diff --git a/numass-main/build.gradle b/numass-main/build.gradle
index 67f23570..fe0c64f9 100644
--- a/numass-main/build.gradle
+++ b/numass-main/build.gradle
@@ -39,5 +39,13 @@ task workspace(dependsOn: classes, type: JavaExec) {
     args "-c \"D:\\Work\\Numass\\sterile2016\\workspace.groovy\" numass.fitsum sum_down".split()
     description "Run workspace task"
     group "numass"
+}
 
+task repl(dependsOn: classes, type: JavaExec) {
+    main 'inr.numass.LaunchGrindShell'
+    classpath = sourceSets.main.runtimeClasspath
+    description "Start Grind repl"
+    standardInput = System.in
+    standardOutput = System.out
+    group "numass"
 }
\ No newline at end of file
diff --git a/numass-main/src/main/groovy/inr/numass/LaunchGrindShell.groovy b/numass-main/src/main/groovy/inr/numass/LaunchGrindShell.groovy
new file mode 100644
index 00000000..d82ae2c1
--- /dev/null
+++ b/numass-main/src/main/groovy/inr/numass/LaunchGrindShell.groovy
@@ -0,0 +1,12 @@
+package inr.numass
+
+import hep.dataforge.grind.GrindShell
+
+/**
+ * Created by darksnake on 29-Aug-16.
+ */
+
+GrindShell shell = new GrindShell()
+shell.launcher.withSpec(NumassWorkspaceSpec)
+shell.launcher.from(new File("D:\\Work\\Numass\\sterile2016\\workspace.groovy"))
+shell.start()
diff --git a/numass-main/src/main/java/inr/numass/utils/ExpressionUtils.java b/numass-main/src/main/java/inr/numass/utils/ExpressionUtils.java
index 4502ac0d..50557a8a 100644
--- a/numass-main/src/main/java/inr/numass/utils/ExpressionUtils.java
+++ b/numass-main/src/main/java/inr/numass/utils/ExpressionUtils.java
@@ -7,18 +7,21 @@ package inr.numass.utils;
 
 import groovy.lang.Binding;
 import groovy.lang.GroovyShell;
-import java.util.Map;
+import groovy.lang.Script;
+import hep.dataforge.utils.CommonUtils;
 import org.codehaus.groovy.control.CompilerConfiguration;
 import org.codehaus.groovy.control.customizers.ImportCustomizer;
 
+import java.util.Map;
+
 /**
- *
  * @author Alexander Nozik
  */
 public class ExpressionUtils {
+    private static Map<String, Script> cache = CommonUtils.getLRUCache(100);
+    private static GroovyShell shell;
 
-    public static double evaluate(String expression, Map<String, Object> binding) {
-        Binding b = new Binding(binding);
+    static {
         // Add imports for script.
         ImportCustomizer importCustomizer = new ImportCustomizer();
         // import static com.mrhaki.blog.Type.*
@@ -26,8 +29,20 @@ public class ExpressionUtils {
 
         CompilerConfiguration configuration = new CompilerConfiguration();
         configuration.addCompilationCustomizers(importCustomizer); // Create shell and execute script.
+        shell = new GroovyShell(configuration);
+    }
 
-        GroovyShell shell = new GroovyShell(b,configuration);
-        return ((Number) shell.evaluate(expression)).doubleValue();
+    private static Script getScript(String expression) {
+        return cache.computeIfAbsent(expression, expr -> shell.parse(expr));
+    }
+
+
+    public static double evaluate(String expression, Map<String, Object> binding) {
+        synchronized (cache) {
+            Binding b = new Binding(binding);
+            Script script = getScript(expression);
+            script.setBinding(b);
+            return ((Number) script.run()).doubleValue();
+        }
     }
 }
diff --git a/numass-main/src/main/java/inr/numass/utils/TritiumUtils.java b/numass-main/src/main/java/inr/numass/utils/TritiumUtils.java
index 4d2b348f..13f118e2 100644
--- a/numass-main/src/main/java/inr/numass/utils/TritiumUtils.java
+++ b/numass-main/src/main/java/inr/numass/utils/TritiumUtils.java
@@ -20,15 +20,12 @@ import hep.dataforge.tables.ListTable;
 import hep.dataforge.tables.Table;
 import inr.numass.data.SpectrumDataAdapter;
 import inr.numass.storage.NMPoint;
-import static java.lang.Math.abs;
-import static java.lang.Math.exp;
-import static java.lang.Math.sqrt;
+import org.apache.commons.math3.analysis.UnivariateFunction;
+
 import java.util.HashMap;
 import java.util.Map;
-import org.apache.commons.math3.analysis.UnivariateFunction;
-import static java.lang.Math.abs;
-import static java.lang.Math.abs;
-import static java.lang.Math.abs;
+
+import static java.lang.Math.*;
 
 /**
  *
@@ -82,8 +79,7 @@ public class TritiumUtils {
      * Integral beta spectrum background with given amplitude (total count rate
      * from)
      *
-     * @param energy
-     * @param countRate
+     * @param amplitude
      * @return
      */
     public static UnivariateFunction tritiumBackgroundFunction(double amplitude) {
@@ -134,7 +130,6 @@ public class TritiumUtils {
      *
      * @param point
      * @param expression
-     * @param countRate
      * @return
      */
      public static double evaluateExpression(NMPoint point, String expression) {
diff --git a/numass-main/src/main/java/inr/numass/workspace/NumassGrindLauncher.java b/numass-main/src/main/java/inr/numass/workspace/NumassJavaGrindLauncher.java
similarity index 95%
rename from numass-main/src/main/java/inr/numass/workspace/NumassGrindLauncher.java
rename to numass-main/src/main/java/inr/numass/workspace/NumassJavaGrindLauncher.java
index ad8bb9f5..90765547 100644
--- a/numass-main/src/main/java/inr/numass/workspace/NumassGrindLauncher.java
+++ b/numass-main/src/main/java/inr/numass/workspace/NumassJavaGrindLauncher.java
@@ -17,7 +17,7 @@ import java.util.stream.Collectors;
 /**
  * Created by darksnake on 12-Aug-16.
  */
-public class NumassGrindLauncher {
+public class NumassJavaGrindLauncher {
 
     public static void main(String[] args) throws Exception {
         Options options = new Options();
diff --git a/numass-viewer/src/main/java/inr/numass/viewer/MainViewerController.java b/numass-viewer/src/main/java/inr/numass/viewer/MainViewerController.java
index 6b612577..5b0d2c10 100644
--- a/numass-viewer/src/main/java/inr/numass/viewer/MainViewerController.java
+++ b/numass-viewer/src/main/java/inr/numass/viewer/MainViewerController.java
@@ -137,7 +137,7 @@ public class MainViewerController implements Initializable {
                 NumassStorage root = NumassStorage.buildNumassRoot(path, true, false);
                 setRootStorage(root);
                 Platform.runLater(() -> storagePathLabel.setText("Storage: " + path));
-            } catch (StorageException ex) {
+            } catch (Exception ex) {
                 callback.setProgress(0);
                 callback.updateMessage("Failed to load storage " + path);
                 Logger.getLogger(MainViewerController.class.getName()).log(Level.SEVERE, null, ex);