ML17257A079

LTR-17-0263-1 Reply to Tom Gurdziel Regarding Scram at Oyster Creek

ML17257A079
Person / Time
Site:	Beaver Valley, Oyster Creek, Crane
Issue date:	09/14/2017
From:	Silas Kennedy NRC/RGN-I/DRP/PB6
To:	Tom Gurdziel - No Known Affiliation
Kennedy S
Shared Package
ML17192A016	List: ML17257A079
References
LTR-17-0263-1
Download: ML17257A079 (1)

Text

1 From: Kennedy, Silas Sent: Monday, September 11, 2017 4:59 PM To:tgurdziel@twcny.rr.com Cc:Pinkham, Laurie; Carrington, Kenya; Andrew s, Elizabeth; Shaffer, Steve; Safouri, Christopher

Subject:

Tom Gurdziel, Email re: Why Did They Do That? Event Number 52839 Mr. Gurdziel, Thank you for your questions you provided via an email to CHAIRMAN Resource, dated July 6, 2017. Your questions were in response to Event Number 52839 regarding Oyster Creek manual reactor scram due to degrading condenser vacuum on July 3, 2017. Please see our responses to your questions below. QUESTION No. 1: "They had to manually scram the reactor because they didn't have a dependable condenser. Then, in order to cool down the reactor they used a method that requires the main condenser. Why did they do that?" RESPONSE No. 1: On July 3, 2017, operators observed the vacuum in the main condenser degrading. Before the vacuum in the condenser degraded to a point where it would have impacted turbine operation, operators in the control room took action to recover the vacuum in the condenser. Since vacuum could not be recovered and continued to lower, the operators manually scrammed the reactor prior to the vacuum reaching a value which would have triggered an automatic shutdown of the reactor. An automatic reactor shutdown on low condenser vacuum would have also prevented the bypass valves from automatically opening, thereby protecting against an over-pressurization of the main condenser. Once the reactor was manually scrammed, the vacuum in the condenser returned to normal. Because the condenser vacuum recovered and never reached a point which would have resulted in an automatic reactor trip, the main condenser remained available to condense steam and thus cool down the reactor via the bypass valves. QUESTION No. 2: "I believe that this plant has used its isolation (emergency) condenser system to cool down the reactor at least once since the Fukushima accidents. Wasn't it available?" RESPONSE No. 2: The isolation condenser system was available during the scram; however, it was not used or needed since the flow path of steam from the reactor to the main condenser remained available and unisolated. Please let me know if you have any additional questions.

Sincerely, Silas Silas Kennedy Chief,ProjectBranch6RegionI,DivisionofReactorProjectsProvidingnuclearoversightofThreeMileIsland,BeaverValley,andOysterCreek610 3375046work301 8487065mobile