and a Loss of Coolant Accident that bypasses containment. On March 21, 1980 (Serial No. 602), Toledo Edison identified to the NRC all valve configur-ations which were considered potential high-low pressure interfaces.
The NRC, under cover letter dated June 1, 1981 (Log No. 728), transmitted a Technical Evaluation Report (TER) in response to the Toledo Edison submittal. The TER documented a Staff review of the Davis-Besse design for high-low pressure interfaces. The Staff concurred with the high-low pressure interfaces previously identified by Toledo Edison in the March 21, 1980 letter and identified no additional high-low pressure interfaces.
The Staff's review specifically included the HP1 System.
The valve configuration of the HPI System from the class break to outside contain-ment at the low pressure system interface consists of two check valves in series, one closed motor operated valve and an additional check valve downstream of the pump discharge. This valve configuration, separating the RCS from the low pressure HPI pumps suction piping, was not identified in the TER as a potential high-low pressure interface.
Toledo Edison has provided adequate assurance that the low pressure suction piping for the HPI and makeup pumps is isolated from the high pressure RCS through periodic testing.
In a series of submittals, Toledo Edison proposed to the NRC a testing program involving the check valves at
Docket No. 50-346 License No. NPF-3
)
Serial No.-1394'
.Page 3 the discharge of the HPI pumps (HP-22, 23), the motor operated valves downstream of these check valves (HP-2A, 2B, 20, 2D) and the back-to-back check valves discussed above. Also included are the check valves on the makeup injection line (MU-169) and at the discharge of the makeup pumps (MU-196, 197). The submittals are summarized below:
1.
Serial No. 1084, dated October 18, 1984:
Leak test HP-2A, B, C, D, HP-22, 23 and MU-169, 196, 197 at each cold shutdown (Mode 5) lasting more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> but not more frequently than once every three months.
2.
Serial No. 1139, dated March 29, 1985:
Toledo Edison revised its commitment to leak test valves HP-59 and HP-57, HP-58 and HP-56, HP-48 and HP-50, HP-49 and HP-51, MU-169, HP-22 and IIP-23 at each cold shutdown (Mode 5) lasting more than 72 l
hours but not more frequently than once every three (3) months.
This revised testing eliminated leak testing of the motor operated valves HP-2A, B, C, D and the makeup pump discharge check valves,.
MU-196 and MU-197.
To date, the testing has identified no leakage approaching the Technical Specification unidentified leakage limit of 1.0 gpm.
Since the NRC had previously resolved the high-low pressure interface concern as a generic item and endorsed Toledo Edison's resolution of the issue, the subsequent assignment of a high-low pressure interface to the back-to-back check valves is in apparent error.
Additionally, no ASME code requirement exists for reverse flow testing the check valves.
Therefore, individual closure testing of the existing valves should not be required nor should verification of double isolation be required at 'the
~
Class 1 to Class 2 boundary. Toledo Edison has demonstrated that the low pressure suction side of the HPI pumps is adequately protected by the existing testing program and will continue the existing testing program, at a revised frequency of once per two years, in lieu of installing additional check valves on the HPI lines.
Very tr
- yours, W'
WD:RMC pig cc: DB-1 NRC Resident Inspector A. B. Davis, Regional Administrator (2 copies)
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