ML19031B532
| ML19031B532 | |
| Person / Time | |
|---|---|
| Site: | Salem  |
| Issue date: | 02/01/1978 |
| From: | Librizzi F Public Service Electric & Gas Co |
| To: | Lear G Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19031B532 (3) | |
Text
PS~G February 1, 1978 Director of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20014 Attention:
Mr. George Lear, Chief Operating Reactors Branch #3 Division of Operating Reactors
Dear Mr. Lear,
We have reviewed the incident of inadvertent injection of NaOH into the reactor coolant system as noted in your letter of September 19, 1977.
Attached is an analysis prepared by our Engineering and Con-struction Department to evaluate a Boron Dilution accident.
Based on this analysis, we conclude that a Boron Dilution incident is unlikely.
A single failure would not cause a Boron Dilution accident since the shut-off valves in the potential flow path are in a normally closed position and pumping action is required to induce flow through the flow eductors from the spray additive tank.
With regard to possible operator corrective action, the control room has tank level indication and a low-level alarm to keep him informed of the status of the spray additive tank.
In ad-dition, the status of the containment spray pumps and the shut-off valves in the flow path are identified by position lights on the operator console.
Based on the above information, we conclude that no corrective action is necessary for Salem.
Should you wish additional information, please do no hesitate to contact us.
The Energy People Very truly yours, F.~
General Manager -
Electric Production 780440065 '
95-2001 ( 400M) 9-77
r TITLE:
PURPOSE ACCIDENT A~ALYSIS, BORON DILUTION INCIDENT NO. l AND 2 UNITS SALEM NUCLEAR GENERATING STATION To evaluate a Boron Dilution Accident.
SCOPE To examine the potential for injection of the contents of the contain-ment spray sodium hydroxide tank into the Reactor Coolant System via the Residual Heat Removal System.
REFERENCES Crystal River FSAR Section 6.2 U.S. NRC Docket no. 50-272 DISCUSSION The Engineering Department has performed the evaluation and analysis req~ested by the NRC in the referenced Docket.
A Boron Dilution incident took place at the Crystal River Unit 3 plant of Florida Power Corporation.
The plant design is of Babcock and Wilcox origin; the safety injection and containment spray flow-paths are different than those at Salem.
The Crystal River Unit 3 design makes us~ of sodium hydroxide for post LOCA pH adjust~ent of borated water in the containment sump.
The outlet of the sodium hydroxide tank is connected directly to the suction lines of the Decay Heat Removal Pumps (equivalent to Salem's RHR pumps) which discharge directly to the reactor vessel.
The sodium hydroxide tank is elevated to permit gravity draining of its contents into the containment spray pump suction header.
No pumping action is required to inject the chemical.
The incident involved cycling of the sodium hydroxide tank isolation valve whi"ch subsequently allowed s6dium hydroxide to drain to the Decay Heat Removal system.
Upon initiation of coolant recirculation sodium hydroxide was injected into the reactor coolant S!YEtem.
The Salem Design consists of a 4,000 gallon sodium hydroxide tank which is connected to the recirculation line of each contaminant spray pump through an eductor.
Pumping action is required to draw the contents of the sodium hydroxide tank into the containment spray system.
y At Salem the only direct path to the RHR system would be from the containment spray pump recirculation line through the containment spray pump discharge line, through valve CS36, and to the discharge line of the RHR pumps.
This path, however, is normally isolated when the RHR system is in the RCS cooldown mode: when the path is in operation the direction of flow is from the RHR system to the contain-ment spray system.
Based upon this review, we conclude that a Boron Dilution Incident at Salem is unlikely for the following reasons:
- 1.
Two sets of shut-off valves exist in the potential flow path:
CS16 and CS17 in the sodium hydroxide tank discharge line and CS36 valves in the RHR-CS cross connect lines.
Both sets of valves are in the closed position when the RHR system is in the RCS cooldown mode.
- 2.
Test cycling, for surveillance requirements, of both sets of valves mentioned above is not simultaneous.
- 3.
Pumping action is required to obtain considerable flow through an eductor.
The containment spray pump iecirculation lines are not normally operating during RHR system RCS cooldown mode.
- 4.
The RHR system, when not operating, is isolated from the contain-ment spray system.
ACTION REQUIRED A design modification is not necessary.